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14,500 | Effects of a novel amiodarone-like compound SAR114646A on the pig atrium and susceptibility to ventricular fibrillation in dogs and pigs. | Amiodarone is one of the most effective antiarrhythmic drugs. However, poor solubility of this compound has limited its intravenous application. SAR11464A is a water-soluble amiodarone-like drug that lacks iodine and inhibits multiple cardiac ion channels in vitro. This study evaluated the antiarrhythmic efficacy of this drug in vivo. In porcine studies, atrial effective refractory period (AERP) was measured in pentobarbital-anesthetized thoracotomized pigs and atrial fibrillation (AF) was induced by a premature beat. Ventricular fibrillation (VF) was induced via either burst pacing or programmed electrical stimulation (a series of progressively shorter beats, S1-S5). In canine studies, VF was induced by a 2-min occlusion of the left circumflex coronary artery during the last minute of exercise in dogs with healed myocardial infarctions (n = 8). One week later, this test was repeated after pretreatment with SAR114646A (3.0 mg/kg, i.v., slow bolus). SAR114646A produced a significant dose-dependent prolongation of AERP, inhibited AF induced by a premature stimulus, and electrically induced VF in anesthetized pigs. At 1.0 and 3.0 mg/kg, i.v., it was superior to amiodarone, dofetilide, and flecainide. In dogs, SAR114646A did not alter any ECG parameter including QTc (control, 236.9 ± 8.5 ms vs. SAR, 237.2 ± 3.5 ms) but significantly reduced the incidence of VF, protecting six of eight animals (Fisher's exact test, P = 0.01). SAR114646A was effective against both atrial and ventricular arrhythmias without altering ventricular repolarization. These data suggest that the amiodarone-like drug SAR114646A may be an effective antiarrhythmic intervention that does not adversely prolong ventricular repolarization. |
14,501 | Cardiac aging: from molecular mechanisms to significance in human health and disease. | Cardiovascular diseases (CVDs) are the major causes of death in the western world. The incidence of cardiovascular disease as well as the rate of cardiovascular mortality and morbidity increase exponentially in the elderly population, suggesting that age per se is a major risk factor of CVDs. The physiologic changes of human cardiac aging mainly include left ventricular hypertrophy, diastolic dysfunction, valvular degeneration, increased cardiac fibrosis, increased prevalence of atrial fibrillation, and decreased maximal exercise capacity. Many of these changes are closely recapitulated in animal models commonly used in an aging study, including rodents, flies, and monkeys. The application of genetically modified aged mice has provided direct evidence of several critical molecular mechanisms involved in cardiac aging, such as mitochondrial oxidative stress, insulin/insulin-like growth factor/PI3K pathway, adrenergic and renin angiotensin II signaling, and nutrient signaling pathways. This article also reviews the central role of mitochondrial oxidative stress in CVDs and the plausible mechanisms underlying the progression toward heart failure in the susceptible aging hearts. Finally, the understanding of the molecular mechanisms of cardiac aging may support the potential clinical application of several "anti-aging" strategies that treat CVDs and improve healthy cardiac aging. |
14,502 | Effect of amiodarone on dispersion of ventricular repolarization in a canine congestive heart failure model. | The effects of amiodarone on ventricular electrophysiological parameters, especially the dispersion of ventricular repolarization, were investigated in a canine model of congestive heart failure (CHF). Dogs were randomized to either a control, amiodarone, CHF, or CHF+amiodarone group. Dogs in the CHF and CHF+amiodarone groups underwent 4-5 weeks of rapid ventricular pacing; dogs in the control and amiodarone groups underwent sham operation only. Amiodarone (20 mg/kg per day) was administered orally, beginning on postoperative Day 1, in the treatment groups; ventricular electrophysiological variables were evaluated 4-5 weeks after rapid pacing or sham operation. In CHF dogs, the transmural dispersion ventricular repolarization time (TDVRT) increased significantly. Amiodarone significantly decreased the TDVRT in CHF dogs. The ventricular fibrillation threshold (VFT) decreased in the CHF group. Amiodarone increased the VFT in CHF dogs. The TDVRT increased in CHF dogs, but amiodarone decreased TDVRT and increased VFT in these dogs. These results suggest a beneficial effect of amiodarone on malignant arrhythmias and may provide the basis for its use in CHF patients. |
14,503 | Outcomes of mild therapeutic hypothermia after in-hospital cardiac arrest. | Although the benefits of mild therapeutic hypothermia (MTH) in selected patients after out-of-hospital cardiac arrest have been consistently demonstrated, no controlled trial of MTH in selected patients after in-hospital cardiac arrest (IHCA) has been published. We sought to assess the benefit of MTH after IHCA in patients meeting our institutions IHCA MTH inclusion criteria.</AbstractText>A retrospective, historical control study was performed. During the 3-year period before and after the 2006 MTH protocol implementation at our institution, we identified a total of 118 patients admitted to our Medical Intensive Care Unit after resuscitation from an IHCA. Two blinded investigators identified all patients meeting our institutions MTH protocol inclusion criteria and the patients in each time period were compared. The primary outcome was discharge with good neurological function.</AbstractText>33 IHCA patients met MTH protocol inclusion criteria; 16 patients were admitted prior to MTH protocol implementation and thus were not treated with MTH post arrest while 17 patients were admitted after implementation and were all treated with MTH post arrest. 91% of patients had an arrest rhythm of asystole or pulseless electrical activity. Good neurological function at discharge was found in 24% of MTH patients and 31% of controls (P = .62).</AbstractText>No difference in neurological outcome at discharge was detected in predominantly non-shockable IHCA patients treated with MTH. This finding, if confirmed with further study, may define a population of patients for whom this costly and resource intensive therapy should be withheld.</AbstractText> |
14,504 | Left atrial expansion index for predicting atrial fibrillation and in-hospital mortality after coronary artery bypass graft surgery. | Atrial fibrillation (AF), a common complication after coronary artery bypass graft surgery (CABG), is associated with prolonged hospital stay. This prospective study assessed the accuracy of left atrial parameters and additional preoperative characteristics for predicting post-CABG AF and in-hospital mortality.</AbstractText>A total of 197 patients without hemodynamic-significant valvular problems, who received isolated CABG, were enrolled. Echocardiography was performed before CABG.</AbstractText>Compared with patients without post-CABG AF, those with post-CABG AF were older (71 vs 64 years, p<0.0001), had a higher incidence of CABG during index hospitalization of acute myocardial infarction and preoperative respiratory failure requiring ventilator support, lower left ventricular ejection fraction (0.41 vs 0.48, p<0.0001), lower left atrial expansion index (52.2% vs 93.3%, p<0.0001), and higher left ventricular filling pressure (24.2 vs 19.1 mm Hg, p<0.0001). Multivariate analysis of preoperative variables showed that independent predictors of AF included age (odds ratio [OR], 1.064; 95% confidence interval [CI], 1.022 to 1.107 per 1-year increase; p 0.002), maximal indexed left atrial volume (OR, 1.026; 95% CI, 1.002 to 1.051 per 1 mL/m2 increase; p 0.037) and left atrial expansion index (OR, 0.981; 95% CI, 0.962 to 0.998 per 1% increase; p 0.029). The left atrial expansion index was also significantly associated with in-hospital mortality (OR, 0.982; 95% CI, 0.951 to 0.996 per 1% increase; p 0.042). Incidence of post-CABG AF in patients with left atrial expansion index less than 120% progressively increased as left atrial expansion index decreased.</AbstractText>Left atrial expansion index independently predicts post-CABG AF and in-hospital mortality.</AbstractText>Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,505 | Cardiac arrest from postpartum spontaneous coronary artery dissection. | We present the case of a 32-year-old woman who presented to the emergency department with a witnessed cardiac arrest. She was otherwise healthy with no cardiac risk factors and had undergone an uneventful repeated cesarean section 3 days priorly. The patient underwent defibrillation, out of ventricular fibrillation to a perfusing sinus rhythm, and was taken to the catheterization laboratory where coronary angiography findings showed spontaneous dissection of the left anterior descending artery. The patient received a total of 6 stents during her hospital stay and was eventually discharged in good condition. Spontaneous coronary artery dissection is a rare entity with a predilection for pregnant or postpartum women. Early diagnosis and treatment are key for survival, and when identified early, mortality rate is reduced. |
14,506 | Shortened Ca2+ signaling refractoriness underlies cellular arrhythmogenesis in a postinfarction model of sudden cardiac death. | Diastolic spontaneous Ca(2+) waves (DCWs) are recognized as important contributors to triggered arrhythmias. DCWs are thought to arise when [Ca(2+)] in sarcoplasmic reticulum ([Ca(2+)](SR)) reaches a certain threshold level, which might be reduced in cardiac disease as a consequence of sensitization of ryanodine receptors (RyR2s) to luminal Ca(2+).</AbstractText>We investigated the mechanisms of DCW generation in myocytes from normal and diseased hearts, using a canine model of post-myocardial infarction ventricular fibrillation (VF).</AbstractText>The frequency of DCWs, recorded during periodic pacing in the presence of a β-adrenergic receptor agonist isoproterenol, was significantly higher in VF myocytes than in normal controls. Rather than occurring immediately on reaching a final [Ca(2+)](SR), DCWs arose with a distinct time delay after attaining steady [Ca(2+)](SR) in both experimental groups. Although the rate of [Ca(2+)](SR) recovery after the SR Ca(2+) release was similar between the groups, in VF myocytes the latency to DCWs was shorter, and the [Ca(2+)](SR) at DCW initiation was lower. The restitution of depolarization-induced Ca(2+) transients, assessed by a 2-pulse protocol, was significantly faster in VF myocytes than in controls. The VF-related alterations in myocyte Ca(2+) cycling were mimicked by the RyR2 agonist, caffeine. The reducing agent, mercaptopropionylglycine, or the CaMKII inhibitor, KN93, decreased DCW frequency and normalized restitution of Ca(2+) release in VF myocytes.</AbstractText>The attainment of a certain threshold [Ca(2+)](SR) is not sufficient for the generation of DCWs. Postrelease Ca(2+) signaling refractoriness critically influences the occurrence of DCWs. Shortened Ca(2+) signaling refractoriness due to RyR2 phosphorylation and oxidation is responsible for the increased rate of DCWs observed in VF myocytes and could provide a substrate for synchronization of arrhythmogenic events at the tissue level in hearts prone to VF.</AbstractText> |
14,507 | Contact force-controlled zero-fluoroscopy catheter ablation of right-sided and left atrial arrhythmia substrates. | Conventional catheter ablation of cardiac arrhythmias is associated with radiation risks for patients and laboratory personnel. However, nonfluoroscopic catheter guidance may increase the risk for inadvertent cardiac injury. A novel radiofrequency ablation catheter capable of real-time tissue-tip contact force measurements may compensate for nonfluoroscopic safety issues.</AbstractText>To investigate the feasibility of contact force-controlled zero-fluoroscopy catheter ablation.</AbstractText>In 30 patients (including 12 pediatric patients), zero-fluoroscopy catheter ablation of right-sided (right atrium, n = 20; right ventricle, n = 2) and left atrial (n = 8) arrhythmias was attempted. Inclusion criteria were symptomatic suspected atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, focal right atrial and ventricular arrhythmias, and lone atrial fibrillation. A novel irrigated-tip catheter with an integrated contact force sensor was used for nonfluoroscopic 3-dimensional electroanatomical mapping and radiofrequency ablation. Transseptal access was gained under transesophageal guidance for ablation of left-sided arrhythmias.</AbstractText>Procedural success without fluoroscopy was achieved in 29 of the 30 patients (97%). In 1 patient, endocardial nonfluoroscopic ablation failed because of an epicardial accessory pathway within a coronary sinus aneurysm. Mean total contact force and amplitude of force undulations were kept below 50 g during mapping and below 40 g during ablation to prevent contact force peaks (>100 g). Apart from a transient second-degree type I atrioventricular block, no complications occurred. The mean procedure time was 2.8 ± 0.9 hours. There were no arrhythmia recurrences during a mean follow-up of 6.2 ± 4.2 months.</AbstractText>Contact force-controlled zero-fluoroscopy catheter ablation is generally feasible in right-sided and left atrial cardiac arrhythmias.</AbstractText>Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,508 | Ischemia-modified albumin use as a prognostic factor in coronary bypass surgery. | Various types of markers have been used so far in order to reveal myocardial perfusion defect. However, these markers usually appear in the necrosis phase or in the late stage. Having been the focus of various investigations recently, ischemia-modified albumin (IMA) is helpful in establishing diagnosis in the early stages of ischemia, before necrosis develops.</AbstractText>30 patients that underwent only coronary bypass surgery due to ischemic heart disease within a specific period of time have been included in the study. IMA levels were studied in the preoperative, intraoperative, and postoperative periods. The albumin cobalt binding assay was used for IMA determination. Hemodynamic parameters (atrial fibrillation, the need for inotropic support, ventricular arrhythmia) of the patients in the postoperative stage were evaluated. Intraoperative measurement values (mean ± SD) of IMA (0.67677 ± 0.09985) were statistically significantly higher than those in the preoperative (0.81516 ± 0.08894) and postoperative (0.70477 ± 0.07523) measurements. Considering atrial fibrillation and need for inotropics, a parallelism was detected with the levels of IMA.</AbstractText>IMA is an early-rising marker of cardiac ischemia and enables providing a direction for the treatment at early phases.</AbstractText> |
14,509 | Height and risk of heart failure in the Physicians' Health Study. | Although previous studies have reported an association between height and cardiovascular disease, it is unclear whether height is associated with the risk of heart failure (HF). We hypothesized that height would be inversely associated with HF risk. We used prospective data from 22,042 male physicians (mean age 53.8 years) from the Physicians' Health Study. Height was self-reported at baseline. Incident HF was ascertained using follow-up questionnaires and validated through review of the medical records in a subsample. The Cox proportional hazard model was used to compute the hazard ratio (HR) and corresponding 95% confidence interval (CI). The mean height ± SD was 1.78 ± 0.07 m. A total of 1,444 HF cases occurred during a mean follow-up of 22.3 years. Compared to subjects in the lowest height category (1.40 to 1.73 m), the HR for HF was 0.86 (95% CI 0.74 to 0.99), 0.82 (95% CI 0.70 to 0.95), and 0.76 (95% CI 0.63 to 0.91) for the height categories of 1.74 to 1.78 m, 1.79 to 1.83 m, and 1.84 to 2.08 m, respectively, after adjustment for age, weight, hypertension, and diabetes mellitus (p for trend = 0.0023). The HR per SD increment in height was 0.92 (95% CI 0.86 to 0.98) in a fully adjusted model. The exclusion of those with prevalent atrial fibrillation, left ventricular hypertrophy, valvular heart disease, and a history of coronary artery bypass grafting yielded similar results (HR per SD 0.88, 95% CI 0.83 to 0.94). In conclusion, our data demonstrated an inverse association between height and incident HF in United States male physicians. Additional studies to elucidate the underlying biologic mechanisms are warranted. |
14,510 | Progressive conduction defects and cardiac death in late infantile neuronal ceroid lipofuscinosis. | This article reports the case of a female with late infantile neuronal ceroid lipofuscinosis who developed right and left anterior bundle branch blocks and episodic bradycardia at 23 years of age. Several episodes of supraventricular tachycardia manifested at 23 and 27 years of age. In addition, a transient second-degree atrioventricular conduction block also emerged at 27 years of age. Atrial fibrillation and aggravation of the atrioventricular conduction block resulted in progressive bradycardia and cardiac death at the age of 28 years. Cardiac involvement and accumulation of lipopigments in the myocardium and cardiac conduction system have been recognized in juvenile neuronal ceroid lipofuscinosis, but this is the first report to describe progressive conduction defects in a case of late infantile neuronal ceroid lipofuscinosis. |
14,511 | Left atrial size predicts the onset of atrial fibrillation after major pulmonary resections. | Atrial fibrillation (AF) is a frequent complication after pulmonary resections. Notwithstanding prevention and early treatment it may show a negative impact on the outcome. We assessed the role of echocardiographic variables to predict the onset of this complication.</AbstractText>One-hundred and thirty-four patients were prospectively evaluated: 72 (53.7%) (Group I) underwent lobectomy or pneumonectomy; 62 (46.3%) receiving minor thoracic procedures were included in Group II. Previous AF was the only exclusion criteria. All patients preoperatively underwent bidimensional echocardiography. Demographics, type of resection, histology, staging, diagnosis of chronic obstructive pulmonary disease , induction chemotherapy, smoking history, magnesium levels, other cardiologic diseases, electrocardiographic and echocardiographic findings (atrial and ventricular diameters, left atrial area, left ventricular ejection fraction and diastolic dysfunction) were assessed.</AbstractText>Preoperative variables did no't show any statistically significant difference between the groups. In 21 patients (15.7%) AF was observed 3.7 ± 1.8 days after surgery. All AF episodes occurred in Group I. Three patients (2.2%) with AF died during the postoperative course. The left atrial diameter and area were significantly enlarged in patients with AF (P = 0.001 and P < 0.0002); 18 AF episodes (86%) occurred in patients with atrial enlargement. At univariate analysis low postoperative magnesium levels, LV diastolic dysfunction, left atrial antero-posterior diameter >40 mm, left atrial area above 20 mm(2) and extended resections were statistically significant. At multivariate analysis only left atrial area enlargement was an independent predictive prognostic factor for postoperative AF.</AbstractText>Echocardiographic left atrial size evaluation may be useful to predict the onset of postoperative AF in patients undergoing lobectomy and pneumonectomy.</AbstractText> |
14,512 | Implantation of additional defibrillation lead into the coronary sinus: an effective method of decreasing defibrillation threshold. | We report a case of successful implantation of an additional defibrillation lead into the coronary sinus due to high defibrillation threshold (DFT) in a seriously ill patient with a history of extensive myocardial infarction referred for implantable cardioverter- defibrillator implantation after an episode of unstable ventricular tachycardia. All previous attempts to reduce DFT, including subcutaneous electrode implantation, had been unsuccessful. |
14,513 | The incidence and prognostic significance of cardiac arrhythmias and conduction abnormalities in patients with acute coronary syndromes and renal dysfunction. | The incidence of cardiac arrhythmias, including atrial fibrillation (AF) in chronic kidney disease, is unknown, although AF is several times more common in patients with end-stage kidney disease than in the general population.</AbstractText>To assess the incidence, types and management of cardiac arrhythmias and conduction abnormalities in patients with acute coronary syndromes (ACS) and renal dysfunction. We also evaluated the prognostic significance of arrhythmias in this patient group.</AbstractText>We analysed 86 patients with renal dysfunction (GFR < 60 mL/min) out of 1005 patients hospitalised in our department between 2008 and 2009 for unstable angina and ST-elevation and non-ST-elevation myocardial infarction.</AbstractText>Cardiac arrhythmias were observed in 44 (51.1%) patients with AF being the most common (27 patients, 31.4%), predominantly in the paroxysmal form (21.4%). A total of 14 (16.3%) patients had cardiac arrhythmias requiring temporary or permanent pacing. Only 4 (4.6%) patients showed transient conduction abnormalities due to hyperkalaemia in the course of renal failure, while the remaining 10 (11.6%) patients demonstrated conduction abnormalities due to ACS. A total of 3 (3.5%) patients had other arrhythmias (atrial tachycardia, ventricular arrhythmias). During the follow-up period (mean duration: 14.3 months) 7 out of 44 patients (15.9%) with renal dysfunction and arrhythmia and 2 out of 42 patients (4.7%) without arrhythmia died (p < 0.05).</AbstractText>Cardiac arrhythmias occur more often in patients with ACS if renal dysfunction is also present and are associated with poor prognosis.</AbstractText> |
14,514 | Altered trans-mitral flow velocity pattern after exercise predicts development of new-onset atrial fibrillation in elderly patients with impaired left ventricular relaxation at rest: prognostic value of diastolic stress echocardiography. | This study attempted to determine whether exercise induced left ventricular (LV) diastolic dysfunction estimated by altered trans-mitral flow (TMF) velocity pattern after exercise is associated with increased risk of cardiac events including new-onset atrial fibrillation (AF) in elderly patients with impaired LV relaxation at rest.</AbstractText>Diastolic stress echocardiography has been applied to evaluate LV diastolic function during and post-exercise. Prognostic importance of exercise-induced diastolic dysfunction remains uncertain.</AbstractText>We studied 126 patients (70±5 years; 70 males) who underwent treadmill stress echocardiography. Doppler measurements were done before exercise and immediately after the post-stress image acquisition, and the ratio between early (E) and atrial (A) TMF velocities was measured. Patients with impaired LV relaxation (E/A<1.0) at rest were studied. Altered TMF velocity pattern was present when patients with E/A<1.0 at rest developed E/A≥1.0 after exercise. Primary endpoints for follow-up were combination of major cardiac events and new-onset AF.</AbstractText>There were 42 patients with altered TMF velocity pattern after exercise. During the 5-year follow-up period, there were 30 cardiac events including 13 new-onset AF. Kaplan-Meier survival plot demonstrated that altered TMF velocity pattern after exercise is associated with increased risk of cardiac events (p<0.0001) including development of new-onset AF (p=0.0003). Cox hazard ratio analysis demonstrated that altered TMF velocity pattern after exercise was the best predictor of cardiac events (hazard ratio 3.939; 95%confidence interval 1.662-9.337; p=0.0018).</AbstractText>Altered TMF velocity pattern after exercise provides significant prognostic information for predicting cardiac events including new-onset AF in elderly patients with impaired left ventricular relaxation at rest.</AbstractText>Copyright © 2011 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.</CopyrightInformation> |
14,515 | Risk of malignant arrhythmias in initially symptomatic patients with Wolff-Parkinson-White syndrome: results of a prospective long-term electrophysiological follow-up study. | The available amount of detailed long-term data in patients with Wolff-Parkinson-White syndrome is limited, and no prospective electrophysiological studies looking at predictors of malignant arrhythmia are available.</AbstractText>Among 8575 symptomatic Wolff-Parkinson-White patients with atrioventricular reentrant tachycardia referred for electrophysiological test, 369 (mean age, 23±12.5 years) declined catheter ablation and were followed up. The primary end point of the study was to evaluate over a 5-year follow-up the predictors and characteristics of patients who develop malignant arrhythmias. After a mean follow-up of 42.1±10 months, malignant arrhythmias developed in 29 patients (mean age, 13.9±5.6 years; 26 male), resulting in presyncope/syncope (25 patients), hemodynamic collapse (3 patients), or cardiac arrest caused by ventricular fibrillation (1 patient). Of the remaining 340 patients, 168 (mean age, 34.2±9.0 years) remained asymptomatic up to 5 years, and 172 (mean age, 13.6±5.1 years) had benign recurrence, including sustained atrioventricular reentrant tachycardia (132 patients) or atrial fibrillation (40 patients). Compared with the group with no malignant arrhythmias, the group with malignant arrhythmias showed shorter accessory-pathway effective refractory period (P<0.001) and more often exhibited multiple accessory pathways (P<0.001), and atrioventricular reentrant tachycardia triggering sustained pre-excited atrial fibrillation was more frequently inducible (P<0.001). Multivariable analysis demonstrated that short accessory-pathway effective refractory period (P<0.001) and atrioventricular reentrant tachycardia triggering sustained pre-excited atrial fibrillation (P<0.001) were independent predictors of malignant arrhythmias.</AbstractText>Symptomatic patients with Wolff-Parkinson-White syndrome generally have a good outcome, and predictors of malignant arrhythmias are similar to those reported for asymptomatic patients with ventricular pre-excitation.</AbstractText> |
14,516 | [Venous thrombosis secondary to catheter insertion for hypothermia after cardiac arrest. Report of one case]. | To improve survival and reduce neurological injury, the use of mild hypothermia following cardiac arrest has been recommended. We report a 65 years old woman who presented an out-of-hospital ventricular fibrillation and cardiac arrest. The patient was comatose following initial resuscitation and was admitted into the ICU, where cooling was initiated using an intravascular catheter. After 48 hours, rewarming was initiated. Although no neurological impairment was observed, physical examination of the right inguinal area and echo-Doppler examination revealed an extensive catheter-related thrombophlebitis with right ileocaval vein occlusion., with high risk of massive and life threatening pulmonary embolism. We report a clinical case and review the literature to point out the need for a high index of diagnostic suspicion of deep venous thrombosis in these specific setting. |
14,517 | Simultaneous Doppler tracing of transmitral inflow and mitral annular velocity as an estimate of elevated left ventricular filling pressure in patients with atrial fibrillation. | The time interval between the onset of early transmitral flow velocity (E) and that of early diastolic mitral annular velocity (e') (T(E-e')) is a good predictor of elevated left ventricular (LV) filling pressure in patients with sinus rhythm. Although the evaluation of LV filling pressure using E/e' has been challenging in atrial fibrillation (AF), the usefulness of T(E-e') is unknown.</AbstractText>E and e' were simultaneously recorded using dual Doppler echocardiography in 45 AF patients (30 men; mean age, 69 ± 9 years). E/e' and T(E-e') were calculated and compared with the pulmonary capillary wedge pressure (PCWP), which was measured invasively. E/e' and T(E/e') correlated with PCWP (E/e', r=0.57, P<0.001; T(E-e'), r=0.77, P<0.001). Using receiver operating characteristic analysis, the optimal cut-off for T(E-e') was 34 ms (sensitivity, 95%; specificity, 88%) and that for E/e' was 14.6 (sensitivity, 50%; specificity, 84%) in order to predict >12-mmHg PCWP. When the combined cut-offs of T(E-e') >34 ms and E/e' >14.6 were used, the sensitivity and specificity of predicting elevated PCWP were improved to 100% and 88%, respectively.</AbstractText>In AF patients, the simultaneous recording of E and e' using dual Doppler echocardiography and the analysis of T(E-e'), in addition to E/e', improved the accuracy of evaluation of LV filling pressure.</AbstractText> |
14,518 | J-wave-associated ventricular fibrillation in a patient with a subarachnoid haemorrhage. | We report a case of 59-year-old man with subarachnoid haemorrhage (SAH) complicated by ventricular fibrillation (VF). Continuous electrocardiogram monitoring revealed that J-waves appeared immediately before the VF. The present report is the first to describe a J-wave-associated VF as another possible mechanism of sudden cardiac death in patients with SAH. |
14,519 | Does appropriate treatment of the primary underlying cause of PEA during resuscitation improve patients' survival? | We aimed to document how often patients received appropriate treatment of the primary cause underlying pulseless electrical activity (PEA) during cardiopulmonary resuscitation (CPR) and how it affected their outcome.</AbstractText>Data were collected between 2003 and 2010 in Finland and Sweden. All adult patients who underwent in-hospital cardiac arrest (IHCA) with PEA as the initial rhythm were included, if CPR was attempted. Patients were divided into two groups: those who received appropriate treatment of the primary cause during CPR (treatment of the primary cause group) and those who received conventional CPR (non-specific treatment group). Survival between groups was compared and a multivariable logistic regression analysis was performed to exclude the effect of possible confounders.</AbstractText>Of 104 study patients, 19 (18%) received treatment of the primary cause and 85 (82%) received non-specific treatment. 30-Days survival of patients in treatment of primary cause group was superior compared to patients in the non-specific treatment group: 6 (32%) vs. 9 (11%) were alive 30 days after IHCA, p=0.03. Multivariable analysis suggested that treatment of the primary cause improves the odds of survival 2.5-fold, but this was not statistically significant. Age was the only significant independent prognostic factor for 30-days survival.</AbstractText>During CPR, only a fifth of patients received appropriate treatment of the primary cause underlying PEA. Those patients were more likely to be alive 30 days after IHCA, but age turned out to be the only significant individual factor for better survival.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,520 | [Circadian rhythm and time variations in out-hospital sudden cardiac arrest]. | To analyze the chronobiological and time variations of out- hospital cardiac arrest (OHCA).</AbstractText>A retrospective descriptive study was made.</AbstractText>All cases of OHCA of cardiac origin registered over 18 months in the database of the emergency medical service (EMS) of the Autonomous Community of Castilla y León (Spain) were evaluated. VARIABLES ANALYZED: Age, sex, recovery of spontaneous circulation (ROSC), first monitored rhythm (amenable / not amenable to defibrillation), alert site [(home, public place, primary care (PC) center], alerting person (family, witness, law enforcement member, PC center staff), alert time (0-8; 8-16; 16-24), emergency team activation time, care time and day of the week. Univariate analysis (chi-squared), variance, and nonparametric tests comparing the variables in three periods of 8 hours. Chronobiological analysis by fast Fourier transform and Cosinor testing.</AbstractText>We studied 1286 cases reported between January 2007 and June 2008. Statistically significant differences were observed in terms of younger age, higher incidence in the victim's home, and greater frequency of family-cohabiting persons as witnesses in the period between 0 and 8 hours. Chronobiological analysis found daily rhythm (circadian) with acrophase at 11.16 h (p<0.001) and weekly rhythm (circaseptan) with acrophase on Wednesday (p<0.05). The median alert time-care time interval and emergency team activation time-care time were 11.7 min and 8.0 min, respectively, without differences between periods.</AbstractText>We have demonstrated the presence of a daily rhythm of emergence of OHCA with a morning peak and a weekly rhythm with a peak on Wednesdays. These results can guide the planning of resources and improvements in response in certain time periods.</AbstractText>Copyright © 2011 Elsevier España, S.L. and SEMICYUC. All rights reserved.</CopyrightInformation> |
14,521 | Shock advisory system with minimal delay triggering after end of chest compressions: accuracy and gained hands-off time. | Shortening hands-off intervals can improve benefits from defibrillation. This study presents the performance of a shock advisory system (SAS), which aims to decrease the pre-shock pauses by triggering fast rhythm analysis at minimal delay after end of chest compressions (CC).</AbstractText>The SAS is evaluated on a database of 1301 samples from 311 out-of-hospital cardiac arrests (OHCA) from automated external defibrillators (AEDs). The following rhythms are identified: 788 asystoles (ASYS), 20 normal sinus rhythms (NSR), 394 other non-shockable rythms (ONS), 81 ventricular fibrillations (VF), 18 rapid ventricular tachycardias (VThi). SAS is launched in two-stages: first stage for accurate detection of actual end of CC (ReEoCC); second stage for early "Shock"/"No-Shock" decision by using all available artifact-free ECG signals after REoCC during 3, 5, 7 s.</AbstractText>Performance of the presented SAS versus AEDs is compared. The median hands-off time gained from earlier starting of ECG analysis is 5.8 s and for earlier shock advice is 12.5 s to 8.5 s when SAS rhythm analysis lasts 3 s to 7 s. The SAS accuracy at 3-7 s is: specificity 97.7-98.9% (ASYS), 100-100% (NSR), 98.5-99.2% (ONS); sensitivity 91.4-98.8% (VF), 88.9-96.7% (VThi).</AbstractText>This study indicates that shortening the pre-shock hands-off pause by more efficient management of the SAS process in AEDs is possible. For analysis duration of 5 s (7 s), the delay between the end of chest compressions and the shock advice can be reduced by 10.5 s (8.5 s) median, while AHA requirements for rhythm detection accuracy are met. The use of this solution in AEDs could provide more reliable rhythm analysis than methods applying filtering techniques during CC.</AbstractText>Copyright © 2011 Elsevier B.V. All rights reserved.</CopyrightInformation> |
14,522 | Delayed high-quality CPR does not improve outcomes. | The quality of cardiopulmonary resuscitation (CPR) is an important factor in the outcome of cardiac arrest. Our objective was to compare outcomes following either immediate low-quality (LQ) CPR or delayed high-quality (HQ) CPR. We hypothesized that delayed HQ CPR will improve the outcomes of CPR in comparison to immediately performing LQ CPR.</AbstractText>Eighteen Sprague-Dawley rats were randomized into two groups: (1) Delayed HQ CPR (HQ group, n = 9). (2) Immediate LQ CPR (LQ group, n = 9). Ventricular fibrillation (VF) was induced and untreated for 8 mins. CPR was immediately performed in LQ group for 5 mins. Compression depth was set at 70% of the "optimal compression depth". VF was untreated for an additional 5 mins in HQ group. HQ CPR was started together with ventilation (100% oxygen) and external hypothermia for 8 mins in both groups. The "optimal compression depth" was approximately 30% of the anteroposterior chest diameter. Epinephrine was administrated 3 mins prior to defibrillation attempt. Restoration of spontaneous circulation, postresuscitation myocardial function and survival time were monitored.</AbstractText>All animals in the LQ group and 7 of 9 animals in the HQ group were resuscitated. Myocardial function, including ejection fraction and cardiac output was better in the LQ group than in the HQ group (p < 0.05) and survival time was longer in the LQ group (p < 0.05).</AbstractText>The outcomes after immediate LQ CPR, were better than those after delayed HQ CPR in this rat model of cardiac arrest and resuscitation.</AbstractText>Copyright © 2011 Elsevier B.V. All rights reserved.</CopyrightInformation> |
14,523 | Sodium nitroprusside enhanced cardiopulmonary resuscitation prevents post-resuscitation left ventricular dysfunction and improves 24-hour survival and neurological function in a porcine model of prolonged untreated ventricular fibrillation. | Sodium nitroprusside-enhanced CPR, or SNPeCPR, consists of active compression-decompression CPR with an impedance threshold device, abdominal compression, and intravenous sodium nitroprusside (SNP). We hypothesize that SNPeCPR will improve post resuscitation left ventricular function and neurological function compared to standard (S) CPR after 15 min of untreated ventricular fibrillation in a porcine model of cardiac arrest.</AbstractText>Pigs (n = 22) anesthetized with isoflurane underwent 15 min of untreated ventricular fibrillation, were then randomized to 6 min of S-CPR (n = 11) or SNPeCPR (n = 11) followed by defibrillation. The primary endpoints were neurologic function as measured by cerebral performance category (CPC) score and left ventricular ejection fraction.</AbstractText>SNPeCPR increased 24-hour survival rates compared to S-CPR (10/11 versus 5/11, p = 0.03) and improved neurological function (CPC score 2.5 ± 1, versus 3.8 ± 0.4, respectively, p = 0.004). Left ventricular ejection fractions at 1, 4 and 24 hours after defibrillation were 72 ± 11, 57 ± 11.4 and 64 ± 11 with SNPeCPR versus 29 ± 10, 30 ± 17 and 39 ± 6 with S-CPR, respectively (p < 0.01 for all).</AbstractText>In this pig model, after 15 min of untreated ventricular fibrillation, SNPeCPR significantly improved 24-hour survival rates, neurologic function and prevented post-resuscitation left ventricular dysfunction compared to S-CPR.</AbstractText>Copyright © 2011 Elsevier B.V. All rights reserved.</CopyrightInformation> |
14,524 | Optimizing the duration of CPR prior to defibrillation improves the outcome of CPR in a rat model of prolonged cardiac arrest. | This study was to investigate whether optimal duration of CPR prior to defibrillation could be guided by Amplitude Spectrum Analysis (AMSA) in the setting of prolonged VF on outcome of CPR.</AbstractText>VF was induced in thirty Sprague-Dawley rats and untreated for 8 minutes. Animals were then randomized into 3 groups prior to CPR: The duration of CPR prior to defibrillation was guided by AMSA (CC+AMSA); guidelines-based with delayed defibrillation that simulated the AED algorithm (GL+AED); and guidelines-based with immediate shock (GL+shock ready).</AbstractText>Regardless of groups, the majority of the animals (85%) required over 5 min of CPR to achieve restoration of spontaneous circulation (ROSC). Significantly greater rate of ROSC after first defibrillation (70% vs 0%, p < 0.01), lesser CPR interruptions and the number of defibrillations were observed in the CC+AMSA group when compared to both guidelines-based groups (p < 0.001). This was associated with a significantly better post-resuscitation myocardial and neurological function and longer durations of survival.</AbstractText>After prolonged VF, optimal duration of CPR prior to defibrillation guided by AMSA improves the outcome of CPR.</AbstractText>Copyright © 2011 Elsevier B.V. All rights reserved.</CopyrightInformation> |
14,525 | Prevalence and hemodynamic effects of leaning during CPR. | Cardiopulmonary resuscitation (CPR) guidelines recommend complete release between chest compressions (CC).</AbstractText>Evaluate the hemodynamic effects of leaning (incomplete chest wall release) during CPR and the prevalence of leaning during CPR.</AbstractText>In piglet ventricular fibrillation cardiac arrests, 10% and 20% (1.8 kg and 3.6 kg, respectively), leaning during CPR increased right atrial pressures, decreased coronary perfusion pressures, and decreased cardiac index and left ventricular myocardial blood flow by nearly 50%. In contrast, residual leaning of a 260 g accelerometer/force feedback device did not adversely affect cardiac index or myocardial blood flow. Among 108 adult in-hospital CPR events, leaning ≥ 2.5 kg was demonstrable in 91% of the events and 12% of the evaluated CC. For 12 children with in-hospital CPR, 28% of CC had residual leaning ≥ 2.5 kg and 89% had residual leaning ≥ 0.5 kg.</AbstractText>Leaning during CPR increases intrathoracic pressure, decreases coronary perfusion pressure, and decreases cardiac output and myocardial blood flow. Leaning is common during CPR.</AbstractText>Copyright © 2011 Elsevier B.V. All rights reserved.</CopyrightInformation> |
14,526 | The role of the renin-angiotensin system blocking in the management of atrial fibrillation. | To review current available evidence for the role of renin-angiotensin system blockade in the management of atrial fibrillation.</AbstractText>We conducted a PubMed and Medline literature search (January 1980 through July 2011) to identify all clinical trials published in English concerning the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers for primary and secondary prevention of atrial fibrillation. We also discussed renin-angiotensin system and its effects on cellular electrophysiology.</AbstractText>The evidence from the current studies discussed does not provide a firm definitive indication for the use of angiotensin converting enzyme inhibitors or angiotensin II receptor blockers in the primary or secondary prevention of atrial fibrillation. Nevertheless, modest benefits were observed in patients with left ventricular dysfunction. In view of the possible benefits and the low incidence of side-effects with angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, they can be given to patients with recurrent AF, specifically those with hypertension, heart failure and diabetes mellitus.</AbstractText> |
14,527 | Function of the CaMKII-ryanodine receptor signaling pathway in rabbits with left ventricular hypertrophy and triggered ventricular arrhythmia. | Calcium calmodulin-dependent kinase II (CaMKII) can be more active in patients with left ventricular hypertrophy (LVH), which in turn causes phosphorylation of ryanodine receptors, resulting in inactivation and the instability of intracellular calcium homeostasis. The present study aimed to determine the effect of CaMKII-ryanodine receptor pathway signaling in rabbits with left ventricular hypertrophy and triggered ventricular arrhythmia.</AbstractText>Forty New Zealand rabbits were randomized into four groups (10 per group): sham group, LVH group, KN-93 group (LVH+KN-93), and ryanodine group (LVH+ryanodine). Rabbits in the LVH, KN-93, and ryanodine groups were used to establish a left ventricular hypertrophy model by the coarctation of the abdominal aorta, while those in the sham group did not undergo the coarctation. After eight weeks, action potentials (APs) were recorded simultaneously in the endocardium and epicardium, and a transmural electrocardiogram (ECG) was also recorded in the rabbit left ventricular wedge model. Drugs were administered to the animals in the KN-93 and ryanodine groups, and the frequency of triggered APs and ventricular tachycardia was recorded after the rabbits were given isoprenaline (1 μmol/L) and high-frequency stimulation.</AbstractText>The frequency (animals/group) of triggered APs was 0/10 in the sham group, 10/10 in the LVH group, 4/10 in the KN-93 group, and 1/10 in the ryanodine group. The frequencies of ventricular tachycardia were 0/10, 9/10, 3/10, and 1/10, respectively. The frequencies of polymorphic ventricular tachycardia or ventricular fibrillation were 0/10, 7/10, 2/10, and 1/10, respectively. The frequencies of triggered ventricular arrhythmias in the KN-93 and ryanodine groups were much lower than those in the LVH group (P<0.05).</AbstractText>KN-93 and ryanodine can effectively reduce the occurrence of triggered ventricular arrhythmia in rabbits with LVH. The CaMKII-ryanodine signaling pathway can be used as a new means of treating ventricular arrhythmia.</AbstractText> |
14,528 | Effect of hypertransfusion on the gastrointestinal tract after cardiac arrest in a porcine model. | This study aimed to determine the potential protective effect of inducing hypertransfusion to the gastrointestinal tract following a porcine model of cardiac arrest and cardiopulmonary resuscitation (CPR) by evaluating the influence of gastrointestinal ultrastructure, ATPase and serum diamine oxidase.</AbstractText>Ventricular fibrillation was induced by programmed electrical stimulation in 16 male domestic pigs (n=8/group). Four minutes after ventricular fibrillation, CPR was performed. The pigs that successfully restored spontaneous circulation received intravenous infusion of either norepinephrine to maintain the mean arterial pressure at 130% of the baseline before ventricular fibrillation or normal saline. Serum diamine oxidase and gastrointestinal ATPase activity were determined, and histopathological examination of the gastrointestinal tract was performed by light and electron microscopy.</AbstractText>CPR caused significant injury to the gastrointestinal tract, elevating serum diamine oxidase and causing destruction of intestinal microvillus in control animals. Na(+)-K(+) ATPase and Ca(2+) ATPase activity in gastric tissue were significantly elevated in animals receiving hypertransfusion treatment compared with the control animals. Hypertransfusion also significantly reduced serum diamine oxidase to below control levels after CPR. Moreover, severe injury sustained by the gastrointestinal tissue was markedly ameliorated under hypertransfusion conditions compared with the control animals.</AbstractText>Gastrointestinal injury and abnormal energy metabolism were strikingly evident following CPR. Hypertransfusion inducing hypertension can improve energy metabolism and ameliorate gastrointestinal mucosal injury, indicating that hypothermia significantly ameliorates gastrointestinal injury sustained following cardiac arrest.</AbstractText> |
14,529 | Biventricular noncompaction cardiomyopathy in a patient presenting with new onset seizure: case report. | Ventricular noncompaction (VNC) of the myocardium is a rare genetic cardiomyopathy caused by a disorder during endocardial morphogenesis and could be accompanied by life-threatening complications. The major clinical manifestations of VNC are heart failure, arrhythmias, and embolic events. The left ventricle is the most commonly reported affected site, but a few cases of right ventricular involvement have also been reported. We report a case of biventricular noncompaction cardiomyopathy in a 31-year-old woman presenting with a new onset seizure. On the second day of her telemetry-monitored hospitalization, she suffered a witnessed ventricular fibrillation arrest requiring emergency direct-current cardioversion and induced hypothermia. Transthoracic echocardiography (TTE) showed isolated left ventricular (LV) noncompaction and depressed LV systolic function. Subsequent cardiac magnetic resonance imaging (MRI) revealed both left and right ventricular noncompaction. This unusual presentation highlights the importance of a complete and thorough evaluation of patients even when presenting with apparently noncardiac symptom(s). |
14,530 | A comparison of verapamil and digoxin for heart rate control in atrial fibrillation. | Atrial fibrillation (AF) is one of the most common types of sustained dysrhythmia and there are some disagreements about its treatment. The goals of AF treatment include the control of ventricular rate, the establishment of sinus rhythm and the prevention of thromboembolic events. In this study, the effect of verapamil was compared to digoxin on heart rate control in patients with AF.</AbstractText>This descriptive study was conducted in an emergency department (ED) in Iran. Sixty patients with a new onset AF and rapid ventricular response receiving digoxin or verapamil were included and observed.</AbstractText>Two thirty-patient groups receiving verapamil or digoxin were evaluated. The heart rate was significantly decreased in both groups (p = 0.002); however, the cardioversion was not noticed in both of them. The best rate control in verapamil and digoxin groups was observed after 5.9 mg (46.7%) and 0.6 mg (36.7%), respectively.</AbstractText>Administration of verapamil in comparison with digoxin has no difference to control the heart rate in AF patients. It should be taken into consideration that prospective randomized studies should be conducted to identify the efficacy and select the best of these two drugs to treat AF patients.</AbstractText> |
14,531 | Zero flow global ischemia-induced injuries in rat heart are attenuated by natural honey. | In the present study, effects of preischemic administration of natural honey on cardiac arrhythmias and myocardial infarction size during zero flow global ischemia were investigated in isolated rat heart.</AbstractText>The isolated hearts were subjected to 30 min zero flow global ischemia followed by 120 min reperfusion then perfused by a modified drug free Krebs-Henseleit solution throughout the experiment (control) or the solution containing 0.25, 0.5, 1 and 2% of natural honey for 15 min before induction of global ischemia (treated groups), respectively. Cardiac arrhythmias were determined based on the Lambeth conventions and the infarct size was measured by computerized planimetry.</AbstractText>Myocardial infarction size was 55.8±7.8% in the control group, while preischemic perfusion of honey (0.25, 0.5, 1 and 2%) reduced it to 39.3±11, 30.6±5.5 (P<0.01), 17.9±5.6 (P<0.001) and 8.7±1.1% (P<0.001), respectively. A direct linear correlation between honey concentrations and infarction size reduction was observed (R(2)=0.9948). In addition, total number of ventricular ectopic beats were significantly decreased by all used concentrations of honey (P<0.05) during reperfusion time. Honey (0.25, 0.5 and 1 %) also lowered incidence of irreversible ventricular fibrillation (P<0.05). Moreover, number and duration of ventricular tachycardia were reduced in all honey treated groups.</AbstractText>Preischemic administration of natural honey before zero flow global ischemia can protect isolated rat heart against ischemia/reperfusion injuries as reduction of infarction size and arrhythmias. Maybe, antioxidant and free radical scavenging activities of honey, reduction of necrotized tissue and providing energy sources may involve in these cardioprotective effects of honey.</AbstractText> |
14,532 | Stroke prevention in atrial fibrillation: latest clinical trials and guidelines. | Atrial Fibrillation (AF) is the most common sustained arrhythmia and 1/6 strokes is attributed to AF. The cornerstone of treatment remains maintaining sinus rhythm or appropriate ventricular rate control in addition to prevention of stroke. Oral anticoagulation therapy (OAC) with vitamin K antagonists (VKAs) has been the gold standard for almost 50 years and a significant reduction in the risk of stroke in patients with AF has been demonstrated. Nonetheless, only 50% of patients with guideline recommendations for OAC treatment actually receive VKAs and half of these will discontinue therapy within 3 to 5 years with only another half achieving therapeutic ranges more than 50% of the time. The aforementioned limitations in addition with frequent blood monitoring have prompted the development of a series of new OAC therapies. The present review focuses on the current pharmacological management for stroke prevention in patients with AF based on current and emerging evidence. |
14,533 | Contrast media injection into right coronary artery caused thrombus extraction to aorta that may have resulted in left main trunk thrombosis. | A 59-year-old man with inferior acute myocardial infarction underwent an urgent coronary angiography and as a result a total occlusion of the ostial right coronary artery (RCA) was observed. Interestingly, the thrombus in the RCA clearly shortened within 2.3 s during the contrast media injection. While we prepared for percutaneous coronary intervention (PCI) of the RCA, ventricular fibrillation occurred and pulseless electrical activity continued in spite of repeated cardioversion. Despite no stenosis in the left main trunk (LMT) in the initial coronary angiography, the LMT was totally occluded. Following aspiration therapy on the LMT with percutaneous cardiopulmonary support, PCI of the RCA was performed. A coronary angiography should be carefully performed if a lot of thrombi exist in the coronary ostium because LMT embolism may have been caused by thrombus extraction from the RCA by contrast media injection. |
14,534 | To cool or not to cool during cardiopulmonary resuscitation. | Therapeutic hypothermia following cardiac arrest improves neurologic outcome following adult ventricular fibrillation (VF) cardiac arrest and perinatal hypoxic ischemic encephalopathy. Evaluation of therapeutic hypothermia in the pediatric cardiac arrest population has been limited thus far to retrospective evaluations and to date there have been no published prospective efficacy trials. Two retrospective pediatric cohort studies showed no benefit from hypothermia compared to usual care. The timing (intra-arrest or post-arrest) and duration of hypothermia may impact patient outcome. While overshoot hypothermia <32°C, hypokalemia, and bradycardia are commonly associated with induced hypothermia, the risks of severe arrhythmia and bleeding are no worse than in normothermic controls. Despite this, rewarming has been identified as a vulnerable time for hypotension and seizure activity and may attribute to worse outcome. The American Heart Association's current recommendation is "therapeutic hypothermia (32-34°C) may be considered for children who remain comatose after resuscitation from cardiac arrest. It is reasonable for adolescents resuscitated from sudden, witnessed, out-of-hospital VF cardiac arrest." Ongoing research will help delineate whether induced hypothermia following pediatric cardiac arrest improves neurologic outcome. |
14,535 | Coronary air embolism during removal of a central venous catheter. | Acute air embolism has been described during central venous cannulation, but it may also occur during catheter removal in a spontaneously breathing patient. We describe an episode of acute coronary ischaemia that occurred during CV catheter removal.</AbstractText>A 23-year-old male, multiple trauma patient was treated over 27 days in an ITU. He required a tracheostomy, two weeks of mechanical ventilation, and several surgical interventions. On the 27th day, he was scheduled to be transferred to a low-dependency area and his CVC was removed from the left subclavian vein. After five minutes, the pressure pad was released from the site of cannulation; the patient started coughing and became dyspnoeic. He developed tachyarrhythmia with ST depression in the 2nd, 3rd and aVF leads, followed by marked ST elevation, and subsequently, ventricular fibrillation. The patient was placed in the Trendelenburg position and CPR was started. Normal sinus rhythm returned after three defibrillations. Echocardiography revealed the presence of a large amount of air bubbles within the left ventricle, which disappeared spontaneously within one minute. The patient quickly regained consciousness and his condition returned to normal within 12 h, with transient elevation of heart enzymes. Five days later, he was decannulated and transferred to the orthopaedic ward in a satisfactory condition.</AbstractText>Air embolism during CV catheter removal is a rare event, but it may occur when a persistent tunnel remains after prolonged cannulation, associated with negative intrathoracic pressure created by a spontaneously breathing or coughing patient. In the case described, acute myocardial ischaemia occurred in the region supplied by the right coronary artery, which is located higher than the left one and is therefore more exposed to air bubbles. We could not demonstrate, however, the presence of a persistent foramen ovale, however some connection had to exist between the right and left sides of the heart in our patient.</AbstractText>Special caution should be exercised during CV catheter removal, and the procedure should be always done with the patient placed in the Trendelenburg position.</AbstractText> |
14,536 | [Sudden cardiac arrest in ventricular fibrillation mechanism as a first manifestation of primary mitral valve prolapse]. | We present the case of a 58 year-old patient with a primary mitral valve prolapse (MVP) at whose first manifestation of the disease was a sudden cardiac death (SCD) in ventricular fibrillation mechanism. In ECG paroxysmal atrial fibrillation was detected. The arrhythmia became persistent atrial fibrillation but in ECG sinus rhythm recording, QT dispersion occurred. In the echocardiography we found a classic MVP syndrome with large mitral regurgitation, preserved left ventricular systolic function and recent infective endocarditis features on posterior cusp of mitral valve. In the computed tomography of the head we found acute and recent history of stroke. The patient was qualified for implantable cardioverter-defibrillators (ICD) implantation as a secondary SCD preventive treatment. An artificial mitral valve was implanted. In the long-term observation (36 month) two adequate ICD interventions caused by ventricular tachycardia were recorded. General condition of the patient remains stable. |
14,537 | [Influence of increased mean heart rate at rest on mortality and ventricular tachycardia resulting in adequate intervention in patients after implantable cardioverter-defibrillator implantation]. | Increased heart rate at rest (HR) is a risk factor of sudden cardiac death (SCD) and cardiovascular mortality.</AbstractText>Retrospective assessment of increased HR influence on mortality and ventricular tachycardia followed by adequate ICD intervention.</AbstractText>350 patients (52 female, 298 male), mean age 65.1+/-10.1 years (22-89 years) with ICD without resynchronization function implanted between 2008 and 2010 were examined. ECGs at rest were used to determine HR. In case of atrial fibrillation, mean value of 2 shortest and longest RR intervals was calculated to determine HR.</AbstractText>During the mean observation period of 387+/-300 days, 73 patients (66 male, 7 female), mean age 63.7+/-12.2 years (22-89) had an arrhythmial/intervention, and 46 patients (9 male, 37 feamle), mean age 68.8+/-10.3 years (43-86) died. To optimize sensitivity and specificity of HR, cut off point was established using ROC curve (79/min). Number of patients with HR>79/min was significantly higher (64.7% vs 19,1%, p<0.022) in the group of patients with arrhyth-mialintervention vs no arrhythmial/intervention, and in dead vs alive patients (73.9% vs 19.5%, p<0,001). Kaplan-Meier univariate analysis proved, that HR<or =79/min was an important factor increasing probability of survival (p<0.001) and arrhythmial/intervention free live (p<0.012). HR>79/ min particularly predisposed to fast ventricular arrhythmias and interventions - CV (p<0.092). In Cox multivariate analysis, HR< or =79/min was a protective factor only in death risk (HR=0.2362, 95%CI=0.1094-0.5099, p<0.0002).</AbstractText>An important factor increasing probability of survival without ventricular arrhythmia or death was a mean heart rate below 79/min. The cycle length of the baseline rhythm determine the arrhythmia cycle length.</AbstractText> |
14,538 | Diagnostic utility of specific electrocardiographical parameters in predicting left ventricular function. | Changes in electrocardiography (ECG) parameters, including sinus tachycardia, atrial fibrillation, bundle branch blocks, Q waves and left ventricular (LV) hypertrophy, are commonly observed in patients with heart failure (HF).</AbstractText>To determine whether specific ECG parameters have a diagnostic role in predicting LV systolic dysfunction (LVSD) in patients with suspected HF.</AbstractText>A total of 123 patients with symptoms or signs of HF and 20 HF patients with New York Heart Association class IV status were consecutively recruited. Several ECG parameters, including QRS duration, dispersion and SV1 or SV2 + RV5 or RV6 ≥3.5 mV (Goldberger's first criterion), QRS amplitude ≤0.8 mV in the limb leads (Goldberger's second criterion) and RV4/SV4 <1 (Goldberger's third criterion), were subsequently determined and correlated with LV ejection fraction (LVEF).</AbstractText>One hundred six patients had LVEF <50% (LVSD group), while 37 patients had LVEF ≥50% (non-LVSD group). The maximal QRS duration of the LVSD group was significantly longer than that of the non-LVSD group (124.5±20.8 ms versus 109.7±13.1 ms; P<0.001). ROC analysis revealed that a cut-off point of QRS duration ≥124 ms significantly predicted LVSD (OR 4.1 [95% CI 1.7 to 10.2]; P=0.001). The frequencies of Goldberger's first and third criteria were higher in the LVSD group (OR 8.3 [95% CI 1.9 to 36.4]; P=0.001; and OR 8.9 [95% CI 3.4 to 23.2]; P<0.001, respectively). Logistic regression analysis showed that Goldberger's first and third criteria as well as QRS duration ≥124 ms were independent predictors of LVSD.</AbstractText>Bedside ECG parameters, such as the Goldberger criteria, may be useful in predicting LVSD before the use of more sophisticated diagnostic tests is considered in patients with suspected HF.</AbstractText> |
14,539 | Pulmonary embolism caused by delayed heparin-induced thrombocytopenia in a patient who received prophylactic LMWH. | Heparin induced thrombocytopenia (HIT) is a serious complication associated with heparin use. HIT usually develops between 5-14 days after starting heparin. Delayed-onset HIT can still occur 9-45 days after heparin had been discontinued. In patients with delayed HIT, the patient might be admitted to the hospital for new thrombosis and reexposure to heparin further worsens the patient's condition.</AbstractText>Our patient is a 71-year old female readmitted for worsening dyspnea 2 weeks after she was discharged from the hospital. On her previous hospitalization, she was diagnosed with bronchiolitis obliterans organizing pneumonia (BOOP). She had received prophylactic doses of LMWH. Dyspnea was initially thought to be secondary to CHF exacerbation secondary to atrial fibrillation with rapid ventricular response. She was started on a heparin. However, the patient's clinical condition deteriorated and she needed to be intubated. Her platelet counts also decreased rapidly. After CT angiography of the chest showed pulmonary embolism, HIT was strongly considered. All forms of heparin were discontinued and argatroban was started. However, the patient did not improve and she subsequently expired on the 7(th) hospital day. Heparin-induced antibodies came back positive that same day.</AbstractText>HIT is an immune-mediated disorder characterized by formation of antibodies against heparin-platelet factor 4 complex. The major clinical presentation of HIT is arterial and venous thrombosis. Once HIT is suspected, immediate cessation of any form of heparin is needed. Alternative anticoagulation must be started. Early treatment decreases the incidence of new thrombosis and stroke, and improves survival and cost savings.</AbstractText> |
14,540 | Fatal septicemia and endotoxic shock due to Aeromonas hydrophila. | Although rare, bloodstream infections caused by Aeromonas tend to be very severe and progress rapidly.</AbstractText>We report a case of an 81-year-old man with fetal septicemia and endotoxin shock caused by Aeromonas hydrophila. The patient had dilated cardiomyopathy, paroxysmal atrial fibrillation, interstitial pneumonitis and renal dysfunction was admitted to our hospital with chest pain and dyspnea. Transthoracic echocardiography demonstrated impaired left ventricular wall motion and severe mitral regurgitation due to tethering. Cardiac catheterization revealed severe stenotic lesions in the left anterior descending artery and the right coronary artery. Surgery for coronary artery bypass grafts and mitral annuloplasty were performed. However, 2 days after surgery, he suddenly developed a high-grade fever and his hemodynamics deteriorated rapidly. His blood cultures revealed gram-negative Bacillus and the endotoxin concentration in the blood was elevated. Despite intensive support efforts, the patient died 1 day after the sudden change. His blood culture revealed A. hydrophila.</AbstractText>Whenever Aeromonas is found in a patient's bloodstream, clinicians should start appropriate and intensive treatment immediately.</AbstractText> |
14,541 | Atrial Fibrillation with Rapid Ventricular Response following use of Dietary Supplement Containing 1,3 Dimethylamylamine and Caffeine. | Our nation?s servicemembers commonly use dietary supplements to enhance their performance. Despite this prolific use, many of these products have detrimental side-effects that compromise servicemembers? health and could, by proxy, compromise a mission. This paper presents the case of a 32-year old Navy Special Operations Forces (SOF) Sailor who, prior to physical training, used a supplement containing 1,3 Dimethylamylamine (DMAA), and then developed atrial fibrillation with rapid ventricular response. He required intravenous calcium channel blocker administration, followed by beta blockers, for rate control. As military providers, we routinely ask our patients about their use of supplements and while the regulation of these products is beyond the scope of practice for most of us, it is our duty to become better educated about the risks and benefits of these supplements. We must educate our patients and our commands on the potential harm that these supplements may pose. |
14,542 | [Microcirculatory parameters in patients with myocardial infarction]. | To estimate the prognostic value of the parameters of the microcirculatory bed for the assessment of risk for in-hospital death and cardiovascular events in patients with myocardial infarction (MI).</AbstractText>Thirty (62.5%) and 18 (37.5%) of 48 patients (mean age 63.5 +/- 10.2 years) admitted to an intensive care unit for acute coronary syndrome subsequently developed MI in the anterior and lower walls of the left ventricle (LV), respectively.</AbstractText>According to the GRACE scale, 28 (58.3%), 7 (14.6%), and 13 (18.1%) patients had high, low, and moderate risks for in-hospital death, respectively. Uncomplicated MI was noted in 18 (37.5%) of the patients; acute LV aneurysm was formed in 12 (25%); 14 (29.1%) had cardiac arrhythmias as frequent ventricular and supraventricular premature beats, paroxysms of ventricular fibrillation, ventricular tachycardia, atrial fibrillation and flutter. Early post-infarction angina pectoris was noted in 2 (4.2%) patients, Killip Class I and II heart failure in 36 (75%) and 12 (25%), respectively; 3 patients died (2 from myocardial rupture and 1 from ventricular fibrillation). According to GRACE scores, complicated MI was significantly more frequently encountered in patients at high risk for in-hospital death (75% versus 28.5% in those at low risk; p = 0.03). Analysis of the microcirculatory bed revealed substantial changes in microcirculation (MC), which reflected its hypereremic type and characterized high perfusion and high MC flow index. Moreover, the coefficient of variation (CV) was significantly higher than that in the control; on days 4 and 20 it did not virtually differ from that in the control on day 2.</AbstractText>The found changes in MC parameters (MC value and CV) may suggest the higher influence of active mechanisms for regulation of vascular tone as a response to myocardial necrosis. The role of the autonomic nervous system in the regulation of vascular tone is supported by the significant change in the normalized amplitudes of low- and high-frequency oscillations while the intravascular resistance index remained considerably higher at all follow-up stages, which may suggest that central hemodynamics is unstable in patients with MI and necessitates monitoring of their clinical status.</AbstractText> |
14,543 | Importance and inter-relationship of tissue Doppler variables for predicting adverse outcomes in high-risk patients: an analysis of 388 diabetic patients referred for coronary angiography. | To investigate the relative importance of individual tissue Doppler imaging variables to predict adverse events in a high-risk population with diabetes, ischaemic heart disease, and/or systolic dysfunction.</AbstractText>Transthoracic echocardiograms were analysed in 388 diabetic patients without significant valve disease, bundle branch block, and atrial fibrillation who underwent coronary angiography. Multivariable Cox's regression analyses were used to establish the association between peak systolic (s'), early diastolic (e'), and late diastolic (a') tissue velocities and outcomes (hospitalization for heart failure or death). The mean age and left ventricular ejection fraction (LVEF) was 66±10 years and 45±12%, respectively. During 2.3 (±1.0) years of follow-up, 91 patients (24%) met the combined endpoint. After adjustment for LVEF, coronary artery pathology, heart failure at baseline, age, and gender, each 1 cm/s decrease in s', e', and a' was associated with a hazard ratio (HR) of 1.18 (0.89-1.57), 1.03 (0.86-1.22), and 1.20 (1.05-1.37), respectively. A significant interaction was found between s' and a', P<0.01. In patients with lower than mean s', 1 cm/s decrease in a' was associated with HR 1.31 (1.10-1.55, P<0.01), whereas a' was without prognostic importance in patients with higher than mean s' [HR 0.99 (0.78-1.25, P=0.6)]. Patients having lower than mean values of both s' and a' had a poorer prognosis than patients having at least one of s' and a' high.</AbstractText>Peak systolic and late diastolic tissue velocities add prognostic information beyond LVEF in high-risk patients. Variables should be considered together as they interact on prognosis.</AbstractText> |
14,544 | Amiodarone-induced T-U fusion. | Amiodarone is a widely used antiarrythmic drug for various atrial and ventricular arrhythmias. It has the potential to cause prolongation of the QT interval, which, in turn, can increases the incidence of torsade de pointes. Amiodarone is also one of the causes of prominent U waves. The presented case exemplifies the phenomenon of amiodarone-induced T-U fusion and QT prolongation. Other causes of QT prolongation as electrolyte abnormalities or administration of other drugs that prolong the QT interval were excluded. Awareness of this phenomenon and method of calculation of QT interval in this scenario is of utmost importance. |
14,545 | Cerebrospinal fluid biochemistry reflects effects of therapeutic hypothermia after cardiac arrest in a porcine model. | Mild induced hypothermia (MIH) is recommended to treat neurologic injury after cardiac arrest (CA). However, clinical trials to assess MIH benefit after CA have been largely inconclusive. We investigated the subsequent changes in cerebrospinal fluid (CSF) biochemistry after MIH (33°C-34°C for 12 hours) and evaluated the importance of ongoing fever control.</AbstractText>Thirty-two male Wuzhishan inbred mini pigs (n = 16/group) underwent ventricular fibrillation followed by cardiopulmonary resuscitation and were randomized into 2 groups: hypothermic and control. Upon resumption of spontaneous circulation (ROSC) from CA, the hypothermic group was treated with MIH by endovascular cooling. The control group received no temperature intervention. Core temperatures were continually monitored. At various points throughout the procedure, CSF samples were obtained to measure glutamate, lactate, and pyruvate levels.</AbstractText>The core temperature of the hypothermic group was found to have increased postrewarming and reached levels comparable with those of the control group at ROSC 72 hours. In both groups, glutamate increased significantly after ROSC, but the glutamate levels in the hypothermic group were lower than those in the control group, except at ROSC 1 hour. The lactate-pyruvate ratio increased in the control group at ROSC 1 hour and was significantly lower in the hypothermic group (P < .05).</AbstractText>Mild induced hypothermia mitigated and delayed the CA-induced increase of CSF glutamate. Therefore, our results suggest that clinically inducing hypothermia as soon as possible after CA, or prolonging the time of MIH in combination with controlling ongoing fever, may enhance hypothermic protective effects.</AbstractText>Copyright © 2012 Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,546 | Continuous chest compressions improve survival and neurologic outcome in a swine model of prolonged ventricular fibrillation. | Evidence suggests that any interruptions, including those of rescue breaths, during cardiopulmonary resuscitation (CPR) have significant, detrimental effects on survival. The 2010 International Liaison Committee on Resuscitation guidelines strongly emphasized on the importance of minimizing interruptions during chest compressions. However, those guidelines also stress the need for ventilations in the case of prolonged cardiac arrest (CA), and it is not at present clear at which point of CA the necessity of providing ventilations overcomes the hemodynamic compromise caused by chest compressions' interruption.</AbstractText>Ventricular fibrillation was electrically induced in 20 piglets (19 ± 2 kg) and left untreated for 8 minutes. Animals were randomized to receive 2 minutes of either chest compression-only CPR (group CC) or standard 30:2 compressions/ventilations CPR (group S) before defibrillation. Resuscitated animals were monitored under anesthesia for 4 hours and then were awakened and placed in a maintenance facility for 24 hours.</AbstractText>There was no significant difference among groups for both return of spontaneous circulation and 1-hour survival. There was a significant difference in 24-hour survival (group CC, 7/10 vs group S, 2/10; P = .025). Blood lactate levels were significantly lower in group CC compared with group S in both 1 (P = .019) and 4 hours (P = .034) after return of spontaneous circulation. Furthermore, group CC animals exhibited significantly higher mean Neurologic Alertness Score (58 ± 42.4 vs 8 ± 16.9) (P < .05).</AbstractText>In this swine CA model, where defibrillation was first attempted at 10 minutes of untreated ventricular fibrillation, uninterrupted chest compressions resulted in significantly higher survival rates and higher 24-hour neurologic scores, compared with standard 30:2 CPR.</AbstractText>Copyright © 2012 Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,547 | Novel association patterns of cardiac remodeling markers in patients with essential hypertension and atrial fibrillation. | Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are essential for the cardiac extracellular matrix (ECM) remodeling. We investigated differences in serum levels of these markers between patients with atrial fibrillation (AF) and sinus rhythm (SR).</AbstractText>Serum levels of MMP-2, MMP-3, MMP-9 and TIMP-1 were measured in 86 patients: 27 on SR without any AF history, 33 with paroxysmal and 26 with permanent AF. All subjects had essential hypertension, normal systolic function and no coronary artery disease.</AbstractText>Patients with AF had higher MMP-2, MMP-3 and MMP-9 and lower TIMP-1 compared to SR subjects (all p < 0.001). Paroxysmal AF was associated with higher MMP-2 levels compared to permanent AF (p < 0.001). Matrix metalloproteinase-9 but not MMP-3 was higher in permanent compared to paroxysmal AF group (p < 0.001). Patients with AF had lower levels of TIMP-1 compared to those with SR while permanent AF subjects had lower TIMP-1 levels than those with paroxysmal AF (p < 0.001 for both comparisons). Lower TIMP-1 was the only independent factor associated with AF (OR: 0.259, 95%CI: 0.104-0.645, p = 0.004).</AbstractText>In hypertensives, paroxysmal AF and permanent AF differ with respect to serum MMPs. Increased MMP-2 is associated with paroxysmal, whereas increased MMP-9 with permanent AF. Additionally, lower levels of TIMP-1 had a strong association with AF incidence.</AbstractText> |
14,548 | What is the role of chest compression depth during out-of-hospital cardiac arrest resuscitation? | The 2010 international guidelines for cardiopulmonary resuscitation recently recommended an increase in the minimum compression depth from 38 to 50 mm, although there are limited human data to support this. We sought to study patterns of cardiopulmonary resuscitation compression depth and their associations with patient outcomes in out-of-hospital cardiac arrest cases treated by the 2005 guideline standards.</AbstractText>Prospective cohort.</AbstractText>Seven U.S. and Canadian urban regions.</AbstractText>We studied emergency medical services treated out-of-hospital cardiac arrest patients from the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest for whom electronic cardiopulmonary resuscitation compression depth data were available, from May 2006 to June 2009.</AbstractText>We calculated anterior chest wall depression in millimeters and the period of active cardiopulmonary resuscitation (chest compression fraction) for each minute of cardiopulmonary resuscitation. We controlled for covariates including compression rate and calculated adjusted odds ratios for any return of spontaneous circulation, 1-day survival, and hospital discharge.</AbstractText>We included 1029 adult patients from seven U.S. and Canadian cities with the following characteristics: Mean age 68 yrs; male 62%; bystander witnessed 40%; bystander cardiopulmonary resuscitation 37%; initial rhythms: Ventricular fibrillation/ventricular tachycardia 24%, pulseless electrical activity 16%, asystole 48%, other nonshockable 12%; outcomes: Return of spontaneous circulation 26%, 1-day survival 18%, discharge 5%. For all patients, median compression rate was 106 per minute, median compression fraction 0.65, and median compression depth 37.3 mm with 52.8% of cases having depth <38 mm and 91.6% having depth <50 mm. We found an inverse association between depth and compression rate ( p < .001). Adjusted odds ratios for all depth measures (mean values, categories, and range) showed strong trends toward better outcomes with increased depth for all three survival measures.</AbstractText>We found suboptimal compression depth in half of patients by 2005 guideline standards and almost all by 2010 standards as well as an inverse association between compression depth and rate. We found a strong association between survival outcomes and increased compression depth but no clear evidence to support or refute the 2010 recommendations of >50 mm. Although compression depth is an important component of cardiopulmonary resuscitation and should be measured routinely, the most effective depth is currently unknown.</AbstractText> |
14,549 | Treating cardiac arrhythmias detected with an implantable cardiac monitor in patients after an acute myocardial infarction. | Using an implantable cardiac monitor (ICM) in patients with acute myocardial infarction (MI) allows continuous electrocardiogram monitoring and provides a much more detailed picture of the incidence of brady- and tachyarrhythmias than conventional follow-up. The CARISMA study was the first to use the ICM in post-MI patients with moderate to severe left ventricular systolic dysfunction. Atrial fibrillation (AF) events lasting longer than 30 s were associated with an almost threefold increase in the risk of major cardiac events. This confirms the current definition of clinically significant AF episodes, as patients with episodes of shorter duration were not at increased risk. The association of AF to progressive heart failure, reinfarction, and cardiovascular death underlines the need for an intensive follow-up of post-MI patients with new-onset AF in order to reveal underlying causes of AF such as progressive left ventricular dysfunction or myocardial ischemia. Asymptomatic, especially nightly, bradycardia episodes including high-degree 2°-3° atrioventricular (AV) block, sinus bradycardia, and sinus arrest were frequently documented by ICM in the CARISMA study. Ten percent of patients experienced high-degree 2°-3° AV block, of which the main part was nightly and asymptomatic, and 50% of all cardiovascular deaths occurred in this group, most from severe heart failure. Therefore, in post-MI patients with paroxysmal high-degree AV block, pacemaker implantation should be done, and in the case of left ventricular dysfunction (LVEF ≤ 35%), an implantable cardioverter defibrillator/cardiac resynchronization therapy defibrillator (ICD/CRT-D) may be indicated. Nonsustained ventricular tachycardia (VT) is very frequent in post-MI patients, and in the CARISMA study, high-risk patients with nonsustained VT were implanted with an ICD. Furthermore, in 10% of the patients, the ICM recorded nonsustained VT episodes of ≥ 16 beats per minute, resulting in a twofold increase in the risk for cardiac death. Thus, patients with nonsustained VT should undergo careful investigation, and we recommend a repeat echocardiography and electrophysiological stimulation in these patients. Patients with sustained VT or VF should receive an ICD. |
14,550 | Early mineralocorticoid receptor blockade in primary percutaneous coronary intervention for ST-elevation myocardial infarction is associated with a reduction of life-threatening ventricular arrhythmia. | Aldosterone levels are high early after admission for ST elevation myocardial infarction (STEMI) concomitantly with high risk of sudden death and life-threatening ventricular arrhythmia.</AbstractText>We assessed the hypothesis that early aldosterone blockade on admission for primary percutaneous coronary intervention (PCI) may be associated with a reduction of life-threatening ventricular arrhythmia in a prospective cohort-nested case (n=159) versus historical control (n=623) study. All cases were treated on admission by 200mg IV bolus of potassium canrenoate, followed by 25mg PO spironolactone daily during the coronary care unit stay. The primary endpoint--in-hospital composite of death, resuscitated cardiac arrest and ventricular tachycardia--was assessed by logistic regression models adjusted on major pre-specified variables and validated by a bootstrap procedure and propensity-score based analyses.</AbstractText>Aldosterone blockade was associated with lower risks of the primary endpoint (adjusted ORs 0.26, 95% CI [0.13-0.57]), resuscitated cardiac arrest (adjusted OR 0.39, 95% CI [0.16-0.94]), ventricular tachycardia or fibrillation (adjusted ORs 0.23, 95% CI [0.12-0.45]), as well as ventricular arrhythmia requiring resuscitation or anti-arrhythmic therapy (adjusted OR 0.41, 95% CI [0.19-0.88]). All findings were confirmed by the bootstrap procedure. The benefit on death or resuscitated cardiac arrest seemed sustained at 6month follow-up.</AbstractText>Early aldosterone blockade in patients presenting for primary PCI for STEMI is associated with significant reductions in rates of life-threatening arrhythmia and cardiac arrest independent of the initial risk profile, heart failure or hemodynamic status. These findings support the concept of aldosterone blockade early after STEMI, warranting further confirmation by ongoing randomized trials.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,551 | Heterogeneity of left ventricular signal characteristics in response to acute vagal stimulation during ventricular fibrillation in dogs. | Studies have shown that long-term vagal stimulation is protective against ventricular fibrillation; however, the effects of acute vagal stimulation during ventricular fibrillation in the normal heart have not been investigated. We examined the effects of acute vagal stimulation on ventricular fibrillation in a canine model. In 4 dogs, we induced 30-second periods of ventricular fibrillation by means of intraventricular pacing. During 2 of the 4 periods of fibrillation that we analyzed, vagal stimulation was delivered through electrodes in the caudal ends of the vagus nerves. Noncontact unipolar electrograms were recorded from 3 ventricular regions: the basal septum, apical septum, and lateral free wall. We then computed the most frequent cycle length, mean organization index, and mean electrogram amplitude for each region. During fibrillation, vagal stimulation shortened the most frequent cycle lengths in the basal septum (P=0.02) and apical septum (P=0.0001), but not in the lateral wall (P=0.46). In addition, vagal stimulation significantly reduced the mean organization indices in the apical septum (P <0.001) and lateral wall (P <0.001), but not in the basal septum (P=0.19). Furthermore, vagal stimulation raised the mean electrogram amplitude in the basal septum (P <0.01) but lowered it substantially in the apical septum (P=0.00005) and lateral wall (P=0.00003). We conclude that vagal stimulation acutely affects the characteristics of ventricular fibrillation in canine myocardium in a spatially heterogeneous manner. This nonuniformity of response may have implications with regard to manipulating the autonomic system as a means of modifying the substrate for ventricular dysrhythmias. |
14,552 | Spontaneous ventricular fibrillation in right ventricular failure secondary to chronic pulmonary hypertension. | Right ventricular failure (RVF) in pulmonary hypertension (PH) is associated with increased incidence of sudden death by a poorly explored mechanism. We test the hypothesis that PH promotes spontaneous ventricular fibrillation (VF) during a critical post-PH onset period characterized by a sudden increase in mortality.</AbstractText>Rats received either a single subcutaneous dose of monocrotaline (MCT, 60 mg/kg) to induce PH-associated RVF (PH, n=24) or saline (control, n=17). Activation pattern of the RV-epicardial surface was mapped using voltage-sensitive dye in isolated Langendorff-perfused hearts along with single glass-microelectrode and ECG-recordings. MCT-injected rats developed severe PH by day 21 and progressed to RVF by approximately day 30. Rats manifested increased mortality, and ≈30% rats died suddenly and precipitously during 23-32 days after MCT. This fatal period was associated with the initiation of spontaneous VF by a focal mechanism in the RV, which was subsequently maintained by both focal and incomplete reentrant wave fronts. Microelectrode recordings from the RV-epicardium at the onset of focal activity showed early afterdepolarization-mediated triggered activity that led to VF. The onset of the RV cellular triggered beats preceded left ventricular depolarizations by 23±8 ms. The RV but not the left ventricular cardiomyocytes isolated during this fatal period manifested significant action potential duration prolongation, dispersion, and an increased susceptibility to depolarization-induced repetitive activity. No spontaneous VF was observed in any of the control hearts. RVF was associated with significantly reduced RV ejection fraction (P<0.001), RV hypertrophy (P<0.001), and RV fibrosis (P<0.01). The hemodynamic function of the LV and its structure were preserved.</AbstractText>PH-induced RVF is associated with a distinct phase of increased mortality characterized by spontaneous VF arising from the RV by an early afterdepolarization-mediated triggered activity.</AbstractText> |
14,553 | Comparison of Microlife BP A200 Plus and Omron M6 blood pressure monitors to detect atrial fibrillation in hypertensive patients. | Self-monitoring home blood pressure (BP) devices are currently recommended for long-term follow-up of hypertension and its management. Some of these devices are integrated with algorithms aimed at detecting atrial fibrillation (AF), which is common essential hypertension. This study was designed to compare the diagnostic accuracy of two widely diffused home BP monitoring devices in detecting AF in an unselected population of outpatients referred to a hypertension clinic because of high BP.</AbstractText>In 503 consecutive patients the authors simultaneously compared the accuracy of the Microlife(®) BP A200 Plus (Microlife) and the OMRON(®) M6 (OMRON) home BP devices, in detecting AF.</AbstractText>Systolic and diastolic BP as well as heart rate (HR) values detected by the two devices were not significantly different. Pulse irregularity was detected in 124 and 112 patients with the OMRON M6 and Microlife BP A200 Plus devices, respectively. Simultaneous electrocardiogram (ECG) recording revealed that pulse irregularity was due to AF in 101 patients. Pulse irregularity detected by the OMRON M6 device corresponded to AF in 101, to supraventricular premature beats in 18, and to frequent premature ventricular beat in five patients, respectively. Pulse irregularity detected by the Microlife BP A200 Plus device corresponded to AF in 93, to supraventricular premature beats in 14, and to ventricular premature beats in five patients. The sensitivity for detecting AF was 100%, the specificity was 92%, and diagnostic accuracy 95% for the OMRON M6 and 100%, 92%, and 95 for the Microlife BP A200 Plus, respectively. AF was newly diagnosed by ECG recordings in 47 patients, and was detected in all patients by the OMRON device, and in 42 patients by the Microlife device.</AbstractText>These results indicate that OMRON M6 is more accurate than Microlife BP A200 Plus in detecting AF in patients with essential hypertension. Widespread use of these devices in hypertensive patients could be of clinical benefit for the early diagnosis and treatment of this arrhythmia and related consequences.</AbstractText> |
14,554 | Comparison of defibrillation efficacy between two pads placements in a pediatric porcine model of cardiac arrest. | The placement of defibrillation pads at ideal anatomical sites is one of the major determinants of transthoracic defibrillation success. However, the optimal pads position for ventricular defibrillation is still undetermined. In the present study, we compared the effects of two different pads positions on defibrillation success rate in a pediatric porcine model of cardiac arrest.</AbstractText>Eight domestic male pigs weighing 12-15 kg were randomized to receive shocks using either the anterior-posterior (AP) or the anterior-lateral (AL) position with pediatric pads. Ventricular fibrillation (VF) was electrically induced and untreated for 30 s. A sequence of randomized biphasic electrical shocks ranging from 10 to 100 J was attempted. If the defibrillation failed to terminate VF, a 100 J rescuer shock was then delivered. After a recovery interval of 5 min, the sequence was repeated for a total of approximately 30 test shocks were attempted for each animal. The dose response curves were constructed and the defibrillation thresholds were compared between groups.</AbstractText>The aggregated success rate was 65.6% for AP placement and 43.0% for AL one (p=0.0005) when shock energy was between 10 and 70 J. A significantly lower 50% defibrillation threshold was obtained for AP pads placement compared with traditional AL pads position (2.1±0.4 J/kg vs. 3.6±0.9 J/kg, p=0.041).</AbstractText>In this pediatric porcine model of cardiac arrest, the anterior-posterior placement of pediatric pads yielded a higher success rate by lowering defibrillation threshold compared to the anterior-lateral position.</AbstractText>Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,555 | Characteristics and outcomes of peripartum versus nonperipartum cardiomyopathy in women using a wearable cardiac defibrillator. | Peripartum cardiomyopathy (PPCM) mortality rates vary between 2% and 56%, with half occurring ≤12 weeks'; postpartum. Although risk factors for PPCM have been identified, predicting sudden cardiac death among PPCM patients remains difficult. This study describes the characteristics and outcomes of PPCM patients and controls referred for a wearable cardioverter defibrillator (WCD).</AbstractText>Deidentified WCD medical orders between 2003 and 2009 and death index searches were used to characterize women (ages 17-43) with PPCM (n = 107) or matched nonpregnant women with nonischemic dilated cardiomyopathy (NIDCM; n = 159). Demographics were similar. WCD use averaged 124 ± 123 days and 96 ± 83 days among PPCM and NIDCM patients, respectively. No PPCM patients received an appropriate shock for ventricular tachycardia/ventricular fibrillation; 1 NIDCM patient received 2 successful shocks. No PPCM patient died during WCD use versus 11 concurrent NIDCM deaths. After WCD use, 3 PPCM and 13 NIDCM patients died, respectively.</AbstractText>The mortality rate of 2.8% (over 3.0 ± 1.2 years) in PPCM patients is low compared to published data. The role of WCD therapy among PPCM patients deserves further study.</AbstractText>Copyright © 2012 Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,556 | Prognostic significance of postprocedural sustained ventricular tachycardia or fibrillation in patients undergoing primary percutaneous coronary intervention (from the HORIZONS-AMI Trial). | The prognostic significance of postprocedure sustained ventricular tachycardia or ventricular fibrillation (VT/VF) in patients undergoing primary percutaneous coronary intervention (PPCI) for ST-segment elevation myocardial infarction (STEMI) has rarely been studied, although a previous study has suggested that its occurrence portends decreased survival. We examined outcomes from the prospective large-scale multicenter randomized HORIZONS-AMI trial to evaluate the incidence, clinical correlates, and outcomes of in-hospital sustained VT/VF after PPCI. Of 3,485 patients undergoing PPCI in whom VT/VF did not occur before or during the procedure, 181 patients (5.2%) developed VT/VF after PPCI. Most postprocedural VT/VF episodes (85%) occurred in the first 48 hours. Patients with postprocedural VT/VF were more likely men with Killip class > I on presentation but had a lower prevalence of hypertension and diabetes. Patients with postprocedural VT/VF were also less frequently taking β blockers and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers at admission. Mean door-to-balloon time was shorter and Thrombolysis In Myocardial Infarction grade 0 flow before PPCI was more common in patients with VT/VF, although Thrombolysis In Myocardial Infarction grade 3 flow rates after PPCI did not vary. There were no significant differences in adjusted 3-year rates of mortality (hazard ratio 0.73, 95% confidence interval 0.30 to 1.79) or composite major adverse clinical events (death, myocardial infarction, target vessel revascularization, or stroke; hazard ratio 0.71, 95% confidence interval 0.44 to 1.15) in patients with versus without postprocedural sustained VT/VF. In conclusion, sustained VT/VF after PPCI in the HORIZONS-AMI trial was not significantly associated with 3-year mortality or major adverse clinical events. Further studies are required to address the prognostic significance of VT/VF in patients with STEMI undergoing PPCI. |
14,557 | Outcomes of patients treated with triple antithrombotic therapy after primary percutaneous coronary intervention for ST-elevation myocardial infarction (from the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction [HORIZONS-AMI] trial). | In the setting of ST-segment elevation myocardial infarction (STEMI), patients at high risk of systemic emboli who undergo primary percutaneous coronary intervention (PCI) using stents might require triple antithrombotic therapy (a combination of aspirin, thienopyridine, and vitamin K antagonist [VKA]). The risks and benefits of such therapy in the setting of STEMI have been incompletely characterized. We, therefore, assessed the outcomes of patients who received triple therapy after primary PCI in the large-scale, contemporary Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction [HORIZONS-AMI] trial. Among the 3,320 patients triaged to primary PCI, 126 (3.8%) were prescribed triple therapy and 3,194 (96.2%) were prescribed dual antiplatelet therapy. The most frequent indications for VKA treatment were a severely reduced left ventricular ejection fraction with a large akinetic area, atrial fibrillation (23.8% each), and mural thrombus (23.0%). The assignment to triple therapy was associated with older age, female gender, rhythm disturbances, Killip class > 1 on admission, lower left ventricular ejection fraction, left anterior descending artery territory infarcts, and Final Thrombolysis In Myocardial Infarction flow grade < 3. Patients treated with triple versus dual therapy had comparable short- and long-term ischemic outcomes but had significantly increased rates of major bleeding during the index hospitalization (17.1% vs 6.5%, p < 0.0001), resulting in premature VKA discontinuation in 14.3% of those patients. In conclusion, in the setting of STEMI treated with primary PCI, the combination of aspirin, thienopyridine, and VKA results in an excess of bleeding complications and premature discontinuation of VKA. The risk of adding oral anticoagulation to patients admitted for STEMI should be carefully considered before choosing drug-eluting or bare metal stents. |
14,558 | Early cardiac arrest in patients hospitalized with pneumonia: a report from the American Heart Association's Get With The Guidelines-Resuscitation Program. | Pneumonia is the leading infectious cause of death. Early deterioration and death commonly result from progressive sepsis, shock, respiratory failure, and cardiac complications. Recent data suggest that cardiac arrest may also be common, yet few previous studies have addressed this. Accordingly, we sought to characterize early cardiac arrest in patients who are hospitalized with coexisting pneumonia.</AbstractText>We performed a retrospective analysis of a multicenter cardiac arrest database, with data from > 500 North American hospitals. We included in-hospital cardiac arrest events that occurred in community-dwelling adults with pneumonia within the first 72 h after hospital admission. We compared patient and event characteristics for patients with and without pneumonia. For patients with pneumonia, we also compared events according to event location.</AbstractText>We identified 4,453 episodes of early cardiac arrest in patients who were hospitalized with pneumonia. Among patients with preexisting pneumonia, only 36.5% were receiving mechanical ventilation and only 33.3% were receiving infusions of vasoactive drugs prior to cardiac arrest. Only 52.3% of patients on the ward were receiving ECG monitoring prior to cardiac arrest. Shockable rhythms were uncommon in all patients with pneumonia (ventricular tachycardia or fibrillation, 14.8%). Patients on the ward were significantly older than patients in the ICU.</AbstractText>In patients with preexisting pneumonia, cardiac arrest may occur in the absence of preceding shock or respiratory failure. Physicians should be alert to the possibility of abrupt cardiopulmonary collapse, and future studies should address this possibility. The mechanism may involve myocardial ischemia, a maladaptive response to hypoxia, sepsis-related cardiomyopathy, or other phenomena.</AbstractText> |
14,559 | Medical treatment of atrial fibrillation. | Atrial fibrillation is an increasingly common arrhythmia which is associated with a substantial burden of cardiovascular disease. The arrhythmia is mostly treated with pharmacological therapy, although some interventional techniques such as left atrial ablation, atrioventricular nodal ablation plus pacemaker implantation, and left atrial appendage occlusion or excision are gaining popularity. The concept of primary prevention of atrial fibrillation with therapies targeting the formation and progression of atrial substrate has also recently evolved. Medical treatment is directed at either rate control (slowing the ventricular rate and allowing atrial fibrillation to continue) or rhythm control (restoring and maintaining sinus rhythm). There are different types of therapy for each purpose. Antiarrhythmic drug therapy, however, is difficult and inadequate with the agents that are now available. Treatment may be ineffective or complicated by cardiac or extracardiac adverse effects. Guidelines exist to help physicians choose appropriate therapies, but they have required and continue to need revision to cope with the rapid development and accumulating experience with new treatments. This review provides a contemporary evidence-based insight into the medical management of atrial fibrillation in the modern era. |
14,560 | A common β1-adrenergic receptor polymorphism predicts favorable response to rate-control therapy in atrial fibrillation. | In this study, we evaluated the impact of 2 common β1-adrenergic receptor (β1-AR) polymorphisms (G389R and S49G) in response to ventricular rate control therapy in patients with atrial fibrillation (AF).</AbstractText>Randomized studies have shown that ventricular rate control is an acceptable treatment strategy in patients with AF. However, identification of patients who will adequately respond to rate-control therapy remains a challenge.</AbstractText>We studied 543 subjects (63% men; age 61.8 ± 14 years) prospectively enrolled in the Vanderbilt AF registry and managed with rate-control strategy. A "responder" displayed adequate ventricular rate control based on the AFFIRM (Atrial Fibrillation Follow-Up Investigation of Rhythm Management) criteria: average heart rate (HR) at rest ≤80 beats/min; and maximum HR during a 6-min walk test ≤110 beats/min or average HR during 24-h Holter ≤100 beats/min.</AbstractText>A total of 295 (54.3%) patients met the AFFIRM criteria. Baseline clinical characteristics were similar in responders and nonresponders except for mean resting HR (76 ± 20 beats/min vs. 70 ± 15 beats/min; p < 0.01) and smoking (6% vs. 1%; p < 0.01). Multiple clinical variables (age, gender, hypertension) failed to predict response to rate-control therapy. By contrast, carriers of Gly variant at 389 were more likely to respond favorably to rate-control therapy; 60% versus 51% in the Arg389Arg genotype, p = 0.04. This association persisted after correction for multiple clinical factors (odds ratio: 1.42, 95% confidence interval: 1.00 to 2.03, p < 0.05). Among responders, subjects carrying the Gly389 variant required the lowest doses of rate-control medications; atenolol: 92 mg versus 68 mg; carvedilol: 44 mg versus 20 mg; metoprolol: 80 mg versus 72 mg; diltiazem: 212 mg versus 180 mg, and verapamil: 276 mg versus 200 mg, respectively (p < 0.01 for all comparisons).</AbstractText>We have identified a common β1-AR polymorphism, G389R, that is associated with adequate response to rate-control therapy in AF patients. Gly389 is a loss-of-function variant; consequently, for the same adrenergic stimulation, it produces reduced levels of adenyl cyclase, and hence, attenuates the β-adrenergic cascade. Mechanistically, the effect of rate-control drugs will be synergistic with that of the Gly389 variant, which could possibly explain our findings. These findings represent a step forward in the development of a long-term strategy of selecting treatment options in AF based on genotype.</AbstractText>Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,561 | Risk stratification in Brugada syndrome: results of the PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) registry. | The PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) prospective registry was designed to assess the predictive accuracy of sustained ventricular tachycardia/ventricular fibrillation (VTs/VF) inducibility and to identify additional predictors of arrhythmic events in Brugada syndrome patients without history of VT/VF.</AbstractText>Brugada syndrome is a genetic disease associated with increased risk of sudden cardiac death. Even though its value has been questioned, inducibility of VTs/VF is widely used to select candidates to receive a prophylactic implantable defibrillator, and its accuracy has never been addressed in prospective studies with homogeneous enrolling criteria.</AbstractText>Patients with a spontaneous or drug-induced type I electrocardiogram (ECG) and without history of cardiac arrest were enrolled. The registry included 308 consecutive individuals (247 men, 80%; median age 44 years, range 18 to 72 years). Programmed electrical stimulation was performed at enrollment, and patients were followed-up every 6 months.</AbstractText>During a median follow-up of 34 months, 14 arrhythmic events (4.5%) occurred (13 appropriate shocks of the implantable defibrillator, and 1 cardiac arrest). Programmed electrical stimulation performed with a uniform and pre-specified protocol induced ventricular tachyarrhythmias in 40% of patients: arrhythmia inducibility was not a predictor of events at follow-up (9 of 14 events occurred in noninducible patients). History of syncope and spontaneous type I ECG (hazard ratio [HR]: 4.20), ventricular refractory period <200 ms (HR: 3.91), and QRS fragmentation (HR: 4.94) were significant predictors of arrhythmias.</AbstractText>Our data show that VT/VF inducibility is unable to identify high-risk patients, whereas the presence of a spontaneous type I ECG, history of syncope, ventricular effective refractory period <200 ms, and QRS fragmentation seem useful to identify candidates for prophylactic implantable cardioverter defibrillator.</AbstractText>Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,562 | Changes in renal function after implantation of continuous-flow left ventricular assist devices. | The aim of this study was to determine renal outcomes after left ventricular assist device (LVAD) implantation.</AbstractText>Renal dysfunction before LVAD placement is frequent, and it is unclear whether it is due to primary renal disease or to poor perfusion.</AbstractText>A retrospective single-center analysis was conducted in 83 consecutive patients implanted with HeartMate II continuous-flow LVADs (Thoratec Corp., Pleasanton, California). Calculated glomerular filtration rate (GFR) was assessed on admission and 1, 3, and 6 months after implantation. To define predictors for improvement in GFR, clinical variables were examined in patients with decreased renal function (GFR <60 ml/min/1.73 m(2)) before LVAD, surviving and dialysis-free at 1 month (n = 44).</AbstractText>GFR significantly increased from admission (53.2 ± 21.4 ml/min/1.73 m(2)) to 1 month after LVAD implantation (87.4 ± 27.9 ml/min/1.73 m(2)) (p < 0.0001). Subsequently, at 3 and 6 months, GFR remained significantly (p < 0.0001) above pre-LVAD values. Of the 51 patients with GFRs <60 ml/min/1.73 m(2) before LVAD surviving at 1 month, 34 (67%) improved to GFRs >60 ml/min/1.73 m(2). Univariate pre-operative predictors for improvement in renal function at 1 month included younger age (p = 0.049), GFR improvement with optimal medical therapy (p < 0.001), intra-aortic balloon pump use (p = 0.004), kidney length above 10 cm (p = 0.023), no treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (p = 0.029), higher bilirubin (p = 0.002), higher Lietz-Miller score (p = 0.019), and atrial fibrillation (p = 0.007). Multivariate analysis indicated pre-operative improved GFR (slope = 0.5 U per unit improved; 95% confidence interval: 0.2 to 0.8; p = 0.003), atrial fibrillation (slope = 27; 95% confidence interval: 8 to 46; p = 0.006), and intra-aortic balloon pump use (slope = 14; 95% confidence interval: 2 to 26; p = 0.02) as independent predictors.</AbstractText>In most patients with end-stage heart failure considered for LVAD implantation, renal dysfunction is reversible and likely related to poor renal perfusion.</AbstractText>Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
14,563 | [Effects of metoprolol on electrophysiology of ischemic and anoxic myocardium in diabetic rats]. | To investigate the effects of metoprolol on electrophysiology of ischemic and anoxic myocardium in diabetic rats.</AbstractText>Forty Sprague-Dawley (SD) rats were divided into 4 groups: diabetes group; diabetes and ablation of left sympathetic nerve group; diabetes and metoprolol group and sham group. The diabetes model was induced by intraperitoneal injection of streptozotocin (STZ, 60 mg/kg). The ventricular diastolic effective threshold (DET), effective refractive period (ERP), and Ventricular fibrillation threshold (VFT) were measured. The serum concentration of nerve growth factor (NGF) was measured.</AbstractText>Metoprolol increased DET of ischemic and anoxic myocardium in diabetic rats. The ablation of the left sympathetic nerve increased VFT of diabetic rats. VFT in metoprolo group was significantly increased compared to diabetes group after ischemia. The concentrations of NGF in diabetic group and metoprolol group were higher than those in sham group. There were no difference in NGF levels between ablation of left sympathetic nerve group and sham group.</AbstractText>The remodeling of sympathetic nerve affects the electrophysiology of ischemic myocardium of diabetic rats. Metoprolol can increase the VFT and decrease the excitation threshold of the ischemic myocardium in diabetic rats.</AbstractText> |
14,564 | Successful surgical repair of a giant calcified left ventricular aneurysm: a report of a case. | A 68-year-old man presented at the outpatient clinic with epigastric discomfort. He had suffered a myocardial infarction 10 years previously. Chest radiography and computed tomography showed a giant calcified aneurysm in the left ventricle. Electrocardiography indicated atrial fibrillation. Echocardiography showed moderate mitral regurgitation and enlarged left atrium. End-diastolic volume and ejection fraction were 164 ml and 31%, respectively. Coronary angiography revealed total occlusion of the left anterior descending artery and diffuse stenosis of the right coronary artery. Aneurysmectomy, mitral annuloplasty, maze procedure, and coronary artery bypass were performed. The patient was discharged 16 days postoperatively in a satisfactory condition without complications. |
14,565 | [Intermittent short QT interval in a patient with sudden cardiac death]. | This paper presents a 21 years-old-male without structural heart disease who was reanimated from a sudden cardiac death event. His familial history included two siblings suddenly dead in their first year of life. The patient had 10 episodes of ventricular tachycardia (some of them were registered). Electrocardiographically abnormalities were an intermittent short QT interval (280 ms), short QTc (320 ms) and a short ST segment. QT interval subsequently returned to a normal range (360 ms or more), while occasionally a length of 335 ms was recorded. The electrophysiological study findings (AH and HV intervals, refractory periods) were normal. The patient refused the implantable cardioverter defibrillator and he is receiving oral amiodarone (200 mg/day). The evolution has been satisfactory along four years. Sequential electrocardiograms are very important to identify patients with an intermittent short QT interval. Shortening of the interval J wave-Tpeak is also relevant. Related arrhythmias could be ventricular tachycardia or fibrillation. |
14,566 | Visual three-dimensional representation of beat-to-beat electrocardiogram traces during hemodiafiltration. | This study evaluated the usefulness of the three-dimensional representation of electrocardiogram traces (3DECG) to reveal acute and gradual changes during a full session of hemodiafiltration (HDF) in end-stage renal disease (ESRD) patients. Fifteen ESRD patients were included (six men, nine women, age 46 ± 19 years old). Serum electrolytes, blood pressure, heart rate, and blood urea nitrogen (BUN) were measured before and after HDF. Continuous electrocardiograms (ECGs) obtained by Holter monitoring during HDF were used to produce the 3DECG. Several major disturbances were identified by 3DECG images: increase in QRS amplitude (47%), decrease in T-wave amplitude (33%), increase in heart rate (33%), and occurrence of arrhythmia (53%). Different arrhythmia types were often concurrent and included isolated supraventricular premature beats (N = 5), atrial fibrillation or atrial bigeminy (N = 2), and isolated premature ventricular beats (N = 6). Patients with decrease in T-wave amplitude had higher potassium and BUN (both before HDF and total removal) than those without decrease in T-wave amplitude (P < 0.05). Concurrent acute and gradual ECG changes during HDF are identified by the 3DECG, which could be useful as a preventive and prognostic method. |
14,567 | Analysis of left ventricular impedance in comparison with ultrasound images. | Cardiac monitoring of ventricular assist devices (VADs) is important for detecting heart failure risks, such as critical arrhythmia and ventricular fibrillation, and for supplying data that are useful for hemodynamic control. Specifically, impedance cardiograms (ICGs) are especially beneficial because they have no effect on the tissue or organs and can monitor various parameters simultaneously, including the heart rate and heart contractions. In this article, we measured impedance changes in porcine left ventricles using electrodes placed around the inlet and outlet cannulae of the VAD. The measured left ventricular impedance (LVI) waveform changes are caused by heart movements, such as cardiac muscle contraction and changes in blood volume as a result of heart filling and emptying. In contrast to other impedance measurements, LVI is less affected by the movement of other organs. Using a porcine model, LVIs were measured and compared with blood flow data measured with an ultrasound blood flowmeter. The ICG showed the same frequency as the animal's heart rate, and their amplitudes were closely related to cardiac output (CO). However, the waveform differed from other vital signs, such as CO, electrocardiogram, and blood pressure. Ultrasound images were used to explain the impedance waveform. In the ultrasound images, we obtained the shape and size of the animal's heart and calculated the predicted impedance data. We then compared these to the actual measured data. These results show that the impedance signal contains detailed information on heart rate and CO; these results were unaffected by the cannulae or VAD perfusion. |
14,568 | Fatal undersensing of ventricular fibrillation due to intermittent high-amplitude R waves. | A 48-year-old man was admitted after an episode of aborted sudden death with external defibrillation. An implantable cardioverter defibrillator implanted 2 years before for secondary prevention failed to sense properly an episode of ventricular fibrillation. Interrogation of the device showed large oscillatory changes of the amplitude of the local electrogram during ventricular fibrillation, causing undersensing and inappropriate refraining from shock therapy. |
14,569 | [Mitral valve replacement for heart failure due to hypertrophic obstructive cardiomyopathy; report of a case]. | Myotomy or myectomy are well known as the standard treatment of hypertrophic obstructive cardiomyopathy (HOCM), and mitral valve replacement (MVR) is reported to achieve the equivalent therapeutic effect. And recently, combined treatment with artificial chordae replacement and MVR has been reported to improve the prognosis. We herein describe a case of a patient with HOCM who developed acute exacerbation of heart failure. The patient was 74-year-old woman, who had been followed by chronic atrial fibrillation (Af) and HOCM for 3 years. The findings at echocardiography included septal hypertrophy, systolic anterior motion (SAM) of the mitral valve, severe stenosis of left ventricular outflow tract (LVOT), and severe mitral valve regurgitation (MR). Calcification of mitral valve was also found. After the medical management, the patient was treated successfully by MVR using a mechanical valve combined with artificial chordae replacement. Maze procedure was also performed for chronic Af. The postoperative course was uneventful. MVR combined with artificial chordae replacement could be one of the useful strategies for HOCM associated with severe MR and organic changes of mitral valve. |
14,570 | Myocardial perfusion abnormality in the area of ventricular septum-free wall junction and cardiovascular events in nonobstructive hypertrophic cardiomyopathy. | Myocardial perfusion abnormality in the left ventricle is known to be prognostic in patients with hypertrophic cardiomyopathy (HCM). Magnetic resonance imaging and necropsy studies on HCM hearts revealed myocardial lesions predominating in the area of ventricular septum-free wall junction. We assessed perfusion abnormality in this area and correlated it with the prognosis of HCM patients. We performed exercise Tc-99m tetrofosmin myocardial scintigraphy in 55 patients with nonobstructive HCM. Perfusion abnormalities were semiquantified using a 5-point scoring system in small areas of anterior junctions of basal, mid, and apical short axis views in addition to a conventional 17-segment model. All patients were prospectively followed for sudden death, cardiovascular death and hospitalization for heart failure or stroke associated with atrial fibrillation. Cardiovascular events occurred in 10 patients during an average follow-up period of 5.7 years. Stress and rest scores from anterior junction, and conventional summed stress score were significantly higher in patients with cardiovascular events than without (all P < 0.05). Anterior junction stress score of >2 produced a sensitivity of 50% and a specificity of 98% for cardiovascular events and was an independent predictor (hazard ratio 8.33; 95% confidence interval, 1.61-43.5; P = 0.01), with rest scores producing similar values, which were higher than summed stress score of >8 (5.68; 1.23-26.3; P = 0.03). The absence of myocardial perfusion abnormality in the narrow area of anterior junction differentiated HCM patients with low-risk. |
14,571 | [Direct current cardioversion in Abidjan: report of a ten-year practice in Institute of Cardiology of Abidjan, Ivory Coast]. | Direct current cardioversion is effective in arrhythmias' termination. Few is known about its use in our practice. This work aims to report its outcomes over a ten-year period in Abidjan.</AbstractText>One thousand, three hundred and ninety one charts of arrhythmic patients were reviewed.</AbstractText>Cardioversion was attempted in 102 patients. One hundred and eighty one shocks were delivered with a mean energy of 262, 1 joules. Success occurred in 84 patients (82,3%). Cardioversion failed in 18 patients mostly in atrial fibrillation. Eight serious complications (7,8%) occurred including 1 sinus node dysfunction, 1 pulmonary oedema, 1 metrorrhagia, 2 stroke, 1 pulmonary embolism. Two patients with ventricular tachycardia died of end-stage heart failure and aftermath of a mitral valve surgery.</AbstractText>Direct current cardioversion is effective and safe in our practice. Complications are predominantly due to the medical environment such as antiarrhythmic drugs use or clinical conditions.</AbstractText>© 2011 Société Française de Pharmacologie et de Thérapeutique.</CopyrightInformation> |
14,572 | Risk factors for persistent atrial fibrillation following successful hyperthyroidism treatment with radioiodine therapy. | To investigate the predicting factors for persistent atrial fibrillation (AF) following radioiodine therapy for hyperthyroidism.</AbstractText>Standard 12-lead ECG and 24-h Holter monitoring were performed in 94 patients (38 males, mean age 46.1±8.2 years) with persistent AF following radioiodine therapy for hyperthyroidism. Left ventricular (LV) function was assessed with two-dimensional echocardiography.</AbstractText>Euthyroidism or hypothyroidism was achieved in 81% and 19% of the patients, respectively, after radioiodine therapy. At the end of follow-up (1.6±1.3 years), LV ejection fraction in the 52 patients with LV dysfunction was increased from 39.3±3.3% to 59.0±5.5% (p<0.01). In the 38 patients with pre-treatment paroxysmal AF, no AF was documented during the follow-up. In the 45 patients with pre-treatment persistent AF, AF was found in 27 (60%) during the follow-up. Multivariate logistic regression analysis showed that more than 55 years old in age (RR 2.76, 95% CI: 1.16-8.79, p<0.01), duration of hyperthyroidism (RR 3.08, 95% CI: 1.22-11.41, p<0.01) and duration of pre-treatment atrial fibrillation (RR 2.96, 95% CI: 1.31-7.68, p<0.01) were independent predictors for persistent AF following radioiodine therapy.</AbstractText>Older age, duration of hyperthyroidism and pre-treatment duration of AF are risk factors for persistent AF following radioiodine therapy.</AbstractText> |
14,573 | Relationship of fragmented QRS with prognostic markers and in-hospital MACE in patients undergoing CABG. | Fragmented QRS complex (fQRS) is associated with increased morbidity and mortality, sudden cardiac death and recurrent cardiovascular events. However, its prognostic role has not been studied comprehensively in patients undergoing coronary artery bypass graft (CABG) surgery. In this study, we investigated the relationship between the presence of fQRS, and the prognostic markers and in-hospital major adverse cardiovascular events (MACE).</AbstractText>Two hundred and forty two eligible patients who underwent CABG surgery at our institution were enrolled consecutively. In analysis of fragmentations on electrocardiograms, presence of fQRS was defined as various RSR' patterns (≥ 1 R' or notching of S wave or R wave) with or without Q waves without a typical bundle-branch block in two contiguous leads corresponding to a major coronary artery territory. MACE was defined as cardiac death, recurrent myocardial infarction, heart failure, cerebrovascular event, sustained ventricular tachycardia or fibrillation.</AbstractText>Patients with fragmented QRS had older age (64 ± 10 vs. 61 ± 9 years, p = 0.03), prolonged QRS time (99 ± 11 vs. 87 ± 11 ms, p < 0.001), higher rate of Q wave on ECG (29% vs. 12%, p = 0.001), higher European system for cardiac operative risk evaluation (EUROSCORE) (4.0 ± 1.9 vs. 2.6 ± 1.6, p < 0.001) and lower left ventricular ejection fraction (LVEF)% (43 ± 12 vs. 60 ± 12, p < 0.001) in comparison to patients with non-fragmented QRS. In addition, the patients with fQRS had longer cross-clamp time (67 ± 23 vs. 55 ± 20 minutes, p = 0.001) and extracorporeal circulation (105 ± 31 vs. 91 ± 30 minutes, p = 0.003), increased inotropic usage (p < 0.001) and prolonged cardiac surgery intensive care unit (53 ± 25 vs. 35 ± 12 hours, p < 0.001) and in-hospital stay after CABG.</AbstractText>FQRS may have additional value in the assessment of cardiac function and in prediction of intra- and post-operative hemodynamic instability and adverse cardiovascular events. Fragmentations on admission ECG may be useful for identifying patients with higher risk who will need additional support after CABG surgery.</AbstractText> |
14,574 | Evaluation of coronary blood flow velocity during cardiac arrest with circulation maintained through mechanical chest compressions in a porcine model. | Mechanical chest compressions (CCs) have been shown capable of maintaining circulation in humans suffering cardiac arrest for extensive periods of time. Reports have documented a visually normalized coronary blood flow during angiography in such cases (TIMI III flow), but it has never been actually measured. Only indirect measurements of the coronary circulation during cardiac arrest with on-going mechanical CCs have been performed previously through measurement of the coronary perfusion pressure (CPP). In this study our aim was to correlate average peak coronary flow velocity (APV) to CPP during mechanical CCs.</AbstractText>In a closed chest porcine model, cardiac arrest was established through electrically induced ventricular fibrillation (VF) in eleven pigs. After one minute, mechanical chest compressions were initiated and then maintained for 10 minutes upon which the pigs were defibrillated. Measurements of coronary blood flow in the left anterior descending artery were made at baseline and during VF with a catheter based Doppler flow fire measuring APV. Furthermore measurements of central (thoracic) venous and arterial pressures were also made in order to calculate the theoretical CPP.</AbstractText>Average peak coronary flow velocity was significantly higher compared to baseline during mechanical chests compressions and this was observed during the entire period of mechanical chest compressions (12 - 39% above baseline). The APV slowly declined during the 10 min period of mechanical chest compressions, but was still higher than baseline at the end of mechanical chest compressions. CPP was simultaneously maintained at > 20 mmHg during the 10 minute episode of cardiac arrest.</AbstractText>Our study showed good correlation between CPP and APV which was highly significant, during cardiac arrest with on-going mechanical CCs in a closed chest porcine model. In addition APV was even higher during mechanical CCs compared to baseline. Mechanical CCs can, at minimum, re-establish coronary blood flow in non-diseased coronary arteries during cardiac arrest.</AbstractText> |
14,575 | Renin-Angiotensin System and AtrialFibrillation:Understanding the Connection. | Atrial fibrillation (AF) arises as a result of a complex interaction of triggers, perpetuators and the substrate. The recurrence of AF may be partially related to a biologic phenomenon known as remodeling, in which the electrical, mechanical, and structural properties of the atrial tissue and cardiac cells are progressively altered,creating a more favorable substrate. Atrial remodeling is in part a consequence of arrhythmia itself. Therefore,to prevent and to treat AF, much attention has been directed to upstream therapies to alter the arrhythmia substrate and to reduce atrial remodeling. The renin-angiotensin-aldosterone system (RAAS) plays a keyrole in these strategies. In this review we analyze the experimental and clinical evidence regarding the efficacy of RAAS inhibitors in AF treatment. In the primary prevention of AF, meta-analyses have shown that risk of new-onset AF in patients with congestive heart failure and left ventricular dysfunction is reduced by RAAS inhibitors, whereas in hypertensive and post-myocardial infarction patients, the results are less evident. In the secondary prevention of AF, some large, prospective, randomized, placebo-controlled studieswith angiotensin II-receptor blockers returned negative results. Unfortunately, the approach of using RAASinhibitors as antiarrhythmic drugs to prevent both new-onset and recurrent AF is in decline because negativetrial results are accumulating, with the exception of the results in patients with congestive heart failure. |
14,576 | Evolution of activation patterns during long-duration ventricular fibrillation in pigs. | Quantitative analysis has demonstrated five temporal stages of activation during the first 10 min of ventricular fibrillation (VF) in dogs. To determine whether these stages exist in another species, we applied the same analysis to the first 10 min of VF recorded in vivo from two 504-electrode arrays, one each on left anterior and posterior ventricular epicardium in six anesthetized pigs. The following descriptors were continuously quantified: 1) number of wavefronts, 2) wavefront fractionations, 3) wavefront collisions, 4) repeatability, 5) multiplicity index, 6) wavefront conduction velocity, 7) activation rate, 8) mean area activated by the wavefronts, 9) negative peak rate of voltage change, 10) incidence of breakthrough/foci, 11) incidence of block, and 12) incidence of reentry. Cluster analysis of these descriptors divided VF into four stages (stages i-iv). The values of most descriptors increased during stage i (1-22 s after VF induction), changed quickly to values indicating greater organization during stage ii (23-39 s), decreased steadily during stage iii (40-187 s), and remained relatively unchanged during stage iv (188-600 s). The epicardium still activated during stage iv instead of becoming silent as in dogs. In conclusion, during the first 10 min, VF activation can be divided into four stages in pigs instead of five stages as in dogs. Following a 16-s period during the first minute of VF when activation became more organized, all parameters exhibited progressive decreased organization. Further studies are warranted to determine whether these changes, particularly the increased organization of stage ii, have clinical consequences, such as alteration in defibrillation efficacy. |
14,577 | Safety and efficacy of the remote magnetic navigation for ablation of ventricular tachycardias--a systematic review. | Remote magnetic navigation (RMN) is considered to be a solution for mapping and ablation of several arrhythmias. In this systematic review we aimed to assess the safety and efficacy of RMN in ablation of ventricular tachycardia (VT).</AbstractText>The National Library of Medicine's PubMed database was searched for articles containing any of a predetermined set of search terms that were published prior to November 1, 2011. Quality of evidence was rated using the GRADE system.</AbstractText>The database search resulted in 11 relevant articles evaluating the usefulness of RMN. Three groups of VTs were studied: VT in patients with ischemic cardiomyopathy (ICMP), non-ischemic cardiomyopathy (NICMP) and structurally normal hearts (SNH). The use of RMN in patients with ICMP has been associated with success rates ranging from 71 to 80%. RMN has been shown to be a feasible and effective method for ablation of VT in NICMP and SNH patients. Success rates between 50% and 100% have been reported in NICMP populations. Rates ranging from 86% to 100% have been reported for SNH patients. The lowest rates of arrhythmia recurrence are reported for SNH patients (0-17%). In ICMP and NICMP, recurrence rates of 0-30% and 14-50%, respectively, have been reported. One patient experienced total heart block, and one patient experienced a thromboembolic event after RMN catheter ablation procedures.</AbstractText>RMN has been shown to be an effective and safe method for ablation of VT in various patient populations with low recurrence and complication rates. However, more comparative and randomized studies are necessary, and therefore the true value of RMN for VT ablation remains still unknown.</AbstractText> |
14,578 | TASK-1 channels may modulate action potential duration of human atrial cardiomyocytes. | <AbstractText Label="BACKGROUND/AIMS" NlmCategory="OBJECTIVE">Atrial fibrillation is the most common arrhythmia in the elderly, and potassium channels with atrium-specific expression have been discussed as targets to treat atrial fibrillation. Our aim was to characterize TASK-1 channels in human heart and to functionally describe the role of the atrial whole cell current I(TASK-1).</AbstractText>Using quantitative PCR, we show that TASK-1 is predominantly expressed in the atria, auricles and atrio-ventricular node of the human heart. Single channel recordings show the functional expression of TASK-1 in right human auricles. In addition, we describe for the first time the whole cell current carried by TASK-1 channels (I(TASK-1)) in human atrial tissue. We show that I(TASK-1) contributes to the sustained outward current I(Ksus) and that I(TASK-1) is a major component of the background conductance in human atrial cardiomyocytes. Using patch clamp recordings and mathematical modeling of action potentials, we demonstrate that modulation of I(TASK-1) can alter human atrial action potential duration.</AbstractText>Due to the lack of ventricular expression and the ability to alter human atrial action potential duration, TASK-1 might be a drug target for the treatment of atrial fibrillation.</AbstractText>Copyright © 2011 S. Karger AG, Basel.</CopyrightInformation> |
14,579 | Immediate coronary angiogram in comatose survivors of out-of-hospital cardiac arrest--an Australian study. | The role of immediate coronary angiography and percutaneous coronary intervention (angio±PCI), amongst comatose survivors of out-of-hospital cardiac arrest is unclear. This study was undertaken to evaluate if immediate angio±PCI compared to no initial intervention improves neurological outcome at hospital discharge amongst comatose survivors of out-of-hospital pulseless ventricular tachycardia (pVT) or ventricular fibrillation (VF).</AbstractText>All patients admitted to Intensive Care Unit (ICU) following an out-of-hospital VF/pVT arrest from 1/1/2003 to 31/12/2008 were included. Outcome of patients who underwent immediate angio±PCI was compared to those who did not undergo any intervention before admission to ICU. Good outcome was defined as survival to hospital discharge with Cerebral Performance Category (CPC) score of 1 or 2.</AbstractText>Thirty-five patients (30 Males, 5 Females, mean age 60.3±10.1), underwent angio±PCI prior to ICU admission. A further 35 patients (20 Males, 15 Females, mean age 61.1±17.6 years) were admitted directly to ICU without undergoing any intervention. Forty percent (14/35) of patients who had immediate coronary intervention survived to hospital discharge with a good outcome compared to 31% (11/35) patients who did not undergo any intervention. After adjusting for other covariates, the probability of good outcome at hospital discharge was related to severity of illness (SAPS-II) score at ICU admission (adj OR=0.87, 95% CI 0.81-0.94, p<0.01). Immediate angio±PCI compared to no intervention was associated with an improved outcome but this difference was statistically not significant (adj OR 1.32, 95% CI 0.26-7.87, p=0.78).</AbstractText>Immediate angio±PCI in comatose survivors of out-of-hospital VF/pVT arrest did not lead to better neurological outcome at hospital discharge.</AbstractText>Crown Copyright © 2011. Published by Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
14,580 | Modifications in ventricular fibrillation and capture capacity induced by a linear radiofrequency lesion. | An analysis was made of the effects of a radiofrequency-induced linear lesion during ventricular fibrillation and the capacity to capture myocardium through high-frequency pacing.</AbstractText>Using multiple epicardial electrodes, ventricular fibrillation was recorded in 22 isolated perfused rabbit hearts, analyzing the activation maps upon applying trains of stimuli at 3 different frequencies close to that of the arrhythmia: a) at baseline; b) after radio-frequency ablation to induce a lesion of the left ventricular free wall (length=10 [1] mm), and c) after lengthening the lesion (length=23 [2] mm).</AbstractText>Following lesion induction, the regularity of the recorded signals decreased and significant variations in the direction of the activation fronts were observed. On lengthening the lesion, there was a slight increase in the episodes with at least 3 consecutive captures when pacing at cycles 10% longer than the arrhythmia (baseline: 0.6 [0.7]; initial lesion: 1 [1], no significant differences; lengthened lesion: 3 [2.8]; P<.001), while a decrease was observed in those obtained upon pacing at cycles 10% shorter than the arrhythmia.</AbstractText>The radio-frequency -induced lesion increases the heterogeneity of myocardial activation during ventricular fibrillation and modifies arrival of the activation fronts in the adjacent zones. High-frequency pacing during ventricular fibrillation produces occasional captures during at least 3 consecutive stimuli. The lengthened lesion in turn slightly increases capture capacity when using cycles slightly longer than the arrhythmia.</AbstractText>Copyright © 2011 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.</CopyrightInformation> |
14,581 | Impact of periprocedural atrial fibrillation on short-term clinical outcomes following percutaneous coronary intervention. | There are few data on the incidence and clinical outcomes of patients with atrial fibrillation (AF) treated in the era of percutaneous coronary intervention (PCI). We analyzed 30-day clinical outcomes in 3,307 consecutive patients with and without AF (sinus rhythm) undergoing PCI from January 2007 through December 2008 enrolled in a multicenter Australian registry. Periprocedural AF was present in 162 patients (4.9%). AF was associated with older age (74.1 ± 8.9 vs 63.9 ± 11.9 years, p <0.001), higher baseline serum creatinine (0.13 ± 0.14 vs 0.10 ± 0.13 mmol/L, p = 0.01), and lower left ventricular ejection fraction (49.5 ± 13.2% vs 53.4% ± 11.6%, p <0.001). Significantly more patients with AF had a history of heart failure and cerebrovascular and peripheral arterial diseases (p ≤0.01 for all comparisons). Periprocedural glycoprotein IIb/IIIa inhibitor (31.5% vs 31.4%, p = 0.98) and antithrombin use were not different between groups, but in-hospital bleeding complications were higher in patients with AF (5.0% vs 2.1%, p = 0.015). Fewer patients with AF received drug-eluting stents (p = 0.004). AF was associated with a greater than fourfold increase in 30-day mortality (9.9% vs 2.2%, p <0.0001) and readmission rates at 30 days (p = 0.01). Fewer patients with AF were on dual antiplatelet therapy at 30 days (86.3% vs 94.3%, p <0.0001), although 28.1% of patients with AF were on triple therapy (dual antiplatelet therapy plus oral anticoagulation). In conclusion, patients with periprocedural AF represent a very high-risk group. Excess 30-day morbidity and mortality after PCI may be due to the higher incidence of co-morbidities, bleeding complications, and suboptimal antiplatelet therapy. |
14,582 | Effect of chest compressions on ventricular activation. | External mechanical forces can cause ventricular capture and fibrillation (i.e., commotio cordis). In animals, we showed that chest compressions (CCs) can also cause the phenomenon. The aim of the present study was to determine whether ventricular capture by CCs occurs in humans. Electronic rhythm strips were analyzed in 31 cases of out-of-hospital cardiac arrest. The timing of the CCs was identified from the changes in thoracic impedance between the defibrillator pads. Ventricular capture was defined as QRS complexes of similar morphology occurring intermittently but synchronized with the CC artifact and impedance waveform. Only intermittent ventricular capture was identified to avoid misclassifying constant motion artifacts or intrinsic rhythm as ventricular capture. Of the 29 patients who received CCs for ≥1 minute, minimal or stable motion artifact was present in 24. Intermittent ventricular capture was found in 7 of the 24 patients. In the patients with ventricular capture, the number of ventricular activations (from ventricular capture and native beats) was greater during the CCs than when the CCs was not being performed (18 ± 8.9 vs 9.7 ± 4.0 activations in 15 seconds, p = 0.01). However, in patients without ventricular capture, they were similar (6.8 ± 8.2 vs 7.2 ± 8.8 activations in 15 seconds, p = 0.47). Refibrillation occurred in 22 patients; it began during the CCs in 16 and closely following their initiation in 3. In conclusion, CCs during cardiopulmonary resuscitation can electrically stimulate the heart. Additional studies evaluating the effect of ventricular capture on cardiopulmonary resuscitation outcomes, its relation to refibrillation, and methods to prevent or time ventricular capture by CCs are warranted. |
14,583 | Focal initiation of sustained and nonsustained ventricular tachycardia in a canine model of ischemic cardiomyopathy. | To define the role of focal and reentrant mechanisms underlying nonsustained (NSVT) and sustained ventricular tachycardia (SuVT) induced by programmed stimulation, 3-dimensional cardiac mapping was performed in 8 dogs with heart failure (HF) created by multiple intracoronary microsphere embolizations.</AbstractText>Continuous recording from 232 intramural sites throughout the left and right ventricles and the interventricular septum was performed during programmed stimulation in the absence and presence of isoproterenol (Iso, 0.1 μg/kg/min). Sinus beats and the last extrastimuli preceding induced VT conducted with total activation times (TA) of 51 ± 10 and 111 ± 8 milliseconds, respectively, that did not change during Iso infusion (47 ± 4 and 109 ± 5 milliseconds, P = NS). NSVT was induced in 75% of HF dogs; SuVT was induced in 38%. In all cases, initiation and maintenance of SuVT and NSVT arose by a focal mechanism. Compared to NSVT, SuVT had a shorter coupling interval (CI; 150 ± 7 vs 186 ± 16, P < 0.05) and a predilection for certain critical subendocardial initiation sites (that were initiation sites for only 29% of NSVT beats). After 21-30 beats, acceleration of SuVT by a focal mechanism to a CI less than 120 milliseconds led to functional conduction delay (TA increasing from 111 ± 3 to 137 ± 3 milliseconds, P < 0.0001), intramural reentry, and transition to ventricular fibrillation.</AbstractText>Thus, initiation of SuVT in a model of ischemic HF is due to a focal mechanism. However, subsequent acceleration of this focal mechanism can ultimately lead to functional conduction delay and development of intramural reentry.</AbstractText>© 2011 Wiley Periodicals, Inc.</CopyrightInformation> |
14,584 | Watchful waiting for severe mitral regurgitation. | Watchful waiting is an established treatment strategy for asymptomatic patients with severe organic mitral regurgitation. It is based on indications for surgery that are based on current European Society of Cardiology and American Heart Association/American College of Cardiology guideline recommendations, which are defined by symptom onset, impairment of left ventricular function, and left ventricular enlargement. Excellent outcome is achieved when patients are periodically followed with clinical and echocardiographic examinations and when surgery is performed in expert centers. The strategy is based on the recognition of mitral regurgitation at an early symptomatic stage, avoiding a delayed referral of these patients. There is an ongoing debate about whether surgery should be performed in asymptomatic patients with preserved ventricular function. Ultimately, decision-making needs to be individualized and to take individual patient-related factors and local resources (including the natural history of the disease, the risk of surgery, and the likelihood of successful mitral valve repair) into consideration to obtain an optimal outcome with medical and surgical management. |
14,585 | Early post-cardiac surgery delirium risk factors. | The purpose of this study was to identify the post-cardiac surgery delirium risk factors and to evaluate clinical outcomes. Data on 90 patients with postoperative delirium after cardiac surgery on cardiopulmonary bypass (CPB) were analyzed retrospectively. The patients were divided into two groups by evaluating the severity of the delirium: light and moderate delirium group (n=74) and severe delirium group (n=16). We found that the rate of early post-cardiac surgery delirium was low (4.17%). We have determined that post-cardiac surgery delirium prolonged the length of stay in the Intensive Care Unit (ICU) by (8.4 (8.6)) and the hospital stay by (23.6 (13.0)) days. The patients had higher preoperative risk scores, their age was 71.5 (8.9) years, the body mass index was 28.8 (4.4) kg/m(2), the majority were male (72.2%), and the left ventricular ejection fraction was 46.1(11.9) %. Statistical analysis by multivariable logistic regression has indicated that increasing the dose of fentanyl administered during surgery over 1.4 mg also increased the possibility of developing a severe delirium (OR=29.4, CI 4.1-210.3) and longer aortic clamping time could be independently associated with severe postoperative delirium (OR=8.0, CI 1.7-37.2). After surgery, new atrial fibrillation (AF) episodes amounted to 53.3% and, after distinguishing the delirium severity groups, AF developed in the patients belonging to the severe delirium groups statistically significantly more frequently, 81.8 vs 47.3, where p=0.01. Our data suggest that early post-cardiac surgery delirium is not a common complication, but it prolonged the length of stay at the ICU and in the hospital. The delirium risk factors, such as longer aortic clamping time, the dose of fentanyl and new atrial fibrillation episodes occurring after cardiac surgery, are associated statistically significantly with the development of severe post-cardiac surgery delirium. |
14,586 | The management of patients with atrial fibrillation and dronedarone's place in therapy. | The pharmacologic management of atrial fibrillation (AF) includes rate and rhythm control strategies. Antiarrhythmic agents (eg, amiodarone, flecainide, and propafenone) are limited by serious toxicities (including proarrhythmic effects and pulmonary toxicity), which may lead to a reduced net clinical efficacy of rhythm control strategies. Dronedarone, a new antiarrhythmic agent, is effective in the maintenance of sinus rhythm. Dronedarone has also been shown to reduce ventricular rate and the incidence of hospitalization due to cardiovascular events. Dronedarone is recommended by the 2011 American College of Cardiology Foundation/American Heart Association/Heart Rhythm Society guidelines update for the management of AF patients with no or minimal heart disease, coronary artery disease, and hypertension with no left ventricular hypertrophy. Dronedarone is contraindicated in patients with New York Heart Association (NYHA) class IV heart failure or NYHA class II-III heart failure with a recent decompensation requiring hospitalization or referral to a specialized heart failure clinic. |
14,587 | A novel variant in plakophilin-2 gene detected in a family with arrhythmogenic right ventricular cardiomyopathy. | Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by fibrofatty replacement of muscular fibers predominantly in the right ventricle and with ventricular arrhythmias as the main clinical manifestation. Mutations in several components of the desmosome genes have been identified and mutations of the plakophilin-2 (PKP-2) gene are a common cause of ARVC. The aim of this study is to investigate the correlation between genotype and phenotype in a family with a novel PKP-2 variant.</AbstractText>This study describes the clinical findings and genetic analysis in a family with ARVC. A part of the family has been followed clinically long term for up to 27 years. Two not previously reported PKP-2 variants (L506P and T526A) have been identified in this family. Even though all members of this family share the novel variant L506P, the clinical features, i.e., their phenotypes are different. The L506P variant is located in exon 7 and affects a highly conserved residue. The same amino acid, leucine, is present in all species evaluated, indicating a functional importance and the variant is predicted to be damaging. The novel L506P variant in the PKP-2 gene is thus a possible pathogenic alteration in the described family with ARVC. In contrast, the T526A variant is weakly conserved and predicted to be tolerated.</AbstractText>While many of the reported ARVC mutations are truncating mutations, the possibly damaging variant found in this family, is a missense alteration affecting a highly conserved residue 506 located in exon 7.</AbstractText> |
14,588 | Actual situation regarding cardiac etiology determined by clinical diagnosis of and medical examiner's postmortem findings on witnessed out-of-hospital cardiac arrest cases. | To examine indicators that may assist in the diagnosis of cardiac etiology using simple tests in witnessed cardiac etiology out-of-hospital cardiac arrest cases, which is emphasized in the Utstein Style.</AbstractText>The subjects were 165 witnessed cardiac etiology out-of-hospital cardiac arrest cases, which were transported to Kobe University Hospital during the five-year period between January 1, 2005 and December 31, 2009. A comparative study was conducted into whether there were any significant differences in the initial electrocardiogram (ECG) and the various early diagnostic markers of acute myocardial infarction between the group who were finally diagnosed as being of cardiac etiology and the group who were finally diagnosed as being of non-cardiac etiology.</AbstractText>Of the 165 witnessed cardiac etiological cases, 69 cases were finally re-classified as non-cardiac etiological cases on the basis of scrutiny after admission or postmortem findings by the Medical Examiner. Ventricular fibrillation shown in the initial ECG and Qualitative cardiac troponin T test positive were significantly higher in the final diagnosis cardiac group than in the final diagnosis non-cardiac group. Ventricular fibrillation and troponin T positive can be seen as significant indicators in determining whether a case was cardiac or non-cardiac, and the model χ2 test result of p < 0.01 in the multiple logistic regression analysis was significant, and the determining predictive value was 65.4%.</AbstractText>The indicators which should be noted in simple tests to improve the precision of discrimination of cardiac etiology in out-of-hospital cardiac arrests are ventricular fibrillation in the initial ECG and the qualitative test of cardiac troponin T.</AbstractText> |
14,589 | Efficacy and safety of vernakalant in recent-onset atrial fibrillation after the European medicines agency approval: systematic review and meta-analysis. | Vernakalant is an emergent antiarrhythmic drug that, in preclinical studies, has demonstrated high efficacy in restoring sinus rhythm and safety in patients with rapid recent-onset atrial fibrillation. The aim of this work was to evaluate the efficacy and safety of vernakalant for cardioversion of recent-onset atrial fibrillation. PubMed, EMBASE, Clinical Trials Registry, and European Medicines Agency public reports were searched for randomized clinical trials, until May 2011, of vernakalant compared with controls (placebo/other antiarrhythmic drug) in enrolled patients with high ventricular rate atrial fibrillation. Five randomized trials that met inclusion criteria enrolled a total of 1099 patients. Among these, 810 had recent-onset atrial fibrillation. When compared with controls (placebo/other oral antiarrhythmic drugs), vernakalant was associated with a significant increase in cardioversion within 90 minutes from drug infusion (relative risk, 8.4; 95% confidence interval, 4.4-16.3; P < .00001). Compared with controls, vernakalant was not associated with a significant difference in serious adverse events (relative risk, 0.9; 95% confidence interval, 0.6-1.4; P = .64). The authors conclude that compared with controls, vernakalant is effective and safe for rapidly converting recent-onset atrial fibrillation. Questions remain surrounding safety because 1 unpublished trial was discontinued for this reason. Further cost-effective analysis and comparison with other antiarrhythmic agents, such as class I antiarrhythmic agents, should be investigated, especially in the emergency department. |
14,590 | Pulmonary venous evaluation using electrocardiogram-gated 64-detector row cardiac CT. | Radiofrequency ablation of the pulmonary veins is an accepted treatment for atrial fibrillation. An accurate knowledge of pulmonary venous anatomy and dimensions is desirable prior to such a procedure. The objective of this study was to use 64-detector row cardiac CT to investigate the changes in pulmonary venous dimensions during the cardiac cycle.</AbstractText>Data from 44 consecutive patients with no significant cardiovascular pathology who underwent electrocardiogram (ECG)-gated 64-detector row coronary angiography were retrospectively analysed. Average diameter and cross-sectional area were measured at 5 mm intervals from each pulmonary vein ostium, in ventricular end-diastole and ventricular end-systole, using curved multiplanar reformats.</AbstractText>4 (9.1%) patients had pulmonary vein anomalies and were excluded. In the remaining 40 patients, pulmonary vein diameter and area at the ostium were significantly larger in end-systole in all four veins, with the largest differences in the superior pulmonary veins. Dimensional changes for diameter (millimetres) and area (square millimetres) were as follows: left superior pulmonary vein, 2.5 (p<0.001), 65.48 (p<0.001); right superior pulmonary vein, 1.63 (p<0.001), 56.27 (p<0.001); left inferior pulmonary vein, 1.1 (p<0.001), 30.41 (p<0.001); and right inferior pulmonary vein, 0.68 (p=0.005), 30.14 (p=0.005). Less marked changes were seen at measurement sites further from the atrium. Interobserver correlation was high (all but one measurement >0.9).</AbstractText>Pulmonary vein dimensions change significantly between end-systole and end-diastole, and the ostia of the superior pulmonary veins are potentially the most vulnerable to dimensional inaccuracies. ECG-gated cardiac CT may provide a more precise method of pulmonary venous dimensional measurement than non-gated techniques. Knowledge of change in pulmonary vein diameter offers interesting potential research into the effect of pulmonary vein function.</AbstractText> |
14,591 | Did you know? Why amiodarone requires diligent monitoring? | Amiodarone remains one of the most commonly prescribed antiarrhythmics effectively treating atrial fibrillation and ventricular arrhythmias. Diligent monitoring for potentially serious side effects especially in the elderly is paramount. |
14,592 | Current evidence in therapeutic hypothermia for postcardiac arrest care. | The ring of the red notification phone breaks the relative calm of an otherwise typical Monday morning and heralds the arrival of a critically ill patient. The dispatcher announces that EMS is on the way with a 57-year-old man in cardiac arrest, with an ETA of 3 minutes. Shortly after preparations for their arrival are complete, EMS personnel enter with CPR in progress and the patient already intubated. As monitor/defibrillator attachment, ETT placement confirmation, additional IV access, and complete exposure of the patient occur, you hear more about the clinical scenario from EMS. Mr. I.C. is a 57-year-old male who was moving furniture when, as described by witnesses, he complained of difficulty catching his breath and a slight tightness in his chest. He began coughing violently, vomited once, gasped, and collapsed. Emergency medical services personnel state that they arrived approximately 20 minutes after the patient had collapsed, with CPR in progress. The patient was intubated in the field, and EMS reports that the initial rhythm was PEA. Upon the patient's arrival in the ED, the rhythm is noted to be ventricular fibrillation. Defibrillation is attempted twice over the next 4 minutes, with concomitant administration of medications. During the next rhythm check, QRS complexes are noted on the monitor and a pulse is palpated. The patient has had a return of spontaneous circulation, apparently 50 minutes from onset of the arrest. As you initiate postresuscitation care, you consider the patient's prognosis and wonder if he qualifies for therapeutic hypothermia; ie, will therapeutic hypothermia make a difference in his outcome? |
14,593 | Sudden cardiac arrest: associated with anomalous origin of the right coronary artery from the left main coronary artery. | Anomalous origin of the coronary artery from the opposite sinus of Valsalva and a course of that artery between the ascending aorta and the pulmonary artery is a rare congenital anomaly. It can cause myocardial ischemia, syncope, and sudden cardiac death in young people. Herein, we report the case of a 24-year-old man who was brought to our hospital after cardiac arrest due to ventricular fibrillation. Emergent coronary angiography revealed that the left coronary artery was normal; however, the right coronary artery originated at the left sinus of Valsalva. After admission, the patient was treated with mild therapeutic hypothermia for 48 hours and had a favorable neurologic recovery. Subsequent 16-slice multidetector computed tomography revealed that the right coronary artery arose from the left main coronary artery, took an intramural course, and was severely compressed between the ascending aorta and the pulmonary artery. The patient underwent direct implantation of the anomalous artery into the correct aortic sinus. Histologic specimens from the proximal end of the right coronary artery showed an intramural segment with intimal fibrous thickening, fragmentation and random arrangement of the elastic fiber, degeneration of the medial smooth-muscle cells, and an increase in the medial stromal substance. Postoperatively, repeat coronary angiography with provocation testing for coronary spasm revealed no myocardial ischemic change. The patient recovered uneventfully. We found that cardiac multidetector computed tomography was useful in evaluating the cause of the sudden cardiac arrest, identifying the anomalous coronary artery, and helping to guide the surgical decisions. |
14,594 | [Autonomic dysfunction and cardiac arrhythmia in patients with obstructive and central sleep apnea]. | Obstructive sleep apnea and central sleep apnea with Cheyne-Stokes respiration are associated with an increased risk of cardiac arrhythmia. Apnea- associated arrhythmia may contribute to sudden cardiac death and premature mortality in those patients. Both forms of sleep apnea excert strong modulatory effects on the autonomic system with a special autonomic profile. Profound vagal activity is leading to bradyarrhythmias, and sypathico-excitation to tachyarrhythmias. Atrial fibrillation and ventricular arrhythmias in obstructive and central sleep apnea patients are mainly found in combination with cardiovascular comorbidity (coronary heart disease, hypertensive heart disease, chronic heart failure). Bradyarrhythmias in OSA are induced by a cardioinhibitory vagal reflex due to obstructed airway. CPAP-therapy has been demonstrated to reduce arrhythmias. |
14,595 | Impact of chronic atrial fibrillation in patients with severe heart failure and indication for CRT: data of two registries with 711 patients (1999-2006 and 2007-6/2008). | Atrial fibrillation (AF) is a relevant comorbidity in heart failure (HF) patients. In milestone cardiac resynchronization therapy (CRT) studies, patients with AF were excluded. We sought to investigate the influence of chronic atrial fibrillation (AF) on patients with CRT. AV node (AVN) ablation is frequently recommended. Converting AF to sinus rhythm (SR) is not a standard concept.</AbstractText>A total of 584 consecutive patients with CRT devices were included in a single-center registry from 1999-2006 (retrospective registry) and 127/324 patients from 2007-06/2008 (prospective registry). The impact of persistent AF (group 1) on clinical and echocardiographic improvement compared with patients in SR (group 2) after 12 (6) months follow-up were analyzed. Re-establishing SR after initial cardioversion or need for AVN ablation was examined.</AbstractText>In the retrospective registry, 139 (24%) patients presented with AF (group 1) and 445 with SR (group 2). The groups differed in age, gender, and left atrium (LA) size but not in NYHA class, ejection fraction (EF), left ventricular end-diastolic dimension (LVEDD), B-type natriuretic peptide (BNP) levels, QRS width, and underlying disease. After 1 year, CRT improvement of NYHA class and EF was similar with higher mortality in group 1 (12% vs. 7%; OR 1.80; 95% confidence interval 0.95-3.4). The AF group presented with SR in 33/82 (40%) patients and 11% needed AVN ablation. The prospective data showed 27 (21%) patients in AF with conversion to SR in 41% after 6 months.</AbstractText>Patients with severe HF and chronic AF had a comparable improvement with CRT as those in SR. CRT is a successful treatment option in patients with chronic AF offering the potential to restore SR in a significant number of patients.</AbstractText> |
14,596 | Is the coexistence of sustained ST-segment elevation and abnormal Q waves a risk factor for electrical storm in implanted cardioverter defibrillator patients with structural heart diseases? | The aim of this study was to determine whether or not the coexistence of sustained ST-segment elevation and abnormal Q waves (STe-Q) could be a risk factor for electrical storm (ES) in implanted cardioverter defibrillator (ICD) patients with structural heart diseases.</AbstractText>In all, 156 consecutive patients received ICD therapy for secondary prevention of sudden cardiac death and/or sustained ventricular tachyarrhythmias were included. Electrical storm was defined as ≥3 separate episodes of ventricular tachycardia (VT) and/or ventricular fibrillation (VF) terminated by ICD therapies within 24 h. During a mean follow-up of 1825 ± 1188 days, 42 (26.9%) patients experienced ES, of whom 12 had coronary artery disease, 15 had idiopathic dilated cardiomyopathy, 6 had hypertrophic cardiomyopathy, 4 had arrhythmogenic right ventricular cardiomyopathy, 4 had cardiac sarcoidosis, and 1 had valvular heart disease. Sustained ST-segment elevation and abnormal Q waves in ≥2 leads on the 12-lead electrocardiography was observed in 33 (21%) patients. On the Kaplan-Meier analysis, patients with STe-Q had a markedly higher risk of ES than those without STe-Q (P< 0.0001). The multivariate Cox proportional hazards regression model indicated that STe-Q and left ventricular ejection fraction (LVEF) (<30%) were independent risk factors associated with the recurrence of VT/VF (STe-Q: HR 1.962, 95% CI 1.24-3.12, P= 0.004; LVEF: HR 1.860, 95% CI 1.20-2.89, P= 0.006), and STe-Q was an independent risk factor associated with ES (HR 4.955, 95% CI 2.69-9.13, P< 0.0001).</AbstractText>Sustained ST-segment elevation and abnormal Q waves could be a risk factor of not only recurrent VT/VF but also ES in patients with structural heart diseases.</AbstractText> |
14,597 | Validating the acute heart failure index for patients presenting to the emergency department with decompensated heart failure. | The acute heart failure index (AHFI) is a previously derived prediction rule to identify patients presenting to emergency departments (ED) with decompensated heart failure (DHF) at low risk of early life-threatening events.</AbstractText>To validate the AHFI prospectively.</AbstractText>Using a prospective cohort study, adult patients presenting to an urban university hospital ED with DHF were included. Data on 21 variables were gathered to calculate the AHFI. Primary endpoints included inpatient death and non-fatal serious outcomes (myocardial infarction, ventricular fibrillation, cardiogenic shock, cardiac arrest, intubation, or cardiac reperfusion). Secondary endpoints included death from any cause or readmission for heart failure within 30 days. Primary and secondary endpoint rates were calculated with 95% CI for the low and higher-risk subgroups.</AbstractText>259 patients were enrolled. 245/259 (95%) were admitted. 60/259 (23%) met low-risk criteria, of whom 1/60 (1.7%, CI 0.04 to 8.9) was discharged after sustaining pulseless electrical activity arrest. The comparable primary outcome rate in the derivation study was 1.4% (CI 1.1 to 1.7). 17/199 (8.5%, CI 5.1 to 13.3) higher-risk patients experienced an endpoint, compared with 13.3% (CI 12.9 to 13.7) in the derivation cohort. One low-risk patient (1.7%, CI 0.04 to 8.9) died within 30 days, and five (8.3%, CI 2.8 to 18.4) were readmitted. Corresponding rates in the derivation study were 2% and 5%, respectively.</AbstractText>The results are consistent with those previously reported for the low-risk subgroup of the AHFI. Further research is needed to determine the impact, safety and full range of generalisability of the AHFI as an adjunct to decision making.</AbstractText> |
14,598 | Cardiac arrest and the 2010 advanced cardiac life support guidelines--part IV. | The chance of a successful outcome with any cardiac arrest is prompt initiation of hands-only compression at a rate of at least 100 per min, to a depth of 2 in.,with full chest recoil, and no more than a 10-s interruption of compressions. The priority, regardless of being in a private clinic or in a facility using a team approach,is to start compressions and maintain effective compressions with minimal interruptions. Most cardiac arrests are related to ventricular fibrillation and the chance of successfully defibrillating this rhythm is highest at the beginning of the arrest. For every minute a patient is in ventricular fibrillation, his or her chance of survival greatly decreases (Traverset al., 2010). This is why it is extremely important to defibrillate immediately. Once a patient has return of spontaneous circulation,postresuscitation care needs to be implemented. The biggest reason for a patient to develop ventricular fibrillation is an acute coronary syndrome, and this is why the new guidelines have outlined transferring a post arrest patient to a cardiac catheterization laboratory to perform an emergency angiogram and angioplasty. Part of this post arrest management also includes therapeutic hypothermia in those patients who remain comatose after return of spontaneous circulation. This article has reviewed a case study of a postoperative patient who developed ventricular fibrillation and the priorities of care according to the 2010 ACLS guidelines. Watch for more ACLS-based case studies in upcoming articles. |
14,599 | Investigating the role of the coronary vasculature in the mechanisms of defibrillation. | The direct role of coronary vessels in defibrillation, although hypothesized to be important, remains to be elucidated. We investigated how vessel-induced virtual electrode polarizations assist reentry termination.</AbstractText>A highly anatomically detailed rabbit ventricular slice bidomain computer model was constructed from 25-μm magnetic resonance data, faithfully representing both structural and electric properties of blood vessels. For comparison, an equivalent simplified model with intramural cavities filled in was also built. Following fibrillation induction, 6 initial states were selected, and biphasic shocks (5-70 V) were applied using a realistic implanted cardioverter-defibrillator electrode configuration. A fundamental mechanism of biphasic defibrillation was uncovered in both models, involving successive break excitations (after each shock phase) emanating from opposing myocardial surfaces (in septum and left ventricle), which rapidly closed down excitable gaps. The presence of vessels accelerated this process, achieving more-rapid and successful defibrillation. Defibrillation failed in 5 cases (all because of initiation of new activity) compared with 8 with the simplified model (5/8 failures because of surviving activity). At stronger shocks, virtual electrodes formed around vessels, rapidly activating intramural tissue because of break excitations, assisting the main defibrillation mechanism, and eliminating all activity <15 ms of shock end in 60% of successful shocks (36% in simplified model). Subsequent analysis identified that only vessels >200 μm in diameter participated through this mechanism. Consequently, wavefronts could survive intramurally in the simplified model, leading to reentry and shock failure.</AbstractText>We provide new insight into defibrillation mechanisms by showing how intramural blood vessels facilitate more-effective elimination of existing wavefronts, rapid closing down of excitable gaps, and successful defibrillation and give guidance toward the required resolution of cardiac imaging and model generation endeavors for mechanistic defibrillation analysis.</AbstractText> |
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