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8,700 | Lovastatin specifically prevents focal ischemic ventricular tachycardia due to triggered activity. | Use of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor has been associated with reduced implantable defibrillator shocks in several multicenter trials, suggesting an antiarrhythmic effect.</AbstractText>The purpose of this study was to determine if lovastatin had an antiarrhythmic effect in a canine model of ischemic and inducible ventricular tachycardia (VT).</AbstractText>Forty-seven alpha-chloralose anesthetized dogs underwent left anterior descending coronary occlusion. Three-dimensional activation mapping identified the mechanism of reinducible VT and the response to lovastatin (0.5 mg/kg IV). The endocardium was excised from foci and studied using standard microelectrode techniques with Tyrode's solution.</AbstractText>Lovastatin blocked focal VT in 8 of 13 dogs (P <.01) compared with only 1 of 12 saline-treated dogs with focal VT. Lovastatin had no effect on reentrant VT. Lovastatin did not alter the effective refractory period, arterial pressure, or percentage of ischemic electrograms. Effective plasma concentration of lovastatin hydroxy acid ranged from 21-157 ng/mL (0.8-3.7 x 10(-7) M). In vitro rapid pacing, mostly with isoproterenol (5 x 10(-7) M) superfusion, produced delayed afterdepolarizations and triggered activity (9 +/- 2 action potentials). Lovastatin (10(-7) M) produced no change in action potentials or delayed afterdepolarizations. However, triggered activity was attenuated to 2 +/- 1 action potentials with lovastatin (P <.05, n = 13) but not with vehicle alone. Triggered activity returned to control after lovastatin washout (20 minutes) as well as with co-superfusion with mevalonic acid (10(-6) M, n = 5). 2,2,6,6-Tetramethylpiperidine-N-oxyl, an antioxidant that enters tissues (10(-3) M, n = 8), prevented triggered activity in a fashion similar to lovastatin.</AbstractText>Lovastatin, in concentrations achievable in human plasma, specifically suppresses triggered activity and focal VT due to ischemia. A prenylated protein downstream from mevalonic acid may act as an antioxidant, producing the antiarrhythmic effect.</AbstractText> |
8,701 | Human KCNQ1 S140G mutation is associated with atrioventricular blocks. | We recently reported that an S140G mutation in human KCNQ1, an alpha subunit of potassium channels, was involved in the pathogenesis of familial atrial fibrillation (AF), but it is not clear whether the mutation is associated with other cardiac arrhythmias.</AbstractText>The purpose of this study was to further explore the association of the KCNQ1 S140G mutation with cardiac arrhythmias.</AbstractText>We produced a transgenic mouse model with myocardium-specific expression of the human KCNQ1 S140G mutation under the control of an alpha-cardiac myosin heavy chain promoter by standard transgenic procedure and evaluated the relationship between the KCNQ1 mutation and its phenotypes in a human family.</AbstractText>Four lines of transgenic mice were established with a high level of human KCNQ1 S140G expression in the heart. Frequent episodes of first-, second-, advanced-, or third-degree atrioventricular block (AVB) occurred in at least 65% of transgenic descendants from the four lines. However, none of the five wild-type transgenic lines presented with AVBs. HMR1556, a KCNQ1-specific blocker, can terminate the AVBs. With the exception of at most three AF individuals, at least 13 AF patients were found to show obviously slow ventricular response, which may be one manifestation of AVBs. Interestingly, AF was not detected in these transgenic mice.</AbstractText>The results suggest that human KCNQ1 S140G is also likely to be a causative mutation responsible for AVBs. The transgenic mouse model is a potential tool to explore mechanisms of AVBs.</AbstractText> |
8,702 | Use of intracardiac echocardiography to guide implantation of a left atrial appendage occlusion device (PLAATO). | Over 90% of thrombi in atrial fibrillation (AF) originate from the left atrial appendage (LAA). Patients with contraindications to anticoagulation are potential candidates for LAA occlusion using the Percutaneous Left Atrial Appendage Transcatheter Occlusion system (PLAATO, ev3 Inc., Plymouth, MN). Transesophageal echocardiography (TEE) is typically used to guide implantation.</AbstractText>This study sought to examine the utility of intracardiac echocardiography (ICE) in providing adequate imaging guidance as an alternative to TEE during PLAATO implantation.</AbstractText>The study group consisted of 10 patients who underwent PLAATO implantation with simultaneous TEE and ICE imaging guidance. ICE was used to perform the following tasks typically fulfilled by TEE: (1) verification of the absence of LAA thrombus, (2) identification of the LAA ostial dimension for device sizing, (3) guidance of transseptal puncture, (4) verification of the delivery sheath position, and (5) confirmation of location and stability of device before its irrecoverable release. The ability of ICE to perform these tasks was assessed from three separate positions: the standard right atrial (RA) position, within the coronary sinus (CS), and the right ventricular outflow tract.</AbstractText>ICE imaging of the LAA was optimal from within the CS, although imaging from the proximal pulmonary artery provided better visualization of the distal LAA in cross-section. The LAA dimensions, confirmation of the absence of LAA thrombus, proper positioning of the delivery sheath, verification of location and stability of the device obtained by ICE were consistent with findings from TEE.</AbstractText>Using nonconventional imaging planes, ICE imaging was able to perform the intraprocedural functions provided by TEE during implantation of the PLAATO left atrial appendage occlusion device.</AbstractText> |
8,703 | Defibrillator availability on rotor-wing critical care transports. | Defibrillation is a time-critical and life-saving intervention for patients in ventricular fibrillation or ventricular tachycardia. The preparation of rotor-wing critical care transport teams to manage such arrhythmias out of the transport vehicle is unclear.</AbstractText>A mail and telephone survey of 230 rotor-wing critical care transport programs.</AbstractText>Transport teams take a defibrillator to the patient's side on scene flights at 23.9% of programs, on interfacility flights at 48.3%, and after off-load at the receiving hospital at 43.1% of programs. Monitor style and utilization are associated with defibrillator deployment on scene flights, interfacility flights, and at offload. The site of patient origin does not affect transport team defibrillator availability on offload.</AbstractText>It is not completely clear that defibrillators are immediately available during all phases of rotor-wing critical care transport. There are many opportunities for additional investigation.</AbstractText> |
8,704 | Shock outcome is related to prior rhythm and duration of ventricular fibrillation. | Several different ventricular fibrillation (VF) analysis features based on ECG have been reported for shock outcome prediction. In this study we investigated the influence of the time from VF onset to shock delivery (VF duration) and the rhythm before onset of VF, on the probability of return of spontaneous circulation (ROSC). We also analysed how these factors relate to the VF analysis feature median slope.</AbstractText>ECG recordings from 221 cardiac arrest patients from previously published prospective studies on the quality of CPR were used. VF duration and prior rhythm were determined when VF occurred during the episode. Median slope before each shock was calculated.</AbstractText>The median VF duration was shorter in shocks producing ROSC, 24 seconds (s) versus 70s (P<0.001). VF duration shorter than 30s resulted in 27% ROSC versus 10% for those longer than 30s (OR=3.5 [95% CI: 2.2-5.4]). The prior rhythm influenced the probability of ROSC, with perfusing rhythm being superior, followed by PEA, asystole, and "poor" PEA (broad complexes and/or irregular/very slow rate), respectively. The probability of ROSC corresponded well with the average median slope value for each group, but the correlation between median slope and VF duration was very poor (r2=0.05).</AbstractText>Based on our findings, detection of VF during ongoing chest compressions might be valuable because VF of short duration was associated with ROSC. Further, the rhythm before VF affects shock outcome with a perfusing rhythm giving the best prospect. The median slope can be used for shock outcome prediction, but not for determining VF duration. A combination could be beneficial and warrants further studies.</AbstractText> |
8,705 | Nitric oxide synthase isoform inhibition before whole body ischemia reperfusion in pigs: vital or protective? | Nitric oxide (NO) is a critical regulator of vascular tone, and signal transduction. NO is produced via three unique synthases (NOS); endothelial (eNOS), and neuronal (nNOS) are both constitutively expressed and inducible (iNOS) produced primarily after stimulation. NO has been implicated during and after ischemia reperfusion injury as both a detrimental and cardioprotective mediator. Since cardiopulmonary resuscitation (CPR) in ventricular fibrillation (VF) is a model of whole body ischemia reperfusion injury, it provides an opportunity to assess the effects of NO from the three NOS isoforms.</AbstractText>To determine the differential role of nitric oxide synthase isoforms inhibition in ventricular fibrillation CPR and investigate whether inhibition of the NOS isoforms afford any cardioprotection in this model.</AbstractText>Thirty-two pigs, weight range 25-35 kg, were assigned to four groups of eight animals each. The animals were randomized to receive (1) N(G)-nitro-L-arginine methyl ester (LNAME), a non-selective endothelial nitric oxide synthase inhibitor, (2) 1-(2-trifluoromethylphenyl) imidazole (TRIM), a selective neuronal NOS inhibitor, (3) aminoguanidine (AMINOG), a selective inducible NOS inhibitor or (4) saline control (Control) in equal volumes, 30 min before induction of ventricular fibrillation (VF). After 3 min VF with no intervention, the animals received standard chest compressions using an automated chest compression device (Thumper) for 15 min. After 18 min of VF, single doses of vasopressin and bicarbonate were given and defibrillation attempted. Hemodynamics, regional blood flows, and echocardiography and were performed, before and after drug infusion, during CPR, and after return of spontaneous circulation (ROSC).</AbstractText>ROSC for 3 h occurred in 5/8 (63%), 1/8 (13%), 0/8 (0%), and 6/8 (75%) in Control, LNAME, TRIM, and AMINOG treated animals, respectively. After infusion of LNAME, there was a significant increase from baseline in blood pressure [127+/-6 mmHg versus 169+/-3 mmHg, p<0.002] and coronary perfusion pressure [119+/-6 mmHg versus 149+/-6 mmHg, p<0.003]. During CPR, there were no differences among groups in hemodynamics or regional blood flow. In surviving animals, AMINOG had significantly better myocardial function (left ventricular ejection fraction, fractional shortening, and wall motion score index) than control or LNAME treated animals, and attenuated the post-resuscitation hyperemic response in heart and brain.</AbstractText>Intact basal nNOS activity is vital for survival from whole body ischemia reperfusion injury. iNOS inhibition prior to ischemia reperfusion, protects myocardial function after ROSC and decreases myocardial and brain hyperemic response after ROSC.</AbstractText> |
8,706 | Direct effects of apelin on cardiomyocyte contractility and electrophysiology. | Apelin, the ligand for the angiotensin receptor like-1, has been implicated in the pathogenesis of atrial fibrillation and heart failure. However, it is unknown if apelin has direct effects on cardiomyocyte contractility and electrophysiology. APJ-like immunoreactivity was localized to T-tubules and intercalated disc area in isolated adult rat ventricular myocytes. Apelin (1 nM) significantly increased sarcomere shortening in normal as well as failing cardiomyocytes. The transient increase in shortening was not accompanied by increased [Ca(2+)] transient amplitude. Apelin significantly activated the sarcolemmal Na(+)/H(+) exchanger (NHE) and increased intracellular pH. Moreover, apelin (10 nM) increased conduction velocity in monolayers of cultured neonatal rat cardiac myocytes. Our results demonstrate for the first time that apelin has direct effects on the propagation of action potential and contractility in cardiomyocytes. One of the mechanisms involved in the inotropic effect may be an increased myofilament sensitivity to Ca(2+) as apelin enhanced the activity of NHE with consequent intracellular alkalinization. |
8,707 | Ischaemic stroke, factor V Leiden heterozygosity and left atrial thrombosis in sinus rhythm: a case report. | We describe a 63-year-old man in sinus rhythm (SR) with an ischaemic stroke involving basal ganglia region on the right side. The patient was known to be heterozygous for factor V Leiden (FVL) mutation. On diagnostic work-up, no arterial sources of embolism were found. Transoesophageal echocardiography evidenced a left atrial (LA) thrombosis without relevant cardiopathies. LA thrombosis is generally associated to atrial fibrillation, atrial enlargement, mitral valve stenosis and left ventricular dysfunction, whereas mitral regurgitation is considered protective. To our knowledge, this is the first report of cardioembolic stroke related to a LA thrombosis in a patient in SR without risk factors for thrombus formation except for FVL heterozygosity. |
8,708 | Risk factors for prolonged intensive care treatment following atrial septal defect closure in adults. | Today, percutaneous or surgical closure of atrial septal defects (ASD) in adults are considered effective and safe treatments. However, some cases of severe left ventricular dysfunction after ASD closure were observed. This study aims at identifying predictors for prolonged intensive care unit stay, and postoperative inotropic support after ASD closure.</AbstractText>Records of 281 adult patients who had undergone surgical closure of a secundum ASD between 1974 and 2000 at an age over 30 years (mean 43.8, maximum 76 years) were reviewed retrospectively. The endpoints were defined as prolonged intensive care unit stay (>2 days), and postoperative inotropic support (Dopamine, Dobutamine or Adrenalin).</AbstractText>Thirty-day mortality rate was 0.7% (2 patients). Prolonged intensive care unit stay was observed in 70 patients (25%). Postoperative inotropic support was necessary in 84 patients (30%). Independent risk factors for prolonged intensive care unit stay in multivariate analysis were preoperative atrial fibrillation (p=0.011), and larger ASD (p=0.026). Older age at operation (p<0.001) and longer time on extracorporeal circulation (p<0.001) emerged as independent risk factor for postoperative use of inotropic support in multivariate analysis.</AbstractText>Surgical ASD closure in adults is usually safe. However, a distinct subgroup of patients is at risk for prolonged intensive care treatment. Timely closure of the ASD must be advised since older age emerged as a predictor for postoperative use of inotropic support. Since atrial fibrillation is a strong independent risk factor for prolonged intensive care unit stay the preservation of sinus rhythm must be aimed at.</AbstractText> |
8,709 | Use of conventional dual chamber pacemakers with custom lead adapters to induce atrial fibrillation or heart failure in dogs. | The purpose of this article is to show how custom "Y"-lead adapters and standard dual-chamber pacemakers can be used to produce pacing paradigms that will lead to stable experimental models of heart failure and atrial fibrillation.</AbstractText>With two custom lead adapters we used both ports of two dual-chamber clinical pacemakers to independently apply various pacing paradigms to either the ventricles or the atria of dogs.</AbstractText>Because both ports of the ventricular pacemaker were used to apply stimuli through one lead, the device did not have to be modified to obtain ventricular pacing rates that are sufficiently elevated to lead to tachycardia-induced heart failure. Similarly, simultaneous use of both ports of the atrial pacemaker can be used to apply stimuli through one atrial lead to induce sustained atrial fibrillation.</AbstractText>These techniques facilitate induction of experimental models of heart failure and atrial fibrillation without the need for modification of the clinical pacemaker.</AbstractText> |
8,710 | Idiopathic ventricular fibrillation successfully terminated by radiofrequency ablation of the distal Purkinje fibers. | A 21-year-old woman was admitted for evaluation of recurrent episodes of syncope. She had several spontaneous and abrupt loss of consciousness episodes while at the emergency department, caused by sustained and nonsustained ventricular fibrillation episodes. Each episode was initiated by a certain premature ventricular complex, which remained the same in subsequent ventricular fibrillation episodes. She had a total of eight more episodes of ventricular fibrillation during her admission, despite administration of intravenous antiarrhythmic agents. A diagnosis of idiopathic ventricular fibrillation was made. Radiofrequency catheter ablation was performed, targeting the distal Purkinje system. Ventricular fibrillation was noninducible after the procedure, and the patient has been symptom-free for the past 1 year. |
8,711 | The dilemma of ICD implant testing. | Ventricular fibrillation (VF) has been induced at implantable cardioverter defibrillator (ICD) implant to ensure reliable sensing, detection, and defibrillation. Despite its risks, the value was self-evident for early ICDs: failure of defibrillation was common, recipients had a high risk of ventricular tachycardia (VT) or VF, and the only therapy for rapid VT or VF was a shock. Today, failure of defibrillation is rare, the risk of VT/VF is lower in some recipients, antitachycardia pacing is applied for fast VT, and vulnerability testing permits assessment of defibrillation efficacy without inducing VF in most patients. This review reappraises ICD implant testing. At implant, defibrillation success is influenced by both predictable and unpredictable factors, including those related to the patient, ICD system, drugs, and complications. For left pectoral implants of high-output ICDs, the probability of passing a 10 J safety margin is approximately 95%, the probability that a maximum output shock will defibrillate is approximately 99%, and the incidence of system revision based on testing is < or = 5%. Bayes' Theorem predicts that implant testing identifies < or = 50% of patients at high risk for unsuccessful defibrillation. Most patients who fail implant criteria have false negative tests and may undergo unnecessary revision of their ICD systems. The first-shock success rate for spontaneous VT/VF ranges from 83% to 93%, lower than that for induced VF. Thus, shocks for spontaneous VT/VF fail for reasons that are not evaluated at implant. Whether system revision based on implant testing improves this success rate is unknown. The risks of implant testing include those related to VF and those related to shocks alone. The former may be due to circulatory arrest alone or the combination of circulatory arrest and shocks. Vulnerability testing reduces risks related to VF, but not those related to shocks. Mortality from implant testing probably is 0.1-0.2%. Overall, VF should be induced to assess sensing in approximately 5% of ICD recipients. Defibrillation or vulnerability testing is indicated in 20-40% of recipients who can be identified as having a higher-than-usual probability of an inadequate defibrillation safety margin based on patient-specific factors. However, implant testing is too risky in approximately 5% of recipients and may not be worth the risks in 10-30%. In 25-50% of ICD recipients, testing cannot be identified as either critical or contraindicated. |
8,712 | Incidence and initial characteristics of pilsicainide-induced ventricular arrhythmias in patients with Brugada syndrome. | In patients with Brugada syndrome, class I antiarrhythmic drugs can trigger ventricular arrhythmias (VA). The incidence and initial characteristics of VA that developed after pilsicainide was examined in 28 patients with Brugada-type electrocardiographic (ECG) abnormalities and with a positive response in the pilsicainide test. The clinical outcome was also compared between patients with and without pilsicainide-induced VA.</AbstractText>In all patients, pilsicainide increased ST segment elevation and accentuated type 1 ECG changes. Ventricular tachycardia (VT) developed in 3 patients and premature ventricular complexes (PVC) in 2 other patients. These 5 patients (group I) had higher ST segment elevation in lead V2 on the ECG at baseline and after pilsicainide and showed a longer QTc interval after pilsicainide than the other 23 patients (group II). However, there was no difference between the 2 groups regarding incidence of prior cardiac events, results of signal-averaged ECG, HV interval, inducibility of ventricular fibrillation by programmed electrical stimulation, or QRS duration. In 1 patient, PVC originated from 3 sites, 2 of which triggered polymorphic VT. The right ventricular (RV) outflow tract was the origin of 2 types of PVC, and other RV sites of 5 other types. During a 45 +/- 37 months follow-up, polymorphic VT recurred in 2 patients in group II.</AbstractText>Pilsicainide induced VA in some patients with Brugada syndrome, but this result may not be used as a parameter of the risk stratification of Brugada syndrome. Multiple PVC induced by pilsicainide and triggering polymorphic VT originated from several RV sites is an important factor when considering patients for treatment with catheter ablation.</AbstractText> |
8,713 | Achieving sufficient safety margins with fixed duration waveforms and the use of multiple time constants. | There are several options to achieve a sufficient safety margin in a patient with a high defibrillation threshold (DFT), with varying and typically modest success. Programming fixed (millisecond) durations of both phases of a biphasic waveform in an implantable cardioverter defibrillator (ICD) has demonstrated utility.</AbstractText>We established an informal multisite registry of ICD implanting facilities. Each facility agreed to attempt the use of fixed duration waveforms whenever there was an inadequate safety margin with tilt-based waveforms. A 3.5-ms-based fixed duration shock was tried first. If that failed to achieve a 10-J safety margin then a 2-ms-based shock was used. We also tabulated an HEDFT (high estimate DFT) as precise DFTs were not determined.</AbstractText>Sixteen patients (15 M, 1 F) were entered into the registry (age 58.2 +/- 17.9 years) with ejection fractions of .30 +/-.11. Superior vena cava coils were used in 7 patients according to physician preference. The tilt-based HEDFTs were 35.4 +/- 3.2 J delivered and 35.8 +/- 3.3 J stored energy. The 3.5-ms based shocks were evaluated on 14 patients and the HEDFT fell to 23.4 +/- 6.3 J delivered (P < 0.0001) and 26.2 +/- 6.9 J stored energy (P < 0.0001). The 2-ms-based fixed duration shocks were then evaluated on 6 patients and the delivered energy HEDFT was 22.2 +/- 5.8 J (P = 0.001 vs. tilt-based shocks) while the stored energy HEDFT was 27.9 +/- 6.4 J (P = 0.01 vs. tilt-based shocks). Using the better of the two fixed duration waveforms, the mean safety margin was improved from -1.2 +/- 1.9 J to 9.5 +/- 5.9 J (P < 0.00001). Multivariate predictors of the safety margin improvement were the absence of the Superior Vena Cava (SVC) coil and absence of Ventricular fibrillation (VF) presentation. Four patients still required lead repositioning after the use of the fixed duration waveforms. No additional leads were implanted.</AbstractText>The use of a selection of directly programmed fixed duration biphasic shocks had a striking impact on the HEDFT for these difficult patients. Adequate safety margins were obtained for 12 of 16 patients with no lead manipulation or other approaches.</AbstractText> |
8,714 | [A case of right ventricular ischemia mimicking acute myocardial infarction during coronary angioplasty on the right coronary artery]. | A 55-year-old man was admitted to our department with a diagnosis of acute inferior myocardial infarction; 1 week later he underwent percutaneous transluminal coronary angioplasty on the proximal right coronary artery; during this procedure, the patient experienced chest pain and his electrocardiogram showed ST-segment elevation in the anterior leads; ventricular fibrillation also occurred. The ST-segment abnormality disappeared within 45 min, and no stenosis or spasm on the left coronary artery were detected during angiographic control; the blood flow in the right coronary artery was normal, but the acute marginal branch was occluded. This is a rare case of right ventricular ischemia caused by occlusion of the acute marginal branch during coronary angioplasty on the right coronary artery. |
8,715 | Prognosis of patient with cardiopulmonary arrest transported to Kyushu University Hospital. | Three hundreds and sixty six patients with out-of-hospital cardiopulmonary arrest, transported to the Kyushu University Hospital from 2000 to 2006, were examined using the Utstein style in witnessed cardiogenic cardiopulmonary arrest patients. Also, we examined the influence on prognosis due to the difference in the treatment of airway control in out-of-hospital settings. Nineteen patients out of 78 witnessed cardiogenic out-of-hospital cardiopulmonary arrest patients were discharged alive and 11 were with a good prognosis. The number of cases where an initial electrocardiographic complex showed ventricular fibrillation or pulseless ventricular tachycardia was higher than formerly reported in Japan and was equal to the incidence reported in Europe and America. In addition, the survival discharge rate of patients with the ventricular fibrillation or pulseless ventricular tachycardia was higher than that previously reported in Japan and was similar to European and American results. Manual airway maintenance using a bag valve mask was more successful in terms of the survival discharge rate compared to the use of advanced airway devices. By the time course, collapse to cardiopulmonary resuscitation interval, collapse to initial defibrillation interval and collapse to the return of spontaneous circulation interval were shorter in the group discharged with a good prognosis, especially in the witnessed ventricular fibrillation or pulseless ventricular tachycardia patients corresponding to former reports. Most patients with a good prognosis resuscitated before arrival at the hospital. These results suggest the prehospital treatment is the critical point other than in-hospital treatment. |
8,716 | Noninvasive assessment of left atrial function by strain rate imaging in patients with hypertension: a possible beneficial effect of renin-angiotensin system inhibition on left atrial function. | Renin-angiotensin system (RAS) inhibitors are likely to reduce the development of atrial fibrillation by preventing atrial fibrosis. Strain rate (SR) imaging is a novel echocardiographic technique to quantify left atrial (LA) function. However, it has not been determined whether SR imaging is applicable for detection of LA dysfunction in hypertensive (HT) patients. We used SR imaging to assess alteration in LA function in HT patients and its modification by RAS inhibitors. SR imaging was performed in 80 HT patients and 50 age-matched normotensive (NT) subjects. HT patients were divided into two groups according to left ventricular hypertrophy (LVH) and LA dilatation. Peak SR was measured at each LA segment (septal, lateral, posterior, anterior, and inferior) and mean peak systolic SR (SR-LAs) was calculated by averaging data in each segment. Mean SR-LAs levels in the dilated LA group (1.97+/-0.45 s(-1), n=25) and non-dilated LA group (2.15+/-0.57 s(-1), n=55) were significantly (p<0.05) lower than that in NT subjects (2.53+/-0.71 s(-1)). Irrespective of the presence or absence of LVH, mean SR-LAs in HT patients was lower than that in NT subjects. When RAS inhibitors were used, the mean SR-LAs level in the non-dilated LA group was equivalent to that in NT subjects. In HT patients, mean SR-LAs, an index of LA reservoir function, decreases before development of LA enlargement and LVH. Treatment with RAS inhibitors appears to preserve LA reservoir function in HT patients without dilated LA. SR imaging can detect LA dysfunction in HT patients and is useful for evaluation of the therapeutic benefit on LA reservoir function. |
8,717 | Gamma-irradiated ceruloplasmin affords antifibrillatory protection against ischemia/reperfusion damage in the isolated rat heart. | Ceruloplasmin (CP), an important serum antioxidant, was previously found to reduce the incidence of ventricular fibrillation (VF) induced by ischemia and reperfusion in isolated rat hearts. The present study investigated whether CP sterilized by gamma-irradiation maintains its antiarrhythmic capacity and in vitro antioxidant properties.</AbstractText>Isolated rat hearts submitted to regional ischemia (15 min), were reperfused (10 min) with native CP or with CP irradiated at various doses (1-3 kGy) in the absence or presence of tyrosine (Tyr).</AbstractText>All untreated hearts showed VF at reperfusion, which were all irreversible ventricular fibrillation (IVF). No IVF were found in hearts treated with native CP or gamma-irradiated CP. Cardioprotection afforded by irradiated CP (with or without Tyr) was slightly higher than that obtained with native CP. No VF at all (100% prevention) was found in hearts treated with CP irradiated alone or in the presence of tyrosine at 3 kGy. Tyrosine and irradiated tyrosine had no cardiotoxic or protective effects on reperfusion-induced arrhythmias. The Oxygen Radical Absorbing Capacity (ORAC), measured in vitro with beta-phycoerythrin (beta-PE) fluorescent indicator, was slightly higher for gamma-irradiated CP in the presence of Tyr.</AbstractText>Ceruloplasmin sterilized by gamma-irradiation maintains antioxidant and antiarrhythmic effects in the post-ischemia reperfused isolated rat heart.</AbstractText> |
8,718 | Postresuscitation accelerated idioventricular rhythm: a potential prognostic factor for out-of-hospital cardiac arrest survivors. | Data are lacking on the relationship between postresuscitation ECG and outcome in out-of-hospital cardiac arrest (OHCA). We examined the prognostic information that postresuscitation ECG rhythm can provide for predicting outcome in OHCA survivors.</AbstractText>The retrospective observational study enrolled 56 successfully resuscitated nontraumatic adult OHCA patients. Postresuscitation 12-lead ECGs of the enrolled patients were interpreted independently by two cardiologists. We compared baseline clinical characteristics, CPR process, and outcome in the 8 patients with postresuscitation accelerated idioventricular rhythm (AIVR, n = 8) and the 48 without AIVR.</AbstractText>The AIVR group had a higher proportion of patients with coronary artery disease (50% vs. 15%), initial ventricular tachycardia/fibrillation rhythm (50% vs. 8%), and cardiac origin of OHCA (75% vs. 23%). AIVR patients had longer total CPR duration (32 vs. 18 min) and higher dose of epinephrine use (10 vs. 3 mg). Postresuscitation AIVR was associated with an increased incidence of repeated CPR within 1 h after return of spontaneous circulation (38% vs. 4%), and lower 7-day survival rate (0% vs. 50%).</AbstractText>AIVR on postresuscitation ECG offers a prognostic factor related to a higher repeated CPR rate within 1h after return of spontaneous circulation and a lower 7-day survival rates in successfully resuscitated OHCA victims.</AbstractText> |
8,719 | Utility of intracardiac echocardiography in left heart ablation for tachyarrhythmias. | Catheter-based radiofrequency ablation in the left heart can provide effective therapy for tachyarrhythmias. The recent development of the real time intracardiac echocardiography (ICE) with 2D and Doppler color flow imaging can facilitate left heart ablation procedures. This report reviews the use of ICE during radiofrequency catheter ablation procedures for atrial fibrillation (AF) and ventricular tachycardia and is based on our own experience in 955 patients. ICE has a critical role for guiding transseptal catheterization, assisting placement of mapping/ablation catheters and monitoring lesion morphologic changes, especially in the pulmonary vein ostia, Marshall ligament region, thickened interatrial septum, left atrial posterior wall contiguous to esophagus, aortic valve cusps, and the epicardial regions. One of the more powerful utilities of ICE lies in its ability to identify and potentially reduce procedural complications including damage to intracardiac structures, residual atrial septal defect, left atrial thrombus formation, pulmonary vein stenosis, esophageal injury, myocardial air-embolization and pericardial effusion during left heart ablation. |
8,720 | Usefulness of bedside tissue Doppler echocardiography and B-type natriuretic peptide (BNP) in differentiating congestive heart failure from noncardiac cause of acute dyspnea in elderly patients with a normal left ventricular ejection fraction and permanent, nonvalvular atrial fibrillation: insights from a prospective, monocenter study. | The incremental role of bedside tissue Doppler echocardiography and B-type natriuretic peptide (BNP) over the clinical judgment has been recently reported in the emergency diagnosis of congestive heart failure with a normal left ventricular ejection fraction (HFNEF). However, how well does this diagnostic strategy be applicable in the setting of atrial fibrillation is unknown.</AbstractText>To investigate the usefulness of bedside tissue Doppler echocardiography and BNP in the emergency diagnosis of HFNEF in elderly patients with permanent, nonvalvular atrial fibrillation.</AbstractText>Forty-one consecutive elderly patients with an ejection fraction > or =50% (mean age 84 years; 22 with HFNEF and 19 with noncardiac cause), hospitalized for acute dyspnea at rest, were prospectively enrolled; bedside septal E/Ea and BNP were obtained at admission.</AbstractText>By multivariable logistic regression analysis including the clinical judgment of heart failure, E/Ea and BNP, E/Ea (P = 0.014) and BNP (P = 0.018) provided independent diagnostic information. Optimal cutoffs were 13 for E/Ea (area under the ROC curve of 0.846, P < 0.0001; sensitivity 81.8%, specificity 89.5%) and 253 pg/ml for BNP (area under the ROC curve of 0.928, P < 0.0001; sensitivity 86.4%, specificity 89.5%). The concordance between the clinical judgment and BNP concentration at the cutoff of 253 pg/ml correctly classified 24 of 25 patients; E/Ea at the cutoff of 13 correctly classified 14 of the 16 patients with discrepancy.</AbstractText>Bedside tissue Doppler echocardiography and BNP provide useful additional diagnostic information over the clinical judgment for the emergency diagnosis of HFNEF in elderly patients with permanent, nonvalvular atrial fibrillation.</AbstractText> |
8,721 | Effects of an impedance threshold device on hemodynamics and restoration of spontaneous circulation in prolonged porcine ventricular fibrillation. | An impedance threshold device (ITD) has been designed to enhance circulation during CPR by creating a negative intrathoracic pressure during the relaxation phase of chest compression.</AbstractText>We sought to determine the effects of the ITD on coronary perfusion pressure (CPP), return of spontaneous circulation (ROSC), and short-term survival (20 minutes after ROSC). We hypothesized that the ITD would improve all 3 variables when compared to standard CPR.</AbstractText>Using a case-control design nested within a randomized primary study, we compared CPR with the ITD (ITD-CPR) to standard CPR without the device (S-CPR). We systematically assigned 36 domestic swine, weighing 23-29 kg, (18 per group) to resuscitation with either ITD-CPR or S-CPR after 8 minutes of untreated ventricular fibrillation (VF). At minute 8, mechanical chest compression and ventilation began, and drugs (0.1 mg/kg epinephrine, 40U vasopressin, 1.0 mg propranolol, 1 mEq/kg sodium bicarbonate) were given. The first rescue shock (150J biphasic) was delivered at minute 11 of VF. We recorded CPP, ROSC (systolic pressure > 80 mmHg sustained for 60 s continuously), and survival. Data were analyzed with Fisher's exact test and generalized estimating equations (GEE), with alpha = 0.05.</AbstractText>We analyzed 3,150 compressions. CPP for the ITD-CPR group (28.1 mmHg [95% CI 27-29.3 mmHg]), did not differ from the S-CPR group (32.3 mmHg [95% CI 31.2-33.4 mmHg]). ROSC occurred in 6/18 (33%) animals in the ITD-CPR, and 14/18 (78%) in the S-CPR group (p = 0.02). Survival occurred in 3/18 (17%) ITD-CPR and 13/18 (72%) S-CPR group (p = 0.003).</AbstractText>ITD-CPR did not improve CPP compared to S-CPR. ROSC and survival were significantly lower with ITD-CPR.</AbstractText> |
8,722 | Differentiation between the two types of amiodarone-associated thyrotoxicosis using duplex and amplitude Doppler sonography. | To evaluate the usefulness of Doppler parameters in the differentiation between the two types of amiodarone-associated thyrotoxicosis (AAT).</AbstractText>One hundred thirty-seven individuals were selected at our institution. They were divided into four groups: 84 normal subjects (N), 30 euthyroids taking amiodarone (A), 14 AAT type 1 patients (AAT1), and nine AAT type 2 patients (AAT2). Each AAT type was classified according to (131)I uptake and clinical outcome. Blindly, the resistance and pulsatility indexes (RI, PI), systolic peak velocity, and color pixel density (CPD) were calculated.</AbstractText>AAT1 had greater CPD than AAT2 (P = 0.02). The latter group had similar vascularization to the N and A groups (P = 0.45). The area under the receiver operating characteristic (ROC) curve showed that systolic peak velocity in the inferior thyroid arteries and CPD were the best parameters in the differentiation between AAT type 1 and AAT type 2 (Az = 0.83 and 0.84, respectively). Impedance indexes were useless.</AbstractText>Our results demonstrate that objective tests such as systolic peak velocities in the thyroid arteries and CPD are reliable parameters for differentiating between the two types of AAT.</AbstractText> |
8,723 | Interventional electrophysiology and cardiac resynchronization therapy: delivering electrical therapies for heart failure. | Implantable devices have become a readily available option for patients with heart failure. Not only do these patients develop bradycardia and ventricular tachycardia, but their ventricular dysfunction can often improve with cardiac resynchronization therapy. However, this is a complex and rapidly developing clinical science for which the physician chooses techniques and selects patients on the basis of the results of clinical trials, clinical experience, and rapidly evolving tools. The results depend on the interplay of these complex variables. Placement of the left ventricular lead has forced the device physician to develop new skills and/or interdisciplinary relationships with physicians with vascular intervention, imaging, and surgical skills. Familiarity with the cardiac venous anatomy, occlusive venography, venoplasty, guide wire tools, guiding catheters, stenting, and new intracardiac visualization and magnetic intracardiac lead positioning tools are examples of just a few of the novel skills that are useful in the delivery of cardiac resynchronization therapy. Beyond implantation, these patients and devices require specialized follow-up with continued medical therapy and echo-guided adjustments of device programming. Finally, there are ongoing controversies and many as yet unanswered questions that are the subject of ongoing and planned clinical trials. |
8,724 | Long-term survival after successful inhospital cardiac arrest resuscitation. | Little is known about long-term outcomes of patients who survive inhospital cardiac arrest.</AbstractText>We examined long-term survival after inhospital cardiac arrest and whether procedural changes that improved survival to discharge impacted long-term survival. Consecutive inhospital arrests in the Atlanta Veterans Affairs Medical Center (Atlanta, GA) from 1995 to 2004 (n = 732) were retrospectively analyzed. Data regarding the arrest was obtained, including age, left ventricular ejection fraction, medications, and comorbidities, presenting rhythm, location of arrest, code duration, and outcomes. Long-term mortality data was obtained based on chart and Social Security Death Index reviews. Further data was gathered on internal cardioverter-defibrillator presence and use in survivors.</AbstractText>Overall, 49 subjects (6.6%) survived to discharge. Univariate analysis found that ventricular tachycardia/ventricular fibrillation and the use of beta-blockers, angiotensin-converting enzyme inhibitors, and antiarrhythmics at the time of arrest were associated with increased survival, whereas advancing age and comorbidities were associated with a higher risk of mortality. Multivariate analysis determined that age, rhythm, and comorbidities independently affected survival. Implementation of a resuscitation program previously documented to improve survival to discharge did not translate to durable long-term survival. Three-year survival rate after discharge was only 41%. Alternatively, subjects with internal cardioverter-defibrillator showed a 36% improvement in 3-year survival rate to 77% (P = .001).</AbstractText>Subjects with inhospital cardiac arrest have poor long-term prognoses. A strategy that improved inhospital survival did not alter long-term mortality rate. Thus, survival to discharge may not be a sufficient end point for future resuscitation trials.</AbstractText> |
8,725 | Outcome after out-of-hospital cardiac arrest in a physician-staffed emergency medical system according to the Utstein style. | Despite a large amount of data assessing outcomes of out-of-hospital cardiac arrests (OHCAs), little information is available about physician-staffed emergency medical service (EMS) systems. The aim of our study was to investigate the impact of a physician on the outcome of patients after OHCA.</AbstractText>This is a prospective, observational study that included 539 consecutive patients (63.9 +/- 19.1 years old; 349 males) with OHCA in the community of Dachau (135,000 inhabitants) in whom resuscitation was attempted between January 2000 and January 2006 according to Utstein style. Patients were followed up to hospital discharge. The primary end point of the study was that the patients was discharged alive from hospital.</AbstractText>Of 412 patients with an OHCA, 180 (43.7%) were admitted to hospital, and 47 (11.4%) were discharged alive. Resuscitation was started by a physician in 117 (28.4%) patients, by a layperson in 118 (28.6%), or by an EMS personnel in 177 (43.0%). A total of 18 patients (18.6%) treated by physicians, 13 patients (8.0%) treated by EMS personnel (P = .02 vs treatment by physician), and 16 patients (16.5%) resuscitated by laypersons were discharged from hospital (P = .8 vs treatment by physician). In 105 patients with bystander-witnessed OHCA of cardiac origin with shockable rhythm, the discharge rate was 32.4% (n = 34). Multivariate analysis identified ventricular fibrillation on first electrocardiogram, observed OHCA, short response time intervals but not the unit that performed the first resuscitation attempt as independent predictors of survival.</AbstractText>A physician on board of the advanced life support unit was not identified as an independent factor of improved survival.</AbstractText> |
8,726 | The relationship between shocks and survival in out-of-hospital cardiac arrest patients initially found in PEA or asystole. | To describe survival rates from out-of-hospital cardiac arrest for patients who present with pulseless electrical activity or asystole according to whether they remained in a non-shockable rhythm or converted to ventricular fibrillation and were shocked appropriately.</AbstractText>Observational analysis of a cardiac arrest registry collected as part of a randomized trial.</AbstractText>Five urban/suburban cities in the United States and Canada.</AbstractText>Trial subjects (adult, treated, non-traumatic) whose first documented heart rhythm/state following cardiac arrest was asystole or pulseless electrical activity.</AbstractText>Periodic pauses to assess for shockable rhythm.</AbstractText>Survival to hospital discharge.</AbstractText>Of 1377 cardiac arrest patients, 738 presented with an initial arrest rhythm/state of either pulseless electrical activity or asystole. Of the 738, 78% (n=574) subsequently remained in a non-shockable rhythm/state at each evaluation throughout the resuscitation (No-Shock group) while 22% (n=164) converted to ventricular fibrillation and were shocked by emergency medical service (Shock group). Survival to hospital discharge was significantly greater in the No-Shock group (4.9% versus 0.6%, p=0.01). Shock group remained a predictor (odds ratios=0.18, p=0.036) of death after adjustment for potential confounders.</AbstractText>These results suggest that patients with cardiac arrest who develop VF during the course of treatment for initially observed pulseless electrical activity or asystole do not benefit from conventional approaches to treatment such as defibrillation. Further study is warranted to define the optimal treatment of this patient cohort.</AbstractText> |
8,727 | Ventricular fibrillation induced by transoesophageal cardiac pacing: a new model of cardiac arrest in rats. | To investigate whether transoesophageal cardiac pacing can induce ventricular fibrillation (VF) and how long the cardiac pacing has to be sustained to prevent the reversion of the VF induced.</AbstractText>A pacing electrode was inserted orally into the oesophagus and high-frequency ventricular pacing was performed so as to elicit VF in 25 Sprague-Dawley rats. Incidences of VF and time of cardiac pacing were observed and recorded. Four minutes after onset of VF cardiopulmonary resuscitation (CPR) was initiated.</AbstractText>A short interval of high-frequency ventricular pacing caused an immediate drop of blood pressure, loss of pulse and increase of right atrial pressure in the same time frame. When the cardiac pacing was terminated, VF was elicited at least once or more than once in all of the 25 rats. However, the VF elicited by the burst stimulation could be defibrillated spontaneously. With the prolongation (120-180 s) of cardiac pacing, the incidence of defibrillation of VF decreased from 100 to 0%. VF persisted in 19 of 25 animals, developed into asystole in 5 of 25 animals and converted into pulseless electrical activity in 1 of 25 animals prior to CPR. Following CPR 22 of 25 animals were resuscitated.</AbstractText>Transoesophageal cardiac pacing can induce VF in rats. However, the cardiac pacing is required for at least 120-180 s to ensure that VF does not spontaneously convert. We can use the technique to establish a new and simpler rat cardiac arrest (CA) model, which may facilitate experimental investigation on CPR.</AbstractText> |
8,728 | [Chronic heart failure treatment in the year 2006]. | Heart failure (HF) has a high incidence, near 2% of the population suffered this process, that increases with the age, affecting between 15-20 % of the population elder than 70 years. In the last 20 years the knowledge in pathophysiological mechanisms has improved, mainly, the role of neurohormonal response in the development and worsening of HF. In the last 15 years the efficient blockade of these mechanisms have improved the follow-up of these patients. The use of Angiotensin Converting Enzyme inhibitors, angiotensin II receptor blockers, Beta-blockers and antialdosteronic drugs have significantly decreased cardiovascular morbidity and mortality of these patients. Nevertheless 50% of patients with HF dies for electrical disturbance of the ventricular rithm, tachycardia and ventricular fibrillation. Also, disorders of intraventricular conduction worsen the functional degree. The implantable cardioverter defibrillator reduce mortality in patients at higher risk for mortality due to HF and Cardiac Resynchronization Therapy may lead to remarkable improvement in clinical status in selected patients with HF. Other measures, as cardiac transplantsand implantable left ventricular assist devices are becaming more exceptional in all occidental countries. Cell transplantation is an innovative technology and has the potential to revolutionize alternative therapeutic approaches to management of heart failure, but still a numkber of problems persist before the extending use of these techniques. |
8,729 | Left atrial remodelling contributes to the progression of asymptomatic left ventricular systolic dysfunction to chronic symptomatic heart failure. | Systolic heart failure (HF) is a progressive disorder that often begins with asymptomatic left ventricular (LV) systolic dysfunction and culminates in symptoms from fluid overload and poor end-organ perfusion. The progression to symptomatic HF is accompanied by marked activation of neurohormonal and cytokine systems, as well as a series of adaptive LV anatomical and functional changes, collectively referred to as LV remodelling. However, the mechanisms underlying symptom appearance have not been delineated and the weight of experimental and clinical evidence suggests that the development of symptomatic HF occurs independently of the haemodynamic status of the patient. The left atrium is a muscular chamber strategically located between the left ventricle and the pulmonary circulation with important mechanical function (modulation of LV filling), which is closely coupled with its endocrine (atrial natriuretic peptide synthesis and secretion) and regulatory (contribution to the control of sympathetic activity and vasopressin release) functions. In this narrative review we provide evidence supporting the concept that left atrial dilation and systolic dysfunction (left atrial remodelling) contributes to the progression of asymptomatic LV dysfunction to chronic symptomatic systolic HF as it is a prerequisite for the development of the pulmonary congestion and marked neuronhormoral activity that characterize the symptomatic state. |
8,730 | Resynchronization therapy in the context of atrial fibrillation: benefits and limitations. | Atrial fibrillation (AF) and heart failure often coexist and are believed to directly predispose to each other. Cardiac resynchronization does not prevent or increase the induction of AF. However, new onset of AF does not seem to diminish the beneficial effects of CRT on symptoms, cardiac function and, more importantly, all-cause mortality if appropriate ventricular rate control by beta-blockers and digoxin is being achieved. While a pharmacological approach to control ventricular rate may be sufficient in most patients with paroxysmal AF or AF of shorter duration in those with permanent AF ablation strategies may be necessary. Observational studies and one randomized trial indicate a potential benefit of CRT in heart failure patients with chronic AF; particularly, biventricular pacing was superior compared to conventional right-univentricular stimulation. However, recent results suggest that even relatively high percentage biventricular capture may be inadequate, and that the benefits of CRT may only be extended to chronic AF patients with previous AV junctional ablation. Well designed and powered clinical trials are required before pacemaker dependency is created in large numbers of heart failure patients. |
8,731 | Use of intravenous magnesium to treat acute onset atrial fibrillation: a meta-analysis. | To assess the effects of intravenous magnesium on converting acute onset atrial fibrillation to sinus rhythm, reducing ventricular response and risk of bradycardia.</AbstractText>Randomised controlled trials evaluating intravenous magnesium to treat acute onset atrial fibrillation from MEDLINE (1966 to 2006), EMBASE (1990 to 2006) and Cochrane Controlled Trials Register without language restrictions.</AbstractText>Two researchers independently performed the literature search and data extraction.</AbstractText>10 randomised controlled trials, including a total of 515 patients with acute onset atrial fibrillation, were considered. Intravenous magnesium was not effective in converting acute onset atrial fibrillation to sinus rhythm when compared to placebo or an alternative antiarrhythmic drug. When compared to placebo, adding intravenous magnesium to digoxin increased the proportion of patients with a ventricular response <100 beats/min (58.8% vs 32.6%; OR 3.2, 95% CI 1.93 to 5.42; p<0.001). When compared to calcium antagonists or amiodarone, intravenous magnesium was less effective in reducing the ventricular response (21.4% vs 58.5%; OR 0.19, 95% CI 0.09 to 0.44; p<0.001) but also less likely to induce significant bradycardia or atrioventricular block (0% vs 9.2%; OR 0.13, 95% CI 0.02 to 0.76; p = 0.02). The use of intravenous magnesium was associated with transient minor symptoms of flushing, tingling and dizziness in about 17% of the patients (OR 14.5, 95% CI 3.7 to 56.7; p<0.001).</AbstractText>Adding intravenous magnesium to digoxin reduces fast ventricular response in acute onset atrial fibrillation. The effect of intravenous magnesium on the ventricular rate and its cardiovascular side effects are less significant than other calcium antagonists or amiodarone. Intravenous magnesium can be considered as a safe adjunct to digoxin in controlling the ventricular response in atrial fibrillation.</AbstractText> |
8,732 | Mechanisms, prediction and treatment of ventricular tachyarrhythmias occurring late after myocardial infarction. | Studies from the 1980s, refined in the intervening years, have examined the milieu for ventricular tachycardia (VT) and ventricular fibrillation (VF) occurring late after acute myocardial infarction (AMI). The arrhythmogenic substrate appears to be patchy areas of fibrous tissue interdigitating with viable bundles of myocardium which have distorted orientation and tortuous interconnections. These promote conduction delay in sinus rhythm. Factors found to promote induction of VT rather than VF are longer conduction delay in sinus rhythm, larger infarct size, a more ragged infarct edge and longer ventricular extrastimulus coupling intervals. Predictors of spontaneous VT and VF late after AMI include inducible VT at electrophysiological studies (EPS), delayed conduction in sinus rhythm detected as late potentials on signal-averaged surface electrocardiogram (ECG), and low left ventricular ejection fraction (LVEF). Treatments of propensity for VT or VF after AMI include insertion of a defibrillator (ICD), which has the best track record, antiarrhythmic medication (less reliable), and ablation or excision of arrhythmogenic substrate (for refractory VT and VF). |
8,733 | Spironolactone reduced arrhythmia and maintained magnesium homeostasis in patients with congestive heart failure. | Patients with congestive heart failure (CHF) often have increased aldosterone activity that leads to hypomagnesemia. Hypomagnesemia can induce arrhythmias, an important cause of death in patients with CHF. We determined whether the aldosterone receptor antagonist spironolactone improved magnesium homeostasis and reduced arrhythmias in patients with CHF.</AbstractText>We randomized 116 consecutive patients with CHF into placebo control group (n = 58) and spironolactone group (20 mg daily, n = 58) in addition to conventional therapy. Plasma magnesium concentration (PMC), erythrocyte magnesium concentration (EMC), and erythrocyte magnesium efflux were not different between the 2 groups of patients before treatment. Compared with control patients, patients treated with spironolactone for 6 months had increased PMC and EMC and decreased erythrocyte magnesium efflux. Patients on spironolactone therapy also had a marked decrease of 24-hour mean heart rate, ventricular and atrial premature beats, and the risk of atrial fibrillation/flutter. Pooled data from the 116 patients showed that patients with a higher EMC or a lower sodium-dependent erythrocyte magnesium efflux had a slower heart rate, fewer ventricular premature beats, and a lower risk of atrial fibrillation/flutter.</AbstractText>Our results suggest that reducing cellular magnesium efflux and loss may contribute to the spironolactone-reduced arrhythmias in patients with CHF.</AbstractText> |
8,734 | Accuracy of electrocardiogram interpretation improves with emergency medicine training. | To assess whether electrocardiogram (ECG) interpretation accuracy improves with advancing years of emergency medicine training.</AbstractText>A prospective cross-sectional double-blinded study of emergency medicine trainees attending teaching sessions in ACEM accredited Victorian hospitals. Subjects completed a survey about level of training, rotations completed and ECG training. They were then asked for the 'main diagnosis' on 10 clinically significant ECG. Those in their fourth year of advanced training onwards, or in active preparation for fellowship examination (senior trainees) were compared with trainees in earlier years (other trainees).</AbstractText>There were 122 trainees surveyed in total. In the present study, 48/122 were senior trainees and 74/122 were other trainees. The overall accuracy of ECG interpretation was 67.5% (95% confidence interval [CI] 63.2-71.8%) for the senior trainees and 49.6% (95% CI 45.2-53.9%) for the others. Results for some of the individual ECG were: left bundle branch block: 81.3% (95% CI 69.9-92.6%) seniors and 58.1% (95% CI 46.6-69.7%) others; ventricular tachycardia: 43.8% (95% CI 29.3-58.2%) seniors and 37.8% (95% CI 26.5-49.2%) others; and ventricular fibrillation: 70.8% (95% CI 57.6-84.1%) seniors and 63.5% (95% CI 52.2-74.9%) others.</AbstractText>There is an improvement in ECG interpretation accuracy with advancing years of emergency medicine training in Victoria. There exists, however, a low level of accuracy for some critical ECG diagnoses. There is a call by trainees for more formalized and regular ECG education to begin earlier in their training.</AbstractText> |
8,735 | [Heterotaxia syndrome without congenital cardiac defects in dilated cardiomyopathy]. | HISTORY AND OUTPATIENT INVESTIGATION: A 61-year-old woman presented with a six-month history of chest pain and shortness of breath on normal activity. The past medical history included hypertension treated with ACE inhibitors. While still an outpatient a diagnosis was made of cardiomyopathy with left atrial and ventricular dilatation, systolic and diastolic heart failure, moderate mitral valve regurgitation and newly documented atrial fibrillation.</AbstractText>Right heart catheterization was carried out via the right femoral vein. The inferior vena cava was found to be on the left, none on the right. Venous inflow was via a dilated hemiazygos vein, a persistent left superior vena cava and a markedly dilated coronary sinus into the right atrium. The hepatic veins were also directly connected to the right atrium, as was shown by retrograde perfusion during a venogram. Coronary heart disease was excluded by angiography, but a right heart catheterization was not possible because of the atypical venous connections. Ultrasound examination revealed abdominal situs inversus and polysplenia. Magnetic resonance imaging of the thorax demonstrated bilateral bilobar lungs and bilateral hyparterial bronchi.</AbstractText><AbstractText Label="DIAGNOSIS, TREATMENT AND COURSE" NlmCategory="METHODS">Heterotaxia with anomalous systemic veins and visceral defects was revealed during a diagnostic work-up, which was indicated by the finding of a dilated cardiomyopathy with chronic atrial fibrillation, moderate mitral valve regurgitation and arterial hypertension. Arterial hypertension and heart failure were successfully treated by medication. Attempts at rhythm control were unsuccessful. Safety measures were established to prevent thromboembolic complications and endocarditis.</AbstractText>Congenital anomalies of the systemic veins in adults are often discovered incidentally, because they are usually asymptomatic. They may cause diagnostic and therapeutic difficulties in cardiology, phlebology and surgery. These anomalies may increase the risk of thrombotic and thrombembolic events. Together with polysplenia and situs inversus they are phenotypical components of heterotaxia. They may have various clinical consequences and may occur spontaneously or may be familial.</AbstractText> |
8,736 | Assessment, significance and mechanism of ventricular electrical instability after myocardial infarction. | The mechanism of reentrant tachycardia was established nearly a century ago, but the relationships between myocardial infarction and predisposition to sudden death were not unravelled until much later. In the latter half of the twentieth century many studies sought to ascertain what variables were predictive of death following myocardial infarction. Approximately one half of all deaths during the year following myocardial infarction are sudden and due to ventricular tachycardia (VT) or ventricular fibrillation (VF). We aimed to utilise non-invasive signal-averaging, along with programmed electrical stimulation of the heart, to determine whether one could predict spontaneous ventricular tachycardia and sudden death late after myocardial infarction. The sensitivity of ventricular electrical instablility (inducible ventricular tachycardia or fibrillation) as a predictor of instantaneous death or spontaneous VT was 86%, and the specificity was 83%. When other variables (delayed ventricular activation at signal-averaging, ejection fraction at gated heart pool scan, ventricular ectopic activity at ambulatory monitoring and exercise testing) were taken into account, inducible VT at electrophysiological study was the single best predictor of spontaneous VT and sudden cardiac death after myocardial infarction. The Westmead studies of Uther et al. in the decade or so from 1980 established programmed stimulation as the best predictor of sudden death after myocardial infarction. Subsequent studies by others have demonstrated a survival advantage of defibrillator implantation in patients with low ejection fraction (and inducible ventricular tachycardia) after myocardial infarction. |
8,737 | [Atrial electrical, contractile and structural remodeling induced by short-term atrial tachycardia in a canine model]. | To evaluate atrial remodeling induced by short term pacing in a canine model.</AbstractText>Transvenous lead was inserted into the right atrial appendage of anesthetized mongrel dogs and paced for 5 hours at 450 bpm (n=12). Effective refractory period (ERP) and P-wave duration were measured before and post pacing and left ventricular pressure was monitored during the procedure. Echocardiography was performed to observe the presence or absence of spontaneous echo contrast and to assess the effect of rapid atrial pacing on atrial function. All measurements were obtained in sinus rhythm. Histology of the myocardium in left atrial trabeculae and appendages was examined by electron microscopy.</AbstractText>Compared to pre-pacing status, ERP was significantly reduced [(87.27 +/- 16.35) ms vs. (113.27 +/- 11.99) ms, P<0.01] at a cycle length of 300 ms, P-wave duration significantly increased [(56.09 +/- 8.62) ms vs. (52.09 +/- 7.63) ms, P<0.01], the peak velocity of atrial contraction significantly decreased [(48.92 +/- 10.80) cm/s vs. (59.25 +/- 9.37) cm/s, P<0.05] while heart rates and left ventricular pressure were not affected post five hours rapid atrial pacing. Pacing also induced significantly cellular ultrastructures changes including myofibrils loss, glycogen accumulation, mitochondria loss and swelling.</AbstractText>Short term pacing resulted in atrial electrical, contractile and structural remodeling.</AbstractText> |
8,738 | Continuous arteriovenous haemofiltration to regulate hyperkalaemia during renal transplantation: a case report. | Progressive hyperkalaemia is common in end stage renal disease patients waiting for renal transplantation. Ventricular tachycardia and ventricular fibrillation due to hyperkalaemia are life-threatening complications in these patients. In live and related renal transplant, after induction and anaesthesia, ventricular fibrillation and pulmonary oedema occurred. After immediate resuscitation by defibrillation and intravenous injection of adrenaline, the patient was put on continuous femoral arteriovenous haemofiltration (CAVH). This improved his pulmonary oedema, controlled hyperkalaemia and surgery could be completed uninterruptedly. After anaesthetising live and related kidney donor for nephrectomy, since it is not prudent to stop recipient surgery because of unforeseen complication, the authors wish to recommend CAVH as an alternative method to prevent life threatening cardiac complication of hyperkalaemia. |
8,739 | Prognostic value of the computerized ECG in Hispanics. | The prevalence and prognostic values of electrocardiogram (ECG) abnormalities in Hispanics have not been compared to other ethnicities in a large population. Despite a worse cardiovascular risk profile, the prevalence of cardiovascular disease is lower in Hispanics compared to non-Hispanics.</AbstractText>We hypothesized that ECG abnormalities were less common in Hispanics and were not as strongly associated with cardiovascular mortality.</AbstractText>45,563 ECGs ordered for usual clinical indications in a Veteran's hospital were available for analysis. 1,392 patients who died within one week of the ECG were excluded. Demographic characteristics were recorded and the population was followed for an average of 7.5 years using the California Death Index. The presence of baseline ECG characteristics were recorded and analyzed using the GE/Marquette computerized ECG system. Age, sex and heart rate adjusted Cox hazard ratio analyses were performed.</AbstractText>Being Hispanic was associated with lower cardiovascular death, with a hazard ratio (HR) of 0.76 (95% CI 0.65-0.89). Findings such as atrial fibrillation, presence of Q-waves, left ventricular hypertrophy (LVH), upright T-waves in aortic valve replacement (aVR) and cardiac Infarction Injury Scores > 6 were significantly less prevalent in Hispanics than in non-Hispanics. These findings were similarly associated with increased cardiovascular mortality in both groups, each with a HR of approximately 2.</AbstractText>The lower prevalence of ECG characteristics associated with coronary heart disease, atrial fibrillation and left ventricular hypertrophy support prior observations that cardiovascular disease is less prevalent in the Hispanic population. These findings, however, are similarly associated with increased mortality compared to non-Hispanics.</AbstractText> |
8,740 | Clinical characteristics and outcomes of hypertrophic cardiomyopathy in Taiwan--a tertiary center experience. | Most information concerning hypertrophic cardiomyopathy has been derived from western countries and Japan.</AbstractText>Patients with hypertrophic cardiomyopathy in Taiwan may have a distinct morphology and clinical picture.</AbstractText>Information from 163 consecutive patients with hypertrophic cardiomyopathy at a medical center in Taiwan from 1990 through 2005 was retrospectively collected. The diagnosis of hypertrophic cardiomyopathy required echocardiographic demonstration of left ventricular hypertrophy (wall thickness >or= mm during diastole) in a specific region or with diffuse distribution. Follow-up information was obtained from medical records.</AbstractText>Among 163 patients (male, 52%), the mean follow-up period was 5.3 +/- 4.1 years. Men had nearly a threefold increase in prevalence of apical hypertrophic cardiomyopathy (23.8% vs. 8.9%, p = 0.03), younger onset of initial evaluation (57.2 +/- 12.9 vs. 64.8 +/- 11.3, p < 0.001), and lower prevalence of hypertrophic obstructive cardiomyopathy (33.3% vs. 63.3%, p < 0.001) compared to women. Fifty-eight patients (35.6%) experienced cardiovascular events, of which pulmonary edema and paroxysmal atrial fibrillation were the most common (19.7% and 12.3%, respectively). The annual cardiovascular mortality rate was 0.8%. In multivariate analysis, left ventricular outflow obstruction [odds ratio (OR): 4.92, p = 0.001], atrial fibrillation (OR: 3.53, p = 0.014), and female gender (OR: 2.99, p = 0.043) were independent predictors of mortality.</AbstractText>Hypertrophic cardiomyopathy did not significantly increase cardiovascular mortality rate, but over one-third of patients with hypertrophic cardiomyopathy experienced cardiovascular events. High prevalence of left ventricular outflow obstruction especially in elderly women was observed. Left ventricular outflow obstruction, atrial fibrillation, and female gender were predictors of mortality.</AbstractText> |
8,741 | Intravenous magnesium for acute myocardial infarction. | Mortality and morbidity from acute myocardial infarction (AMI) remain high. Intravenous magnesium started early after the onset of AMI is thought to be a promising adjuvant treatment. Conflicting results from earlier trials and meta-analyses warrant a systematic review of available evidence.</AbstractText>To examine the effect of intravenous magnesium versus placebo on early mortality and morbidity.</AbstractText>We searched CENTRAL (The Cochrane Library Issue 3, 2006), MEDLINE (January 1966 to June 2006) and EMBASE (January 1980 to June 2006), and the Chinese Biomedical Disk (CBM disk) (January 1978 to June 2006). Some core Chinese medical journals relevant to the cardiovascular field were hand searched from their starting date to the first-half year of 2006.</AbstractText>All randomized controlled trials that compared intravenous magnesium with placebo in the presence or absence of fibrinolytic therapy in addition to routine treatment were eligible if they reported mortality and morbidity within 35 days of AMI onset.</AbstractText>Two reviewers independently assessed the trial quality and extracted data using a standard form. Odds ratio (OR) were used to pool the effect if appropriate. Where heterogeneity of effects was found, clinical and methodological sources of this were explored.</AbstractText>For early mortality where there was evidence of heterogeneity, a fixed-effect meta-analysis showed no difference between magnesium and placebo groups (OR 0.99, 95%CI 0.94 to 1.04), while a random-effects meta-analysis showed a significant reduction comparing magnesium with placebo (OR 0.66, 95% CI 0.53 to 0.82). Stratification by timing of treatment (< 6 hrs, 6+ hrs) reduced heterogeneity, and in both fixed-effect and random-effects models no significant effect of magnesium was found. In stratified analyses, early mortality was reduced for patients not treated with thrombolysis (OR=0.73, 95% CI 0.56 to 0.94 by random-effects model) and for those treated with less than 75 mmol of magnesium (OR=0.59, 95% CI 0.49 to 0.70) in the magnesium compared with placebo groups.Meta-analysis for the secondary outcomes where there was no evidence of heterogeneity showed reductions in the odds of ventricular fibrillation (OR=0.88, 95% CI 0.81 to 0.96), but increases in the odds of profound hypotension (OR=1.13, 95% CI 1.09 to 1.19) and bradycardia (OR=1.49, 95% CI 1.26 to 1.77) comparing magnesium with placebo. No difference was observed for heart block (OR=1.05, 95% CI 0.97-1.14). For those outcomes where there was evidence of heterogeneity, meta-analysis with both fixed-effect and random-effects models showed that magnesium could decrease ventricular tachycardia (OR=0.45, 95% CI 0.31 to 0.66 by fixed-effect model; OR=0.40, 95% CI 0.19 to 0.84 by random-effects model) and severe arrhythmia needing treatment or Lown 2-5 (OR=0.72, 95% CI 0.60 to 0.85 by fixed-effect model; OR=0.51, 95% CI 0.33 to 0.79 by random-effects model) compared with placebo. There was no difference on the effect of cardiogenic shock between the two groups.</AbstractText><AbstractText Label="AUTHORS' CONCLUSIONS" NlmCategory="CONCLUSIONS">Owing to the likelihood of publication bias and marked heterogeneity of treatment effects, it is essential that the findings are interpreted cautiously. From the evidence reviewed here, we consider that: (1) it is unlikely that magnesium is beneficial in reducing mortality both in patients treated early and in patients treated late, and in patients already receiving thrombolytic therapy; (2) it is unlikely that magnesium will reduce mortality when used at high dose (>=75 mmol); (3) magnesium treatment may reduce the incidence of ventricular fibrillation, ventricular tachycardia, severe arrhythmia needing treatment or Lown 2-5, but it may increase the incidence of profound hypotension, bradycardia and flushing; and (4) the areas of uncertainty regarding the effect of magnesium on mortality remain the effect of low dose treatment (< 75 mmol) and in patients not treated with thrombolysis.</AbstractText> |
8,742 | Out of the guidelines: should an intracardiac defibrillator be implanted in patients with recurrent early ventricular fibrillation due to recurrent acute myocardial infarction? | We report the case of a patient admitted to the hospital on two different occasions, separated by a time interval of 12 years, with the same clinical picture: acute anterior myocardial infarction complicated by early ventricular fibrillation. The patient was successfully resuscitated because, in both circumstances, he was 'lucky' to arrive at hospital within a few minutes of the onset of chest pain, and to have ventricular fibrillation in the Emergency Department. The issue of intracardiac defibrillator implantation, despite this situation is not contemplated in the current guidelines (left ventricular ejection fraction was preserved), is discussed here. |
8,743 | Sudden death in a patient with lamin A/C gene mutation and near normal left ventricular systolic function. | Mutations in the lamin A/C gene seem to be important aetiological factors in familial DCM. Heart disease caused by lamin A/C gene mutations is characterised by conduction system disorders with the need for permanent pacemaker implantations, atrial fibrillation, severe heart failure, and increased risk for sudden cardiac death. We described an asymptomatic 28-year-old man with a R190W lamin A/C gene mutation and mild left ventricular enlargement and near normal left ventricular ejection fraction who suffered from sudden cardiac death during sleeping. His electrocardiogram did not show conduction system disease and the most remarkable finding was a progressive decrease in voltage, which may be a marker of disease progression. The case study's mother had a similar phenotype to this and also had died suddenly. Sudden cardiac death in some lamin A/C gene mutations may occur even before the development of severe left ventricular dysfunction and implantable cardioverter-defibrillator should be early considered. |
8,744 | Cytokines, interstitial collagen and ventricular remodelling in dilated cardiomyopathy. | Dilated cardiomyopathy (DCM) is associated with myocardial fibrosis, and proinflammatory cytokines may play a role in this.</AbstractText>N-terminal type I and III procollagen propeptides (PINP, PIIINP) and cross-linked telopeptide of type I collagen (ICTP) were measured from serum samples of 73 patients with DCM and 56 age and sex matched controls. Circulating cytokine levels were determined in DCM patients.</AbstractText>Serum levels of PINP and PIIINP were lower in patients than in controls (p<0.05 and p=0.001). In patients with DCM, the levels of PIIINP and ICTP correlated significantly with each other (p<0.01), and the proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6), correlated positively with ICTP (p<0.001, p<0.05), PIIINP/PINP ratio (p<0.05, p<0.01) and left atrial size (p<0.01, p<0.05). Presence of atrial fibrillation was associated with lower serum PINP level and higher PIIINP/PINP ratio (p<0.05).</AbstractText>Our results suggest that interstitial myocardial collagen metabolism is altered in DCM patients and regulated by proinflammatory cytokines. These changes in collagen metabolism are associated with presence of atrial fibrillation, but do not reflect left ventricular remodelling. Treatment with beta-blockers and inhibitors of the renin angiotensin aldosterone system seem to effectively inhibit overall type I and III collagen syntheses.</AbstractText> |
8,745 | Ventricular fibrillation after a hymenoptera sting. | A 54-year-old male, who had presented 2 ventricular fibrillation (VF) episodes with post-anoxic coma and later a return to consciousness and to a sinusal rhythm after defibrillation, have been placed a ventricular intracavitary stimulator (AICD). Since all the tests including the coronarygraphy have been found normal, we have paid attention to the anamnesis revealing an Apis mellifera sting before both VF episodes, previously considered irrelevant for the absence of relevant local symptoms. Intracutaneous tests were negative to Vespula sp. and positive to A. mellifera extract at a concentration of 0.01 mug/ml. Specific IgE for A. mellifera venom presented values of 2,36 U/ml for A. mellifera and <0.35 U/ml per Vespula sp. and Polistes dominulus. The patient was then submitted to ITS with A. mellifera aqueous extract. During the RASH treatment no adverse reactions have been observed, whereas we witnessed a major adverse reaction, 3 min after the first 100 mcg maintenance dose, controlled with anti-H1 and cortisone reaction, nevertheless no reactions were observed during the 3 years the same dosage has been repeated monthly. Our case supports the hypothesis of an anaphylactic reaction as trigger of vasoconstriction in individuals affected by ventricular arrhythmia not explained with other causes such as a coronary disease, a myocardiopathy or a pharmacological toxicity. Arrhythmia can be a serious outbreak of a mediated IgE allergic reaction even without any relevant local symptoms. The diagnostics with lyophilized A. mellifera venom has been proven safe in a patient who suffered a cardiac anaphylaxis. |
8,746 | Reduction of ventricular tachyarrhythmia by treatment of atrial fibrillation in ICD patients with dual-chamber implantable cardioverter/defibrillators capable of atrial therapy delivery: the REVERT-AF Study. | The purpose of this prospective, randomized, multicentre study was to investigate whether the incidence of ventricular tachyarrhythmia can be reduced in standard implantable cardioverter/defibrillator (ICD) patients by implanting a dual-chamber ICD capable of atrial therapy delivery.</AbstractText>A Jewel AF or GEM III AT ICD (Medtronic Inc., Minneapolis, MN, USA) was implanted in 122 patients (62.3 +/- 10.5 years; 84.4% male; coronary artery disease 71.3%; left ventricular ejection fraction 39.7 +/- 13.6%; secondary ICD indication 91%). Overall, 31.2% of the patients had paroxysmal atrial fibrillation (AF)/atrial tachycardia (AT) before ICD implantation (n = 38). Implantable cardioverter/defibrillator therapies for AT/AF were activated and de-activated every 3 months in a cross-over study design. The mean follow-up was 18.5 +/- 7.7 months (6.29 +/- 2.2 cross-over/patient). Overall, there were 684 episodes of ventricular tachyarrhythmias in 48.4% of patients (n = 59). In 33.6% of patients (n = 41), 532 supraventricular tachyarrhythmias occurred. Activation of ICD therapies for AT/AF did not result in a reduction of ventricular tachyarrhythmias (P = 0.92). Patients with monomorphic ventricular tachycardias (mVTs) as index arrhythmia for ICD implantation or inducible mVTs in the electrophysiological study had the highest probability of recurrences of ventricular tachyarrhythmias.</AbstractText>For patients with standard indications for ICD therapy and no indication for cardiac pacing, a dual-chamber ICD capable of atrial tachyarrhythmia treatment offers no benefit concerning a reduction of ventricular tachyarrhythmias.</AbstractText> |
8,747 | In vitro and in vivo effects of the atrial selective antiarrhythmic compound AVE1231. | The novel compound AVE1231 was investigated in order to elucidate its potential against atrial fibrillation. In CHO cells, the current generated by hKv1.5 or hKv4.3 + KChIP2.2b channels was blocked with IC50 values of 3.6 microM and 5.9 microM, respectively. In pig left atrial myocytes, a voltage-dependent outward current was blocked with an IC50 of 1.1 microM, mainly by accelerating the time constant of decay. Carbachol-activated IKACh was blocked by AVE1231 with an IC50 of 8.4 microM. Other ionic currents, like the IKr, IKs, IKATP, ICa, and INa were only mildly affected by 10 microM AVE1231. In guinea pig papillary muscle the APD90 and the upstroke velocity were not significantly altered by 30 microM AVE1231. In anesthetized pigs, oral doses of 0.3, 1, and 3 mg/kg AVE1231 caused a dose-dependent increase in left atrial refractoriness (LAERP), associated by inhibition of left atrial vulnerability to arrhythmia. There were no effects on the ECG intervals, ventricular monophasic action potentials, or ventricular refractory periods at 3 mg/kg AVE1231 applied intravenously. In conscious goats, both AVE1231 (3 mg/kg/h iv) and dofetilide (10 microg/kg/h iv) significantly prolonged LAERP. After 72 hours of tachypacing, when LAERP was shortened significantly (electrical remodelling), the prolongation of LAERP induced by AVE1231 was even more pronounced than in sinus rhythm. In contrast, the effect of dofetilide was strongly decreased. The present data demonstrate that AVE1231 blocks early atrial K channels and prolongs atrial refractoriness with no effects on ECG intervals and ventricular repolarisation, suggesting that it is suited for the prevention of atrial fibrillation in patients. |
8,748 | Ventricular arrhythmias during left ventricular assist device support. | Left ventricular assist devices (LVADs) have been used effectively as a "bridge" to cardiac transplantation and as destination therapy in patients with advanced heart failure. Ventricular arrhythmias (VAs) have been reported to occur in LVAD-supported patients, although their incidence, risk factors, and clinical significance have not been characterized. In this study, 111 patients who received LVAD support as a bridge to cardiac transplantation at the University of Pittsburgh Medical Center from January 1987 to June 2001 were evaluated. Clinically significant VA was defined as ventricular fibrillation, sustained ventricular tachycardia, or nonsustained ventricular tachycardia with symptoms requiring antiarrhythmic therapy. Patients were grouped on the basis of the presence or absence of VAs. VAs occurred in 24 patients (22%) during device support. Ischemic heart disease was the cause of heart failure in 71% of patients (17 of 24) in the VA group and 45% of patients (39 of 87) in the group without VAs (p <0.05). The mortality rate was significantly higher (p <0.001) during LVAD support in the group with VAs (33%) compared with the group without VAs (18%). In the group with VAs, the early (<or=1 week) occurrence of VAs was associated with a significantly higher (p <0.001) mortality rate (54%) compared with late (>1 week) occurrence (9%). In conclusion, although clinically significant VAs occur in patients with heart failure receiving LVAD support, the overall incidence is low. VAs are more frequent in patients with ischemic heart failure, and their occurrence is associated with greater mortality. The occurrence of VAs early after LVAD implantation, in particular, predicts a higher mortality rate. |
8,749 | Ventricular tachycardia in non-compaction of left ventricle: is this a frequent complication? | Isolated left ventricular non-compaction is the result of incomplete myocardial morphogenesis, leading to persistence of the embryonic myocardium. The condition is recognized by an excessively prominent trabecular meshwork and deep intertrabecular recesses of the left ventricle. Whether these intertrabecular recesses are a favorable substrate for ventricular arrhythmias is unclear. Some reports have found that the fatal ventricular arrhythmias may occur in approximately half of the patients. In this report we investigated about this association.</AbstractText>In total we evaluated a continuous series of 238 patients affected by non-compaction. Periodic Holter monitoring was performed every 6 months for 4 years. Only 11 patients had documented ventricular tachycardia, which was sustained in two cases and non-sustained in nine. In no cases we observed ventricular fibrillation.</AbstractText>Non-compaction alone does not seem to be a risk factor for malignant ventricular arrhythmias.</AbstractText> |
8,750 | Reverse electrical remodeling of the atria post cardioversion in patients who remain in sinus rhythm assessed by signal averaging of the P-wave. | This study was designed to determine whether the signal-averaged electrocardiogram of the P-wave (SAPW) is an independent predictor of recurrence of atrial fibrillation (AF) post cardioversion (CV), and to assess atrial remodeling using SAPW.</AbstractText>There are limited electrophysiologic data to predict the recurrence of AF post-CV. The electrical remodeling that occurs post-CV is poorly understood.</AbstractText>Sixty-four patients with persistent AF undergoing CV were prospectively enrolled. SAPW parameters were measured the day of CV and repeated at 1 month. These SAPW parameters were compared to other baseline indices for the recurrence of AF.</AbstractText>Sixty patients (94%) had successful CV. At 1 month, 22 (37%) maintained sinus rhythm (SR). The SAPW total duration decreased significantly in those who remained in SR (159 ms +/- 19 to 146 ms +/- 17; P < 0.0001). Only the duration of AF (46 +/- 50 days vs 147 +/- 227 days, P = 0.03) and the presence of left ventricular hypertrophy (LVH, 12% vs 65%, P = 0.0006) were significantly associated with recurrence of AF. Atrial size strongly correlated with the SAPW duration in patients who remained in SR (R(2)= 0.67, P = 0.003) but not in those who returned to AF (R(2)= 0.11, P = 0.65).</AbstractText>Atrial electrical reverse remodeling occurs in patients with AF who maintain SR post-CV. This remodeling is likely inversely related to the duration of AF and LVH. SAPW duration does not predict recurrence of AF post-CV.</AbstractText> |
8,751 | [Ablation of a catecholaminergic polymorphic VT and VF originating from Purkinje fibers--a case report]. | We describe a case of a 25-year-old woman suffering from recurrent adrenergic polymorphic ventricular tachycardia (PVT). As a 14-year-old the patient suffered from recurrent episodes of syncope during exercise or emotion. On Holter monitoring unsustained runs of PVT were observed. The patient survived SCD (VF) which occurred near the hospital. An ICD was implanted and during the first year over 150 adequate discharges were present. During 9 year follow-up the patient had to have 4 ICDs replaced. She suffered from post-traumatic stress disorder syndrome due to frequent ICD shocks. After age of 23 she was admitted to our hospital and an ablation using the CARTO system was performed. No low voltage areas were observed. During the study ventricular premature beats and VT/PVT runs were observed originating from the Purkinje fibres. RF applications were delivered at those sites, during which abrupt PVT runs were present. After the ablation no ventricular arrhythmia was registered in the ICD memory during 2-year follow-up. |
8,752 | Pulmonary thromboembolism in 102 consecutive patients with chronic atrial fibrillation. Diagnostic value of echocardiography. | Little is known about the incidence and diagnosis of pulmonary thromboembolism (PE) in patients with chronic permanent atrial fibrillation (CAF). Also it has not been established if echocardiography, a diagnostic tool useful in clinical evaluation of both diseases, is of value in diagnosis of PE in CAF patients.</AbstractText>To establish the prevalence of PE among patients suffering from CAF without or with poorly controlled anticoagulation as well as to evaluate the possibility to detect PE and to assess the diagnostic role of echocardiography.</AbstractText>Prevalence of PE in a population of 102 patients (52 males and 50 females at the mean age of 68 years, range 32-88 years) admitted to hospital between January and December 2004 with diagnosis of CAF was studied retrospectively. Echocardiography-based original algorithm of PE diagnosis in such patients was analysed.</AbstractText>Among 102 patients with CAF, 20 (19%) cases of PE were diagnosed, including 12 with acute PE (APE) and 8 suffering from chronic thromboembolic pulmonary hypertension (CTEPH). Patients with CAF and APE as well as with CAF and CTEPH had increased right ventricular dimension (p=0.0002 and p=0.001, respectively), higher tricuspid pressure gradient (p=0.005 and p=0.001, respectively) and shorter pulmonary artery acceleration time (p=0.00006 and p=0.0004, respectively) estimated in echocardiography as compared to patients with CAF but without PE. Subjects with CAF and PE had also significantly decreased left ventricular dimension and better left ventricular performance.</AbstractText>A relatively high incidence of PE among patients with CAF not treated with anticoagulants or with poorly controlled anticoagulation therapy was noted. The important value of a diagnostic algorithm employing echocardiography in a diagnosis of clinically significant APE and CTEPH in this group of patients was also shown.</AbstractText> |
8,753 | Contemporary catheter ablation of arrhythmias in geriatric patients: patient characteristics, distribution of arrhythmias, and outcome. | Catheter ablation is a treatment of first choice for many arrhythmias. Data in geriatric patients are still limited, mostly focusing on single arrhythmia types. The aim of the study was to investigate characteristics of contemporary ablation therapy in the very elderly, focusing on patient characteristics, arrhythmia spectrum, and outcome in a large cohort.</AbstractText>We studied 131 consecutive patients aged 80 and older (mean age 83 +/- 3) undergoing ablation for any indication from 1998 until 2004. Sixty-eight patients (52%) had structural heart disease. Most common indications were typical atrial flutter (54%), atrioventricular nodal re-entrant tachycardia (AVNRT) (22%), and atrial fibrillation (AF) (18%). Patients with structural heart disease had more often atrial flutter (72 vs. 35%, P < 0.001) and less AVNRT (7 vs. 38%, P < 0.001) than those without structural heart disease. In almost all patients with AF, ventricular rate control was achieved by elimination of atrioventricular conduction and pacemaker implantation. Success rate exceeded 97% for all ablation types. There was one major complication (0.8%), a stroke after isthmus ablation.</AbstractText>Almost half of the very elderly patients undergoing ablation have structural heart disease. Indications have changed significantly in recent years, typical atrial flutter is nowadays the predominant indication. The arrhythmia spectrum differs significantly between patients with and without structural heart disease. Regardless of the presence or absence of structural heart disease, success is excellent. Catheter ablation is an excellent therapy option for geriatric patients with arrhythmias.</AbstractText> |
8,754 | Effects of garlic on defibrillation efficacy.<Pagination><StartPage>143</StartPage><EndPage>144</EndPage><MedlinePgn>143-4</MedlinePgn></Pagination><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Sungnoon</LastName><ForeName>Rattapong</ForeName><Initials>R</Initials></Author><Author ValidYN="Y"><LastName>Shinlapawittayatorn</LastName><ForeName>Krekwit</ForeName><Initials>K</Initials></Author><Author ValidYN="Y"><LastName>Chattipakorn</LastName><ForeName>Siriporn C</ForeName><Initials>SC</Initials></Author><Author ValidYN="Y"><LastName>Chattipakorn</LastName><ForeName>Nipon</ForeName><Initials>N</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D003160">Comparative Study</PublicationType><PublicationType UI="D016422">Letter</PublicationType><PublicationType UI="D013485">Research Support, Non-U.S. Gov't</PublicationType></PublicationTypeList><ArticleDate DateType="Electronic"><Year>2007</Year><Month>04</Month><Day>16</Day></ArticleDate></Article><MedlineJournalInfo><Country>Netherlands</Country><MedlineTA>Int J Cardiol</MedlineTA><NlmUniqueID>8200291</NlmUniqueID><ISSNLinking>0167-5273</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D010936">Plant Extracts</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000818" MajorTopicYN="N">Animals</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D004554" MajorTopicYN="Y">Electric Countershock</DescriptorName><QualifierName UI="Q000379" MajorTopicYN="N">methods</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D005737" MajorTopicYN="Y">Garlic</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D007262" MajorTopicYN="N">Infusions, Intravenous</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D010936" MajorTopicYN="N">Plant Extracts</DescriptorName><QualifierName UI="Q000627" MajorTopicYN="N">therapeutic use</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D013552" MajorTopicYN="N">Swine</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D014693" MajorTopicYN="N">Ventricular Fibrillation</DescriptorName><QualifierName UI="Q000188" MajorTopicYN="Y">drug therapy</QualifierName><QualifierName UI="Q000503" MajorTopicYN="N">physiopathology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="received"><Year>2006</Year><Month>12</Month><Day>14</Day></PubMedPubDate><PubMedPubDate PubStatus="accepted"><Year>2007</Year><Month>1</Month><Day>3</Day></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2007</Year><Month>4</Month><Day>17</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2008</Year><Month>9</Month><Day>16</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2007</Year><Month>4</Month><Day>17</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">17434624</ArticleId><ArticleId IdType="doi">10.1016/j.ijcard.2007.01.083</ArticleId><ArticleId IdType="pii">S0167-5273(07)00568-2</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">17434005</PMID><DateCompleted><Year>2007</Year><Month>09</Month><Day>26</Day></DateCompleted><DateRevised><Year>2007</Year><Month>11</Month><Day>15</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">1092-9126</ISSN><JournalIssue CitedMedium="Print"><PubDate><Year>2007</Year></PubDate></JournalIssue><Title>Seminars in thoracic and cardiovascular surgery. Pediatric cardiac surgery annual</Title><ISOAbbreviation>Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu</ISOAbbreviation></Journal>Evolving anatomic and electrophysiologic considerations associated with Fontan conversion. | The principles of Fontan conversion with arrhythmia surgery are to restore the cardiac anatomy by converting the original atriopulmonary connection to a total cavopulmonary artery extracardiac connection and treat the underlying atrial arrhythmias. Successful outcomes of this procedure are dependent on a thorough understanding of several factors: the patient's fundamental diagnosis of single-ventricle anatomy, the resultant cardiac configuration from the original atriopulmonary Fontan connection, right atrial dilatation that leads to atrial flutter or fibrillation, and associated congenital cardiac anomalies. The purpose of this article is to present some of the more challenging anatomic and electrophysiologic problems we have encountered with Fontan conversion and arrhythmia surgery and the innovative solutions we have used to treat them. The cases reviewed herein include: takedown of a Bjork-Fontan modification, right ventricular hypertension and tricuspid regurgitation after atriopulmonary Fontan for pulmonary atresia and intact ventricular septum, takedown of atrioventricular valve isolation patch for right-sided maze procedure, resultant hemodynamic considerations leading to intraoperative pulmonary vein stenosis after Fontan conversion, unwanted inferior vena cava retraction during the extracardiac connection, right atrial cannulation in the presence of a right atrial clot, distended left superior vena cava causing left pulmonary vein stenosis, dropped atrial septum, and the modified right-sided maze procedure for various single-ventricle pathology. Since 1994 we have performed Fontan conversion with arrhythmia surgery on 109 patients with a 0.9% mortality rate. We attribute our program's success in no small measure to the strong collaborative efforts of the cardiothoracic surgery and cardiology teams. |
8,755 | The incidence and significance of emesis associated with out-of-hospital cardiac arrest. | Studies have suggested that emesis may occur in up to a third of cardiac arrest patients. The goal of this investigation was to characterize the frequency, timing, and outcome association of emesis in persons suffering out-of-hospital cardiac arrest in order to understand the role and care-implications of emesis better.</AbstractText>We conducted a cohort study of persons 18 years and over suffering non-traumatic out-of-hospital cardiac arrests who received attempted resuscitation by paramedics in the study community from January 1, 2004 through December 31, 2005 (n=1009). The presence and timing of emesis were determined by paramedics and recorded on the Emergency Medical Services report form. We used logistic regression analyses to assess whether emesis was independently associated with survival to hospital discharge.</AbstractText>The presence or absence of emesis was documented in 76% (1009/1333) of cases. Emesis was present in 32% (318/1009). Two-thirds (208/312) of emesis occurred prior to EMS arrival; 28% (88/312) of episodes occurred between EMT arrival and intubation; and 4% (13/312) occurred after intubation. After adjustment for potential confounders, the presence of emesis was associated with a decreased odds of survival to hospital discharge among all-rhythm arrest (Odds ratio (OR)=0.50 [0.28-0.89]) and ventricular fibrillation arrest (OR=0.52 [0.27-0.98]).</AbstractText>Given the frequency of emesis, the potential that some portion of emesis may be related to care, and the adverse association between emesis and survival, approaches that treat or prevent emesis better may improve the chances of survival following out-of-hospital cardiac arrest.</AbstractText> |
8,756 | [Lethal streptococcal toxic shock syndrome in pediatrics. Presentation of 3 cases]. | Three cases of children admitted to the Pediatric Intensive Medicine Unit in the months of February to March 2004 with the diagnosis of streptococcal toxic shock syndrome are presented. Two were under 2 years of age and the initial symptoms suggested viriasis. They evolved towards septic shock with early multiorganic failure and then death due to massive hemoptysis, ventricular fibrillation due to hyperkaliemia. Streptococcus pyogenes with serotypes M1T1 was isolated in all the cases and the patients had the clinical criteria of streptococcal toxic shock syndrome. Their course was unfavorable in spite of the resuscitation steps, early antibiotic treatment and artificial support of the different organic failures. We stress the rareness of the cases, early age, its appearance in a short period of time, its sudden onset and the null response to treatment initiated. |
8,757 | Minimally invasive cardiopulmonary bypass: does it really change the outcome? | Many innovative cardiopulmonary bypass (CPB) systems have recently been proposed by the industry. With few differences, they all share a philosophy based on priming volume reduction, closed circuit with separation of the surgical field suction, centrifugal pump, and biocompatible circuit and oxygenator. These minimally invasive CPB (MICPB) systems are intended to limit the deleterious effects of a conventional CPB. However, no evidence exists with respect to their effectiveness in improving the postoperative outcome in a large population of patients. This study aimed to verify the clinical impact of an MICPB in a large population of patients undergoing coronary artery revascularization.</AbstractText>We conducted a retrospective analysis of 1,663 patients treated with an MICPB. The control group (conventional CPB) was extracted from a series of 2,877 patients according to a propensity score analysis.</AbstractText>Patients receiving an MICPB had a shorter intensive care unit (ICU) stay, had lower peak postoperative serum creatinine and bilirubin levels, and suffered less postoperative blood loss. Within a multivariable model, MICPB is independently associated with lower rates of atrial fibrillation (odds ratio [OR] 0.83, 95% confidence interval [CI] 0.69 to 0.99) and ventricular arrhythmias (OR 0.45, 95% CI 0.28 to 0.73) and with higher rates of early discharge from the ICU (OR 1.31, 95% CI 1.06 to 1.6) and from the hospital (OR 1.46, 95% CI 1.18 to 1.8). Hospital mortality did not differ between groups.</AbstractText>MICPBs are associated with reduced morbidity. However, these results will need to be confirmed in a large, prospective, randomized, controlled trial.</AbstractText> |
8,758 | [Familial short QT syndrome]. | Short QT syndrome is a newly described cardiologic entity which associates a short OT interval (QT and QTc < or = 300 ms) on the surface ECG to a high risk of syncope or sudden death due to malignant ventricular arrhythmia. This extremely rare syndrome affects mainly young adults or infants and has a wide clinical expression. It is frequently associated with atrial fibrillation. Mutations in 3 different genes KCNQ1, KCNH2, and KCNJ2, all encoding cardiac ionic potassium channels have been identified in affected patients. The clinical spectrum is very wide ranging from asymptomatic carriers to syncope or sudden death. It is an autosomal dominant transmission. Expression studies have shown a gain of function and a shortening of the action potential duration thus explaining the short OT interval. At electrophysiologic study, atrial and ventricular refractory periods are short, and ventricular fibrillation inducible in the majority of patients. As of today, automatic implantable defibrillator is the only effective treatment for the prevention of sudden death in the short QT syndrome. |
8,759 | P wave dispersion in patients with rheumatoid arthritis: its relation with clinical and echocardiographic parameters. | P wave dispersion (PWD) is a sign for the prediction of atrial fibrillation (AF). The aim of this study was to assess P wave dispersion and its relation with clinical and echocardiographic parameters in patients with rheumatoid arthritis (RA). Thirty RA patients (mean age 49 +/- 10 years) and 27 healthy controls (mean age 47 +/- 8 years) were included in the study. We performed electrocardiography and Doppler echocardiography on patients and controls. Maximum and minimum P wave duration were obtained from electrocardiographic measurements. PWD defined as the difference between maximum and minimum P wave duration was also calculated. Maximum P wave duration and PWD was higher in RA patients than controls (P = 0.031 and P = 0.001, respectively). However, there was no significant difference in minimum P wave duration between the two groups (P = 0.152). There was significant correlation between PWD and disease duration (r = 0.375, P = 0.009) and isovolumetric relaxation time (r = 0.390, P = 0.006). P wave duration and PWD was found to be higher in RA patients than healthy control subjects. PWD is closely associated with disease duration and left ventricular (LV) diastolic dysfunction. |
8,760 | Limiting sarcolemmal Na+ entry during resuscitation from ventricular fibrillation prevents excess mitochondrial Ca2+ accumulation and attenuates myocardial injury. | intracellular Na+ accumulation during ischemia and reperfusion leads to cytosolic Ca2+ overload through reverse-mode operation of the sarcolemmal Na+ -Ca2+ exchanger. Cytosolic Ca2+ accumulation promotes mitochondrial Ca2+ (Ca2+ m) overload, leading to mitochondrial injury. We investigated whether limiting sarcolemmal Na+ entry during resuscitation from ventricular fibrillation (VF) attenuates Ca2+ m overload and lessens myocardial dysfunction in a rat model of VF and closed-chest resuscitation.</AbstractText>hearts were harvested from 10 groups of 6 rats each representing baseline, 15 min of untreated VF, 15 min of VF with chest compression given for the last 5 min (VF/CC), and 60 min postresuscitation (PR). VF/CC and PR included four groups each randomized to receive before starting chest compression the new NHE-1 inhibitor AVE4454B (1.0 mg/kg), the Na+ channel blocker lidocaine (5.0 mg/kg), their combination, or vehicle control. The left ventricle was processed for intracellular Na+ and Ca2+ m measurements.</AbstractText>limiting sarcolemmal Na+ entry attenuated cytosolic Na+ increase during VF/CC and the PR phase and prevented Ca2+ m overload yielding levels that corresponded to 77% and 71% of control hearts at VF/CC and PR, without differences among specific Na+ -limiting interventions. Limiting sarcolemmal Na+ entry attenuated reductions in left ventricular compliance during VF and prompted higher mean aortic pressure (110 +/- 7 vs. 95 +/- 11 mmHg, P < 0.001) and higher cardiac work index (159 +/- 34 vs. 126 +/- 29 g x m x min(-1) x kg(-1), P < 0.05) with lesser increases in circulating cardiac troponin I at 60 min PR.</AbstractText>Na+ -limiting interventions prevented excess Ca2+ m accumulation induced by ischemia and reperfusion and ameliorated myocardial injury and dysfunction.</AbstractText> |
8,761 | How to diagnose diastolic heart failure: a consensus statement on the diagnosis of heart failure with normal left ventricular ejection fraction by the Heart Failure and Echocardiography Associations of the European Society of Cardiology. | Diastolic heart failure (DHF) currently accounts for more than 50% of all heart failure patients. DHF is also referred to as heart failure with normal left ventricular (LV) ejection fraction (HFNEF) to indicate that HFNEF could be a precursor of heart failure with reduced LVEF. Because of improved cardiac imaging and because of widespread clinical use of plasma levels of natriuretic peptides, diagnostic criteria for HFNEF needed to be updated. The diagnosis of HFNEF requires the following conditions to be satisfied: (i) signs or symptoms of heart failure; (ii) normal or mildly abnormal systolic LV function; (iii) evidence of diastolic LV dysfunction. Normal or mildly abnormal systolic LV function implies both an LVEF > 50% and an LV end-diastolic volume index (LVEDVI) <97 mL/m(2). Diagnostic evidence of diastolic LV dysfunction can be obtained invasively (LV end-diastolic pressure >16 mmHg or mean pulmonary capillary wedge pressure >12 mmHg) or non-invasively by tissue Doppler (TD) (E/E' > 15). If TD yields an E/E' ratio suggestive of diastolic LV dysfunction (15 > E/E' > 8), additional non-invasive investigations are required for diagnostic evidence of diastolic LV dysfunction. These can consist of blood flow Doppler of mitral valve or pulmonary veins, echo measures of LV mass index or left atrial volume index, electrocardiographic evidence of atrial fibrillation, or plasma levels of natriuretic peptides. If plasma levels of natriuretic peptides are elevated, diagnostic evidence of diastolic LV dysfunction also requires additional non-invasive investigations such as TD, blood flow Doppler of mitral valve or pulmonary veins, echo measures of LV mass index or left atrial volume index, or electrocardiographic evidence of atrial fibrillation. A similar strategy with focus on a high negative predictive value of successive investigations is proposed for the exclusion of HFNEF in patients with breathlessness and no signs of congestion. The updated strategies for the diagnosis and exclusion of HFNEF are useful not only for individual patient management but also for patient recruitment in future clinical trials exploring therapies for HFNEF. |
8,762 | Implantable cardioverter-defibrillator shocks increase T-wave alternans. | While implantable defibrillator shocks save lives, shock can lead to ventricular arrhythmias. However, the mechanism of shock-related proarrhythmia remains unclear. We evaluated the impact of ICD shock on repolarization instability, a factor associated with ventricular arrhythmogenesis.</AbstractText>Sixty-five patients with ICDs underwent ambulatory ECG monitoring during defibrillation testing 3 months postimplant. TWA was analyzed continuously in the time domain during baseline, sedated, and post-shock states. RR, QRS, and QT intervals and catecholamines were also measured continuously. Adequate pre- and post-shock Holter data were recorded in 55 patients, 48 male, mean 64 +/- 12 years, 50 with coronary disease, 48 with prior spontaneous or induced arrhythmia. TWA significantly increased after shock, from 9.6 +/- 0.5 to 11.9 +/- 0.6 microV, as did QRS duration, epinephrine, and norepinephrine levels, compared with sedated and baseline states. RR intervals decreased minimally. TWA changes with shock were not associated with RR or QRS duration changes, but were associated with changes in epinephrine.</AbstractText>ICD shock, even in the sedated state, increases repolarization instability as measured by TWA, an effect mediated in part by sympathetic stimulation. This association between shock and TWA may have important mechanistic and clinical implications for optimization of defibrillation therapy.</AbstractText> |
8,763 | Estimation of microinhomogeneity of conduction impairment by wavelet analysis during early phase of myocardial ischemia in pigs. | Ventricular fibrillation (VF) is most frequent in the very early phase in acute coronary occlusion, and is triggered by the re-entrant mechanism in this phase. An inhomogeneous conduction in the ischemic myocardium would be substrates for re-entry. The aim of this study was to examine the relationship between the severity of irregularities of the QRS complex and VF. Eleven pigs were analyzed, and the heart was fixed in the pericardial cradle. Ag-AgCl bipolar electrodes were fixed on the epicardium in ischemic and non-ischemic regions. The proximal portion of the left anterior descending coronary artery was occluded for one hour. Electrocardiograms (ECGs) were continuously recorded on a magnetic tape, and wavelet analysis was performed on signal-averaged ECG (25 beats) every 60 sec after the experiment. The number of local maxima (N) and the duration between the first and the last local maximum (D) were automatically measured. N and D significantly increased in the ischemic area, but not in the non-ischemic area. N and D increased approximately twofold just before the occurrence of VF in 8 fibrillated pigs (p<0.01, each). There were significant positive linear relationships between the rate of increase in N and D to VF and basal heart rate before coronary occlusion (r=0.90, p <0.01 in N, r=0.84, p <0.01 in D at 160 Hz). These results suggest that there would be a threshold inhomogeneous conduction for the occurrence of VF and an increase in heart rate would accelerate the inhomogeneous conduction in acute myocardial ischemia. |
8,764 | [Prevention of ischemic stroke in middle aged patients with atrial fibrillation. Effect of sinus rhythm maintenance, aspirin, warfarin, and simvastatin]. | Patients (n=263, age 49-64 years) with persistent nonvalvular atrial fibrillation were subjected to controlled treatment aimed at restoration and maintenance of sinus rhythm (n=134) or slowing of rate of ventricular contractions. Efficacy of complementary use of combination of simvastatin with aspirin, warfarin and aspirin for prevention of ischemic stroke was assessed in both of these strategies. First strategy, supplemented with combination of simvastatin and aspirin prevented ischemic stroke and lethal outcome most successfully, while the use of warfarin was unexpectedly associated with comparative elevation of risk of ischemic stroke. It is impossible to exclude that long term administration of warfarin in strategy of sinus rhythm maintenance attenuated advantages of normal rhythm in relation of lowering of stroke risk in AFFIRM study and other similar works. Contrary to known cardio-embolic mechanism of cerebral embolism in permanent atrial fibrillation main aim of the treatment in successful sinus rhythm maintenance may become prevention of arterio-arterial emboli. |
8,765 | [Clinical features of thyrotoxic heart disease: analysis of 75 cases]. | To investigate the clinical features of thyrotoxic heart disease.</AbstractText>The clinical data of 75 patients with thyrotoxic heart disease, 30 males and 45 females, aged 54.3 +/- 14.4 (17 approximately 84, with the course from 1 month to 30 years, were analyzed retrospectively.</AbstractText>Forty-seven of the 75 patients (63%)presented heart failure, 47 patients (63%) showed atrial fibrillation, 2 patients (3%) showed sick sinus syndrome; 48 patients (66%) showed left atrial enlargement, 31 (43%) showed left ventricular enlargement, 30 (41%) showed right atrial enlargement, 35 (47%) showed right ventricular enlargement, and 18 (25%) showed entire heart enlargement. Mitral valve regurgitation occurred in 45 patients, tricuspid regurgitation in 45, aortic valve regurgitation in 34, and pulmonary artery hypertension (with the pulmonary blood pressure of 44 +/- 7 mm Hg and LVEF of 60% +/- 19%) in 33 patients.</AbstractText>The clinical manifestations of thyrotoxic heart disease are various Thyroid function should be investigated to exclude thyrotoxic heart disease when routine treatment is ineffective in heart disease. The key point of treatment is hyperthyroidism.</AbstractText> |
8,766 | Bivalirudin anticoagulation for cardiopulmonary bypass: an unusual case. | The standard agent used for systemic anticoagulation during cardiopulmonary bypass is heparin. Alternative methods of anticoagulation are required for patients with heparin hypersensitivity. We present the case of a patient with heparin hypersensitivity who was anticoagulated with bivalirudin during cardiopulmonary bypass for coronary artery bypass grafting. This presented unusual challenges surrounding the monitoring of anticoagulation and the method of myocardial protection. |
8,767 | Atrial fibrillation with left bundle branch block and intermittent right axis deviation during acute myocardial infarction. | Rarely the ECG shows an LBBB with changing QRS morphology and changing axis deviation. The intermittent positive aspect of the neglected lead aVR indicates an intermittent right axis deviation in the presence of complete LBBB. An additional left posterior fascicular block accompanying predivisional LBBB is the possible explanation. We describe the case of a 78-year-old Italian woman admitted to the Cardiology Unit with acute myocardial infarction and permanent atrial fibrillation. Electrocardiographic changes were observed. The ECG showed atrial fibrillation and LBBB with intermittent left axis deviation or atrial fibrillation and LBBB with intermittent right axis deviation. |
8,768 | Respiratory controversies in the critical care setting. Should all patients be treated with hypothermia following cardiac arrest? | Cardiac arrest is a common and lethal medical problem; each year more than half a million people in the United States and Canada suffer cardiac arrest treated by emergency medical personnel or in-hospital providers. Of those who survive to hospital admission or suffer in-hospital arrest, 40-60% die prior to discharge. Neurologic injury is the major source of morbidity and mortality after recovery of spontaneous circulation. Therapeutic options to prevent neurologic injury are limited, but recent randomized trials showed that moderate therapeutic hypothermia improves neurologic outcome in selected patients following cardiac arrest. Clear consensus statements recommend that unconscious adult patients with spontaneous circulation after out-of-hospital cardiac arrest should be cooled if the initial rhythm was ventricular fibrillation, and that therapeutic hypothermia should be considered for other patients (other rhythms or in-hospital arrest). However, the position that all patients should be cooled following cardiac arrest is probably too broad, given the lack of studies on patients with non-ventricular-fibrillation rhythms, in-hospital arrest, or non-cardiac causes of arrest. Further research is needed to determine the broadest application of moderate therapeutic hypothermia. |
8,769 | Is there an anatomical substrate for idiopathic paroxysmal atrial fibrillation? A case-control echocardiographic study. | Idiopathic paroxysmal atrial fibrillation (AF) occurs in patients with apparently normal heart. Its mechanisms may be complex and are poorly understood. The aim of the study was to evaluate whether patients with idiopathic AF have any structural abnormality that may explain the occurrence of AF.</AbstractText>A case-control study was undertaken including 60 consecutive patients (mean age 48 +/- 12 years; 75% men) with idiopathic AF admitted to the emergency department. Sixty sex- and age-matched healthy volunteers made up the control group. An echocardiogram was performed in all patients and volunteers to assess the left atrial (LA) and ventricular (LV) dimensions and valvular function. LV diastolic function was also evaluated by analysis of the LV inflow and pulmonary vein flow velocity patterns and tissue Doppler imaging of the mitral annulus. All AF patients showed normal echocardiographic studies with similar LV dimensions, ejection fraction, and diastolic function when compared with normal controls. However, patients with AF had larger LA dimensions (27 +/- 3 vs. 24 +/- 3 mm/m(2)), LA area (10 +/- 2 vs. 8 +/- 2 mm(2)/m(2)), and LA volume (27 +/- 9 vs. 19 +/- 6 mL/m(2)) (P < 0.05 for all). Among patients with AF, there were no differences in LA size between patients with a first episode or recurrent paroxysmal episodes.</AbstractText>Patients with idiopathic AF showed larger left atria when compared with controls, there being no differences between patients with a first episode or a recurrence. This suggests the presence of an enhanced substrate to develop idiopathic lone AF.</AbstractText> |
8,770 | Is all ventricular fibrillation the same? A comparison of ischemically induced with electrically induced ventricular fibrillation in a porcine cardiac arrest and resuscitation model. | The standard porcine cardiac arrest model uses electrical induction of ventricular fibrillation. Reported restoration of spontaneous circulation and survival rates in this model are as high as 90% for ventricular fibrillation durations of 7-10 mins, values substantially greater than rates in the clinical population (i.e., 20% to 30%). A high first shock success rate, infrequent refibrillation, and short times for restoration of spontaneous circulation are typical of the model. The purpose of this study was to determine whether ischemic induction of ventricular fibrillation in swine followed by standard advanced cardiac life support would result in short-term outcomes approximating those observed in human victims of out-of-hospital ventricular fibrillation.</AbstractText>Randomized comparative trial.</AbstractText>Translational research laboratory.</AbstractText>Domestic swine (n = 40, mean weight 40 +/- 4 kg, range 34-47 kg) of both genders.</AbstractText>Swine were instrumented and randomized to either electrical ventricular fibrillation induction or ischemic ventricular fibrillation, produced by balloon occlusion of the mid-left anterior descending coronary artery (n = 20 per group). Transthoracic impedance was measured and 30 Omega added in series for all animals. The balloon remained inflated during resuscitation efforts in ischemic ventricular fibrillation animals. After 7 mins of ventricular fibrillation, cardiopulmonary resuscitation was initiated and defibrillation was attempted 1 min later. Epinephrine and antiarrhythmics were administered as per guidelines. Resuscitation was terminated if restoration of spontaneous circulation had not occurred after 15 mins of advanced cardiac life support.</AbstractText>Although the number of countershocks required to initially terminate ventricular fibrillation was not different (electrical ventricular fibrillation 1.9 +/- 1.6, ischemic ventricular fibrillation 2.4 +/- 2.0), the refibrillation rate was higher in the ischemic ventricular fibrillation group (4.9 +/- 4 vs. 0.8 +/- 1 episodes/animal, p < .001), resulting in a greater number of shocks before restoration of spontaneous circulation (total shocks for ischemic ventricular fibrillation 9.4 +/- 5.6 vs. electrical ventricular fibrillation 2.7 +/- 2.2, p < .001). Time to restoration of spontaneous circulation was longer in the ischemic ventricular fibrillation group (430 +/- 234 secs vs. 149 +/- 120 secs, p < .001). Restoration of spontaneous circulation rates were not different (electrical ventricular fibrillation 90% vs. ischemic ventricular fibrillation 65%). However, survival to 6 hrs was greater in the electrical ventricular fibrillation group (18 of 20, 90%) than in the ischemic ventricular fibrillation group (8 of 20, 40%, p = .002).</AbstractText>Resuscitation from ischemic ventricular fibrillation is more difficult than electrical ventricular fibrillation and is characterized by greater time to restoration of spontaneous circulation, frequent refibrillation, greater number of countershocks, higher epinephrine dose during resuscitation efforts, profound cardiac dysfunction, and a short-term survival rate approaching clinical experience. Ischemically induced ventricular fibrillation is a more clinically relevant model for the evaluation of resuscitation interventions.</AbstractText> |
8,771 | Prognostic role of post-infarction C-reactive protein in patients undergoing implantation of cardioverter-defibrillators: design of the C-reactive protein Assessment after Myocardial Infarction to GUide Implantation of DEfibrillator (CAMI GUIDE) study. | Patients at risk of sudden cardiac death (SCD) after myocardial infarction (MI) can currently be offered effective means of prevention, such as implantable cardioverter-defibrillators (ICD). However, predictors of SCD able to identify those patients who are at higher risk are still lacking. Whether C-reactive protein (CRP), a serum inflammatory marker with established prognostic accuracy after MI, can also be a predictor of SCD is unclear.</AbstractText>The CAMI GUIDE study is designed to evaluate the prognostic role of CRP in patients undergoing ICD implantation after MI according to MADIT II criteria (i.e. left ventricular ejection fraction<or=30%). CAMI GUIDE is a prospective observational study aimed at assessing the role of CRP in the risk-stratification of SCD after MI. CRP will be measured on the basis of a pre-specified cut-off value of 3 mg/l, before and 1 month after ICD implantation; clinical follow-up will last 24 months. The primary endpoint is the combined rate of SCD or fast ventricular tachycardia/ventricular fibrillation. Secondary endpoints will be total mortality, death due to acute coronary syndromes, death from pump failure, non-fatal MI, coronary revascularization, hospitalization for congestive heart failure or unstable angina and inappropriate ICD shocks. Twenty-four Italian centers will participate in enrollment of the 290 patients planned according to power analysis.</AbstractText>The CAMI GUIDE study will assess the predictive role of CRP in SCD in patients with previous MI undergoing ICD implantation. Its results will improve risk stratification, thereby enabling better-tailored and more cost-effective therapies to be undertaken in those patients whose need is greatest.</AbstractText> |
8,772 | An unusual case of tricuspid lesion in congenital corrected transposition of the great arteries. | An unusual case of severe supravalvular stenosing ring of the left atrium associated with tricuspid valve dysplasia in an adult symptomatic patient affected by congenitally corrected transposition and unrestrictive ventricular septal defect is reported. The stenosis of the systemic atrioventricular valve possibly prevented the development of obstructive pulmonary vascular disease; removal of the membrane, attached to the tricuspid annulus, together with pulmonary banding was carried out. Clinical conditions improved after surgery. The unusual stenotic lesion of the systemic right ventricular inflow allowed conservative surgical palliation in this adult patient. |
8,773 | Turbulence control with local pacing and its implication in cardiac defibrillation. | In this review article, we describe turbulence control in excitable systems by using a local periodic pacing method. The controllability conditions of turbulence suppression and the mechanisms underlying these conditions are analyzed. The local pacing method is applied to control Winfree turbulence (WT) and defect turbulence (DT) induced by spiral-wave breakup. It is shown that WT can always be suppressed by local pacing if the pacing amplitude and frequency are properly chosen. On the other hand, the pacing method can achieve suppression of DT induced by instabilities associated with the motions of spiral tips while failing to suppress DT induced by the instabilities of wave propagation far from tips. In the latter case, an auxiliary method of applying gradient field is suggested to improve the control effects. The implication of this local pacing method to realistic cardiac defibrillation is addressed. |
8,774 | Arrhythmogenesis in the heart: Multiscale modeling of the effects of defibrillation shocks and the role of electrophysiological heterogeneity. | The mechanisms of initiation of ventricular arrhythmias as well as those behind the complex spatiotemporal wave dynamics and its filament organization during ventricular fibrillation (VF) are the topic of intense research and debate. Mechanistic inquiry into the various mechanisms that lead to arrhythmia initiation and VF maintenance is hampered by the inability of current experimental techniques to resolve, with sufficient accuracy, electrical behavior confined to the depth of the ventricles. The objective of this article is to demonstrate that realistic 3D simulations of electrical activity in the heart are capable of bringing a new level of understanding of the mechanisms that underlie arrhythmia initiation and subsequent organization. The article does this by presenting the results of two multiscale simulation studies of ventricular electrical behavior. The first study aims to uncover the mechanisms responsible for rendering the ventricles vulnerable to electric shocks during a specific interval of time, the vulnerable window. The second study focuses on elucidating the role of electrophysiological heterogeneity, and specifically, differences in action potential duration in various ventricular structures, in VF organization. Both studies share common multiscale modeling approaches and analysis, including characterization of scroll-wave filament dynamics. |
8,775 | Negative filament tension in the Luo-Rudy model of cardiac tissue. | Scroll waves are vortices that occur in three-dimensional excitable media. Scroll waves have been observed in a variety of systems including cardiac tissue, where they are associated with cardiac arrhythmias. The disorganization of scroll waves into chaotic behavior is thought to be the mechanism of ventricular fibrillation, which lethality is widely known. One of the possible mechanisms of scroll wave instability is negative filament tension, which was studied theoretically using low-dimensional models of excitable medium. In this article we perform a numerical study of negative filament tension using the Luo-Rudy phase 1 model, which is widely used in cardiac electrophysiology. We show that this instability exists in this model, study its manifestation and discuss its relation to cardiac arrhythmogenesis. |
8,776 | Mechanical aortic and mitral valve replacement in infants and children. | The aim of this study was to evaluate early and late outcomes after mechanical systemic heart valve replacement in pediatric patients.</AbstractText>Between October 1981 and December 2003, 32 children (mean age 7.2 +/- 5.4 years; 4 months - 15.9 years) underwent mechanical mitral (MVR, n = 17), aortic (AVR, n = 13) or double valve replacement (DVR, n = 2) with St. Jude Medical valves. Twenty-two patients (69 %) had undergone previous cardiac surgery. Anticoagulation self-management was used since 1995.</AbstractText>The operative mortality was 3.1 %. Perioperative complications were complete heart block (n = 5), ventricular fibrillation (n = 1) and myocardial infarction (n = 1) and were exclusively related to patients with MVR. Mean calculated valve size ratio (geometric prosthesis orifice area/normal valve size area) was 1.72 (1.07 - 2.85) for AVR and 1.4 (0.88 - 3.12) for MVR. Mean follow-up was 9.1 +/- 6.6 years (range 0.4 - 23.2 years, cumulative 283 patient-years). There were two late deaths in patients with MVR. Actuarial survival after 10 years was 93.8 %. Late complications were endocarditis (n = 2), minor hemorrhagic event (n = 1), and stroke (n = 1). Anticoagulation self-management is well accepted by all patients/parents. Overall 10-year freedom from any anticoagulation-related adverse event with phenprocoumon was 89.1 % (1.2 %/patient year). Nine patients required reoperations: redo-MVR (outgrowth of prostheses (n = 3), pannus overgrowth (n = 2), closure of paravalvular leak after AVR (n = 2), partial aortic valve thrombosis (n = 1) and redo-DVR (n = 1 for endocarditis). Freedom from reoperation after 10 years was 80.9 %.</AbstractText>Mechanical valve prostheses are a valuable option for left-sided heart valve replacement in pediatric patients. Perioperative morbidity was exclusively related to patients with MVR. Oversizing was often possible to avoid early reoperation for outgrowth. The operative mortality and long-term morbidity are acceptable. Anticoagulation self-management is safe and well accepted.</AbstractText> |
8,777 | Clinical usefulness of electrophysiologic study (EPS)-guided risk stratification for life-threatening arrhythmia in patients with heart failure. | Ventricular tachyarrhythmia is one of the most important factors determining the prognosis of patients with heart failure and sudden death can be observed even during stable therapy controlling clinical heart failure. In this study, the usefulness of electrophysiologic study (EPS) for the prediction of a future arrhythmic event was evaluated in patients with heart failure.</AbstractText>The patient population consisted of 474 patients with a history of clinical heart failure but without an episode of spontaneous sustained ventricular tachycardia or fibrillation (VT/VF). A Holter ECG was performed in all patients, and 177 of the 474 patients underwent EPS because of a recording of nonsustained VT (NSVT, > 5 beats). When sustained VT/VF was inducible in EPS, the patient was assigned to implantation of a defibrillation device. The patients were divided into 3 groups, ie, 1) no NSVT (n = 297), 2) NSVT + no inducible VT/VF (n = 134), and 3) NSVT + inducible VT/VF (n = 43), and were followed-up for > 12 months. All patients were followed-up under standard therapy for heart failure. There were no significant differences in basic clinical characteristics and therapies among the 3 groups. During the follow-up period of 32 +/- 18 months, 56/474 patients suffered a VT/VF episode, ie, 21/297 in no NSVT, 14/134 in NSVT + no inducible VT/VF, and 21/43 in NSVT + inducible VT/VF patients (P = 0.032). All patients were rescued from sudden death among patients with an implanted defibrillator, but 11 patients without a defibrillator died.</AbstractText>In patients with heart failure, future arrhythmic events could be predicted by EPS and Holter ECG. EPS-guided risk stratification seems to be useful in managing patients with heart failure.</AbstractText> |
8,778 | A successfully novel ICD implantation and medical treatment in a child with LQT syndrome and self-limiting ventricular fibrillation. | Beta-blocker is the first line drug therapy for congenital long QT syndrome. However, in some children this drug is ineffective. In a non-responder patient, Shimizu et al. used Mexiletine to suppress the ventricular arrhythmias, obtaining a good result. In the high risk patient, the ICD is necessary. However the implantation of a device in small children can have technical problems. We report a case of a child affected by long QT syndrome with recurrent episodes of syncope due to self-limiting torsade de point/ventricular fibrillation, successfully treated by an association of mexiletin and propanolol, and in whom an ICD was implanted with a new subcutaneous approach. |
8,779 | Termination of atrial flutter by directed transesophageal atrial pacing during transesophageal echocardiography. | The purpose of this study was to evaluate termination of atrial flutter (AFL) by directed rapid transesophageal atrial pacing (TAP) with and without simultaneous transesophageal echocardiography (TEE) performed using a novel TEE tube electrode.</AbstractText><AbstractText Label="MATERIALS AND METHODS, AND RESULTS" NlmCategory="RESULTS">A total of 16 AFL patients (age 63+/-12 years; 13 males) with mean AFL cycle length of 224+/-24 ms (n=12) and mean ventricular cycle length of 448+/-47 ms (n=12) were analyzed using either an esophageal TO electrode (n=10) or a novel TEE tube electrode consisting of a tube with four hemispherical electrodes that is pulled over the echo probe (n=6). AFL could be terminated by directed rapid TAP using an esophageal TO electrode, leading to induction of atrial fibrillation (AF) (n=6), induction of AF and spontaneous conversion to sinus rhythm (SR) (n=3), and with conversion to SR (n=1). AFL could also be terminated by directed rapid TAP using the TEE tube electrode, with induction of AF (n=3) or induction of AF and spontaneous conversion to SR (n=3).</AbstractText>AFL can be terminated by directed rapid TAP with hemispherical electrodes with and without simultaneous TEE. TAP with the directed TEE tube electrode is a safe, simple, and useful method for terminating AFL.</AbstractText> |
8,780 | [The best of arrhythmia in 2006]. | Even though the year 2006 did not bring any major publication reporting therapeutic trials in the field of arrhythmia, it has been marked by the publication of important international guidelines on atrial fibrillation (AF), the treatment of ventricular arrhythmia and the prevention of sudden death, as well as studies on AF ablation, the external automatic defibrillator, the risk factors of ventricular fibrillation in the acute phase of myocardial infarction, and genetic aspects of the arrhythmogenic right ventricular dysplasia. |
8,781 | [The best of valvular heart disease in 2006]. | In the field of valvular diseases, the year 2006 has been above all marked by the publication of new joint AHA/ACC guidelines. Besides, other publications included severe aortic stenosis, drug therapy in chronic aortic regurgitation, the indications for surgery in asymptomatic mitral regurgitation, as well as valve surgery in the elderly and mismatch severity after aortic valve replacement. In a series of 66 cases of aortic stenosis with poor LV function undergoing stress echocardiography, it has been shown that whether the absence of contractile reserve identifies a high-risk subgroup for aortic valve replacement (33% vs. 6%), this exam does not predict the functional prognosis and the post-operative LV function improvement. Hence, the absence of contractile reserve should not contra-indicate aortic valve replacement surgery, even though the prognosis is severe, since the natural prognosis is extremely severe. The question of aortic valve replacement in case of mild stenosis with the indication of CABG remains difficult. Taking into account the important mortality of redo surgery, a study was in favor of a systematic aortic valve replacement associated to CABG in patients <75 years who had a mean aortic gradient > 30 mmHg, a LVH and aortic valve calcifications. Old patients (>80 years) with severe aortic stenosis have a very severe natural prognosis, authorizing wide indications for aortic valve replacement, in the absence of important comorbidities. The use of vasodilators in severe chronic aortic regurgitation remains debated. In a randomized study comparing Nifedipine 40 mg vs. Enalapril 20 mm vs. placebo, it has been shown that the use of a vasodilator does not modify the time of valvular surgery at all. After a mean follow-up of 7 years, the rates of aortic valve replacement were identical in the 3 groups, and there wa no difference regarding the preoperative regurgitation volume, LV dimensions and mass, and LVEF. The timing for huge chronic and asymptomatic mitral regurgitation remains debated, even though the present trend is to prefer early surgery, due to the risk of sudden death. A new study evidenced the interest of clinical and echocardiographic surveillance on a prospective series of 129 consecutive asymptomatic patients with severe degenerative mitral regurgitation. The surgical indication was only based on the occurrence of symptoms, an echographic LV diameters increase, a LV dysfunction, the presence of pulmonary hypertension or atrial fibrillation. At 8 years, the overall mortality was at 91 + 3%, with a survival rate not statistically different from the expected rates; 35 patients have been operated. The 6-years and 8-years surgical indication-free survival were respectively at 65 +/- 5% and 55 +/- 6%, with a null operative mortality, and favorable data regarding post-operative survival, symptoms and LV function. The indication for surgical correction of mitral regurgitation in the elderly remains a difficult problem, due to the surgical risk. The Mayo Clinic team analyzed the evolution of 284 patients > 75 years operated for mitral regurgitation between 1980 and 1995, compared to younger subjects (65 - 74 years old, n=504, and <65 years, n=556). The age-adjusted 5-years survival was lower in the older patients, but the age-adjusted observed/estimated survival ratios were similar in the different age groups. The perioperative risk, significantly higher in the older patients (p<0.001) decreased systematically for all age ranges in the most recent periods (the 1980-83 period vs. 1992-95), from 27% to 5%, 21% to 4%, and 7% to 2% respectively in patients > 75 years, 65-74 years and <65 years. An age >75 years was an independent predictive factor for the surgical mortality. These data show that, despite the surgical risk, the surgical treatment of mitral regurgitation should be extended to the oldest patients. One of the most surprising information provided in the ACC/AHA guidelines is the necessity of adding a daily dose of 75 to 100 mg of aspirin systematically to VKA in patients with mechanical prosthetic valves or in those with a valvular bioprosthesis with one or several risk factors for thrombo-embolic events (AF, history of thromboembolic event, LV dysfunction, hypercoagulable state). This major recommendation (Class 1, level of evidence B) appears surprising, since it is not actually based on definite results issued from randomized studies using these doses of aspirin. According to these guidelines, this association not only reduces the risk of thrombo-embolic events in patients with valvular prosthesis, but also decreases the mortality related to other cardiovascular causes (especially coronary artery disease), with the cost of a minimal risk augmentation for hemorrhagic complications. The importance of pejorative prognosis of mismatch (defined as an inadequacy between the aortic orifice size and patient's body surface after aortic valve replacement) has been subject to several publications this year. The substantial increase of post-operative events and poor survival in patients with this mismatch imply adapted preventive strategies in terms of selection of diameters and type of aortic valvular prosthesis and associated aortic surgical techniques (such as annular enlargement or supra-annular position). |
8,782 | [Comparative study of the electrophysiological properties of class iii medicinals (cardiocyclide, nibentan, sotalol) and evaluation of their efficacy in atrial fibrillation produced by auricular and vagal stimulation]. | The electrophysiological properties of cardiocyclide, nibentan and sotalol and their efficacy on a model of atrial fibrillation were compared in experiments in anaesthetized dogs. The electrophysiological parameters of drugs were investigated using the method of programmed electrical stimulation of myocardium on the background of excitation of the peripheral segment of the right vagus nerve with current pulses of increasing frequency. The atrial fibrillation was produced by short stimulation (10 pulses) of the right auriculum (10 Hz, 4 thresholds). Cardiocyclide was injected in a dose of 2.5-5.0 mg/kg; nibentan, 0.25 mg/kg; and sotalol, 2.5 mg/kg. Cardiocyclide was found to prevent vagotonic atrial fibrillation in 80% of cases; under vagal stimulation this drug maintained the electrophysiological attributes and exhibited the frequency-independent action inherent in this agent. Nibentan completely retained its ability to prolong the ventricular repolarization under vagal stimulation conditions, increased the effective atrial and ventricular refractory periods, and showed the ability to prevent and eliminate the vagotonic atrial fibrillation in 80-90% of cases. Under vagal stimulation, sotalol increased the repolarization and prolonged the effective refractory atrial and ventricular periods, reduced the heart rate, and suppressed the sinus node function. The action of sotalol was frequency-dependent. Sotalol was found to prevent the vagotonic atrial fibrillation in 60% of cases. |
8,783 | [Heart failure and cardiomyopathies: a case report]. | Isolated noncompaction of left ventricular myocardium is a rare congenital heart disease, characterized by an excessive prominence of trabecular meshwork, spaced out by deep intertrabecular recesses, consequent to the arrest of the normal myocardial embryogenesis. Although there are numerous descriptions, the pathophysiological effects of the structural alterations, like the clinical spectrum and the evolution of the disease, are not fully clarified. In this paper we evaluated the natural history of the disease, the family incidence and the alterations of the systolic and diastolic function. An interesting case report is described concerning a patient affected by noncompaction and atrial fibrillation. |
8,784 | Transient atrial fibrillation complicating acute inferior myocardial infarction: implications for future risk of ischemic stroke. | Atrial fibrillation (AF) that occurs as a frequent complication of myocardial infarction (MI) is associated with a poor clinical outcome. It nonetheless remains uncertain whether AF that occurs transiently during MI is associated with a subsequent increased risk of the development of AF and ischemic stroke.</AbstractText>We retrospectively studied the impact of transient AF on the long-term risk of the occurrence of AF, ischemic stroke, and mortality in 431 consecutive patients (mean [+/- SEM] age, 64 +/- 1 years; 75% men). All patients had experienced an acute inferior ST-segment-elevation MI and had preserved left ventricular ejection fraction (LVEF) [> 45%].</AbstractText>All patients were in sinus rhythm on hospital admission, and transient AF was observed in 59 patients (13.7%) during their hospitalization for MI. On hospital discharge, all patients were in sinus rhythm and had been prescribed antiplatelet agents alone as antithrombotic therapy. Patients in whom transient AF developed during MI were older (mean age, 70 +/- 1.4 vs 64 +/- 0.7 years, respectively; p < 0.01) and more likely to be women (37% vs 23%, respectively; p < 0.02) compared with those without AF. At 1-year follow-up, the incidence of AF (22.0% vs 1.3%, respectively; p < 0.01) and ischemic stroke (10.2% vs 1.8%, respectively; p < 0.01) was higher in patients with transient AF than in those without transient AF. The total mortality rate was nonetheless similar (5.6% vs 6.8%, respectively; p = 0.73); Cox regression analysis demonstrated that age > 65 years and transient AF during MI were independent predictors of the subsequent occurrence of AF and the development of ischemic stroke.</AbstractText>Transient AF complicating acute inferior MI is associated with an increased future risk of AF occurrence and ischemic stroke in patients with preserved LVEF, despite the use of antiplatelet therapy.</AbstractText> |
8,785 | Echocardiography-based spectrum of severe tricuspid regurgitation: the frequency of apparently idiopathic tricuspid regurgitation. | The cause of tricuspid valve (TV) regurgitation (TR) occasionally remains unclear. The objectives of our study were to define the causal spectrum of severe TR diagnosed by echocardiography at a tertiary medical center and to assess the relative frequency and determine the clinical and echocardiographic characteristics of TR without an apparent cause (idiopathic TR).</AbstractText>Consecutive patients with severe TR were identified by the echocardiography laboratory computerized database. The echocardiographic reports of all patients were reviewed and the causes of TR were determined. The echocardiographic studies and medical charts were reviewed in patients without an obvious cause of TR.</AbstractText>Of 242 consecutive patients diagnosed with severe TR, organic TV disease was evident in 23 patients (9.5%) and significant pulmonary hypertension (estimated pulmonary artery systolic pressure > 50 mm Hg) in an additional 157 patients (64.9%). After further excluding patients with various confounding factors, possibly associated with occult organic TV disease or significant pulmonary hypertension, 23 patients (9.5%) had severe TR without an apparent cause. Of these, TV coaptation appeared relatively intact, allowing adequate estimation of pulmonary artery pressure, in 15 patients (6.2% of all patients with severe TR; idiopathic TR group). Patients with idiopathic TR were older (76 +/- 10 years), with a high frequency of atrial fibrillation (93%), and prominent TV annular dilatation.</AbstractText>After excluding multiple potential causes of TR, severe TR is occasionally idiopathic. Annular dilatation (secondary to aging, atrial fibrillation, or other causes) is the likely mechanism of TR in these patients.</AbstractText> |
8,786 | Novel SCN5A mutation (Q55X) associated with age-dependent expression of Brugada syndrome presenting as neurally mediated syncope. | An association between Brugada syndrome and neurally mediated syncope has been described. Although mutations in SCN5A have been identified in Brugada syndrome, the genetic link between Brugada syndrome and neurally mediated syncope has not been determined.</AbstractText>The purpose of the study was to clinically and genetically characterize a man with recurrent syncope that originally was diagnosed as neurally mediated syncope at age 8 years but subsequently manifested as Brugada syndrome at age 17 years.</AbstractText>The proband underwent clinical examination, which included head-up tilt test, sodium channel provocation test, and electrophysiologic study. Genetic screening of SCN5A was performed for the proband and his family members. The biophysical properties of a mutant SCN5A channel in a heterologous expression system were studied using whole-cell, patch clamp technique.</AbstractText>The proband showed positive head-up tilt test, coved-type ST elevation recorded from the third intercostal space, and positive pilsicainide provocation test. Ventricular fibrillation was inducible at programmed electrical stimulation, consistent with characteristics of both Brugada syndrome and neurally mediated syncope. A novel nonsense SCN5A mutation (Q55X) was identified in the proband, his mother, and his asymptomatic brother. The heterologously expressed mutant channel was nonfunctional.</AbstractText>We genetically determined an SCN5A mutation in a patient showing the combined phenotype of neurally mediated syncope and Brugada syndrome. Neurally mediated syncope and Brugada syndrome may share, at least in part, a common pathophysiologic mechanism.</AbstractText> |
8,787 | Impact of heart failure and left ventricular function on long-term survival--report of a community-based cohort study in Taiwan. | There is little community-based information on heart failure (HF) prognosis in ethnic Chinese populations, in whom there is a low prevalence of coronary heart disease.</AbstractText>To study the impact of HF and left ventricular function on long-term all-cause mortality.</AbstractText>This community-based prospective cohort study included 2660 subjects (1215 men, 1445 women, mean age 54.4+/-11.9 years) over a 10 year follow-up period. The prevalence of HF was 5.5%. Hypertension was the most common factor related to HF. The five and ten year all-cause mortality was higher in the HF/preserved LVEF group (14.1% and 24.4%) and the HF/impaired LVEF group (29.2% and 48.2%) than in the HF-free group (6.0% and 14.6%, p<0.0001 for both). In multivariable Cox analyses, controlling for sex, LV mass, atrial fibrillation, hypertension, coronary heart disease, HF/preserved LVEF and HF/impaired LVEF were important predictors of all-cause mortality (p=0.007).</AbstractText>Hypertension is a major heart failure related disease. HF and LV systolic dysfunction are associated with a significant increase in all-cause mortality in an ethnic Chinese population.</AbstractText> |
8,788 | Isolated atrial segment pacing: an alternative to His bundle pacing after atrioventricular junctional ablation.<Pagination><StartPage>1443</StartPage><EndPage>1449</EndPage><MedlinePgn>1443-9</MedlinePgn></Pagination><Abstract><AbstractText Label="OBJECTIVES" NlmCategory="OBJECTIVE">This study was designed to investigate a practical alternative to His bundle pacing after atrioventricular (AV) junctional ablation by pacing a small area of isolated atrial tissue surrounding the AV node.</AbstractText><AbstractText Label="BACKGROUND" NlmCategory="BACKGROUND">His bundle pacing is preferred after AV junctional ablation in patients with refractory atrial fibrillation. However, it is technically difficult and not clinically useful at the present time.</AbstractText><AbstractText Label="METHODS" NlmCategory="METHODS">This study was conducted in an isolated working swine heart model (n = 5), with real-time imaging capabilities. A small area of atrial tissue surrounding the AV node and the His bundle was isolated using sequential radiofrequency ablation lesions.</AbstractText><AbstractText Label="RESULTS" NlmCategory="RESULTS">Complete AV block created by segmental atrial isolation was achieved in 5 of 5 experiments. The isolated atrial segment was bordered by the ablation lines, the tricuspid annulus, and the AV node-His bundle. The AV conduction was characterized using a pacing electrode implanted into the isolated atrial segment. Pacing from the atria, the ventricles, and the isolated atrial segment at different rates confirmed complete bidirectional block between the atria and isolated area, whereas antegrade and retrograde AV nodal conduction between the isolated atrial segment and the ventricles remained intact. Pacing from the isolated area produced minimal changes in systolic left ventricular pressure compared with baseline sinus rhythm (mean -2 mm Hg).</AbstractText><AbstractText Label="CONCLUSIONS" NlmCategory="CONCLUSIONS">Isolation of a small area of atrial tissue surrounding the AV node is feasible by transcatheter radiofrequency ablation. This procedure may be a useful alternative to conventional AV junctional ablation because it can create complete AV block, while in effect permitting the equivalent of His bundle pacing after AV junctional ablation.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Lü</LastName><ForeName>Fei</ForeName><Initials>F</Initials><AffiliationInfo><Affiliation>Cardiac Electrophysiology Laboratories, Department of Cardiovascular Disease, University of Minnesota, Minneapolis, Minnesota 55455, USA. luxxx074@umn.edu</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Iaizzo</LastName><ForeName>Paul A</ForeName><Initials>PA</Initials></Author><Author ValidYN="Y"><LastName>Benditt</LastName><ForeName>David G</ForeName><Initials>DG</Initials></Author><Author ValidYN="Y"><LastName>Mehra</LastName><ForeName>Rahul</ForeName><Initials>R</Initials></Author><Author ValidYN="Y"><LastName>Warman</LastName><ForeName>Eduardo N</ForeName><Initials>EN</Initials></Author><Author ValidYN="Y"><LastName>McHenry</LastName><ForeName>Brian T</ForeName><Initials>BT</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D016428">Journal Article</PublicationType><PublicationType UI="D013485">Research Support, Non-U.S. Gov't</PublicationType></PublicationTypeList><ArticleDate DateType="Electronic"><Year>2007</Year><Month>03</Month><Day>21</Day></ArticleDate></Article><MedlineJournalInfo><Country>United States</Country><MedlineTA>J Am Coll Cardiol</MedlineTA><NlmUniqueID>8301365</NlmUniqueID><ISSNLinking>0735-1097</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000818" MajorTopicYN="N">Animals</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D001283" MajorTopicYN="N">Atrioventricular Node</DescriptorName><QualifierName UI="Q000601" MajorTopicYN="Y">surgery</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002036" MajorTopicYN="N">Bundle of His</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D002304" MajorTopicYN="N">Cardiac Pacing, Artificial</DescriptorName><QualifierName UI="Q000379" MajorTopicYN="Y">methods</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D017115" MajorTopicYN="Y">Catheter Ablation</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D013552" MajorTopicYN="N">Swine</DescriptorName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="received"><Year>2006</Year><Month>7</Month><Day>24</Day></PubMedPubDate><PubMedPubDate PubStatus="revised"><Year>2006</Year><Month>11</Month><Day>29</Day></PubMedPubDate><PubMedPubDate PubStatus="accepted"><Year>2006</Year><Month>12</Month><Day>4</Day></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2007</Year><Month>4</Month><Day>3</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2007</Year><Month>5</Month><Day>26</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2007</Year><Month>4</Month><Day>3</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">17397673</ArticleId><ArticleId IdType="doi">10.1016/j.jacc.2006.12.034</ArticleId><ArticleId IdType="pii">S0735-1097(07)00129-5</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">17396562</PMID><DateCompleted><Year>2007</Year><Month>05</Month><Day>18</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>20</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0869-6047</ISSN><JournalIssue CitedMedium="Print"><Issue>2</Issue><PubDate><Year>2007</Year></PubDate></JournalIssue><Title>Vestnik Rossiiskoi akademii meditsinskikh nauk</Title><ISOAbbreviation>Vestn Ross Akad Med Nauk</ISOAbbreviation></Journal>[Mitochondrial ATP-dependent potassium channel. 2. The role of the channel in protection of the heart against ischemia]. | The cardioprotective properties of pharmacological and metabolic activators of mitoKATP are reviewed. Metabolic activators of the channels and data on their cardioprotective properties are discussed in the review. The authors adduce their own data concerning cardioprotective properties of mitoKATP channel metabolic activator (UDP). In experimental animals, UDP precursors, uridine and UMP, decrease myocardial ischemic alteration index and T-wave amplitude within 60 min after occlusion of the left coronary artery. Both effects are prevented by mitoKATP channel inhibitors, glibenclamide and 5-HD. UMP and uridine possess antiarrhythmic properties as well. These preparations decrease the number of premature ventricular beats, the duration of ventricular tachycardia and fibrillation, and these effects are eliminated mainly by glibenclamide. Thus, mitoKATP plays a significant role in prevention of both ischemic lesions and rhythm disorders. The prospects of application of metabolic activators to prevent and treat myocardial infarction are discussed. |
8,789 | Pre-procedural predictors of atrial fibrillation recurrence after circumferential pulmonary vein ablation. | The success rate of circumferential pulmonary vein ablation (CPVA) to treat atrial fibrillation (AF) ranges from 60 to 90%, depending on the series. The objective of the study was to identify predictors of AF recurrence after a standardized CPVA procedure.</AbstractText>A series of 148 consecutive patients undergoing CPVA for symptomatic paroxysmal (60.8%), persistent (23.6%), or permanent (15.5%) AF refractory to antiarrhythmic drugs were included in the study. CPVA with the creation of supplementary block lines along the posterior wall and mitral isthmus was performed and a minimum of 6 months follow-up completed in all patients. Structural heart disease was present in 19.6% and hypertension in 33.8% of patients. After 13.1 +/- 8.4 months follow-up, 73.6% of patients were free of AF recurrences after a mean of 1.18 +/- 0.45 procedures/patient (one procedure in 85.2%, two procedures in 14.8%, and three procedures in 2.7%). Univariable analysis showed that the risk of AF recurrence increases with age (HR 1.03; 95% CI 1.00-1.06, P = 0.031), with the presence of previous hypertension (HR 2.7; 95% CI 1.43-5.07, P = 0.002), and if AF is permanent (HR 2.23; 95% CI 1.08-4.59, P = 0.042). In addition, larger anteroposterior left atrial diameter (LAD) (HR 1.11; 95% CI 1.05-1.18, P = 0.001) and larger left ventricular end-systolic diameter (HR 1.07; 95% CI 1.00-1.15, P = 0.029) prior to the procedure were associated with AF recurrence after CPVA. Cox regression analysis showed that hypertension (OR = 2.8; 95% CI 1.5-5.4; P = 0.002) and LAD (OR = 1.1; 95% CI 1.05-1.19, P < 0.001) were independent predictors of AF recurrence. The mean predicted proportion of patients with AF recurrence after CPVA of the multivariable model showed a linear relationship with the increase in LAD prior to the procedure. The presence of hypertension further increased the mean predicted proportion of patients with AF recurrence at each LAD.</AbstractText>Hypertension and LAD are independent pre-procedural predictors of AF recurrence after CPVA to treat AF. These data may help in patient selection for AF ablation.</AbstractText> |
8,790 | On the role of ventricular conduction time in rate stabilization for atrial fibrillation. | Ventricular pacing (VP) could stabilize the ventricular rhythm in atrial fibrillation (AF). This study investigates the role of ventricular conduction time (VCT) in rate stabilization for AF.</AbstractText>A novel computer model was used to generate various patterns of RR intervals in AF. For each model configuration, the rate stabilization effect of VP was compared with respect to different VCTs. In all tested cases, the ventricular rate in AF could be stabilized at pacing intervals longer than the shortest spontaneous RR intervals. For each model configuration, slightly longer pacing interval (difference <100 ms) was needed to achieve 95% VP when the antegrade/retrograde VCT was increased from 10/10 to 110/110 ms, whereas the VCT had less effect at lower pacing rate. Although longer VCT was associated with increased percentage of ventricular fusion, its role was diminished at higher pacing rate when more retrograde waves could conduct to the atrium.</AbstractText>Ventricular conduction time has limited effects on rate stabilization, which could be explained by multi-level interactions between antegrade waves induced by AF and retrograde waves induced by VP.</AbstractText> |
8,791 | A case of recurrent transient left ventricular apical ballooning associated with atrial fibrillation. | We report the case of a post-menopausal female who presented two episodes of transient left ventricular apical ballooning associated with rapid atrial fibrillation within a four-month period. The clinical features of this phenomenon also known as Tako-tsubo mimic acute myocardial infarction and may be a form of catecholamine-induced neurogenic stunning. The case illustrates that typical ECG features could be masked by atrial fibrillation with rapid ventricular response. |
8,792 | Arrhythmic complications of electrical cardioversion: relationship to shock energy. | Existing guidelines for electrical cardioversion (ECV) of atrial arrhythmias suggest starting at a low energy setting on the grounds that shocks of high energy might damage the myocardium or trigger more serious arrhythmias. We hypothesised that more powerful shocks would exceed the upper limit of vulnerability for inducing ventricular fibrillation. The initial use of higher energy could therefore reduce arrhythmic complications.</AbstractText>We collected data on the sequence of shocks delivered and the resulting changes in cardiac rhythm in 1896 patients who underwent transthoracic ECV. Rhythm strips derived from 200 consecutive ECV attempts were studied to verify the accuracy of the synchronisation of the shocks delivered.</AbstractText>In 2522 attempts at transthoracic ECV, 6398 shocks were delivered, 1243 in atrial flutter or atrial tachycardia, the others in AF. Ventricular fibrillation was significantly more common after shocks of < 200 J (5 of 2959 vs. 0 of 3439 shocks, p<0.05, Fischer's exact test). Conversion of atrial flutter or atrial tachycardia to AF was also more common at < 200 J (20 of 930 shocks vs. 1 of 313 shocks at > or = 200 J, p<0.05, chi2 test). Sinus bradycardia or sinus arrest complicated 0.95% of cardioversion attempts, but none required emergency pacing. The incidence of bradycardia was not related to the energy used.</AbstractText>Shocks of > 200 J are associated with fewer tachyarrhythmic complications, and do not increase the risk of other serious complications. Bradycardia after cardioversion is very rarely of clinical importance.</AbstractText> |
8,793 | Inappropriate shock delivery by implantable cardioverter defibrillator due to electrical interference with washing machine. | We report a patient with hypertrophic cardiomyopathy who received an inappropriate implantable cardioverter defibrillator shock due to electrical interference from a washing machine. This electrical interference was detected as an episode of ventricular fibrillation with delivery of shock without warning symptoms. |
8,794 | Racial disparity and technology diffusion: the case of cardioverter defibrillator implants, 1996-2001. | Although implantable cardioverter defibrillator (ICD) therapy is widely endorsed for preventing sudden cardiac death (SCD), prior research documented a large black-white disparity in ICD therapy among the elderly. No studies have examined this disparity among nonelderly adults or over time as ICD therapy became widely diffused.</AbstractText>This study compares disparity in use of ICD therapy for 1996-1998 to 1999-2001 between African Americans and other adults.</AbstractText>The National Hospital Discharge Survey is used to compare ICD utilization between black and other adults diagnosed with ventricular tachycardia, ventricular fibrillation or cardiac arrest.</AbstractText>Adjusting for patient and hospital characteristics, ICD use per 100 at-risk patients rose from 11.0 to 27.3 among African Americans and from 24.0 to 37.5 among other adults between 1996-1998 and 1999-2001. Although the disparity was evident throughout the study period, it declined by 40%. Compared with their nonblack counterparts, black adults at risk for SCD were five years younger on average (p < 0.01) and more likely to be female (p < 0.01).</AbstractText>As ICD therapy became more widely available, use of this technology increased faster for black versus other adults, and the disparity in use declined but was not eliminated. Policymakers and clinicians should focus on increasing access among underserved populations to promising new technologies. Research focusing only on the elderly may miss important racial disparities when there is a race difference in the age distribution of disease risk. Further research should explore the relationship of technology diffusion to disparities in health service use.</AbstractText> |
8,795 | [Is potential equalization in hemodialysis treatments necessary?]. | In some cases in haemodialysis blood access is established with a special type of central venous catheter (CVC), sometimes called a central dialysis catheter (CDC), instead of an AV fistula or graft. This central venous catheter tip is placed very close to the heart, increasing the probability of a leakage of electrical current passing through the heart. This may cause arrhythmia or ventricular fibrillation. This current is generally referred to as patient leakage current and has to be kept very low for patient safety. All staff involved in CVC treatments, nursing staff as well as technicians, should be aware of this particular risk to the patient. The purpose of this article is to discuss the background of the above-mentioned safety issue and suggest precautionary measures for minimising this risk. Precautions discussed include potential equalisation, use of separating transformers, periodic maintenance (normally performed by a service technician) and physical placement of the equipment used in the vicinity of the patient (normally the responsibility of the nursing staff). |
8,796 | The TCM stage-oriented treatment for chronic cardiac insufficiency. | Generally, heart failure at the stable stage can be treated mainly with TCM drugs. Cardiac insufficiency of degree I and II can be simply treated with Chinese drugs. However, the western medicine ACEI is suggested to be used at the same time. For heart failure of degree III, measures of the western medical treatment should be adopted accordingly, such as the use of diuretics or Digoxin to control atrial fibrillation; beta-receptor blockers to increase the density of beta-receptor on the depleted myocardial cell membrane, so as to increase the sensitivity of the myocardial cells to CA, and effectively prevent the fatal ventricular fibrillation. At the acute aggravation stage of cardiac insufficiency, the inducing factors should be first eliminated to control the condition as soon as possible; and at the critical moment, modern medicine should be used. In case of acute pulmonary edema, emergency treatment should be given to save the patient's life. When the acute pulmonary edema is alleviated, Chinese drugs can be used, based on the TCM syndrome differentiation, mainly for removing the pathogenic fluid retention, and restoring the heart-qi and heart-yang. |
8,797 | Sudden death in a patient with multiple left anterior descending coronary artery fistulas to the left ventricle. | Coronary fistulas to cardiac chambers are an infrequent anomaly and usually are found casually. Although the majority of patients are asymptomatic, in rare cases it may cause coronary steal and cardiac ischemia. We present a patient with a left anterior descending coronary artery with multiple small fistulas to the left ventricle that suffered angina and an episode of ventricular fibrillation that required electrical cardioversion and an intracardiac defibrillator. |
8,798 | Comparative antiarrhythmic efficacy of amiodarone and dronedarone during acute myocardial infarction in rats. | The effects of dronedarone, a non-iodinated derivative of amiodarone, on ventricular tachycardia and ventricular fibrillation post-myocardial infarction are not well established. Fifty-five Wistar rats were randomly allocated to a 2-week oral treatment with either vehicle (n=18), amiodarone (30 mg/kg, n=20), or dronedarone (30 mg/kg, n=17). After acute coronary artery ligation, a single-lead electrocardiogram was continuously recorded for 24 h and episodes of ventricular tachycardia/fibrillation as well as mortality rates were analysed. Monophasic action potential recordings were obtained from the left ventricular epicardium at baseline and 24 h post-myocardial infarction. Thyroid hormones and catecholamines were measured using radioimmunoassay. Thyroid function was similar in the 3 groups. Compared to controls, amiodarone and dronedarone equally decreased the number of ventricular tachycardia/fibrillation episodes by approximately 75%. Both agents prevented the increase in monophasic action potential duration and in beat-to-beat variation. Norepinephrine levels were lower only after amiodarone treatment. Despite the observed antiarrhythmic effect, total mortality did not differ between groups (38.8% in controls, 30.0% in the amiodarone group and 58.8% in the dronedarone group), because of excess bradyarrhythmic mortality in both drug groups that reached significance in the dronedarone group. Dronedarone and amiodarone display similar antiarrhythmic efficacy post-myocardial infarction, partly by preventing repolarization inhomogeneity. However, dronedarone increases bradyarrhythmic mortality possibly secondary to its negative inotropic effects. |
8,799 | Post-shock synchronized pacing in isolated rabbit left ventricle: evaluation of a novel defibrillation strategy. | A failed near-threshold defibrillation shock is followed by an isoelectric window (IEW) and rapid repetitive responses that reinitiate ventricular fibrillation (VF). We hypothesized that properly timed (synchronized) postshock pacing stimuli (SyncP) may capture the recovered tissues during the repetitive responses and prevent postshock reinitiation of VF, resulting in improved defibrillation efficacy.</AbstractText>We explored the effect of postshock SyncP on defibrillation efficacy in isolated rabbit hearts (n = 12). Optical recording-guided real-time detection and electrical stimulation (5 mA) of recovered tissues in anterior/posterior left ventricle (LV) were performed following IEW. The IEW duration was found to be 69 +/- 13 ms. With the same shock strength, successful and failed defibrillation episodes were associated with 50% and 15% of the myocardium, respectively, captured by the SyncP (P < 0.001). Electrical stimulation from the posterior LV resulted in 75% of episodes capturing myocardium, as compared with anterior LV stimulation (55%; P < 0.01) and higher successful defibrillation rate (14%, posterior vs. 3%, anterior LV). The overall success in terminating VF by postshock SyncP was approximately 10%. The causes for failed myocardium capture by postshock SyncP included lack of IEW after low-strength shock (42.9%), incorrect locations of reference site (25.7%) and pacing electrodes (17.9%), and others, such as wave breakthroughs (13.5%).</AbstractText>Postshock SyncP was feasible and the larger the myocardium captured area, the more likely was the successful defibrillation. Postshock SyncP delivered to the posterior LV was more effective than anterior LV to terminate VF.</AbstractText> |
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