Unnamed: 0 int64 0 2.34M | titles stringlengths 5 21.5M | abst stringlengths 1 21.5M |
|---|---|---|
8,600 | Left atrial remodelling in mitral regurgitation--methodologic approach, physiological determinants, and outcome implications: a prospective quantitative Doppler-echocardiographic and electron beam-computed tomographic study. | To define accurate and normal range of echocardiographic left atrial (LA) volume measurement and to assess the prevalence, determinants, and outcome implications of LA enlargement in mitral regurgitation (MR).</AbstractText>We prospectively compared LA volume obtained simultaneously by electron beam-computed tomography (EBCT) and by four echocardiographic methods in 33 test patients. Accurate echocardiographic LA volume measurements were obtained only by biplane area-length method with vertical longitudinal-length (r = 0.95, P < 0.0001; 145 +/- 57 vs. 143 +/- 55 mL, P = 0.57). Using this method, the normal range in 100 normal subjects, the physiological determinants and outcome implications of LA enlargement in 320 patients with organic MR were analysed. In normal subjects, indexed to body surface area, LA index (27 +/- 6 mL/m(2)) was not influenced by age or gender and values > or = 40 mL/m(2) were beyond the upper limit of normal. In MR, the most powerful determinants of LA enlargement were higher regurgitant volume (RVol) and atrial fibrillation (AF) (P < 0.0001), followed by older age, female gender, higher left ventricular end-systolic volume, and mass (all P < 0.001). After diagnosis in sinus rhythm, LA index > or = 40 mL/m(2) predicted superiorly and independently to LA diameter the occurrence of AF [adjusted RR 1.48 (1.06-2.16), P < 0.01] and the combined endpoint of death or need for mitral surgery [adjusted RR 1.61 (1.3-2.0), P < 0.0001].</AbstractText>LA remodelling can be accurately assessed by echocardiography and LA index > or = 40 mL/m(2) is beyond the normal range. In organic MR, higher LA index is the combined result of multiple physiological effects, provides independent prognostic information, and therefore should be part of a comprehensive echocardiographic examination.</AbstractText> |
8,601 | [Ventricular fibrillation after administration of succinylcholine].<Pagination><StartPage>209</StartPage><EndPage>210</EndPage><MedlinePgn>209-10</MedlinePgn></Pagination><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>García</LastName><ForeName>M</ForeName><Initials>M</Initials></Author><Author ValidYN="Y"><LastName>Santana</LastName><ForeName>L</ForeName><Initials>L</Initials></Author><Author ValidYN="Y"><LastName>Ramírez</LastName><ForeName>A</ForeName><Initials>A</Initials></Author><Author ValidYN="Y"><LastName>Sánchez-Palacios</LastName><ForeName>Y M</ForeName><Initials>YM</Initials></Author></AuthorList><Language>spa</Language><PublicationTypeList><PublicationType UI="D002363">Case Reports</PublicationType><PublicationType UI="D016422">Letter</PublicationType></PublicationTypeList><VernacularTitle>Fibrilación ventricular tras la administración de succinilcolina.</VernacularTitle></Article><MedlineJournalInfo><Country>Spain</Country><MedlineTA>Med Intensiva</MedlineTA><NlmUniqueID>9207689</NlmUniqueID><ISSNLinking>0210-5691</ISSNLinking></MedlineJournalInfo><ChemicalList><Chemical><RegistryNumber>0</RegistryNumber><NameOfSubstance UI="D009467">Neuromuscular Depolarizing Agents</NameOfSubstance></Chemical><Chemical><RegistryNumber>J2R869A8YF</RegistryNumber><NameOfSubstance UI="D013390">Succinylcholine</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000328" MajorTopicYN="N">Adult</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008297" MajorTopicYN="N">Male</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D009467" MajorTopicYN="N">Neuromuscular Depolarizing Agents</DescriptorName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D013390" MajorTopicYN="N">Succinylcholine</DescriptorName><QualifierName UI="Q000009" MajorTopicYN="Y">adverse effects</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D014693" MajorTopicYN="N">Ventricular Fibrillation</DescriptorName><QualifierName UI="Q000139" MajorTopicYN="Y">chemically induced</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2007</Year><Month>6</Month><Day>15</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2007</Year><Month>10</Month><Day>30</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2007</Year><Month>6</Month><Day>15</Day><Hour>9</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">17562309</ArticleId><ArticleId IdType="doi">10.1016/s0210-5691(07)74810-6</ArticleId><ArticleId IdType="pii">13106832</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">17561644</PMID><DateCompleted><Year>2007</Year><Month>07</Month><Day>10</Day></DateCompleted><DateRevised><Year>2016</Year><Month>10</Month><Day>20</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0869-6047</ISSN><JournalIssue CitedMedium="Print"><Issue>4</Issue><PubDate><Year>2007</Year></PubDate></JournalIssue><Title>Vestnik Rossiiskoi akademii meditsinskikh nauk</Title><ISOAbbreviation>Vestn Ross Akad Med Nauk</ISOAbbreviation></Journal>[The prospectivity of permanent cardiostimulation for prevention of atrial fibrillation]. | Possibility of prevention of atrial fibrillation in patients with permanent pacemakers was analyzed taking into account induction mechanisms. Patients with bradicardiac and ectopic mechanisms of atrial fibrillation induction seem to be optimal candidates for pacemaker therapy. Right ventricular pacing was an independent predictor of arrhythmic events. |
8,602 | Usefulness of percutaneous left ventricular assist device as a bridge to recovery from myocarditis. | The TandemHeart percutaneous left ventricular assist device is a left atrial-to-femoral artery bypass system that can be implanted percutaneously within 30 minutes and provides active circulatory support. The TandemHeart has been used mainly for temporary hemodynamic assistance during high-risk coronary interventions and postcardiotomy heart failure. This report describes initial experience with this device as a successful bridge to cardiac recovery in 3 patients with acute myocarditis. All patients presented with severe cardiogenic shock (mean cardiac index 1.1 L/min/m2), and end-organ perfusion could not be maintained despite intra-aortic balloon counterpulsation and the maximal use of vasopressive agents. The patients were successfully bridged to myocardial recovery with the TandemHeart (mean duration of support 5 days, range 2 to 8). The only complication was a short episode of ventricular fibrillation during device placement in 1 patient, which did not result in any morbidity or mortality. All patients were discharged home (mean duration of stay 15 days). In conclusion, the TandemHeart proved to be a safe and effective bridge to myocardial recovery in these patients with acute myocarditis. |
8,603 | Clinical and echocardiographic markers of mortality risk in patients with atrial fibrillation. | Atrial fibrillation (AF) is independently associated with increases in cardiovascular and all-cause mortality. Although cardiovascular co-morbidities predict stroke risk in AF, their relation with mortality has not been well described. To identify clinical and echocardiographic markers of mortality in patients with AF, 524 patients with AF underwent transesophageal echocardiography from August 2000 to March 2005. Clinical risk factors for systemic thromboembolism were determined for each patient. A CHADS2 (congestive heart failure, hypertension, age>75 years, diabetes, and previous stroke or transient ischemic attack) score ranging from 0 to 6 was calculated for each patient. Transesophageal echocardiographic reports were reviewed for the presence of left atrial spontaneous echocardiographic contrast, left atrial thrombus, the left ventricular ejection fraction, aortic arch atheroma, and the presence and severity of mitral regurgitation. Mortality data were obtained from the Social Security Death Master File. Univariate and multivariate models were structured to assess which variables predicted mortality. In a multivariate model, a history of heart failure, age>75 years, the absence of systemic anticoagulation with warfarin, the presence of left atrial spontaneous echocardiographic contrast, and greater than moderate mitral regurgitation were independent predictors of mortality. Increasing CHADS2 score was also an independent predictor of mortality. A CHADS2 score of 5 or 6 was associated with a >50-fold increase in mortality compared with patients with CHADS2 scores of 0. In conclusion, a history of heart failure, age>or=75 years, the absence of chronic oral anticoagulation, a CHADS2 score>0, and greater than moderate mitral regurgitation are independent predictors of mortality in patients with AF. |
8,604 | Body mass index is an independent determinant of left atrial size. | Obesity is a risk factor for atrial fibrillation (AF) but the mechanisms underlying this association are unclear. We aimed to assess whether body mass index (BMI) is an independent determinant of left atrial size, in subjects in sinus rhythm.</AbstractText>Subjects were consecutive ambulatory patients aged >/=18 years who underwent outpatient transthoracic echocardiography at a major metropolitan teaching hospital in Sydney, Australia. At the time of examination, age, sex, height and weight were measured. Left atrial (LA) area was measured on ultrasound by planimetry. Left ventricular (LV) function and LV posterior wall thickness were measured by M-mode.</AbstractText>Of 4859 consecutive subjects who underwent outpatient echocardiography at our institution over a three-year period, we analysed echocardiographic data from 2534 aged >/=18 years with confirmed sinus rhythm, normal LV contractility and no evidence of significant aortic or mitral valve disease. In these subjects (age 47+/-16.6 years, BMI 27.1+/-6.1, 53% male), BMI was a significant predictor of LA size (p<0.001), independent of the significant influences of LV end-diastolic volume and LV posterior wall thickness. Average LA size was 18.5+/-4.0 cm(2) in those with normal BMI, 20.7+/-4.5 cm(2) in the overweight and 22.3+/-4.1cm(2) in obese subjects (p for trend <0.001).</AbstractText>Obesity is associated with increased left atrial size in subjects undergoing clinically indicated echocardiography, independent of the effects of left ventricular size and posterior wall thickness. This may contribute, at least in part, to the rising incidence of atrial fibrillation in the community.</AbstractText> |
8,605 | Biliopancreatic diversion reduces QT interval and dispersion in severely obese patients. | The objectives were to evaluate QT interval (QTc) and QT-interval dispersion (QTd) in severely obese individuals and to determine the effects of biliopancreatic diversion (BPD) and weight loss after BPD on ventricular repolarization parameters.</AbstractText>People with severe obesity (SO) have a 50% to 100% increased risk of death associated with a 1.6-fold increased risk of sudden death. BPD surgery induces rapid and considerable weight loss through severe lipid malabsorption, thus achieving long-term weight control.</AbstractText>A total of 85 subjects with SO (age, 42 +/- 12 years; 66 females; mean body weight, 120 +/- 29 kg; BMI, 45 +/- 11 kg/m(2)) of 330 who had a bariatric surgical consultation between January 2001 and July 2002 were enrolled. Inclusion criteria were sinus rhythm, unremarkable 12 leads surface electrocardiogram, no atrioventricular blocks and/or bundle branch blocks, normal serum electrolyte profile, and no medical therapies exerting known effects on QTc. Exclusion criteria were previous diagnosis of coronary artery disease, known cardiovascular disease, atrial fibrillation or any other known cardiac arrhythmias, cancer, or renal dysfunction.</AbstractText>A total of 86% of patients had QTc >440 ms and/or QTd >60 ms. Subjects with SO showed a mean maximum QTc of 446 +/- 28 ms and a mean QTd of 52 +/- 20 ms. A close correlation was found between QTc and QTd (p < 0.0001; R(2) = 0.33). One month after BPD, mean QTc was 420 ms and remained stable at follow-up; QTd was 32 ms at 1 and 6 months and became 35 ms at 1 year.</AbstractText>Ventricular repolarization abnormalities are significantly increased in subjects with SO. Reduction of QT abnormalities after BPD is independent of weight loss and is caused by the 100% reduction of glucose plasma shortly after surgery. This effect may be related to surgical interruption of the entero-insular axis.</AbstractText> |
8,606 | Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks. | Earliest recorded postshock myocardial activations in pigs originate in the subepicardium of the apex and lateral free wall of the left ventricle (LV) 30-90 ms after the shock.</AbstractText>The purpose of this study was to determine whether the Purkinje system is a candidate for the source of postshock activations by performing endocardial and transmural postshock activation mapping.</AbstractText>In five pigs, 32 plunge needles with 12 electrodes (1-mm spacing) were inserted into the LV apex and lateral free wall. Up to 70 plunge needles with six electrodes (2-mm spacing) were spread throughout the remainder of the LV, while 9-12 plunge needles with four electrodes (2-mm spacing) were inserted into the right ventricle. A basket catheter with 32 bipolar recording sites was inserted into the LV. Defibrillation-threshold (DFT)-level shocks were delivered during 10 episodes of electrically induced ventricular fibrillation. Electrograms of postshock activation cycles were analyzed for Purkinje and myocardial activations.</AbstractText>Purkinje activations were recorded before local myocardial activation in 9% of basket electrograms and in 15% of plunge needles during the first postshock activation cycle. Purkinje activations were identified during the first and subsequent several postshock activation cycles in at least one basket and one needle electrogram in 96% and 98% of defibrillation episodes, respectively.</AbstractText>The Purkinje system is active during the early postshock activation cycles after DFT-level shocks. Further studies are required to determine whether activation initiates in the Purkinje system or whether it is activated by the myocardium or by Purkinje-myocardial junctional cells.</AbstractText> |
8,607 | Acute and chronic management in patients with Brugada syndrome associated with electrical storm of ventricular fibrillation. | Some patients with Brugada syndrome experience an electrical storm of ventricular fibrillation (VF).</AbstractText>The purpose of this study was to investigate the clinical, laboratory, electrocardiographic, and electrophysiologic characteristics, acute and subsequent chronic treatment, and follow-up data of patients with Brugada syndrome associated with electrical storm of VF.</AbstractText>Sixty-seven patients with Brugada syndrome (65 men and 2 women, age 46 +/- 14 years) were divided into three groups: 7 patients with a history of electrical storm of VF (group I), 39 symptomatic patients with documented VF and/or syncope (group II), and 21 asymptomatic patients (group III). Electrical storm was defined as three or more episodes of VF per day recorded by the memory of an implantable cardioverter-defibrillator.</AbstractText>No significant differences were observed among the three groups with regard to clinical (age at diagnosis, familial history of sudden cardiac death), laboratory (SCN5A mutation and serum potassium level), electrocardiographic and electrophysiologic characteristics, and follow-up duration after diagnosis. However, arrhythmic events during follow-up after diagnosis and number of arrhythmic events per patient were significantly higher in group I compared with groups II and III. Isoproterenol infusion (0.003 +/- 0.003 microg/kg/min for 24 +/- 13 days) completely suppressed electrical storm of VF in all five patients treated and was successfully replaced with oral medications, including denopamine, quinidine, isoproterenol, cilostazol, and bepridil alone or in combination.</AbstractText>No specifically clinical, laboratory, electrocardiographic, and electrophysiologic characteristics were recognized in patients with Brugada syndrome associated with electrical storm of VF. Isoproterenol infusion was effective as an acute treatment in suppressing electrical storm of VF and was successfully replaced with chronic oral medications.</AbstractText> |
8,608 | Efficacy of therapeutic hypothermia after out-of-hospital cardiac arrest due to ventricular fibrillation. | We investigated implementation and efficacy of mild therapeutic hypothermia in the treatment of out-of-hospital cardiac arrest due to ventricular fibrillation.</AbstractText>Two periods were compared, an historical one (36 patients) between 2000 and 2002 where therapeutic hypothermia was never used, and a recent period (32 patients) between 2003 and 2005 where therapeutic hypothermia (32-34 degrees C) was implemented prospectively in our unit. Cooling was obtained by simply using wet cloths and ice packs. Survival in the two groups and factors associated with survival were analysed, together with the neurological prognosis in discharged patients.</AbstractText>Survival was significantly higher in the hypothermia group (56% versus 36%), whereas no significant difference was observed in severity between the two periods. Only age, time from return to spontaneous circulation <20min, and therapeutic hypothermia were independently associated with survival. Therapeutic hypothermia was well tolerated and was associated with a significant improvement in neurological outcome. Whereas only 23% of patients actually reached the target temperature in 2003, 100% did in 2005.</AbstractText>Therapeutic hypothermia is efficient in significantly improving survival and neurological outcome of out-of-hospital cardiac arrest with ventricular fibrillation. By using a simple method, it can be implemented easily and quickly, without side effects.</AbstractText> |
8,609 | Heterogeneity of ventricular fibrillation dominant frequency during global ischemia in isolated rabbit hearts. | Ventricular fibrillation (VF) studies show that ECG-dominant frequency (DF) decreases as ischemia develops. This study investigates the contribution of the principle ischemic metabolic components to this decline.</AbstractText>Rabbit hearts were Langendorff-perfused at 40 mL/min with Tyrode's solution and loaded with RH237. Epicardial optical action potentials were recorded with a photodiode array (256 sites, 15 x 15 mm). After 60 seconds of VF (induced by burst pacing), global ischemia was produced by low flow (6 mL/min), or the solution changed to impose hypoxia (95% N2/5% CO2), low pH(o) (6.7, 80% O2/20% CO2), or raised [K+](o) (8 mM). DF of the optical signals was determined at each site. Conduction velocity (CV), action potential duration (APD90), effective refractory period (ERP), activation threshold, dV/dt(max), and membrane potential were measured in separate experiments during ventricular pacing. During VF, ischemia decreased DF in the left ventricle (LV) (to [58 +/- 6]%, P < 0.001), but not the right (RV) ([93 +/- 5]%). Raised [K+](o) reproduced this DF pattern (LV: [67 +/- 12]%, P < 0.001; RV: [95 +/- 9]%). LV DF remained elevated in hypoxia or low pH(o). During ventricular pacing, ischemia decreased CV in LV but not RV. Raised [K+](o) did not change CV in either ventricle. Ischemia and raised [K+](o) shortened APD90 without altering ERP. LV activation threshold increased in both ischemia and raised [K+](o) and was associated with diastolic depolarization and decreased dV/dt(max).</AbstractText>These results suggest that during VF, decreased ECG DF in global ischemia is largely due to elevated [K+](o) affecting the activation thresholds in the LV rather than RV.</AbstractText> |
8,610 | Postprandial augmentation of bradycardia-dependent ST elevation in patients with Brugada syndrome. | In patients with Brugada syndrome, the circadian variation of ST elevation could be modulated by the autonomic nervous activity and RR interval. Recently, glucose-induced insulin secretion was also reported to contribute to fluctuation of ST elevation. Therefore, we assessed the effects of taking meals on the ST-RR relationship in the daily life of patients with Brugada syndrome.</AbstractText>Twenty-eight patients with Brugada syndrome, who had the type I ST elevation, were categorized into 12 symptomatic and 16 asymptomatic patients. Unipolar lead (V2) Holter ECG was recorded and ST-RR relationships for a 2-hour period were compared before and after each meal. From ST-RR linear regression lines, ST-RR slope (mm/sec) and ST(mm) at RR intervals of both 0.6 seconds and 1.2 seconds (ST(0.6) and ST(1.2)) were determined. The ST-RR slope increased significantly after lunch (2.6 +/- 0.4 vs 4.4 +/- 1.2, P < 0.05) and dinner (2.1 +/- 1.0 vs 5.2 +/- 1.9, P < 0.01) in symptomatic patients, but not in asymptomatic patients. In both groups, ST(0.6) was not different before or after each meal. However, ST(1.2) increased after each meal in symptomatic patients. After dinner, ST(1.2) was significantly higher in symptomatic patients than in asymptomatic patients (5.0 +/- 2.7 vs 3.6 +/- 0.8, P < 0.05). Postprandial increase in both ST-RR slope and ST(1.2) was greatest at dinner in symptomatic patients; however, this tendency was not seen in asymptomatic patients.</AbstractText>In symptomatic patients with Brugada syndrome, bradycardia-dependent augmentation of ST elevation was enhanced for the postprandial period, especially after dinner. This could be related to occurrence of ventricular fibrillation in the late evening.</AbstractText> |
8,611 | Rare survival in a patient with severe complications of acute myocardial infarction: a case report. | A 50-year-old man presented with acute myocardial infarction. Coronary angiography showed the left anterior descending artery (segment 6) was totally occluded. Direct percutaneous transluminal coronary angioplasty was performed, but a distal embolism occurred by the procedure. Consequently, he suffered cardiogenic shock and sustained ventricular tachycardia/fibrillation which exacerbated his condition. Finally, the patient was successfully treated with catheter ablation and cryosurgery to control the incessant ventricular arrhythmias, and partial left ventricular volume reduction and coronary artery bypass grafting to improve contractile performance. His left ventricular contractility did not improve, but the incessant ventricular arrhythmias could be controlled. His condition remarkably improved and he was discharged on foot. This patient with severe complications of acute myocardial infarction showed unusually good response and recovery. |
8,612 | The quality of chest compressions during cardiopulmonary resuscitation overrides importance of timing of defibrillation. | We address the quality of chest compressions and the impact on initial defibrillation or initial chest compressions after sudden death.</AbstractText>Ventricular fibrillation was induced by occlusion of the left anterior descending coronary artery in 24 domestic pigs with a mean (+/- SD) weight of 40 +/- 2 kg. Cardiac arrest was left untreated for 5 min. Animals were then randomized to receive chest compressions-first or defibrillation-first and were further randomized to "optimal" or "conventional" chest compressions. A total of four groups of animals were investigated using a factorial design. For optimal chest compressions, the anterior posterior diameter of the chest was reduced by 25%, representing approximately 6 cm. Only 70% of this depth, or approximately 4.2 cm, represented conventional chest compressions. Chest compressions were delivered with a mechanical chest compressor. Defibrillation was attempted with a single biphasic 150-J shock. Postresuscitation myocardial function was echocardiographically assessed.</AbstractText>Coronary perfusion pressures and end-tidal Pco(2) were significantly lower with conventional chest compressions. With optimal chest compressions, either as an initial intervention or after defibrillation, each animal was successfully resuscitated. Fewer shocks were required prior to the return of spontaneous circulation after initial optimal chest compressions. No animals were resuscitated when conventional chest compressions preceded the defibrillation attempt. When defibrillation was attempted as the initial intervention followed by conventional chest compressions, two of six animals were resuscitated.</AbstractText>In this animal model of cardiac arrest, it was the quality of the chest compressions, rather then the priority of either initial defibrillation or initial chest compressions, that was the predominant determinant of successful resuscitation.</AbstractText> |
8,613 | Parameters characterizing implantable defibrillator output: a proposal. | Recently, a discussion was carried out in Heart Rhythm on the specifications that could characterize implantable defibrillators. It is the intention of this paper to participate in this discussion on defibrillation characteristics and to give recommendations on how this problem could be solved. Theoretical considerations and results There are different defibrillation theories, all finding that the defibrillation's efficacy depends on the time constant RC which is output capacitance C times load resistance R. Efficacy decreases with increasing RC. This means that (i) the knowledge of C is of paramount importance, (ii) the energy is 'devalued' with increasing RC and that those parameter settings such as tilt or pulse duration should be adjusted to the time constant, and (iii) the energy values given without further specification are not meaningful. As there is always a voltage drop across an internal resistance within the ICD, the measured voltage across the output differs from the capacitor voltage and is reduced which determines the efficiency of the device. From the data given by Thammanomai et al., one can determine the parameters maximum voltage, capacitance, internal resistance, and tilt. These parameters are adequate and necessary to describe an ICD device and to derive the effective energy for device comparison. Discussion The 'high output devices' with their high nominal energy are reduced in their effective energies to a degree that they are comparable to the best 'standard output devices'. They do not offer that superiority which is promised by the nominal energy. Moreover, if the tilt is fixed and larger than optimal, the energy requirements are still higher or the effective energy will further drop. The term 'delivered energy' is not used by us because the delivered energy increases with increasing tilt. However, today's tilts are too large as judged by theories, which means that high delivered energies can be worse than lower ones. The delivered energy is, therefore, not a meaningful parameter in judging ICDs.</AbstractText>ICD devices should be characterized by: (i) voltage, (ii) capacitance, (iii) tilt or pulse duration (if not programmable), and (iv) internal resistance. All other parameters can be derived from them by simple calculations. Introduction of a 'devaluation factor' characterizes the decreasing efficacy with increasing time constant and renders the output characteristics transparent and comparable.</AbstractText> |
8,614 | Exacerbation of acidosis during ischemia and reperfusion arrhythmia in hearts from type 2 Diabetic Otsuka Long-Evans Tokushima Fatty rats. | Sensitivity to ischemia and its underlying mechanisms in type 2 diabetic hearts are still largely unknown. Especially, correlation between reperfusion induced ventricular arrhythmia and changes in intracellular pH has not been elucidated.</AbstractText>Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats at 16 and 32 weeks of age were used along with age-matched nondiabetic Long-Evans Tokushima Otsuka (LETO) rats. Hearts from rats in these 4 groups were perfused in the working heart mode, thus inducing whole heart ischemia. At 16 weeks of age, no differences in blood glucose levels or incidence and duration of reperfusion arrhythmia were found between the strains. At 32 weeks of age, both impaired glucose tolerance and obesity were observed in the OLETF rats. Further, the duration of reperfusion-induced ventricular fibrillation (VF) was significantly longer in the OLETF rats, while the pH level was significantly lower and proton contents were significantly higher in coronary effluent during ischemia in those rats. Following treatment with troglitazone, improvements in pH and proton level in coronary effluent during ischemia were observed, as was the duration of reperfusion-induced VF in OLETF rats at 32 weeks of age.</AbstractText>The hearts of spontaneously diabetic OLETF rats were found to be more susceptible to ischemic insult. Troglitazone treatment improved ischemic tolerance by improving glucose metabolism in the myocardium of those rats.</AbstractText> |
8,615 | Pilot randomized clinical trial of prehospital induction of mild hypothermia in out-of-hospital cardiac arrest patients with a rapid infusion of 4 degrees C normal saline. | Although delayed hospital cooling has been demonstrated to improve outcome after cardiac arrest, in-field cooling started immediately after the return of spontaneous circulation may be more beneficial. The aims of the present pilot study were to assess the feasibility, safety, and effectiveness of in-field cooling.</AbstractText>We determined the effect on esophageal temperature, before hospital arrival, of infusing up to 2 L of 4 degrees C normal saline as soon as possible after resuscitation from out-of-hospital cardiac arrest. A total of 125 such patients were randomized to receive standard care with or without intravenous cooling. Of the 63 patients randomized to cooling, 49 (78%) received an infusion of 500 to 2000 mL of 4 degrees C normal saline before hospital arrival. These 63 patients experienced a mean temperature decrease of 1.24+/-1 degrees C with a hospital arrival temperature of 34.7 degrees C, whereas the 62 patients not randomized to cooling experienced a mean temperature increase of 0.10+/-0.94 degrees C (P<0.0001) with a hospital arrival temperature of 35.7 degrees C. In-field cooling was not associated with adverse consequences in terms of blood pressure, heart rate, arterial oxygenation, evidence for pulmonary edema on initial chest x-ray, or rearrest. Secondary end points of awakening and discharged alive from hospital trended toward improvement in ventricular fibrillation patients randomized to in-field cooling.</AbstractText>These pilot data suggest that infusion of up to 2 L of 4 degrees C normal saline in the field is feasible, safe, and effective in lowering temperature. We propose that the effect of this cooling method on neurological outcome after cardiac arrest be studied in larger numbers of patients, especially those whose initial rhythm is ventricular fibrillation.</AbstractText> |
8,616 | Angiotensin converting enzyme inhibitor and angiotensin receptor blockade use in relation to outcomes in anticoagulated patients with atrial fibrillation. | The renin-angiotensin-aldosterone-system (RAAS) plays an important role in atrial fibrillation (AF). Evidence shows that blocking the RAAS with angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) has a definite role in preventing new onset AF and in maintaining sinus rhythm in recurrent AF. Our aim was to determine if ACEI/ARB treatment was associated with clinical outcomes [stroke/systemic embolic events (SEE), mortality] in a controlled, anticoagulated AF population.</AbstractText>An ancillary retrospective cross-sectional and longitudinal analysis of participants in the Stroke Prevention using an ORal Thrombin Inhibitor in AF (SPORTIF) III and V trials, in relation to use (or nonuse) of ACEI/ARBs.</AbstractText>Rates of stroke/SEEs, mortality or major bleeding were no different between users and nonusers in the whole cohort, or in relation to the presence/absence of hypertension, coronary artery disease and previous stroke/transient ischaemic attack, nor amongst those aged <75 years. Patients aged > or = 75 years taking ACEIs or ARBs had lower mortality (HR 0.71, 95% CI 0.52-0.95), but no significant influence on other end-points was noted. Diabetics and those with left ventricular dysfunction on ximelagatran had a higher odds ratio of abnormal liver enzyme levels. There was no apparent benefit of ACEIs or ARBs on other event rates.</AbstractText>This analysis from two large randomized trials of anticoagulation has not demonstrated a significant benefit of ACEI or ARB use amongst AF patients, except amongst elderly subjects.</AbstractText> |
8,617 | Occurrence of "J waves" in 12-lead ECG as a marker of acute ischemia and their cellular basis. | The "J wave" (also referred to as "the Osborn wave,""the J deflection," or "the camel's hump") is a distinctive deflection occurring at the QRS-ST junction. In 1953, Dr. John Osborn described the "J wave" as an "injury current" resulting in ventricular fibrillation during experimental hypothermia. Although "J Wave" is supposed to be pathognomonic of hypothermia, it is seen in a host of other conditions such as hypercalcemia, brain injury, subarachnoid hemorrhage, cardiopulmonary arrest from over sedation, the Brugada syndrome, vasospastic angina, and idiopathic ventricular fibrillation. However, there is paucity of literature data as regards to ischemic etiology of "J Wave." In this article, we present a case where "J waves" were probably induced by ischemia. We also discuss the mechanism of ischemia-induced "J wave" accentuation and its prognostic implications. |
8,618 | Single chamber atrial pacing: a realistic option in sinus node disease: a long-term follow-up study of 213 patients. | Despite several decades of experience with atrial pacing, many centers do not apply this mode to any greater extent, mainly because of concerns for the development of future atrioventricular (AV) block or atrial fibrillation. Recent studies have emphasized possible negative effects of right ventricular stimulation, even when AV-synchrony is preserved, and have thus given rise to renewed interest in single chamber atrial pacing for sinus node disease.</AbstractText>This study presents the results of up to 19 years' follow-up of 213 patients with sinus node disease treated with atrial pacing with respect to survival and causes of death, development of atrial fibrillation and AV block, and total mode survival. Patients were divided into two groups: with or without associated atrial tachyarrhythmias at the time of implant. Results are given for all patients and for the two groups separately.</AbstractText>The mean follow-up time was 10.1 years. The survival of the entire group was lower after 10 years than that of an age and gender-matched general Swedish population. This was caused by patients with the brady-tachy syndrome (BT) having a significantly higher mortality rate than controls, whereas those with bradycardia only (B) had survival comparable to the general population. Permanent atrial fibrillation (AF) developed in 20% of patients and was significantly more common in patients with BT. The majority of patients with AF (78%) no longer needed any pacing, i.e., did not require ventricular stimulation due to slow ventricular rate. The annual incidence of high grade AV block was 1.8%. If patients with preexisting bundle branch block were excluded, the incidence was 1.6%. No fatal episode of AV block was seen. The overall mode survival at the end of follow-up was 75%, with 155 patients still with atrial pacemakers.</AbstractText>Atrial pacing is a safe and reliable mode of pacing in patients with sinus node disease, even in the very long-term.</AbstractText> |
8,619 | The pre-hospital phase of acute myocardial infarction: a national audit is needed in New Zealand. | The outcome of acute myocardial infarction is usually settled before the patient reaches hospital, because ventricular fibrillation, when it occurs, is most common soon after the onset of symptoms. Ventricular fibrillation can be treated as effectively by ambulance personnel as in hospital, and many more deaths can be prevented, mainly by timely defibrillation, for patients coming under ambulance care within 1 hour of onset than can be prevented by use of more recent treatment advances. Both patient performance in reporting symptoms promptly, and ambulance performance in responding to calls for help, need to be audited. A prolonged campaign to educate the public on the cause and symptoms of heart attack, and how to respond to them, is also necessary. |
8,620 | Role of p38 mitogen-activated protein kinase on cardiac dysfunction after hemorrhagic shock in rats. | Cardiac dysfunction is a well-known complication of hemorrhagic shock as a consequence of local inflammatory response. Several studies have indicated that p38 mitogen-activated protein kinase (MAPK) is a key mediator in organ dysfunction that is associated with the inflammatory state through the activation of proinflammatory cytokines such as TNF-alpha and IL-1beta. Whether the same applies to cardiac dysfunction after hemorrhagic shock has not been clearly determined. Therefore, in this study, the role of p38 MAPK on cardiac dysfunction after hemorrhagic shock was studied up to 5 h after a hemorrhage using FR167653, a specific inhibitor of p38 MAPK phosphorylation. The p38 MAPK phosphorylation, the cardiac mRNA expressions of TNF-alpha and IL-1beta, and intracardiac serum concentrations of each cytokine and creatine phosphokinase-MB isozyme increased after a hemorrhage. Activated neutrophil accumulation in the heart, histological inflammation-related injuries, and frequent ventricular arrhythmia were observed in the late phase after hemorrhagic shock. FR167653 inhibited these hemorrhagic changes except the induction of the primary hypotensive state. These results demonstrate that p38 MAPK phosphorylation in hemorrhagic shock plays an important role in the cardiac expression of the proinflammatory cytokines and in the development of cardiac dysfunction relative to the inflammatory responses. |
8,621 | Three distinct phases of VF during global ischemia in the isolated blood-perfused pig heart. | Changes in ventricular fibrillation (VF) organization occurring after the onset of global ischemia are relevant to defibrillation and survival but remain poorly understood. We hypothesized that ischemia-specific dynamic instability of the action potential (AP) causes a loss of spatiotemporal periodicity of propagation and broadening of the electrocardiogram (ECG) frequency spectrum during VF in the ischemic myocardium. We recorded voltage-sensitive fluorescence of di-4-ANEPPS (anterior left ventricle, 35 x 35 mm, 64 x 64 pixels) and the volume-conducted ECG in six blood-perfused hearts during 10 min of VF and global ischemia. We used coefficient of variation (CV) to estimate variability of AP amplitude, AP duration, and diastolic interval (CV-APA, CV-APD, and CV-DI, respectively). We computed excitation median frequency (Median_F), spectral width of the AP and ECG (SpW-AP and SpW-ECG, respectively), wavebreak incidence (WBI), and recurrence of propagation direction (RPD). We found three distinct phases of local VF dynamics: "relatively periodic" (<or=1 min, high Median_F, moderate AP variability, high WBI, low RPD), "highly periodic" (1-2 min, reduced Median_F, low AP variability, low WBI, high RPD), and "aperiodic" (3-10 min, low Median_F, high AP variability, high WBI, low RPD). In one experiment, spontaneous conversion from the aperiodic to the highly periodic phase occurred after 5 min of ischemia. The SpW-ECG was correlated with SpW-AP, CV-APD, and CV-APA. We conclude that 1) at least three distinct phases of VF dynamics are present in our model, and 2) the newly described aperiodic phase is related to ischemia-specific dynamic instability of the AP shape, which underlies broadening of the ECG spectrum during VF evolution. |
8,622 | Influence of channel subunit composition on L-type Ca2+ current kinetics and cardiac wave stability. | Previous studies have demonstrated that the slope of the function relating the action potential duration (APD) and the diastolic interval, known as the APD restitution curve, plays an important role in the initiation and maintenance of ventricular fibrillation. Since the APD restitution slope critically depends on the kinetics of the L-type Ca(2+) current, we hypothesized that manipulation of the subunit composition of these channels may represent a powerful strategy to control cardiac arrhythmias. We studied the kinetic properties of the human L-type Ca(2+) channel (Ca(v)1.2) coexpressed with the alpha(2)delta-subunit alone (alpha(1C) + alpha(2)delta) or in combination with beta(2a), beta(2b), or beta(3) subunits (alpha(1C) + alpha(2)delta + beta), using Ca(2+) as the charge carrier. We then incorporated the kinetic properties observed experimentally into the L-type Ca(2+) current mathematical model of the cardiac action potential to demonstrate that the APD restitution slope can be selectively controlled by altering the subunit composition of the Ca(2+) channel. Assuming that beta(2b) most closely resembles the native cardiac L-type Ca(2+) current, the absence of beta, as well as the coexpression of beta(2a), was found to flatten restitution slope and stabilize spiral waves. These results imply that subunit modification of L-type Ca(2+) channels can potentially be used as an antifibrillatory strategy. |
8,623 | Atrial fibrillation reduces the atrial impedance amplitude during cardiac cycle: a novel detection algorithm to improve recognition of atrial fibrillation in pacemaker patients. | In carriers of dual chamber pacemakers and implantable cardioverter-defibrillators (ICD), detection of atrial fibrillation (AF) is crucial for adequate mode switch function and to avoid inappropriate shock delivery. Detection algorithms rely on the atrial rate and on the relationship of atrial to ventricular intracardiac electrograms, but the relative portion of misclassified AF episodes remains high. Although myocardial impedance is a reliable indicator of contraction, little is known about atrial impedance as a marker of atrial arrhythmias. Methods During an electrophysiological study, we investigated the effect of induced AF on impedance at the right atrial free wall (RAFW) and right atrial appendage (RAA) in 20 patients. Using biphasic square-wave pulses (128 Hz, 200 microA/15 micros), impedance changes were recorded during sinus rhythm (SR-1), atrial pacing at 120 beats/min, AF induced by rapid atrial burst pacing, and after spontaneous AF termination (SR-2). Results At the RAA, peak-to-peak impedance amplitude during cardiac cycle (DeltaZ) dropped from 51.7 +/- 35.3 Omega (SR-1) or 49.6 +/- 30.6 Omega (pacing) to 24.6 +/- 22.0 Omega (AF, P< or =0.0005), and subsequently increased to 37.7 +/- 24.7 Omega (SR-2, P < or = 0.0004 v. AF). At the RAFW, DeltaZ changed from 16.2 +/- 15.5 Omega (SR-1) or 13.5 +/- 9.9 Omega (pacing) to 5.9 +/- 4.1 Omega (AF, P < or = 0.003), and to 11.4 +/- 10.7 Omega (SR-2, P < or = 0.015). Given a discrimination threshold of 65%, the sensitivity and the specificity of DeltaZ to detect AF were 79 +/- 18 and 89 +/- 14%, respectively (95% confidence interval).</AbstractText>AF causes DeltaZ drop in pacemaker and ICD recipients. This impedance based algorithm can be used as an alternative method of AF detection.</AbstractText> |
8,624 | Effects of pericardial lidocaine on hemodynamic parameters and responses in dogs anesthetized with midazolam and fentanyl. | Tachycardia during anesthesia should be avoided, especially during off-pump coronary artery bypass graft surgery. Decreasing heart rate without reducing cardiac contractility is an ideal goal. To achieve this, the authors attempted to block the cardiac nerves by pericardial administration of local anesthetic.</AbstractText>A prospective study.</AbstractText>A laboratory.</AbstractText>Anesthetized, mechanically ventilated dogs (n = 69).</AbstractText>The pericardial space was infused with 2.5 or 5 mL of 1% lidocaine, 5 mL of 2% lidocaine, or normal saline solution. The hemodynamic changes and the cardiac responses to atropine or isoproterenol were measured during cardiac nerve blockade. To examine the inhibitory action of pericardial lidocaine on arrhythmias, an electrical fibrillator was installed. Furthermore, the blood level of lidocaine was measured.</AbstractText>Pericardial injection of lidocaine significantly decreased heart rate without a change in stroke volume. Under pericardial lidocaine, the tachycardia response to isoproterenol was similar to that observed without pericardial lidocaine, but response to atropine was significantly reduced. Pericardial lidocaine increased the voltage thresholds for inducing arrhythmias and ventricular fibrillation. Intravenous injection of lidocaine elevated the plasma concentration of lidocaine immediately, whereas the plasma concentration peaked at 10 minutes after pericardial administration.</AbstractText>Pericardial lidocaine (1) decreased heart rate without affecting stroke volume, (2) preserved the tachycardiac response to isoproterenol but completely blocked the response to atropine, and (3) increased the voltage thresholds for arrhythmias and ventricular fibrillation induced by an electrical fibrillator. These results suggest that pericardial lidocaine may be useful for controlling heart rate during off-pump coronary artery bypass graft surgery.</AbstractText> |
8,625 | Atrial fibrillation in the Wolff-Parkinson-White syndrome: ECG recognition and treatment in the ED. | Estimated to occur in 0.1% to 0.3% of the population, Wolff-Parkinson-White syndrome (WPW) is a condition where atrial impulses bypass the atrioventricular node and activate the ventricular myocardium directly via an accessory pathway. Clinical clues to the diagnosis include a young patient with previous episodes of palpitations, rapid heart rate, or syncope. Although several different rhythm presentations are possible, atrial fibrillation is a not infrequent dysrhythmia seen in the WPW patient. Electrocardiographic features suggestive of WPW atrial fibrillation include irregularity of the rhythm; a very rapid ventricular response; presence of a delta wave; and a wide, bizarre QRS complex. Stable patients suspected of having this condition should not receive agents that predominantly block atrioventricular conduction, but they may be treated with procainamide or ibutilide. If instability is present, electrical cardioversion is required. |
8,626 | Thrombolytic therapy vs primary percutaneous intervention after ventricular fibrillation cardiac arrest due to acute ST-segment elevation myocardial infarction and its effect on outcome. | The aim of this study was to evaluate the effect of thrombolytic therapy on neurologic outcome and mortality in patients after cardiac arrest due to acute ST-elevation myocardial infarction and to compare this with those in patients treated with primary percutaneous coronary intervention (PCI). We retrospectively examined patients after they had ventricular fibrillation cardiac arrests. To assess the effect of thrombolysis and PCI on outcome, we used odds ratios and their 95% confidence intervals and logistic regression modeling. Thrombolysis was applied in 101 patients (69%) and PCI in 46 patients (31%). More patients who received thrombolysis had favorable functional neurologic recovery (cerebral performance category 1 and 2) and survived to 6 months compared with patients with primary PCI (P = .38 and P = .13, respectively). In patients with cardiac arrest due to ST-elevation myocardial infarction, it may be acceptable to use thrombolysis as a reperfusion strategy. This applies especially in hospitals where immediate PCI is not available. |
8,627 | Epinephrine, but not vasopressin, improves survival rates in an adult rabbit model of asphyxia cardiac arrest. | Although vasopressin has been reported to be more effective than epinephrine for cardiopulmonary resuscitation in ventricular fibrillation animal models, its efficacy in asphyxia model remains controversy. The purpose of this study was to investigate the effectiveness of vasopressin vs epinephrine on restoration of spontaneous circulation (ROSC) in a rabbit model of asphyxia cardiac arrest. Cardiac arrest was induced by clamping endotracheal tube. After 5 minutes of basic life-support cardiopulmonary resuscitation, animals who had no ROSC were randomly assigned to receive either epinephrine alone (epinephrine group; 200 microg/kg) or vasopressin alone (vasopressin group; 0.8 U/kg). The coronary perfusion pressure (CPP) was calculated as the difference between the minimal diastolic aortic and simultaneously recorded right atrial pressure. Restoration of spontaneous circulation was defined as an unassisted pulse with a systolic arterial pressure of 60 mm Hg or higher for 5 minutes or longer. We induced arrest in 62 rabbits, 15 of whom had ROSC before drug administration and were excluded from analysis. The remaining 47 rabbits were randomized to epinephrine group (n = 24) and vasopressin group (n = 23). Before and after drug administration, CPP in epinephrine group increased significantly (from -4 +/- 4 to 36 +/- 9 mm Hg at peak value, P = .000), whereas CPP in vasopressin group increased only slightly (from 9 +/- 5 to 18 +/- 6 mm Hg at peak value, P = .20). After drug administration, 13 of 24 epinephrine rabbit had ROSC, and only 2 of 23 vasopressin rabbit had ROSC (P < .01). Consequently, we conclude that epinephrine, but not vasopressin, increases survival rates in this adult rabbit asphyxia model. |
8,628 | Can untrained laypersons use a defibrillator with dispatcher assistance? | Automated external defibrillators (AEDs) provide an opportunity to improve survival in out-of-hospital cardiac arrest by enabling laypersons not trained in rhythm recognition to deliver lifesaving therapy. This study was performed to examine whether untrained laypersons could safely and effectively use these AEDs with telephone-guided instructions and if this action would compromise the performance of cardiopulmonary resuscitation (CPR) during a simulated ventricular fibrillation out-of-hospital cardiac arrest.</AbstractText>Fifty-four conscripts without previous medical education were recruited from the Western Command in Finland. For this study, the participants were divided at random to form teams of two persons. The teams were randomized to dispatcher-assisted CPR with or without AED operation during a simulated ventricular fibrillation out-of-hospital cardiac arrest. The time interval from collapse to first shock, hands-off time, and the quality of CPR were compared between the two groups.</AbstractText>The quality of CPR was poor in both groups. The use of an AED did not increase the hands-off time or the time interval to the first compression. Sixty-four percent of the teams in the AED group managed to give the first defibrillatory shock within 5 minutes.</AbstractText>The quality of dispatcher-assisted CPR is poor. Dispatcher assistance in defibrillation by a layperson not trained to use an AED seems feasible and does not compromise the performance of CPR.</AbstractText> |
8,629 | Organization of ventricular fibrillation in the human heart. | Sudden cardiac death is a major cause of death in the industrialized world, claiming approximately 300,000 victims annually in the United States alone. In most cases, sudden cardiac death is caused by ventricular fibrillation (VF). Experimental studies in large animal hearts have shown that the uncoordinated contractions during VF are caused by large numbers of chaotically wandering reentrant waves of electrical activity. However, recent clinical data on VF in the human heart seem to suggest that human VF may have a markedly different organization. Here, we use a detailed model of the human ventricles, including a detailed description of cell electrophysiology, ventricular anatomy, and fiber direction anisotropy, to study the organization of human VF. We show that characteristics of our simulated VF are qualitatively similar to the clinical data. Furthermore, we find that human VF is driven by only approximately 10 reentrant sources and thus is much more organized than VF in animal hearts of comparable size, where VF is driven by approximately 50 sources. We investigate the influence of anisotropy ratio, tissue excitability, and restitution properties on the number of reentrant sources driving VF. We find that the number of rotors depends strongest on minimum action potential duration, a property that differs significantly between human and large animal hearts. Based on these findings, we suggest that the simpler spatial organization of human VF relative to VF in large animal hearts may be caused by differences in minimum action potential duration. Both the simpler spatial organization of human VF and its suggested cause may have important implications for treating and preventing this dangerous arrhythmia in humans. |
8,630 | The obstacles to maximising the impact of public access defibrillation: an assessment of the dispatch mechanism for out-of-hospital cardiac arrest. | To determine the diagnostic accuracy of advanced medical priority dispatch system (AMPDS) software used to dispatch public access defibrillation first responders to out-of-hospital cardiac arrests (OHCA).</AbstractText>All true OHCA events in North and West Belfast in 2004 were prospectively collated. This was achieved by a comprehensive search of all manually completed Patient Report Forms compiled by paramedics, together with autopsy reports, death certificates and medical records. The dispatch coding of all emergency calls by AMPDS software was also obtained for the same time period and region, and a comparison was made between these two datasets.</AbstractText>A single urban ambulance control centre in Northern Ireland.</AbstractText>All 238 individuals with a presumed or actual OHCA in the North and West Belfast Health and Social Services Trust population of 138 591 (2001 Census), as defined by the Utstein Criteria.</AbstractText>The accurate dispatch of an emergency ambulance to a true OHCA.</AbstractText>The sensitivity of the dispatch mechanism for detecting OHCA was 68.9% (115/167, 95% confidence interval (CI) 61.3% to 75.8%). However, the sensitivity for arrests with ventricular fibrillation (VF) was 44.4% (12/27) with sensitivity for witnessed VF of 47.1% (8/17). The positive predictive value was 63.5% (115/181, 95% CI 56.1% to 70.6%).</AbstractText>The sensitivity of this dispatch process for cardiac arrest is moderate and will constrain the effectiveness of Public Access Defibrillation (PAD) schemes which utilise it.</AbstractText>controlled-trials.com ISRCTN07286796.</AbstractText> |
8,631 | Ventricular arrhythmia discriminator programming and the impact on the incidence of inappropriate therapy in patients with implantable cardiac defibrillators. | The incidence of inappropriate therapy from implantable cardioverter defibrillators (ICDs) has been reduced by programming ventricular arrhythmia discriminators (VAD) on at the time of implant.</AbstractText>To determine which VAD is most effective in preventing inappropriate therapy.</AbstractText>Dual chamber ICD (n=48) or cardiac resynchronization therapy defibrillator (CRT-D) (n=55) implantation was performed in 103 patients (M=94, F=9). Patients were followed prospectively for therapy events (shock or anti-tachycardia pacing) for a mean 362+/-289 days. Events were correlated with clinical characteristics and VAD programming. Of the 103 pts followed, 11 received inappropriate therapy (IT), 15 received appropriate therapy (AT), and 77 received no therapy (NT). In the AT and IT groups, a total of 207 events (ATP=171, shock=36) were observed. A total of sixty-four electrograms (EGMs) were analyzed. Programming VADs "ON" versus "OFF" reduced the incidence of IT events compared to those receiving AT or NT events (p<.01), with a trend in fewer patients receiving IT (31.3% "ON" vs 55.6% "OFF", p = 0.131). Programming atrial fibrillation (AF) detection ON resulted in fewer patients receiving IT compared to those receiving AT or NT (3.6% vs 19%, p<.05). Furthermore, programming AF or AFL algorithms "ON", resulted in overall fewer episodes of IT therapy (p<.01).</AbstractText>AF or AFL discriminators significantly reduced the incidence of IT, and were predominantly responsible for the benefits from VAD programming observed in this study. Activating these features as part of routine ICD or CRT-D programming may provide a simple and effective alternative to the use of more complex and multiple VAD strategies.</AbstractText> |
8,632 | Approach to the asymptomatic patients with Brugada syndrome. | Brugada syndrome is an arrhythmogenic disease characterized by an ECG pattern of coved-type ST segment elevation in the right precordial leads and an increased risk of sudden cardiac death (SCD) as a result of polymorphic ventricular tachyarrhythmia or ventricular fibrillation (VF). Data from large patient studies and a meta-analysis of previous reports have shown that patients with a history of syncope or SCD and a spontaneous type 1 Brugada type ECG are at high risk for SCD. However, risk stratification of asymptomatic patients with Brugada type ECG is still a challenge. In particular, the use of electrophysiological study (EPS) for risk stratification remains controversial. Although some investigators have reported the possibility of use of EPS for distinguishing between high- and low-risk patients with Brugada type ECG, no precise predictor of risk for SCD in asymptomatic patients has yet been determined. The approach to treatment of these patients is thus still unclear. Large clinical prospective studies with uniform diagnostic criteria and protocols for EPS as well as extended follow-up periods of over ten years are required for prediction of SCD. |
8,633 | Improved survival associated with prophylactic implantable defibrillators in elderly patients with prior myocardial infarction and depressed ventricular function: a MADIT-II substudy. | We aim to evaluate the mortality benefit from defibrillator therapy in eligible elderly patients. Effective primary prevention of sudden cardiac death with implantable cardioverter defibrillators is well demonstrated in patients with coronary disease and depressed ventricular function.</AbstractText>Among 1,232 patients enrolled with prior infarct and left ventricular ejection fraction < or = 0.30, 204 were > or = 75 years old. Of these 204 patients, 121 underwent defibrillator implant. Relative to the younger patients, those > or = 75 years had a higher incidence of atrial fibrillation, elevated blood urea nitrogen (BUN), widened QRS, and lower use of beta-blockers and HMG-CoA reductase inhibitors. Relevant clinical covariates were similar in elderly patients randomized to conventional and defibrillator therapy. The hazard ratio for the mortality risk in patients > or = 75 years assigned to defibrillator implant compared with those in conventional therapy was 0.56 (95 confidence interval 0.29-1.08; P = 0.08) after a mean follow-up of 17.2 months. Comparatively, the hazard ratio in patients < 75 years assigned to defibrillator implant was 0.63 (0.45-0.88; P = 0.01) after 20.8 months. Elderly patients had similar reductions in quality of life (QoL) regardless of treatment randomization. Scores through Health Utilities Index Mark III (HUI) Questionnaire changes from baseline to 1 year were -0.22 for patients with conventional therapy versus -0.20 for patients with ICD, and -0.36 versus -0.27 at 2 years, respectively (P = NS).</AbstractText>The implantable defibrillator is associated with an equivalent reduction of mortality in elderly and younger patients, with no compromise in the QoL in the older age subjects.</AbstractText> |
8,634 | Fatal Loeffler's endocarditis due to hypereosinophilic syndrome. | Hypereosinophilic syndrome (HES) is a rare disorder that can manifest in various organ systems. We report the case of a 54-year-old woman with a remote history of seizure disorder who presented with early signs of right-sided heart failure. Laboratory studies showed significant eosinophilia (8 x 10(9) l(-1)). Computed tomography showed heterogeneity of the liver, mild ascites, moderate pleural effusion, multiple small pulmonary emboli, and a large right ventricular mass. Cardiac magnetic resonance imaging demonstrated that the right ventricular mass was due to thrombus and extensive endomyocardial fibrosis, consistent with Loeffler's endocarditis. Bone marrow biopsy showed marked eosinophilia but no abnormal myeloid maturation or a lymphoproliferative disorder; flow cytometry showed no clonality. Extensive infectious, immunologic, and toxicological studies were negative. Despite resolution of peripheral eosinophilia with medical management, including corticosteroids and cytotoxic agents, anticoagulation for pulmonary emboli and ventricular thrombus, and conventional treatment for heart failure, she developed worsening anasarca and died from ventricular fibrillation within 4 weeks of presentation. Autopsy confirmed the diagnosis. Loeffler's endocarditis, usually a late manifestation of HES, is characterized by fibrous thickening of the endocardium, leading to apical obliteration and restrictive cardiomyopathy, resulting in heart failure, thromboembolic events, or atrial fibrillation. HES is a potentially fatal disease with less than 50% reported 10-year survival. This case presentation is unusual in its rapidly progressive course leading to sudden death. |
8,635 | Isolated noncompaction of the left ventricular myocardium -- a review of the literature two decades after the initial case description. | Isolated noncompaction of the left ventricular myocardium (INVM), first described in 1984, is an unclassified cardiomyopathy and is assumed to occur as an arrest of the compaction process during the normal development of the heart. Between weeks 5 to 8 of human fetal development, the ventricular myocardium undergoes gradual compaction with transformation of the relatively large intertrabecular spaces into capillaries while the residual spaces within the trabecular meshwork gradually flatten or disappear. In the case of INVM, the spaces within the intertrabecular meshwork persist while no other cardiac abnormalities exist. Although there is substantial evidence supporting the developmental hypothesis, other pathogenetic processes responsible for INVM have been discussed. It can be assumed that INVM will be better understood in the future as the molecular genetic basis of cardiomyopathies will be further unravelled. Echocardiography has been shown to be the method of choice in diagnosis of INVM. The diagnostic criteria can be summarized as: 1) appearance of at least four prominent trabeculations and deep intertrabecular recesses; 2) appearance of blood flow from the ventricular cavity into the intertrabecular recesses as visualized by color Doppler imaging; 3) the segments of noncompacted myocardium mainly involve the apex and the inferior mid and lateral mid of the left ventricular wall and typically show a two-layered structure with an endsystolic ratio greater than two between the noncompacted subendocardial layer and the compacted subepicardial layer; 4) absence of coexisting cardiac abnormalities. Magnetic resonance imaging using modern gradient echo sequences has also been shown to diagnose INVM accurately. The clinical presentation of INVM is characterized by a high prevalence of heart failure, thromboembolic events and arrhythmias including ventricular tachycardia and atrial fibrillation. The establishment of a registry, which was initiated by the "Arbeitsgemeinschaft Leitende Kardiologische Krankenhausärzte (ALKK)" recently, may provide further clues for diagnosis, risk stratification, and management of this disease. |
8,636 | Post automatic implantable cardioverter defibrillator implant therapies: drugs and ablative techniques. | The aim of this article is to report the evidences about the use of drugs and ablation after implantation of a cardioverter defibrillator. Drugs can be utilized to prevent appropriate and inappropriate shocks, can influence positively or negatively defibrillation threshold, can be useful for the treatment of electrical storm. Ablation can be performed for direct cure of coexisting atrial and ventricular tachyarrhythmias or for AV node modulation. In particular, previous data demonstrate that rescue ventricular tachycardia ablation of drug-refractory electrical storm is possible by a substrate-orientated ablation approach even in patients with complex chronic infarction and various ventricular tachycardias. At the end of this article it is described how remote monitoring, a new very promising technical improvement, can be utilized for deciding, almost in real time, the use of both these therapies or for controlling their efficacy. |
8,637 | Inefficiency of renin-angiotensin inhibitors in preventing atrial fibrillation in patients with a normal heart. | Recent scientific evidence has emphasized the possible role of inhibitors of the renin-angiotensin system in preventing arrhythmic relapses in patients with paroxysmal or persistent atrial fibrillation and co-existing left ventricular hypertrophy or left ventricular dysfunction.</AbstractText>In order to verify the effects of these drugs on patients with a normal heart, we collected a series of 187 patients admitted to our division of cardiology for paroxysmal or persistent atrial fibrillation. All patients underwent cardioversion (with antiarrhythmic drugs and/or by electrical cardioversion) and were discharged in sinus rhythm. Episodes of recurrent arrhythmia were recorded during a mean follow-up period was 2 years. Patients were subdivided into 2 groups according to therapy: group 1 comprised patients receiving renin-angiotensin system inhibitors, group 2 comprised those not receiving therapy with these agents. All 91 patients in group 1 and 76 of those in group 2 had hypertension. Among the 91 patients in the group 1, 55 were treated with angiotensin-converting enzyme (ACE) inhibitors and 36 with angiotensin receptor blockers. There were no statistically significant differences in cardiovascular risk factors or antiarrhythmic drug use between the 2 groups.</AbstractText>In group 1, 83% of patients experienced <2 recurrences of atrial fibrillation during the follow-up period, while 17% had >2 episodes. In group 2, 86% of patients experienced <2 relapses during the follow-up period, while the remaining 14% had >2 relapses. There was no statistically significant difference between the 2 groups (P=0.85). A subgroup analysis showed that treatment with angiotensin receptor blockers, beta-blockers, diuretics, and calcium-channel blockers brought no advantage in sinus rhythm maintenance.</AbstractText>In our sample of hypertensive patients with a healthy heart, treatment with ACE inhibitors showed no statistically significant advantage in the prevention of atrial fibrillation relapses.</AbstractText> |
8,638 | Incidence of shock and quality of life in young patients with implantable cardioverter-defibrillator. | To analyze the incidence and causes of ICD therapies in children and young adults and verify their impact on the quality of life (QoL).</AbstractText>From March/1977 to February/2006, 29 patients (15.7+/-5.4 years old) were submitted to ICD implants. Aborted cardiac arrest (41.5%), sustained ventricular tachycardia (27.6%) and primary prophylaxis of sudden cardiac death (30.9%) indicated device therapy. The number of therapies was evaluated by interviewing patients and by ICD diagnostic data. The SF-36 questionnaire was used to measure the QoL and the results were compared to healthy population. The expectative of freedom from ICD therapies were estimated by the Kaplan-Meier method.</AbstractText>After 2.6+/-1.8 years follow-up, 8 (27.6%) patients received 141 appropriate ICD shocks due to ventricular tachycardia (6) or ventricular fibrillation (2), and 11 (37.9%) patients received 152 inappropriate ICD shocks due to supraventricular tachyarrhythmias (8) or oversensing (3). Expectative of freedom from appropriate shocks was 74.2+/-9.0% and 66.7+/-10.7% after one and three years, respectively. Compared to healthy population, QoL decreased in physical function (61.7+/-28.7), vitality (64.7+/-19.1), mental health (65.9+/-22.7) and role-emotional domains (66.7+/-38.5). All patients referred fear and concern related to ICD use.</AbstractText>Despite the efficacy of ICD therapies, the high incidence of appropriate and inappropriate shocks interfered in patients QoL and adaptation to the device.</AbstractText> |
8,639 | The impact of patient-prosthesis mismatch on late outcomes after mitral valve replacement. | The incidence of patient-prosthesis mismatch after mitral valve replacement and its effect on late outcomes have remained unclear. This study was conducted to determine the impact of patient-prosthesis mismatch on recurrent congestive heart failure, postoperative pulmonary hypertension, and late survival after mitral valve replacement.</AbstractText>Between 1985 and 2005, 884 patients, with a mean age 63 +/- 12 years, underwent mitral valve replacement (657 mechanical, 227 bioprosthesis) with contemporary prostheses. Mean clinical and echocardiographic follow-up was 5.1 +/- 4.1 years (4344 patient-years). Patient-prosthesis mismatch was defined as an indexed effective orifice area of 1.25 cm2/m2 or less. Parametric and nonparametric analyses were used to determine predictors of outcomes.</AbstractText>The incidence of patient-prosthesis mismatch was 32%. Predictors of recurrent congestive heart failure included low indexed effective orifice area, low ejection fraction, elevated postoperative mean mitral gradient, and use of a bioprosthesis (P < or = .05). Postoperative pulmonary hypertension was associated with small mitral size, elevated mean mitral gradient, low ejection fraction, and atrial fibrillation (P < or = .05); indexed effective orifice area did not predict postoperative pulmonary hypertension (P = .89). Poor late survival was predicted by low indexed effective orifice area (< or =1.25 cm2/m2), New York Heart Association class 3 or 4, elevated right ventricular pressure, stroke, older age, coronary artery disease, and bioprosthesis use (P < or = .05). Survival for patients with patient-prosthesis mismatch versus those without patient-prosthesis mismatch at 1, 3, 5, and 10 years was 91% versus 95%, 85% versus 90%, 78% versus 86%, and 65% versus 75%, respectively (P = .05).</AbstractText>Patient-prosthesis mismatch after mitral valve replacement is not uncommon; it is associated with recurrence of congestive heart failure and postoperative pulmonary hypertension and independently affected late survival. This study emphasizes the importance of implanting a sufficiently large prosthesis in adult patients undergoing mitral valve replacement.</AbstractText> |
8,640 | Characteristics of congestive heart failure accompanied by atrial fibrillation with special reference to tachycardia-induced cardiomyopathy. | Sustained tachycardia causes left ventricular (LV) systolic dysfunction leading to heart failure (HF), which is widely known as "tachycardia-induced cardiomyopathy (TIC)", but its prevalence and prognosis in Japanese remain unclear.</AbstractText>Of 213 consecutive patients with HF associated with atrial fibrillation (AF) requiring hospitalization (n=213) between January 1999 and December 2004, and 104 (83 males, 67+/-12.6 years) were identified as not having any structural heart disease. Of them 41 (39%) had a normal LV ejection fraction (LVEF) at the initial admission, and the remaining patients fell into 2 groups: those with rapid (<6 months) normalization of the LVEF after AF management (presumed TIC, 30 patients, 29%) and those with persistent LV systolic dysfunction (dilated cardiomyopathy (DCM), 33 patients, 32%). Although the B-type natriuretic peptide value and LVEF did not differ between the 2 groups, the LV size on admission was significantly smaller in the TIC group (LV end-diastolic dimension (LVDd) 57.6+/-7.2, LV end-systolic dimension (LVDs) 49.4+/-8.0) than in the DCM group (LVDd 63.4 +/-8.8, LVDs 55.3+/-9.6, p<0.05). During a follow-up period of 42.1+/-21.2 months, cardiac death and recurrent HF hospitalization were significantly less frequent in the TIC group than in the DCM group.</AbstractText>In AF-associated HF requiring hospitalization, TIC is the presumed cause in approximately one-third of patients without any previously known structural heart disease. That particular group is characterized by a relatively smaller LV and better prognosis under medical treatment.</AbstractText> |
8,641 | Inappropriate interventions during the long-term follow-up of patients with an implantable defibrillator. | In patients with an implantable defibrillator (ICD), inappropriate ICD interventions alter the quality of life, may cause hospitalisations and limit cost-effectiveness. The aim of the study was to determine the incidence and causes of inappropriate ICD interventions, and to identify patients at risk.</AbstractText>For this observational longitudinal study, consecutive patients undergoing ICD implantation at the University Hospital of Berne were included in a registry. All stored electrograms of episodes triggering ICD interventions were systematically reviewed and analysed to determine whether ICD interventions were appropriate or inappropriate. Inappropriate ICD interventions were classified according to their cause, and risk factors were sought.</AbstractText>214 consecutive patients were followed during a median time of 2.7 years (3.7 years IQR, 698 patient years). 81 inappropriate ICD interventions occurred in 58 patients (27%). Factors triggering inappropriate ICD interventions included atrial fibrillation and flutter (n = 35, 44%), sinus tachycardia (n = 26, 32%), lead fracture (n = 12), recurrent self-terminating ventricular tachycardia (n = 5), double-counting due to T-wave oversensing (n = 3). The only identifiable risk factor for inappropriate ICD interventions was sustained ventricular tachycardia as index arrhythmia.</AbstractText>An important proportion of ICD patients suffer inappropriate ICD interventions that are most commonly due to supraventricular arrhythmias. Patients with ventricular tachycardia prior to ICD implantation are at higher risk of inappropriate ICD interventions. Interventions aiming at decreasing the risk of inappropriate ICD interventions should be considered in these patients.</AbstractText> |
8,642 | [Transapical approach for aortic stented valve implantation: experimental results]. | Percutaneous aortic valve replacement has been performed in humans mainly for non-surgical candidates. We evaluated on animals a transapical approach to deliver an aortic stented valve without cardiopulmonary bypass.</AbstractText>A tubular pericardial valve fixed within a cobalt-nickel stent (Medtronic, Inc.) was implanted using a transapical approach in five adult sheep. A left thoracotomy was used to access the apex of the heart. The crimped valve was deployed in orthotopic position with a valvuloplasty balloon catheter on the beating heart after decreasing the left ventricular pressure by using either drugs or inferior vena cava occlusion. Deployments were performed under fluoroscopy and epicardial 2D Doppler echocardiography. Exact positioning of the valve into the target area was confirmed by autopsy at the end of the procedures.</AbstractText>Valves were unsuccessfully deployed at the target site in all cases but one. Three valves were implanted in a supra-annular position with two of them in supracoronary position. One valve was implanted below the native annulus in the outflow tract. Valvular leak was noted in all but one implants. Coronary obstruction occurred twice and early valve retrograde migration once. Ventricular fibrillation or diastolic cardiac arrest occurred less than 20 minutes after stent deployment in all cases.</AbstractText>In our experience the transapical approach does not facilitate delivery of a stented valve. Despite its technically feasibility, advanced stent design and improvements in delivery system are required before to continue experimental studies in transapical approach for aortic stented valve.</AbstractText> |
8,643 | [Long QT syndrome induced by cordaron and quinidine]. | The article presents an observation of a 63-year-old female patient suffering from arterial hypertension, coronary artery disease complicated by a persistent form of atrial fibrillation during 1.5 months, and hereditary Minkowski-Chauffard hemolytic anemia. Treatment with cordaron proved to be ineffective, while oral administration of quinidin in a dose of 1 gr (0.2 gr five times a day) led to restoration of sinus rhythm. However, long QT interval syndrome complicated by ventricular tachycardic paroxysms of torsade de pointes type developed; later it transformed into ventricular fibrillation. |
8,644 | Syncope in hypertrophic cardiomyopathy: mechanisms and consequences for treatment. | Hypertrophic cardiomyopathy (HCM) is an inherited disease with marked phenotypic variability that includes the extent of hypertrophy, the presence and severity of symptoms, and the natural history of the disease. Symptoms of impaired consciousness (syncope and pre-syncope) occur in approximately 15-25% of patients with hypertrophic cardiomyopathy (HCM). In young patients a history of recurrent syncope is associated with an increased risk of sudden death. Detailed investigations identify a probable mechanism in a minority of these, usually paroxysmal atrial fibrillation or ventricular tachycardia. In the majority, however, no likely mechanism is found despite extensive investigation. Although this may be the case, it is still of vital importance to exclude potentially treatable causes of syncope. |
8,645 | Atrial fibrillation and congestive heart failure: a two-way street. | Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia encountered in clinical cardiology, particularly in patients with heart failure. Its prevalence increases with the degree of left ventricular dysfunction and severity of heart failure symptoms. The development of AF in the setting of heart failure has been shown to result in increased mortality. Studies thus far indicate that rhythm control with antiarrhythmic drug therapy or catheter ablation offers both symptomatic and probably survival advantage in patients with heart failure and AF. In patients with permanent AF, the effects of restoring a regular ventricular response with atrioventricular junction ablation followed by biventricular pacing remain to be shown. In the current manuscript, we will review the proposed mechanisms of increased morbidity and mortality associated with AF and the current treatment options including the roles of radiofrequency ablation and pacing. |
8,646 | Tako-tsubo cardiomyopathy complicating left atrial radiofrequency ablation. | Two female patients undergoing left atrial radiofrequency catheter ablation developed Tako-tsubo cardiomyopathy. This reversible form of left ventricular dysfunction is known to occur under conditions associated with marked sympathetic nervous activation. Radiofrequency catheter ablation in the left atrium can damage autonomic ganglionated plexi, leading to vagal withdrawal, thus resulting in enhanced sympathetic tone. Tako-tsubo cardiomyopathy has not been previously described following radiofrequency catheter ablation. |
8,647 | Reduction of dispersion of repolarization and prolongation of postrepolarization refractoriness explain the antiarrhythmic effects of quinidine in a model of short QT syndrome. | Short QT syndrome (SQTS) is a newly described ion channelopathy, characterized by a short QT interval resulting from an accelerated cardiac repolarization, associated with syncope, atrial fibrillation, and sudden cardiac death due to ventricular fibrillation. As therapeutic options in SQTS are still controversial, we examined antiarrhythmic mechanisms in an experimental model of SQTS.</AbstractText>Pinacidil, an I(K-ATP) channel opener, was administered in increasing concentrations (50-100 microM) in 48 Langendorff-perfused rabbit hearts and led to a significant reduction of action potential duration and QT interval, thereby mimicking SQTS. Eight simultaneously recorded monophasic action potentials demonstrated an increase in dispersion of repolarization, especially between the left and the right ventricle. During programmed ventricular stimulation with up to two extrastimuli, pinacidil significantly increased the inducibility of ventricular fibrillation (1 heart under baseline conditions, 29 hearts during pinacidil administration; P = 0.0001). Additional treatment with the I(Kr) blocker sotalol (100 microM) and the class I antiarrhythmic drugs flecainide (2 microM) and quinidine (0.5 microM) randomly assigned to three groups of 16 hearts led to prolongation of repolarization as well as refractory period. Sotalol or flecainide did not reduce the rate of inducibility of ventricular fibrillation significantly (P = 0.63; P = 0.219). However, quinidine reduced the inducibility of ventricular fibrillation by 73% (P = 0.008). The antiarrhythmic potential of quinidine was associated with a significantly greater prolongation of MAP duration, refractoriness, and postrepolarization refractoriness (PRR) as compared with sotalol and flecainide. Moreover, quinidine, in contrast to sotalol and flecainide, reduced dispersion of repolarization.</AbstractText>Pinacidil mimics SQTS via increasing potassium outward currents, thereby facilitating inducibility of ventricular fibrillation. Quinidine demonstrates superior antiarrhythmic properties in the treatment of ventricular fibrillation in this model as compared with sotalol and flecainide because of its effects on refractoriness, PRR, and by reducing dispersion of repolarization.</AbstractText> |
8,648 | Anionic currents in hypoxia-mediated cardiac toxicity: a computer study. | Hypoxia-caused modulation of cardiac electrophysiology was modeled by computer simulation. Emphasis was on the effect of activation of anionic channels on the electrical state of the tissue. The model includes implicitly the effect of the presence of reactive oxygen species (ROS) and nitrogen oxide (NO) on myocyte membrane voltage by their contribution to the activation of chloride currents. Three anionic currents were added to the modified Luo-Rudy ionic model of the ventricular action potential used in these calculations. The effect of the activation of the usually dormant currents due to hypoxia results in the modulation of the morphology of the action potential and the ECG. Transition of the ECG to ventricular fibrillation is shown. An important finding reported here is that control of the swelling and protein kinase C (PKC)-activated chloride currents can limit the electrical chaos of pharmacologically-caused hypoxic cardiac toxicity. |
8,649 | [Successful use of an AED following anterior myocardial infarction]. | A participant of the annual Hamburg marathon collapses on the finish line. Medics at the scene find a conscious patient and prepare transport to the finish area medical center. During transport the patient becomes unconscious and pulseless. The medics immediately perform basic life support and cardiopulmonary resuscitation (CPR). An automated external defibrillator (AED) is attached and after analysis of the patient}s heart rhythm the patient is defibrillated twice. The ambulance service reach the scene with a delay. The emergency physician}s ECG shows ventricular fibrillation (VF) and two more defibrillations are delivered. Return of spontaneous circulation can be achieved. After stabilisation the patient is taken to hospital by ambulance. The ECG shows an anterior myocardial infarction and right bundle-branch block. The coronary angioplasty (PTCA) shows single-vessel disease with complete stenosis of the proximal part of the anterior interventricular branch. Revasucarisation is successful and a coronary stent is applied. The patient survives neurologically intact. This case report demonstrates the importance of readily available AED and specially trained medics. By immediately using the AED this patient was defibrillated before the ambulance service and emergency physician arrived at the scene. Spontaneous circulation was restored. |
8,650 | Determinants of plasma levels of brain natriuretic peptide after acute ischemic stroke or TIA. | Plasma levels of brain natriuretic peptide (BNP) are frequently elevated after an acute stroke and have been shown to be an independent predictor of mortality. However, the relationships between stroke and BNP concentrations have not yet been systematically investigated. Plasma BNP assay and echocardiography were performed in 48 patients with ischemic stroke or TIA with a mean delay of 12.7 h after onset. Median BNP concentration was 88.6 pg/mL (range 5-1270). Older age, chronic heart failure, atrial fibrillation, stroke severity, lower hemoglobin levels, lower left ventricular ejection fraction, and abnormalities of left atrium or appendage (LA/LAA) were univariately associated with increased BNP levels. At multivariable analysis, the presence of at least one LA/LAA abnormality (atrial dilatation, low flow velocity, spontaneous echocontrast or thrombus) had the strongest association with BNP, explaining 38.9% of the variance in the whole sample and 28.5% in patients without atrial fibrillation. In acute ischemic stroke patients, elevated plasma BNP levels have multiple determinants, among which left atrial disease appears to be the stronger, even in patients without atrial fibrillation. These results encourage further investigation of plasma BNP concentration as a potential marker of the presence of left atrial sources of emboli. |
8,651 | Prediction of atrial fibrillation in patients with cardiac dysfunctions: P wave signal-averaged ECG and chemoreflexsensitivity in atrial fibrillation. | Atrial fibrillation (AF) is a common arrhythmia in advanced heart failure. The occurrence of AF increases the risk of death and hospitalization for patients with heart failure. The results of different studies indicated that patients with paroxysmal AF have a longer filtered P wave duration (FPD), a lower root mean square voltage of the last 20 ms of the P wave (RMS 20), and a lower chemoreflexsensitivity (CHRS). Our study bases on these observations in order to examine the methods for predicting AF in patients with a left ventricular ejection fraction below 40% without a prior documentation of AF.</AbstractText>The ratio between the difference of RR intervals in ECG and venous pO(2) before and after 5-min oxygen inhalation was measured (ms/mmHg) in order to determine the CHRS. A P wave signal-averaged ECG was performed for the measurement of FPD and RMS 20. The measurements were only performed in 94 patients with sinus rhythm. AF occurred during the mean follow-up of 39.9 months in 24 patients (26%). There were no significant differences concerning age, heart diseases, sex, ejection fraction, heart rate, or the use of drugs. The FPD (130.3 +/- 4.2 vs. 118.9 +/- 12.4 ms, P < 0.0001) was significantly longer and the RMS 20 (3.03 +/- 0.95 vs. 3.83 +/- 1.58 microV, P = 0.02) was significantly lower in patients with AF than in sinus rhythm. The CHRS did not differ significantly between both groups (3.57 +/- 1.49 vs. 3.48 +/- 1.62 ms/mmHg, P = 0.81). The chi(2) test showed that the threshold of FPD>or=125 ms and RMS 20 <or=3.3 microV revealed the best predictive value for AF. A stepwise logistic regression analysis of all variables identified the threshold of FPD>or=125 ms and RMS 20 <or=3.3 microV (OR 18.71; 95% CI, 4.85-72.16, P < 0.0001) as independent predictors for AF.</AbstractText>In summary, our data show that the results of a P wave signal-averaged ECG can predict the risk for new onset of AF in patients with heart failure. The value of signal-averaged FPD is probably the result of reflecting the intra-atrial conduction delay, which is a pathophysiological condition for AF. The CHRS is not a suitable method for predicting AF.</AbstractText> |
8,652 | Catheter ablation of premature ventricular contractions originating from the His bundle region. | We describe a 35-year-old man with idiopathic frequent premature ventricular contractions (PVCs) originating from the His-bundle region, where a low frequency ventricular potential was recorded in the bipolar recording and QR pattern in the unipolar recording. Electro-anatomical mapping revealed a confined low voltage zone (<1.2 mV) in the His-bundle region, and the activation spread out radially to the entire right ventricle. The PVCs were successfully abolished without any atrioventricular block by a step-wise incremental radiofrequency energy application to the His-bundle region. The patient has remained free from PVCs or any symptoms without medication during a 23 month follow-up period. |
8,653 | Ventricular rate smoothing for atrial fibrillation: a quantitative comparison study. | To quantitatively compare the ventricular rate-smoothing (VRS) effects of different ventricular pacing (VP) protocols for atrial fibrillation (AF).</AbstractText>Using a recently developed open-source model that can simulate the ventricular response in AF and VP, the performance of fixed-rate pacing and four previously published VRS algorithms were assessed by the mean RR (mRR), the root mean square of successive RR differences (RMSSD), the percentage of ventricular senses (VS%), and the percentage of short RR intervals (sRR%). All pacing protocols cause rate-dependent reduction of RMSSD, VS%, and sRR% with or without shortening of mRR compared to spontaneous AF. Fixed-rate pacing was more sensitive to the intrinsic rate than the VRS algorithms. The performance was generally comparable between different VRS algorithms, although higher mRR and VS% can be achieved at the expense of larger RMSSD and sRR%.</AbstractText>The effect of VP on ventricular rhythm in AF depends on both intrinsic rate and the aggressiveness of the pacing protocol. Adequate rate control is necessary for effective operation of the VRS algorithm. Choosing VRS algorithm should balance between the beneficial effects of rate regularization and the negative effects of increasing heart rate and percentage of VP.</AbstractText> |
8,654 | Prevalence and prognostic impact of comorbidities in heart failure patients with implantable cardioverter defibrillator. | This study assessed the prevalence and the prognostic impact of comorbidities in heart failure patients with implantatable cardioverter-defibrillator (ICD).</AbstractText>We prospectively enrolled 146 patients with chronic heart failure, an ICD, and systolic dysfunction (mean ejection fraction 29 +/- 10%). Cardiac death was chosen as the primary endpoint. Death or appropriate ICD therapy, i.e. antitachycardia pacing/shock due to sustained ventricular tachycardia or ventricular fibrillation, was chosen as the secondary endpoint. Seventy-five patients (52%) had chronic kidney disease (defined as an estimated glomerular filtration rate <60 mL/min/1.73 m(2)), 39 patients (27%) were anaemic, and 34 patients (23%) had diabetes mellitus. During a follow-up of 663 +/- 400 days, 22 patients (15%) died, and 41 patients (28%) received an appropriate ICD therapy. By multivariate Cox analysis, independent predictors of cardiac death were chronic kidney disease, age, and NYHA functional class. Death/appropriate ICD therapy were independently predicted by chronic kidney disease and QRS duration. In the presence of chronic kidney disease, outcome was significantly worse when compared with the absence (event-free survival rate 51 vs. 76%, P < 0.001).</AbstractText>In heart failure patients with an ICD, comorbidities are frequent but only the presence of chronic kidney disease is independently associated with increased morbidity and mortality.</AbstractText> |
8,655 | Abrupt changes in FKBP12.6 and SERCA2a expression contribute to sudden occurrence of ventricular fibrillation on reperfusion and are prevented by CPU86017. | The occurrence of ventricular fibrillation (VF) is dependent on the deterioration of channelopathy in the myocardium. It is interesting to investigate molecular changes in relation to abrupt appearance of VF on reperfusion. We aimed to study whether changes in the expression of FKBP12.6 and SERCA2a and the endothelin (ET) system on reperfusion against ischemia were related to the rapid occurrence of VF and whether CPU86017, a class III antiarrhythmic agent which blocks I(Kr), I(Ks), and I(Ca.L), suppressed VF by correcting the molecular changes on reperfusion.</AbstractText>Cardiomyopathy (CM) was produced by 0.4 mg/kg sc L-thyroxin for 10 d in rats, and subjected to 10 min coronary artery ligation/reperfusion on d 11. Expressions of the Ca2+ handling and ET system and calcium transients were conducted and CPU86017 was injected (4 mg/kg, sc) on d 6-10.</AbstractText>A high incidence of VF was found on reperfusion of the rat CM hearts, but there was no VF before reperfusion. The elevation of diastolic calcium was significant in the CM myocytes and exhibited abnormality of the Ca2+ handling system. The rapid downregulation of mRNA and the protein expression of FKBP12.6 and SERCA2a were found on reperfusion in association with the upregulation of the expression of the endothelin-converting enzyme (ECE) and protein kinase A (PKA), in contrast, no change in the ryanodine type 2 receptor (RyR2), phospholamban (PLB), endothelin A receptor (ETAR), and iNOS was found. CPU86017 removed these changes and suppressed VF.</AbstractText>Abrupt changes in the expression of FKBP12.6, SERCA2a, PKA, and ECE on reperfusion against ischemia, which are responsible for the rapid occurrence of VF, have been observed. These changes are effectively prevented by CPU86017.</AbstractText> |
8,656 | [Evaluation of atrial function by echocardiography]. | In cardiology, ventricular function has extensively been studied, whereas atrial function received less attention. For such a reason atrial function is less known. The aim of this review was to summarize the role of atrial function and to explain how echocardiography and new echocardiographic-derived techniques may be of help to better study atrial function. |
8,657 | [Permanent atrial fibrillation and heart failure: radiofrequency ablation of atrioventricular junction and cardiac resynchronization therapy: review of the literature and of the new techniques for echocardiographic assessment]. | Radiofrequency ablation of atrioventricular junction plus pacing therapy ("ablate and pace") is an effective non-pharmacological therapy in patients with medically refractory permanent atrial fibrillation and heart failure. However, the chronic right ventricular pacing may result in regional wall motion abnormalities and adverse hemodynamic effects. These findings imply that patients with permanent atrial fibrillation who undergo "ablate and pace" may benefit from cardiac resynchronization therapy. The review of both observational and randomized studies suggests an important role of biventricular pacing combined with atrioventricular junction ablation only in patients with severe reduction of left ventricular ejection fraction and advanced heart failure. In all other patients with permanent atrial fibrillation, the comparison of conventional right ventricular pacing with respect to cardiac resynchronization therapy showed conflicting results. The assessment of cardiac dyssynchrony by means of new echocardiographic technology, including three-dimensional analysis, may improve the selection of the best pacing modality in patients undergoing "ablate and pace" for drug refractory permanent atrial fibrillation. |
8,658 | A PET study of regional cerebral blood flow after experimental cardiopulmonary resuscitation. | Cerebral blood flow (CBF) during cardiopulmonary resuscitation and after restoration of spontaneous circulation (ROSC) from cardiac arrest has previously been measured with the microspheres and laser Doppler techniques. We used positron emission tomography (PET) with [15O]--water to map the haemodynamic changes after ROSC in nine young pigs. After the baseline PET recording, ventricular fibrillation of 5 min duration was induced, followed by closed-chest cardiopulmonary resuscitation (CPR) in conjunction with IV administration of three bolus doses of adrenaline (epinephrine). After CPR, external defibrillatory shocks were applied to achieve ROSC. CBF was measured at intervals during 4h after ROSC. Relative to the mean global CBF at baseline (32+/-5 ml hg(-1)min(-1)), there was a substantial global increase in CBF at 10 min, especially in the diencephalon. This was followed by an interval of cortical hypoperfusion and a subsequent gradual return to baseline values. |
8,659 | Comparison of the efficacy of metoprolol and carvedilol for preventing atrial fibrillation after coronary bypass surgery. | Atrial fibrillation (AF) occurs frequently after coronary artery bypass grafting (CABG) and often results in prolonged postsurgical hospital stays and increased mortality and morbidity. Beta blockers are known to prevent postoperative AF. In this prospective study, we investigated the efficacy of carvedilol compared with metoprolol succinate in preventing postoperative AF.</AbstractText>Subjects included 110 patients (31 women, 79 men; mean age, 60+/-10 years, range, 39-82 years) who had undergone CABG. Patients were randomized to receive either metoprolol or carvedilol, and all patients received the drugs 3 days prior to surgery. Metoprolol was started at 50 mg twice daily and carvedilol was started at 12.5 mg twice daily. The doses were titrated according to the patients' hemodynamic responses. All patients were monitored for 3 days after the surgery.</AbstractText>Of the 110 patients, 55 (50%) were treated with metoprolol succinate, and 55 (50%) were treated with carvedilol. Baseline characteristics and operative data of the patients did not differ between groups. During follow-up, 20 patients (36%) in the metoprolol group and 9 patients (16%) in the carvedilol group developed AF (P=0.029). Multiple stepwise logistic regression analysis showed that metoprolol use, older age, and impaired left ventricular ejection fraction were independent risk factors for developing AF, and carvedilol use was found to be independently related to sinus rhythm maintenance after CABG (P=0.02).</AbstractText>These results show that carvedilol is superior to metoprolol in decreasing development of early postoperative AF.</AbstractText> |
8,660 | Broad complex atrial fibrillation. | The management of broad complex atrial fibrillation is complex and may be a source of morbidity and mortality if not correctly recognized and treated appropriately. We present a case series of 3 patients who were managed in our emergency department after complaints of palpitations. They presented with varying forms of rapid atrial fibrillation that had broad complexes on the 12-lead electrocardiogram. The first 2 patients were treated with calcium channel blockers for rate control, and treatment was complicated by rapid arrhythmia that required cardioversion. The final patient was correctly treated with intravenous procainamide. The diagnosis of Wolff-Parkinson-White syndrome was eventually made in all these patients. Broad complex atrial fibrillation must be treated with respect. Cases with rapid ventricular rate can decompensate from mismanagement due to poor ability to recognize the possibility of Wolff-Parkinson-White syndrome in such patients. Procainamide forms the cornerstone of treatment in hemodynamically stable rapid broad complex atrial fibrillation of unknown origin. |
8,661 | External cardiac defibrillation during wet-surface cooling in pigs. | During surface cooling with ice-cold water, safety and effectiveness of transthoracic defibrillation was assessed.</AbstractText>In a pig ventricular fibrillation cardiac arrest model, once (n = 6), defibrillation was done first in a dry and then in a wet condition using the ThermoSuit System (Life Recovery Systems, HD, LLC, Kinnelon, NJ), which circulates a thin layer of ice-cold water (approximately 4 degrees C) over the skin surface. Another time (n = 6), defibrillation was done first in a wet and then in a dry condition. Success of defibrillation was defined as restoration of spontaneous circulation, and the current and voltage of the defibrillation signal was measured.</AbstractText>There was a tendency toward less number of shocks needed for achieving restoration of spontaneous circulation in the wet condition as compared with the number of shocks needed in the dry condition. The energy delivered in both dry and wet conditions was 144 +/- 3 J.</AbstractText>Transthoracic defibrillation is safe and effective in a wet condition after cooling with ice-cold water.</AbstractText> |
8,662 | Prevalence and predictors of arrhythmia in end stage renal disease patients on hemodialysis. | Sudden death is common in end-stage renal disease (ESRD). Cardiac arrhythmia is observed frequently in patients with ESRD and is thought to be responsible for this high rate of sudden death. This study investigated the prevalence and the predictors of arrhythmia in patients on maintenance dialysis.</AbstractText>Ninety-four patients on hemodialysis program were enrolled in the study. Routine laboratory results were noted. Arrhythmia, periods of silent ischemia, and heart-rate variability analyses were obtained from 24-hour Holter monitor recordings. Corrected QT (QTc) dispersion was calculated from 12-lead surface EKG. Echocardiographic and tissue Doppler examinations were performed on interdialytic days as well. Ventricular arrhythmia was classified according to Lown classification; classes 3 and above were accepted as complex ventricular arrhythmia (CVA).</AbstractText>The mean age was 52.5+/-13.2 years; 44 (46.8%) were women. Ventricular premature contractions were detected in 80 (85.1%) patients, of whom 35 (37.2%) were classified as complex ventricular arrhythmia (CVA). Coronary artery disease, hypertension, and QTc dispersion appeared as independent factors predictive of CVA development. Atrial premature contractions (APC) were detected in 53 patients (56.4%) and supraventricular arrhythmia in 15 (16%) patients; all were identified as atrial fibrillation. Duration of dialysis therapy was found as an independent predictor of APC.</AbstractText>Arrhythmia is frequently observed in ESRD patients receiving hemodialysis and may be responsible for the high rate of sudden mortality. Hypertension, CAD, and QTc dispersion are independent predictors of CVA, and duration of dialysis therapy is an independent factor affecting APC development in these patients.</AbstractText> |
8,663 | Idiopathic ventricular fibrillation. | Idiopathic ventricular fibrillation (IVF) is responsible for a sizable part of sudden cardiac death (SCD). Furthermore, it has a high recurrence rate. Recent publications have shown that IVF is often caused by premature ventricular contractions (PVCs) arising from the right ventricular outflow tract (RVOT) or the Purkinje system. Some cases are associated with unbalanced sympathetic cardiac innervation. Some other cases are now believed to be a variant of the Brugada syndrome. Drugs have been shown to be ineffective in the therapy of IVF. The implantable cardioverter defibrillator used to be the only effective therapeutic option. However, radiofrequency (RF) catheter ablation of the trigger (PVCs arising from the RVOT or Purkinje system) has shown to be effective in a considerable number of patients and is now included in the guidelines of secondary prevention of SCD. |
8,664 | [Short QT syndrome]. | Short QT syndrome is a new genetic disorder associated with familial atrial fibrillation and/or sudden death or syncope. To date, different mutations in genes encoding for cardiac ion channels (KCNH2, KCNQ1, and KCNJ2) have been identified to cause the short QT syndrome. The mutations lead to a gain of function of the affected current (IKr, IKs, and IK1). The phenotype is characterized by a shortened QT interval<335 ms after correction for heart rate at rates<80 beats/min. Furthermore, the QT interval poorly adapts to heart rate. Patients exhibit shortened atrial and ventricular effective refractory periods and, in the majority, inducibility of ventricular fibrillation. Death occurs already in newborns. Therapy of choice seems to be the implantable cardioverter defibrillator because of the high incidence of sudden death. Pharmacological treatment has been studied and it could be demonstrated, that some mutant currents may be insufficiently suppressed by drugs targeted to block the specific current such as, e.g., sotalol or ibutilide in patients with a mutation in the IKr-coding gene KCNH2 (HERG). Quinidine proved to be efficient in prolonging the QT interval and normalizing the effective refractory periods in some patients. |
8,665 | Adherence to resuscitation guidelines during prehospital care of cardiac arrest patients. | The impact of prehospital care after the return of spontaneous circulation in out-of-hospital cardiac arrest patients is not known. This study describes adherence to the resuscitation guidelines, factors associated with poor adherence and possible impact of prehospital postresuscitation care on the outcome of out-of-hospital cardiac arrest.</AbstractText>One hundred and fifty-seven Finnish out-of-hospital cardiac arrest patients hospitalized during 1 year, were analyzed retrospectively. Patient and arrest characteristics, prehospital postresuscitation care and survival to hospital discharge were analyzed using multivariate logistic regression.</AbstractText>Forty percent of the patients received care accordant with the guidelines. Male sex (P=0.045), witnessed arrest (P=0.031), initial ventricular fibrillation/ventricular tachycardia rhythm (P=0.007) and the presence of an emergency physician (P=0.017) were associated with care in line with the current guidelines. In multivariate logistic regression analysis, age over median (odds ratio=3.6, 95% confidence interval 1.5-8.6), nonventricular fibrillation/ventricular tachycardia initial rhythm (odds ratio=4.0, 95% confidence interval 1.6-9.8), administration of adrenaline (odds ratio=7.0, 95% confidence interval 2.3-21.4) and unsatisfactory prehospital postresuscitation care (odds ratio=2.5, 95% confidence interval 1.1-6.3) were associated with a failure to survive up to hospital discharge.</AbstractText>Less than 50% of out-of-hospital cardiac arrest patients received prehospital postresuscitation care compatible with the current guidelines. Markers of poor prognosis were associated with unsatisfactory care, which in turn was more frequent among the patients who did not survive to hospital discharge. The importance of the guidelines should be highlighted in the future.</AbstractText> |
8,666 | Simultaneous onset of hemorrhagic and ischemic strokes. | Primary brain hemorrhage and infarction only very rarely occur simultaneously. We report a patient with the simultaneous onset of hemorrhagic and ischemic strokes who had uncontrolled hypertension and atrial fibrillation. Neuroradiologic investigations revealed a large right thalamic hematoma with ventricular extension and an infarct in the territory of the left internal carotid artery. The patient died at the end of the second day because of herniation in spite of anti-edema and antihypertensive medication. |
8,667 | Trauma associated with cardiac dysrhythmias: results from a large matched case-control study. | Various cardiac dysrhythmias such as supraventricular and ventricular premature beats, supraventricular and ventricular paroxysmal tachycardia, atrial and ventricular fibrillation and atrial flutter have been reported in case series, as complications of blunt cardiac and thoracic trauma. The objective of this research was to determine whether thoracic or blunt cardiac injury is associated with cardiac dysrhythmia in a large multistate hospitalized population.</AbstractText>Cases and matched (by age) controls were identified based on hospital discharge information that was collected from 986 acute general hospitals across 33 states in 2001. Both the exposure (thoracic trauma and blunt cardiac injury) and the outcome (cardiac dysrhythmias) were identified based on ICD-9-CM discharge diagnoses. Unadjusted and conditional adjusted (for gender, race, length of stay, and primary source of payment) multivariate logistic regression analyses were performed.</AbstractText>After adjusting for potential confounders, patients 50 years and younger diagnosed with blunt cardiac injury had a fourfold (95% confidence interval, 1.40-11.60) increase in the risk of cardiac dysrhythmia. Independent of potential confounding factors, discharge for blunt cardiac injury among patients 51 to 70 years old was associated with a twofold (95% confidence interval, 1.36-3.82) increased risk for cardiac dysrhythmia.</AbstractText>Blunt cardiac injury was found to be a significant risk factor for cardiac dysrhythmia. Longitudinal studies are needed to better establish the association between trauma and cardiac dysrhythmias.</AbstractText> |
8,668 | A neurobiological basis for ELF guidelines. | It is well understood that electric currents applied directly to the body can stimulate peripheral nerve and muscle tissue; such effects can be fatal if breathing is inhibited or ventricular fibrillation is induced. Exposure to extremely low frequency electric and magnetic fields will also induce electric fields and currents within the body, but these are almost always much lower than those that can stimulate peripheral nerve tissue. Guidance on exposure to such fields is based on the avoidance of acute effects in the central nervous system. This paper reviews the physiological processes involved in nerve cell excitability in the peripheral and central nervous system, and the experimental evidence for physiologically weak electric field effects. It is concluded that the integrative properties of the synapses and neural networks of the central nervous system render cognitive function sensitive to the effects of physiologically weak electric fields, below the threshold for peripheral nerve stimulation. However, the only direct evidence of these weak field interactions within the central nervous system is the induction of phosphenes in humans--the perception of faint flickering light in the periphery of the visual field, by magnetic field exposure. Other tissues are potentially sensitive to induced electric fields through effects on voltage-gated ion channels, but the sensitivity of these ion channels is likely to be lower than those of nerve and muscle cells specialized for rapid electrical signaling. In addition, such tissues lack the integrative properties of synapses and neuronal networks that render the central nervous system potentially more vulnerable. |
8,669 | Effects of rotigaptide, a gap junction modifier, on defibrillation energy and resuscitation from cardiac arrest in rabbits. | The gap junction modifier Rotigaptide (ZP123), which promotes cellular coupling, was hypothesized to decrease defibrillation thresholds during prolonged ventricular fibrillation (VF). Thirty-two New Zealand white rabbits were randomized to receive saline (control, n = 16) or Rotigaptide (n = 16). Following 4 min of untreated VF, biphasic defibrillation shocks were applied through chest wall patches, starting either at 300 volts (V) (n = 16) or 500 V (n = 16), with 200 V increasing steps to 900 V in case of shock failure. Rotigaptide significantly decreased defibrillation voltage requirements (average cumulative voltage of all shocks: 1206 +/- 709 V in control group vs. 844 +/- 546 V in treated group, P = .002). Rotigaptide had no effect on heart rate, QRS duration, QT interval, ventricular effective refractory period, monophasic action potential duration or on connexin 43 density using immunofluorescence. Rotigaptide improves the ability to defibrillate after untreated VF. |
8,670 | Observations on the safety and effectiveness of dofetilide in patients with paroxysmal atrial fibrillation and normal left ventricular function. | Dofetilide is currently recommended as second-tier therapy to maintain sinus rhythm in patients with paroxysmal atrial fibrillation (PAF) and normal left ventricular function, yet limited data support this recommendation. We examined the safety and efficacy of dofetilide in this setting through a retrospective chart review. We evaluated patients who had symptomatic PAF, normal left ventricular function, and no significant valvular disease. The end points were complete suppression of symptomatic PAF and subjective symptomatic improvement with dofetilide treatment. Over a 3-year period, 34 patients who had failed previous antiarrhythmic therapy were included. Of these, 3 discontinued dofetilide treatment before discharge. Of the remaining 31 who continued treatment after discharge, it was eventually discontinued in 13. At 12 months, symptomatic improvement was observed in 18 of 31 patients, 6 of whom remained asymptomatic. Treatment with dofetilide in this study was successful in less than 1 in 5 patients. Despite careful precautions, serious proarrhythmias, the major limiting side effect of dofetilide, still occurred during long-term follow-up. |
8,671 | Electrical cardioversion for persistent atrial fibrillation or atrial flutter in clinical practice: predictors of long-term outcome. | Despite the results of Atrial Fibrillation Follow-up Investigation of Rhythm Management and Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation trials, which favour a general shift in atrial fibrillation (AF) therapeutic approach towards control of ventricular rate, a strategy based on restoration of sinus rhythm could still play a role in selected patients at lower risk of AF recurrence. We explored possible predictors of relapses after external electrical cardioversion among patients with persistent AF or atrial flutter (AFL). We analysed the clinical characteristics and conventional echocardiographic parameters of patients with persistent AF/AFL enrolled in an institutional electrical cardioversion programme. Among 242 patients (AF/AFL, 195/47; mean age 62+/-13 years), sinus rhythm was restored in 215 (89%) and maintained in 73 (34%) at a follow-up of 930 days (median). No baseline clinical/echocardiographic variables predicted acute efficacy of cardioversion at logistic regression analysis. However, two variables predicted long-term AF/AFL recurrence among patients with successful cardioversion at multivariate Cox's proportional hazards analysis: (i) duration of arrhythmia>or=1 year (HR, 2.07; 95% CI, 1.29-3.33) and (ii) presence of previous cardioversion (HR, 1.67; 95% CI, 1.17-2.38). These variables also presented high-positive predictive values (72% and 80% respectively). Whereas the high acute efficacy of electrical cardioversion (approximately 90%) does not appear to be predictable, two simple clinical variables could help identify patients at higher risk of long-term AF/AFL recurrence after successful electrical cardioversion. We think there could be a case for initially attempting external electrical cardioversion to patients who have had AF/AFL for <1 year. In such patients, the chance of long-term success appears to be relatively high. |
8,672 | Catheter ablation of cardiac arrhythmias guided by electroanatomic imaging (CARTO): a single-center experience. | Catheter ablation is assuming a larger role in the management of patients with cardiac arrhythmias. Conventional fluoroscopic catheter mapping has limited spatial resolution and involves prolonged fluoroscopy. The non-fluoroscopic electroanatomic mapping technique (CARTO) has been developed to overcome these drawbacks.</AbstractText>To report the early and late outcome in patients with different arrhythmias treated with radiofrequency ablation combined with the CARTO mapping and navigation system.</AbstractText>The study cohort comprised 125 consecutive patients with different cardiac arrhythmias referred to our center from January 1999 to July 2005 for mapping and/or ablation procedures using the CARTO system. Forty patients (32%) had previous failed conventional ablation or mapping procedures and were referred by other centers. The arrhythmia included atrial fibrillation (n = 13), atrial flutter (n = 38), atrial tachycardia (n = 25), ventricular tachycardia (n = 24), arrhythmogenic right ventricular dysplasia (n = 9), and supraventricular tachycardia (n = 16).</AbstractText>During the study period, a total of 125 patients (mean age 49 +/- 19 years, 59% males) underwent electrophysiological study and electroanatomic mapping of the heart chambers. Supraventricular arrhythmias were identified in 92 patients (73%) and ventricular arrhythmias in 33 (27%). Acute and late success rates, defined as termination of the arrhythmia without anti-arrhythmic drugs, were 87% and 76% respectively. One patient (0.8%) developed a clinically significant complication.</AbstractText>The CARTO system advances our understanding of arrhythmias, and increases the safety, efficacy and efficiency of radiofrequency ablation.</AbstractText> |
8,673 | Therapeutic hypothermia for comatose survivors after cardiac arrest. | Unconscious adults with spontaneous circulation after out-of-hospital cardiac arrest should be cooled to 32-34 degrees C (ILCOR recommendations, 2003) when the initial rhythm is ventricular fibrillation.</AbstractText>To assess the technique, safety and efficacy of mild induced hypothermia in patients after OHCA due to VF.</AbstractText>Patients were cooled using the MTRE CritiCool external cooling system. Cold intravenous fluids were added to achieve faster cooling in 17 patients. Data were collected prospectively and patients were analyzed according to their neurological outcome on discharge, defined by their cerebral performance category.</AbstractText>From February 2002 to September 2006, 51 comatose VF patients with OHCA underwent MIH. Treatment was discontinued early in five because of hemodynamic instability; goal temperature was reached in 98% and maintained for an average of 19.5 hours; 61% had a favorable outcome (CPC 1-2) and 37% died. Improved outcome was observed with longer hypothermia time and possibly when time from collapse to return of spontaneous circulation was < 25 minutes.</AbstractText>MIH, using an external cooling system, is simple and feasible, reduces mortality and protects neurological function. Four major factors seem to influence outcome: age, co-morbidities, duration of hypothermia, and possibly the length of time from collapse to return of spontaneous circulation.</AbstractText> |
8,674 | Late mortality and determinants in patients with heart failure and preserved systolic left ventricular function: the Israel Nationwide Heart Failure Survey. | Heart failure with preserved systolic left ventricular function is a major cause of cardiac disability.</AbstractText>To examine the prevalence, characteristics and late clinical outcome of patients hospitalized with HF-PSF on a nationwide basis in Israel.</AbstractText>The Israel nationwide HF survey examined prospectively 4102 consecutive HF patients admitted to 93 internal medicine and 24 cardiology departments in all 25 public hospitals in the country. Echocardiographic LV function measurements were available in 2845 patients (69%). The present report relates to the 1364 patients who had HF-PSF (LV ejection fraction > or = 40%).</AbstractText>Mortality of HF-PSF patients was high (in-hospital 3.5%, 6 months 14.2%, 12 months 22.0%), but lower than in patients with reduced systolic function (all P < 0.01). Mortality was higher in patients with HF as the primary hospitalization diagnosis (16.0% vs. 12.5% at 6 months, P = 0.07 and 26.2% vs. 18.0% at 12 months, P = 0.0002). Patients with HF-PSF who died were older (78 +/- 10 vs. 71 +/- 12 years, P < 0.001), more often female (P = 0.05) and had atrial fibrillation more frequently (44% vs. 33%, P < 0.01). There was also a relationship between mortality and pharmacotherapy: after adjustment for age and co-morbid conditions, mortality was lower in patients treated with angiotensin-converting enzyme inhibitors (P = 0.0003) and angiotensin receptor blockers (P = 0.002) and higher in those receiving digoxin (P = 0.003) and diuretic therapy (P = 0.009).</AbstractText>This nationwide survey highlights the very high late mortality rates in patients hospitalized for HF without a decrease in systolic function. The findings mandate a focus on better evidence-based treatment strategies to improve outcome in HF-PSF patients.</AbstractText> |
8,675 | Left ventricular diastolic dysfunction in essential hypertension. | T Diastolic dysfunction is very frequent and is actually sign of manifest heart weakness. Over 40% of patients with heart weakness have isolated left ventricular diastolic dysfunction (LVDD). New diagnostics methods as Doppler Echocardiography with close monitoring enables precise and early LVDD diagnose. In all diastolic phases artery hypertension weakens relaxation and left ventricular hypertrophy (LVH) weakens compliance also. The purpose of this study is to demonstrate importance of all LVDD. Doppler echocardiography parameters usage and its important echocardiography characteristic in case of hypertensive patients. This study represents 64 patients with essential hypertension - random sample. Three patients had atrial fibrillation. Besides anamnestic data collection, echocardiography evaluation was undertaken on all patients. For LVDD diagnose following parameters were used: isovolumic relaxation time (IVRT), peak early filling velocity (E), peak atrial filling velocity (A), E/A ratio, DT (deceleration time), left ventricular (LV) mass. Left ventricular hypertrophy (LVH) was verified for 57 patients. Seven hypertensive patients didn't have verified LVH. Comparing patients with LVH with those without LVH differences were observed: patients with LVH had a longer IVRT, lower E/A ratio, A wave growth, IVRT directly correlates with LV mass increase and backward correlation LV mass with E/A was noticed. Among patients with LVH with E/A ratio =or> 1-1,5 and based on transmitral flow we used IVRT duration and pulse Doppler with volume sample over lateral mitral annulus measuring mitral annulus velocity. It appeared that it corresponds with IVRT duration in LVDD evaluation. Patients with atrial fibrillation had considerably extended IVRT that indicates LVDD existence. Patients with left ventricular hypertrophy were older and they have higher left ventricular mass comparing with patients without left ventricular hypertrophy. In case of patients with essential hypertension all above mentioned LVDD parameters have to be defined, specially IVRT duration for determination of LVDD existence in case of all patients with essential hypertension with and without LVH and in case of associated atrial fibrillation presence. It is necessary to tend to, as early as possible, detect LVDD and it's prevention with improved essential hypertension monitoring. |
8,676 | Complications of hypertension and the role of angiotensin receptor blockers in hypertension trials. | Hypertension is a high-prevalence disease that may affect several organs. In recent years, data have accumulated indicating that angiotensin II receptor blockers (ARBs) may have a supplementary effect beyond lowering blood pressure. The aim of this review is to evaluate the impact of ARBs on the most important complications of hypertension--heart, cerebrovascular and renal diseases, and metabolic complications--based on the findings from large clinical hypertension trials. The results may indicate that ARBs have a superior effect compared with placebo or other antihypertensive drugs in order to prevent left ventricular hypertrophy, atrial fibrillation, stroke, renal disease and diabetes mellitus, while there appears to be no blood pressure-independent superior effect of ARBs regarding prevention of myocardial infarction or heart failure. |
8,677 | The automated external defibrillator. | Sudden death claims 250,000 lives annually in the U.S. The vast majority of such events are due to ventricular fibrillation and ventricular tachycardia. Even though these arrhythmias can be converted if treated promptly, less than 5% of victims of out-of-hospital cardiac arrest survive to hospitalization. This poor survival is often due to delay in the initiation of quality CPR and defibrillation. Several clinical studies have evaluated the use of an AED by nontraditional emergency medical providers and by laypersons in Public Access Defibrillation programs. These studies have demonstrated a significant improvement in survival due to earlier access to defibrillation provided by the AED. The AED has proven to be safe, reliable, and efficacious in the diagnosis and treatment of ventricular arrhythmias when employed by lay providers/rescuers in a variety of outpatient settings. Society has embraced these data and legislation has been passed that supports the implementation of PAD programs into communities and protects lay rescuers and organizations implementing these programs from liability. Concerns about cost versus benefit still serve as barriers to widespread implementation of PAD programs, but with the declining cost of AEDs and increased public awareness, many communities have initiated PAD programs. We encourage widespread implementation of PAD programs and enhanced public awareness about basic life support, with the expectation that such efforts will enhance survival of out of hospital cardiac arrest. |
8,678 | NaviStar ThermoCool catheter for ventricular tachycardia. | Despite the relatively short history of catheter ablation, it has clearly demonstrated high efficacy and safety in treating a wide spectrum of cardiac arrhythmias. An important contributor to this success has been the rapid incorporation of evolving technologies that have changed the practice of electrophysiology remarkably. The introduction of irrigated radiofrequency ablation has allowed electrophysiologists to tackle complex arrhythmias, such as atrial fibrillation and ventricular tachycardia, with a higher success rate. Similarly, the introduction of 3D mapping systems has enhanced our understanding of arrhythmia mechanisms and allowed for integration of electrophysiologic and anatomically guided ablation. In 2006, the US FDA approved the Navistar ThermoCool ablation catheter, which incorporates an irrigated tip design with electroanatomical guidance, for ventricular tachycardia ablation. The design of this catheter, its clinical profile, its potential advantages and possible complications associated with its use in ventricular tachycardia ablation are discussed herein. |
8,679 | Acute heart failure syndromes: clinical scenarios and pathophysiologic targets for therapy. | Acute heart failure syndromes (AHFS) represent the most common discharge diagnosis in patients over age 65 years, with an exceptionally high mortality and readmission rates at 60-90 days. Recent surveys and registries have generated important information concerning the clinical characteristics of patients with AHFS and their prognosis. Most patients with AHFS present either with normal systolic blood pressure or elevated blood pressure. Patients who present with elevated systolic blood pressure usually have pulmonary congestion, a relatively preserved left ventricular ejection fraction (LVEF), are often elderly women, and their symptoms develop typically and abruptly. Patients with normal systolic blood pressure present with systemic congestion, reduced LVEF, are usually younger with a history of chronic HF, and have symptoms that develop gradually over days or weeks. In addition to the abnormal hemodynamics (increase in pulmonary capillary wedge pressure and/or decrease in cardiac output) that characterize patients with AHFS, myocardial injury, which may be related to a decrease in coronary perfusion and/or further activation of neurohormones and renal dysfunction, probably contributes to short-term and post-discharge cardiac events. Patients with AHFS also have significant cardiac and noncardiac underlying conditions that contribute to the pathogenesis of AHFS, including coronary artery disease (ischemia, hibernating myocardium, and endothelial dysfunction), hypertension, atrial fibrillation, and type 2 diabetes mellitus. Therefore, the targets of therapy for AHFS should be not only to improve symptoms and hemodynamics but also to preserve or improve renal function, prevent myocardial damage, modulate neurohumoral and inflammatory activation, and to manage other comorbidities that may cause and/or contribute to the progression of this syndrome. |
8,680 | [QTc-prolonging drugs and the risk of sudden death]. | Various drugs can be associated with QT prolongation. A prolonged QT interval leads to an increased risk for the development of ventricular tachyarrhythmias, particularly polymorphic ventricular tachycardia (torsades de pointes). Polymorphic arrhythmia may rapidly develop into ventricular fibrillation and cause sudden death. Torsades de pointes is classically associated with early depolarization. This review article discusses the mechanisms of QTc prolongation and triggering factors for proarrhythmia, drugs that prolong QT interval (class III antiarrhythmic agents, antimicrobial agents - fluoroquinolone and macrolide antibiotics, antipsychotic and antidepressant drugs, agents used in general anesthesia, antimycotics, and several other drugs), nonpharmacological and pharmacological risk factors for arrhythmias (due to pharmacokinetic-pharmacodynamic interactions), the treatment and recommendations to prevent arrhythmia related to QT prolongation. |
8,681 | Risk of thromboembolism in heart failure: an analysis from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). | In patients with heart failure, rates of clinically apparent stroke range from 1.3% to 3.5% per year. Little is known about the incidence and risk factors in the absence of atrial fibrillation. In the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), 2521 patients with moderate heart failure were randomized to receive amiodarone, implanted cardioverter-defibrillators (ICDs), or placebo.</AbstractText>We determined the incidence of stroke or peripheral or pulmonary embolism in patients with no history of atrial fibrillation (n=2114), predictors of thromboembolism and the relationship to left ventricular ejection fraction. Median follow-up was 45.5 months. Kaplan-Meier estimates (95% CIs) for the incidence of thromboembolism by 4 years were 4.0% (3.0% to 4.9%), with 2.6% (1.1% to 4.1%) in patients randomized to amiodarone, 3.2% (1.8% to 4.7%) in patients randomized to ICD, and 6.0% (4.0% to 8.0%) in patients randomized to placebo (approximate rates of 0.7%, 0.8%, and 1.5% per year, respectively). By multivariable analysis, hypertension (P=0.021) and decreasing left ventricular ejection fraction (P=0.023) were significant predictors of thromboembolism; treatment with amiodarone or ICD treatment was a significant predictor of thromboembolism-free survival (P=0.014 for treatment effect; hazard ratio [95% CI] versus placebo, 0.57 [0.33 to 0.99] for ICD; 0.44 [0.24 to 0.80] for amiodarone). Inclusion of atrial fibrillation during follow-up in the multivariable model did not affect the significance of treatment assignment as a predictor of thromboembolism.</AbstractText>In the SCD-HeFT patient cohort, which reflects contemporary treatment of patients with moderately symptomatic systolic heart failure, patients experienced thromboembolism events at a rate of 1.7% per year without antiarrhythmic therapy. Those treated with amiodarone or ICDs had lower risk of thromboembolism than those given placebo. Hypertension at baseline and lower ejection fraction were independent predictors of risk.</AbstractText> |
8,682 | Role of programmed ventricular stimulation in patients with Brugada syndrome: a meta-analysis of worldwide published data. | Brugada syndrome (BS) is an ion channelopathy with the risk of sudden cardiac death. The role of programmed ventricular stimulation (PVS) in risk stratification has been controversially discussed. Therefore, we performed a meta-analysis on the prognostic role of PVS in BS.</AbstractText>A Medline search until July 2006 documented 822 entries for BS. Only English publications with > 10 patients and a follow-up period were considered (n = 15). Patients [n = 1217; 974 males (80%)] were divided into three groups: survived sudden cardiac arrest (SCA) [n = 222 (18%)], syncope (Syncope) [n = 275 (23%)], and asymptomatic patients (Asympt) [n = 720 (59%)]. PVS was conducted in 1036 patients (85%). In 548 patients (53%), sustained ventricular tachyarrhythmias (VT) or ventricular fibrillation (VF) was inducible. During follow-up (34 +/- 40 months), VT/VF occurred in 141 patients. SCA bore the highest chance for a VT/VF occurrence during follow-up [odds ratio (OR) 14.4 compared with asymptomatic patients; P < 0.0005]. However, except for one study, the OR for VT/VF during follow-up in relation to VT/VF inducibility was non-significant (OR 1.5; P = ns).</AbstractText>The main finding is that we were unable to identify a significant role of PVS with regard to arrhythmic events during follow-up in BS, thus questioning the role of PVS for risk stratification in patients with BS. Patients with BS and survived SCA show the highest chance for VT/VF occurrence during follow-up.</AbstractText> |
8,683 | Cardiology at Westmead Hospital from 1990 to 2007. | Professor John Uther was the Director of Cardiology at Westmead Hospital from 1979 to 1990. Professor David Ross and Dr Pramesh Kovoor followed in this capacity subsequently. Networking between Westmead and metropolitan hospitals was established by conjoint appointment of cardiologists across the facilities. Westmead has maintained its excellence in electrophysiology with leadership in operative/catheter ablation of atrial fibrillation, development of catheter for mapping tricuspid annulus, multi-electrode mapping and intramural ablation of ventricular tachycardia and paediatric electrophysiology. Dr. Hugh Paterson became the Director of Cardiothoracic Surgery in 2006. The previous Directors were Dr. David Johnson, Dr. Graham Nunn and Associate Professor Richard Chard. Westmead established an area-wide acute infarct angioplasty service for all patients presenting to any facility in Western Sydney along with triage of chest pain in the ambulance in 2004. Collaborative sessions with vascular surgeons for non-coronary interventions commenced in 2005. In the future, Westmead will continue its excellence in vascular and electrophysiological interventions. Imaging (echocardiography, computerised tomography and magnetic resonance imaging) will be a major part of the service. Innovation in basic science is likely. Overall, it will be an exciting time to be a cardiologist, vascular surgeon or cardiothoracic surgeon at Westmead. |
8,684 | Demographic, clinical and echocardiographic determinants of B-type natriuretic peptide plasma concentration. A population-based study. | The aim of this study was to identify determinants of plasma B-type natriuretic peptide (BNP) levels at the population level.</AbstractText>In a cross-sectional study, the authors evaluated 559 community subjects aged > or = 45 years. The association between plasma BNP concentration and the hypothesized determinants was assessed by linear regression using the natural logarithm of BNP plasma concentration as the dependent variable and separate models for each gender.</AbstractText>Plasma BNP was significantly higher in women. BNP increased with age, more steeply in men than women (p < 0.05 for the interaction). In univariate analysis, BNP was associated with left ventricular systolic dysfunction (LVSD), moderate to severe valvular abnormalities, left atrial diameter/body surface area, left ventricular mass index, systolic blood pressure, lower creatinine clearance and jugular venous distension. In women it was also associated with left ventricular end-diastolic diameter/body surface area and atrial fibrillation, and in men with changes in the segmental wall motion index. The final multivariate models included age, LVSD and left atrial size as significant independent determinants of BNP level, explaining 16.8% and 32.3% of BNP variability in women and men respectively.</AbstractText>The association between BNP and left atrial size independently of systolic dysfunction suggests that BNP might reflect subclinical diastolic abnormaltes. False positive BNP levels for the diagnosis of left ventricular systolic dysfunction and heart failure are probably due to high BNP levels in people with cardiac abnormalities not detected by echocardiography.</AbstractText> |
8,685 | Conduction abnormalities and anaesthesia. | Accurate identification of patients at risk for ventricular arrhythmias is critical to prevent sudden cardiac death. The perioperative period is usually regarded as one of risk for potential triggering conditions. This review focuses on the anaesthesiologic risk of inherited arrhythmias whose aetiology is a mutation in genes encoding cardiac ion channels in the absence of structural heart abnormalities.</AbstractText>Genetic analysis identifies the genes whose expressions generate ion channel and regulating or anchoring subunits; electrophysiology can study the role of each ion current during cardiac fibrillation and develop many tests for risk. There is, however, a great heterogeneity of clinical phenotype and many histological studies detecting structural heart alterations despite negative noninvasive evaluations.</AbstractText>For some ion channel diseases, a therapy has been established; for others, the therapy and risk stratification are still matters of concern, and it is necessary to evaluate the new tools and tests available. For the highly lethal complication of these 'channellopathies', anaesthesia should proceed with caution in the light of the characteristics of each arrhythmia to prevent complications.</AbstractText> |
8,686 | Comparison of cardiac structural and functional changes in obese otherwise healthy adults with versus without obstructive sleep apnea. | Obstructive sleep apnea (OSA) and obesity have been linked to systolic and diastolic dysfunction of the left ventricle. Right ventricular function is poorly understood in the 2 clinical conditions. Data from this study show that otherwise healthy obese patients with OSA had increased an left atrial volume index compared with similarly obese patients without OSA (16.3 +/- 1.2 ml/m in obese patients without OSA vs 20.2 +/- 1.0 ml/m in those with OSA, p = 0.02) and altered diastolic function reflected by changes in mitral annular late diastolic velocity (-5.7 +/- 0.7 cm/s in obese patients without OSA vs -7.3 +/- 0.7 cm/s in those with OSA, p = 0.007), mitral annular early diastolic velocity (-7.9 +/- 0.6 cm/s in obese patients without OSA vs -6.4 +/- 0.3 cm/s in those with OSA, p = 0.05), and early to late diastolic annular ratio >1 (82% of obese patients without OSA vs 26% of those with OSA, p = 0.001), which may be signs of early subclinical impairment of cardiac function. Importantly, healthy obese subjects had similarly increased left ventricular mass compared with obese patients with OSA but normal diastolic function and left atrial size. There was a trend toward abnormal right ventricular filling in patients with OSA, measured by altered superior vena cava diastolic velocity during expiration (-15 +/- 2 cm/s in obese patients without OSA vs -10 +/- 3 cm/s in those with OSA, p = 0.2) and a tendency toward diastolic dysfunction reflected by decreased lateral tricuspid annular early diastolic velocity (-7.2 +/- 0.5 cm/s in obese patients without OSA vs -6.1 +/- 0.5 cm/s in those with OSA, p = 0.1) beyond that seen in obesity alone. In conclusion, OSA independent of obesity may induce cardiac changes that could predispose to atrial fibrillation and heart failure. |
8,687 | Comparison of usefulness of cardiac resynchronization therapy in patients with atrial fibrillation and heart failure versus patients with sinus rhythm and heart failure. | The prevalence of atrial fibrillation (AF) in patients with heart failure is high, but data about the effects of cardiac resynchronization therapy (CRT) in patients with chronic AF are scarce. In this prospective observational study of 263 consecutive patients, CRT was performed in 96 patients (37%) with chronic AF and 167 patients (63%) with sinus rhythm (SR). Echocardiographic and clinical parameters were evaluated at baseline and 3 and 12 months. Reverse left ventricular (LV) remodeling is defined as LV end-systolic volume decrease > or =10%. Hospitalization rates for heart failure in the year before and after implantation were compared. Baseline characteristics between patients with and without AF were similar, but the AF group had smaller LV end-systolic and end-diastolic volumes and larger left atrial dimensions. New York Heart Association class, 6-minute walking distance, quality-of-life score, LV ejection fraction, and mitral regurgitation improved significantly at 3 and 12 months in both groups, and the changes were similar. Reverse LV remodeling after 3 and 12 months was 74% and 82% (AF group) versus 77% and 83%, respectively (SR group, p = 0.79). After 1 year, cardioversion had occurred in 25% of patients with AF. In the year after implantation, significant decreases in hospitalizations for heart failure in both groups (84% and 90%) were documented. Long-term mortality was almost equal in both groups. In conclusion, this large-scale study shows that the benefit of CRT in patients with chronic AF and heart failure is similar to that in patients with SR. Patients with chronic AF and heart failure should be considered candidates for CRT. |
8,688 | The role of pacing in rhythm control and management of atrial fibrillation. | Atrial fibrillation is the most common sustained cardiac arrhythmia and is increasing in prevalence with an ageing population. As the arrhythmia is often asymptomatic the true prevalence is likely even higher. Largely because of stroke this arrhythmia places a huge financial burden on the health economy. Despite this, large studies assessing rate versus rhythm control have been equivocal. Because of the ineffectiveness of pharmacological therapy much research effort has been undertaken in device and ablative approaches to rhythm management. Although catheter ablation has gained favour because of the high success rates the technique requires considerable expertise and still has a significant complication profile maintaining interest in pacing therapies for atrial fibrillation. Dual chamber versus single-chamber ventricular pacing has been shown to significantly reduce the incidence of atrial fibrillation. Research is currently underway to see if minimising the deleterious effects of right ventricular apical pacing could further increase the benefits of atrioventricular synchronous pacing. Several studies show some (albeit variable) reduction in AF burden with anti-AF algorithms in the setting of bradycardia. Antitachycardia pacing, on the other hand, has not been shown to treat AF in a randomised trial despite the successful termination of co-existent atrial tachycardias. There is increasing evidence that alternative atrial pacing sites may treat AF by improving atrial function. Furthermore, these strategies coupled with other therapies in a 'hybrid approach' have also showed promising results. |
8,689 | Bepridil reverses atrial electrical remodeling and L-type calcium channel downregulation in a canine model of persistent atrial tachycardia. | This study tested whether bepridil, a multichannel blocker, would reverse electrical remodeling induced by persistent atrial tachycardia.</AbstractText>Fourteen dogs were subjected to rapid atrial pacing at 400 bpm for 6 weeks after atrioventricular block was created to control the ventricular rate. During the study period, seven dogs were given placebo for 6 weeks (Control group), and seven were given placebo for 3 weeks, followed by 3 weeks of bepridil (10 mg/kg/day, Bepridil group). The atrial effective refractory period (ERP) and the inducibility and duration of atrial fibrillation (AF) were determined on a weekly basis. After 6 weeks, expression of L-type calcium channel alpha1C messenger ribonucleic acid (mRNA) was quantified by real-time reverse transcription-polymerase chain reaction. In the Control group, ERP was shortened and the inducibility and duration of AF increased through the 6-week period. In the Bepridil group, the same changes occurred during the first 3 weeks, but were gradually reversed with bepridil. After 6 weeks, ERP was longer, AF inducibility was lower, and AF duration was shorter in Bepridil group than in the Control group. Expression of alpha1C mRNA was decreased by 64% in the Control group (P < 0.05 vs sham), but in the Bepridil group, it was not different compared with the sham dogs. As a whole group of dogs, ERP was positively correlated with alpha1C mRNA expression.</AbstractText>Bepridil reverses the electrophysiological consequences of atrial remodeling to some extent and L-type calcium channel downregulation in a canine model of atrial tachycardia.</AbstractText> |
8,690 | Dronedarone: drondarone, SR 33589, SR 33589B. | Dronedarone, a potassium channel antagonist, is chemically related to amio-darone. It is being developed by sanofi-aventis as a class III antiarrhythmic agent for the treatment of atrial fibrillation and atrial flutter in the US and Europe. Dronedarone has a favourable benefit/risk ratio, with the absence of any proarrhythmic effects. Sanofi merged with Synthélabo to form Sanofi-Synthélabo in 1999. In August 2004, Sanofi-Synthelabo merged with Aventis to form sanofi-aventis. The ATHENA trial is a multinational, randomised, double-blind trial evaluating the effects of dronedarone (400mg bid) compared with placebo, over a minimum 12-month follow-up period, in patients with atrial fibrillation or flutter. The trial is investigating the efficacy of dronedarone in preventing cardiovascular hospitalisations or death from any cause. Enrolment was extended to 4300 patients in order to attain the planned rate of adverse events; patient recruitment is ongoing.Previously, sanofi-aventis completed two pivotal phase III trials in atrial fibrillation. The trials, EURIDIS (EURopean trial In atrial fibrillation or flutter patients for the maintenance of Sinus rhythm) and ADONIS (American-Australasian trial with DronedarONe In atrial fibrillation or flutter patients for the maintenance of Sinus rhythm), involved 1237 patients who were in sinus rhythm at the time of randomisation. Results showed dronedarone to have anti-arrhythmic effects and a favourable benefit/risk ratio, with the absence of any proarrhythmic effect.Another trial, ERATO (Efficacy and safety of dronedARone for The cOntrol of ventricular rate), took place in 35 centres across nine European countries assessing dronedarone in 174 patients with permanent atrial fibrillation. Dronedarone was in phase II trials in Japan for the treatment of atrial fibrillation; however, no recent developments have been reported. |
8,691 | Study for relevance of the acute myocardial ischemia to arrhythmia by the optical mapping method. | Ventricular arrhythmias are commonly observed in patients with acute coronary occlusion and ischemia. The purpose of the present study is to determine ischemic electrophysiological effects and their role in ischemia-induced arrhythmia. Optical mapping of the membrane potential with voltage-sensitive dyes was used in the study. The mapping was performed with di-4-ANEPPS in Langendorff-perfused rabbit hearts. The excitation-contraction decoupler 2,3-butanedione monoxime was used to suppress motion artifacts caused by contraction of the heart. The acute global ischemia was developed by a rapid reduction of the flow rate. The experiments revealed that ischemic tissues were characterized by an obvious reduction in action potential duration and action potential upstroke, slower conduction velocity (CV) and the property of post-repolarization refractoriness. Moreover, the magnitude of CV reduced both in control and ischemia when the pacing cycle length was short. CV reduction was even early in ischemia, resulting in a broader curve during ischemia. Moreover, the dominant frequency of ventricular tachycardia/ventricular fibrillation (VT/VF) in ischemia was less than that in control, implying a decreasing tendency of VT/VF frequency for low excitability. Therefore, combined with our previous simulation study, the dynamic changes of CV and longer refractory period were suggested to play an important role in the ischemia-related arrhythmia. Low excitability in ischemic tissue was the fundamental mechanism in it. |
8,692 | Inductionless or limited shock testing is possible in most patients with implantable cardioverter- defibrillators/cardiac resynchronization therapy defibrillators: results of the multicenter ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations). | Implantable cardioverter-defibrillators and cardiac resynchronization therapy defibrillators have relied on multiple ventricular fibrillation (VF) induction/defibrillation tests at implantation to ensure that the device can reliably sense, detect, and convert VF. The ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations) is the first large, multicenter, prospective trial comparing vulnerability safety margin testing versus defibrillation safety margin testing with a single VF induction/defibrillation.</AbstractText>A total of 426 patients receiving an implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator underwent vulnerability safety margin or defibrillation safety margin screening at 14 J in a randomized order. After this, patients underwent confirmatory testing, which required 2 VF conversions without failure at < or = 21 J. Patients who passed their first 14-J and confirmatory tests, irrespective of the results of their second 14-J test, had their devices programmed to a 21-J shock for ventricular tachycardia (VT) or VF > or = 200 bpm and were followed up for 1 year. Of 420 patients who underwent 14-J vulnerability safety margin screening, 322 (76.7%) passed. Of these, 317 (98.4%) also passed 21-J confirmatory tests. Of 416 patients who underwent 14-J defibrillation safety margin screening, 343 (82.5%) passed, and 338 (98.5%) also passed 21-J confirmatory tests. Most clinical VT/VF episodes (32 of 37, or 86%) were terminated by the first shock, with no difference in first shock success. In all observed cases in which the first shock was unsuccessful, subsequent shocks terminated VT/VF without complication.</AbstractText>Although spontaneous episodes of fast VT/VF were limited, there was no difference in the odds of first shock efficacy between groups. Screening with vulnerability safety margin or defibrillation safety margin may allow for inductionless or limited shock testing in most patients.</AbstractText> |
8,693 | Annual rate of transvenous defibrillation lead defects in implantable cardioverter-defibrillators over a period of >10 years. | The number of patients with longer follow-up after implantation of an implantable cardioverter-defibrillator is increasing continuously. Defibrillation lead failure is a typical long-term complication. Therefore, the long-term reliability of implantable cardioverter-defibrillator leads has become an increasing concern. The aim of the present study was to assess the annual rate of transvenous defibrillation lead defects related to follow-up time after lead implantation.</AbstractText>A total of 990 consecutive patients who underwent first implantation of an implantable cardioverter-defibrillator between 1992 and May 2005 were analyzed. Median follow-up time was 934 days (interquartile range, 368 to 1870). Overall, 148 defibrillation leads (15%) failed during the follow-up. The estimated lead survival rates at 5 and 8 years after implantation were 85% and 60%, respectively. The annual failure rate increased progressively with time after implantation and reached 20% in 10-year-old leads (P<0.001). Lead defects affected newer as well as older models. Patients with lead defects were 3 years younger at implantation and more often female. Multiple lead implantation was associated with a trend to a higher rate of defibrillation lead defects (P=0.06). The major lead complications were insulation defects (56%), lead fractures (12%), loss of ventricular capture (11%), abnormal lead impedance (10%), and sensing failure (10%).</AbstractText>An increasing annual lead failure rate is noted primarily during long-term follow-up and reached 20% in 10-year-old leads. Patients with lead defects are younger and more often female.</AbstractText> |
8,694 | The impedance threshold valve for adult cardiopulmonary resuscitation: a review of the literature. | Heart-lung interaction is an important parameter in the understanding of blood-flow induction during cardiopulmonary resuscitation. The impedance threshold valve is a device which has been created to increase venous return by occluding the airway during the decompression phase of cardiopulmonary resuscitation. This review analyzes the available literature focusing on the rationale of this device.</AbstractText>Animal and human studies suggest that the impedance threshold valve increases cardiopulmonary circulation by taking advantage of the kinetic energy of the movement of the chest wall during standard cardiopulmonary resuscitation or active chest-wall decompression. When used in conjunction with active compression/decompression cardiopulmonary resuscitation during clinical evaluation, addition of the impedance valve resulted in sustained systolic and diastolic pressures as well as improvement of vital-organ blood flow. Recent studies have also found an increase in short-term survival rates.</AbstractText>It seems clear, from both animal and human data, that enhancement of preload by a decrease in the intrathoracic pressures in the decompression phase improves overall cardiopulmonary resuscitation efficacy. By this means, the impedance threshold valve may be beneficial in patients in asystole or shock-refractory ventricular fibrillation. The potential long-term benefits of this new valve remain under investigation.</AbstractText> |
8,695 | Monitoring the quality of cardiopulmonary resuscitation. | Numerous recent reports have described limitations in the quality of cardiopulmonary resuscitation. Thus, there has been increasing interest in the techniques available to monitor quality. This review focuses on the major publications since the review published by the International Liaison Committee on Resuscitation in 2005. Some key articles published prior to this time period have also been included.</AbstractText>A number of devices can monitor various components of the quality of cardiopulmonary resuscitation. End-tidal CO2 measurement assists in confirming placement of endotracheal tubes, correlates with cardiac output and detects the return of spontaneous circulation. Turbine flow-meters monitor respiratory rate and tidal volume. Transthoracic impedance monitoring measures respiratory rate, and may assist in confirmation of endotracheal tube placement. A new mechanical device (CPREzy) and a new defibrillator/monitor allow estimation of depth (and rate) of compressions. Ventricular-fibrillation waveform analysis may facilitate better timing of defibrillation. Echocardiography detects conditions that may impair the quality of cardiopulmonary resuscitation.</AbstractText>Many options are available to monitor the quality of cardiopulmonary resuscitation. Some have significant limitations, and others are only readily available in hospital. The use of the information from this more intensive monitoring promises to improve outcomes of cardiopulmonary resuscitation.</AbstractText> |
8,696 | Attitudes of Ohio dentists and dental hygienists on the use of automated external defibrillators. | The American Heart Association reports that approximately 220,000 people die each year of sudden cardiac arrest. In ventricular fibrillation (VF), the most common abnormal heart rhythm that causes cardiac arrest, the heart's electrical impulses suddenly become chaotic, often without warning. Death will follow within minutes if the victim is not treated appropriately, and the only known treatment is defibrillation. An automated external defibrillator (AED) can restore a victim's normal heart rhythm by providing defibrillation. The purpose of this study was to gather data from dentists and dental hygienists in Ohio on their use of and attitudes toward using AEDs in dental offices. Six percent of Ohio dentists and dental hygienists were randomly selected to receive a twenty-three question survey related to their use of and attitudes toward their use of AEDs in dental offices. Thirty-three percent (244) of the surveys were returned; 41 percent of the respondents were dentists, and 59 percent were dental hygienists. Six percent said they have had to administer nitroglycerin to a patient during a dental visit; 5 percent have performed CPR on a patient in the dental office; and 78 percent said their last CPR training course included training on an AED. Eleven percent said there was an AED at their dental office. With the increased likelihood of dealing with a cardiac emergency in the dental office setting and the willingness of dental professionals to use an AED, all dental offices should consider obtaining an AED. Dental educators should become familiar with current protocols for handling cardiac medical emergencies in the dental office and prepare dental and dental hygiene students with the skills necessary to manage patients with cardiac emergencies. Graduating dental students entering private practice may want to consider the AED as part of their medical emergency office protocol. |
8,697 | Rhythm discrimination during uninterrupted CPR using motion artifact reduction system. | Due to motion artifact in the ECG caused by chest compressions automatic external defibrillators (AEDs) have difficulty recognizing ventricular fibrillation (VF) during cardiopulmonary resuscitation (CPR). Frequent interruption of CPR is required for artifact-free ECG interpretation, but these interruptions reduce the efficacy of CPR. We developed a motion artifact reduction system (MARS), based on adaptive noise cancellation techniques, for use during CPR. We hypothesized that this system would allow for automated rhythm discrimination during uninterrupted CPR.</AbstractText>Thirteen swine underwent CPR during normal sinus rhythm (NSR) and repeated inductions of VF and asystole, using an automated device that uses a load-distributing band to compress the anterior chest. A single ECG lead and the instantaneous compression force signal were sampled during continuous CPR and fed to MARS, which in turn provided a filtered ECG signal in which artifacts that correlated with compression force were suppressed. The filtered and unfiltered ECGs were then fed simultaneously, and in real time, to three pairs of defibrillators with rhythm discrimination functions. During CPR, non-shockable rhythms were correctly classified by the defibrillators in 59 of 63 instances using the raw ECG, and 60 of 63 instances using the MARS-filtered ECG (p=N.S.). During CPR, VF was correctly classified in 35 of 222 attempts using the raw ECG, and in 310 of 318 cases using the MARS-filtered ECG (p<0.001). As control, when CPR was not applied, all rhythms were correctly identified by each defibrillator using either the raw ECG or the filtered ECG.</AbstractText>Motion artifact reduction by adaptive noise cancellation allows for recognition of VF during uninterrupted automated CPR, while this is rarely possible based on the raw ECG. Incorporation of this signal processing strategy may obviate the need for interruptions in chest compression and thus enhance CPR efficacy.</AbstractText> |
8,698 | Supraventricular arrhythmias in noncompaction of left ventricle: is this a frequent complication? | Isolated left ventricular noncompaction is the result of incomplete myocardial morphogenesis, leading to persistence of the embryonic myocardium. The condition is recognised by an excessively prominent trabecular meshwork and deep intertrabecular recesses of the left ventricle. Whether these intertrabecular recesses are a favorable substrate for supraventricular arrhythmias is unclear, even if the incidence of chronic heart failure seems to be high.</AbstractText>We evaluated a continuous series of 238 patients affected by noncompaction. In 4 cases the patients reported palpitations and in 4 an episode of syncope. Periodic holter monitoring was performed every 6 months for 4 years. Only 9 patients had documented atrial fibrillation. In no cases we observed supraventricular tachycardia.</AbstractText>Noncompaction alone does not seem to be a risk factor for supraventricular arrhythmias.</AbstractText> |
8,699 | Ventricular fibrillation: how do we put the genie back in the bottle? | I am deeply grateful and honored to receive the 2006 Distinguished Scientist Award from the Heart Rhythm Society. Many outstanding individuals have received this award since it was established in 1982, and it is humbling to realize that my small feet are walking in the footsteps of these giants. I would be remiss if I did not thank the numerous colleagues, fellows, and students who performed most of the work leading to the papers of which I am a coauthor. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.