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5,200 | The autonomic nervous system in cardiac electrophysiology: an elegant interaction and emerging concepts. | The autonomic nervous system plays an integral role in the modulation of normal cardiac electrophysiology. This is achieved via a complex network of pre- and postganglionic sympathetic and parasympathetic fibers that synapse on extrinsic and intrinsic cardiac ganglia and ultimately directly innervate cardiac myocytes. Alterations in autonomic tone may induce changes in local cellular electrophysiology that may manifest clinically in a number of ways, ranging from changes in heart rate to changes in heart rhythm. These relationships between autonomic tone and the evolution of cardiac dysrhythmias are areas of evolving research, with increasing evidence for a key role for autonomic ganglia in the pathogenesis of atrial fibrillation and sympathetic nerves in the predilection toward ventricular tachycardia in areas of myocardial scar. In this review, we highlight what is known about the anatomy and physiology of the cardiac autonomic nervous system, the evidence supporting the relationship of autonomic tone to clinically significant arrhythmias, and a variety of mechanisms (eg, direct ion channel effects) and diagnostic tools that exist to help define this relationship. Further emphasized are potential future avenues of research needed to elucidate the relationship between changes in normal autonomic tone and the pathogenesis of cardiac arrhythmias. |
5,201 | The impact of rapid atrial pacing on ADMA and endothelial NOS. | The endothelial nitric oxide synthase (eNOS) inhibitor asymmetric dimethylarginine (ADMA) is a well-established risk factor for oxidative stress, vascular dysfunction, and congestive heart failure. The aim of the present study was to determine the impact of rapid atrial pacing (RAP) on ADMA levels and eNOS expression.</AbstractText>ADMA levels were studied in 60 age- and gender-matched patients. Thirty five patients had persistent atrial fibrillation (AF)≥ 4months. In AF-patients, parameters were studied before and 24h after electrical cardioversion. Moreover, ADMA, eNOS expression, and calcium-handling proteins were studied in pigs subjected to RAP as well as in endothelial cell (EC) cultures. ADMA level was significantly higher in AF compared to sinus rhythm patients (p=0.024). ADMA was highest in AF-patients, who also showed elevated troponin T (TnT) levels. Moreover, ADMA showed a significant linear correlation to TnT (r=0.47; p<0.01). After electrical cardioversion ADMA returned to normal within 24h. In pigs, RAP for 7h increased ADMA levels (p=0.018) and TnI (p<0.05), and reduced mRNA expression of ventricular and aortic eNOS (-80%; p<0.05) compared to sham-control. However, ADMA per se did not affect eNOS mRNA level in EC cultures.</AbstractText>The current study shows that acute and persistent episodes of atrial tachyarrhythmia are associated with elevated ADMA levels accompanied by increased ischemic myocardial markers. Moreover, RAP increases ADMA and down-regulates eNOS expression in an ADMA-independent manner. We conclude that the combination of these two separate and potentially synergistic mechanisms may contribute to long-term vascular injury during atrial tachyarrhythmia.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,202 | Domperidone and ventricular arrhythmia or sudden cardiac death: a population-based case-control study in the Netherlands. | Recently, a 4-fold increase in risk of sudden cardiac death (SCD) was reported for domperidone in a study that focused on corrected QT interval (QTc)-prolonging drugs as a class and their association with SCD.</AbstractText>To evaluate the association between the use of domperidone and serious non-fatal ventricular arrhythmia (VA) and SCD in the general population.</AbstractText>We performed a population-based, case-control study during 1996-2007 in the Integrated Primary Care Information (IPCI) database, a longitudinal general practice research database in the Netherlands. We included all patients aged ≥18 years without cancer in the source population. We studied the association between the use of domperidone by recency of use (current, past and none) and daily dose, and the risk of serious non-fatal VA or SCD. Cases were defined as a natural death due to cardiac causes heralded by abrupt loss of consciousness within 1 hour after the onset of acute symptoms or an unwitnessed, unexpected death of someone seen in a stable medical condition <24 hours previously with no evidence of a non-cardiac cause. Controls were randomly drawn from the source population and matched to cases on age, sex, practice and index date. We compared the exposure odds for SCD alone and VA plus SCD by means of conditional logistic regression while adjusting for all available confounders. In addition, we stratified by insurance type.</AbstractText>The study population comprised 1366 cases (62 VA and 1304 SCD) and 14114 matched controls. Of all cases, ten patients were current domperidone users at the index date, all with SCD. The matched unadjusted odds ratio of domperidone and SCD was 3.72 (95% CI 1.72, 8.08). Daily doses >30 mg were associated with a significant increased risk of SCD (adjusted odds ratio [OR(adj)] 11.4 [95% CI 1.99, 65.2]). Since there was a near interaction with health insurance (p = 0.050), all analyses were stratified by insurance. In publicly insured patients, seven cases were current users at the index date. Current use was associated with a significant increased risk of SCD (OR(adj) 4.17 [95% CI 1.33, 13.1]). Amongst privately insured patients there was one domperidone-exposed case, and amongst non-insured there were two.</AbstractText>Current use of domperidone, especially high doses, is associated with an increased risk of SCD. We could not demonstrate an effect of domperidone on non-fatal VA due to absence of exposed cases.</AbstractText> |
5,203 | Differential action of two prolactin isoforms on ischemia and re-perfusion-induced arrhythmias in rats in vivo. | The different influences of one of the PRL isoforms (PRL I) on the cardiovascular system have been described in the past.</AbstractText>Our goal was to establish an appropriate iv dose of 2 PRL isoforms (PRL I and PRL II) in intact rats. After establishing this dose, PRL I (0.01 mg/kg) or PRL II (0.001 mg/kg) was administered in bolus 10 min before left anterior descending coronary artery occlusion (7 min) followed by re-perfusion (15 min). We then aimed to study and compare the effects of these isoforms on ischemia- and re-perfusion-induced arrhythmias in the ischemia and re-perfusion-induced arrhythmias model in rats.</AbstractText>Mortality index, ventricular fibrillation and tachycardia (VF, VT) incidence and duration, systolic, diastolic, and mean arterial blood pressure, heart rate and myocardial index of oxygen consumption [pressure rate product (PRP)] were measured and calculated.</AbstractText>Both PRL isoforms reduced animal mortality (from 50 to 18.75 and 25%, respectively). PRL II significantly reduced VF incidence (to 25%) as well as VT duration (18.21 ± 3.09) and these effects were markedly different from PRL I and from the control group (p<0.05). Both PRL reduced PRP in the recovery phase (p<0.05).</AbstractText>We proved that supraphysiological doses of PRL isoforms administered in bolus could protect against sudden cardiac death as well as severe arrhythmias episodes during re-perfusion. Because of PRL's positive influence on the cardiovascular system and as an endogenous, well-tolerated substance, it might be of potential clinical use.</AbstractText> |
5,204 | Green tea extract given before regional myocardial ischemia-reperfusion in rats improves myocardial contractility by attenuating calcium overload. | There is evidence for a negative correlation between green tea consumption and cardiovascular diseases. The aim of the present study was to examine whether green tea extract (GTE) given before regional myocardial ischemia could improve depression of myocardial contractility by preventing cytosolic Ca(2+) overload. Regional ischemia-reperfusion (IR) was induced in rats by ligating the left anterior descending branch for 20 min, then releasing the ligature. Ligation induced ventricular arrhythmias in rats without GTE pretreatment, but decreased arrhythmogenesis was seen in rats pretreated 30 min earlier with GTE (400 mg/kg). During reperfusion, arrhythmias only occurred during the initial 5 min, and GTE pretreatment had no effect. After overnight recovery, serum cTnI levels were greatly increased in control post-IR rats but only slightly elevated in GTE-pretreated post-IR rats. Myocardial contractility measured by echocardiography was still depressed after 3 days in control post-IR rats, but not in GTE-pretreated post-IR rats. No myocardial ischemic injury was seen in post-IR rats with or without GTE pretreatment. Using freshly isolated single heart myocytes, GTE was found to attenuate the post-IR injury-associated cytosolic Ca(2+) overload and modulate changes in the levels and distribution of myofibril, adherens junction, and gap junction proteins. In summary, GTE pretreatment protects cardiomyocytes from IR injury by preventing cytosolic Ca(2+) overload, myofibril disruption, and alterations in adherens and gap junction protein expression and distribution. |
5,205 | Three-dimensional echocardiography using single-heartbeat modality decreases variability in measuring left ventricular volumes and function in comparison to four-beat technique in atrial fibrillation. | Three dimensional echocardiography (3DE) approaches the accuracy of cardiac magnetic resonance in measuring left ventricular (LV) volumes and ejection fraction (EF). The multibeat modality in comparison to single-beat (SB) requires breath-hold technique and regular heart rhythm which could limit the use of this technique in patients with atrial fibrillation (AF) due to stitching artifact. The study aimed to investigate whether SB full volume 3DE acquisition reduces inter- and intraobserver variability in assessment of LV volumes and EF in comparison to four-beat (4B) ECG-gated full volume 3DE recording in patients with AF.</AbstractText>A total of 78 patients were included in this study. Fifty-five with sinus rhythm (group A) and 23 having AF (group B). 4B and SB 3DE was performed in all patients. LV volumes and EF was determined by these two modalities and inter- and intraobserver variability was analyzed.</AbstractText>SB modality showed significantly lower inter- and intraobserver variability in group B in comparison to 4B when measuring LV volumes and EF, except for end-systolic volume (ESV) in intraobserver analysis. There were significant differences when calculating the LV volumes (p < 0.001) and EF (p < 0.05) with SB in comparison to 4B in group B.</AbstractText>Single-beat three-dimensional full volume acquisition seems to be superior to four-beat ECG-gated acquisition in measuring left ventricular volumes and ejection fraction in patients having atrial fibrillation. The variability is significantly lower both for ejection fraction and left ventricular volumes.</AbstractText> |
5,206 | [Four-week Levitronix Centrimag bridge-to-transplant for post myocardial infarction cardiogenic shock. A case report]. | Cardiogenic shock after myocardial infarction has a high mortality even if early revascularization is achieved. Biventricular assist devices have not been used in Chile in this critical setting. We report a case of a 55-year-old diabetic man who suffered an acute chest pain and ventricular fibrillation. Prompt outside hospital defibrillation/reanimation restored pulse and allowed emergency room transfer on mechanical ventilation. Electrocardiogram showed an anterior myocardial infarction and early revascularization was achieved by anterior descending artery angioplasty. However, severe cardiogenic shock continued in spite of inotropic and intra aortic balloon pump support. Levitronix Centrimag biventricular mechanical circulatory support was inserted during reanimation for recurrent ventricular fibrillation and the patient listed for urgent cardiac transplantation upon stabilization. Heart transplantation was performed successfully 28 days later and the patient was discharged after a 21-day recovery period. Twelve months after transplant the patient is in NYHA functional class I with normal biventricular function. Levitronix Centrimag biventricular mechanical circulatory support could be used successfully as a bridge-to-transplant for myocardial infarction cardiogenic shock. |
5,207 | Incidence and predictors of subclavian vein obstruction following biventricular device implantation. | The data about the incidence of subclavian venous (SCV) obstruction or thrombosis after biventricular device implantation is limited. Therefore, we aimed to assess the incidence and predictors of venous obstruction after biventricular device implantation with or without a defibrillator in patients with left ventricular systolic dysfunction and cardiac dyssynchrony.</AbstractText>Eighty-six patients who had undergone biventricular device implantation were included in the study. Subclavian vein was patent in 61% of all participants. Among the patients with subclavian obstruction (n = 33), 8 had mild obstruction, 15 had severe obstruction, and 10 had total occlusion. The presence of additional implantable cardioverter defibrillator (ICD) and the number of leads that were used were found to be significant covariates of obstruction in subclavian vein after biventricular device implantation (p = 0.004 and p = 0.01, respectively). Atrial fibrillation after biventricular pacemaker and ICD implantation was significantly related with total occlusion (r = 0.3, p = 0.005 and r = 0.24, p = 0.003, respectively).</AbstractText>Patients who are candidates for biventricular device implantation are at increased risk for venous obstruction when compared with other pacemaker patients and this causes higher incidence of venous obstruction among these patients.</AbstractText> |
5,208 | Pharmacologically induced hypothermia with cannabinoid receptor agonist WIN55, 212-2 after cardiopulmonary resuscitation. | To investigate whether hypothermia could be induced pharmacologically after resuscitation with the cannabinoid CB1/CB2 receptor agonist in a rat model and its effects on outcomes of cardiopulmonary resuscitation.</AbstractText>Prospective, randomized, placebo-controlled experimental study.</AbstractText>University-affiliated animal research laboratory.</AbstractText>Ten healthy male Sprague-Dawley rats.</AbstractText>Ventricular fibrillation was induced and untreated for 6 mins. Defibrillation was attempted after 8 mins of cardiopulmonary resuscitation. Thirty minutes after resuscitation, animals were randomized to receive either WIN55, 212-2 (1.0 mg/kg/hr) or vehicle placebo (1.4 mL/kg/hr) for 6 hrs. Before infusion, the temperature was maintained at 37°C in all the animals with the help of a heating lamp. The same temperature environment was maintained for both groups after infusion.</AbstractText>Hemodynamic measurements and cardiac output, ejection fraction, and myocardial performance index were measured at baseline and hourly for 6 hrs after resuscitation. Survival time up to 72 hrs was observed.</AbstractText>Blood temperature decreased progressively after infusion of WIN55, 212-2 from 37°C to 34°C 4 hrs after resuscitation. There was no significant change in blood temperature after 6 hrs of placebo infusion of the same volume and same infusate temperature. Significantly better postresuscitation myocardial function and longer durations of survival were observed in WIN55, 212-2-treated animals.</AbstractText>The selective cannabinoid agonist, WIN55, 212-2, produced a significant reduction in blood temperature and improved postresuscitation myocardial functions and survival after cardiopulmonary resuscitation. The study results may provide a further option for early and effective induction of therapeutic hypothermia in settings of cardiopulmonary resuscitation.</AbstractText> |
5,209 | Predictors of resuscitation in a swine model of ischemic and nonischemic ventricular fibrillation cardiac arrest: superiority of amplitude spectral area and slope to predict a return of spontaneous circulation when resuscitation efforts are prolonged. | We have demonstrated that a return of spontaneous circulation in the first 3 mins of resuscitation in swine is predicted by ventricular fibrillation waveform (amplitude spectral area or slope) when untreated ventricular fibrillation duration or presence of acute myocardial infarction is unknown. We hypothesized that in prolonged resuscitation efforts that return of spontaneous circulation immediately after a second or later shock with postshock chest compression is independently predicted by end-tidal CO2, coronary perfusion pressure, and ventricular fibrillation waveform measured before that shock in a swine model of ischemic and nonischemic ventricular fibrillation arrest.</AbstractText>Animal intervention study with comparison to a control group.</AbstractText>University animal laboratory.</AbstractText>Twenty swine.</AbstractText>Myocardial infarction was induced by steel plug occlusion of the left anterior descending coronary artery. Ventricular fibrillation was untreated for 8 mins in normal swine (n=10) and acute myocardial infarction swine (n=10).</AbstractText>End-tidal CO2, coronary perfusion pressure, and ventricular fibrillation waveform characteristics of amplitude spectral area and slope were analyzed before second or later shocks. For an amplitude spectral area>35 mV-Hz, the odds ratio for achieving return of spontaneous circulation after that shock was 72 (95% confidence interval, 3.8-1300; p=.004) compared with an amplitude spectral area<28 mV-Hz and with an area under the receiver operator characteristic curve of 0.86. For slope>3.6 mV/s, the odds ratio for achieving return of spontaneous circulation was 36 (95% confidence interval, 2.7-480; p=.007) compared with slope<2.72 mV/s with an area under the curve of 0.86. End-tidal CO2 and coronary perfusion pressure were not predictive of return of spontaneous circulation after a shock, although coronary perfusion pressure was significantly related to both amplitude spectral area (p<.001) and slope (p<.001).</AbstractText>: In prolonged untreated ventricular fibrillation arrest, the waveform characteristics of amplitude spectral area and slope predict the attainment of return of spontaneous circulation with a second or later shock. This has implications for the ideal means to customize the timing of shocks and chest compressions when return of spontaneous circulation is not promptly obtained.</AbstractText> |
5,210 | A patient with commotio cordis successfully resuscitated by bystander cardiopulmonary resuscitation and automated external defibrillator. | Sudden deaths of children and adolescents during competitive sports are usually due to congenital heart diseases. Ventricular fibrillation, however, may also occur in individuals with no underlying cardiac disease who have sustained a low-impact chest wall blow. This phenomenon is described as commotio cordis, and the overall survival rate is poor. Successful resuscitation can be achieved by prompt cardiopulmonary resuscitation and early defibrillation. We report a teenager who sustained a chest wall blow that resulted in a cardiac arrest during a rugby competition. Cardiopulmonary resuscitation was given by bystanders. The ambulance crew arrived with an automated external defibrillator. Ventricular fibrillation was detected and responded to defibrillation. Subsequent investigations including imaging and electrophysiological studies did not reveal any cardiac or brain abnormality, and the patient recovered well neurologically. Accessible cardiopulmonary resuscitation-trained personnel and automated external defibrillators should be present at all organised sporting events. |
5,211 | Moderate exercise prevents impaired Ca2+ handling in heart of CO-exposed rat: implication for sensitivity to ischemia-reperfusion. | Sustained urban carbon monoxide (CO) exposure exacerbates heart vulnerability to ischemia-reperfusion via deleterious effects on the antioxidant status and Ca(2+) homeostasis of cardiomyocytes. The aim of this work was to evaluate whether moderate exercise training prevents these effects. Wistar rats were randomly assigned to a control group and to CO groups, living during 4 wk in simulated urban CO pollution (30-100 parts/million, 12 h/day) with (CO-Ex) or sedentary without exercise (CO-Sed). The exercise procedure began 4 wk before CO exposure and was maintained twice a week in standard filtered air during CO exposure. On one set of rats, myocardial ischemia (30 min) and reperfusion (120 min) were performed on isolated perfused rat hearts. On another set of rats, myocardial antioxidant status and Ca(2+) handling were evaluated following environmental exposure. As a result, exercise training prevented CO-induced myocardial phenotypical changes. Indeed, exercise induced myocardial antioxidant status recovery in CO-exposed rats, which is accompanied by a normalization of sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a expression and then of Ca(2+) handling. Importantly, in CO-exposed rats, the normalization of cardiomyocyte phenotype with moderate exercise was associated with a restored sensitivity of the myocardium to ischemia-reperfusion. Indeed, CO-Ex rats presented a lower infarct size and a significant decrease of reperfusion arrhythmias compared with their sedentary counterparts. To conclude, moderate exercise, by preventing CO-induced Ca(2+) handling and myocardial antioxidant status alterations, reduces heart vulnerability to ischemia-reperfusion. |
5,212 | Left atrial volume index as a predictor for occurrence of atrial fibrillation after ablation of typical atrial flutter. | Radiofrequency catheter ablation of the cavotricuspid isthmus (CTI) is effective in the treatment of typical atrial flutter (AFL) and atrial fibrillation (AF). AF and AFL often coexist. However, AF often occurs following successful ablation of CTI. The aim of this study was to investigate the predictors of concomitant AF following successful ablation of AFL.</AbstractText>We enrolled 122 patients [59.1 ± 11.3 years, male 100 (82.0%)] with typical AFL, who received successful ablation of the CTI. They were followed up at outpatient clinic (24.6 ± 25.7 months). Twelve-lead electrocardiogram and Holter monitoring were used to confirm the diagnosis of recurrent AFL or AF. We assessed prior history of AF, structural heart disease, left ventricular ejection fraction, left atrial diameter (LAD), left atrial volume index (LAVI), and AFL cycle length.</AbstractText>Among the 122 ablated patients, 15 (12.3%) had recurrent AFL and 33 (27.0%) had recurrent AF. In univariate logistic analysis, LAD and LAVI could significantly predict the recurrence of AF after AFL ablation. However, multivariate logistic regression analysis found that the independent predictor of recurrent AF was LAVI. An LAVI of 42.6 mL may allow for the differentiation between only AFL and AFL with concomitant AF with 69.0% sensitivity and 69.8% specificity.</AbstractText>LAVI might be a useful predictor for occurrence of AF after ablation of typical AFL.</AbstractText>Copyright © 2010. Published by Elsevier Ltd.</CopyrightInformation> |
5,213 | Clinical, electrocardiographic, and electrophysiologic characteristics of patients with a fasciculoventricular pathway: the role of PRKAG2 mutation. | The ECG, clinical, and electrophysiologic profiles of patients with a fasciculoventricular pathway are well described. Fasciculoventricular pathways occurring in the setting of glycogen storage cardiomyopathy possess unique features.</AbstractText>The purpose of this study was to compare the clinical, ECG, and electrophysiologic characteristics of patients with a fasciculoventricular pathway, with or without glycogen storage cardiomyopathy.</AbstractText>Two groups of patients with a fasciculoventricular pathway were compared: group A consisted of 10 patients with the PRKAG2 mutation (Arg302gln), and group B consisted of 9 patients without the mutation.</AbstractText>Thirty percent of group A patients had left ventricular hypertrophy, and none had an additional accessory pathway. Group B patients had no structural heart disease, and 33% had an additional accessory pathway. Group A patients had a slower resting heart rate (56 ± 7 vs 75 ± 10 bpm, P <0.0001), a wider QRS complex (0.15 ± 0.01 vs 0.11 ± 0.02 ms, P = .0004), and a longer HV interval (34 ± 1 vs 25 ± 3 ms, P = .0003). During long-term follow-up, 50% of group A patients developed complete AV block versus none in group B. Eighty percent of group A patients developed atrial flutter and/or atrial fibrillation. No Group B patient had any arrhythmia during follow-up after successful ablation of additional arrhythmia circuits. No sustained ventricular arrhythmia was induced in any patient from either group.</AbstractText>Patients with a fasciculoventricular pathway associated with the PRKAG2 mutation have distinct clinical, ECG, and electrophysiologic profiles and should be correctly identified because of their ominous long-term prognosis. Patients without the mutation have an excellent arrhythmia-free prognosis after treatment of additional circuits.</AbstractText>Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,214 | An ECG index of myocardial scar enhances prediction of defibrillator shocks: an analysis of the Sudden Cardiac Death in Heart Failure Trial. | Only a minority of patients receiving implantable cardioverter-defibrillators (ICDs) for the primary prevention of sudden death receive appropriate shocks, yet almost as many are subjected to inappropriate shocks and device complications. Identifying and quantifying myocardial scar, which forms the substrate for ventricular tachyarrhythmias, may improve risk stratification.</AbstractText>This study sought to determine whether the absence of myocardial scar detected by novel 12-lead electrocardiographic (ECG) Selvester QRS scoring criteria identifies patients with low risk for appropriate ICD shocks.</AbstractText>We applied QRS scoring to 797 patients from the ICD arm of the Sudden Cardiac Death in Heart Failure Trial. Patients were followed up for a median of 45.5 months for ventricular tachycardia/fibrillation treated by the ICD or sudden tachyarrhythmic death (combined group referred to as VT/VF).</AbstractText>Increasing QRS score scar size predicted higher rates of VT/VF. Patients with no scar (QRS score = 0) represented a particularly low-risk cohort with 48% fewer VT/VF events than the rest of the population (absolute difference 11%; hazard ratio 0.52, 95% confidence interval 0.31 to 0.88). QRS score scar absence versus presence remained a significant prognostic factor after controlling for 10 clinically relevant variables. Combining QRS score (scar absence versus presence) with ejection fraction (≥ 25% versus < 25%) distinguished low-, middle-, and high-risk subgroups with 73% fewer VT/VF events in the low-risk versus high-risk group (absolute difference 22%; hazard ratio = 0.27, 95% confidence interval 0.12 to 0.62).</AbstractText>Patients with no scar by QRS scoring have significantly fewer VT/VF events. This inexpensive 12-lead ECG tool provides unique, incremental prognostic information and should be considered in risk-stratifying algorithms for selecting patients for ICDs.</AbstractText>Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,215 | Left-ventricular electromechanical delay is prolonged in patients with postoperative atrial fibrillation. | Although several risk factors for postoperative atrial fibrillation (AF) have been proposed, it remains the most common complication after cardiac surgery, even in low-risk patients. There is still no single reliable and reproducible parameter for predicting AF, and no standardized recommendation exists for this issue. Electromechanical delay (excitation-contraction coupling delay) is the time delay from the electrical activation to the actual systolic motion, and it reflects abnormality in calcium-handling proteins, which is considered one mechanism of postoperative AF. We hypothesized that left-ventricular electromechanical delay (LVEMD) is correlated to postoperative AF and serially examined it by echocardiography.</AbstractText>We prospectively included 16 patients with relatively low risk for AF, who underwent cardiac surgery. The inclusion criteria were younger than 80 years, an ejection fraction greater than 45%, a left-atrial dimension less than 50mm, and a brain natriuretic peptide (BNP) value less than 250 pg ml⁻¹. Postoperative AF for 10 postoperative days was monitored by 24-h electrocardiogram. The LVEMD was assessed by pulse-wave tissue Doppler echocardiography before and 1, 3, and 7 days after the operation. Serum BNP, adrenalin, and noradrenalin levels were also examined at the same time.</AbstractText>Postoperative AF was detected in six (37.5%) patients. There was no significant difference in heart rate, QRS duration, and serum hormones between the non-AF (n = 10) and AF (n = 6) groups. Although the preoperative LVEMD was comparable, that on postoperative day 1 of the AF group was significantly longer than that of the non-AF group (in the septal wall, 174 ± 50 vs 101 ± 36 ms, p = 0.020; in the lateral wall, 195 ± 71 and 111 ± 37 ms, p = 0.029). A LVEMD on postoperative day 1 greater than 150 ms well predicted postoperative AF (sensitivity, 75% and 75%; specificity, 100% and 86%, in septal and lateral LVEMDs, respectively).</AbstractText>LVEMD is prolonged in patients with postoperative AF. This could be a new predicting parameter for AF in low-risk patients.</AbstractText>Copyright © 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.</CopyrightInformation> |
5,216 | Synergistic effect of the combination of ranolazine and dronedarone to suppress atrial fibrillation. | The aim of this study was to evaluate the effectiveness of a combination of dronedarone and ranolazine in suppression of atrial fibrillation (AF).</AbstractText>Safe and effective pharmacological management of AF remains one of the greatest unmet medical needs.</AbstractText>The electrophysiological effects of dronedarone (10 μmol/l) and a relatively low concentration of ranolazine (5 μmol/l) separately and in combination were evaluated in canine isolated coronary-perfused right and left atrial and left ventricular preparations as well as in pulmonary vein preparations.</AbstractText>Ranolazine caused moderate atrial-selective prolongation of action potential duration and atrial-selective depression of sodium channel-mediated parameters, including maximal rate of rise of the action potential upstroke, leading to the development of atrial-specific post-repolarization refractoriness. Dronedarone caused little or no change in electrophysiological parameters in both atrial and ventricular preparations. The combination of dronedarone and ranolazine caused little change in action potential duration in either chamber but induced potent use-dependent atrial-selective depression of the sodium channel-mediated parameters (maximal rate of rise of the action potential upstroke, diastolic threshold of excitation, and the shortest cycle length permitting a 1:1 response) and considerable post-repolarization refractoriness. Separately, dronedarone or a low concentration of ranolazine prevented the induction of AF in 17% and 29% of preparations, respectively. In combination, the 2 drugs suppressed AF and triggered activity and prevented the induction of AF in 9 of 10 preparations (90%).</AbstractText>Low concentrations of ranolazine and dronedarone produce relatively weak electrophysiological effects and weak suppression of AF when used separately but when combined exert potent synergistic effects, resulting in atrial-selective depression of sodium channel-dependent parameters and effective suppression of AF.</AbstractText>Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,217 | Clinical and mechanistic issues in early repolarization of normal variants and lethal arrhythmia syndromes. | Early repolarization, involving ST-segment elevation and, sometimes, prominent J waves at the QRS-ST junction, has been considered a normal electrocardiographic variant for over 60 years. A growing number of case reports and case-control studies indicate that in some instances, early repolarization patterns are associated with increased risk of idiopathic ventricular fibrillation. Epidemiological evidence indicates a dose effect for the risk of cardiac and sudden death with the extent of J-point elevation. This paper reviews present knowledge regarding the epidemiology, presentation, therapeutic response, and mechanisms characteristic of early repolarization. We highlight major unanswered questions relating to our limited ability to determine which individuals with this common electrocardiographic variant are at risk for sudden death, our incomplete understanding of underlying mechanisms, the inadequate information regarding genetic determinants and therapeutic responses, and the unclear relationship between early repolarization and other conditions involving accelerated repolarization and sudden arrhythmic death such as Brugada and short-QT syndromes. This review paper intends to inform the practicing physician about important clinical issues and to stimulate investigators to address the many unresolved questions in this rapidly evolving field. |
5,218 | Ranolazine safely decreases ventricular and atrial fibrillation in Timothy syndrome (LQT8). | Long QT eight (LQT8), otherwise known as Timothy syndrome (TS), is a genetic disorder causing hyper-activation of the L-type calcium channel Cav 1.2. This calcium load and the resultant increase in the QT interval provide the substrate for ventricular arrhythmias. We previously presented a case in a patient with TS who had a profound decrease in his burden of ventricular arrhythmias after institution of an L-type calcium channel blocker. Although this patient's arrhythmia burden had decreased, he displayed an increasing burden of atrial fibrillation and still had bouts of ventricular fibrillation requiring defibrillator therapy. Basic research has recently shown that ranolazine, a multipotent ion-channel blocker, may be of benefit in patients with LQT8 syndrome. This case report details the decrease of atrial fibrillation and ventricular fibrillation events in our LQT8 patient with the addition of ranolazine. |
5,219 | A novel echocardiographic marker in hypertensive patients: is diastolic dysfunction associated with atrial electromechanical abnormalities in hypertension? | Atrial arrhythmias are common problems in hypertensive patients. Atrial electromechanical delay (AEMD) can be used to evaluate development of atrial arrhythmias. The authors aimed to assess inter- and intra-AEMD in hypertensive patients. The study population consisted of 200 medically treated hypertensive patients and 151 normotensive controls. Inter-AEMD and intra-left AEMD were measured from parameters of Doppler tissue imaging. There were 72 (36%) hypertensive patients with diastolic dysfunction, 128 (64%) patients without diastolic dysfunction, and 151 healthy controls. Inter-AEMD (59 ms [36-104 ms] vs 42 ms [36-68 ms] vs 46 ms [30-82 ms]) was significantly higher in hypertensive patients with diastolic dysfunction compared with patients without diastolic dysfunction and controls. Our data demonstrated that inter-AEMD is longer in hypertensive patients with diastolic dysfunction. It may be suggested that diastolic dysfunction is associated with atrial electromechanical abnormalities, which can be associated with atrial fibrillation in hypertension. |
5,220 | Pulmonary Vein Sleeves as a Pharmacologic Model for the Study of Atrial Fibrillation. | To review the electrophysiologic effects of antiarrhythmic agents in pulmonary veins (PV) sleeve preparations.</AbstractText>Ectopic activity arising from the PV plays a prominent role in the development of atrial fibrillation.</AbstractText>Transmembrane action potentials were recorded from canine superfused left superior or inferior PV sleeves using standard microelectrode techniques. Acetylcholine (ACh, 1 μM), isoproterenol (1 μM), high calcium ([Ca2+]o=5.4mM) or a combination was used to induce early or delayed afterdepolarizations (EADs or DADs) and triggered activity.</AbstractText>In canine PV sleeves, ranolazine (10 μM) induced a marked use-dependent decrease in Vmax, a rate-dependent abbreviation of action potential duration (APD), but a rate-dependent increase in effective refractory period due to the development of post-repolarization refractoriness and eliminates rate-dependent delayed and late phase 3 early afterdepolarizations (DADs and EADs)-induced triggered activity induced by high calcium, isoproterenol, acetylcholine of their combination together with rapid pacing. Chronic amiodarone induced a prolongation of APD, a marked decrease in Vmax, and prevented the development of DADs and late phase 3 EADs-induced triggered activity. Combination of ranolazine and chronic amiodarone act synergistically to cause potent use-dependent depression of sodium channel-dependent parameters in PV sleeves but not ventricular tissues.</AbstractText>The PV sleeve preparation is a useful model for the study of pharmacologic agents for the treatment of atrial fibrillation. The effectiveness of these agents in arrhythmias induced in PV sleeves may indicate an antiarrhythmic action in eliminating the triggers responsible for AF.</AbstractText> |
5,221 | MRI-Guided Electrophysiology Intervention. | Catheter ablation is a first-line treatment for many cardiac arrhythmias and is generally performed under X-ray fluoroscopy guidance. However, current techniques for ablating complex arrhythmias such as atrial fibrillation and ventricular tachycardia are associated with sub-optimal success rates and prolonged radiation exposure. Pre-procedure 3-D magnetic resonance imaging (MRI) has improved understanding of the anatomic basis of complex arrhythmias and is being used for planning and guidance of ablation procedures. A particular strength of MRI compared to other imaging modalities is the ability to visualize ablation lesions. Post-procedure MRI is now being applied to assess ablation lesion location and permanence with the goal of identifying factors leading to procedure success and failure. In the future, intra-procedure real-time MRI, together with the ability to image complex 3-D arrhythmogenic anatomy and target additional ablation to regions of incomplete lesion formation, may allow for more successful treatment of even complex arrhythmias without exposure to ionizing radiation. Development of clinical grade MRI-compatible electrophysiology devices is required to transition intra-procedure MRI from preclinical studies to more routine use in patients. |
5,222 | Cardiac arrhythmias and left ventricular hypertrophy in systemic hypertension. | Hypertensive left ventricular hypertrophy (LVH) is associated with increased risk of arrhythmias and mortality. Objective was to investigate the prevalence of cardiac arrhythmias and LVH in systemic hypertension.</AbstractText>In all subjects blood pressure was measured, electrocardiography and echocardiography was done. Holter monitoring and exercise test perform in certain cases. There were 500 hypertensive patients, 156 (31.2%) men and 344 (69%) women > 30 years of age in the study. Among them 177 (35.4%) were diabetic, 224 (45%) were dyslipidemia, 188 (37.6%) were smokers, and 14 (3%) had homocysteinemia. Duration of hypertension (HTN) was > or = 2 years). Mean systolic BP (SBP) was 180 +/- 20 mm Hg and diastolic BP (DBP) was 95 +/- 12 in male and female patients. Left ventricular mass index (LVMI) was 119.2 +/- 30 gm/m2 in male while 103 +/- 22 gm/m2 in female patients. Palpitation was seen in 126 (25%) male and 299 (59.8%) female patients. Atrial fibrillation was noted in 108 (21.6%) male and 125 (25%) female patients, 30 (6%) male and 82 (16.4%) female patients had atrial flutter. Ventricular tachycardia was noted in 37 (7.4%) male and 59 (11.8%) female patients. Holter monitoring showed significant premature ventricular contractions (PVC'S) in 109 (21.8%) male and 128 (25.69%) female patients while Holter showed atrial arrhythmias (APC'S) in 89 (17.8%) males and 119 (23.8%) females. Angiography findings diagnosed coronary artery disease in 119 (23.8%) with CAD male and 225 (45%) without CAD while 47 (9.4%) females presented with CAD and 109 (21.8%) without CAD.</AbstractText>A significant association has been demonstrated between hypertension and arrhythmias. Diastolic dysfunction of the left ventricle, left atrial size and function, as well as LVH have been suggested as the underlying risk factors for supraventricular, ventricular arrhythmias and sudden death in hypertensives with LVH.</AbstractText> |
5,223 | Incidence of, predictors for, and mortality associated with malignant ventricular arrhythmias in non-ST elevation myocardial infarction patients. | The incidence of non-ST elevation myocardial infarction (NSTEMI) is increasing. Although life-threatening ventricular arrhythmias have been well-documented in patients with ST elevation MI (STEMI), their incidence and importance in NSTEMI have not been examined in similar detail. We examined the incidence, predictors, and mortality rates of ventricular arrhythmias in a cohort of NSTEMI patients undergoing an early invasive strategy.</AbstractText>Consecutive patients admitted with NSTEMI who underwent cardiac catheterization within 48 h of admission were identified by chart review. Presence and type of ventricular arrhythmias and 30-day mortality were recorded. Malignant arrhythmias were defined as sustained ventricular tachycardia (VT, >100 beats/min lasting >30 s) or fibrillation (VF). Clinical risk factors, laboratory values, findings on electrocardiogram, echocardiogram, cardiac catheterization, and revascularization procedure data were recorded.</AbstractText>VT/VF occurred in 21 (7.6%) of 277 NSTEMI patients. Sixty percent of these events occurred within the first 48 h after hospital admission, with a median occurrence at 72 h. Twelve patients (4.3%) required defibrillation. Troponin levels were higher and left ventricular ejection fraction was lower in the VT/VF group. Multivariable analysis also identified the presence of left bundle branch block and need for urgent coronary artery bypass grafting as significant predictors of malignant ventricular arrhythmias. Thirty-day mortality was significantly higher in NSTEMI patients with malignant ventricular arrhythmias than without (38 vs. 3%, P<0.001).</AbstractText>Despite an early invasive strategy, malignant ventricular arrhythmias are frequent in NSTEMI patients and are associated with increased 30-day mortality.</AbstractText> |
5,224 | Brugada syndrome with aborted sudden cardiac death related to liquorice-induced hypokalemia. | It was the aim of this study to report an aborted cardiac arrest due to ventricular fibrillation and electrocardiographic changes consistent with Brugada syndrome due to liquorice-induced hypokalemia.</AbstractText>Ventricular fibrillation was witnessed in a 50-year-old woman who was admitted to our emergency department with a history of liquorice ingestion, a herbal product. After stopping liquorice ingestion, the Brugada-like electrocardiographic pattern changed progressively with potassium replacement. A diagnosis of Brugada syndrome was made after the ajmaline challenge test. The patient was discharged with an implantable cardioverter defibrillator and had an uneventful follow-up.</AbstractText>This report illustrates the importance of the investigation for herbal medications in the detailed history of a patient in the cases of electrolyte disturbances and the potential role of hypokalemia in the induction of malignant arrhythmia in Brugada syndrome.</AbstractText>Copyright © 2010 S. Karger AG, Basel.</CopyrightInformation> |
5,225 | Homocysteine levels in patients with heart failure with preserved ejection fraction. | Increased homocysteine (HCY) levels are associated with an increased risk of cardiovascular disease. Plasma HCY is increased in chronic heart failure (CHF) patients, and previous studies suggest that hyperhomocysteinemia causes adverse cardiac remodeling and affects pump function. We aimed to evaluate the HCY levels in patients with diastolic heart failure with preserved left ventricular ejection fraction (LVEF).</AbstractText>We prospectively studied 68 patients (39 females and 29 males) who were hospitalized for symptomatic heart failure, as well as 40 age- and sex-matched healthy subjects who comprised the control group. CHF was diagnosed in all cases based on Framingham diagnostic criteria. CHF with preserved LVEF was defined as cases with CHF with an LVEF of 50% or more. Patients with regional left ventricular wall motion abnormalities, atrial fibrillation, and renal failure were excluded.</AbstractText>The mean age was 65.5 ± 9.6 years in the heart failure group and 65.2 ± 9.7 years in the control group. The mean LVEF was 59.8 ± 5.3 in the heart failure group and 61.4 ± 5.2 in the control group. The mean total fasting HCY concentrations were significantly higher in patients with heart failure (16.9 ± 5.27 μmol/l vs. 10.15 ± 3.49 μmol/l, respectively; p < 0.001). Multiple regression analysis indicated that NT-proBNP, hs-CRP, E/A ratio, and HbA1C were independently associated with hyperhomocysteinemia.</AbstractText>Our results suggest that hyperhomocysteinemia is prevalent in heart failure with preserved ejection fraction. Larger scale studies are needed to clarify its pathogenic mechanisms and effects on the natural history of heart failure.</AbstractText>Copyright © 2010 S. Karger AG, Basel.</CopyrightInformation> |
5,226 | Decreased apoptosis following successful ablation of atrial fibrillation. | Increased apoptotic processes in tissue samples from hearts in atrial fibrillation (AF) have been previously documented in animals. Whether the restoration of sinus rhythm is associated with decreased apoptosis is not known. The aim of the present study was to establish whether successful epicardial ablation of AF leads to changes in the concentration of serum markers of apoptosis.</AbstractText>Twenty-five patients with AF were prospectively studied. All underwent epicardial isolation of pulmonary veins. The success of the ablation was assessed clinically and with 3 Holter recordings. Blood samples were drawn before surgery, and at 3 and 6 months after. Serum concentrations of Fas (apoptosis-stimulating fragment) and TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) were measured using ELISA.</AbstractText>AF was successfully ablated in 15 patients (SR group). In the other 10 patients (AF group), AF recurred during follow-up. Neither group differed with respect to age, sex, left ventricular ejection fraction, or preoperative concentrations of measured molecules. While Fas decreased in successfully ablated patients, there was no change in the Fas concentration in the AF group. Similarly, the concentrations of TRAIL decreased in the SR group, but remained unchanged in the AF group.</AbstractText>The ablation of AF is associated with decreased serum markers for apoptosis.</AbstractText>Copyright © 2010 S. Karger AG, Basel.</CopyrightInformation> |
5,227 | Heart rate-dependent variability of cardiac events in type 2 congenital long-QT syndrome. | We aimed to examine the validity of heart rate (HR) at rest before β-blocker therapy as a risk factor influencing cardiac events (ventricular fibrillation, torsades de pointes, or syncope) in long QT type 2 (LQT2) patients.</AbstractText>In 110 genetically confirmed LQT2 patients (45 probands), we examined the significance of variables [HR at rest, corrected QT (QTc), female gender, age of the first cardiac event, mutation site] as a risk factor for cardiac events. We also evaluated frequency of cardiac events in four groups classified by the combination of basal HR and QTc with cutoff values of 60 b.p.m. and 500 ms to estimate if these two electrocardiographic parameters in combination could be a good predictor of outcome (mean follow-up period: 50 ± 39 months). Logistic regression analysis revealed three predictors: HR < 60 b.p.m., QTc ≥ 500 ms, and female gender. When the study population was divided into four groups using the cutoff values of 60 b.p.m. for HR and 500 ms for QTc, the cumulative event-free survival by the Kaplan-Meier method was significantly higher in the group with HR ≥ 60 b.p.m. and QTc < 500 ms than in the group with HR < 60 b.p.m. and QTc < 500 ms or that with HR < 60 b.p.m. and QTc ≥ 500 m (P < 0.05). Irrespective of QTc interval, LQT2 patients with basal HR < 60 b.p.m. were at significantly higher risk.</AbstractText>The basal HR of < 60 b.p.m. is a notable risk factor for the prediction of life-threatening arrhythmias in LQT2 patients.</AbstractText> |
5,228 | Characteristics and clinical outcome of 458 patients with acute myocardial infarction requiring mechanical ventilation. Results of the BEAT registry of the ALKK-study group. | Information about the clinical course of patients with acute myocardial infarction requiring mechanical ventilation is scarce. We sought to evaluate the clinical outcome of a large cohort of such patients in clinical practice.</AbstractText>The German BEAT registry prospectively enrolled consecutive patients requiring mechanical ventilation who were admitted to an internal intensive care unit (ICU) of 45 participating German hospitals between September 2001 and June 2002. For this analysis, we created a subgroup of patients with acute ST-segment-elevation or non-ST-segment-elevation myocardial infarction.</AbstractText>During the 9-month study period, 458 consecutive patients fulfilled our inclusion criteria. The mean age was 68 ± 8 years and 71% were men. 40% of the patients were already intubated in the prehospital phase. The initial reason for intubation was in 48% of the cases ventricular fibrillation/tachycardia or sudden cardiac death, in 39% congestive heart failure and in 13% of the cases non-cardiac. The median time of ventilation was 2 days (1-5) among survivors and 1 day (0-5) among non-survivors. Of the 458 patients, 256 (56%) had already or developed cardiogenic shock, 86 (19%) acute renal failure, 76 (17%) coma or brain damage, 64 (14%) severe infection, 46 (10%) sepsis and 28 (6%) multiorgan distress syndrome; 11% were treated with fibrinolysis, 39% with PCI and 6% with coronary artery bypass grafting. The overall hospital mortality rate was 48%. In patients with cardiogenic shock, mortality was even higher with 69%.</AbstractText>Patients requiring mechanical ventilation during an acute myocardial infarction constitute a high risk group with a mortality of about 50%. Further research is necessary to improve the outcome of these patients.</AbstractText> |
5,229 | Report from J-PULSE multicenter registry of patients with shock-resistant out-of-hospital cardiac arrest treated with nifekalant hydrochloride. | Nifekalant hydrochloride (NIF) is an intravenous class-III antiarrhythmic agent that purely blocks the K(+)-channel without inhibiting β-adrenergic receptors. The present study was designed to investigate the feasibility of NIF as a life-saving therapy for out-of-hospital ventricular fibrillation (VF).</AbstractText>The Japanese Population-based Utstein-style study with basic and advanced Life Support Education study was a multi-center registry study with 4 participating institutes located at the northern urban area of Osaka, Japan. Eligible patients were those treated with NIF because of out-of-hospital VF refractory to 3 or more precordial shocks and intravenous epinephrine. Between February 2006 and February 2007, 17 patients were enrolled for the study. The time from a call for emergency medical service to the first shock was 12(6-26)min. The time from the first shock to the NIF administration was 25.5(9-264)min and the usage dose of NIF was 25(15-210)mg. When excluding 3 patients in whom percutaneous extracorporeal membrane oxygenation was applied before NIF administration, the rate of return of spontaneous circulation was 86% and the rate of admission alive to the hospital was 79%. One patient developed torsade de pointes.</AbstractText>Intravenous administration of NIF seems to be feasible as a potential therapy for advanced cardiac life-support in patients with out-of-hospital VF, and therefore further study is warranted.</AbstractText> |
5,230 | Numerically simulated cardiac exposure to electric current densities induced by TASER X-26 pulses in adult men. | There is still an ongoing debate whether or not electronic stun devices (ESDs) induce cardiac fibrillation. To assess the ventricular fibrillation risk of law enforcing electronic control devices, quantitative estimates of cardiac electric current densities induced by delivered electric pulses are essential. Numerical simulations were performed with the finite integration technique and the anatomical model of a standardized European man (NORMAN) segmented into 2 mm voxels and 35 different tissues. The load-dependent delivery of TASER X-26 pulses has been taken into account. Cardiac exposure to electric current densities of vertically and horizontally aligned dart electrodes was quantified and different hit scenarios compared. Since fibrillation thresholds critically depend on exposed volume, the provided quantitative data are essential for risk assessment. The maximum cardiac rms current densities amounted to 7730 A m(-2). Such high current densities and exposed cardiac volumes do not exclude ventricular fibrillation. |
5,231 | Downloadable software algorithm reduces inappropriate shocks caused by implantable cardioverter-defibrillator lead fractures: a prospective study. | Downloadable software upgrades are common in consumer electronics but not in implantable medical devices. Fractures of implantable cardioverter-defibrillator (ICD) leads present commonly as inappropriate shocks. A lead-integrity alert (LIA) designed to reduce inappropriate shocks is the first software download approved to enhance nominally functioning, previously implanted ICDs.</AbstractText>We performed a prospective study to determine whether an LIA could reduce inappropriate shocks. Patients were included if they had ICD lead fractures confirmed by analysis of explanted leads. The LIA group included the first 213 patients who met the inclusion criteria after the LIA was approved who had the LIA downloaded. The LIA is triggered either by high impedance or rapid oversensing. It responds by delaying detection of ventricular fibrillation and initiating a patient alert every 4 hours. The control group included the first 213 patients who did not have the LIA downloaded. They were monitored by conventional daily impedance measurements that respond with a daily alert. The LIA group had a 46% relative reduction (95% confidence interval 34% to 55%) in the percentage of patients with ≥1 inappropriate shock (LIA 38% versus control 70%, P<0.001) and a 50% relative reduction (95% confidence interval 33% to 61%) in the percentage with ≥5 shocks (25% versus 50%, P<0.001). The LIA group also had a higher percentage of patients who either did not receive a shock or had ≥3 days of warning before the shock (72% versus 50%, P<0.001).</AbstractText>A software download that upgrades previously implanted ICDs without surgical revision reduces inappropriate shocks caused by lead fractures.</AbstractText> |
5,232 | Molecular determinants of human ether-à-go-go-related gene 1 (hERG1) K+ channel activation by NS1643. | Human ether-à-go-go-related gene 1 (hERG1) channels conduct the rapid delayed rectifier K+ current, I(Kr), an important determinant of action potential repolarization in mammals, including humans. Reduced I(Kr) function caused by mutations in KCNH2 or drug block of hERG1 channels prolongs the QT interval of the electrocardiogram and increases the risk of ventricular fibrillation and sudden cardiac death. Several activators of hERG1 channels have been discovered in recent years. These compounds shorten the duration of cardiac action potentials and have been proposed as a new therapeutic approach for the treatment of acquired or congenital long QT syndrome. We defined previously the mechanism of action of 1,3-bis-(2-hydroxy-5-trifluoromethyl-phenyl)-urea (NS1643), a compound that increases hERG1 currents by shifting the voltage-dependence of inactivation to more positive potentials. Here, we use scanning mutagenesis of hERG1 and functional characterization of 56 mutant channels heterologously expressed in Xenopus laevis oocytes to define the molecular determinants of the binding site for NS1643. Most point mutations did not alter response to the drug; however, 10 mutant channels had reduced sensitivity, and F619A and I567A exhibited enhanced activation by the drug. Some of these residues form a cluster and, together with molecular modeling, suggest that NS1643 binds to a pocket near the extracellular ends of the S5/S6 segments of two adjacent hERG1 channel subunits. This putative binding site differs from the sites described previously for two other hERG1 activators, (3R,4R)-4-[3-(6-methoxy-quinolin-4-yl)-3-oxo-propyl]-1-[3-(2,3,5-trifluoro-phenyl)-prop-2-ynyl]-piperidine-3-carboxylic acid (RPR260243) and 2-(4-[2-(3,4-dichloro-phenyl)-ethyl]-phenylamino)-benzoic acid (PD-118057). |
5,233 | Cavotricuspid isthmus dependent flutter is associated with an increased incidence of occult coronary artery disease. | Atrial flutter (AFl) and atrial fibrillation (AFib) share many clinical risk factors and potential mechanisms with atherosclerosis. Despite this, an association between stable coronary artery disease (CAD) and atrial arrhythmias has not previously been documented. To investigate this hypothesis we measured the incidence of occult coronary atheroma on coronary angiography inpatients undergoing radiofrequency ablation procedures.</AbstractText>Consecutive coronary angiograms performed on patients with no history or symptoms of CAD undergoing elective ablation of arrhythmias were analysed. Patients were divided into three groups according to their arrhythmia: Typical right AFl, AFib, and a matched control group undergoing ablation for either atrioventricular node-dependent supraventricular tachycardia (SVT) or idiopathic right ventricular outflow tract tachycardia (RVOT). Atherosclerosis on angiography was graded according to the most severe stenosis. A total of 138 patients were included. Groups were evenly matched for age (P = 0.4), risk factors for coronary disease including hypertension (P = 0.38) and diabetes (P = 0.2). The incidence of asymptomatic, occult coronary atheroma was significantly greater in patients with AFl (AFl 54%, AFib 26%, SVT/RVOT 21%, P = 0.005). In contrast there was no higher incidence of occult atheroma in patients with AFib than those with SVT/RVOT (P = 0.68). The majority of atherosclerosis observed was mild, non-obstructive plaque disease (AFl 75%, AFib 44%, SVT/RVOT 67%).</AbstractText>There was a significantly greater incidence of occult coronary atheroma in asymptomatic patients undergoing ablation for AFl, suggesting that the mechanism underlying the development of atherosclerosis may also be important in creating the substrate that allows typical right AFl to develop.</AbstractText> |
5,234 | Endocardial vagal atrioventricular node stimulation in humans: reproducibility on 18-month follow-up. | Control of atrioventricular (AV) node conduction by means of high-frequency stimulation (HFS) of efferent AV node vagal stimulation (AVNS) fibres enables the ventricular rate (VR) to be modulated during atrial fibrillation (AF). The aims of this study were to verify, on 18-month follow-up, the reproducibility of the dromotropic effect obtained on implantation and the long-term reliability of the system in patients who received an implantable cardioverter-defibrillator (ICD) with a standard atrial lead positioned at a location suitable for AVNS.</AbstractText>We enrolled 12 patients with paroxysmal or persistent AF who were candidates for ICD. The right atrium was mapped to locate the pacing site, and a transvenous screw-in lead was implanted in that region. The voltages required for VR modulation (25% VR reduction) and complete AV block at different pulse durations (from 0.1 to 0.5 ms) were recorded. Eleven out of 12 patients underwent 18-month follow-up examination. Atrial pacing parameters were adequate and did not differ from the baseline values (all P > 0.05): pacing threshold 0.9 ± 0.5 V (0.5 ms pulse duration) and impedance 556 ± 121 Ω, with P-wave amplitude of 1.6 ± 0.7 mV. High-frequency stimulation induced VR modulation in nine patients and complete AV block in eight patients at pulse durations ≥0.3 ms. No differences were observed in the voltages for VR modulation and complete AV block between implantation and 18-month examination (all P > 0.100).</AbstractText>Ventricular rate control during AF was obtained under HFS 18 months after implantation in patients with the atrial lead positioned at a location suitable for AVNS. The pacing outputs needed to achieve the dromotropic effect were comparable to those measured on implantation.</AbstractText> |
5,235 | Therapeutic medical hypothermia--a multispecialty approach. | Cardiac arrest remains one of the most common causes of death in developed countries. Those who survive may have significant neurologic morbidity. In the current decade, therapeutic medical hypothermia (TMH) has emerged as the only treatment that unequivocally improves neurologic outcomes in post ventricular fibrillation / ventricular tachycardia induced cardiac arrest. The role of TMH in other forms of cardiac arrest continues to evolve. We present the current status of medical hypothermia, recent patents and recent advances of this evolving therapy. |
5,236 | Effects of tirofiban and percutaneous coronary intervention in an old patient with acute myocardial infarction and cardiogenic shock. | A 75 year old man presented in our institutition with acute inferoposterior and right ventricular ST-segment elevation myocardial infarction and cardiogenic shock, 40 minutes after the pain onset. He was pretreated with 300 mg of aspirin, 600 mg of clopidogrel, and was taken to the catheterization laboratory. Door to needle time was 35 minutes. Primary percutaneous coronary intervention with bare-metal stent implantation first in infarct related right coronary artery, with subsequent high-bolus dose (25 microg/kg) tirofiban, and then in suboccluded RCx were done. The procedures were done during the cardio-pulmo-cerebral reanimation because of relapsing ventricular fibrillation, with final TIMI 3 coronary flow established. Subsequently, intraaortic balloon pump was inserted Echocardiography taken on the second day showed globaly hypokinetic left ventricle, with 10% ejection fraction and competent valves. During the next three weeks of hospital follow-up, there were no major adverse cardiac events, a transient azotemia and fall in hemoglobin concentration without major bleeding, and no episodes of severe thrombocytopenia were recorded. After six months, the patient was without chest pains, 2/3 class according to the New York Heart Association, without major adverse events, and echocardiographic left ventricular ejection fraction increment for 30%. |
5,237 | Clinical observation on the treatment of atrial fibrillation with amiodarone combined with Shenmai Injection (参麦注射液). | To observe the therapeutic efficacy and safety of amiodarone combined with Shenmai Injection (参麦注射液) on atrial fibrillation.</AbstractText>A total of 351 patients with atrial fibrillation caused by cardiovascular diseases and idiopathic atrial fibrillation were assigned to amiodarone group (control group, 128 cases) and amiodarone combined with Shenmai Injection group (treatment group, 223 cases). The patients in the control group received intravenous injection of 150 mg amiodarone in 10 min, followed by intravenous drip infusion at 1 mg /min and 6 h later at 0.5 mg /min until 48 h or cardioversion. The patients in the treatment group received the same treatment of amiodarone, while in addition, they received an injection of Shenmai Injection of 100 mL simultaneously. Blood pressure, ventricular rate, and cardioversion were observed.</AbstractText>The total efficiency rate was 98% (control group) and 99% (treatment group) (P>0.05). The mean ventricular rate decreased 23% and 31% in the control group and the treatment group, respectively (P<0.05). The mean cardioversion time of the two groups was 570±211 min and 351±123 min, respectively (P<0.05). Only mild side effects were observed in both groups.</AbstractText>Compared with amiodarone, amiodarone combined with Shenmai Injection takes effect more quickly with low side effects on the treatment of atrial fibrillation.</AbstractText> |
5,238 | Evaluation of cardiac arrhythmia among athletes. | Due to the growing awareness of exercise-related arrhythmias and improved sensitivity of diagnostic modalities, physicians are increasingly faced with choices that may have life-changing impact for the athlete. This article surveys recent research and expert opinion addressing benign and pathogenic cardiac changes underlying arrhythmias in athletes. |
5,239 | Assessment of left atrial appendage function during sinus rhythm in patients with hypertrophic cardiomyopathy: transesophageal echocardiography and tissue doppler study. | The incidence of systemic thromboembolism is high in patients with hypertrophic cardiomyopathy (HCM). The authors hypothesized that vulnerability to such vascular events could be caused by depressed left atrial appendage (LAA) function during normal sinus rhythm (SR). The aim of this cross-sectional study was to investigate LAA contractile function during SR in patients with HCM.</AbstractText>LAA function was assessed in 62 patients with HCM in SR and compared with that in 53 age-matched and sex-matched controls. Patients with histories of atrial fibrillation and documented episodes of paroxysmal atrial fibrillation on 24-hour Holter monitoring and depressed left ventricular ejection fractions (<50%) were excluded. Multiplane transesophageal echocardiography was performed for determination of the morphology and function of the LAA.</AbstractText>LAA thrombi were present in five patients (8%) with HCM. LAA emptying and filling Doppler velocities were significantly depressed in the HCM group. LAA emptying and filling velocities were negatively correlated with age in controls (r = -0.4, P = .005), but these velocities were not associated with age in the HCM group. Moreover, LAA velocities were not associated with left ventricular mass index, left ventricular outflow tract gradient, or the degree of diastolic dysfunction in the HCM group. All Doppler tissue imaging velocities obtained from LAA walls were also significantly depressed in the HCM group.</AbstractText>LAA thrombus formation was not rare in this patient population. The significantly depressed LAA filling and emptying velocities in SR may predispose patients with HCM to thromboembolic events. The depressed Doppler tissue imaging LAA parameters in patients with HCM may indicate the presence of a possible intrinsic atrial myopathy. Thromboembolic risk should be taken into account, and the evaluation of LAA morphology and function by transesophageal echocardiography might become a component of routine workup in patients with HCM in the future.</AbstractText>Copyright © 2010 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
5,240 | Risk of cardiac arrhythmias and conduction abnormalities in patients with acute myocardial infarction receiving packed red blood cell transfusions. | Although transfusion has been linked to the development of atrial fibrillation (AF) in cardiac surgical patients, this association has not been investigated in patients with acute myocardial infarction (AMI). Evidence supports an inflammatory mechanism in the development of AF, and red cell transfusions also elicit an inflammatory response. We therefore sought to evaluate whether packed red blood cell transfusion increases the risk of AF, ventricular tachycardia (VT), and other arrhythmias and conduction abnormalities in patients with AMI.</AbstractText>This is a retrospective study on patients with AMI and no prior history of AF, admitted to a critical care area and entered in Project Impact database from 08/2003-12/2007. Primary outcome measures were new-onset cardiac arrhythmias or conduction disturbances.</AbstractText>Transfused patients had significantly higher incidences of AF (4.7% vs 1.3%, P = .008), cardiac arrest (9.5% vs 1.7%, P < .001) and heart block (3.4% vs 0.1%, P < .001), and a trend toward a higher incidence of VT (3.4% vs 1.3%, P = .058). Multivariate regression analysis confirmed transfusion as an independent risk factor for "non-lethal" cardiac events (AF/heart block; odds ratio [OR], 4.7 [1.9-11.9]; P = .001), "lethal" events (VT/cardiac arrest; OR, 2.4 [1.1-5]; P = .016), and all cardiac events (OR, 2.8 [1.5-65.1]; P = .001). Transfused patients had significantly longer length of stay (P < .0001) and significantly higher mortality rates than nontransfused patients (OR, 3 [1.7-5.5]; P < .001).</AbstractText>Packed red blood cell transfusion is independently associated with an increased risk of new-onset cardiac arrhythmias and conduction abnormalities in the setting of AMI, even after controlling for traditional risk factors.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,241 | Fetal right ventricular myocardial function is better preserved by fibrillatory arrest during fetal cardiac bypass. | Protection and preservation of fetal myocardial function are important for successful fetal intracardiac repair. Our objective was to determine fetal biventricular cardiac performance after two cardiac-arrest techniques.</AbstractText>Three groups of midterm ovine fetuses underwent 90-minute bypass. A control group (no arrest shams, n = 3), and two groups that included 20 minutes of arrest, using fibrillatory (n = 3) or blood cardioplegia (n = 3), were compared. Blood cardioplegia consisted of 4:1 cold blood to crystalloid solution induction every 10 minutes, followed by a warm shot terminal dose before clamp removal. Myocardial function variables from biventricular intracardiac pressure catheters, and 3-axes cardiac sonomicrometry, fetal hemodynamics, and arterial blood gases were continuously recorded. Fetal myocardium was collected for troponin-I analysis at 90 minutes. Statistical analysis was by two-way analysis of variance for repeated measures.</AbstractText>Compared with sham, right ventricular myocardial contractility was reduced with plegia but not fibrillation at 90 minutes after arrest: dP/dt max (511 ± 347 vs 1208 ± 239, p < 0.01) and preload-recruitable stroke work (7.2 ± 8.5 vs 32.3 ± 14.6, p < 0.01). Right ventricular end diastolic pressure-volume relationship (ventricular stiffness) worsened by 90 minutes for plegia vs fibrillation (0.84 ± 0.18 vs 0.25 ± 0.16, p < 0.05). There were no differences in left ventricle performance between groups. Fetal heart rate increased in shams by 30 minutes after arrest compared with both arrest groups (p < 0.05). Right ventricular troponin-I degradation increased with plegia, but not fibrillation, compared with sham (p < 0.05).</AbstractText>In vivo, fetal right ventricular contractile function deteriorates with a common blood-plegia regimen. Fibrillatory arrest better preserves right ventricular function, the dominant ventricle in fetal life, for short arrest periods.</AbstractText>Copyright © 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,242 | Early afterdepolarizations and cardiac arrhythmias. | Early afterdepolarizations (EADs) are an important cause of lethal ventricular arrhythmias in long QT syndromes and heart failure, but the mechanisms by which EADs at the cellular scale cause arrhythmias such as polymorphic ventricular tachycardia (PVT) and torsades de pointes (TdP) at the tissue scale are not well understood. Here we summarize recent progress in this area, discussing (1) the ionic basis of EADs, (2) evidence that deterministic chaos underlies the irregular behavior of EADs, (3) mechanisms by which chaotic EADs synchronize in large numbers of coupled cells in tissue to overcome source-sink mismatches, (4) how this synchronization process allows EADs to initiate triggers and generate mixed focal reentrant ventricular arrhythmias underlying PVT and TdP, and (5) therapeutic implications. |
5,243 | Recurrent ventricular arrhythmias and myocardial infarctions associated with cocaine induced reversible coronary vasospasm. | Cocaine has become the most frequently used illicit drug among patients presenting to emergency departments worldwide. Although acute myocardial infarction is the most common reported cardiovascular manifestation in this setting, there are many other potential cardiotoxic effects of cocaine use including coronary artery spasm, arrhythmia, and sudden death. We report the case of a 54 year-old male with angiographically documented reversible coronary arterial spasm leading to severe life-threatening recurrent ventricular arrhythmias and electrocardiographic changes suggesting acute myocardial infarction secondary to cocaine use. Recurrent ventricular arrhythmias of this patient required implantation of a cardioverter-defibrillator which successfully treated following arrhythmia episodes. |
5,244 | Does atrial fibrillation affect plasma endothelin level? | Atrial fibrillation (AF) may result in endocardial endothelium dysfunction. The main objective of the study was to evaluate the plasma concentration of endothelin-1 (ET-1) during persistent AF and after sinus rhythm recovery following direct-current cardioversion and to assess the predictive value of ET-1 in AF patients.</AbstractText>The study group consisted of 43 patients with persistent AF and normal left ventricle systolic function who had undergone successful cardioversion. Blood samples were collected twice: 24 hours before and 24 hours after cardioversion. All patients were also examined in terms of sinus rhythm maintenance on the 30th day after cardioversion.</AbstractText>There were no differences in ET-1 plasma concentration between the persistent AF group and the control group (2.6 ± 2.9 fmol/mL vs 2.3 ± 4.5 fmol/mL, NS). Plasma ET-1 levels did not change within 24 hours after successful cardioversion (2.5 ± 2.8 fmol/mL vs 2.6 ± 2.9 fmol/mL, NS). There was no correlation between the baseline plasma levels of ET-1 in patients with persistent AF and sinus rhythm maintenance 30 days after cardioversion.</AbstractText>Persistent AF does not affect plasma ET-1 concentration in patients with normal left ventricle systolic function and with no symptoms of heart failure. There are no significant changes in plasma ET-1 level during the 24 hours after cardioversion.</AbstractText> |
5,245 | Active tissue factor and activated factor XI in circulating blood of patients with systolic heart failure due to ischemic cardiomyopathy. | Elevated clotting factors and thrombin generation have been reported to occur in patients with heart failure (HF). Circulating activated factor XI (FXIa) and active tissue factor (TF) can be detected in acute coronary syndromes and stable angina.</AbstractText>We investigated circulating FXIa and active TF and their associations in patients with systolic HF due to ischemic cardiomyopathy.</AbstractText>In an observational study, we assessed 53 consecutive patients, aged below 75 years, with stable HF associated with documented coronary artery disease (CAD). Atrial fibrillation, recent thromboembolic events, and current anticoagulant therapy were the exclusion criteria. Plasma TF and FXIa activity was determined in clotting assays by measuring the response to inhibitory monoclonal antibodies.</AbstractText>Coagulant TF activity was detected in 20 patients (37.7%), and FXIa in 22 patients (41.5%). Patients with detectable TF activity and/or FXIa were younger, had a history of myocardial infarction more frequently, significantly higher F1+2 prothrombin fragments, larger left atrium (LA) and right ventricular diastolic diameter, and higher right ventricular systolic pressure than the remaining subjects (P ≤ 0.01 for all). Circulating FXIa was positively correlated with F1+2 levels (r = 0.69; P < 0.001).</AbstractText>Circulating active TF and FXIa occurred in about 40% of patients with systolic HF due to ischemic cardiomyopathy. The presence of these factors was associated with enhanced thrombin formation. Associations between both factors and LA diameter and right ventricular parameters might suggest that TF and FXIa predispose to thromboembolic complications of HF.</AbstractText> |
5,246 | Intramural dyssynchrony and response to cardiac resynchronization therapy in patients with and without previous right ventricular pacing. | Right ventricular (RV) pacing is an iatrogenic cause of heart failure (HF) that has not been well studied. We assessed whether HF patients paced from the right ventricle (RVp) adversely remodel and respond to cardiac resynchronization therapy (CRT) in a similar way to HF patients without right ventricular pacing (nRVp).</AbstractText>Echocardiograms were performed before and ∼5 months after CRT in 31 RVp and 49 nRVp HF patients. Longitudinal intraventricular dyssynchrony using tissue Doppler imaging (TDI) was calculated as the standard deviation of time to peak systolic displacement by tissue tracking (SD-TT) of 12 segments. Longitudinal dyssynchrony within a wall (intramural dyssynchrony) was assessed by two methods: quantifying the number of segments with initial abnormal apical displacement (IMD score) and using a cross-correlation synchrony index (CCSI). Despite similar ejection fractions (EFs) of 28% prior to CRT, left ventricular end-diastolic volume was significantly smaller (143±54 vs. 183±62, P=0.004) in RVp. The standard deviation of time to peak systolic displacement by tissue tracking (83.4±34.9 vs. 67.9±26.6, P=0.03) and IMD score (3.1±1.8 vs. 1.3±1.7, P<0.001) were greater in RVp. Cardiac resynchronization therapy significantly improved EF and volumes in both groups. Ejection fraction increased more in RVp (12.8±9.2% vs. 7.4±7.6%, P=0.007). Intraventricular dyssynchrony and both measures of intramural septal dyssynchrony improved to a greater extent post-CRT in RVp.</AbstractText>Right ventricular pacing patients differ from nRVp HF patients in that they have smaller ventricles and greater intraventricular and intramural septal dyssynchrony. Right ventricular pacing HF patients respond better to CRT with greater improvements in EF, and intraventricular and intramural septal dyssynchrony.</AbstractText> |
5,247 | [Clinical applications of strain rate imaging for evaluation of left atrial function]. | Left atrial (LA) function plays an important role in patients with left ventricular dysfunction and atrial fibrillation, and has been assessed using several noninvasive methods. However, there are a number of limitations regarding clinical application, including the dependence of altered left ventricular hemodynamics, image quality, single plane assessment, and the tethering effect. Strain rate (SR) imaging is a novel echocardiographic technique for assessing LA function, which enables the quantification of LA function in patients with atrial fibrillation, hypertension, diabetes mellitus, obesity, atrial septal defect, dilated cardiomyopathy, and cardiac amyloidosis. Furthermore, SR imaging can identify LA dysfunction in patients with hypertension or diabetes mellitus, even in the absence of LA dilation or functional LA impairment assessed by conventional Doppler echocardiography and tissue Doppler imaging. LA deformation assessed by SR imaging is a predictor of the maintenance of a sinus rhythm after either electrical cardioversion or catheter ablation for atrial fibrillation. Recently, two-dimensional speckle tracking echocardiography has been used as a noninvasive, simple, and reproducible technique for assessing LA function in patients with either physiological or pathological left ventricular hypertrophy. LA dysfunction detected by either SR imaging or two-dimensional speckle tracking echocardiography may be associated with the development of heart failure, thromboembolism, and atrial fibrillation, and should undergo further investigations. In this review, the clinical applications of SR imaging for LA function evaluation are summarized. |
5,248 | Over 10 years with an implantable cardioverter-defibrillator - a long term follow-up of 60 patients. | Transvenous implantable cardioverter-defibrillators (ICD) have been implanted in Poland since 1995. As the method spreads it is important to consider its long-term benefits and disadvantages.</AbstractText>To assess survival, efficacy and complication rate in ICD patients, who received the device more than ten years earlier.</AbstractText>Retrospective analysis of 60 ICD patients implanted between 1995-1999.</AbstractText>There were 42 (70%) males, mean age 50.6 ± 16.4 years. In 59 patients ICD was implanted for sudden cardiac death (SCD) secondary prevention. Thirty eight patients (34 M, 63.3%) had coronary artery disease (CAD). The CAD was diagnosed in 89.5% of males and 10.5% of females (p〈 0.0001). Mean follow-up time was 75.4 ± 34.7 months. During this time 22 patients died (37%, 19 M, 3 F). Three deaths were SCD. Mean one-year mortality was 6.7%. Deaths were more frequent among males: 45.2% vs 16.7%, p〈 0.005. In CAD mortality was higher than in non-CAD patients (50% vs 13.6%, p〈 0.005). Appropriate ICD discharges in the ventricular fibrillation (VF) zone occurred in 35 (58%) patients, and in ventricular tachycardia (VT) zone - in 26 (43%) patients. Mean intervention rate per year was 3.7 for VF and 0.6 for VT. Complications occurred in 27 (45%) patients and 5 (8%) of them had no ICD intervention during follow-up. In 5 patients more than one complication was diagnosed. There were inappropriate discharges in 15 (25%) patients, 11 (18%) had electrical storm, and ICD-related infections were noted in 3 (5%) patients. During the perioperative period, lead revisions were done in 4 patients; in 3 with discharges induced by T-wave oversensing and in one with lead dislocation. Four cases of lead failure occurred during follow-up, requiring new lead implantation. In 4 patients, electrical storm (3 patients) and supraventricular tachycardia with ICD discharges (1 patient) were treated with radiofrequency ablation. Only 10 (17%) patients did not demonstrate any ICD interventions or ICD-related complications.</AbstractText>1. ICD interventions caused by malignant ventricular arrhythmias occurred in 75% patients with the device implanted more than 10 years earlier. 2. Almost a half of the analysed population suffered from complications and side effects related to implanted ICD and they were present in 8% of subjects without ICD intervention. Neither ICD interventions nor device-related adverse events were recorded in 17% of patients.</AbstractText> |
5,249 | New-onset versus chronic atrial fibrillation in acute myocardial infarction: differences in short- and long-term follow-up. | Atrial fibrillation (AF) occurs commonly in patients with acute myocardial infarction (AMI) and has been established as a marker of adverse prognosis. There are only few clinical trials that investigate differences between new-onset and chronic AF in AMI. We hypothesize that chronic AF is associated with an increased rate of adverse short- and long-term outcomes.</AbstractText>In a single center study, over a period of 28 months, 375 consecutive patients with AMI were included [337 patients without AF (89.9%) and 38 with AF (10.1%)]. As much as 16 patients had new-onset AF (42.1%) and 22 had chronic AF (57.9%). Patients with severe coronary artery disease develop AF more often in AMI, and the existence of AF was associated with a poor prognosis. Compared to patients with new-onset AF, chronic AF was more frequently associated with advanced age (75 vs. 70 years, p not significant), reduced left ventricular ejection fraction (44.8 vs. 54.0%, p < 0.05) and NSTEMI (63.6 vs. 36.4%, p < 0.05). Only chronic AF resulted in increased in-hospital death (18.2 vs. 0.0%; p < 0.005) at the 2-year follow-up, 14 patients with AF died (63.6%), predominantly due to cardiovascular reasons.</AbstractText>Our results indicate that patients with chronic AF had a higher incidence of in-hospital death than those with new-onset AF or without. Chronic AF includes a group of older and sicker patients than their counterparts with new-onset AF. Understanding these findings may ultimately lead to better care of patients with this arrhythmia to prevent the development of the underlying atrial substrate in chronic AF patients and to improve their otherwise worse prognosis.</AbstractText> |
5,250 | Alcohol ablation at the posterior papillary muscle prevents ventricular fibrillation in swine without affecting mitral valve function. | Radiofrequency ablation at the posterior papillary muscle (PM) significantly reduced ventricular fibrillation (VF) inducibility in rabbits and dogs, suggesting that PM may be involved in the generation of VF. However, the effect of ablation at the PM on VF inducibility remains unknown in normal intact swine hearts because in this species radiofrequency energy delivered at PM provoked incessant VF.</AbstractText>Twelve anesthetized swine underwent median sternotomy. Under the ultrasonographic guidance, chemical ablation was performed via injection of dehydrated alcohol into the base of the posterior PM (group PM, n = 6) or anterior wall (control group, n = 6) in the left ventricle. Ventricular fibrillation inducibility and mitral valve function were measured pre- and post-ablation. Hearts were explanted and the ablated myocardium was stained with haematoxylin and eosin. Ventricular fibrillation inducibility was significantly decreased from 100 ± 0% pre-ablation to 11.9 ± 7.8% post-ablation in group PM (P = 0.001), whereas it was not statistically different in the control group (100 ± 0 vs. 92.9 ± 7.1%, pre-ablation vs. post-ablation). Haemorrhage and cellular necrosis was observed in the centre of ablated myocardium and no significant mitral regurgitation was observed following ablation at the posterior PM.</AbstractText>Alcohol ablation of the left posterior PM reduced VF inducibility in normal intact swine hearts, with no significant mitral regurgitation. This suggests that the posterior PM may be involved in the generation of VF, and the recurrence of VF may be prevented by chemical ablation at the posterior PM.</AbstractText> |
5,251 | [Coronary artery dissection in young adults]. | Two young patients, a 23-year-old man and a 30-year-old woman, without any risk factors for coronary artery disease, apart from the woman being a smoker, were admitted to our hospital because of acute myocardial infarction (MI) due to spontaneous dissection of a coronary artery (SDCA). The first patient developed acute chest pain while playing soccer. The second patient had unspecific chest pain in the preceding four weeks and was admitted after successful resuscitation with ventricular fibrillation. Both patients were treated with primary percutaneous coronary intervention. SDCA is a rare cause of MI and sudden cardiac death with an indistinguishable presentation due to plaque rupture. The majority of cases occur in young women. It is associated with various pathophysiological mechanisms and can manifest during pregnancy, in the postpartum period, in collagen diseases, cocaine abuse, severe hypertension, smoking, oral contraceptives, heavy exercise, or vasospasm. Treatment, pharmacological or with revascularization, is based on the severity of the dissection. Patients who survive the acute phase have good long-term prognoses. |
5,252 | Assessing the impact of prehospital intubation on survival in out-of-hospital cardiac arrest. | There is a developing body of literature documenting adverse survival outcome of out-of-hospital endotracheal intubation for critical multiple trauma and head injury patients.</AbstractText>To compare the rates of survival to hospital admission and discharge of nontraumatic out-of-hospital cardiac arrest (OHCA) patients who received successful out-of-hospital endotracheal intubation and those who were not intubated.</AbstractText>We conducted a retrospective analysis from an ongoing database of OHCA patients brought to a large suburban tertiary care emergency department by paramedic services between 1995 and 2006. We dichotomized patients by whether they were successfully endotracheally intubated or not prior to hospital arrival. Utstein style cardiac arrest variables were abstracted for all cases. All survivors to hospital admission were reviewed to exclude those patients in whom intubation was not attempted or unnecessary, such as those who had successful first-shock recovery of spontaneous circulation. We used chi square and logistic regression techniques for analysis, using survival to discharge as the primary outcome and survival to admission as a secondary outcome.</AbstractText>There were 1,515 total cases with 33 early survivors excluded. Overall, 1,220 (86.2%) were intubated; of those intubated, 270 (20.2%) survived to admission and 93 (7.0%) survived to discharge. Upon univariate analysis, there was no difference in survival between intubated and non intubated groups (6.5% vs 10.0%, OR = 0.63, 95% CI 0.37,1.08). For patients initially in ventricular fibrillation/ventricular tachycardia (VT/VF), in a multivariate Logit model, intubation significantly decreased survival to discharge, adjusted odds ratio (OR) = 0.52 (95% confidence interval 0.27, 0.998). Intubated non-VF patients were more likely to survive to admission, adjusted OR 2.96 (1.04, 8.43), but not to discharge (1.8% vs. 1.0%, p = 1.0).</AbstractText>This observational study in an unselected population shows that patients in VF/VT arrest who underwent out-of-hospital intubation were less likely to survive to discharge than those not intubated. Out-of-hospital intubation of patients with non-VF arrest was associated with an increased rate of survival to admission, but not survival to discharge. Future prospective studies are needed to define the role of out-of-hospital endotracheal intubation in cardiac arrest patients.</AbstractText> |
5,253 | Ventricular fibrillation associated with early repolarization in a patient with thyroid storm. | We present a case of a 69-year-old male who was hospitalized for the treatment of thyroid storm due to Grave's disease, who presented with unexpected ventricular fibrillation (VF). The possible etiology was early repolarization (ER), characterized by J-point elevation in inferior and posterolateral leads, unmasked by the attenuation of beta-adrenergic effect with normalization of thyroid hormones and following the administration of a beta-blocker. Our case focuses attention on the occurrence of VF in a patient with ER during the treatment of hyperthyroidism, which to our knowledge is the first such report. |
5,254 | B-type natriuretic peptide is predictive of postoperative events in orthopedic surgery. | [Corrected] Clinical assessment is not always sufficient to predict postoperative (PO) cardiac complications. B-type natriuretic peptide (BNP) has an important prognostic value in patients with heart failure. Its value as a predictor of events in orthopedic surgeries has not yet been tested.</AbstractText>To assess the value of BNP in predicting cardiac complications in the PO period of orthopedic surgeries.</AbstractText>A total of 208 patients undergoing surgical treatment of femur fracture and hip or knee arthroplasty were prospectively evaluated. Of these, 149 (71.6%) were women and the mean age was 72.6 ± 8.8 years. In the preoperative period, the patients underwent conventional clinical assessment and their surgical risk was estimated according to the American Society of Anesthesiologists' (ASA) classification. BNP was determined in the preoperative period, and its ability to predict PO cardiac events (death; acute myocardial infarction; unstable angina; atrial fibrillation; ventricular tachycardia; or heart failure) was analyzed using multivariate logistic regression analysis.</AbstractText>Seventeen patients (8.0%) experienced cardiac events. Median BNP was significantly higher in these patients in comparison to those without cardiac events (93 [interquartile range 73-424] vs 26.6 [13.2-53.1], p = 0.0001). BNP was the main independent predictor of events (p = 0.01). The ASA classification was not an independent predictor. Analysis of the ROC curve demonstrated that for a cut-off point of 60 pg/mL, BNP showed sensitivity of 76.0% and specificity of 79.0% in the prediction of events, with an area under the curve of 83.0%.</AbstractText>BNP is an independent predictor of PO cardiac events in orthopedic surgeries.</AbstractText> |
5,255 | Optimizing ICD programming for shock reduction. | With the increasing numbers of patients with implantable cardioverter/defibrillators for primary prevention (PP), the topic of inappropriate therapy becomes more and more important. If a shock intervention, e.g. for rapidly conducted atrial fibrillation or fast VT (FVT), represents the first reminder of the implantable cardioverter/defibrillator (ICD), the adherence to the therapy will decrease. Moreover, anxiety to receive the next inappropriate ICD Rx is able to initiate a bad quality of life or depression. Starting with the PainFREE Rx II Trial results, the programming of antitachycardia pacing was able to terminate even fast ventricular arrhythmia, i.e. ≥ 188 bpm, in three of four episodes. Thereafter, several studies evaluated whether a prolongation in ventricular tachyarrhythmia (VT) detection is able to reduce unnecessary ICD Rx owing to nonsustained VT. The PREPARE trial evaluated this concept in a cohort of PP patients. This nonrandomized study compared a historical control group to patients with a prolonged detection interval. The results underline the idea that an extension in detection time leads to a significant decrease in ICD Rx for supra- as well as VT. The RELEVANT study investigated in a randomized fashion the outcome of an increase in detection time in nonischemic patients under CRT including an ICD. The findings clearly demonstrated a reduction in ICD Rx as well as hospital admissions, significantly. Currently, the ADVANCE III trial investigates a 30/40 interval detection compared to 18/24 for FVT in prospective randomized fashion in patients for primary or secondary prevention including all ICD devices. |
5,256 | Chronotropic incompetence and its relation to exercise intolerance in hypertrophic cardiomyopathy. | Diminished functional capacity is common in hypertrophic cardiomyopathy (HCM), although the underlying mechanisms are complicated. We studied the prevalence of chronotropic incompetence and its relation to exercise intolerance in patients with HCM.</AbstractText>Cardiopulmonary exercise testing was performed in 68 patients with HCM (age 44.8 ± 14.6 years, 45 males). Chronotropic incompetence was defined by chronotropic index (heart rate reserve)/(220-age-resting heart rate) and exercise capacity was assessed by peak oxygen consumption (peak Vo(2)).</AbstractText>Chronotropic incompetence was present in 50% of the patients and was associated with higher NYHA class, history of atrial fibrillation, higher fibrosis burden on cardiac MRI, and treatment with β-blockers, amiodarone and warfarin. On univariate analysis, male gender, age, NYHA class, maximal wall thickness, left atrial diameter, peak early diastolic myocardial velocity of the lateral mitral annulus, history of atrial fibrillation, presence of left ventricular outflow tract obstruction (LVOTO) at rest, and treatment with beta-blockers were related to peak Vo(2). Peak heart rate during exercise, heart rate reserve, chronotropic index, and peak systolic blood pressure were also related to peak Vo(2). On multivariate analysis male gender, atrial fibrillation, presence of LVOTO and heart rate reserve were independent predictors of exercise capacity (R(2) = 76.7%). A cutoff of 62 bpm for the heart rate reserve showed a negative predictive value of 100% in predicting patients with a peak Vo(2) <80%.</AbstractText>Blunted heart rate response to exercise is common in HCM and represents an important determinant of exercise capacity.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,257 | Left ventricular diastolic function and right atrial size are important rhythm outcome predictors after intraoperative ablation for atrial fibrillation. | Left ventricular (LV) diastolic function and right atrial (RA) size are not routinely included in preoperative echocardiographic examination in patients undergoing cardiac surgery with concomitant ablation for atrial fibrillation (AF).</AbstractText>To investigate the role of echocardiographic variables including LV diastolic function and RA area in long-term rhythm outcome prediction, in patients with documented AF undergoing intraoperative ablation concomitant to coronary artery bypass grafting (CABG).</AbstractText>Thirty-five consecutive patients, scheduled for CABG, and with a history of paroxysmal or permanent AF for 8.5 ± 11.3 years (mean ± SD) (median 5.8 years), were included in this prospective study. Echocardiography was performed prior to and 2.3 ± 0.4 years after the surgical procedure.</AbstractText>Both LA and RA areas, LV diastolic function, paroxysmal AF, and sinus rhythm (SR) preoperatively were associated with SR at long-term follow-up. In the multivariate analysis, RA area (P = 0.004), and decreased LV diastolic function preoperatively, measured as the maximal LV long-axis relaxation velocity (P = 0.02), predicted SR at follow-up.</AbstractText>RA size and LV diastolic function may be important variables in prediction of long-term rhythm outcome after intraoperative ablation for AF.</AbstractText>© 2010, Wiley Periodicals, Inc.</CopyrightInformation> |
5,258 | Ischemia-induced prominent J waves in a patient with Brugada syndrome. | A 75-year-old man was admitted to our hospital in January 2010 for evaluation of syncope and abnormal ECG. ECG showed type 1 ST elevation in lead V(1) and he was diagnosed as Brugada syndrome. During cardiac catheterization, baseline coronary angiography was normal, but intracoronary ergonovine maleate induced spasms of the right and left coronary arteries concomitant with chest pain and ST elevation on ECG. J waves were accentuated or newly developed. Soon after an intracoronary injection of nitroglycerin, chest pain was relieved and ischemia-induced J wave disappeared and the ST segment returned to the same morphology as baseline. Extrastimuli induced ventricular fibrillation. He received an implantable cardioverter-defibrillator. He was also treated with Ca antagonist and isosorbide dinitrate and has had an uneventful course for 5 months. |
5,259 | Increase in internal defibrillation threshold during acute myocardial infarction. | A 67-year-old man suffered an acute anteroseptal myocardial infarction complicated by multiple episodes of ventricular fibrillation, which were not systematically defibrillated by maximum, internal 35-J shocks delivered by an implanted cardioverter defibrillator (ICD). He had suffered from acute inferior myocardial infarction 6 years earlier, complicated with sustained polymorphic ventricular tachycardia (VT). Due to inducibility of sustained VT on an electrophysiologic study, an ICD was implanted. Defibrillation testing performed after healing of anteroseptal infarction was successful with a 10-J safety margin, suggesting that acute myocardial ischemia transiently elevated the internal defibrillation threshold. |
5,260 | Early and late cardiac ventricular reverse remodeling after catheter ablation for lone paroxysmal atrial fibrillation. | We sought to explore ventricular function in patients with lone paroxysmal atrial fibrillation (AF) and determine the mid- and long-term impact of pulmonary vein isolation on cardiac remodeling.</AbstractText>The relationship between tachyarrhythmia and ventricular dysfunction is still a matter of debate. Tachycardia-induced cardiomyopathy is defined as reversible myocardial dysfunction following treatment for tachyarrhythmia.</AbstractText>We prospectively studied 31 patients (56.4 ± 10 years) presenting with paroxysmal-AF who were treated successfully by catheter ablation and 15 age-matched controls. Left and right ventricular functions were assessed by echocardiography at baseline and at 3-month and 1-year follow-up.</AbstractText>In AF-patients, LV-function was slightly lower at baseline than controls (LV-ejection fraction was 60% versus 64%; P = 0.06). More impressive, systolic peak velocity on Doppler tissue imaging was 9 cm/s in AF patients (versus 12 cm/s; P = 0.0004). LV global longitudinal strain was also significantly different between the two groups (patients: -16% versus controls: -19%; P = 0.005). At 1-year follow-up, most functional parameters significantly improved in the AF-patients and no longer differed from the controls. Right ventricular (RV) function was also depressed in AF patients at baseline. At 1-year follow-up, tissue Doppler showed improvement in RV-S' (+27%, P = 0.007) and RV peak systolic strain (+36%, P<0.0001) and became comparable to controls.</AbstractText>We demonstrate that some degree of arrhythmic cardiomyopathy exists in patients presenting with lone paroxysmal-AF. Catheter ablation improved RV and LV functions. Longitudinal function is the most sensitive component of ventricular systole to monitor when looking for this cardiac reverse remodeling.</AbstractText>Copyright © 2010 Elsevier Masson SAS. All rights reserved.</CopyrightInformation> |
5,261 | Tricuspid regurgitation in patients with severe mitral regurgitation and normal left ventricular ejection fraction: risk factors and prognostic implications in a cohort of 895 patients. | Although tricuspid regurgitation (TR) is common in patients with mitral regurgitation (MR), its frequency, determinants and prognostic implications in those with severe MR and a normal left ventricular ejection fraction (LVEF) are not fully known. The study aim was to evaluate the risk factors for, and prognostic implications of, TR in patients with severe MR and a normal LVEF.</AbstractText>In this retrospective cohort study, the authors' echocardiographic database for the period between 1993 and 2003 was screened for patients with severe MR and LVEF > or = 55%. Chart reviews were performed for clinical, pharmacological and surgical details, while survival was analyzed as a function of TR severity.</AbstractText>Among 895 patients with severe MR and normal LVEF, 510 (57%) had grade > or = 2+ TR, while 219 (24%) had grade 3 or 4+ TR. Those patients with grade > or = 2+ TR were older (p < 0.0001), more likely to be female (p < 0.0001), and had a higher right ventricular systolic pressure (RVSP) (p < 0.0001). After adjusting for group differences (except for atrial fibrillation), grade > or = 2+ TR was associated with a higher mortality (relative risk 1.4, 95% confidence interval 1.1-1.8, p = 0.02). Mitral valve surgery was associated with a better survival in those with grade > or = 2+TR (p = 0.0003).</AbstractText>Significant TR is a frequent occurrence in patients with severe MR and a normal LVEF, and is associated with older age, female gender, and a higher RVSP. TR is independently associated with a higher mortality, while mitral valve surgery seems to offer a survival benefit.</AbstractText> |
5,262 | [Characteristics and the prognosis of patients with acute heart failure in current clinical practice]. | Analysis of predefined characteristics and outcomes in a non-selected population of patients hospitalized for acute heart failure (AHF) in Slovakia.</AbstractText>We conducted a nationwide prospective multicenter survey with 860 consecutive patients enrolled in 11 hospitals throughout Slovakia--two centres with a non-stop catheterization service, two central and 7 regional hospitals. Relevant data of 78 characteristics in 9 categories were collected during 3 months (between 1 May 2009 and 31 July 2009). There was a specific form designed for this survey. Collected data were then transferred into the electronic database and statistically analysed.</AbstractText>Mean age was 72 years, 81% of patients were in NYHA class III/IV (52% male). The majority of patients were admitted with decompensated heart failure (68.4%), frequency of cardiogenic shock was 0.3%. New-onset AHF (AHF de novo) was diagnosed in 31.1%, of which 20.8% was due to acute coronary syndromes. Coronary heart disease was the predominant primary aetiology of AHF (67%), followed by almost equally represented hypertension (10.5%), valvular disease (10%) and dilated cardiomyopathy (9%). Hypertension was referred as the most frequent comorbidity (82%), followed by atrial fibrillation (48%), diabetes mellitus (42%), history of renal failure (31%) and with anaemia at admission (38%). Rales were the dominant physical sign (69.9%). Systolic blood pressure greater than 140 mm Hg was present in 37.8% and QRS length > 120 ms in 21.4% of patients. Preserved left ventricular ejection fraction (> or = 40%) was observed in 57% out of 70% documented cases in the whole survey. 23.3% of patients had a history of coronary angiography. 84.3% of patients received intravenous treatment, diuretics, nitrates and inotropes were given to 82.2%, 18% and 6%, respectively. The number of patients with cardiac resynchronization therapy (CRT), with or without defibrillator function, was 0.9%. Mean length of stay was 9.2 days and in-hospital mortality was 9.1%. At discharge, 76% of patients were on angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARB), 62% were using beta-blockers (BB), however the doses of drugs were lower then recommended values.</AbstractText>Results of the survey are comparable with other observational studies, surveys and large registries. Although the percentage of patients with ACE-I/ARB and BB at discharge seems promising, there is still area for improvement in AHF patients health care.</AbstractText> |
5,263 | [Changes in NT-proBNP levels in patients with atrial fibrillation related to heart failure]. | NT-proBNP, a well-established diagnostic and prognostic marker in clinical practice, is significantly elevated in individuals with atrial fibrillation (AF), even in absence of heart failure or major structural heart disease.</AbstractText>The aim of this study was to determine the cut-off value of NT-proBNP for diagnosis of heart failure in individuals with atrial fibrillation.</AbstractText>We compared 44 patients (25 male/19 female) with AF and concomitant overt heart failure [age 76 (62-82) years; median (interquartile range - IQR)] versus 29 patients (16 male/13 female) with AF with no signs of heart failure [age 59 (50-67) years; median (IQR)]. We considered the underlying causes of heart failure and its severity, comorbidities, echocardiographic and selected laboratory parameters, the body mass index as well as the treatment at discharge. We determined the cut-off value for heart failure and major structural heart disease using ROC curve analysis.</AbstractText>Median NT-proBNP in the group of patients with AF and concomitant heart failure was 3 218 ng/l (IQR 1 758-7 480 ng/l) vs 981 ng/l (IQR 431-1 685 ng/l) in the group of patients with AF with no signs of heart failure; this difference was statistically significant (p < 0.001). The level of NT-proBNP higher than 1 524 ng/l in patients with AF was diagnostic of major structural heart disease and pointed towards a possible heart failure (sensitivity 80%, specificity of 76%, accuracy 78%, positive predictive value 83%, negative predictive value 71%). The NT-proBNP levels significantly correlated with age (p < 0.001), left atrial diameter (p < 0.01) and furosemide dose at discharge (p < 0.05). The NT-proBNP levels significantly negatively correlated with left ventricular ejection fraction (p < 0.001) and body mass index (p < 0.05).</AbstractText>We found out that NT-proBNP is significantly elevated in patients with AF with preserved left ventricular function and in absence of heart failure and significantly correlates with age, left ventricular ejection fraction, left atrial diameter, body mass index and the furosemide dose necessary to achieve cardiac compensation. Furthermore, we determined the NT-proBNP cut-offvalue predictive of a possible heart failure in patients with AF.</AbstractText> |
5,264 | Syncope, widened QRS interval, and left ventricular systolic depression: coincident with propafenone therapy for atrial fibrillation. | We report the case of a 46-year-old man who developed syncope, a widened QRS interval, and depressed left ventricular systolic function during propafenone therapy for atrial fibrillation. These acute findings may have been consequent to an increased dosage of propafenone combined with heavy alcohol consumption that led to decreased metabolism of propafenone. In addition, propafenone is known to interfere with liver function, although this patient's test results showed scant evidence of liver abnormalities. Yet another possible factor is the genetic spectrum in the metabolism of propafenone and other class I antiarrhythmic agents. When propafenone is prescribed, we recommend advising patients that alcohol consumption and interactions with other drugs can lead to increased levels of the antiarrhythmic agent, with resultant toxicity that can lead to adverse cardiovascular effects. Patients taking propafenone should also undergo periodic liver function testing. Finally, attention should be paid to voluntary or official recalls of specific antiarrhythmic medications that are of unreliable quality or potency. |
5,265 | [Return of sinus rhythm in permanent atrial fibrillation patients at the time of the testing defibrillation during cardioverter-defibrillator implantation]. | Among patients, who underwent implantable cardioverter-defibrillator (ICD) implantation procedure, there are some, who have permanent atrial fibrillation (AF). There is a theoretical possibility of return of sinus rhythm at these patients during ventricular defibrillation testing at the time of the ICD implantation procedure. The aim of the study was to attempt to find agents which can promote return of sinus rhythm at the time of the defibrillation testing during ICD implantation.</AbstractText>Seventy-two (mean age 65.8 years, 60 men) of the 611 patients (mean age 63.3 years, 501 men) who underwent ICD induction over this period had permanent AF before and at the time of the procedure.</AbstractText>The return of sinus rhythm was observed in 17 patients (Group A, mean age 64.2 years, 14 men) during ICD implantation, at the time of the defibrillation testing. The return of sinus rhythm after ICD intervention could be associated with presence of 2-coil electrode (p < 0.001), with lower left atrial diameter (p < 0.001), with lower NYHA class (p < 0.05) and greater use of antiarrhythmic drugs (p < 0.025).</AbstractText>Atrial fibrillation was present in 11.7% of 611 ICD patients. We observed the return of sinus rhythm after ICD intervention in 2.7% persons. The return of sinus rhythm could be associated with presence of 2-coil electrode, lower left atrial diameter, lower NYHA class and greater use of antiarrhythmic drugs. To prevent embolic complication oral anticoagulation should be standard treatment in this group of patients.</AbstractText> |
5,266 | Superior vena cava syndrome: A rare complication of percutaneous nephrolithotripsy laser lithotripsy. | To describe a case of acute superior vena cava syndrome during percutaneous nephrolithotomy (PCNL), and to review the associated clinical features, management and complications.</AbstractText>A 34-year-old man, diagnosed as right renal calculi and nodal tachycardia, was admitted to receive percutaneous nephroscope laser lithotripsy. Shortly after stone disintegration, he suffered acute hypoxic and hypotension, and showed cyanoderma of face and chest skin, ocular proptosis, jugular filling and ventricular fibrillation. Dopamine and adrenaline was intravenously injected. The patient was turned over to supine position and external cardiac massage and electric defibrillation were carried out immediately. The patient finally cardioverted. His vital signs subsequently became stable and cyanoderma faded. The patient was eventually discharged from the intensive care unit three days following the event.</AbstractText>Severe complications such as cardiac arrest could happen during PCNL. Close monitoring the vital signs is essential for early finding and quick response to rescue.</AbstractText> |
5,267 | Evaluation of noncontact mapping by comparison with simultaneous multisite contact recordings in acute ischemic ventricular fibrillation. | The study aim was to determine the utility of noncontact mapping in acute ischemic ventricular fibrillation, by direct comparison with simultaneously acquired multisite contact needle recordings.</AbstractText>Noncontact mapping has emerged as a promising tool to make percutaneous high-density intracardiac electrical recordings in clinical and research settings. Previous large-animal mapping studies of ischemic VF have used electrodes in contact with the fibrillating myocardium. A previous report of noncontact mapping in VF used a single intracardiac catheter to validate noncontact recordings.</AbstractText>We studied the spontaneous onset of VF in 8 sheep, after acute occlusion of the left anterior descending coronary artery. Simultaneous unipolar recordings of endocardial electrical activation were made with the most endocardial electrode of 32 transmural plunge needles (contact electrograms; CE), and an Ensite noncontact catheter in the left ventricle (noncontact virtual electrograms; NCVE). The lag-shifted morphology cross-correlation between individual NCVE and CE pairs during VF was calculated.</AbstractText>The mean lag-shifted cross-correlation coefficient during manually selected sinus rhythm beats was 0.89 ± 0.006, and 0.80 ± 0.009 in VF (P < 0.05). The mean absolute time shift was 7.3 ± 0.5 ms in sinus rhythm, and 23.8 ± 0.9 ms in VF (P < 0.001). Fast Fourier transform demonstrated well-correlated dominant frequencies between CE and NCVE. VF myocardial activation maps of NCVE showed organized wavefronts, but dyssynchronous activation in CE.</AbstractText>These data demonstrate errors in activation timing and sequence with noncontact mapping more prominent during VF than sinus rhythm.</AbstractText>© 2010 Wiley Periodicals, Inc.</CopyrightInformation> |
5,268 | Early repolarization syndrome – a new electrical disorder associated with sudden cardiac death –. | Early repolarization (ER), consisting of a J-point elevation, notching or slurring of the terminal portion of the R wave (J wave), and tall/symmetric T wave, is a common finding on the 12-lead electrocardiogram. For decades, it has been considered as benign, barring sporadic case reports and basic electrophysiology research that suggested a critical role of the J wave in the pathogenesis of idiopathic ventricular fibrillation (VF). In 2007-2008, a high prevalence of ER in patients with idiopathic VF was reported and subsequent studies reinforced the results. This review summarizes the current state of knowledge concerning ER syndrome associated with sudden cardiac death.  |
5,269 | Long-term recording of cardiac arrhythmias with an implantable cardiac monitor in patients with reduced ejection fraction after acute myocardial infarction: the Cardiac Arrhythmias and Risk Stratification After Acute Myocardial Infarction (CARISMA) study. | Knowledge about the incidence of cardiac arrhythmias after acute myocardial infarction has been limited by the lack of traditional ECG recording systems to document and confirm asymptomatic and symptomatic arrhythmias. The Cardiac Arrhythmias and Risk Stratification After Myocardial Infarction (CARISMA) trial was designed to study the incidence and prognostic significance of arrhythmias documented by an implantable cardiac monitor among patients with acute myocardial infarction and reduced left ventricular ejection fraction.</AbstractText>A total of 1393 of 5869 patients (24%) screened in the acute phase (3 to 21 days) of an acute myocardial infarction had left ventricular ejection fraction ≤40%. After exclusions, 297 patients (21%) (mean±SD age, 64.0±11.0 years; left ventricular ejection fraction, 31±7%) received an implantable cardiac monitor within 11±5 days of the acute myocardial infarction and were followed up every 3 months for an average of 1.9±0.5 years. Predefined bradyarrhythmias and tachyarrhythmias were recorded in 137 patients (46%); 86% of these were asymptomatic. The implantable cardiac monitor documented a 28% incidence of new-onset atrial fibrillation with fast ventricular response (≥125 bpm), a 13% incidence of nonsustained ventricular tachycardia (≥16 beats), a 10% incidence of high-degree atrioventricular block (≤30 bpm lasting ≥8 seconds), a 7% incidence of sinus bradycardia (≤30 bpm lasting ≥8 seconds), a 5% incidence of sinus arrest (≥5 seconds), a 3% incidence of sustained ventricular tachycardia, and a 3% incidence of ventricular fibrillation. Cox regression analysis with time-dependent covariates revealed that high-degree atrioventricular block was the most powerful predictor of cardiac death (hazard ratio, 6.75; 95% confidence interval, 2.55 to 17.84; P<0.001).</AbstractText>This is the first study to report on long-term cardiac arrhythmias recorded by an implantable loop recorder in patients with left ventricular ejection fraction ≤40% after myocardial infarction. Clinically significant bradyarrhythmias and tachyarrhythmias were documented in a substantial proportion of patients with depressed left ventricular ejection fraction after acute myocardial infarction. Intermittent high-degree atrioventricular block was associated with a very high risk of cardiac death. Clinical Trial Registration- URL: http://www.ClinicalTrials.gov, Unique identifier: NCT00145119.</AbstractText> |
5,270 | Prognostic impact of atrial fibrillation progression in a community study: AFBAR Study (Atrial Fibrillation in the Barbanza Area Study). | The aim of the study is to describe the natural history of an unselected population of patients with atrial fibrillation (AF) currently attending primary care services in a single health-service area in Galicia, north-western Spain.</AbstractText>AFBAR is a transverse prospective study in which 35 general practitioners within one health-service area have enrolled patients diagnosed with AF who presented at their clinics during a three-month recruiting period. Primary endpoints are mortality or hospital admission. Here we report the results of the first 7-month follow-up period.</AbstractText>798 patients (421 male) were recruited; mean age of cohort was 75 years old. Hypertension was the most prevalent risk factor (77%). 87% of the patients were both overweight and obese. Permanent AF was diagnosed in 549 patients (69%). In the follow-up period, 16.4% of the patients underwent a primary endpoint and the overall survival was 98%. The following independent determinants of primary endpoint were identified: change in AF status (Hazard Ratio (HR) 2.89 (95% confidence interval (CI) 1.28-6.55); p=0.011); ischemic heart disease (IHD) (HR 2.78 (95% CI 1.51-5.13); p=0.001); pre-recruitment hospital admission (HR 2.22 (95% CI 1.18-4.19); p=0.013); left ventricular systolic dysfunction (HR 2.19 (95% CI 1.11-4.32); p=0.023); or AF-related complications (HR 1.98 (95% CI 1.10-3.56); p=0.022).</AbstractText>In the first 7-month follow-up period of patients with AF in a primary care setting the study identified several independent risk factors for mortality or hospital admission, i.e. change in AF status, ischemic heart disease, left ventricular systolic dysfunction, previous AF-related complications and hospital admission.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,271 | [Overlooked Wolff-Parkinson-White syndrome]. | An autopsy in a 28-year-old man did not explain the cause of sudden unexpected death. However, a history of episodes with tachycardia and dizziness and a reassessed previous electrocardiogram exhibiting ventricular pre-excitation was consistent with Wolff-Parkinson-White (WPW) syndrome. In this patient we believe that the occurrence of atrial fibrillation caused sudden cardiac death from ventricular fibrillation due to a short refractory period of an accessory atrioventricular pathway and a very rapid ventricular rate in atrial fibrillation. |
5,272 | Ventricular arrhythmia is predicted by sum absolute QRST integralbut not by QRS width. | There is a controversy regarding the association between QRS width and ventricular arrhythmias (VAs). We hypothesized that predictive value of the QRS width could be improved if QRS width were considered in the context of the sum magnitude of the absolute QRST integral in 3 orthogonal leads sum absolute QRST integral (SAI QRST). We explored correlations between QRS width, SAI QRST, and VA in primary prevention implantable cardioverter-defibrillator (ICD) patients with structural heart disease.</AbstractText>Baseline orthogonal electrocardiograms were recorded at rest in 355 patients with implanted primary prevention ICDs (mean age, 59.5 ± 12.4 years; 279 male [79%]). Patients were observed prospectively at least 6 months; appropriate ICD therapies because of sustained VA served as end points. The sum magnitude of the absolute QRST integral in 3 orthogonal leads (SAI QRST) was calculated.</AbstractText>During a mean follow-up of 18 months, 48 patients had sustained VA and received appropriate ICD therapies. There was no difference in baseline QRS width between patients with and those without arrhythmia (114.9 ± 32.8 vs 108.9 ± 24.7 milliseconds; P = .230). SAI QRST was significantly lower in patients with VA at follow-up than in patients without VA (102.6 ± 27.6 vs 112.0 ± 31.9 mV·ms; P = 0.034). Patients with SAI QRST (≤145 mV·ms) had a 3-fold higher risk of ventricular tachycardia (VT)/ventricular fibrillation (VF) (hazard ratio [HR], 3.25; 95% confidence interval [CI], 1.59-6.75; P = .001). In the univariate analysis, QRS width did not predict VT/VF. In the bivariate Cox regression model, every 1 millisecond of incremental QRS widening with a simultaneous 1 mV·ms SAI QRST decrease raised the risk of VT/VF by 2% (HR, 1.02; 95% CI, 1.01-1.03; P = .005).</AbstractText>QRS widening is associated with ventricular tachyarrhythmia only if accompanied by low SAI QRST.</AbstractText>Copyright © 2010 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,273 | Short-term autonomic denervation of the atria using botulinum toxin. | Major epicardial fat pads contain cardiac ganglionated plexi (GP) of the autonomic nervous system. Autonomic denervation may improve the success rate of atrial fibrillation (AF) ablation. This study was designed to elucidate the acute effects of blocking the right atrium-pulmonary vein (RA-PV) and left atrium-inferior vena cava (LA-IVC) fat pads on the electrophysiologic characteristics of the atrium and AF inducibility with a botulinum toxin injection.</AbstractText>Eight mongrel dogs were studied. The RA-PV and LA-IVC fat pads were exposed through a median thoracotomy. Botulinum toxin (BT, 50 U to each fat pad, n=6) or normal saline (NS, n=2) was injected in the entire area of two fat pads. The study protocol was applied before injection and repeated at 1, 2, 3, 4, and 5 hours thereafter. The sinus rate, ventricular rate during rapid atrial pacing with a cycle length of 50 ms, and AF inducibility were measured with and without vagal stimulation (VS). Bilateral cervical VS was applied (20 Hz, 0.2 ms, 5.6±2.0 V). AF inducibility was evaluated with burst pacing with 200 impulses at a 50-ms cycle length.</AbstractText>VS effects on the sinus node and AF inducibility were eliminated a few hours after injection of BT; these changes were not observed after injection of NS.</AbstractText>Short-term autonomic denervation of the atria was achieved by blocking the major epicardial GP with BT.</AbstractText> |
5,274 | Assessment of atrial electromechanical delay by tissue Doppler echocardiography in obese subjects. | Our aim was to evaluate whether atrial electromechanical delay measured by tissue Doppler imaging (TDI), which is an early predictor of atrial fibrillation (AF) development, is prolonged in obese subjects. A total of 40 obese and 40 normal-weight subjects with normal coronary angiograms were included in this study. P-wave dispersion (PWD) was calculated on the 12-lead electrocardiogram (ECG). Systolic and diastolic left ventricular (LV) functions, inter- and intra-atrial electromechanical delay were measured by TDI and conventional echocardiography. Inter- and intra-atrial electromechanical delay were significantly longer in the obese subjects compared with the controls (44.08 ± 10.06 vs. 19.35 ± 5.94 ms and 23.63 ± 6.41 vs. 5.13 ± 2.67 ms, P < 0.0001 for both, respectively). PWD was higher in obese subjects (53.40 ± 5.49 vs. 35.95 ± 5.93 ms, P < 0.0001). Left atrial (LA) diameter, LA volume index and LV diastolic parameters were significantly different between the groups. Interatrial electromechanical delay was correlated with PWD (r = 0.409, P = 0.009), high-sensitivity C-reactive protein (hsCRP) levels (r = 0.588, P < 0.0001). Interatrial electromechanical delay was positively correlated with LA diameter, LA volume index, and LV diastolic function parameters consisting of mitral early wave (E) deceleration time (DT) and isovolumetric relaxation time (IVRT; r = 0.323, P = 0.042; r = 0.387, P = 0.014; r = 0.339, P = 0.033; r = 0.325, P = 0.041; respectively) and, negatively correlated with mitral early (E) to late (A) wave ratio (E/A) (r = -0.380, P = 0.016) and myocardial early-to-late diastolic wave ratio (E(m)/A(m)) (r = -0.326, P = 0.040). This study showed that atrial electromechanical delay is prolonged in obese subjects. Prolonged atrial electromechanical delay is due to provoked low-grade inflammation as well as LA enlargement and early LV diastolic dysfunction in obese subjects. |
5,275 | Global incidences of out-of-hospital cardiac arrest and survival rates: Systematic review of 67 prospective studies. | The aim of this investigation was to estimate and contrast the global incidence and outcome of out-of-hospital cardiac arrest (OHCA) to provide a better understanding of the variability in risk and survival of OHCA.</AbstractText>We conducted a review of published English-language articles about incidence of OHCA, available through MEDLINE and EmBase. For studies including adult patients and both adult and paediatric patients, we used Utstein data reporting guidelines to calculate, summarize and compare incidences per 100,000 person-years of attended OHCAs, treated OHCAs, treated OHCAs with a cardiac cause, treated OHCA with ventricular fibrillation (VF), and survival-to-hospital discharge rates following OHCA.</AbstractText>Sixty-seven studies from Europe, North America, Asia or Australia met inclusion criteria. The weighted incidence estimate was significantly higher in studies including adults than in those including adults and paediatrics for treated OHCAs (62.3 vs 34.7; P<0.001); and for treated OHCAs with a cardiac cause (54.6 vs 40.8; P=0.004). Neither survival to discharge rates nor VF survival to discharge rates differed statistically significant among studies. The incidence of treated OHCAs was higher in North America (54.6) than in Europe (35.0), Asia (28.3), and Australia (44.0) (P<0.001). In Asia, the percentage of VF and survival to discharge rates were lower (11% and 2%, respectively) than those in Europe (35% and 9%, respectively), North America (28% and 6%, respectively), or Australia (40% and 11%, respectively) (P<0.001, P<0.001).</AbstractText>OHCA incidence and outcome varies greatly around the globe. A better understanding of the variability is fundamental to improving OHCA prevention and resuscitation.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,276 | Hypokalemia during the cooling phase of therapeutic hypothermia and its impact on arrhythmogenesis. | Mild to moderate therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) as the presenting rhythm. This approach entails the management of physiological variables which fall outside the realm of conventional critical cardiac care. Management of serum potassium fluxes remains pivotal in the avoidance of lethal ventricular arrhythmia.</AbstractText>We retrospectively analyzed potassium variability with TH and performed correlative analysis of QT intervals and the incidence of ventricular arrhythmia.</AbstractText>We enrolled 94 sequential patients with OHCA, and serum potassium was followed intensively. The average initial potassium value was 3.9±0.7 mmol l(-1) and decreased to a nadir of 3.2±0.7 mmol l(-1) at 10 h after initiation of cooling (p<0.001). Eleven patients developed sustained polymorphic ventricular tachycardia (PVT) with eight of these occurring during the cooling phase. The corrected QT interval prolonged in relation to the development of hypothermia (p<0.001). Hypokalemia was significantly associated with the development of PVT (p=0.002), with this arrhythmia being most likely to develop in patients with serum potassium values of less than 2.5 mmol l(-1) (p=0.002). Rebound hyperkalemia did not reach concerning levels (maximum 4.26±0.8 mmol l(-1) at 40 h) and was not associated with the occurrence of ventricular arrhythmia. Furthermore, repletion of serum potassium did not correlate with the development of ventricular arrhythmia.</AbstractText>Therapeutic hypothermia is associated with a significant decline in serum potassium during cooling. Hypothermic core temperatures do not appear to protect against ventricular arrhythmia in the context of severe hypokalemia and cautious supplementation to maintain potassium at 3.0 mmol l(-1) appears to be both safe and effective.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,277 | Cardiac herniation following completion pneumonectomy for bronchiectasis. | Sporadic reports on cardiac herniation are available in the literature; most of them had followed intrapericardial pneumonectomies for malignant pulmonary tumors. We present an uncommon event of heart herniation after a completion pneumonectomy indicated for chronic bronchiectasis. A 35-year-old male patient was operated for left completion pneumonectomy. A 6 cm x 4 cm area of adherent pericardium near the obtuse margin of heart was removed during surgery. During head-end elevation of the bed in postoperative intensive care unit, patient got accidentally tilted to the left side, which resulted in ventricular fibrillation. Chest cavity was re-opened for cardiopulmonary resuscitation. Left ventricle was found herniating through the pericardial deficiency into the left-thoracic cavity with the cardiac apex touching chest wall. During surgical re-exploration, the pericardial deficiency was closed with a synthetic Dacron patch. Hemodynamic condition remained stable in the immediate postoperative period. Patients had infection of the left thoracic cavity after 5 weeks, for which he was subjected to thoracoplasty and omentopexy. Prompt recognition with timely intervention is life saving from cardiac herniation. Strategy of closing the pericardial defect after pneumonectomy should be followed routinely, irrespective of the indication for pneumonectomy. |
5,278 | Therapeutic hypothermia following out-of-hospital cardiac arrest; does it start in the emergency department? | The use of therapeutic hypothermia after cardiac arrest is a well-practised treatment modality in the intensive care unit (ICU). However, recent evidence points to advantages in starting the cooling process as soon as possible after the return of spontaneous circulation (ROSC). There are no data on implementation of this treatment in the emergency department.</AbstractText>A telephone survey was conducted of the 233 emergency departments in the UK. The most senior available clinician was asked if, in cases where they have a patient with a ROSC after an out-of-hospital cardiac arrest, would therapeutic hypothermia be started in the emergency department.</AbstractText>Of the 233 hospitals called, 230 responded, of which 35% would start cooling in the emergency department. Of this 35%, over half (56%) said the decision to start cooling was made by the emergency physician before consultation with the ICU. Also, of the 35% who would begin cooling in the emergency department, 55% would cool only for ventricular fibrillation/ventricular tachycardia, 66% would monitor temperature centrally, and 14% would use specialised cooling equipment.</AbstractText>There is often a delay in getting patients to ICU from the emergency department, and thus the decision not to start cooling in the emergency department may impact significantly on patient outcome. The dissemination of these data may persuade emergency physicians that starting treatment in the emergency department is an appropriate and justifiable decision that is becoming a more accepted practice throughout the UK.</AbstractText> |
5,279 | Low-dose diltiazem in atrial fibrillation with rapid ventricular response. | Diltiazem is one of the most commonly used medications to control the rapid ventricular response in atrial fibrillation (AF). The recommended starting dose is an intravenous bolus of 0.25 mg/kg over 2 minutes. To avoid hypotension, we have empirically used a lower dose of diltiazem. We compared the efficacy and safety of different doses of diltiazem in rapid AF.</AbstractText>A retrospective chart review was undertaken in patients who presented to the emergency department with rapid AF. Patients were divided into 3 groups according to diltiazem dosage: low dose (≤ 0.2 mg/kg), standard dose (> 0.2 and ≤ 0.3 mg/kg), and high dose (> 0.3 mg/kg). We compared the rates of therapeutic response (adequate rate control) and complications (such as hypotension). Multivariate regression analysis was used to determine the effect of diltiazem dose on the occurrence of complications.</AbstractText>A total of 180 patients were included in the analysis. There were no significant differences in the rates of therapeutic response for the low-, standard-, and high-dose groups (70.5%, 77.1%, and 77.8%; P = .605). The rates of hypotension in the low-, standard-, and high-dose groups were 18%, 34.9%, and 41.7%, respectively. After adjusting confounding variables, the rate of hypotension was significantly lower in the low-dose group in comparison with the standard-dose group (adjusted odds ratio, 0.39; 95% confidence interval, 0.16-0.94).</AbstractText>Low-dose diltiazem might be as effective as the standard dose in controlling rapid AF and reduce the risk of hypotension.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,280 | Effects of norepinephrine on kidney in a swine model of cardiopulmonary resuscitation. | The aim of this study was to study the effects of norepinephrine (NE)-induced hypertension (HT) on renal biochemistry, enzymology, and morphology after restoration of spontaneous circulation (ROSC) by cardiopulmonary resuscitation (CPR) in swine.</AbstractText>After 4 minutes of ventricular fibrillation, standard CPR was carried out. The survivors were then divided into 2 groups. The HT group (n = 5) received 0.4 to 1.0 μg kg⁻¹ min⁻¹ of NE continuously to maintain the mean arterial pressure (MAP) at 130% of the baseline (ie, MAP before ventricular fibrillation). The normal pressure (NP) group (n = 5) received 0.2 to 0.5 μg kg⁻¹ min⁻¹ NE continuously to maintain MAP at the baseline level. Hemodynamic status and oxygen metabolism were monitored, and blood urea nitrogen and creatinine were measured in blood samples obtained at baseline and at 10 minutes, 2 and 4 hours after ROSC. At 24 hours after ROSC, the animals were killed and the kidney was removed to determine Na⁺-K⁺-ATPase and Ca²⁺-ATPase activities and histologic changes under a light and electron microscopy.</AbstractText>mean arterial pressure, cardiac output, and coronary perfusion pressure were significantly higher (P < .01), whereas the oxygen extraction ratio was lower in the HT group than in the NP group (P < .05). Blood urea nitrogen and creatinine increased in the NP group but did not change in the HT group. Renal ATP enzyme activity was significantly higher in the HT group than the NP group (Na⁺-K⁺-ATP enzyme: 4.024 ± 0.740 U versus 3.190 ± 0.789 U, Ca²⁺-ATP enzyme: 3.615 ± 0.668 versus 2.630 ± 0.816; both P < .05). The HT group showed less cellular edema, necrosis, and fewer damaged mitochondria compared with the NP group.</AbstractText>These data suggest that inducing HT by NE helps to maintain stable hemodynamic status and oxygen metabolism and may protect the kidney in terms of biochemistry, enzymology, and histology after CPR.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,281 | Abdominal compressions do not achieve similar survival rates compared with chest compressions: an experimental study. | The aim of this study is to investigate whether abdominal compression cardiopulmonary resuscitation (CPR) would result in similar survival rates and neurologic outcome than chest compression CPR in a swine model of cardiac arrest.</AbstractText>Forty Landrace/Large White piglets were randomized into 2 groups: group A (n = 20) was resuscitated using chest compression CPR, and group B (n = 20) was resuscitated with abdominal compression CPR. Ventricular fibrillation was induced with a pacemaker catheter, and animals were left untreated for 8 minutes. Abdominal and chest compressions were applied with a mechanical compressor. Defibrillation was then attempted.</AbstractText>Neuron-specific enolase and S-100 levels were significantly higher in group B. Ten animals survived for 24 hours in group A in contrast to only 3 animals in group B (P < .05). Neurologic alertness score was worse in group B compared with group A.</AbstractText>Abdominal compression CPR does not improve survival and neurologic outcome in this swine model of cardiac arrest and CPR.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,282 | Emergent precordial percussion revisited--pacing the heart in asystole. | Precordial percussion is a technique by which a manual force is applied repeatedly to the chest of a patient experiencing an unstable bradycardic or asystolic rhythm. The force is used not to defibrillate the myocardium as is the case with the "precordial thump" in pulseless ventricular tachycardia/ventricular fibrillation but rather to initiate a current through the myocardium in the form of an essentially mechanically paced beat. In this review, we discuss the physiology and utility of precordial percussion, or precordial thump, in the emergency setting as a very temporary bridge to more effective and permanent pacing techniques. |
5,283 | Radiofrequency energy induced ventricular fibrillation in a case of idiopathic premature ventricular contraction originating from the left ventricular papillary muscle. | A 15-year-old boy without structural heart disease was admitted for the treatment of frequent episodes of premature ventricular contractions (PVCs). Left ventricular mapping revealed that the origin of PVC was at the posterior papillary muscle. Diastolic small potentials were observed during sinus rhythm with a constant interval following QRS beats. This potential eventually coupled with the ventricular myocardium, resulting in the generation of PVC, and thus preceded QRS by 31 msec. Catheter ablation to this site induced non-sustained ventricular tachycardia, followed by transient ventricular fibrillation. Repeated application of radiofrequency energy eliminated PVC accompanied by the split of the diastolic potential. |
5,284 | Prophylactic implantable defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation or sustained ventricular tachycardia. | The role of implantable cardioverter-defibrillator (ICD) in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation (VF) or sustained ventricular tachycardia is an unsolved issue.</AbstractText>We studied 106 consecutive patients (62 men and 44 women; age, 35.6±18 years) with arrhythmogenic right ventricular cardiomyopathy/dysplasia who received an ICD based on 1 or more arrhythmic risk factors such as syncope, nonsustained ventricular tachycardia, familial sudden death, and inducibility at programmed ventricular stimulation. During follow-up of 58±35 months, 25 patients (24%) had appropriate ICD interventions and 17 (16%) had shocks for life-threatening VF or ventricular flutter. At 48 months, the actual survival rate was 100% compared with the VF/ventricular flutter-free survival rate of 77% (log-rank P=0.01). Syncope significantly predicted any appropriate ICD interventions (hazard ratio, 2.94; 95% confidence interval, 1.83 to 4.67; P=0.013) and shocks for VF/ventricular flutter (hazard ratio, 3.16; 95% confidence interval, 1.39 to 5.63; P=0.005). The positive predictive value of programmed ventricular stimulation was 35% for any appropriate ICD intervention and 20% for shocks for VF/ventricular flutter, with a negative predictive value of 70% and 74%. None of the 27 asymptomatic patients with isolated familial sudden death had appropriate ICD therapy. Twenty patients (19%) had inappropriate ICD interventions, and 18 (17%) had device-related complications.</AbstractText>One fourth of patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior sustained ventricular tachycardia or VF had appropriate ICD interventions. Syncope was an important predictor of life-saving ICD intervention and is an indication for ICD. Prophylactic ICD may not be indicated in asymptomatic patients because of their low arrhythmic risk regardless of familial sudden death and programmed ventricular stimulation findings. Programmed ventricular stimulation had a low predictive accuracy for ICD therapy.</AbstractText> |
5,285 | Assessment of left atrial volume: a focus on echocardiographic methods and clinical implications. | Left atrial enlargement is an important predictor of cardiovascular events such as atrial fibrillation, stroke, heart failure and mortality. A number of methods of left atrial size assessment by echocardiography have been reported, from the simple antero-posterior diameter in the parasternal long axis view to the more complex ellipsoid, area-length and Simpson's method of estimating left atrial volume. These different methods of left atrial size assessment, their clinical implications and some common pitfalls are discussed in this review. |
5,286 | Gender difference of clinical characteristics in Chinese patients with spontaneous variant angina. | Spontaneous attack of variant angina (VA) is a unique component of coronary artery disease (CAD), and associated with severe cardiac events. However, no data are available regarding sex differences in Chinese patients with spontaneous attacks of VA. Accordingly, the present retrospective study was initiated to evaluate the Clinical characteristics of Chinese female patients with spontaneous attacks of VA.</AbstractText>From January 2003 to January 2008, a total of 209 patients were diagnosed to have had a spontaneous attack of VA at Fu Wai Hospital. Of them, 27 were female, and their clinical findings were collected and compared with male patients for aspects of risk factors, clinical features and angiographical findings.</AbstractText>Spontaneous attacks of VA was relatively uncommon in female (12.9%) compared with male patients. The female patients were less likely to have a history of smoking (14.8% vs. 79.7%, P < 0.001), more likely to have a family history of CAD (33.3% vs. 11.0%, P < 0.01), and to have had a greater incidence of ventricular fibrillation during attack (11.1% vs. 2.2%, P < 0.05). There were no significant differences in other characteristics between the two groups.</AbstractText>Chinese female patients who experienced a spontaneous attack of VA had the characteristics of less smoking history, more family history of CAD and higher occurrence of ventricular fibrillation than male patients.</AbstractText> |
5,287 | Nifekalant hydrochloride terminating sustained ventricular tachycardia accompanied with QT dispersion prolongation. | Ventricular tachycardia (VT) and ventricular fibrillation are the main reasons causing sudden cardiac death. This study aimed to investigate the effects of nifekalant hydrochloride (NIF) on QT dispersion (QTd) in treating VT.</AbstractText>A total of 16 consecutive patients suffered sustained VT was included and then randomly divided into two groups according to the administration duration of NIF. In long-time group (group L), patients were injected with NIF continuously for at least 12 hours after a bolus dose. The patients in short-time group (group S) were injected with NIF just for 1 hour.</AbstractText>There were 7 of all 10 episodes of VT which were terminated by NIF, including 4 episodes in group L were stopped over 1 hour after continuous infusion of NIF. One patient suffered from torsade de pointes. Electrocardiography analysis indicated that QTd was significantly decreased 12 hours after stopping of infusing NIF compared with that when VT stopped ((45.4 +/- 22.1) ms vs. (73.4 +/- 33.2) ms, P < 0.01), and the corrected QTd (QTcd) decreased too ((47.8 +/- 22.9) ms vs. (78.3 +/- 36.5) ms, P < 0.01). There was a positive correlation between the increase in QTd and dose of administrating NIF (P < 0.01), so was QTcd (P < 0.01).</AbstractText>More administration of NIF indicates higher terminating rate of VT and more QTd prolongation. However, the safety is acceptable if several important issues were noticed in using NIF, such as serum potassium concentration, stopping side-effect related agents, and carefully observing clinical responses.</AbstractText> |
5,288 | Characteristics and risk factors of cerebrovascular accidents after percutaneous coronary interventions in patients with history of stroke. | Percutaneous coronary intervention (PCI) is a well-established method for managing coronary diseases. However, the increasing use of PCI has led to an increased incidence of acute cerebrovascular accidents (CVA) related to PCI. In this study, we investigated the characteristics and risk factors of CVA after PCI in patients with known stroke history.</AbstractText>Between January 1, 2005 and March 1, 2009, 621 patients with a history of stroke underwent a total of 665 PCI procedures and were included in this retrospective study. Demographic and clinical characteristics, previous medications, procedures, neurologic deficits, location of lesion and in-hospital clinical outcomes of patients who developed a CVA after the cardiac catheterization laboratory visit and before discharge were reviewed.</AbstractText>Acute CVA was diagnosed in 53 (8.5%) patients during the operation or the perioperative period. Seventeen patients suffered from transient ischemic attack, thirty-four patients suffered from cerebral infarction and two patients suffered from cerebral hemorrhage. The risk factors for CVA after PCI in stroke patients were: admission with an acute coronary syndrome, use of an intra-aortic balloon pump, urgent or emergency procedures, diabetes mellitus, and poor left ventricular systolic function, arterial fibrillation, previous myocardial infarction, dyslipidemia, tobacco use, and no/irregular use of anti-platelet medications.</AbstractText>The incidence of CVA during and after PCI in patients with history of stroke is much higher than that in patients without history of stroke. Patients with atrial fibrillation, previous myocardial infarction, diabetes mellitus, dyslipidemia, tobacco use, and no or irregular use of anti-platelet medications were at higher risk for recurrent stroke. This study showed a strong association between acute coronary syndromes and in-hospital stroke after PCI.</AbstractText> |
5,289 | A case of commotio cordis caused by steering wheel injury. | We report a rare case of commotio cordis caused by traffic injury. The patient was a 60-year-old female driver who suffered severe steering wheel impact to the chest during a head-on collision in which her car overturned. She had no history of cardiac disease. Emergency medical services arrived at the scene within 12 minutes of the accident. Evidence of ventricular fibrillation led the paramedics to carry out immediate defibrillation with an automated external defibrillator. Restoration of spontaneous circulation was confirmed within 2 minutes, along with establishment of sinus rhythm and normal wave form on electrocardiography. The patient was transported to our hospital in an emergency helicopter. General examination revealed chest bruising, and computed tomography of the chest showed pulmonary contusions; there was no other evidence of critical injury. We performed endotracheal intubation, as the patient had consciousness disturbance, and then initiated hypothermic therapy in the intensive care unit. Meanwhile, the hemodynamics remained stable, and there was no recurrence of arrhythmia. On day 15, the patient's consciousness improved, and she was able to communicate. Two months later, she was transported to another hospital for rehabilitation. |
5,290 | Hypoxia causes connexin 43 internalization in neonatal rat ventricular myocytes. | Gap junctions produce low resistance pathways between cardiomyocytes and are major determinants of electrical conduction in the heart. Altered distribution and function of connexin 43 (Cx43), the major gap junctional protein in the ventricles, can slow conduction, and thus contribute to arrhythmogenesis in experimental models such as ischemic rat heart and pacing-induced atrial fibrillation. The mechanisms underlying reduced gap junctional density and conductance during ischemia may involve decreased Cx43 synthesis, increased degradation and/or Cx43 migration into areas which do not contribute to intercellular communication. To test more rigorously the hypothesis that hypoxia resulting from ischemia causes Cx43 internalization, we infected neonatal rat ventricular myocytes (NRVM) with a Cx43-GFP chimera, which enabled us to investigate by means of confocal microscopy the effect of hypoxia (1% O2 for 5 h) on Cx43 distribution in live cardiomyocytes. Importantly, this protocol permitted each culture to serve as its own control. To this end we used life confocal microscopy analysis to determine in the same pair of myocytes the effects of hypoxia on Cx43-GFP distribution at the gap junctional (GJ) and non-GJ areas. In support of this hypothesis, we found that compared to normoxia, 5 h of hypoxia reduced the Cx43-GFP signal at the GJ areas (defined as the border area) and caused a corresponding increase in the Cx43-GFP signal at the non-border areas, thus providing an additional explanation for the intercellular uncoupling during ischemic conditions. |
5,291 | An impaired renal function and advanced heart failure represent independent predictors of the incidence of malignant ventricular arrhythmias in patients with an implantable cardioverter/defibrillator for primary prevention. | Malignant ventricular arrhythmias and inappropriate therapies represent unsolved problems in patients with implantable cardioverter/defibrillator (ICD) for primary prevention. This study focuses on the incidence of such therapies and thereby seeks to identify new predictors of adverse events to enhance risk stratification.</AbstractText>Ninety-four consecutive patients with mild-to-moderate heart failure (NYHA II-III) and depressed left ventricular function (≤35%) were followed for 34 ± 20 months. Two hundred and ninety-one malignant ventricular arrhythmias were documented in 51 patients (54%). Eighteen patients (19%) received inappropriate ICD therapies (e.g. atrial fibrillation, sinus tachycardia, etc.). Patients with malignant arrhythmia (1.34 ± 0.44 vs. 1.16 ± 0.4 mg/dL, P = 0.017) and patients suffering from inappropriate ICD therapies (1.54 ± 0.48 vs. 1.2 ± 0.38 mg/dL; P = 0.007) revealed a significantly worse renal function before ICD implantation than participants without any therapy. An increased serum creatinine at baseline (2 vs. 1 mg/dL; odds ratio (OR) 3.96; P = 0.02; 95% CI: 1.2-13.04) and NHYA class III compared with II (OR: 2.96; P = 0.02; 95% CI: 1.16-7.48) represent strong and independent predictors for the occurrence of ventricular arrhythmias. Moreover, an impaired renal function is identified as an independent risk factor for inappropriate therapies (OR: 5.6; P = 0.004; 95% CI: 1.72-18.22).</AbstractText>An impaired renal function and advanced heart failure before ICD implantation for primary prevention are identified as independent predictors for the incidence of appropriate ICD interventions. With regard to current guidelines and economical aspects, patients suffering from an impaired renal function or advanced heart failure seem to benefit most from ICD therapy.</AbstractText> |
5,292 | Sex differences in cardiac injury after severe haemorrhage and ventricular fibrillation in pigs. | Experimental studies have shown sex differences in haemodynamic response and outcome after trauma and haemorrhagic shock. We recently reported that female sex protects against cerebral injury after exsanguination cardiac arrest (CA), independent of sexual effects of hormones. The current study examines if female sex is also cardioprotective.</AbstractText>In this study 21 sexually immature piglets (12 males and 9 females) were subjected to 5 min of haemorrhagic shock followed by 2 min of ventricular fibrillation and 8 min of cardiopulmonary resuscitation (CPR). Volume resuscitation was started during CPR with intravenous administration of 3 ml kg(-1) hypertonic saline-dextran (HSD) solution for 20 min. Sexually immature animals were used to differentiate innate sex differences from the effects of sexual hormones. Sex differences in haemodynamics, myocardial injury (troponin I), and short-term survival (3-h) were evaluated.</AbstractText>After resuscitation female animals had a higher blood pressure, lower heart rate, lower troponin I concentrations, and higher survival rate (100% and 63% in 3 h) despite comparable sex hormone levels.</AbstractText>After resuscitation from haemorrhage and circulatory arrest, haemodynamic parameters are better preserved and myocardial injury is smaller in female piglets. This difference in outcome is independent of sexual hormones.</AbstractText>Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
5,293 | Mutations in the cardiac L-type calcium channel associated with inherited J-wave syndromes and sudden cardiac death. | L-type calcium channel (LTCC) mutations have been associated with Brugada syndrome (BrS), short QT (SQT) syndrome, and Timothy syndrome (LQT8). Little is known about the extent to which LTCC mutations contribute to the J-wave syndromes associated with sudden cardiac death.</AbstractText>The purpose of this study was to identify mutations in the α1, β2, and α2δ subunits of LTCC (Ca(v)1.2) among 205 probands diagnosed with BrS, idiopathic ventricular fibrillation (IVF), and early repolarization syndrome (ERS). CACNA1C, CACNB2b, and CACNA2D1 genes of 162 probands with BrS and BrS+SQT, 19 with IVF, and 24 with ERS were screened by direct sequencing.</AbstractText><AbstractText Label="METHODS/RESULTS" NlmCategory="RESULTS">Overall, 23 distinct mutations were identified. A total of 12.3%, 5.2%, and 16% of BrS/BrS+SQT, IVF, and ERS probands displayed mutations in α1, β2, and α2δ subunits of LTCC, respectively. When rare polymorphisms were included, the yield increased to 17.9%, 21%, and 29.1% for BrS/BrS+SQT, IVF, and ERS probands, respectively. Functional expression of two CACNA1C mutations associated with BrS and BrS+SQT led to loss of function in calcium channel current. BrS probands displaying a normal QTc had additional variations known to prolong the QT interval.</AbstractText>The study results indicate that mutations in the LTCCs are detected in a high percentage of probands with J-wave syndromes associated with inherited cardiac arrhythmias, suggesting that genetic screening of Ca(v) genes may be a valuable diagnostic tool in identifying individuals at risk. These results are the first to identify CACNA2D1 as a novel BrS susceptibility gene and CACNA1C, CACNB2, and CACNA2D1 as possible novel ERS susceptibility genes.</AbstractText>Copyright © 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
5,294 | Implantable cardioverter defibrillator therapy for congenital long QT syndrome: a single-center experience. | Long QT syndrome's (LQTS) marked heterogeneity necessitates both evidence-based and individualized therapeutic approaches.</AbstractText>This study sought to analyze a single LQTS specialty center's experience regarding the relationship between risk factors and appropriate ventricular fibrillation (VF)-terminating therapies among LQTS patients treated with an implantable cardioverter-defibrillator (ICD).</AbstractText>An internal review board-approved, retrospective analysis of the electronic medical records of 459 patients with genetically confirmed LQTS including the 51 patients (14 LQT1, 22 LQT2, and 15 LQT3) who received an ICD from 2000 to 2010 was performed.</AbstractText>Twelve patients (24%, 4 LQT1, 8 LQT2) experienced an appropriate, VF-terminating therapy with an average follow-up of 7.3 years, including 7 of 17 LQT2 female patients but none of the 15 LQT3 patients. Conversely, 15 (29%) patients (8 LQT3) have experienced an inappropriate shock. Secondary prevention indications (P = .008), non-LQT3 genotype (P = .02), QTc ≥ 500 ms (P = .0008), documented syncope (P = .05), documented torsades de pointes (P = .003), and a negative family history (P = .0001) were most predictive of an appropriate therapy. Importantly, no LQT-related deaths have occurred among the 408 non-ICD-treated patients.</AbstractText>The vast majority of LQTS patients can be treated effectively without an ICD. Potentially life-saving therapies were rendered at a 5% to 6% per year rate among those selected for ICD therapy; similar inappropriate shock frequencies were also noted. Secondary prevention, genotype, and QTc predicted those most likely to receive appropriate therapy. Although the ICD implant frequency is greatest among LQT3 patients, the greatest "save" rate has occurred among LQT2 women, who were assessed to be at high risk.</AbstractText>Copyright © 2010. Published by Elsevier Inc.</CopyrightInformation> |
5,295 | Sequential algorithm for life threatening cardiac pathologies detection based on mean signal strength and EMD functions. | Ventricular tachycardia (VT) and ventricular fibrillation (VF) are the most serious cardiac arrhythmias that require quick and accurate detection to save lives. Automated external defibrillators (AEDs) have been developed to recognize these severe cardiac arrhythmias using complex algorithms inside it and determine if an electric shock should in fact be delivered to reset the cardiac rhythm and restore spontaneous circulation. Improving AED safety and efficacy by devising new algorithms which can more accurately distinguish shockable from non-shockable rhythms is a requirement of the present-day because of their uses in public places.</AbstractText>In this paper, we propose a sequential detection algorithm to separate these severe cardiac pathologies from other arrhythmias based on the mean absolute value of the signal, certain low-order intrinsic mode functions (IMFs) of the Empirical Mode Decomposition (EMD) analysis of the signal and a heart rate determination technique. First, we propose a direct waveform quantification based approach to separate VT plus VF from other arrhythmias. The quantification of the electrocardiographic waveforms is made by calculating the mean absolute value of the signal, called the mean signal strength. Then we use the IMFs, which have higher degree of similarity with the VF in comparison to VT, to separate VF from VTVF signals. At the last stage, a simple rate determination technique is used to calculate the heart rate of VT signals and the amplitude of the VF signals is measured to separate the coarse VF from VF. After these three stages of sequential detection procedure, we recognize the two components of shockable rhythms separately.</AbstractText>The efficacy of the proposed algorithm has been verified and compared with other existing algorithms, e.g., HILB 1, PSR 2, SPEC 3, TCI 4, Count 5, using the MIT-BIH Arrhythmia Database, Creighton University Ventricular Tachyarrhythmia Database and MIT-BIH Malignant Ventricular Arrhythmia Database. Four quality parameters (e.g., sensitivity, specificity, positive predictivity, and accuracy) were calculated to ascertain the quality of the proposed and other comparing algorithms. Comparative results have been presented on the identification of VTVF, VF and shockable rhythms (VF + VT above 180 bpm).</AbstractText>The results show significantly improved performance of the proposed EMD-based novel method as compared to other reported techniques in detecting the life threatening cardiac arrhythmias from a set of large databases.</AbstractText> |
5,296 | The use of transtelephonic loop recorders for the assessment of symptoms and arrhythmia recurrence after radiofrequency catheter ablation. | Radiofrequency catheter ablation (RFA) is an effective treatment of arrhythmias. However, patients often remain symptomatic after the procedure. We aimed to assess the arrhythmia recurrence after successful RFA in relation to patients' symptoms using transtelephonic loop recorders. Thirty-six consecutive patients (age 50 +/- 14 years, 17 males/19 females) were enrolled after successful RFA for atrioventricular (AV) nodal reentrant tachycardia (n = 21), AV reentrant tachycardia (n = 8), atrial tachycardia (n = 2), atrial fibrillation/flutter (n = 4), and ventricular tachycardia (n = 1). During 23 +/- 6 days of follow-up, 679 events were recorded, 246 of which were true arrhythmic events, mostly (56%) asymptomatic. The vast majority of these true arrhythmic events were due to trivial arrhythmias (extrasystoles or sinus tachycardia), equally distributed among symptomatic and asymptomatic episodes. Arrhythmia relapse was shown in four patients, who had a total of nine episodes, eight of which were symptomatic. No high degree AV block was detected. Overall, symptom recurrence had low sensitivity (44%) and high specificity (95%) for the detection of any arrhythmia, and high sensitivity (89%) but low specificity (58%) for the detection of relapse. In conclusion, transtelephonic monitoring was a useful tool for the assessment of symptoms after RFA and its use may be reserved for the most symptomatic patients to detect a relapse or to reassure them for the benign nature of their symptoms. |
5,297 | The atria: from morphology to function. | The fact that some atrial and ventricular disorders (e.g., atrial fibrillation and heart failure) have a structural basis and cause atrial myocardial remodeling has led to increasing attention being paid to the atrial chambers. Furthermore, the rapid development of mapping and ablative procedures as a means of diagnosing and treating supraventricular arrhythmias has generated considerable interest in atrial gross anatomy, histology and ultrastructure. The aim of this article is to provide a comprehensive overview of the structure of the left and right atria (at macroscopic, histological and ultrastructural level) in relation to their function. In addition to analyzing normal atria, we also discuss functional anatomy in the case of atrial fibrillation and heart failure. |
5,298 | Idiopathic ventricular fibrillation controlled successfully with phenytoin. | We describe a case of an individual with idiopathic ventricular fibrillation whose arrhythmias were successfully controlled with phenytoin therapy. |
5,299 | Bivalirudin use during radiofrequency catheter ablation procedures in two patients with a history of heparin-induced thrombocytopenia. | Current guidelines recommend using bivalirudin, a direct thrombin inhibitor,as a preferred alternative to unfractionated heparin in patients with heparin induced thrombocytopenia (HIT) for percutaneous coronary intervention, as well as for cardiac and vascular surgery. Anticoagulation during radiofrequency catheter ablation (RFA) procedures may be another potential use for bivalirudin in the setting of HIT. Radiofrequency catheter ablation procedures involving left atrial or left ventricular access are increasingly employed as a method to treat cardiac arrhythmias. Because stroke risk is a serious complication of RFA, anticoagulation is required during this procedure. We describe the first report, to our knowledge, of successful use of bivalirudin anticoagulation during RFA procedures in two patients with a history of clinically diagnosed HIT that precluded the use of unfractionated heparin or low-molecular-weight heparin. One of the patients underwent RFA for ventricular tachycardia, the other for pulmonary vein isolation for the treatment of atrial fibrillation. In both patients, bivalirudin was administered as a 0.75-mg/kg intravenous bolus, followed by a 1.75-mg/kg/hour infusion.Activated clotting time (ACT) was measured after the initial bolus in each patient. However, no dosage adjustment was made based on the ACT, and the infusion rate of bivalirudin remained fixed during the procedures. Both procedures were completed without any embolic events. No bleeding or clotting events were noted; one patient experienced minor access site oozing that was not felt to be clinically important. Bivalirudin is a therapeutic option for anticoagulation during left-sided catheter RFA procedures in patients with a history of HIT. |
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