Unnamed: 0 int64 0 2.34M | titles stringlengths 5 21.5M | abst stringlengths 1 21.5M |
|---|---|---|
8,400 | High plasma levels of tissue inhibitor of metalloproteinase-1 (TIMP-1) and interleukin-8 (IL-8) characterize patients prone to ventricular fibrillation complicating myocardial infarction. | Atherosclerotic plaques prone to cause thrombotic complications and plaque rupture account for the majority of fatal myocardial infarctions (MI), which may be complicated by ventricular fibrillation (VF). Matrix-degrading metalloproteinases (MMPs) and their inhibitors (TIMPs) are expressed in atherosclerotic lesions and contribute to plaque vulnerability. Interleukin-8 (IL-8) is one of the predominant chemokines interacting with MMPs and TIMPs and the coagulation system. The aim of the present study was to assess potential differences of levels of MMP-9, TIMP-1 and IL-8 in postmyocardial infarction patients with or without VF complicating acute MI.</AbstractText>Blood samples were taken from 45 patients with VF complicating acute MI and from 88 patients without VF. All samples were collected during a symptom-free interval remote from the acute ischemic event with a median of 556 days. The markers of interest were TIMP-1, MMP-9 and IL-8.</AbstractText>IL-8 and TIMP-1 levels were significantly higher among patients with VF than among patients without VF (p<0.001). In a logistic regression approach IL-8 was an independent indicator of patients prone to VF during MI (p=0.03). High levels of TIMP-1 (p=0.05), MMP-9 (p=0.03), the MMP-9/TIMP-1 ratio (p=0.049) and hypertension (p=0.02) were found to be indicators in patients with reinfarction or unstable angina pectoris during follow-up. Hypertension (p=0.02) and MMP-9 (p=0.03) were the only significant indicators characterizing patients undergoing coronary reinterventions, such as percutaneous coronary interventions and coronary bypass surgery.</AbstractText>Higher TIMP-1 and IL-8 levels are present in patients with VF complicating MI. High TIMP-levels may be related to the degree of fibrosis which is a substrate for electrical instability and may contribute to the occurrence of VF. Patients prone to develop VF during MI seem to have an increased proinflammatory condition compared to patients without VF.</AbstractText> |
8,401 | Cardiac memory induced by QRS widening due to propafenone toxicity. | Propafenone toxicity can cause significant QRS widening and markedly abnormal ventricular activation pattern. Aberrant ventricular activation upon its resolution is known to produce persistent T-wave changes known as "cardiac memory" (CM). A 74-year-old woman presented with a severely abnormal electrocardiogram consistent with propafenone toxicity. As her QRS complex narrowed, T-wave inversions developed with the T-wave axis and resolution kinetics consistent with CM. Abnormal ventricular activation due to propafenone toxicity can result in CM development. |
8,402 | Shocking truths about implantable cardioverter defibrillator monitoring zones. | A 36 year-old man with hypertrophic cardiomyopathy and an ATLAS + DR implantable cardioverter defibrillator (ICD) (St. Jude Medical, Inc., St. Paul, MN, USA) for primary prevention received a shock while cycling. The ventricular fibrillation detection threshold was 182 beats/min. An additional monitoring zone was programmed to 156 beats/min with all discriminators "on" except morphology. On interrogation, the ICD shock followed sinus tachycardia. In the absence of a monitoring zone, device therapy would not have been expected. We explore the mechanisms by which monitoring zones could potentially contribute to inappropriate ICD therapy and offer trouble-shooting tips. |
8,403 | An approach to ablate and pace:AV junction ablation and pacemaker implantation performed concurrently from the same venous access site. | Atrioventricular junction (AVJ) ablation combined with permanent pacemaker implantation (the "ablate and pace" approach) remains an acceptable alternative treatment strategy for symptomatic, drug-refractory atrial fibrillation (AF) with rapid ventricular response. This case series describes the feasibility and safety of catheter ablation of the AVJ via a superior vena caval approach performed during concurrent dual-chamber pacemaker implantation.</AbstractText>A total of 17 consecutive patients with symptomatic, drug-refractory, paroxysmal AF underwent combined AVJ ablation and dual-chamber pacemaker implantation procedure using a left axillary venous approach. Two separate introducer sheaths were placed into the axillary vein. The first sheath was used for implantation of the pacemaker ventricular lead, which was then connected to the pulse generator. Subsequently, a standard ablation catheter was introduced through the second axillary venous sheath and used for radiofrequency (RF) ablation of the AVJ. After successful ablation, the catheter was withdrawn and the pacemaker atrial lead was advanced through that same sheath and implanted in the right atrium.</AbstractText>Catheter ablation of the AVJ was successfully achieved in all patients. The median number of RF applications required to achieve complete AV block was three (range 1-10). In one patient, AV conduction recovered within the first hour after completion of the procedure, and AVJ ablation was then performed using the conventional femoral venous approach. There were no procedural complications.</AbstractText>Catheter ablation of the AVJ can be performed successfully and safely via a superior vena caval approach in patients undergoing concurrent dual-chamber pacemaker implantation.</AbstractText> |
8,404 | Biventricular upgrading in patients with conventional pacing system and congestive heart failure: results and response predictors. | There are few studies on cardiac resynchronization therapy (CRT) in heart failure (HF) patients with preexisting right ventricular (RV) pacing. The purpose of this study was to determine the efficacy of CRT upgrading in RV-paced patients and the predictivity of electromechanical dyssynchrony parameters (EDP) evaluated by standard echocardiography (ECHO) and tissue Doppler imaging (TDI).</AbstractText>Thirty-eight consecutive patients with HF [New York Heart Association (NYHA) class III or IV, LVEF < 35%], prior continuous RV pacing, and absence of atrial fibrillation were enrolled in the presence of a paced QRS > or = 150 ms and evaluated by ECHO and TDI. A responder was defined as a patient with a favorable change in NYHA class and neither HF hospitalization nor death, plus an absolute increase of LVEF > or = 10 units.</AbstractText>At six-months follow-up, the whole study population had significant improvement in symptoms, systolic function, and QRS duration (P < 0.001); 32 (84%) patients had a favorable clinical outcome, 25 (66%) were considered responders according to the previous definition. Postimplant QRS was similarly reduced in both responders and nonresponders, whereas EDP had a significant improvement only in responders (P < 0.05). Using EDP, 23 (79%) patients were responders compared with 2 (22%) patients without mechanical dyssynchrony (P = 0.002).</AbstractText>In HF patients with previous RV pacing, CRT is effective to improve clinical, functional outcome, and LV performance and to reduce electromechanical dyssynchrony in a large proportion of patients. Dyssynchrony evaluated by standard and TDI ECHO can be useful for CRT selection of paced patients.</AbstractText> |
8,405 | Sustained polymorphic arrhythmias induced by programmed ventricular stimulation have prognostic value in patients receiving defibrillators. | Patients with ischemic cardiomyopathy (ICM) who have monomorphic ventricular tachycardia (VT) induced by programmed ventricular stimulation (PVS) are at increased risk of sudden cardiac death (SCD). Among a primary prevention population, the prognostic significance of induced polymorphic ventricular arrhythmias is unknown.</AbstractText>A total of 105 consecutive patients who received an implantable cardioverter-defibrillator (ICD) for primary prevention of SCD in the setting of ICM and non-sustained VT were retrospectively evaluated. Seventy-five patients (group I) had induction of monomorphic VT and 30 patients (group II) had a sustained ventricular arrhythmia other than monomorphic VT (ventricular flutter, ventricular fibrillation, and polymorphic VT) induced during PVS.</AbstractText>Baseline characteristics were similar between group I and group II except for ejection fraction (25% vs. 31%, P = 0.0001) and QRS duration (123 milliseconds vs. 109 milliseconds, P = 0.04). Sixteen of 75 (21.3%) patients in group I and 6 of 30 (20%) patients in group II received appropriate ICD therapy (P = 0.88). Survival free from ICD therapy was similar between groups (P = 0.54). There was a trend toward increased all-cause mortality among patients in group I by Kaplan-Meier analysis (P = 0.08). However, when adjusted for age, EF, and QRS duration mortality was similar (P = 0.45).</AbstractText>There is no difference in rates of appropriate ICD discharge or mortality between patients dichotomized by type of rhythm induced during PVS. These results suggest that patients in this population who have inducible VF or sustained polymorphic VT have similar rates of subsequent clinical ventricular tachyarrhythmias as those with inducible monomorphic VT.</AbstractText> |
8,406 | [The application of 4-aminopyridine in calcium channel inhibitors acute poisoning]. | Calcium channel inhibitors have been extensively used to treat arterial hypertension, ischaemic heart disease and supraventricular rhythm irregularities. The poisonings by that category of drugs are extremely dangerous, particularly when accompanied by intoxication with other drugs affecting the circulatory function. This paper reports 3 cases of poisonings with calcium channel inhibitors (verapamil and diltiazem) in combination with angiotensin convertase inhibitors and nonselective beta-adrenolytics. Circulatory insufficiency and cardiac rhythm abnormalities were noted in all reported cases, in one in the form of ventricular bigeminy and two episodes of ventricular fibrillation, while in the two other cases in the form of 1 degree atrioventricular block. The persisting hypotonia combined with heart rhythm disturbances could not be prevented by the typical conservative treatment involving intravenous administration of infusion fluids, calcium formulations, catecholamines and atropin. The application of 4-amino-pyridine (Pymadin) caused that arterial tension and heart rate were higher, and the heart rhythm disturbances disappeared. The reported cases suggest a beneficial effect of 4-aminopyridine used to treat cases of poisonings by calcium channel inhibitors; however, up to the present time, no detailed procedures have been determined for 4-aminopyridine administration in cases like those reported above. 4-aminopyridine has not been included in the list of the antidotes approved by the WHO and, therefore, broader tests and more clinical observations are required to confirm its therapeutic value. |
8,407 | Can the direct cardiac effects of the electric pulses generated by the TASER X26 cause immediate or delayed sudden cardiac arrest in normal adults? | There is only a small amount of experimental data about whether the TASER X26, a nonlethal weapon that delivers a series of brief electrical pulses to cause involuntary muscular contraction to temporarily incapacitate an individual, can initiate ventricular fibrillation to cause sudden cardiac arrest either immediately or sometime after its use. Therefore, this paper uses the fundamental law of electrostimulation and experimental data from the literature to estimate the likelihood of such events. Because of the short duration of the TASER pulses, the large duration of the cardiac cell membrane time constant, the small fraction of current from electrodes on the body surface that passes through the heart, and the resultant high pacing threshold from the body surface, the fundamental law of electrostimulation predicts that the TASER pulses will not stimulate an ectopic beat in the large majority of normal adults. Since the immediate initiation of ventricular fibrillation in a normal heart requires a very premature stimulated ectopic beat and the threshold for such premature beats is higher than less premature beats, it is unlikely that TASER pulses can immediately initiate ventricular fibrillation in such individuals through the direct effect of the electric field generated through the heart by the TASER. In the absence of preexisting heart disease, the delayed development of ventricular fibrillation requires the electrical stimuli to cause electroporation or myocardial necrosis. However, the electrical thresholds for electroporation and necrosis are many times higher than that required to stimulate an ectopic beat. Therefore, it is highly unlikely that the TASER X26 can cause ventricular fibrillation minutes to hours after its use through direct cardiac effects of the electric field generated by the TASER. |
8,408 | Electrocardiographic and electrophysiologic characteristics in patients with Brugada type electrocardiogram and inducible ventricular fibrillation: single center experience. | The study examined the electrocardiographic and electrophysiologic characteristics in relation to programmed ventricular stimulation (PVS)-induced ventricular fibrillation (VF) in patients with Brugada syndrome.</AbstractText>Thirty-four patients with a Brugada-type electrocardiogram (ECG) were enrolled. Twelve patients had a type 1 ECG, 12 had a type 2 ECG, and 10 had a type 3 ECG. PVS was performed with up to 2 ventricular premature beats from the right ventricular apex and outflow tract at 2 basic cycle lengths (600 and 400 ms). VF was induced in 17 of 23 (74%) asymptomatic patients and 10 of 11 (91%) symptomatic patients (p<0.05). The 27 patients in whom VF was induced by PVS and 7 patients without inducible VF were followed up for 47.1+/-33.7 months. One sudden death occurred during the follow-up period among asymptomatic patients with inducible VF, and no sudden death occurred among patients without inducible VF.</AbstractText>In conclusion, inducibility of ventricular arrhythmia is high in patients with Brugada syndrome, but it does not correlate with clinical presentation. Few arrhythmic events occur during follow up. However, the present study data suggest that electrophysiologic study-induced VF does not predict arrhythmic events during follow up.</AbstractText> |
8,409 | Predictors of congestive heart failure in patients on maintenance hemodialysis. | Cardiovascular disease is a major cause of death in patients on maintenance hemodialysis (HD). Predictors of congestive heart failure (CHF) events in patients on HD were investigated, focusing on left ventricular (LV) function.</AbstractText>One hundred consecutive patients on HD were followed for at least 5 years after index examination performed 1 day after the last HD session. Tests included M-mode and Doppler echocardiography and plasma brain natriuretic peptide (BNP) and hemoglobin (Hb) concentration measurements. Patients with atrial fibrillation or poor echocardiographic images were excluded. Confounding factors included diabetes mellitus (DM), hypertension, age, HD duration, LV fractional shortening, E/A of transmitral flow velocity pattern, Tei index, LV mass index (LVMI), BNP level, Hb, and use of antihypertensive or antiarrhythmic drugs. Six CHF events occurred during 1,703+/-565 days. DM and Hb <10 g/dl were identified as independent predictors of CHF events in a stepwise Cox regression model after DM, LVMI, BNP, and Hb <10 g/dl were selected in the univariate analysis. The hazard ratio (confidence interval) was 10.96 (1.49-80.44) for DM, and 23.00 (2.41-219.76) for Hb <10 g/dl. The estimated hazard across time was constant (T_COV*DM; p=0.726, T_COV*Hb <10 g/dl; p=0.681) by time-dependent covariates analysis.</AbstractText>In patients on maintenance HD, DM and anemia (Hb <10 g/dl), but not echo-derived cardiac function, predicted CHF events.</AbstractText> |
8,410 | Exercise training normalizes beta-adrenoceptor expression in dogs susceptible to ventricular fibrillation. | Previous studies demonstrated an enhanced beta(2)-adrenoceptor (AR) responsiveness in animals susceptible to ventricular fibrillation (VF) that was eliminated by exercise training. The present study investigated the effects of endurance exercise training on beta(1)-AR and beta(2)-AR expression in dogs susceptible to VF. Myocardial ischemia was induced by a 2-min occlusion of the left circumflex artery during the last minute of exercise in dogs with healed infarctions: 20 had VF [susceptible (S)] and 13 did not [resistant (R)]. These dogs were randomly assigned to either 10-wk exercise training [treadmill running; n = 9 (S) or 8 (R)] or an equivalent sedentary period [n = 11 (S) or 5 (R)]. Left ventricular tissue beta-AR protein and mRNA were quantified by Western blot analysis and RT-PCR, respectively. Because beta(2)-ARs are located in caveolae, caveolin-3 was also quantified. beta(1)-AR gene expression decreased ( approximately 5-fold), beta(2)-AR gene expression was not changed, and the ratio of beta(2)-AR to beta(1)-AR gene expression was significantly increased in susceptible compared with resistant dogs. beta(1)-AR protein decreased ( approximately 50%) and beta(2)-AR protein increased (400%) in noncaveolar fractions of the cell membrane in susceptible dogs. Exercise training returned beta(1)-AR gene expression to levels seen in resistant animals but did not alter beta(2)-AR protein levels in susceptible dogs. These data suggest that beta(1)-AR gene expression was decreased in susceptible dogs compared with resistant dogs and, further, that exercise training improves beta(1)-AR gene expression, thereby restoring a more normal beta-AR balance. |
8,411 | Autologous right atrial wall patch for closure of atrial septal defects. | We used the right atrial free wall as a patch to close atrial septal defects (ASD) and report its results.</AbstractText>Between July 1998 and April 2006, 87 patients (mean age, 21.9 +/- 13.9 years; range, 7 months to 54 years), underwent closure of ASD with an autologous right atrial free wall patch. The underlying diagnosis were very large secundum ASD in 51 patients, sinus venosus defect in 15, primum ASD in 5, large defect resulting from excision of a left atrial myxoma in 12, complete atrioventricular canal defect in 1, total anomalous pulmonary venous return with ASD in 2, and Ebstein anomaly with a large ASD in 1. Associated surgical procedures were mitral valve repair in 18 patients, repair of total or partial anomalous pulmonary venous drainage in 17, mitral valve replacement in 1, and tricuspid valve repair for Ebstein anomaly in 1.</AbstractText>There were two early deaths. One patient with primum defect and preoperative congestive heart failure died 3 weeks postoperatively from refractory ventricular fibrillation. Another patient died from persistent congestive heart failure after undergoing reoperation for residual mitral regurgitation. The remaining patients were discharged after 4 to 9 days. No flow was detected across the septal patch on predischarge echocardiography. At a mean follow up of 53.4 +/- 26.7 months (range, 1 to 103 months), all patients except 1 are in sinus rhythm. One patient underwent reoperation for failed mitral valve repair after 1 month. At reoperation, the patch was intact with normal texture and without any suture dehiscence. Histopathologic examination of the explanted patch revealed viable endothelium and subendothelial muscle on both the surfaces of the patch. Results of Holter monitoring in 9 patients were normal. Electrophysiologic studies in 2 patients recorded normal atrial potentials from the site of the patch. No patch shrinkage, calcification, or thromboembolic complications were noted.</AbstractText>The autologous, free, right atrial wall can be safely used as a patch for ASD closure and offers several advantages.</AbstractText> |
8,412 | Atrial cardiomyocyte tachycardia alters cardiac fibroblast function: a novel consideration in atrial remodeling. | Atrial fibrillation (AF) causes tachycardia-induced atrial electrical remodeling, contributing to the progressive nature of the arrhythmia. Ventricular dysfunction due to a rapid response to AF can cause structural remodeling, but whether AF itself directly promotes atrial fibrosis is controversial. This study investigated the hypothesis that rapid atrial cardiomyocyte activation produces factors that influence atrial fibroblast proliferation and secretory functions.</AbstractText>Cultured canine atrial fibroblasts were treated with medium from rapidly-paced atrial cardiomyocytes, non-paced cardiomyocytes and cardiomyocyte-pacing medium only, and analyzed by [(3)H]thymidine incorporation, Western blot and real-time RT-PCR.</AbstractText>Rapidly-paced cardiomyocyte-conditioned medium reduced [(3)H]thymidine uptake compared to non-paced cardiomyocyte-conditioned medium and medium alone (approximately 85%, P<0.01). Rapidly-paced cardiomyocyte medium increased alpha SMA protein (approximately 55%, p<0.001), collagen-1 (approximately 85%, P<0.05) and fibronectin-1 (approximately 205%, P<0.05) mRNA expression vs. controls. The angiotensin-1 receptor blocker valsartan attenuated pacing-induced alpha SMA changes but did not affect fibroblast proliferation. Suppression of contraction with blebbistatin did not prevent tachypacing-induced changes in [(3)H]thymidine uptake or alpha SMA upregulation, pointing to a primary role of electrical over mechanical cardiomyocyte activity. Atrial tissue from 1-week atrial-tachypaced dogs with ventricular rate control similarly showed upregulation of alpha SMA protein (approximately 40%, P<0.05), collagen-1 (approximately 380%, P<0.01) and fibronectin-1 (approximately 430%, P<0.001) mRNA versus shams.</AbstractText>Rapidly-paced cardiomyocytes release substances that profoundly alter cardiac fibroblast function, inducing an activated myofibroblast phenotype that is reflected by increased ECM-gene expression in vivo. These findings are consistent with recent observations that AF per se may cause ECM remodeling, and have potentially important consequences for understanding and preventing the mechanisms underlying AF progression.</AbstractText> |
8,413 | Risk factors and predictors of Torsade de pointes ventricular tachycardia in patients with left ventricular systolic dysfunction receiving Dofetilide. | The purpose of this study was to identify risk factors of Torsade de pointes (TdP) ventricular tachycardia in patients medicated with a class III antiarrhythmic drug (dofetilide) and left ventricular systolic dysfunction with heart failure (HF) or recent myocardial infarction (MI). The 2 Danish Investigations of Arrhythmia and Mortality on Dofetilide (DIAMOND) studies enrolled patients with HF (DIAMOND-HF) or MI (DIAMOND-MI) and left ventricular systolic dysfunction. The present analysis includes only patients treated solely with dofetilide. The incidence of TdP was 2.1% (32 of 1,511). Twenty-five of the incidences occurred in the DIAMOND-HF study and 7 cases in the DIAMOND-MI study (p = 0.0015). TdP was more frequent in women than in men (47% vs 28%, p = 0.02). Risk factors for developing TdP were female gender (odds ratio 2.2, 95% confidence interval [CI] 1.0 to 5.0), MI within 8 weeks (odds ratio 0.3, 95% CI 0.1 to 0.7), being in New York Heart Association class III or IV (odds ratio 3.2, 95% CI 1.2 to 8.6), and baseline QTc duration (odds ratio 1.14, 95% CI 1.00 to 1.30) per 10 ms. Women with chronic HF, QTc duration >400 ms. and New York Heart Association class III or IV had a risk of TdP of 10%, whereas no TdP episodes were observed in patients with QTc duration <400 ms. In conclusion, severity of HF, female gender, and QTc duration make it possible to identify patients with a high risk of early TdP when treated with dofetilide. Patients with recent MI less often had TdP compared with patients with chronic HF. |
8,414 | Impact of ramipril on the incidence of atrial fibrillation: results of the Heart Outcomes Prevention Evaluation study. | We evaluated the effect of angiotensin-converting enzyme (ACE) inhibitor ramipril on the incidence of atrial fibrillation (AF) in patients enrolled in the Heart Outcomes Prevention Evaluation trial.</AbstractText>Atrial fibrillation is the most common arrhythmia affecting the general population and is associated with increased morbidity and mortality. Retrospective secondary analyses of some of the large trials of ACE inhibitors have suggested that ACE inhibitors may prevent AF.</AbstractText>We evaluated the occurrence of AF by reviewing the electrocardiogram tracings at entry, at 2 years, and at the end of the study, as well as hospitalizations among 8335 high-risk participants from the Heart Outcomes Prevention Evaluation study, > or = 55 years, without known heart failure or left ventricular (LV) systolic dysfunction and followed for a median period of 4.5 years. We compared the impact of ramipril and matched placebo on occurrence of AF. The results were compared to similar trials.</AbstractText>Over the 4.5 years follow-up, the incidence of new AF was low (2.1%, 177/8335), and ramipril did not significantly reduce the rate of new AF compared with placebo (86/4291 [2.0%] vs 91/4044 [2.2%]) with an odds ratio of 0.92 (95% confidence interval, 0.68-1.24; P = .57). These results added to the previous ACE inhibitor trials (excluding trials in patients with LV dysfunction) showed no significant reduction in new AF among patients treated with these agents (1088/20,930 [5.0%] vs 1343/22,878 [5.9%]; relative risk, 0.92; 95% confidence interval, 0.80-1.05).</AbstractText>Although the incidence of AF was low, treatment with ramipril in this population without known LV systolic dysfunction did not significantly reduce this dysrhythmia.</AbstractText> |
8,415 | Near death and neurocardiogenic syncope. | We report the case of an 18-year-old female who presented as an out-of-hospital ventricular fibrillation cardiac arrest. She required ICD insertion and recovered without deficit. Following recurrent syncopal episodes we diagnosed the co-existence of Neurocardiogenic syncope. |
8,416 | Acute myocardial infarction following the combined use of cocaine and alcohol. | We describe the case of a 37-year-old man who presented with inferior wall myocardial infarction shortly after the concomitant use of cocaine and ethanol. The patient showed prompt ST resolution after thrombolytic therapy. Within two hours from his arrival at the hospital the patient had an episode of ventricular fibrillation, which was successfully treated with electrical cardioversion. Coronary angiography showed normal coronary arteries. The number of patients with acute myocardial infarction after the use of cocaine alone, or in combination with ethanol, is increasing in the USA and other countries; most are young adults. In Greece such cases are still rare, because of the lesser extent of cocaine abuse in the general population and the low sensitivity in recognising cocaine users who present with chest pain in the emergency department. |
8,417 | QT interval prolongation and ventricular fibrillation in childhood end-stage renal disease. | Ventricular arrhythmia is a major cause of death in end-stage renal disease (ESRD). Corrected QT (QTc) interval prolongation, which is one of the predictors of ventricular arrhythmia, may be associated with ESRD. We report an 11-year-old boy who had ESRD with marked QTc interval prolongation and developed torsade de pointes with subsequent ventricular fibrillation during the induction of anesthesia. QTc interval was normalized completely after renal transplantation. |
8,418 | [Effects of defibrillation in the multiple-lead cardiac defibrillation systems on left ventricular function in animal model]. | This study evaluates the immediate effects of the endocardial electrical defibrillation delivered by two transvenous defibrillation systems on left ventricular (LV) function in the animal model. Automatic cardiac defibrillation systems with bipolar leads (group I) and tripolar leads (group II) were placed in the hearts of 10 dogs (group I) and 10 pigs (group II),respectively. Transesophageal echocardiography with two dimensional image, M-mode and pulse Doppler were performed at baseline and after several episodes of defibrillation (DF). Each animal in group 1 underwent 4 DF with 64 Joules; the animals in group2 underwent an average of 8 DF with a total of 210 Joules. LV fractional area contraction, isovolumic relaxation time, and both ratios of velocities and time-velocity integrals in transmitral Doppler flow E and A waves exhibited no significant change after the shocks. This study suggests that the repeated low-energy electrical countershocks delivered by two transvenous defibrillation systems do ndt cause LV global systolic and/or diastolic dysfunction. |
8,419 | Varicella zoster induced cardiac dysfunction: a case report. | A case is presented of cardiac arrhythmia associated with varicella zoster infection, affecting a 34-year-old man. The patient presented with episodes of seizure-like activity, which were subsequently shown to be caused by ventricular fibrillation. The literature regarding this unusual complication of varicella zoster infection is discussed, as it affects both children and adults. Physicians who may face this condition, in accident and emergency, acute medicine, critical care medicine and infectious diseases, should all be aware of this serious complication. |
8,420 | [Same genotype and different phenotypes in a family with PRKAG2 gene mutation]. | The gamma(2) subunit of AMP-activated protein kinase (PRKAG2) located in chromosome 7 plays an important role in regulating metabolic pathways, and patients with PRKAG2 mutations are associated with familial ventricular pre-excitation, hypertrophic cardiomyopathy and AV block. We observed the difference on the phenotypes in a large family with same PRKAG2 mutation.</AbstractText>Direct DNA sequence was performed to screen the exons and exon-intron boundaries of PRKAG2 gene in a large family with 13 affected persons detected by electrocardiography (ECG).</AbstractText>Sinus bradycardia, short PR interval, right bundle bunch block (RBBB), complete AV block, atrial flutter, atrial fibrillation and sudden cardiac death were identified in this family. Hypertrophic cardiomyopathy was found in one family member. Genetic analysis revealed a missense mutation (Arg302Glu) in all affected family members. This mutation was previous described in patients with Wolff-Parkinson-White (WPW) syndrome and hypertrophic cardiomyopathy.</AbstractText>Besides WPW syndrome and hypertrophic cardiomyopathy, PRKAG2 mutations are responsible also for a diverse phenotypes. PRKAG2 gene mutation should be suspected with familial occurrence of RBBB, sinus bradycardia, and short PR interval.</AbstractText> |
8,421 | [Transcoronary ablation of septal hypertrophy versus dual-chamber cardiac pacing for the treatment of aged patients with hypertrophic obstructive cardiomyopathy]. | To compare the safety and efficacy of transcoronary ablation of septal hypertrophy (TASH) versus dual-chamber cardiac pacing (PM) for the treatment of aged > 60 years old) patients with hypertrophic obstructive cardiomyopathy (HOCM).</AbstractText>Medically uncontrolled symptomatic aged patients with hypertrophic obstructive cardiomyopathy (HOCM, n = 23) were treated by transcoronary ablation of septal hypertrophy (TASH, n = 15) or dual-chamber cardiac pacing (PM, n = 8) and followed up for 24 months. Two patients needed permanent pacemaker after TASH were excluded from the analysis.</AbstractText>NYHA class improved from 3.2 +/- 0.7 to 1.5 +/- 0.5 and from 3.0 +/- 0.1 to 1.9 +/- 0.6 and general symptomatic score decreased from 5.9 +/- 1.6 to 1.8 +/- 0.7 and from 4.5 +/- 1.3 to 2.3 +/- 1.6 post TASH or PM treatments, respectively (all P < 0.01 vs. baseline). The decrease of left ventricular outflow pressure gradient (PG) was (80.0 +/- 35.5) mm Hg (1 mmHg = 0.133 kPa) and (49.3 +/- 37.7) mmHg post TASH and PM treatments respectively (all P < 0.05 vs. baseline) and the PG decrease was more significant in TASH group compared to PM group (P < 0.01). Interventricular septal thickness was significantly reduced post TASH [(22 +/- 4) mm vs. (17 +/- 3) mm, P < 0.05] and remained unchanged in PM group. Three patients with paroxysmal atrial fibrillation (2 patients in TASH group and 1 in PM group) developed chronic atrial fibrillation during the follow-up.</AbstractText>Both therapeutic approaches-TASH and PM implantation, significantly reduced PG and significantly improved NYHA class and general symptomatic score in aged symptomatic patients with HOCM. TASH was superior to PM in terms of PG decrease and general symptomatic score improvement.</AbstractText> |
8,422 | Novel electrode design for potentially painless internal defibrillation also allows for successful external defibrillation. | Implantable cardioverter defibrillators (ICDs) save lives, but the defibrillation shocks delivered by these devices produce substantial pain, presumably due to skeletal muscle activation. In this study, we tested an electrode system composed of epicardial panels designed to shield skeletal muscles from internal defibrillation, but allow penetration of an external electric field to enable external defibrillation when required.</AbstractText>Eleven adult mongrel dogs were studied under general anesthesia. Internal defibrillation threshold (DFT) and shock-induced skeletal muscle force at various biphasic shock strengths were compared between two electrode configurations: (1) a transvenous coil placed in the right ventricle (RV) as cathode and a dummy can placed subcutaneously in the left infraclavicular fossa as anode (control configuration) and (2) RV coil as cathode and the multielectrode epicardial sock with the panels connected together as anode (sock-connected). External DFT was also tested with these electrode configurations, as well as with the epicardial sock present, but with panels disconnected from each other (sock-disconnected). Internal DFT was higher with sock-connected than control (24 +/- 7 J vs. 16 +/- 6 J, P < 0.02), but muscle contraction force at DFT was greatly reduced (1.3 +/- 1.3 kg vs. 10.6 +/- 2.2 kg, P < 0.0001). External defibrillation was never successful, even at 360 J, with sock-connected, while always possible with sock-disconnected.</AbstractText>Internal defibrillation with greatly reduced skeletal muscle stimulation can be achieved using a novel electrode system that also preserves the ability to externally defibrillate when required. This system may provide a means for painless ICD therapy.</AbstractText> |
8,423 | Specific antivenom for Bungarus candidus. | Bungarus candidus (Malayan krait) snake is a neurotoxin snake. Previous treatment after snakebite was mainly respiratory support until the patient had spontaneous breathing. Recently specific antivenom for the Bungarus candidus snake was produced by the Queen Saovabha Memorial Institute and distributed in June 2004. The present article is the first report on the clinical response to the specific antivenom for Bungarus candidus.</AbstractText>To analyze the signs and symptoms of patients after snakebite and the response of the patients after receiving specific antivenom for Bungarus candidus snake.</AbstractText>Retrospective chart review.</AbstractText>Four cases of Bungarus candidus snakebite were identified and divided into two groups. Group I (Case 1, 2, and 3) had received specific antivenom for Bungarus candidus while group 2 (case 4) had not. Onset, signs and symptoms after snakebite, antivenom dosage, and response time after receiving antivenom were analyzed.</AbstractText>The first three patients received specific antivenom for Bungarus candidus and the fourth patient did not receive any. All four patients developed neurological signs and symptoms from this neurotoxic venom. In case 1, 2, and 4, the first signs and symptoms were dyspnea, difficulty with speech, and opening the eyelids at 50 minutes (30-60 minutes). The onset ofother signs and symptoms included respiratory paralysis with intubation 3 hours (2-4 hours), full ptosis 3.66 hours (3-4 hours), mydriasis and fixedpupils 4.33 hours (4-5 hours), no response to stimuli 5.66 hours (4-10 hours), tachycardia 5.5 hours (47 hours), and hypertension 14 hours (4-24 hours). The first two patients received specific antivenom for Bungarus candidus after being bitten at 10 and 12 hours, respectively. The first clinical response in case 1, were 12 hours after receiving 16 vials, and in case 2, were 20 hours after receiving 16 vials. These were slight movement of feet phalanxes. At 40 hours after receiving specific antivenom 30 vials in case 1 and 32 vials in case 2, they were able to respond to commands, motor power changed from grade 0 to grade 1 and there was 50% elevated eyebrows. The motor power changedfrom grade I to grade 4 with 100% elevation of eyebrows from full ptosis was 65 hours after receiving specific antivenom 60 vials in case 1 and 70 hours after receiving specific antivenom 87 vials in case 2. The patients had spontaneous opening ofeyelids at 90 hours after receiving 80 vials for case I and 88 hours after receiving 87 vials for case 2. Case 2 was extubated on day 4 after the snakebite while case 1 was extubated later on day 10 because of superimposing pneumonia. The third case had delayed onset of signs and symptoms of neurotoxicity compared to the other three patients. Dyspnea, difficulty with speech, and opening eyelids occurred at 5 hours after the snakebite. No response to stimuli and respiratory paralysis occurred at 20 hours after the snakebite. His consciousness improved 10 hours after receiving 3 vials of specific antivenom. This was noted by being able to respond to commands and the motor power changed to grade 2 however, full ptosis was still present up to 24 hours. After receiving 23 vials ofspecific antivenom, he accidentally extubated himself however, he could breathe adequately using a mask with a bag. His motor power changed to grade 4 with 100% elevated eyebrows but full ptosis 34 hours after receiving 38 vials of specific antivenom. He could spontaneously open his eyelids 40 hours after receiving 38 vials specific antivenom. Cases 1, 2, and 3 had persistent mydriasis andfixed pupils until discharge. Case 4 did not receive specific antivenom for Bungarus candidus. He did not respond to stimuli 10 hours after snakebite and he was treated with respirator and symptomatic treatment. On day 2, his blood pressure dropped, he was on dopamine to raise his BP On day 3, he developed ventricular fibrillation. Defibrillation was administered and ECG returned to normal. He was given further supportive care. On day 7, he was discharged at the request of his relatives without any improvement.</AbstractText>The patients who received specific antivenom had more rapid improvement ofsigns and symptoms comparing to the patient who did not receive the antivenon.</AbstractText> |
8,424 | Ventricular arrhythmias during Tako-tsubo syndrome. | Tako-tsubo syndrome is a recently described form of cardiomyopathy. Its pathophysiology remains unknown. However, the main demographic, clinical, electrocardiographic and biologic characteristics of the disease have been described by previous reports. Retrospective studies are essential to help describe this rare disease, although they might have several skews. Previous reports have observed a mortality rate between 0 and 8%. In our serie, demographic, clinical, electrocardiographic and biologic results are similar with those previously reported. However, the mortality rate observed was higher than expected. Refractory ventricular arrhythmias leading to death have been encountered in 15% of patients. Tako-tsubo syndrome may present as sudden death and its mortality rate may have been underestimated in previous reports. |
8,425 | Rhythms of high-grade block in an ionic model of a strand of regionally ischemic ventricular muscle. | Electrical alternans, a beat-to-beat alternation in the electrocardiogram or electrogram, is frequently seen during the first few minutes of acute myocardial ischemia, and is often immediately followed by malignant cardiac arrhythmias such as ventricular tachycardia and ventricular fibrillation. As ischemia progresses, higher-order periodic rhythms (e.g., period-4) can replace the period-2 alternans rhythm. This is also seen in modelling work on a two-dimensional (2-D) sheet of regionally ischemic ventricular muscle. In addition, in the experimental work, ventricular arrhythmias are overwhelmingly seen only after the higher-order rhythms arise. We investigate an ionic model of a strand of ischemic ventricular muscle, constructed as a 3-cm-long 1-D cable with a centrally located 1-cm-long segment exposed to an elevated extracellular potassium concentration ([K(+)](o)). As [K(+)](o) is raised in this "ischemic segment" to represent one major effect of ongoing ischemia, the sequence of rhythms {1:1-->2:2 (alternans)-->2:1} is seen. With further increase in [K(+)](o), one sees higher-order periodic 2N:M rhythms {2:1-->4:2-->4:1-->6:2-->6:1-->8:2-->8:1}. In a 2N:M cycle, only M of the 2N action potentials generated at the proximal end of the cable successfully traverse the ischemic segment, with the remaining ones being blocked within the ischemic segment. Finally, there is a transition to complete block {8:1-->2:0-->1:0} (in an n:0 rhythm, all action potentials die out within the ischemic segment). Changing the length of the ischemic segment results in different rhythms and transitions being seen: e.g., when the ischemic segment is 2 cm long, the period-6 rhythms are not seen; when it is 0.5 cm long, there is a 3:1 rhythm interposed between the 2:1 and 1:0 rhythms. We discuss the relevance of our results to the experimental observations on the higher-order rhythms that presage reentrant ischemic ventricular arrhythmias. |
8,426 | Antiarrhythmic effect of newly synthesized compound 44Bu on model of aconitine-induced arrhythmia -- compared to lidocaine. | The antiarrhythmic action of the newly developed compound 44Bu (an original compound that was synthesized at our Faculty of Pharmacy) was tested on a model of aconitine-induced arrhythmia and compared with the effect of lidocaine. Both tested substances were administered either as therapeutic or prophylactic agents. 44Bu was highly effective in reducing the occurrence of ventricular fibrillation from 94% to 8% by therapeutic administration, and to 0% by prophylactic administration. The overall mortality rate was significantly reduced by 44Bu from 100% to 25% in the case of therapeutic administration, and to 0% in the case of prophylactic administration. In contrast, there was not any significant difference between therapeutic and prophylactic administration of lidocaine. The occurrence of ventricular fibrillation dropped from 94% to 50% with therapeutic administration, and to 67% with prophylactic administration of lidocaine. The overall mortality rate was significantly reduced from 100% to 63% and to 67%, respectively. We conclude that the 44Bu compound is a highly effective agent in suppressing aconitine-induced arrhythmias. The antiarrhythmic effect of 44Bu was significantly more evident in comparison with lidocaine, particularly in the case of its prophylactic administration. |
8,427 | [Electrotherapy of cardiac failure]. | Intracardiac conduction disturbances, mostly manifested as a left bundle branch block (LBBB), are common findings in cardiac failure and associated with a poor prognosis. LBBB is a marker of disease progression and also leads to worsened cardiac hemodynamics by dyssynchronous contraction that can accelerate progression of the underlying disease. Cardiac resynchronization therapy (CRT) can reduce the negative effects of these disturbances leading to improvement in hemodynamics and long-term improvement in cardiopulmonary exercise tolerance, reduction of left ventricular volumes and functional mitral regurgitation. Prospective multicenter studies, such as the CARE-HF and COMPANION trials have demonstrated reduced mortality with CRT or combined treatment with defibrillator capability (CRT-D). Thus, CRT has been adopted in the current guidelines of cardiology societies. Nevertheless, there are a number of open issues with CRT, such as the high number of non-responders or the value of CRT in patients with atrial fibrillation, narrow QRS complex and mild cardiac failure or asymptomatic left ventricular dysfunction. In addition, the question whether every CRT patient needs a device with defibrillating capabilities is not fully resolved, at least for patients with dilative cardiomyopathy. |
8,428 | Role of maximum rate of depolarization in predicting action potential duration during ventricular fibrillation. | During ventricular fibrillation (VF) only 39% of the variation in action potential duration (APD) is accounted for by the previous diastolic interval [DI((n-1))], i.e., restitution, and the previous APD [APD((n-1))], i.e., memory. We tested the hypothesis that a characteristic of the AP upstroke, the maximum rate of depolarization (V(max)), also helps account for its APD. A floating microelectrode was used to make transmembrane recordings at 16,000 samples/s from the anterior left ventricular wall during four 20-s episodes of VF in each of six pigs. V(max), time from V(max) to 60% repolarization (APD(60)), and DI were calculated throughout all episodes. Stepwise linear regression was used to determine how well each APD(60) (APD(60n)) was predicted by V(max) of that AP, the four previous DIs (n-1, n - 2, n - 3, n - 4), and the three previous APD(60)s (n-1, n - 2, n - 3). V(max) entered in the regression equation significantly more often (86% of VF episodes) than either APD((n-1)) (47% of episodes) or DI((n-1)) (58% of episodes). When these three variables entered first or second, their coefficients were almost always positive, consistent with a longer APD associated with 1) a larger V(max), 2) a longer APD((n-1)), and 3) a longer DI((n-1)). R(2) of the regression for all entered variables was 0.51 +/- 0.01 (mean +/- SD). During the first 20 s of VF in swine, V(max) is a more important determinant of APD than the previous DI (restitution) or the previous APD (memory). All variables together account for only one-half of APD variation during VF. |
8,429 | Spatial distribution of fibrosis governs fibrillation wave dynamics in the posterior left atrium during heart failure. | Heart failure (HF) commonly results in atrial fibrillation (AF) and fibrosis, but how the distribution of fibrosis impacts AF dynamics has not been studied. HF was induced in sheep by ventricular tachypacing (220 bpm, 6 to 7 weeks). Optical mapping (Di-4-ANEPPS, 300 frames/sec) of the posterior left atrial (PLA) endocardium was performed during sustained AF (burst pacing) in Langendorff-perfused HF (n=7, 4 micromol/L acetylcholine; n=3, no acetylcholine) and control (n=6) hearts. PLA breakthroughs were the most frequent activation pattern in both groups (72.0+/-4.6 and 90.2+/-2.7%, HF and control, respectively). However, unlike control, HF breakthroughs preferentially occurred at the PLAs periphery near the pulmonary vein ostia, and their beat-to-beat variability was greater than control (1.93+/-0.14 versus 1.47+/-0.07 changes/[beats/sec], respectively, P<0.05). On histological analysis (picrosirius red), the area of diffuse fibrosis was larger in HF (23.4+/-0.4%) than control (14.1+/-0.6%; P<0.001, n=4). Also the number and size of fibrous patches were significantly larger and their location was more peripheral in HF than control. Computer simulations using 2-dimensional human atrial models with structural and ionic remodeling as in HF demonstrated that changes in AF activation frequency and dynamics were controlled by the interaction of electrical waves with clusters of fibrotic patches of various sizes and individual pulmonary vein ostia. During AF in failing hearts, heterogeneous spatial distribution of fibrosis at the PLA governs AF dynamics and fractionation. |
8,430 | Valvular aortic stenosis in the elderly. | Elderly patients with valvular aortic stenosis have an increased prevalence of coronary risk factors, of coronary artery disease, and evidence of other atherosclerotic vascular diseases. Statins may reduce the progression of aortic stenosis (AS). Angina pectoris, syncope or near syncope, and congestive heart failure are the 3 classic manifestations of severe AS. Prolonged duration and late peaking of an aortic systolic ejection murmur best differentiate severe AS from mild AS on physical examination. Doppler echocardiography is used to diagnose the prevalence and severity of AS. The indications for cardiac catheterization and the medical management of AS are discussed. Once symptoms develop, aortic valve replacement (AVR) should be performed in patients with severe or moderate AS. Other indications for AVR are discussed. Warfarin should be administered indefinitely after AVR in patients with a mechanical aortic valve and in patients with a bioprosthetic aortic valve who have either atrial fibrillation, prior thromboembolism, left ventricular systolic dysfunction, or a hypercoagulable condition. Patients with a bioprosthetic aortic valve without any of these 4 risk factors should be treated with aspirin 75-100 mg daily. |
8,431 | Activation patterns of Purkinje fibers during long-duration ventricular fibrillation in an isolated canine heart model. | The roles of Purkinje fibers (PFs) and focal wave fronts, if any, in the maintenance of ventricular fibrillation (VF) are unknown. If PFs are involved in VF maintenance, it should be possible to map wave fronts propagating from PFs into the working ventricular myocardium during VF. If wave fronts ever arise focally during VF, it should be possible to map them appearing de novo.</AbstractText>Six canine hearts were isolated, and the left main coronary artery was cannulated and perfused. The left ventricular cavity was exposed, which allowed direct endocardial mapping of the anterior papillary muscle insertion. Nonperfused VF was induced, and 6 segments of data, each 5 seconds long, were analyzed during 10 minutes of VF. During 36 segments of data that were analyzed, 1018 PF or focal wave fronts of activation were identified. In 534 wave fronts, activation was mapped propagating from working ventricular myocardium to PF. In 142 wave fronts, activation was mapped propagating from PF to working ventricular myocardium. In 342 wave fronts, activation was mapped arising focally. More than 1 of these 3 patterns could occur in the same wave front.</AbstractText>PFs are highly active throughout the first 10 minutes of VF. In addition to retrograde propagation from the working ventricular myocardium to PFs, antegrade propagation occurs from PFs to working ventricular myocardium, which suggests PFs are important in VF maintenance. Prior plunge needle recordings in dogs indicate activation propagates from the endocardium toward the epicardium after 1 minute of VF, which suggests that focal sites on the endocardium may represent foci and not breakthrough. If so, in addition to reentry, abnormal automaticity or triggered activity may also occur during VF.</AbstractText> |
8,432 | Comparison of N-terminal pro-brain natriuretic peptide versus electrophysiologic study for predicting future outcomes in patients with an implantable cardioverter defibrillator after myocardial infarction. | The aim of the study was to examine the predictive value of N-terminal pro-brain natriuretic peptide (NT-pro-BNP) versus electrophysiologic study in patients with implantable cardioverter-defibrillators (ICDs) after myocardial infarction (MI). We prospectively studied 99 consecutive patients with a history of MI who underwent ICD implantation for primary or secondary prevention of sudden cardiac death. An electrophysiologic study was performed in all patients. Venous blood samples for NT-pro-BNP measurement were obtained at the beginning of the study. The primary end point was ventricular tachycardia or ventricular fibrillation (VT/VF) and the secondary end point was a composite of death, hospitalization for heart failure, or MI. On multivariate Cox regression analysis, NT-pro-BNP level at or greater than median (497 ng/L) was the only significant predictor for VT/VF occurrence (p = 0.047). Along with amiodarone use (p = 0.001), NT-pro-BNP levels higher than median were also associated with a higher risk of composite clinical events (p = 0.036). Kaplan-Meier analysis showed that patients with NT-pro-BNP level at or greater than median had a higher risk of experiencing VT/VF and composite clinical events than patients with NT-pro-BNP levels less than median (log-rank p <0.05). In conclusion, assay of NT-pro-BNP, which is easy to perform and widely available, is superior to electrophysiologic study for prediction of future outcomes in predominantly secondary prophylactic ICD recipients after MI. In the era of primary prophylactic ICD implantation without preimplantation electrophysiologic study, higher NT-pro-BNP levels might help to improve risk-adjusted concomitant antiarrhythmic therapy and device selection. |
8,433 | Sternal fracture and osteomyelitis: an unusual complication of a precordial thump. | Out of hospital cardiac arrest is generally managed by cardiopulmonary resuscitation (CPR) and defibrillation. The precordial thump can also be used in the initial management of witnessed cardiac arrest whilst awaiting direct current cardioversion. However, complications are associated with a precordial thump. We report a case of an out-of-hospital cardiac arrest due to ventricular fibrillation that was treated initially with a precordial thump, which resulted in a sternal fracture and the development of sternal osteomyelitis. |
8,434 | Levosimendan improves the initial outcome of cardiopulmonary resuscitation in a swine model of cardiac arrest. | Cardiac arrest remains the leading cause of death in Western societies. Advanced Life Support guidelines propose epinephrine (adrenaline) for its treatment. The aim of this study was to assess whether a calcium sensitizer agent, such as levosimendan, administered in combination with epinephrine during cardiopulmonary resuscitation, would improve the initial resuscitation success.</AbstractText>Ventricular fibrillation was induced in 20 Landrace/Large-White piglets, and left untreated for 8 min. Resuscitation was then attempted with precordial compressions, mechanical ventilation and electrical defibrillation. The animals were randomized into two groups (10 animals each): animals in Group A received saline as placebo (10 ml dilution, bolus) + epinephrine (0.02 mg/kg), and animals in Group B received levosimendan (0.012 mg/kg/10 ml dilution, bolus) + epinephrine (0.02 mg/kg) during cardiopulmonary resuscitation. Electrical defibrillation was attempted after 10 min of ventricular fibrillation.</AbstractText>Four animals in Group A showed restoration of spontaneous circulation and 10 in Group B (P = 0.011). The coronary perfusion pressure, saturation of peripheral oxygenation and brain regional oxygen saturation were significantly higher during cardiopulmonary resuscitation in Group B.</AbstractText>A calcium sensitizer agent, when administered during cardiopulmonary resuscitation, significantly improves initial resuscitation success and increases coronary perfusion pressure during cardiopulmonary resuscitation.</AbstractText> |
8,435 | Torsades de pointes and self-terminating ventricular fibrillation in a prescription methadone user. | Methadone is known to prolong the QT interval and precipitate torsades de pointes. A 54-year-old prescription methadone user with hypokalaemia was referred to Critical Care with acute confusion and respiratory distress. Alcohol withdrawal was the presumed precipitant. The real precipitant only became evident on analysis of a 24-h ECG (Holter monitor) attached to the patient at the time. The patient had suffered prolonged (10 min) ventricular arrhythmias including torsades de pointes and self-terminating ventricular fibrillation. The patient made a full recovery. Risk factors for acquired long QT syndrome and the treatment of torsades de pointes are discussed. |
8,436 | Noninvasive ECG as a tool for predicting termination of paroxysmal atrial fibrillation. | Atrial fibrillation (AF) is the most common cardiac arrhythmia and entails an increased risk of thromboembolic events. Prediction of the termination of an AF episode, based on noninvasive techniques, can benefit patients, doctors and health systems. The method described in this paper is based on two-lead surface electrocardiograms (ECGs): 1-min ECG recordings of AF episodes including N-type (not terminating within an hour after the end of the record), S-type (terminating 1 min after the end of the record) and T-type (terminating immediately after the end of the record). These records are organised into three learning sets (N, S and T) and two test sets (A and B). Starting from these ECGs, the atrial and ventricular activities were separated using beat classification and class averaged beat subtraction, followed by the evaluation of seven parameters representing atrial or ventricular activity. Stepwise discriminant analysis selected the set including dominant atrial frequency (DAF, index of atrial activity) and average HR (HRmean, index of ventricular activity) as optimal for discrimination between N/T-type episodes. The linear classifier, estimated on the 20 cases of the N and T learning sets, provided a performance of 90% on the 30 cases of a test set for the N/T-type discrimination. The same classifier led to correct classification in 89% of the 46 cases for N/S-type discrimination. The method has shown good results and seems to be suitable for clinical application, although a larger dataset would be very useful for improvement and validation of the algorithms and the development of an earlier predictor of paroxysmal AF spontaneous termination time. |
8,437 | Reduced thyrotropin in euthyroid goitrous patients suggesting subclinical hyperthyroidism. | Subclinical hyperthyroidism, a biochemical finding of low serum thyrotropin (TSH) with the serum levels of thyroxine (T4) and triiodothyronine (T3) within the reference range, could easily be ignored by clinicians, as it, usually, does not manifest with any thyroid specific symptoms. It is of two types: endogenous and exogenous. However, patients with the findings of low TSH, normal T4 and T3 develop some abnormalities in the cardiovascular system, such as atrial fibrillation, increase in left ventricular mass and diastolic dysfunction. It is believed that treatment intervention may reduce or halt the progression of the cardiac abnormalities. The main objective of the study was to determine how frequent subclinical hyperthyroidism was occurs and to serve as a reminder to the existence of the disorder.</AbstractText>It was a hospital-based study carried out at the Jos University Teaching Hospital (JUTH). Consecutive clinically euthyroid goitre patients attending the outpatient department of JUTH, were studied for various parameters including TSH, T4 and T3 The serum concentrations of T4 and T3 were determined by enzyme-linked immunosorbent assay (ELISA) technique. The serum TSH concentration was estimated using a 2nd generation ELISA technique.</AbstractText>98 patients participated in the study. Nine patients had non-specific symptoms not referable to the thyroid and found to have high levels of thyroid hormone concentration with depressed TSH and were excluded from further analysis, while 7 had subclinical hyperthyroidism giving a prevalence rate of 7.9% among these clinical euthyroid goitre patients. The subjects with this condition were mainly above 60 years of age and mainly had long-standing goitre.</AbstractText>Endogenous subclinical hyperthyroidism was present in 7.9% of these clinically euthyroid goitre patients mainly 60 years and above, with long-standing goitre. This high prevalence rate calls for high index of suspicion as this condition is associated with morbidities that can raise mortality.</AbstractText> |
8,438 | What cardioversion protocol for ventricular fibrillation should be followed for patients who arrest shortly post-cardiac surgery? | A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was how many cardioversion attempts should be performed for patients who have gone into ventricular fibrillation post-cardiac surgery prior to performing chest reopening. Using the reported search, 1183 papers were identified. Fifteen papers represented the best evidence on the subject. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study comments and weaknesses were tabulated. The quality and level of evidence was assessed using the International Liaison Committee of Resuscitation guideline recommendations. The most recent European Resuscitation Council guidelines suggest single attempts at cardioversion, spaced at 2-min intervals, for all patients going into ventricular fibrillation or pulseless ventricular tachycardia. Cardiac surgery presents a unique challenge for these guidelines in that emergency re-sternotomy may provide additional lifesaving interventions once it is deemed that external cardioversion is unlikely to succeed. The 15 papers identified demonstrated that the success of the first attempt at cardioversion for VF/VT was around 78%. The chance of the second shock succeeding was around 35%. The chance of a third shock succeeding was 14%. Very little data were found on the chance of further shocks succeeding. Of note none of these papers were in patients on the intensive care after cardiac surgery. We conclude that, due to the importance of minimising the delay to chest reopening, three shocks should be quickly delivered. If these do not succeed the chance of a 4th shock succeeding is likely to be <10% and, thus, immediate chest reopening should be performed. (This is a Class-IIa recommendation using ILCOR guideline recommendations.). |
8,439 | Out-of-hospital cardiac arrest caused by transient left ventricular apical ballooning syndrome. | We describe a case of out-of-hospital cardiac arrest due to ventricular fibrillation in a patient with transient left ventricular apical ballooning syndrome. Our report confirms that left ventricular apical ballooning may have the same complications of myocardial infarction, adding the early ventricular fibrillation to the previous findings of left ventricular wall rupture, ventricular arrhythmias during hospitalization and complete atrio-ventricular block. Moreover, left ventricular apical ballooning may have different and unusual clinical onsets, including sudden cardiac death due to ventricular tachyarrhythmias in the absence of associated symptoms. Therefore, in our opinion left ventricular apical ballooning may be considered as a possible cause of sudden death in otherwise healthy women. |
8,440 | Bradycardia pacing-induced short-long-short sequences at the onset of ventricular tachyarrhythmias: a possible mechanism of proarrhythmia? | The purpose of this study was to characterize interactions between normal pacing system operation and the initiating sequence of ventricular tachycardia (VT)/ventricular fibrillation (VF).</AbstractText>Abrupt changes in ventricular cycle lengths (short-long-short, S-L-S) might initiate VT/VF. The S-L-S sequences might be passively permitted or actively facilitated by bradycardia pacing.</AbstractText>Initiating sequences of 1,356 VT/VF episodes in the PainFree Rx II (n = 634) and EnTrust Trial (n = 421) were analyzed with stored electrograms and by pacing mode (DDD/R, VVI/R, and Managed Ventricular Pacing [MVP]). Interactions between pacing and VT/VF initiation were classified as: non-pacing associated, pacing associated, pacing permitted, and pacing facilitated.</AbstractText>Non-pacing associated (no pacing, no S-L-S) and pacing associated (ventricular pacing without S-L-S) onset accounted for 44.0% and 29.8% of all VT/VF, respectively. Pacing permitted (S-L-S sequences without ventricular pacing) episodes accounted for 6.4% (DDD/R), 20.0% (MVP), and 25.6% (VVI/R) of 1,356 VT/VF episodes. Pacing facilitated onset (S-L-S sequences actively facilitated by ventricular pacing including the terminal beat after a pause) accounted for 8.2% (MVP), 9.4% (VVI/R), and 14.8% (DDD/R) of 1,356 VT/VF episodes. Pacing facilitated S-L-S VT/VF occurred in 2.6% (MVP), 3.3% (VVI/R), and 5.2% (DDD/R) of patients with episodes and was the sole initiating sequence in approximately 1% of patients. Pause durations during pacing facilitated S-L-S differed between modes (DDD/R 793 +/- 172 ms vs. MVP 865 +/- 278 ms vs. VVI/R 1180 +/- 414 ms, p = 0.002). The majority of these episodes were monomorphic VT.</AbstractText>Ventricular tachycardia/VF in some implantable cardioverter-defibrillator patients might be initiated by S-L-S sequences that are actively facilitated by bradycardia pacing operation and might constitute an important mechanism of ventricular proarrhythmia.</AbstractText> |
8,441 | Surgical treatment of arrhythmias in adults with congenital heart defects. | Supraventricular and ventricular arrhythmias are a major cause of morbidity and mortality in adult patients with congenital heart disease (CHD). Intraoperative ablation offers an alternative to the complex surgical Cox-Maze procedure for these patients. We present the results of our preliminary experience with intraoperative monopolar irrigated radiofrequency ablation (IRA) in adults with CHD undergoing elective cardiac surgery.</AbstractText>Since September 2002, 50 adults with a mean age of 39 years with CHD underwent IRA during cardiac surgery. We performed 31 right-sided Maze procedures, 13 Cox-Maze III procedures and 6 right ventricular ablations. In addition, we implanted a pace-maker into 14 patients.</AbstractText>Two patients died (2 of 50; 4%) of causes not related to the intraoperative ablation. Over an average follow-up period of 28 months the remaining 48 patients are alive in NYHA class I or II. All patients were discharged on antiarrhythmic oral treatment for 3 months. All patients underwent Holter testing 3 and 6 months after the ablation procedure and five underwent programmed ventricular tachycardia stimulation 6 months postoperatively. Forty-three patients are still in spontaneous sinus rhythm, two are in sinus rhythm on chronic oral antiarrhythmic treatment for recurrence of atrial fibrillation, two are in stable atrial fibrillation, and one has pacemaker rhythm. There were no complications from the IRA.</AbstractText>Intraoperative IRA is a safe and effective procedure to control arrhythmic problems in adults with CHD. This procedure should be taken into consideration when transcatheter ablation fails or when elective cardiac surgery is planned.</AbstractText> |
8,442 | Real-time monitoring of cardiac metabolism using biosensors shows myocardial protection during ischemia-reperfusion injury with glucose-insulin-potassium administration. | Systemic infusion of glucose-insulin-potassium (GIK) is thought to confer myocardial protection during ischemia-reperfusion injury. Our laboratory has experience with real-time monitoring of glucose and pH levels using needle-mounted biosensors. We tested the hypothesis that GIK enhances myocardial metabolism as displayed by real-time myocardial metabolic monitoring.</AbstractText>A total of 40 kg male swine were randomized to receive GIK (n = 7) or lactated Ringer's (n = 7) solution intravenously at 1.5 mL/kg/hour. Ischemia was induced in the left anterior distribution (LAD) by 20 minutes LAD occlusion, followed by 20 minutes reperfusion. Hearts were instrumented anteriorly and posteriorly with continuously recording myocardial pH and glucose biosensors. Biopsies from the LAD distribution were taken at baseline, maximum ischemia, and after reperfusion to assess cardiac adenosine triphosphate (ATP) levels.</AbstractText>GIK animals had less myocardial pH decrease than controls during both ischemia (pH decrease -0.03 vs -0.37, P = .04) and reperfusion (pH decrease -0.10 vs -0.44, P = .05). Neither ATP (74% vs 73% decrease from baseline) nor glucose (27% vs 33% decrease from baseline) varied significantly between groups during ischemia. GIK animals had faster normalization of ATP (100% vs 79% increase from ischemia) and glucose (69% vs 28% increase from ischemia) during reperfusion.</AbstractText>Real-time myocardial metabolic monitoring shows that cardiac pH is improved by GIK during ischemia-reperfusion injury; however, ATP and glucose levels were not significantly enhanced. GIK animals trended toward earlier recovery during reperfusion. Mediators of this metabolic enhancement need to be explored.</AbstractText> |
8,443 | [Epidemiology and new predictors of atrial fibrillation after coronary surgery]. | Postoperative atrial fibrillation (PAF) is a frequent complication of coronary artery bypass grafting (CABG). Our aims were to study its epidemiology and to identify predictors in everyday clinical practice, while taking into account statin use, extracorporeal circulation, and new biomarkers of inflammation and ventricular stress.</AbstractText>The study included 102 consecutive patients (65 [9] years, 72% male) who were undergoing CABG. Blood samples were taken the day before surgery to determine baseline levels of C-reactive protein (CRP) and N-terminal probrain natriuretic peptide (NT-proBNP). Details of baseline clinical characteristics, preoperative treatment and surgery were recorded. The end-point was PAF at 30 days.</AbstractText>The incidence of PAF was 23% (n=23; 3.2 [2.9] days, range 1-15 days). Its appearance was associated with a longer stay in the intensive care unit (+ 1 day; P=.019), but not with an increased total hospital stay (P=.213). Among patients with PAF, 4.3% had an embolism and 8.6% remained in atrial fibrillation at discharge. Moreover, PAF was associated with a longer duration of ischemia (28.5 [22.3] vs 18.0 [27.9]; P=.045) and a lower statin pretreatment rate (39% vs 66%; P=.022). Multivariate analysis showed that the only factor associated with a higher risk of PAF was the absence of statin pretreatment (odds ratio = 4.31, 95% confidence interval 1.33-13.88; P=.015). There was no association between either extracorporeal circulation or the baseline CRP or NT-proBNP level and an increased risk of PAF.</AbstractText>In everyday clinical practice, PAF is a frequent complication. Statin pretreatment could have a protective effect against its appearance.</AbstractText> |
8,444 | [Risk stratification of asymptomatic subjects using resting ECG and stress ECG]. | The resting electrocardiogram (ECG) and stress ECG are established tests in the array of cardiovascular diagnostic modalities. In addition to their diagnostic value for structural heart disease and rhythm disorders, ECGs at rest or during stress also contain prognostically relevant information. Several ECG abnormalities, e.g., left ventricular hypertrophy (LVH), Q waves, ST segment changes, left bundle branch block, atrial fibrillation or QT interval prolongation, were shown to be associated with cardiovascular events. Differences in study design, the cohorts of investigation and morphological definitions of ECG abnormalities may in part be responsible for the abnormalities not being implemented in risk stratification algorithms. The non-ST-segment-related variables in stress testing, e.g., functional capacity, chronotropic (in)competence, heart rate (HR) recovery, and the HR/ST index and slope, could be identified as prognostically relevant markers in population-based studies. For many of these resting and stress ECG-based abnormalities, associations with the extent of subclinical atherosclerosis in persons without established coronary heart disease were observed, indicating a preclinical relationship between epicardial atherosclerosis and myocardial pathology. The resting and the stress ECG provide a number of prognostically relevant indices that can easily be obtained in routine clinical practice, but have thus far found little acceptance for risk stratification of asymptomatic individuals. |
8,445 | The effect of angiotensin receptor blockers for preventing atrial fibrillation. | Atrial fibrillation is the most common sustained cardiac arrhythmia in clinical practice, and causes significant burden to patients and health care systems. Clinicians treat existing atrial fibrillation with anticoagulation and/or drugs that utilize either a rate or rhythm control strategy. It remains unclear how best to reduce cardiovascular morbidity and mortality in this population. Prevention of atrial fibrillation using angiotensin receptor blockers, which affect ion currents and refractoriness in atrial myocytes, regress or prevent atrial fibrosis, decrease left atrial size, regress left ventricular hypertrophy, modulate sympathetic nerve activity, reduce inflammation, and reduce blood pressure, may become an important and desirable alternative. |
8,446 | [Takotsubo cardiomyopathy associated with torsades de pointes and long QT interval: a case report]. | A 77-year-old man was admitted to our hospital for pneumonia. On admission, electrocardiography showed ST segmental elevation and echocardiography showed abnormal movement of the left ventricular walls. Emergent coronary angiography was not performed because of his high C-reactive protein values and negative troponin T value. On the 3rd day, electrocardiography showed torsades de pointes and long QT interval, then intravenous lidocaine (1,000 mg/day) was started. Left ventriculography demonstrated takotsubo cardiomyopathy on the 9th day. Torsades de pointes disappeared with intravenous lidocaine therapy, and he was discharged on the 27th day. Takotsubo cardiomyopathy has a relatively good prognosis, and rarely causes sudden death and congestive heart failure. Ventricular tachycardia and fibrillation complicate this disease in 9% of patients. To prevent fatal arrhythmia, appropriate therapy against torsades de pointes should be considered. |
8,447 | [Primary aldosteronism with ventricular fibrillation: a case report]. | A 60-year-old female had sudden onset of syncope. The emergency service noticed that she suffered cardiopulmonary arrest (ventricular fibrillation: VF). After defibrillation in the ambulance, she was transported to our emergency department. Electrocardiography monitoring showed QT prolongation. Serum potassium level was extremely low at 1.8 mEq/l. Although potassium and lidocaine were administered, it was difficult to maintain appropriate electrolyte balance and prevent VF after admission, so temporary overdrive pacing was required. She was diagnosed as having primary aldosteronism after laboratory and imaging examinations. VF was otherwise uncontrollable so a cardioverter defibrillator was implanted on the 24th hospital day. Laparoscopic adrenalglandectomy was performed about 1 month later. After the surgery, serum potassium level remained at an appropriate level without medication. No severe neurological deficits were found at discharge from our hospital. |
8,448 | [Assessment of pathophysiology based on the left ventricular shape in five patients with midventricular obstructive hypertrophic cardiomyopathy]. | The pathophysiology of midventricular obstructive hypertrophic cardiomyopathy (MVO) is unknown. Patients with MVO and MVO-like cardiomyopathy were classified into three groups based on the cardioimaging morphological characteristics of the left ventricle to investigate their complications and treatment.</AbstractText>Four patients with MVO and one patient with disease-like MVO were admitted in our hospital from 1999 to 2005. Group A consisted of one patient with indications of pressure gradient at mid-ventricle without apical aneurysm, Group B consisted of three patients with indications of pressure gradient and apical aneurysm, and Group C consisted of one patient with hour-glass appearance with apical aneurysm and decreased left ventricular systolic function without pressure gradient.</AbstractText>The diagnosis was established during examination for sustained ventricular tachycardia (SVT, three patients), paroxysmal atrial fibrillation (one patient), and coronary artery disease (one patient). Cardiogenic embolization was observed in all cases which originated from atrial fibrillation (one case) and apical aneurysm (two cases). No embolic event occurred in any patient after warfarin therapy. SVT occurred in patients in Groups B and C. SVT refractory to beta-blocker and mexiletine was treated by amiodarone. Apical aneurysmectomy and cryoablation could prevent recurrent SVT with drug resistance.</AbstractText>Four of the five patients with MVO had arrhythmia (atrial fibrillation, SVT) and three had cardiogenic embolization. MVO could be classified into three groups depending on the morphological characteristics and complications. Treatment of MVO should be based on these characteristics.</AbstractText> |
8,449 | Digoxin and mortality in atrial fibrillation: a prospective cohort study. | The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study showed that rhythm-control treatment of patients with atrial fibrillation (AF) offered no survival advantage over a rate-control strategy. In a subgroup analysis of that study, it was found that digoxin increased the death rate [relative risk (RR) = 1.42), but it was suggested that this may have been attributable to prescription of digoxin for patients at greater risk of death, such as those with congestive heart failure (CHF). No study has investigated a priori the effect of digoxin on mortality in patients with AF. This study aimed to address this question.</AbstractText>Using data from the Registry of Information and Knowledge about Swedish Heart Intensive care Admissions (RIKS-HIA), we studied the 1-year mortality among patients admitted to coronary care units with AF, CHF, or AF+CHF with or without digoxin (n = 60,764) during 1995-2003. Adjustment for differences in background characteristics and other medications and treatments was made by propensity scoring.</AbstractText>Twenty percent of patients with AF without CHF in this cohort were discharged with digoxin. This group had a higher mortality rate than the corresponding group not given digoxin [adjusted RR 1.42 (95% CI 1.29-1.56)], whereas no such difference was seen among patients with CHF with or without AF, although these patients had a nearly three-times higher mortality.</AbstractText>The results suggest that long-term therapy with digoxin is an independent risk factor for death in patients with AF without CHF.</AbstractText> |
8,450 | Defibrillation testing of the implantable cardioverter defibrillator: when, how, and by whom? | The implantable cardioverter-defibrillator (ICD) has become an integral part of treatment for a variety of patients with symptomatic, or at risk for, ventricular tachyarrhythmias. The ICD's effectiveness is attributed to its ability to promptly detect and terminate ventricular tachycardia (VT) and fibrillation (VF). The clinical trials that established the positive role of ICD therapy were based on patients who underwent some form of defibrillation testing at the time of implantation. Therefore, since its advent, intraoperative defibrillation testing of the ICD to assure reliable detection and termination of VT/VF has been a standard practice. But because of advances in defibrillator and lead technology, which now facilitates successful device implantation (i.e., low defibrillation energy requirement to allow for an adequate programmed safety margin) in the majority of patients, the necessity of defibrillation testing has been called into attention. Despite substantial progress, it is not altogether clear whether a wholesale abandonment of intraoperative ICD testing is appropriate at this point. We review pertinent data regarding pros and cons of ICD testing and offer a suggestion as to when, how, and who should test ICDs. |
8,451 | Evolution of left atrial systolic and diastolic functions in different stages of hypertension: distinct effects of blood pressure control. | To evaluate the left atrial (LA) volume, and LA systolic (contractile) and diastolic (expansion) functions in different stages of hypertension with or without atrial fibrillation (AF), as well as the effects of good blood pressure control.</AbstractText>A prospective observational study. Individuals including 22 normotensive controls, 23 patients with mild hypertension, 20 with severe hypertension, and 17 with hypertension and paroxysmal AF were recruited for paired echocardiography studies at baseline and 6 months after control of hypertension.</AbstractText>With increasing severity of hypertension, left ventricular (LV) diastolic function deteriorated with decreasing LV septal E'/A' and increasing E/E' ratios. LA expansion index was reduced in parallel. LA expansion index was correlated positively with LV E'/A' (r = 0.43, p = 0.022) and inversely with LV E/E' (r = 0.49, p = 0.009). Significant improvement of LV diastolic function and LA expansion index preceded the reduction of LA volume after blood pressure control. In patients with paroxysmal AF, LA volume reduction was more evident in patients receiving angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers.</AbstractText>With progressive LV diastolic dysfunction in hypertension, there was a corresponding deterioration in LA diastolic function. Effective blood pressure control for 6 months improved LA diastolic function.</AbstractText>Copyright 2007 S. Karger AG, Basel.</CopyrightInformation> |
8,452 | Effects of protein kinase C activation on cardiac repolarization and arrhythmogenesis in Langendorff-perfused rabbit hearts. | Cardiac arrhythmias are still a major cause of mortality in western countries. Currently available antiarrhythmic drugs are limited by a low efficacy and proarrhythmic effects. The role of the protein kinase C (PKC) signalling pathway in arrhythmogenesis is still unclear. The goal of the present study was to test the effects of PKC stimulation on whole heart electrophysiology and its pro-/antiarrhythmic activity.</AbstractText>Left ventricular (LV) action potential duration (APD 90%) was determined in 27 Langendorff-perfused rabbit hearts, using Tyrode solution plus the PKC agonist phorbol-12-myristate-13-acetate (PMA; 100 nM) alone (nine rabbits), Verapamil alone (n = 6), or PMA in combination with Verapamil (0.25 mg/L, six rabbits), or bisindolylmaleimide (0.5 microM, n = 6). Intermittent programmed extra-stimulation was performed to induce ventricular arrhythmias. Administration of PMA alone led to a significant shortening of repolarization (APD 90%, 157 +/- 8 vs. 128 +/- 5 ms, P<0.05). Non-sustained ventricular fibrillation (VF) could be induced in seven out of nine animals. After perfusion of Verapamil (156 +/- 6 vs. 169 +/- 4 ms, P>0.05) or bisindolylmaleimide, a selective inhibitor of PKC (136 +/- 4 vs. 146 +/- 4 ms, P>0.05), PMA-induced shortening of repolarization could be inhibited, and induction of VF failed. Verapamil alone did not affect APD and VF could not be induced.</AbstractText>Activation of PKC facilitates induction of VF, which is most likely due to a shortening of repolarization and a prominent calcium influx. These findings demonstrate involvement of the PKC-signalling pathway in arrhythmogenesis.</AbstractText> |
8,453 | The BRIGHT study: bifocal right ventricular resynchronization therapy: a randomized study. | The BRIGHT study evaluated bifocal right ventricular (RV) (apex and outflow tract) pacing in a single, blind, randomized crossover study in patients eligible for cardiac resynchronization therapy (CRT). Forty-two patients were enrolled with the following characteristics: chronic drug refractory heart failure New York Heart Association (NYHA) class III-IV; ejection fraction (EF)<35%; QRS width >or= 120 ms; and a left bundle branch block. The aim of the study was to assess an improvement in left ventricular (LV) EF, 6 min walk test, Minnesota quality-of-life score, and NYHA classification. Methods and result Patients were randomized to receive either bifocal pacing or the control mode, each for a period of 3 months. Parameters were measured prior to randomization and after 3 months of control or bifocal pacing. Eight patients failed to make the 7 month follow-up, three patients died (one prior to randomization at the first month), five patients dropped out, and three patients refused further participation. One patient had a persistent lead problem, which was subsequently replaced with an LV lead, and one patient suffered with persistent atrial fibrillation. Compared with baseline, bifocal pacing improved EF from 26 +/- 12% to 36 +/- 11% (P < 0.0008), NYHA classification decreased from 2.8 +/- 0.4 to 2.3 +/- 0.7 (P < 0.007). Furthermore, the 6 min walk test improved from 372 +/- 129 m to 453 +/- 122 m (P < 0.05), and the Minnesota Living with Heart Failure scores decreased from 33 +/- 20 to 24 +/- 21 (P < 0.006). In the control group, no significant changes in any parameters were observed. Eight patients did not tolerate reprogramming from DDD BRIGHT to control pacing, with symptoms disappearing in all patients after reprogramming to bifocal pacing.</AbstractText>Bifocal RV pacing in patients with a classic indication for CRT shows improvement in all parameters.</AbstractText> |
8,454 | [Cardioversion and atrial stunning]. | Stunned atrium is defined as a state of temporary mechanic atrial dysfunction with preserved bioeletrical function. It may follow up to 38-80% successful cardioversions performed to convert atrial fibrillation to regular sinus rhythm. Lack of effective atrial contractility leads to hemodynamic changes, which may result in thrombus formation with subsequent thromboembolic events. It becomes a priority to research in depth the pathophysiology of stunned atrium phenomenon and form strategies to avoid complications associated with it. Studies have shown, that even patients who had no evidence of thrombotic material (as proven by transesophageal echocardiography performed prior to cardioversion), are still at increased risk of embolic events. This fact created basis for hypothesis, that conditions for clot formation may be met only when sinus rhythm is restored. 93% of thrombi are accompanied by so-called spontaneous contrast phenomenon. The purpose of our study was to find relations between factors contributing to stunned atrium and its cellular mechanisms. It is suggested, that stunned atrium results from changes in atrial muscular membrane which occur during atrial fibrillation. Stunned atrium is encountered more frequently in patients with coronary artery disease than in hypertensive heart disease or even lone atrial fibrillation. It is also associated with rheumatic valvular abnormalities and left ventricular dysfunction from other causes. Studies have shown no correlation between the frequency of stunned atrium and the mode of cardioversion. It was observed, that duration of atrial fibrillation and dimensions of atria have substantial impact on time to mechanical function recovery and magnitude of atrial stunning. Studies on subjects undergoing cardioversion due to atrial fibrillation proved that there is a higher tendency to stunned atrium in patients with atrial enlargement. Due to significant delay until full mechanical function recovery, it is of prominent importance to continue anticoagulation for at least 4 weeks after cardioversion. |
8,455 | [Clinical variants of Churg-Strauss eosinophilic vasculitis]. | The purpose of the study was to analyze clinical variants of eosinophilic vasculitis (EV). The authors observed 12 EV patients (five men and seven women; mean age 43 +/- 5.7) during a ten-year period. Two of the patients died of ventricular fibrillation due to myocarditis and of mesenterial thrombosis. Clinical variants of EV were diverse. The main syndromes in EV were: predominant lesion of the pulmonary system with polyneuropathy; lesion of the gastrointestinal tract (GIT) with eosinophilia; lesion of the cardiovascular system as well as association with other rheumatologic conditions (rheumatoid arthritis and diffuse eosinophilic fasciitis). The main therapeutic regimens in EV include steroidal therapy in medium to large doses, cyclophosphan intramuscularly, and intensive care--pulse therapy with metipred and plasmapheresis. Analysis of the results of the treatment of these patients demonstrated the efficacy of cyclophosphan administered in doses of approximately 2300 mg per course intramuscularly in combination with prednisolone (more than 40 mg a day), plasmapheresis (more than three sessions per a course), antiaggregants, heparin (more than 18000 units a day) and general hyperbaric oxygenation, as well as pulse therapy with metipred in a dose of 2200 mg per three days as intravenous infusion. The prognosis of EV was most poor in cases of lesion of the cardiovascular system and the GIT. |
8,456 | Ventricular fibrillation in late recovery after dobutamine stress echocardiography. | A 62-year-old man with multiple cardiac risk factors, including diabetes mellitus type II, treated hypertension, and hyperlipidemia, had a dobutamine stress echocardiogram performed as part of a preoperative evaluation. At peak stress the patient developed an apical regional wall motion abnormality. Approximately 12 minutes into the recovery period, the patient developed ventricular tachycardia that degenerated into ventricular fibrillation. He was successfully resuscitated and underwent emergency coronary angiography that showed a 95% distal left anterior descending coronary artery stenosis. |
8,457 | Can atrial vagal denervation influence ventricular function in a failing heart? | Atrial fibrillation (AF) and congestive heart failure (CHF) often coexist (AF-CHF), and each adversely affects the other with respect to management and prognosis. Therapy with antiarrhythmic drugs to maintain sinus rhythm was disappointing. Ablation is more successful than antiarrhythmic drug therapy for the prevention of AF with few complications, although in patients with AF-CHF it is noted. Ablating autonomic nerves and ganglia on the large vessels and the heart can result in AF suppression with little damage to healthy myocardium. Our study in patients with AF-CHF found that cardiac function aggravation was more frequent in patients with AF recurrence than that of those who successfully maintain sinus rhythm. The autonomic nervous system is a fine network spreading throughout the myocytes; hence the elimination of atrial vagal with radiofrequency catheter ablation can influence the innervation in sinus and AV nodes even in the ventricular region. Thus we propose that atrial vagal denervation may result in paratherapeutic sympathovagal imbalance in the ventricular region, which has a negative effect in a failing heart, although it is neutralized by the benefit accrued from sinus rhythm after successful ablation. |
8,458 | Inflammatory biomarkers are not predictive of intermediate-term risk of ventricular tachyarrhythmias in stable CHF patients. | Elevated levels of inflammatory biomarkers and brain natriuretic peptide (BNP) are associated with increased mortality in patients with heart failure (HF).</AbstractText>: The aim of the current study was to assess the correlation between circulating biomarkers and ventricular tachyarrhythmias among patients with HF.</AbstractText>Blood samples from 50 stable ambulatory HF patients with moderate to severe systolic left ventricular (LV) dysfunction and an implantable cardioverter defibrillator (ICD) were analyzed for interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), high-sensitivity C-reactive protein (hsCRP) and BNP. Thereafter, the patients were followed for a mean period of 152 +/- 44 days, during which ventricular tachyarrhythmias were recorded by the ICDs.</AbstractText>Follow-up data were obtained from 47 patients. Of them, 45 (96%) had ischemic cardiomyopathy, 38 (81%) had New York Heart Association class I-II, 43 (91%) were males, and the mean age was 68.6 +/- 11.1 years. During follow-up, 5 patients (11%) had nonsustained ventricular tachycardia (NSVT), 6 patients (13%) had sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and 36 patients (76%) had no events. The circulating biomarkers' levels upon enrollment were not significantly different between patients who subsequently had NSVT or VT/VF and patients who were free of events.</AbstractText>No correlation was found between plasma levels of IL-6, TNF-alpha, hsCRP and BNP and ventricular arrhythmic events among stable HF patients during an intermediate term follow-up of 5.1 months. Further studies are still required to assess the association between these biomarkers and long-term risk of ventricular tachyarrhythmia.</AbstractText>(c) 2007 Wiley Periodicals, Inc.</CopyrightInformation> |
8,459 | Prevention of ventricular fibrillation requires central beta-adrenoceptor blockade in rabbits. | To study whether and how a lipophilic and a hydrophilic beta-adrenoceptor antagonist affects ventricular fibrillation (VF) after coronary artery occlusion in a rabbit model with high sympathetic and low cardiac vagal activation.</AbstractText>Rabbits were treated for 3 weeks (series 1) or 2 hours (series 2) with metoprolol, atenolol or control vehicle. Finally the animals in series 1 were exposed to coronary artery occlusion. Heart rate response to cholinergic blockade was studied in series 2.</AbstractText>The incidence of postocclusion VF in metoprolol animals was lower (p<0.05) than that in atenolol or control animals. The two beta-blockers caused similar reductions of heart rate, arterial pressure and myocardial ischemia. However, metoprolol animals had more respiratory sinus arrhythmia higher baroreflex sensitivity and more pronounced tachycardic response to cholinergic blockade than atenolol animals.</AbstractText>Metoprolol reduced the incidence of VF by a better maintained discharge than atenolol in efferent cardiac vagal nerves, possibly due to inhibition of central nervous beta(1) adrenoceptors modulating vagal nervous outflow.</AbstractText> |
8,460 | Novel mutation in the SCN5A gene associated with arrhythmic storm development during acute myocardial infarction. | Ventricular tachycardia (VT) and ventricular fibrillation (VF) complicating Brugada syndrome, a genetic disorder linked to SCN5A mutations, and VF complicating acute myocardial infarction (AMI) both have been linked to phase 2 reentry.</AbstractText>Given the mechanistic similarities in arrhythmogenesis, the purpose of this study was to examine the contribution of SCN5A mutations to VT/VF complicating AMI.</AbstractText>Nineteen consecutive patients developing VF during AMI were enrolled in the study. Wild-type (WT) and mutant SCN5A genes were coexpressed with SCN1B in TSA201 cells and studied using whole-cell patch clamp techniques.</AbstractText>Among the cohort of 19 patients, one missense mutation (G400A) in SCN5A was detected in a conserved region. An H558R polymorphism was detected on the same allele. Unlike the other 18 patients, who each developed 1-2 VF episodes during AMI, the mutation carrier developed six episodes of VT/VF within the first 12 hours. All VT/VF episodes were associated with ST-segment changes and were initiated by short-coupled extrasystoles. Flecainide and adenosine challenge performed to unmask Brugada and long QT syndromes both were negative. Peak G400A and G400A+H558R current were 70.7% and 88.4% less than WT current at -35 mV (P </=.001). G400A current decay was accelerated and steady-state inactivation was shifted -6.39 mV (V(1/2) = -98.9 +/- 0.1 mV vs -92.5 +/- 0.1 mV, P </=.001). No mutations were detected in KCNH2, KCNQ1, KCNE1, or KCNE2 in the G400A patient.</AbstractText>We describe the first sodium channel mutation to be associated with the development of an arrhythmic storm during acute ischemia. These findings suggest that a loss of function in SCN5A may predispose to ischemia-induced arrhythmic storm.</AbstractText> |
8,461 | Spatially discordant voltage alternans cause wavebreaks in ventricular fibrillation. | Ventricular fibrillation (VF) is characterized by complex ECG patterns emanating from multiple, short-lived, reentrant electrical waves. The incessant breakup and creation of new daughter waves (wavebreaks) perpetuate VF. Dispersion of refractoriness (static or dynamic) has been implicated as a mechanism underlying wavebreaks.</AbstractText>The purpose of this study was to investigate the mechanisms underlying wavefront instability in VF by localizing wave fractionation sites (the appearance of multiple waves) and their relationship to local spatial dispersion of voltage (V(m)) oscillations.</AbstractText>Wave fractionations were identified by tracking V(m) oscillations optically at unprecedented spatial (100 x 100 pixels) and temporal (2,000 frames per second) resolution using a CMOS camera viewing the surface (1 x 1 cm(2)) of perfused guinea pig hearts (n = 6). VF was induced by burst stimulation, and wavefront dynamics were highlighted using region-based image analysis to automatically detect wavebreaks. Direct detection of wavebreak locations by image analysis was more reliable than the phase reconstruction method because baseline noise obstructed the correct identification of phase singularities by detecting false-positives.</AbstractText>Wave fractionations (34 +/- 4 splits/s.cm(2)) fell into three categories: decremental conduction (49% +/- 7%), wave collisions (32% +/- 8%), and wavebreaks (17 +/- 2%). Wavebreaks occurred at a frequency of 5.8 +/- 1 splits/s.cm(2) and did not preferentially occur at anatomic obstacles (i.e., coronary vessels) but coincided with discordant alternans where V(m) amplitudes and durations shifted from high to low to from low to high on opposite sides of wavebreak sites.</AbstractText>Spatial discordant alternans cause wavebreaks most likely because they are sites of abrupt dispersion of refractoriness.</AbstractText> |
8,462 | Atrial fibrillation is common after ablation of isolated atrial flutter during long-term follow-up. | Previous studies have shown that the incidence of atrial fibrillation after atrial flutter ablation is approximately 20% among patients presenting with typical atrial flutter and no history of fibrillation. However, studies involving this population have been small, with follow-up typically less than 2 years.</AbstractText>The purpose of this study was to provide a more accurate perspective on the long-term risk of atrial fibrillation in patients presenting with isolated typical flutter.</AbstractText>Clinical records of consecutive patients who had flutter ablations at Presbyterian Medical Center between 1999 and 2004 were assessed (n = 254). Patients with no apparent history of atrial fibrillation before their flutter ablation were identified. Retrospective follow-up data on these patients were obtained by review of medical records from our institution, from patients' cardiologists and primary care physicians, and by direct patient questionnaires. Postablation atrial fibrillation and other arrhythmias were identified by electrocardiography, Holter monitoring, and subsequent clinical records.</AbstractText>Postablation atrial fibrillation was identified in 40 (50%) of 80 patients, and an additional three patients presented with atypical atrial flutter, after a mean follow-up of 29.6 +/- 21.7 months. The incidence of atrial fibrillation was progressive, with 49% occurring after 2 years. There was no difference in age, left atrial size, hypertension, structural heart disease, or left ventricular dysfunction in patients who developed atrial fibrillation compared with those who did not.</AbstractText>Atrial fibrillation occurs in over half of patients who present with isolated typical flutter after cavotricuspid isthmus ablation. Asymptomatic patients should be screened for recurrent arrhythmias indefinitely after ablation. In certain patients, atrial fibrillation and flutter may be different expressions of the same electrical disease, and eradication of the flutter circuit will not prevent the eventual manifestation of atrial fibrillation.</AbstractText> |
8,463 | Prognostic significance of atrial fibrillation is a function of left ventricular ejection fraction. | Atrial fibrillation (AF) has been reported to be associated with decreased survival in population-based studies. Its prognostic importance in end-stage heart failure is not clear.</AbstractText>We investigated the prognostic implications of AF as function of left ventricular (LV) ejection fraction (EF) in 8,931 consecutive patients undergoing echocardiography at our medical center between 1990 and 1999. Patient characteristics were: age 66 +/- 13 years, EF 51 +/- 15, AF in 1,203 patients. There were 1,911 deaths over a mean follow up of 913 days. The prevalence of AF was 11% in patients with normal left ventricular ejection fraction (LVEF) (EF >/= 55%, n = 5, 130), and 18% each in those with mild (EF 41-54%, n = 1209), moderate (EF 26-40%, n = 1183) and severe reductions in left ventricular ejection fraction (LVEF) (EF </= 25%, n = 961). The 5-year survival rate was 72% for those in sinus rhythm compared to 56% for those in AF (p < 0.0001). The effect of AF on 5-year survival was most pronounced in those with normal LVEF (62 vs 78%, p < 0.0001) followed by those with mild reduction in LVEF (57 vs 72%, p = 0.02). It was not a predictor of survival in those with moderate (5-year survival 55 vs 61%, p = ns) or severe LV dysfunction (5-year survival 47 vs 45%, p = ns). Using the Cox regression model, AF was an independent predictor of mortality after correcting for age and LVEF in the entire cohort and in those with normal LVEF, but not in those with reduced LVEF. Among the other co-morbidities analyzed, an independent effect of AF on mortality was present in those with QTc >/= 450, raising a possibility of enhanced susceptibility of these patients.</AbstractText>The effect of AF on mortality diminishes with worsening LV function and is absent in those with severe LV dysfunction. Susceptibility of patients with QT prolongation to AF mortality warrants further attention.</AbstractText> |
8,464 | Treatment of ventricular dysrhythmias and sudden cardiac death: a guideline-based approach for patients with chronic left ventricular dysfunction. | With the rise in the use of device therapy implants, we are better identifying appropriate chronic heart failure patients for primary implantable defibrillator therapy who are at risk of ventricular arrhythmia. As our knowledge expands, however, controversial issues emerge. Guidelines have been endorsed by the major international societies, such as the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology. In view of certain variances in recommendations and new data, a recent joint guideline statement has been issued from these 3 societies regarding management of ventricular arrhythmia and preventing sudden cardiac death in patients with left ventricular dysfunction and heart failure. In this review, the recent joint statement is compared with those from the Heart Failure Society of America (Heart Failure Practice Guidelines 2006) and ACC/AHA (Heart Failure Guidelines 2005), with a special emphasis on new expanded criteria for primary prevention in both ischemic and nonischemic heart disease. In addition, the authors review current guidelines for electrophysiology testing in chronic left ventricular dysfunction and the emerging role of microvolt T-wave alternans as a means of risk stratification. |
8,465 | Optimal myocardial protection strategy for coronary artery bypass grafting without cardioplegia: prospective randomised trial. | Although hypothermia and ischaemic preconditioning (IP) are independently recognised mechanisms of cardioprotection, interactions between myocardial temperature and preconditioning have not been investigated. Therefore, this study explored the possibility of inducing IP during hypothermia and quantifying its effects at two temperature regimens commonly used in clinical practice. One hundred and four patients undergoing coronary artery bypass grafting (CABG) with intermittent cross-clamping and ventricular fibrillation were randomised to four groups: N=normothermia (36.5+/-0.5 degrees C); NP=normothermia+preconditioning, H=hypothermia (31.5+/-0.5 degrees C), HP=hypothermia+preconditioning. The primary outcome measure was release of cardiac Troponin I (cTnI), measured at 6 time points from pre- to 72 h after the end of CPB. There were no hospital deaths and no significant differences in pre- and intra-operative variables (P>or=0.05). There were significant differences in cTnI release between all groups, as follows: N: 117+/-12 microg/l (P<or=0.05 vs. all groups), NP: 87+/-8 microg/l (P<or=0.05 vs. groups N and HP), H: 76+/-6 microg/l (P<or=0.05 vs. groups N and HP), HP: 44+/-6 microg/l (P<or=0.05 vs. all groups). In conclusion, IP can be induced at both normothermia and moderate hypothermia, where it significantly reduces myocardial damage. Further studies are warranted to investigate the effects of the addition of hypothermia to pharmacological myocardial preconditioning. |
8,466 | Brain natriuretic peptide elevation and the development of atrial fibrillation following coronary artery bypass surgery. | The study was designed to determine whether the development of atrial fibrillation is associated with post-operative left ventricular dysfunction and subsequent left atrial stretch. We recruited 133 patients with well preserved pre-operative left ventricular function undergoing bypass surgery. Brain natriuretic peptide was measured at baseline, 24 and 48 h after the onset of cardiopulmonary bypass, and patients were monitored for 72 h after surgery. Atrial fibrillation occurred in 65 patients. Median 48 h brain natriuretic peptide levels were greater in the atrial fibrillation group (440 pg/ml (AF) and 319 pg/ml (non AF) P=0.001). As atrial fibrillation can cause an elevation in brain natriuretic peptide we divided the subjects into early atrial fibrillation (<48 h) and late (>48 h). In those with early atrial fibrillation there was no difference in the 24 h brain natriuretic peptide levels (381 pg/ml and 365 pg/ml P=0.73). In those with late atrial fibrillation the median 48 h brain natriuretic peptide level was greater than in the control group (405 pg/ml and 319 pg/ml, respectively, P=0.02). Brain natriuretic peptide levels rise significantly following bypass surgery. This increase was more evident in those who develop late atrial fibrillation which may suggest a role for atrial stretch in this arrhythmia. |
8,467 | Detection of atrial arrhythmia in superconducting quantum interference device magnetocardiography; preliminary result of a totally-noninvasive localization method for atrial current mapping. | Map-guided surgery is the goal for treatment of atrial fibrillation (AF), because it minimizes unnecessary incisions or procedures. We propose a totally-noninvasive and even non-contact method to detect atrial arrhythmia with a superconducting quantum interference device magnetocardiography (MCG) system, and report the first clinical application case of MCG map-guided AF surgery. To detect weak atrial excitation, we utilized a high sensitive 64-channel MCG system measuring tangential magnetic field components, which is known to be more sensitive to a deeper current source. We measured the MCG signals from eight patients with chronic AF. Then, we separated the f-wave from the other components by using independent component analysis. The extracted f-wave caused by reentrant myocardial excitation was three-dimensionally localized on the mesh model of a human heart by a novel beamformer technique having a surface action potential activity as its filter output. We localized the abnormal stimulation source of an atrial arrhythmia non-invasively and visualized the current source distribution corresponding to the atrial excitation successfully on the three-dimensional atrial surface, which was separated from the ventricular excitation. Using this atrial mapping, we underwent minimal AF surgery in three patients and converted their AF to sinus rhythm successfully. |
8,468 | Preoperative predictive factors for mortality in acute type A aortic dissection: an institutional report on 217 consecutives cases. | Surgical treatment of type A acute aortic dissection remains a challenge, especially in elderly patients or in patients with a critical preoperative status. We have retrospectively assessed our series over a 15-year period starting in 1990, including patients operated under cardiac massage for preoperative cardiac arrest occurring in the operating room. There were 217 patients (mean age, 61.5+/-13.5 years; 16 patients >80 years). Preoperative shock was noted in 21.7%, including 14 patients operated under cardiac massage. Operating procedures were: modified Bentall (31%), aortic tube (67.1%), other (1.9%), aortic arch procedure in 26.4%. Overall mortality rate was 19.8% with an exponential increase with age (50% over 80 years). Of 14 patients operated under cardiac massage, three have been discharged: one ventricular fibrillation due to an acute myocardial infarction and two among the 13 with acute aortic ruptures in cardiac arrest (one being a redo, the adhesions limiting the tamponade). Our results confirmed age and preoperative shock prior to surgery as risk factors, and the fact that operating on a patient under cardiac massage for cardiac arrest due to an aortic rupture is probably not a reasonable therapeutic choice. |
8,469 | The safety and efficacy of ibutilide in children and in patients with congenital heart disease. | The safety and efficacy of ibutilide in the cardioversion of atrial flutter and atrial fibrillation in children and in patients with congenital heart disease (CHD) is unknown.</AbstractText>Data from 19 patients (age 6 months to 34 years, median 16 years) who received ibutilide for atrial flutter or atrial fibrillation between 1996 and 2005 was retrospectively reviewed. There were 15 patients with CHD (14 had prior heart surgery); four children had normal heart structure.</AbstractText>There were 74 episodes of atrial flutter and four episodes of atrial fibrillation (median episodes per patient was one, range 1-31). Ibutilide converted 55 of all the episodes (71%). Ibutilide was successful during its first-ever administration in 12 of 19 patients (63%). Fourteen episodes in six patients required electrical cardioversion after ibutilide failed. There were no episodes of symptomatic bradycardia. One patient went into torsade de pointes and one patient had nonsustained ventricular tachycardia.</AbstractText>With careful monitoring, ibutilide can be an effective tool in selected patients for cardioversion of atrial flutter.</AbstractText> |
8,470 | Myocardial protection by erythropoietin during resuscitation from ventricular fibrillation. | Human recombinant erythropoietin (rhEPO) can protect the myocardium during ischemia and reperfusion. We investigated whether rhEPO could ameliorate previously identified functional myocardial abnormalities that develop during resuscitation from cardiac arrest, using a rat model of ventricular fibrillation (VF) and closed-chest resuscitation. VF was electrically induced and maintained, untreated, for 10 minutes. Chest compression and ventilation were then started and electrical defibrillation was attempted 8 minutes later. Rats were randomized to receive rhEPO (5000 U/kg) in the right atrium at baseline, 15 minutes before induction of VF (rhEPOBL -15-min), or at 10 minutes of VF, immediately before the start of chest compression (rhEPOVF 10-min), or to receive 0.9% NaCl solution instead (control). rhEPO given at the time of resuscitation (rhEPOVF 10-min group) -- but not at baseline -- prompted more effective chest compression, yielding higher coronary perfusion pressures for a given compression depth (1.95 +/- 0.27 mm Hg/mm; P < 0.05 in comparison with rhEPOBL -15-min [1.63 +/- 0.23 mm Hg/mm] and control [1.62 +/- 0.26 mm Hg/mm], by Dunnett's multicomparison method). Post-resuscitation, rats in the rhEPOVF 10-min group displayed higher mean aortic pressure associated with numerically higher cardiac index, stroke work index, and systemic vascular resistance index. rhEPO may rapidly induce myocardial protection during resuscitation from cardiac arrest. |
8,471 | The effect of vernakalant (RSD1235), an investigational antiarrhythmic agent, on atrial electrophysiology in humans. | To determine the acute effects of vernakalant (RSD1235) on electrophysiologic (EP) properties in humans.</AbstractText>Vernakalant is an investigational mixed ion channel blocker that can terminate acute atrial fibrillation (AF) in humans at 2 to 5 mg/kg and may be more "atrial-selective" than available agents.</AbstractText>Patients (N=19; 53% male; age, 48+/-11 years) underwent EP study before and after 25 minutes of intravenous vernakalant administration: 2 mg/kg over 10 min+0.5 mg/kg/hr for 35 min or 4 mg/kg over 10 min+1 mg/kg/hr for 35 min. EP measurements, including atrial refractory period (AERP) and ventricular refractory period (VERP), were obtained.</AbstractText>The lower dose prolonged AERP at 600, but not at 400 or 300 msec paced cycle length. The higher dose significantly prolonged AERP from 203+/-31 msec to 228+/-24 msec at 600 msec, 182+/-30 msec to 207+/-27 msec at 400 msec, and 172 msec+/-24 to 193+/-21 msec at 300 msec. There was no significant prolongation of VERP at either dose or at any cycle length. There was a small but significant prolongation of AV nodal refractoriness; Wenckebach cycle length prolonged by 18+/-12 msec (from baseline 343+/-54 msec) at the higher dose (P<0.05). Sinus node recovery time also increased by 123+/-158 msec (from baseline 928+/-237 msec) at the higher dose (P<0.05). There was a slight prolongation of QRS duration at the higher dose, during ventricular pacing at CL=400 msec (15+/-15 msec, P=0.0547). QT and HV intervals were unchanged.</AbstractText>At doses similar to those tested clinically, vernakalant dose-dependently prolonged atrial refractoriness, prolonged AV nodal conduction and refractoriness, and slightly prolonged QRS duration, but it had no effect on ventricular refractoriness.</AbstractText> |
8,472 | Effect of pacing the right ventricular mid-septum tract in patients with permanent atrial fibrillation and low ejection fraction. | Permanent right ventricular (RV) pacing leads have been traditionally implanted in the right ventricular apex (RVA). Nowadays, some deleterious effects of RVA pacing have been recognized. The aim of this study was to evaluate the effect of different sites of RV pacing in patients with permanent atrial fibrillation (AF) and low ejection fraction (LEF) needing a pacemaker (PM) implantation.</AbstractText>Two hundred seventy-three patients with permanent AF and EF <30% underwent a one-chamber rate responsive (VVIR) PM implant procedure. Patients were divided into two groups: Group A, including 113 patients with the pacing lead tip placed in the RV mid-septum, and Group B of 120 patients with the pacing lead tip placed at the apex of RV. All patients had clinical and Echo control after 1, 3, 6, 12, and 18 months after PM implantation to assess New York Heart Association (NYHA) class and EF.</AbstractText>After 18 months, NYHA class changed in Group A from 2.9 +/- 0.4 at implant to 1.7 +/- 0.3 at 18 months (P = 0.01), and in Group B from 3.0 +/- 0.5 at implant to 3.3 +/- 0.6 at 18 months (P = n.s.). EF increased in Group A: 28 +/- 2% at implant, 33 +/- 1% at 18 months (P = 0.0125), while no significant changes were observed in Group B: at implant 27 +/- 2%, 26 +/- 2% at 18 months (P = n.s.).</AbstractText>The present study suggests that more physiological pacing from the RV sept can improve EF and quality of life (QoL) in patients with permanent AF and low EF needing a PM.</AbstractText> |
8,473 | Prevalence of paroxysmal atrial fibrillation depending on the regression of left ventricular hypertrophy in arterial hypertension. | Arterial hypertension (HTN) represents one of the major causes of atrial fibrillation, a cardiac arrhythmia with high prevalence and comorbidity. The aim of this study was to investigate whether paroxysmal atrial fibrillation can be treated by the regression of left ventricular hypertrophy achieved by antihypertensive therapy. Included in the present study were 104 patients who had had HTN for more than 1 year. None of them suffered from coronary heart disease. All patients were investigated by 24-h Holter ECG and echocardiography at baseline and after a mean of 24 months. Patients were divided into two groups: group A consisted of those (53.8%) who showed a regression of the left ventricular muscle mass index (LVMMI) during the follow-up (154.9+/-5.1 vs. 123.5+/-2.8 g/m(2)), and group B those (45.2%) who showed a progression of LVMMI (122.2+/-3.2 vs. 143.2+/-3.2 g/m(2)). In group A the prevalence of atrial fibrillation decreased from 12.5% to 1.8% (p<0.05), while it was increased in group B from 8.5% to 17.0%. The left atrial diameter was reduced following antihypertensive therapy in group A from 39.1+/-5.3 mm to 37.4+/-4.6 mm (p<0.01) and increased in group B from 37.0+/-0.7 mm to 39.0+/-0.9 mm (p<0.01). We conclude that a regression of the left ventricular muscle mass leads to a reduction of left atrial diameter and consecutively to a decrease in the prevalence of intermittent atrial fibrillation. This may be explained by a better left ventricular diastolic function following decreased vascular and extravascular resistance of the coronary arteries. This relation shows the benefits of causal antihypertensive therapy for the treatment of paroxysmal atrial fibrillation. |
8,474 | Comparative study of methods for ventricular activity cancellation in atrial electrograms of atrial fibrillation. | Atrial fibrillation is a very common cardiovascular disease in clinical practice. One relevant issue to understand its pathophysiological mechanisms is the analysis and interpretation of atrial electrograms (AEG). To study these signals properly, ventricular activity has to be removed from the AEG. In this work, a new application of independent component analysis (ICA) to the AEG is presented, where ventricular activity is removed from atrial epicardial recordings making use of only one reference lead. Therefore the technique is suitable when multi-lead recordings are unavailable as in atrial implantable cardioverter defibrilators. In addition to the proposed new methodology this work also presents the first comparative study, making use of unipolar epicardial AEGs, among the ICA-based technique, template matching and subtraction (TMS), and adaptive ventricular cancellation (AVC) on a database of 20 patients. A performance comparative analysis was carried out by evaluating epicardial atrial waveform similarity (S) and ventricular depolarization reduction (VDR) as a function of atrial rhythm regularity on a beat-by-beat basis. Results indicate that, when the epicardial atrial rhythm is quite organized, ICA is able to preserve the atrial waveform very precisely and better than the other methods (median S = 99.64% +/- 0.31% in contrast to 95.18% +/- 2.71% for TMS and 94.76% +/- 4.12% for AVC). Moreover, ventricular reduction is the best for ICA (median VDR = 6.32 +/- 4.41 dB in contrast to 4.98 +/- 4.48 dB for TMS and 4.12 +/- 2.72 dB for AVC). On the other hand, when the atrial activity is disorganized, TMS notably improves performance (S = 97.72% +/- 1.87%), but ICA still is the best in waveform preservation (S = 98.22% +/- 1.53%) whereas AVC remains similar (S = 93.74% +/- 4.38%). In conclusion, ICA can be considered as notably the best approach to reduce ventricular activity from unipolar atrial electrograms in organized atrial arrhythmias. On the other hand, both TMS and ICA give quite similar results when the atrial arrhythmia is disorganized. |
8,475 | Comparison of optical and electrical mapping of fibrillation. | Optical recordings with transmembrane potential (Vm)-sensitive fluorescent dye, or extracellular potential (Ve) recordings are used to map spatiotemporal patterns of cardiac excitation during ventricular fibrillation (VF). While the optical and electrical methods are accepted, there has not been a test of whether they yield equivalent excitation times during VF. Times may differ since previous results indicate optical Vm interrogates deeper than Ve. We tested whether the steepest parts of the downward deflection of the Ve and upward deflection of optical Vm are synchronized during VF. We used simultaneous coepicentral optical and electrical mapping (32 spots, 4 kHz) with translucent indium tin oxide electrodes and a laser scanner on ventricular epicardium. VF was electrically induced in arterially-perfused rabbit hearts stained with di-4-ANEPPS. For both the optical and electrical deflections, maximum magnitudes of the slopes varied over a > 4 fold range, morphologies varied and spatiotemporal distributions were nonuniform. Time differences between the steepest parts of the optical and electrical deflections were typically a few ms. Standard deviations of time differences increased for the deflections that had the smaller slopes, which was only partly due to effects of recording noise as indicated by simulations. For deflections that had slopes ranging from the steepest found at each spot to 1/4 of the steepest, the optical deflections were on average 0.7-1 ms earlier than the Ve deflections. Thus, excitation times during VF measured optically and electrically differ. Considered together with our earlier results indicating that the optical Vm interrogates deeper than Ve, the results suggest that most fibrillatory excitations occur earlier in subsurface tissue than at the heart surface. |
8,476 | Regression of electrocardiographic left ventricular hypertrophy during antihypertensive therapy and reduction in sudden cardiac death: the LIFE Study. | Sudden cardiac death (SCD) occurs more often in patients with ECG left ventricular (LV) hypertrophy. However, whether LV hypertrophy regression is associated with a reduced risk of SCD remains unclear.</AbstractText>The Losartan Intervention for End Point Reduction in Hypertension (LIFE) study included 9193 patients 55 to 80 years of age with essential hypertension and ECG LV hypertrophy by gender-adjusted Cornell product (CP) (RaVL+SV(3) [+6 mm in women]). QRS duration>2440 mm x ms) and/or Sokolow-Lyon voltage (SLV) (SV1+RV(5/6)>38 mm). During follow-up (mean, 4.8 years), 190 patients (2%) experienced SCD. In time-dependent Cox analyses, absence of in-treatment LV hypertrophy was associated with a decreased risk of SCD: every 1-SD-lower in-treatment CP (1050 mm x ms) was associated with a 28% lower risk of SCD (hazard ratio [HR], 0.72; 95% CI, 0.66 to 0.79) and 1-SD-lower SLV (10.5 mm) with a 26% lower risk (HR, 0.74; 95% CI, 0.65 to 0.84). After adjustment for time-varying systolic and diastolic blood pressures, treatment allocation, age, gender, baseline Framingham risk score, ECG strain, heart rate, urine albumin/creatinine ratio, smoking, diabetes, congestive heart failure, coronary heart disease, atrial fibrillation, and occurrence of myocardial infarction, atrial fibrillation, heart failure, and noncardiovascular death, both in-treatment CP and SLV remained predictive of SCD: each 1-SD-lower CP was associated with a 19% lower risk of SCD (HR, 0.81; 95% CI, 0.73 to 0.90) and 1-SD-lower SLV with an 18% lower risk (HR, 0.82; 95% CI, 0.70 to 0.98). Absence of in-treatment LV hypertrophy by both SLV and CP was associated with a 30% lower risk of SCD (HR, 0.70; 95% CI, 0.54 to 0.92).</AbstractText>Absence of in-treatment ECG LV hypertrophy is associated with reduced risk of SCD independently of treatment modality, blood pressure reduction, prevalent coronary heart disease, and other cardiovascular risk factors in hypertensive patients with LV hypertrophy.</AbstractText> |
8,477 | Repolarization characteristics and incidence of Torsades de Pointes in patients with acquired complete atrioventricular block. | Torsades de pointes (TdP) during bradyarrhythmias have been reported to be associated with gender, degree of QT prolongation and duration of bradyarrhythmia. We sought to investigate the repolarization characteristics on 12-lead electrocardiogram (ECG) and the incidence of TdP in patients with acquired complete atrioventricular block (CAVB).</AbstractText>Fifty consecutive patients with acquired CAVB were included in the study. Patients with coronary artery disease, systolic dysfunction and previous cardiac surgery were excluded. Patients were monitored during hospitalization for ventricular arrhythmias (VA). Serum potassium, magnesium, calcium levels and thyroid-stimulating hormone were measured. Heart rate, QRS duration, QT/QTc, JT/JTc and Tpeak-Tend intervals were measured. Pathologic U waves, T-U complex, and QT morphologies were remarked.</AbstractText>Patients presented with presyncope (n=39, 78%), syncope (n=12, 24%), and palpitations (n=8, 16%). All patients were in sinus rhythm. Duration of CAVB was 8.5 days (median). Patients were divided into two groups based on JT interval. Group 1 (JT=or>500 ms, n=13) tended to have more female patients and more VAs in comparison to Group 2 (JT<500 ms, n=37). Group 1 patients had more pathologic U waves and T-U complexes, longer Tpeak-Tend intervals, and more long QT2 syndrome (LQT2)-like QT morphology in comparison to Group 2 patients. Group 2 patients had more often syncope. One patient in Group 2 developed ventricular fibrillation in the presence of hypokalemia and hypomagnesemia.</AbstractText>Torsades de Pointes during CAVB was rare among our patient population. The predictors of VA during CAVB were presence of prolonged QTc/JTc intervals, pathologic U wave and T-U complex, prolonged Tpeak-Tend interval, and LQT2-like QT morphology.</AbstractText> |
8,478 | Changes in ionic currents and reduced conduction velocity in hypertrophied ventricular myocardium of Xin alpha-deficient mice. | mXin alpha, a downstream target gene of Nkx2.5 transcription factor, was shown to encode a proline-rich and Xin repeats-containing protein which localizes to the intercalated disc of adult hearts. Our previous voltage-clamp studies have shown that the ventricular myocytes of mXin alpha -deficient mice exhibited a significant reduction in K+ currents (Ito and IK1), L-type Ca2+ currents, and maximum diastolic potential, leading to the development of early afterdepolarization (EAD) and arrhythmias. However, changes in cationic inward currents could also contribute to the genesis of EAD and arrhythmias in mXin alpha -deficient mice.</AbstractText>The present study aims to characterize changes in Na+ currents on depolarization and transient inward currents (Iti) on repolarization. Conduction velocity (CV) on the frontal surface of ventricles were also measured and compared.</AbstractText>Results of optical mapping on the Langendorff-perfused hearts at 37oC revealed a 36% reduction of CV in mXin alpha -/- ventricle. Pacing (3 Hz)-induced tachyarrhythmias were more frequently found and ventricular fibrillation (VF, 21 Hz for 5 min) occurred in one out of 8 mXin alpha-/- heart. When perfused at 30 degrees C, no VF was observed in both types of preparations. Voltage-clamp study on isolated ventricular myocytes at 37 degrees C shows increase in INa and Iti in mXin alpha -/- cardiomyocytes thus could explain the occurrence of re-entrant triggered arrhythmias.</AbstractText>The present results revealed that the CV was slower, but INa and Iti were increased in mXin alpha -/-cardiomyocytes thus were prone to reentrant triggered arrhythmias. Hypothermia could reduce the occurrence of arrhythmias.</AbstractText> |
8,479 | Clinical impact of surface electrocardiography of cardiac arrhythmias in pacemaker-ICD patients. | Cardiologists often are called to explain electrocardiograms of pacemaker/ implantable cardioverter (PMK/ICD) patients during arrhythmic events. The most frequent arrhythmia is atrial fibrillation (AF) whether in PMK or in ICD patients. Generally, it is not difficult to diagnose, it can affect the quality of life of this subgroup because it can generate inappropriate and painful therapies. Arrhythmias as atrioventricular block or other bradyarrhythmias can show a particular way of presentation specially for the device's intervention using specific algorithms that cardiologists should know to adequately interpret the phenomenon. For example, Rate Drop Response algorithm (to prevent syncope) or other antiarrhythmic functions for atrial tachyarrhythmias (Post Mode Switching Overdrive Pacing (PMOP) or Atrial Rate Stabilization) can alter surface electrocardiogram after AF or atrial ectopic beats. Ventricular arrhythmias in ICD patients are frequent. Burst, ramp and shock are therapies with a high percentage of efficacy. However, sometimes, supraventricular arrhythmias (SVT) can induce inappropriate interventions. In other cases appropriate burst, ramp or shock (during a ventricular tachycardia (VT)) can degenerate it in a fast ventricular tachycardia or in ventricular fibrillation with consequent shocks. Wavelet, onset, stability, and other algorithms, specifically in dual chamber ICDs, are used to discriminate SVT from VT assuring more specific interventions. |
8,480 | Magnetocardiography provides non-invasive three-dimensional electroanatomical imaging of cardiac electrophysiology. | More than two decades of research work have shown that magnetocardiographic mapping (MCG) is reliable for non-invasive three-dimensional electroanatomical imaging (3D-EAI) of arrhythmogenic substrates. Magnetocardiographic mapping is now become appealing to interventional electrophysiologists after recent evidence that MCG-based dynamic imaging of atrial arrhythmias could be useful to classify patients with atrial fibrillation (AF) before ablation and to plan the most appropriate therapeutic approach. This article will review some key-points of 3D-EAI and discuss what is still missing to favor clinical applicability of MCG-based 3D-EAI.</AbstractText>Magnetocardiographic mapping is performed with a 36-channel unshielded mapping system, based on DC-SQUID sensors coupled to second-order axial gradiometers (pick-up coil 19 mm and 55-70 mm baselines; sensitivity of 20 fT/Sqrt[Hz] in above 1 Hz), as part of the electrophysiologic investigation protocol, tailored to the diagnostic need of each arrhythmic patient. More than 500 arrhythmic patients have been investigated so far.</AbstractText>The MCG-based 3D-EAI has proven useful to localize well-confined arrhythmogenic substrates, such as focal ventricular tachycardia or preexcitation, to understand some causes for ablation failure, to study atrial electrophysiology including spectral analysis and localization of dominant frequency components of AF. However, MCG is still missing software tools for automatic and/or interactive 3D imaging, and multimodal data fusion equivalent to those provided with systems for invasive 3D electroanatomical mapping.</AbstractText>Since there is an increasing trend to favor interventional treatment of arrhythmias, clinical application of MCG 3D-EAI is foreseen to improve preoperative selection of patients, to plan the appropriate interventional approach and to reduce ablation failure.</AbstractText> |
8,481 | Importance of body surface potential field representation fidelity: analysis of beat-to-beat repolarization measurements. | According to previous studies, the complex substrate of malignant arrhythmias needs a detailed spatio-temporal noninvasive characterization of low-amplitude dynamic changes in beat-to-beat cardiac repolarization.</AbstractText>Body surface potential map (BSPM) records were taken on 14 healthy male and female subjects (age 20-80 years) and on 6 ventricular arrhythmia patients, 4 of them with implanted cardioverter defibrillators (ICD). Records were taken continuously, for 5 minutes, in resting, supine position. Beat-to-beat QRST integral maps, Karhunen-Loéve coefficient time-series (KLi, i=1-12), RR and nondipolarity index (NDI) time-series were computed.</AbstractText>The first order statistical properties of the spatio-temporal variability of subsequent QRST integral maps were characterized by the box and whiskers plot of their KLi components. The SD2/M2 (KLi amplitude variance/mean signal energy) values of the QRST integral maps in the normal group ranged between 0.0057 and 0.008 (i.e. 0.075=or<SD/M=or<0.089). In ICD patients SD2/M2 values went up to 0.021-0.069 (i.e: 0.14=or<SD/M=or<0.26). Autocorrelation functions revealed that while in normal subjects only 5-20% of the total power had white noise character, the rest was bandwidth-limited noise. In ICD patients the weight of white noise component increased considerably. The higher the SD/M relative KL variability, the higher and more frequent NDI spikes were.</AbstractText>Beat-to-beat dynamics of white noise components of high resolution BSPMs are able to stratify arrhythmia vulnerability. The temporal distribution of extreme NDI spike formations is random; the frequency is associated with the relative KL component noise levels.</AbstractText> |
8,482 | Enhanced heterogeneity of myocardial conduction and severe cardiac electrical instability in annexin A7-deficient mice. | Annexin A7 is involved in cardiomyocyte membrane organization and Ca(2+)-dependent signalling processes. We investigated the impact of annexin A7 on cardiac electrophysiological properties using an annexin A7-deficient mouse strain (annexin A7(-/-)).</AbstractText>Nineteen adult annexin A7(-/-) and 14 wild-type mice were examined electrophysiologically in vivo by transvenous catheterization. Hearts were additionally perfused by the Langendorff method and epicardial activation mapping was performed.</AbstractText>The susceptibility to induction of atrial fibrillation was elevated in annexin A7(-/-) mice. Ten deficient animals showed atrial fibrillation (AF) episodes > or =1 min and sustained AF > or =30 min was observed in 4 annexin A7(-/-) mice, but in none of the wild-type mice. The incidence of ventricular tachycardia (VT) was higher in annexin A7(-/-) mice and VT duration was prolonged. Epicardial mapping showed elevated anisotropy and inhomogeneity of conduction, leading to conduction blocks in the deficient mice. Besides alterations of intracellular calcium homeostasis, electron microscopy showed a homogeneous, electron-dense material that filled the myocardial intercellular compartments and accumulated at the basement membranes. This led to expansion of the extracellular spaces, which was the most probable substrate factor responsible for the disturbances of electrical communication.</AbstractText>Annexin A7 deficiency causes severe electrical instability in the murine heart, including conduction disturbances and anisotropy of impulse propagation, which is accompanied by disturbed calcium handling and intercellular deposits.</AbstractText> |
8,483 | Hemangioma located just above the left main coronary artery, in a subject who had cardiac arrest due to ventricular fibrillation, led to a diagnosis of Brugada syndrome. | We report the case of a 38-year-old Asian man with a pericardial hemangioma on the left main coronary artery. The patient presented initially at our hospital after cardiopulmonary resuscitation following an episode of ventricular fibrillation (VF). Because of spontaneous coved-type ST segment elevation on the higher intercostal space V1 to V2 in a 12-lead electrocardiogram, documented VF in the absence of structural heart disease, and a family history of sudden death, he was diagnosed with Brugada syndrome. Transesophageal echocardiography showed a smooth-surfaced mass with well-demarcated borders, directly above the left main coronary artery. Computed tomography confirmed the presence of the mass, which showed no enhancement at early phase, but did demonstrate homogenous enhancement at delay phase by contrast material. There were no findings from either the nuclear medicine or the tumor marker investigations which indicated that the mass located just above the main coronary arteries was malignant. Therefore, taken together, these findings suggested that the tumor might be a pericardial hemangioma. The relationship between the location of the hemangioma just above the left main coronary artery and the occurrence of VF was not clear, i.e. whether the presence of the hemangioma caused the stimulation of the left main coronary artery and as a result, led to the spasm of the left main coronary artery and the occurrence of VF. Furthermore, as the tumor did not extend into any of the adjacent structures, such as the coronary arteries or the right ventricular outflow tract, surgical resection was not performed; instead, the patient received a dual chamber implantable cardioverter-defibrillator. |
8,484 | [Clinical characteristics of patients diagnosed of chronic heart failure attended in Primary Care. The CARDIOPRES study]. | Scarce information is available on the clinical characteristics and risk factors of patients with chronic heart failure (CHF) attended in Primary Care (PC) setting. The aim of this study was to analyze the clinical characteristics of this population in PC.</AbstractText>Multicenter, cross-sectional study in patients with CHF, consecutively recruited by 232 physicians in PC. The collected data included sociodemographic, etiologic, clinical and therapeutic variables.</AbstractText>Eight hundred forty seven (847) patients were included (age 73.0 +/- 9.6 years; 50.5% men). Of these, 84.3% had arterial hypertension (AHT), 59.2% hypercholesterolemia and 34.9% diabetes mellitus. The most frequent associated clinical disorders were ischemic heart disease (40.1%) and peripheral artery disease (28.6%). In 69.6% of the patients the physicians knew the type of dysfunction (32.4% systolic, 37.2% diastolic). The main etiologies of CHF were the hypertensive cardiomyopathy (75.0%) and ischemic heart disease (40.1%); the most frequent trigger factor was atrial fibrillation (43.9%). Loop diuretics (72.3%) and angiotensin-converting enzyme inhibitors (60.9%) were the treatments used most and 6.7% of the patients were receiving treatment with beta blockers.</AbstractText>AHT appears to be primary cause of CHF in PC. Diastolic dysfunction is more frequent than the systolic one, and the PC physicians do not know the cause of the ventricular dysfunction in one third of the cases. Loop diuretics and angiotensin-converting enzyme inhibitors were the most frequently used in these patients; the use of beta blockers in CHF is very scarce in PC.</AbstractText> |
8,485 | Circadian rhythms in cardiac arrhythmias and opportunities for their chronotherapy. | It is now well established that nearly all functions of the body, including those that influence the pharmacokinetics and pharmacodynamics of medications, exhibit significant 24-hour variation. The electrical properties of the heart as well as cardiac arrhythmias also vary as circadian rhythms, even though the suboptimal methods initially used for their investigation slowed their identification and thorough characterization. The application of continuous Holter monitoring of the electrical properties of the heart has revealed 24-hour variation in the occurrence of ventricular premature beats with the peak in events, in diurnally active persons, between 6 a.m. and noon. After the introduction of implantable cardioverter-defibrillators, ventricular tachycardia or fibrillation were also found to peak in the same period of the day. Even defibrillator energy requirements show circadian variation, thus supporting the need for a temporal awareness in the therapeutic approach to arrhythmias. Imbalanced autonomic tone, circulating levels of catecholamines, increased heart rate and blood pressure, all established determinants of cardiac arrhythmias, show circadian variations and underlie the genesis of the circadian pattern of cardiac arrhythmias. Arrhythmogenesis appears to be suppressed during nighttime sleep, and this can influence the evaluation of the efficacy of antiarrhythmic medications in relation to their administration time. Unfortunately, very few studies have been undertaken to assess the proper timing (chronotherapy) of antiarrhythmic medications as means to maximize efficacy and possibly reduce side effects. Further research in this field is warranted and could bring new insight and clinical advantage. |
8,486 | Predictors of mortality after aortic valve replacement. | Aortic valve replacement (AVR) is recommended as a standard surgical procedure for aortic valve disease. Still the evidence for commonly claimed predictors of post-AVR prognosis, in particular mortality, appears scant. This systematic review reports on the evidence for predictors of post-AVR mortality, and may be helpful in pre-surgical risk-stratification. In PubMed, we searched for original reports of post-AVR follow-up studies. We assessed the quality of study design and methods with a standardized checklist. Data of the reported predictors of mortality and outcomes were extracted. Twenty-eight studies met our inclusion criteria. Sixteen studies were considered of high quality. There is strong evidence that the risk of early mortality is increased by emergency surgery, while the risk of late mortality is increased with older age and preoperative atrial fibrillation. There is moderate evidence that the risk of early mortality is increased by older age, aortic insufficiency, coronary artery disease, longer cardiopulmonary bypass time, reduced left ventricular ejection fraction (LV-EF), infective endocarditis, hypertension, mechanical valves, preoperative pacing, dialysis-dependent renal failure and valve size; and that the risk for late mortality is increased by emergency surgery and urgency of the operation. There is little evidence for high New York Heart Association class, concomitant coronary artery bypass graft and many other commonly claimed risk factors for post-AVR mortality. The reported evidence on predictors of post-AVR mortality will help for pre-surgical risk-stratification, i.e. to discern patients at high or low risk for early and late post-AVR mortality. Future prognostic studies should take the evidence from this review into account and should focus on derivation of a predictive model for post-AVR survival. |
8,487 | Increased prevalence of ventricular fibrillation in patients with type 2 diabetes mellitus. | Diabetes mellitus (DM) is an independent risk for cardiovascular disease. Furthermore, patients with DM have increased risk for ventricular arrhythmia that is thought to be secondary to coronary artery disease (CAD) or congestive heart failure (CHF). We hypothesized that DM may cause ventricular arrhythmias independent of CAD or CHF. Using a large database, we evaluated the occurrence of ventricular fibrillation in patients with DM adjusting for CAD and CHF. We used patient treatment files (PTF), documents of inpatients' admissions containing discharge diagnoses (ICD-9 codes) from all Veterans Health Administration Hospitals. The patients were stratified in two groups: ICD-9 code for DM (293 124) and a control group with ICD-code for hypertension (HTN) but no DM (552 623). ICD-9 codes for ventricular fibrillation were used for this study. We performed uni- and multivariant analysis adjusting for comorbid conditions. Ventricular fibrillation was present in 563 (0.2%) vs 781 (0.1%) in the control group. Using multivariate analysis, DM remained independently associated with ventricular fibrillation (odds ratio: 1.7; confidence interval: 1.5-1.9; P < 0.000). Patients with DM have significantly higher prevalence of ventricular fibrillation independent of CAD or CHF, which in part may explain the higher risk of sudden death in patients with DM. |
8,488 | Comparative study of intravenous amiodarone and procainamide in the treatment of atrial fibrillation of recent onset. | The aim of the present study was to compare the safety and efficacy of amiodarone and procainamide in the acute cardiology setting.</AbstractText>The study population consisted of 223 patients with symptomatic atrial fibrillation (AF). After administration of digoxin for ventricular rate control, all patients who failed to restore sinus rhythm (SR) were randomized into 2 groups: group A (113 patients) were administered 300 mg amiodarone intravenously over 30 min and, in case of failure to restore SR, amiodarone of 20 mg/kg/24 h was administered intravenously. Group B (110 patients) were intravenously administered a bolus dose of 1 gm procainamide, at an infusion rate 50/mg/min, and, in case of failure to restore SR, 2 mg/min for the next 24 h.</AbstractText>The rate of cardioversion to SR was similar between amiodarone (81.4%) and procainamide (82.7%) (P=NS). Procainamide loading recorded faster cardioversion times than amiodarone loading (P=0.02), but there was no significant difference after that. Amiodarone caused a significant decrease on systolic blood pressure compared to procainamide for the first 18 h (P<0.001), and a significant decrease in the diastolic blood pressure for the first 6 h (P<0.001). Side-effects for either medication were sparse. The only real prognostic factor for successful cardioversion remains the size of left atrium.</AbstractText>Both drugs were equally effective in restoring SR, though procainamide acts quicker in the loading phase. Both medications are safe and side effects develop only in the maintenance phase.</AbstractText> |
8,489 | Endocardial electrograms from the right ventricular outflow tract after induced ventricular fibrillation in patients with Brugada syndrome. | The pathogenesis of Brugada syndrome (BS) is reported to be phase 2 reentry resulting from shortening of the action potential duration at the epicardial site of the right ventricular outflow tract (RVOT). However, several reports have shown a high incidence of ventricular late potentials (LPs) and a high rate of induction of ventricular fibrillation (VF) by programmed ventricular stimulation (PVS) among patients with BS. The aim of this study was to investigate the role of slow conduction for the initiation of VF by PVS in these patients.</AbstractText>Endocardial mapping of the RVOT was conducted in 17 patients in whom VF was induced by PVS from the RV apex or RVOT; 11 patients had a positive LP. In 10 patients, RV mapping showed that low-amplitude fragmented and delayed potentials (DPs) were recorded at the RVOT below the pulmonary valve (PV) or between the PV and His bundle electrogram recording site. Electrograms recorded after PVS showed a high incidence of fractionated and disorganized DPs that lead to VF.</AbstractText>Slow conduction at the RVOT may contribute to the induction of VF by PVS. However, the role of slow conduction in spontaneous VF remains controversial.</AbstractText> |
8,490 | Endothelin receptor antagonist CPU0213 suppresses ventricular fibrillation in L-thyroxin induced cardiomyopathy. | Arrhythmias correlate with disorders of either K(2+) channels in sarcolemma or calcium modulating system in sarcoplasmic reticulum which handles Ca(2+) intracellularly. We hypothesized that an activated endothelin (ET) signaling pathway, which may be associated with an alteration of K(+) channels and Ca(2+) uptake activity in the myocardium, participated in the exaggerated ventricular fibrillation (VF) incidence in cardiomyopathy (CM) induced by L-thyroxin. We intended to test if a dual endothelin receptor antagonist CPU0213 is effective to suppress VF correlating with a reversal of abnormalities in expression of the ion channels in sarcolemma and sarcoplasmic reticulum. The CM was induced by L-thyroxin administration for 10 days, and the altered expression of ion channels and the ET system was examined and the susceptibility to VF was evaluated by 10-min ischemia followed by reperfusion (I/R). Rats were treated with either propranolol or CPU0213 from day 6-10 of L-thyroxin medication. An increased VF incidence on I/R episode in the CMwas found relative to control. An elevated myocardial ET-1 and preproET-1 expression were associated with abnormal mRNAlevel of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a), phospholamban (PLB), and ERG, MinK, and Kv4.2 in sarcolemma. Propranolol and CPU0213 were equally effective in reversing the alterations of gene phenotype and exaggerated VF in CM hearts. In conclusion, an activated ET receptor signaling plays a role in the progression of augmented VF in association with abnormal expression of ion channels in both sarcolemma and sarcoplasmic reticulum in the CM. |
8,491 | Nandrolone potentiates arrhythmogenic effects of cardiac ischemia in the rat. | Anabolic steroid abuse has been associated with thrombosis and arteriosclerosis, both of which predispose to myocardial ischemia and infarction. However, there are reports of sudden cardiac death in the absence of thrombus and atheroma following anabolic steroid use. Although treatment with the commonly abused steroid, nandrolone, has been shown to decrease recovery of systolic function following ischemia in isolated rat hearts, it is unknown whether anabolic steroids can increase the incidence of fatal arrhythmia associated with cardiac ischemia. Anesthetized male Sprague-Dawley rats were administered vehicle or nandrolone (10-160 microg/kg/min iv) 10 min prior to 15-min occlusion of the left anterior descending coronary artery followed by 10-min reperfusion. Nandrolone, in this dose range, did not significantly change heart rate, blood pressure, or cardiac rhythm in the absence of ischemia. However, the fraction of rats surviving ischemia was significantly (p < 0.05) decreased by nandrolone at both 40 and 160 microg/kg/min, while survival time during ischemia was decreased significantly (p < 0.001) by nandrolone 160 microg/kg/min. An increase (p < 0.05) in the duration of ventricular fibrillation was noted at the highest compared to the lowest dose of nandrolone, corresponding to a significant increase in the fraction of rats experiencing ventricular fibrillation (p < 0.01). Nandrolone had no effect on the frequency or duration of ventricular fibrillation or survival time during reperfusion. Although the mechanisms underlying these effects are currently unclear, they indicate that exposure to anabolic steroids in combination with transient reductions in coronary blood flow may explain some reports of sudden cardiac death in anabolic steroid users. |
8,492 | Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy. | Recently, the implantable cardioverter-defibrillator (ICD) has been promoted for prevention of sudden death in hypertrophic cardiomyopathy (HCM). However, the effectiveness and appropriate selection of patients for this therapy is incompletely resolved.</AbstractText>To study the relationship between clinical risk profile and incidence and efficacy of ICD intervention in HCM.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PATIENTS" NlmCategory="METHODS">Multicenter registry study of ICDs implanted between 1986 and 2003 in 506 unrelated patients with HCM. Patients were judged to be at high risk for sudden death; had received ICDs; underwent evaluation at 42 referral and nonreferral institutions in the United States, Europe, and Australia; and had a mean follow-up of 3.7 (SD, 2.8) years. Measured risk factors for sudden death included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope.</AbstractText>Appropriate ICD intervention terminating ventricular tachycardia or fibrillation.</AbstractText>The 506 patients were predominately young (mean age, 42 [SD, 17] years) at implantation, and most (439 [87%]) had no or only mildly limiting symptoms. ICD interventions appropriately terminated ventricular tachycardia/fibrillation in 103 patients (20%). Intervention rates were 10.6% per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39% [SD, 5%]), and 3.6% per year for primary prevention (5-year probability, 17% [SD, 2%]). Time to first appropriate discharge was up to 10 years, with a 27% (SD, 7%) probability 5 years or more after implantation. For primary prevention, 18 of the 51 patients with appropriate ICD interventions (35%) had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers (3.83, 2.65, and 4.82 per 100 person-years, respectively; P = .77). The single sudden death due to an arrhythmia (in the absence of advanced heart failure) resulted from ICD malfunction. ICD complications included inappropriate shocks in 136 patients (27%).</AbstractText>In a high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients who had undergone implantation for a single risk factor. Therefore, a single marker of high risk for sudden death may be sufficient to justify consideration for prophylactic defibrillator implantation in selected patients with HCM.</AbstractText> |
8,493 | [Surgical ablation therapy - lessons learned]. | Atrial fibrillation (AF) is the most frequent sustained arrhythmia affecting more than 5% of the population above 65 years resulting in loss in quality of life and life expectancy. Since the introduction of the MAZE procedure, an increasing number of surgical approaches have been implemented for the treatment of AF. During past years a variety of devices such as application of unipolar and bipolar radiofrequency, cryothermal therapy, microwave, laser and ultrasound have been described. All new methods have undergone thorough evaluations; in that course technical systems have been re-designed and surgical approaches were modified. Before reaching a widespread clinical application a thorough analysis in terms of therapeutic benefit and possible complications is required. Several reports have reported success rates leading to reinstitution of atrial rhythm in 60 to 80% of the patients treated. However, there is no overview on possible complications using surgical ablation therapy. In this report we have focused on different energy sources, time of occurrence of postoperative arrhythmias, patient's symptoms and related diagnostic processes. Various published reports of surgical ablation therapy were evaluated with regard to complications that have occurred. In addition, our own extensive experience was considered as well. |
8,494 | Surgical treatment of atrial fibrillation : a systematic review. | The recently published overwhelming number of publications on the surgical treatment of AF, using a wide variety of techniques, blurred any precise appreciation of the nowadays surgical treatment of AF. As a consequence, the "state of the art" of the surgical technique of AF is ill-defined.</AbstractText>In this review the efficacy of the alternative sources of energy (radiofrequency-microwave and cryoablation; (group I) and the classical "cut and sew" Cox-Maze III (group II), which claims a 97-99% sinus rhythm (SR) success rate, were evaluated in the surgical treatment of atrial fibrillation (AF).</AbstractText>A computerized search in the PubMed and Medline database was conducted. Only original, English written, clinical manuscripts on the surgical treatment of atrial fibrillation citing the clinical outcome, including the postoperative sinus rhythm, were included. The following data were registered: the absolute numbers and percentages of treated patients, gender (male versus female) distribution, the type of arrhythmia (permanent or paroxysmal AF), type of surgery (mitral or non-mitral valve or a lone AF surgical procedure), postoperative morbidity (bleeding, the use of an intra-aortic balloon pump, cerebral vascular accident), postoperative pacemaker implantations, 30-day mortality, survival and sinus rhythm conversion. The mean values for age (years), left atrial diameter (mm), preoperative duration of AF (years) and left ventricular ejection fraction (%) were also recorded.</AbstractText>Forty-eight studies were included comprising 3832 patients: 2279 in group I and 1553 in group II. The mean duration of AF, left atrial diameter and LVEF were 5.4 versus 5.5 years (p=0.90), 55.5 versus 57.8 mm (p=0.23) and 57 versus 58% (p=0.63). The postoperative SR rates for group I and II were 78.3 versus 84.9% (p=0.03). However, the "cut and sew" Cox-Maze III was conducted in younger patients (55.0 versus 61.2 years; p=0.005), more often to treat paroxysmal (22.9 versus 8.0%) and lone AF (19.3 versus 1.6%). Alternative sources of energy were predominantly used to treat permanent AF (92.0%), almost always as a concomitant surgical procedure (98.4%) and increasingly in combination with non-mitral valve surgery (18.5%). After correction for these variations, the postoperative SR conversion rates for group I and II did not differ significantly anymore.</AbstractText>We could not identify any significant difference in the postoperative SR conversion rates between the classical 'cut and sew' and the alternative sources of energy, which were used to treat atrial fibrillation.</AbstractText> |
8,495 | [History of rhythm surgery with focus on surgical ablation procedures to treate atrial fibrillation]. | Rhythm surgery, which was initiated many years ago, has fundamentally changed by the development of sparing interventional treatment procedures and the successful introduction of the implantable defibrillator.A cornerstone in the history was the first successful treatment of a patient with Wolff-Parkinson-White-Syndrome separating accessory conduction lines between atrium and ventricle in 1968. The experience and knowledge of the surgical therapy of the 70ies has promoted the implementation of successful interventional ablation procedures in the early 80ies.Further steps in the rapidly developing area of rhythm surgery were the left and right atrial isolation procedures for the treatment of automatically atrial tachycardia's, the use of cryo-surgery for AV-node ablation in patients with AV-re-entry tachycardia's in the 80ies and finally the procedures for the treatment of atrial fibrillation like the transsection procedure, the corridor operation and the Maze procedure. Special methods for the therapy of ventricular arrhythmias should be mentioned for the sake of completeness, but are not extensively discussed. These are the right ventricular disconnection procedure, endocardial and subendocardial resections, endocardial cryo-ablation, the Jatene- and Dor-operation for the treatment of ischemic ventricular arrhythmias. Out of the original indications, today the therapy of atrial fibrillation has become more and more important and represents a booming part of rhythm surgery in the last decade. The unsatisfactory results of medical treatment, new understanding of the pathophysiology of atrial fibrillation and the introduction of simplified ablation procedures have led to a markable increase of rhythm surgery procedures. One reason is the increasing life expectancy of the population leading to a higher incidence of atrial fibrillation, which makes this arrhythmia to the most common rhythm disturbance. This growing number of patients is a challenge for cardiac surgery today and leads the focus on this special part. |
8,496 | [Endovascular treatment of coronary arterial fistulae in children and adults]. | The authors report their experience of endovascular treatment of coronary fistulae in 25 patients aged 2 to 77 years (median 29 years) who underwent 30 interventional catheterisation procedures. The origin of the fistulae was variable: left coronary (14 cases), right coronary (6 cases) and bilateral (5 cases) as were the sites of drainage: right atrium (5 cases), right ventricle (8 cases) pulmonary artery (7 cases) and bronchial artery (5 cases). Different materials were used: releasable balloons (9 cases), coils (17 cases), microparticles (5 cases) and Amplatzer occluder and plug (2 cases). The result, judged by occlusion or sub-occlusion of the given pedicle, was a success in 92% of cases. Total or sub-total occlusion of the fistula was obtained in 22 patients (88%); 2 patients had residual fistulae due to non-embolisation of the pedicle; in one patient, it was not possible to embolise the pedicle despite two attempts. A single serious complication, ventricular fibrillation during the catheterisation, was observed but without a sequel. Follow-up ranged from 6 to 176 months; 4 patients died of other causes, 3 were lost to follow-up; one coronaro-pulmonary fistula recurred but no other recurrence was observed in the other patients. The authors conclude that embolisation is the treatment of choice for coronary fistulae providing the cases are managed by teams trained in the use of different materials. The choice of material of embolisation should be adapted to the anatomical conditions which determine the success rate and the absence of complications. |
8,497 | Clinical trials update from Heart Rhythm 2007 and Heart Failure 2007: CARISMA, PREPARE, DAVID II, SAVE-PACE, PROTECT and AREA-IN-CHF. | This article provides information and a commentary on trials relevant to the pathophysiology, prevention and treatment of heart failure, presented at Heart Rhythm 2007 organised by the Heart Rhythm Society which was held in Denver, USA and Heart Failure 2007 organised by the Heart Failure Association of the European Society of Cardiology which was held in Hamburg, Germany. Unpublished reports should be considered as preliminary data, as analyses may change in the final publication. The CARISMA study suggests that non-invasive screening tests may help to identify post-MI patients who may benefit from ICD therapy. Data from the PREPARE study show that more conservative ICD programming can reduce morbidity at the cost of an increased risk of arrhythmic syncope. DAVID II indicates that atrial pacing may be a safe alternative to ventricular back-up pacing in patients with left ventricular dysfunction and standard indications for an ICD. The incidence of persistent atrial fibrillation in patients with sinus node disease in SAVE-PACE was reduced by dual chamber minimal ventricular pacing compared to conventional dual chamber pacing. The pilot phase of the PROTECT studies confirmed 30 mg as the dose of the selective A1 adenosine receptor antagonist KW-3902 to be used in pivotal studies. AREA-IN-CHF failed to show a beneficial effect of canrenone on LV volumes compared to placebo however some beneficial effects on secondary clinical endpoints were observed. |
8,498 | Rescue shock outcomes during out-of-hospital cardiac arrest. | Questions remain about the optimal timing and method for treating ventricular fibrillation (VF) during out-of-hospital cardiac arrest, and a variety of treatment protocols are used. Detailed description of rescue shock outcomes during actual patient care under different protocols would allow rational comparison of treatment strategies. The purpose of this study is to describe rescue shock outcomes in a single system using a specific defibrillation protocol.</AbstractText>Patient care records were examined for all adult (age> or =18 years) out-of-hospital cardiac arrest cases treated by an urban paramedic system during a 52-month interval. The immediate outcomes of monophasic rescue shocks were determined from the record and were classified as asystole, VF, restoration of organized electrical activity (ROEA), or restoration of spontaneous circulation (ROSC).</AbstractText>Among 1496 cases of cardiac arrest, 654 received a median of 3 (IQR 1,5) rescue shocks. Of these cases, 408 (28%) had an initial rhythm of VF whereas VF developed later during resuscitation in the remainder. For an initial series of three escalating rescue shocks, most cases of ROSC (9%) and ROEA (12%) occurred after the first shock. The likelihood that a rescue shock would result in ROSC or ROEA increased with witnessed collapse, and rescue shock number. An initial rhythm of asystole was associated with a decreased likelihood that a rescue shock would result in ROEA.</AbstractText>Witnessed collapse and an initial rhythm other than asystole were associated with an increased likelihood of rescue shock success. There is a small but real incremental gain in ROSC and ROEA from delivering three rescue shocks in rapid succession. The greater incidence of rescue shock success with later rescue shocks suggests that VF responds favorably to ongoing resuscitation.</AbstractText> |
8,499 | Myocardial performance index following electrically induced or ischemically induced cardiac arrest. | We sought to investigate the echocardiographic myocardial performance index (MPI) to assess post-resuscitation myocardial function following electrically and ischemically induced ventricular fibrillation (VF).</AbstractText>VF was induced in fourteen anesthetized pigs weighing 38+/-4 kg. VF was induced electrically in seven animals and ischemically, following transient occlusion of the left anterior descending coronary artery (LAD), in the remaining seven animals. VF was untreated for 7 min after which CPR, including precordial compression and mechanical ventilation was begun. Defibrillation was attempted after 5 min of CPR. MPI, ejection fraction (EF) and fractional area change (FAC) were measured hourly during the following 4 h interval post-resuscitation.</AbstractText>Five of seven animals were resuscitated in the electrically induced VF group, and four of seven animals in the ischemically induced VF group. No difference in EF and FAC were observed between the two groups. The MPI, however, was significantly greater at 60 min and 120 min post-resuscitation in animals after ischemically induced VF (p<0.05).</AbstractText>In this model, left ventricular (LV) MPI was a more sensitive and useful quantitative parameter to assess the LV function than the EF and FAC measurements used routinely. MPI measurements indicated that post-resuscitation myocardial dysfunction may be more severe after ischemically induced VF compared to the electrically induced VF.</AbstractText> |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.