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9,400 | On the optimal defibrillation waveform--how to reconcile theory and experiment? | Medical intervention by electrical current as applied to humans or animals may have tremendous therapeutic impact if delivered while being carefully controlled. Otherwise, the situation can be harmful in terms of injury or even become lethal. These consequences demand close inspection of all relevant biological and technical factors. Regarding methods to counter fibrillation of the heart substantial progress has been made, but defining a gold standard for the waveshape and energy delivery remains a serious challenge. The anticipated answer is not simply a range somewhere between a maximum and a minimum, but most likely an "intelligently" selected case-specific optimum, delicately positioned between effective and unsafe. Combining insight from theory with pertinent experimental findings may offer a clearer view on an unresolved issue that often points to a cross-road of life and death. |
9,401 | Ultrasonically actuated silicon microprobes for cardiac signal recording. | In this paper, we report on ultrasonically actuated silicon thin microprobes that successfully penetrated canine cardiac tissue in vitro, and recorded the electrophysiological signals from multiple sites simultaneously within the heart wall. The penetration force--maximum force encountered by the probe during penetration--is found to reduce with increasing ultrasonic driving voltage, on both excised canine right ventricular muscle and chicken breast muscle. The rate of force decrease varies with tissue type and microprobe dimension. With ultrasonic actuation, the silicon microprobes are inserted into isolated perfused canine heart without breakage or significant buckling, under 10Vpp actuating voltage. Recordings were obtained from isolated perfused canine heart during pacing, following the induction of ventricular tachycardia, and during the transition from ventricular tachycardia to ventricular fibrillation. Local conduction velocity of 0.60 +/- 0.03 m/s was observed from the multichannel recordings from the canine right ventricular wall under epicardial pacing. The application of the ultrasonic microprobes in cardiac electrophysiology study can provide information for reconstruction of electrical wave propagation within the heart, which is important to understanding the mechanisms of cardiac arrhythmias. |
9,402 | Computer modeling of ventricular rhythm during atrial fibrillation and ventricular pacing. | We propose a unified atrial fibrillation (AF)-ventricular pacing (VP) (AF-VP) model to demonstrate the effects of VP on the ventricular rhythm during atrial fibrillation AF. In this model, the AV junction (AVJ) is treated as a lumped structure characterized by refractoriness and automaticity. Bombarded by random AF impulses, the AVJ can also be invaded by the VP-induced retrograde wave. The model includes bidirectional conduction delays in the AVJ and ventricle. Both refractory period and conduction delay of the AVJ are dependent upon its recovery time. The electrotonic modulation by blocked impulses is also considered in the model. Our simulations show that, with proper parameter settings, the present model can account for most principal statistical properties of the RR intervals during AF. We further demonstrate that the AV conduction property and the ventricular rate in AF depend on both AF rate and the degree of electrotonic modulation in the AVJ. Finally, we show that multilevel interactions between AF and VP can generate various patterns of ventricular rhythm that are consistent with previous experimental observations. |
9,403 | Experimental verification of theoretical predictions concerning the optimum defibrillation waveform. | The efficacy of electrical therapy at terminating ventricular fibrillation is highly dependent on the waveform used. We present experimental results which test one theory for defibrillation waveform dependence. Forty-four defibrillation waveforms (22 monophasic, 22 biphasic) were designed according to the theoretical construct of Fishier (2000). The waveforms were then tested on 67 male guinea pigs (46 for monophasic, 21 for biphasic waveforms) using a custom designed defibrillator and 12-mm subcutaneous disc electrodes. There was considerable agreement between the theoretical and experimental results. For example, as predicted, the ascending exponential waveform of 1 ms proved to be the most effective (86.4%) monophasic waveform, where efficacy is the number of successful shocks divided by the total number delivered. In addition, the efficacy decrease with duration increase was accurately predicted by the model for monophasic waveforms. For biphasic waveforms, as predicted by the model, when the first phase was optimized, an increase in second phase duration caused an increase in defibrillation efficacy (10 of 11 tested duration pairs). We conclude that the theoretical framework adequately explains the mechanism by which the defibrillation waveform affects efficacy for monophasic waveforms and, in at least one aspect, biphasic waveforms. |
9,404 | [Double chamber right ventricle. About 3 cases]. | The double chambered right ventricle is a rare congenital abnormality. It creates an obstacle for the right ventricular ejection. The cardiac ultra sonography examination allows the diagnosis in most majority of cases. The angiography is performed in difficult cases. We report 3 cases of infundibular stenosis with normal interventricular septum. The diagnosis was suspected for the 3 cases by the constellation of clinical findings pointing to systolic murmur over the precordium, and the electrocardiography showing right ventricular hypertrophy. It is confirmed by the echocardiogram and the hemodynamic exploration with a trans stenotic gradient evaluated at 72,80 and 80mmHg. The 3 patients underwent surgery and had all good post operative follow up. These 3 observations allow us to recall the epidemiological, embryological, clinical and echocardiographic particularities of pure infundibular stenosis and to determin the adequate treatment and the prognosis. |
9,405 | [Left atrial size in patients with arterial hypertension]. | Left atrial size is increased in patients with arterial hypertension. Left atrial enlargement represents a risk factor of atrial fibrillation and stroke. Left atrial size depends on the effect of many other etiological factors, predominantly by body mass and the left ventricular mass.</AbstractText>The objective of the study was to investigate the frequency of the left atrial enlargement in patients with arterial hypertension, in obese patients with arterial hypertension and in patients with arterial hypertension and left ventricular hypertrophy. In addition, the aim was to investigate the influence of diastolic function parameters on the left atrial dimension.</AbstractText>The study included 93 patients with arterial hypertension (mean age of 46.9 +/- 9.7 years, 50.5% of males) and 33 healthy subjects (mean age 45.6 +/- 10.6 yrs., 40% of males) who consisted the control group. There was no statistical difference of the age and sex between patients and healthy persons. All patients were examined by the echocardiographic ultrasound device HP Sonos 2500 by three echosonographers.</AbstractText>The patients with arterial hypertension compared to the control group had significantly higher: body mass index (27.8 +/- 4.1 versus 24.3 +/- 3.0) (p<0.001), the left ventricular mass (249.7 +/- 79.1 versus 174.6 +/- 47.7) (p<0.001), the left ventricular mass index (122.2 +/- 34.3 versus 96.7 +/- 20.9) (p<0.001) and the left atrium (3.8 +/- 0.7 versus 3.3 +/- 0.5) (p<0.001). The frequency of the left atrial enlargement in patients with arterial hypertension was 44.1%. The frequency of the left atrial enlargement in patients with arterial hypertension and the left ventricular hypertrophy was 53.3%, and in obese patients with arterial hypertension was 58.3%. Left ventricular diastolic function parameters in patients with arterial hypertension in relation to control exhibited statistically significant differences: isovolumetric relaxation time (IVRT) was longer (193.2 +/- 37.8 versus 175.8 +/- 23.6) (p<0.001), deceleration time (DT) was longer (193.2 +/- 37.8 versus 175.8 +/- 23.6) (p<0.01) and peak early diastolic filling wave velocity / peak atrial diastolic filling wave velocity ratio (E/A ratio) was lower (1.0 +/- 0.3 versus 1.2 +/- 0.3) (p<0.01). The quotient of linear correlation of the left ventricular diastolic function parameters in patients with arterial hypertension with left atrial volume did not show any significant correlation.</AbstractText>The left atrial size was statistically bigger in patients with arterial hypertension in relation to healthy subjects. The biggest left atrial enlargement was in hypertensive patients with the left ventricular hypertrophy and obese hypertensive patients. Left ventricular diastolic function parameters in patients with arterial hypertension had no statistically significant influence on the left atrial size.</AbstractText> |
9,406 | Thyroid hormone and heart failure. | Thyroid hormone metabolic disarray has been identified as a risk factor for the progression of heart disease and the development of heart failure (HF). Both hyper- and hypothyroidism have been associated with a failing myocardium. Poor cardiac contractility and low cardiac output due to hyperthyroidism is a rare occurrence and is mostly seen in patients with preexisting heart disease. Referred to as a "rate related" phenomenon, hyperthyroid-induced sustained sinus tachycardia or atrial fibrillation may further reduce ventricular contractility. Increasingly, the hypothyroid state, and in particular a low triiodothyronine level, has been associated with a reduced cardiac performance and poor prognosis in HF, even in the presence of normal thyroid-stimulating hormone levels. Low thyroid hormone levels alter cardiac gene expression and increase systemic vascular resistance, both resulting in a reduction of cardiac contractility and cardiac output. This review summarizes current data on thyroid dysfunction and HF as well as the emerging implications of the "low triiodothyronine state." |
9,407 | Cardiac safety of formoterol 12 microg twice daily in patients with chronic obstructive pulmonary disease. | Some evidence suggests an increased risk of myocardial infarction and dysrhythmia events associated with beta(2)-agonist use in patients with chronic obstructive pulmonary disease (COPD). This prospective, multicenter, randomized, double-blind, placebo-controlled study compared the cardiac safety of formoterol and placebo in patients with COPD.</AbstractText>After a 3-14-day run-in, 204 patients were randomized to receive formoterol 12 microg dry powder inhalation or matching placebo twice daily for 8 weeks. Twenty four-hour continuous electrocardiography (Holter monitoring) was performed at screening and after 2 and 8 weeks of treatment.</AbstractText>Only a small number of patients met the predefined criteria for a proarrhythmic event (4 formoterol and 2 placebo patients). No patients had sustained postbaseline ventricular tachycardia events, postbaseline run of ventricular ectopic beats associated with relevant symptoms (e.g. hypotension, syncope), or an episode of ventricular flutter or fibrillation. Holter monitoring data were variable but showed no clinically meaningful differences between the formoterol and placebo groups, respectively, for variables such as (mean+/-SD at end of treatment): heart rate (80+/-8.6 vs. 80+/-10.6 bpm), number and rate of ventricular premature beats (total 732+/-2685.4 vs. 650+/-2090.6; rate 35+/-131.0 vs. 30+/-101.3 per h), ventricular tachycardia events (total 0.4+/-1.70 vs. 1.0+/-9.23; rate 0.02+/-0.082 vs. 0.05+/-0.479 per h), and supraventricular premature beats (total 504+/-1844.1 vs. 823+/-2961.8; rate 22+/-80.6 vs. 37+/-129.6 per h). Vital signs and electrocardiogram data, including corrected QT intervals (Bazett and Fridericia), were similar across treatment groups. The overall adverse event experience was similar in the formoterol (n=26 [27%]) and placebo (n=33 [31%]) groups. The most common adverse events, infections and respiratory events, were expected for this patient population. The incidence of cardiac adverse events was low (1 formoterol and 4 placebo patients).</AbstractText>The results of this study confirm the good cardiovascular safety profile of formoterol in patients with COPD.</AbstractText> |
9,408 | Total thyroidectomy in amiodarone-induced thyrotoxicosis. Preoperative, intraoperative and postoperative considerations. | A female patient was admitted to our Department for total thyroidectomy in amiodarone-induced thyrotoxicosis. The drug was prescribed for ventricular arrhythmia and atrial paroxysmal fibrillation in dilated cardiomyopathy due to chronic aortic regurgitation with left ventricular dysfunction (ejection fraction 35%; Class Functional NYHA III) and moderate-severe respiratory insufficiency. The cardiologist-anesthetist team has allowed to evaluate the surgical-cardiovascular-anesthesiologic risks and the balance between the improvement by the amiodarone administration for the arrhythmia, and the discontinuation of this treatment in order to prevent aggravation of the thyrotoxicosis. These hypotheses were subsequently discharged for the two reasons listed below: - several other antiarrhytmic drugs (that didn't show equivalent efficacy as amiodarone in preventing or converting such ventricular and atrial arrhythmias) may be proposed in the place of amiodarone. However, this could expose the patient to an arrhythmia; - a clear proof that the suspension of amiodarone can allow restoring normalization of the thyroid function doesn't exist. Therefore, the patient has been successfully submitted to the surgical intervention and in the follow-up we brought her back to a state of normalized thyroid function and cardiovascular conditions. In patients that cannot safely discontinue amiodarone or when medical therapy is ineffective in controlling thyrotoxicosis, thyroidectomy is the treatment of choice. |
9,409 | Emerging role of vasopressin. | Ionotropic agents are frequently used in vasodilatory shock like conditions of septic or nonseptic origin. Conventional catecholamines such as norepinephrine are used at a very high dose with possibility of adverse effects in many patients. One often encounters refractoriness to these drugs. Infusion of vasopressin (VP) which is detectable at inappropriately low level in advanced phase of septic shock might allow withdrawal of catecholamines, as it maintains adequate mean arterial pressure (MAP), improves urine output and leaves perfusion of vital organs unhindered. Vasopressin has been found to be superior to epinephrine in animal models and some human trials, especially in patients with resistant ventricular fibrillation (VF) while doing cardiopulmonary resuscitation (CPR). Analogues of VP have also been used for diuresis in patients of hepatorenal syndrome. |
9,410 | Brugada-type electrocardiographic changes in a febrile patient of african descent. | Brugada syndrome is an arrhythmic syndrome characterized by a pattern of right bundle branch block and an ST-segment elevation in the right precordial leads on the electrocardiogram. This type of electrocardiographic change is predominantly documented in Asian and white persons and almost never present in persons of African ancestry. Despite the well-known risk of sudden death in patients with Brugada syndrome, controversy exists concerning the management of asymptomatic patients with Brugada-type electrocardiographic patterns. The present report describes the case of a patient with a Brugada-type electrocardiographic pattern induced by his febrile condition. A favorable outcome was achieved with a conservative approach. |
9,411 | Anesthetic management of an AAI pacemaker patient with paroxysmal atrial fibrillation during colorectal surgery. | Perioperative management of patients with cardiac pacemakers may be challenging because of the increasing sophistication of these devices. We report a case of a patient with paroxysmal atrial fibrillation (PAF) and with a permanent AAIR (bipolar atrial-inhibited adaptive rate) pacemaker who suffered life-threatening episodes of arrhythmias during operation. The first episode was vagally induced PAF during bowel manipulation; the second, induced by the increased pacing threshold from the external electric cardioversion and hyperkalemia. Transcutaneous pacing provided cardiac pacing and stabilized the patient during the second episode. Thorough preoperative evaluation and prophylactic placement of temporary pacing or at least transcutaneous pacing are important for the avoidance and minimization of intraoperative complications in patients with sick sinus syndrome and with an AAI (atrial inhibited) pacemaker. |
9,412 | Acute subendocardial ischaemia leads to homogenous prolongation in ventricular repolarization. | Acute transmural ischaemia often shortens ventricular repolarization and increases repolarization dispersion, leading to life threatening ventricular arrhythmias in animal models and human subjects. Experimental studies and clinical observations have shown that acute subendocardial ischaemia rarely causes serious ventricular arrhythmia. We hypothesized that the different arrhythmia outcomes between transmural and subendocardial ischaemia are largely due to the homogenous prolongation in ventricular repolarization after acute subendocardial ischaemia. Further experimental studies on a subendocardial model are required to assess the changes in ventricular repolarization and its spatial dispersion, and to investigate the role of these changes in the pathogenesis of ventricular arrhythmias. These studies will facilitate our understanding on the mechanisms of life-threatening ventricular arrhythmias during acute myocardial ischaemia. |
9,413 | Effects of cocaine intoxication on the threshold for stun gun induction of ventricular fibrillation. | This study sought to assess cocaine's effects on Taser-induced ventricular fibrillation (VF) threshold in a pig model.</AbstractText>Stun guns are increasingly used by law enforcement officials to restrain violent subjects, who are frequently intoxicated with cocaine and other drugs of abuse. The interaction of cocaine and the stun gun on VF induction is unknown.</AbstractText>We tested five adult pigs using a custom device built to deliver multiples of standard neuromuscular incapacitating (NMI) discharge that matched the waveform of a commercially available electrical stun gun (Taser X-26, Taser International, Scottsdale, Arizona). The NMI discharges were applied in a step-up and step-down fashion at 5 body locations. End points included determination of maximum safe multiple, minimum VF-inducing multiple, and ventricular fibrillation threshold (VFT) before and after cocaine infusion.</AbstractText>Standard NMI discharges (x1) did not cause VF at any of the 5 locations before or after cocaine infusion. The maximum safe multiple, minimum VF-inducing multiple, and VFT of NMI application increased with increasing electrode distance from the heart. There was a 1.5- to 2-fold increase in these values at each position after cocaine infusion, suggesting decreased cardiac vulnerability for VF. Cocaine increased the required strength of NMI discharge that caused 2:1 or 3:1 ventricular capture ratios at all of the positions. No significant changes in creatine kinase-MB and troponin-I were seen.</AbstractText>Cocaine increased the VFT of NMI discharges at all dart locations tested and reduced cardiac vulnerability to VF. The application of cocaine increased the safety margin by 50% to 100% above the baseline safety margin.</AbstractText> |
9,414 | Cardiac electrophysiological consequences of neuromuscular incapacitating device discharges. | The purpose of this study was to evaluate the cardiac consequences of neuromuscular incapacitating device (NID)/stun gun discharge in an experimental model.</AbstractText>The large-voltage electrical discharges from NIDs have been suggested to pose a risk for triggering cardiac arrhythmias.</AbstractText>Intracardiac catheters and blood pressure transducers were inserted before the application of NID discharges in six anesthetized pigs. Two different commercially available models (NID-1 and NID-2), two different vectors of discharges (thoracic: parallel to the long axis of the heart on the chest wall, and nonthoracic: away from the chest, across the abdomen), and two different durations of discharge (5 and 15 s) were tested. The effect of simulated adrenergic stress using epinephrine was also evaluated.</AbstractText>We studied a total of 150 discharges to 6 pigs; 74 of these discharges resulted in stimulation of the myocardium, as documented by electrical capture (mean ventricular rate during stimulation and capture, 324 +/- 66 beats/min). Of the 94 thoracic discharges, 74 stimulated the myocardium, compared with none from 56 nonthoracic discharges (p < 0.0001). During 16 discharges with epinephrine, there were 13 episodes of stimulation of the myocardium, of which 1 induced ventricular fibrillation and 1 caused ventricular tachycardia. Thoracic discharges from NID-1 were more likely to stimulate the myocardium than those from NID-2 (98% vs. 54%, p = 0.0007).</AbstractText>In an experimental model, NID discharges across the chest can produce cardiac stimulation at high rates. This study suggests that NIDs may have cardiac risks that require further investigation in humans.</AbstractText> |
9,415 | Left atrial volume predicts the risk of atrial fibrillation after cardiac surgery: a prospective study. | This study sought to identify preoperative predictors of postoperative atrial fibrillation (POAF) among patients undergoing cardiac surgery.</AbstractText>Postoperative atrial fibrillation is frequent after cardiac surgery and is associated with increased morbidity, mortality, prolonged hospital stay, and increased costs. Left atrial volume (LAV), a marker of chronically elevated left ventricular filling pressure, is a predictor of atrial fibrillation (AF) in the nonsurgical setting.</AbstractText>A total of 205 patients (mean age 62 +/- 16 years; 35% women) undergoing cardiac surgery were prospectively enrolled. Clinical risk factors were obtained by detailed medical record review and patient interview. Preoperative transthoracic echocardiograms were performed for assessment of LAV, left ventricular ejection fraction, and diastolic function. Follow-up was complete. Detection of POAF was based on documentation of AF episodes by continuous telemetry throughout hospitalization.</AbstractText>Postoperative atrial fibrillation occurred in 84 patients (41.4%) at a median of 1.8 days after cardiac surgery. The LAV was significantly larger in patients in whom AF developed (49 +/- 14 ml/m2 vs. 39 +/- 16 ml/m2, p = 0.0001). Patients with LAV >32 ml/m2 had an almost five-fold increased risk of POAF, independently of age and clinical risk factors (adjusted hazard ratio 4.84, 95% confidence interval 1.93 to 12.17, p = 0.001). Age and LAV were the only independent predictors of POAF. The area under the receiver-operator characteristics curve to predict POAF was 0.729 for LAV and 0.768 for the combination of LAV and age (both p < 0.0001).</AbstractText>The LAV is a strong and independent predictor of POAF. Risk stratification using LAV and age enables clinicians to identify high-risk patients before cardiac surgery.</AbstractText> |
9,416 | Four-year efficacy of cardiac resynchronization therapy on exercise tolerance and disease progression: the importance of performing atrioventricular junction ablation in patients with atrial fibrillation. | The goal of this study was to investigate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with permanent atrial fibrillation (AF) and the role of atrioventricular junction (AVJ) ablation.</AbstractText>Cardiac resynchronization therapy has been proven effective in heart failure patients with sinus rhythm (SR). However, little is known about the effects of CRT in heart failure patients with permanent AF.</AbstractText>Efficacy of CRT on ventricular function, exercise performance, and reversal of maladaptive remodeling process was prospectively compared in 48 patients with permanent AF in whom ventricular rate was controlled by drugs, thus resulting in apparently adequate delivery of biventricular pacing (>85% of pacing time), and in 114 permanent AF patients, who had undergone AVJ ablation (100% of resynchronization therapy delivery). The clinical and echocardiographic long-term outcomes of both groups were compared with those of 511 SR patients treated with CRT.</AbstractText>Both SR and AF groups showed significant and sustained improvements of all assessed parameters (model p < 0.001 for all parameters). However, within the AF group, only patients who underwent ablation showed a significant increase of ejection fraction (p < 0.001), reverse remodeling effect (p < 0.001), and improved exercise tolerance (p < 0.001); no improvements were observed in AF patients who did not undergo ablation.</AbstractText>Heart failure patients with ventricular conduction disturbance and permanent AF treated with CRT showed large and sustained long-term (up to 4 year) improvements of left ventricular function and functional capacity, similar to patients in SR, only if AVJ ablation was performed.</AbstractText> |
9,417 | Mechanisms of the acute ischemia-induced arrhythmogenesis--a simulation study. | The underlying ionic mechanisms of ischemic-induced arrhythmia were studied by the computer simulation method. To approximate the real situation, ischemic cells were simulated by considering the three major component conditions of acute ischemia (elevated extracellular K(+) concentration, acidosis and anoxia) at the level of ionic currents and ionic concentrations, and a round ischemic zone was introduced into a homogeneous healthy sheet to avoid sharp angle of the ischemic tissue. The constructed models were solved using the operator splitting and adaptive time step methods, and the perturbation finite difference (PFD) scheme was first used to integrate the partial differential equations (PDEs) in the model. The numerical experiments showed that the action potential durations (APDs) of ischemic cells did not exhibited rate adaptation characteristic, resulting in flattening of the APD restitution curve. With reduction of sodium channel availability and long recovery of excitability, refractory period of the ischemic tissue was significantly prolonged, and could no longer be considered as same as APD. Slope of the conduction velocity (CV) restitution curve increased both in normal and ischemic region when pacing cycle length (PCL) was short, and refractory period dispersion increased with shortening of PCL as well. Therefore, dynamic changes of CV and dispersion of refractory period rather than APD were suggested to be the fundamental mechanisms of arrhythmia in regional ischemic myocardium. |
9,418 | Clinical experience with tiered atrial therapies and atrial arrhythmia prevention algorithms in a dual chamber cardioverter defibrillator. | The acceptance of atrial arrhythmia features in implantable cardioverter defibrillators (ICDs) will depend on their ability to appropriately discriminate atrial tachyarrhythmias/atrial fibrillation (AT/AF). This study tested the effectiveness of an atrial/ventricular ICD with advanced atrial detection and new algorithms designed to prevent atrial arrhythmias.</AbstractText>Ninety-five patients were implanted with a dual chamber ICD (Model 1900, Guidant Corporation, MN, USA) at 25 US centers. Ten patients received a coronary sinus (CS) lead allowing a defibrillation vector for AT/AF cardioversion. Follow-up was 12.2 months. The addition of new atrial features designed for detection, discrimination, and prevention of AT/AF had no adverse effect upon detection of induced ventricular fibrillation (VF) (mean detection time with new features ON was 2.22 seconds vs 2.19 seconds with features OFF). A total of 100% of the induced and spontaneous ventricular and atrial arrhythmias receiving shock therapy were reviewed as appropriate detection. Atrial shock conversion efficacy for spontaneous and induced AT/AF episodes was 83% and 96%, respectively (144 spontaneous, 162 induced episodes). A 3-month randomized crossover trial of atrial preventative pacing features did not result in adverse effects, but there was no clinical efficacy for prevention of AT/AF.</AbstractText>Enhanced atrial detection and discrimination features combined with tiered atrial therapies did not adversely impact the ability of the ICD (Model 1900) to appropriately detect and treat ventricular tachyarrhythmias.</AbstractText> |
9,419 | Incidence of atrial fibrillation in heart transplant patients: long-term follow-up. | The incidence of atrial fibrillation (AF) in heart transplant patients has not been well documented.</AbstractText>To determine the incidence of AF in a cohort of patients undergoing cardiac transplantation, clinical data were obtained from a prospectively collected database for all consecutive orthotopic heart transplantation (OHT) patients and for all consecutive coronary artery bypass graft (CABG) surgery patients between January 1984 and March 2004 at our institution. A cohort of 1,714 OHT patients and low-risk CABG (normal ejection fraction [EF] and no left ventricular hypertrophy [LVH]) patients were age- and sex-matched.</AbstractText>The average age in the two groups was 56 +/- 7 years with 87% male and 81% white race and body mass index (BMI) of 26 +/- 4. There were 3 cases of AF (0.3%) in the OHT group and 757 cases of AF (21%) in the low-risk CABG group. The strongest independent predictor of freedom from postoperative AF was having had a transplant (odds ratio [OR] 96, 95% confidence interval [CI] 13-720). The incidence of AF, atrial flutter (AFL), and supraventricular tachycardia (SVT) in OHT was 0.33, 2.8%, and 1.3%, respectively. Given that incidence of AF, AFL, and SVT in historical post-CABG population is 25%, 17%, and 4.3%, transplanted patients appear to have lower incidence of AF, AFL, and SVT than the reference population. Consistent with this, transplanted patients underwent few ablation procedures for atrial arrhythmias. Additionally, the three patients with AF had bicaval anastomoses suggesting the possibility of PACs originating in the donor superior vena cava (SVC) or IVC (inferior vena cava) initiating AF in these patients.</AbstractText>In a cohort study of transplant and low-risk CABG patients, the strongest independent predictor of freedom from AF is having undergone transplant surgery. One potential explanation for the markedly lower incidence of AF may be effective isolation of thoracic veins with documented cases retaining the native SVC.</AbstractText> |
9,420 | Role of shortened QTc dispersion in in-hospital cardiac events in patients undergoing percutaneous coronary intervention for acute coronary syndrome. | QT dispersion (QTD) refers to the difference between maximal and minimal QT values on the electrocardiogram (ECG). QTD values are calculated and corrected with Bazett's formula (corrected QTD = QTcD = QTD/square root of RR). QTcD increases in patients with acute coronary syndrome (ACS). Recovery of increased QTcD (shortened QTcD) develops after successful revascularization, but prolonged QTcD occurs in certain patients. The aim of this study is to ascertain the clinical significance between shortened and prolonged QTcD groups after percutaneous coronary intervention (PCI).</AbstractText>We retrospectively enrolled 128 patients with ACS who had received PCI. The values of QTcD were measured manually on 12-lead standard ECGs obtained within 3 days before and after PCI (pre-PCI QTcD and post-PCI QTcD). All the patients were divided into 2 groups. The shortened QTcD group was defined as those patients with a decrease in QTcD after PCI and the prolonged QTcD group as those with an increase in QTcD after PCI. The underlying diseases, various clinical classifications and some prognostic factors were taken into comparison and statistical analysis between these 2 groups.</AbstractText>The shortened QTcD group showed a significantly higher rate of in-hospital cardiac death (13% vs. 0%, p = 0.006) and a greater pre-PCI QTcD (100.8 +/- 39.5 vs. 61.3 +/- 24.1 ms, p < 0.001) than the prolonged QTcD group. There was a significantly greater pre-PCI QTcD in patients with cardiac death than those without cardiac death (111.6 +/- 38.3 vs. 83.3 +/- 38.3ms, p = 0.027). Furthermore, the patients with in-hospital cardiac death presented with a significantly more frequent occurrence of in-hospital ventricular arrhythmia, compared with those without cardiac death (30.0% vs. 4.0%, p = 0.014).</AbstractText>Among the patients with ACS undergoing PCI, directly divided into shortened and prolonged QTcD groups regardless of initial pre-PCI QTcD, the shortened QTcD group showed a higher occurrence of in-hospital cardiac death and a greater pre-PCI QTcD. Shortened QTcD might be 1 risk factor for in-hospital cardiac death.</AbstractText> |
9,421 | Cardiac lipoma in the ventricular septum--a case report. | We report a case of a cardiac lipoma in the interventricular septum complicated with mitral regurgitation and atrial fibrillation in a 74-year-old woman. Surgical excision of the tumor was performed with mitral annuloplasty and a Maze III procedure. She continues to do well 7 months postoperatively. |
9,422 | Combined atrial fibrillation ablation with mitral valve surgery. | The study aim was to evaluate the efficacy and outcome of radiofrequency (RF) atrial fibrillation (AF) ablation in patients undergoing mitral valve (MV) surgery.</AbstractText>Between March 2002 and December 2004, 61 patients (mean age 65.4 +/- 10 years) underwent isolated endo-left atrial AF ablation using a unipolar RF device (Cardioblate; Medtronic, USA) in conjunction with 34 MV repairs and 27 MV replacements. AF was paroxysmal in 13 patients (21%), and permanent in 48 (79%), with a mean duration of 3.6 +/- 3.5 years. The etiology was degenerative in 35 patients (57%), rheumatic in 17 (28%), and ischemic in nine (17%). All patients received amiodarone postoperatively.</AbstractText>No patients died during the study, and there were no thromboembolic complications. All patients had intraoperative conversion. Forty-one patients (67%) presented with postoperative relapse; definitive conversion was achieved in 34 (83%) cases within three months. The overall success rate was 75.4% at 14 +/- 8.8 months; success was greater in the MV repair group (85%) than in the MV replacement group (66.7%), though not significantly so (p = 0.09). Factors associated with definitive conversion included smaller left atrial size (p = 0.007), decreased left ventricular end-diastolic diameter (p = 0.04), and NYHA class I (p = 0.05). Age, AF duration and etiology were not associated with conversion, but associated coronary artery bypass grafting showed a strong trend towards significance (p = 0.07). In these patients, AF duration did not predict conversion to sinus rhythm.</AbstractText>Combined AF ablation with MV surgery is safe and effective. Although AF ablation seems more beneficial with MV repair, the success rate may vary significantly according to patient characteristics.</AbstractText> |
9,423 | Hypercholesterolemia abrogates an increased resistance of diabetic rat hearts to ischemia-reperfusion injury. | Both, diabetes mellitus (DM) and hypercholesterolemia (HCH) are known as risk factors of ischemic heart disease, however, the effects of experimental DM, as well as of HCH alone, on ischemia/reperfusion-induced myocardial injury are not unequivocal. We have previously demonstrated an enhanced resistance to ischemia-induced arrhythmias in rat hearts in the acute phase of DM. Our objectives were thus to extend our knowledge on how DM in combination with HCH, a model that is relevant to diabetic patients with altered lipid metabolism, may affect the size of myocardial infarction and susceptibility to arrhythmias. A combination of streptozotocin (STZ; 80 mg/kg, i.p.) and the fat-cholesterol diet (1% cholesterol, 1% coconut oil; FCHD) was used as a double-disease model mimicking DM and HCH simultaneosly occurring in humans. Following 5 days after STZ injection and FCHD leading to increased blood glucose and cholesterol levels, anesthetized open-chest diabetic, diabetic-hypercholesterolemic (DM-HCH) and age-matched control rats were subjected to 6-min ischemia (occlusion of LAD coronary artery) followed by 10 reperfusion to test susceptibility to ventricular arrhythmias in the in vivo experiments and to 30-min ischemia and subsequent 2-h reperfusion for the evaluation of the infarct size (IS) in the Langendorff-perfused hearts. The incidence of the most life-threatening ventricular arrhythmia, ventricular fibrillation, was significantly increased in the DM-HCH rats as compared with non-diabetic control animals (100% vs. 50%; p<0.05). Likewise, arrhythmia severity score (AS) was significantly higher in the DM-HCH rats than in the controls (4.9+/-0.2 vs. 3.5+/-0.5; p<0.05), but was not increased in the diabetic animals (AS 3.7+/-0.9; p>0.05 vs. controls). Diabetic hearts exhibited a reduced IS (15.1+/-3.0% of the area at risk vs. 37.6+/-2.8% in the control hearts; p<0.05), however, a combination of DM and HCH increased the size of myocardial infarction to that observed in the controls. In conclusion, HCH abrogates enhanced resistance to ischemia-reperfusion injury in the diabetic rat heart. |
9,424 | Hyperthyroidism: a secondary cause of isolated systolic hypertension. | Isolated systolic hypertension is the most common form of hypertension, especially among patients 50 years or older. What is not appreciated is that there are secondary causes of isolated systolic hypertension. Hyperthyroidism increases systolic blood pressure by decreasing systemic vascular resistance, increasing heart rate, and raising cardiac output. Potential cardiovascular consequences of hyperthyroidism include atrial arrhythmias (especially atrial fibrillation), pulmonary hypertension, left ventricular hypertrophy, and heart failure. The prevalence of hypertension is greater among hyperthyroid patients than euthyroid patients. Whether there is a blunted nocturnal decline in ambulatory blood pressure among hyperthyroid patients is more controversial. Treatment is associated with a reduction in systolic blood pressure, heart rate, and cardiac output. |
9,425 | Effect of first ventricular tachycardia cycle length on rate of ventricular arrhythmia recurrence in patients with implantable cardioverter-defibrillator. | Some controversies exist regarding the proper treatment of hemodynamically tolerated and slow ventricular tachycardia (VT). We intended to assess the effect of cycle length of first VT episode on total ventricular arrhythmia burden in a cohort of patients with implantable cardioverter-defibrillator (ICD).</AbstractText>Between March 2000 and March 2005, 195 patients underwent ICD implantation at our center. We included 158 patients (mean age, 58.3 +/- 12.9 years) with follow-up of 3 months or more in this study. Clinical, electrocardiographic, and ICD-stored data and electrograms were collected and analyzed.</AbstractText>During the follow-up of 16.7 +/- 10.6 months, 45 (28.5%) and 20 (12.6%) patients received first appropriate ICD therapy for VT and ventricular fibrillation, respectively. We divided the 45 patients with VT (based on the median value of VT cycle length) into 2 groups. Although patients with VT cycle length of less than 350 had higher total mean number of appropriate ICD therapy (25 vs 6.3, P = .023), during multivariate regression analysis, only left ventricular ejection fraction (EF) of less than 25% (P = .020) was correlated with total number of appropriate ICD therapy. First VT cycle length (P = .341), QRS duration (P = .126), age (P = .405), underlying heart disease (P = .310), indication of ICD implantation (P = .113), and sex (P = .886) have failed to predict the total burden of ventricular arrhythmia during the follow-up period.</AbstractText>After adjustment for left ventricular EF, initial VT cycle length per se did not confer a lower risk for subsequent ventricular arrhythmia recurrence compared with those with faster VT. Left ventricular EF of less than 25% was correlated with higher ventricular arrhythmia burden in patients with ICD.</AbstractText> |
9,426 | Safety of stress echocardiography (from the International Stress Echo Complication Registry). | The safety of any diagnostic test is a major issue in deciding its practicability and cost-effectiveness. The aim of this study was to evaluate the safety of various stress echocardiographic modalities in the "real world." From February 1998 to January 2004, a simple written questionnaire was distributed to echocardiography laboratories across the world known to perform stress echocardiography. The following categories of major complications (known to occur during stress testing) were indicated: sustained ventricular tachycardia (> 30 beats/min), ventricular fibrillation, myocardial infarction, third-degree atrioventricular block, severe hypotension requiring therapy, cardiac asystole, cardiac rupture, stroke, and death. Three hundred centers were polled, from which 71 co-investigators responded and reported on 85,997 patient examinations. Exercise was used in 26,295 cases, dobutamine in 35,103, and dipyridamole in 24,599 cases. Life-threatening events occurred in 86 cases: during exercise in 4 patients (event rate 1 in 6,574), during dobutamine infusion (small dose for viability and/or large dose for ischemia) in 63 patients (event rate 1 in 557), and during dipyridamole stress testing in 19 patients (event rate 1 in 1,294). Of the 86 patients with complications, 5 died during dobutamine stress testing (ventricular fibrillation, n = 2; cardiac rupture, n = 3) and 1 after dipyridamole testing (cardiogenic shock). In conclusion, stress echocardiography is a safe method in the real world, but serious complications may occur. Exercise seems safer than pharmacologic stress and dipyridamole safer than dobutamine, possibly because of preselection criteria. |
9,427 | Usefulness of N-terminal pro-B-type natriuretic peptide levels to predict exercise capacity in hypertrophic cardiomyopathy. | Most patients with hypertrophic cardiomyopathy (HC) have reduced maximal oxygen consumption (VO2max) during exercise. The degree of impairment is poorly predicted by the magnitude of hypertrophy, left ventricular (LV) outflow tract obstruction, and other conventional markers of disease severity. The aim of this study was to determine the usefulness of N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) as a marker of exercise performance in HC. Plasma NT-pro-BNP was measured in 171 consecutive patients (mean age 46 +/- 18 years) who underwent echocardiography and cardiopulmonary exercise testing. The mean log NT-pro-BNP was 2.79 +/- 0.5; log NT-pro-BNP levels were higher in women patients (p = 0.001) and patients with chest pain (p = 0.010), in New York Heart Association class > or = II (p = 0.009), with atrial fibrillation (p < 0.001), with systolic impairment (p = 0.025), and with LV outflow tract obstructions (p < 0.0001). NT-pro-BNP levels were also correlated with maximal wall thickness (r = 0.335, p < 0.0001), left atrial size (r = 0.206, p = 0.007), and the mitral Doppler E/A ratio (r = 0.197, p = 0.012). The mean percent VO2max achieved was 73.8 +/- 22.6%; percent VO2max was smaller in patients with systolic impairment (p = 0.044) and LV outflow tract obstructions (p = 0.025). There were inverse correlations between percent VO2max and NT-pro-BNP (r = -0.352, p = 0.001), LV end-systolic cavity size (r = -0.182, p = 0.031), and left atrial size (r = -0.251, p = 0.003). On multivariate analysis, only NT-pro-BNP was correlated with percent VO2max. A NT-pro-BNP level of 316 ng/L had 78% sensitivity and 44% specificity (area under the curve 0.616) for predicting percent VO2max < 80%. In conclusion, NT-pro-BNP levels correlate with peak oxygen consumption in HC and are more predictive of functional impairment than other conventional markers of disease severity. |
9,428 | Three-phase model of cardiac arrest: time-dependent benefit of bystander cardiopulmonary resuscitation. | Evidence has suggested that the pathophysiology of ventricular fibrillation cardiac arrest may consist of 3 time-sensitive phases: electrical, circulatory, and metabolic. We performed a retrospective cohort study of adults in a metropolitan county who had had witnessed ventricular fibrillation arrest before emergency medical services were undertaken to investigate this 3-phase model with regard to bystander cardiopulmonary resuscitation (CPR). We hypothesized that the survival benefit from bystander CPR depends on the collapse-to-shock interval, with the highest benefit occurring during the circulatory phase. The collapse-to-shock interval was a priori grouped into 4 categories: 1 to 5, 6 to 7, 8 to 10, and > or = 11 minutes. We used logistic regression analysis to assess whether the association between CPR and survival to hospital discharge depended on the collapse-to-shock interval category. Of the 2,193 events meeting the inclusion criteria, 67.0% had received bystander CPR. The average collapse-to-shock interval was 8.2 +/- 2.8 minutes. The survival rate was 33.4%. A higher likelihood of survival was associated with bystander CPR (odds ratio [OR] 1.41, 95% confidence interval [CI] 1.15 to 1.73) and a shorter collapse-to-shock interval (OR -1.84, 95% CI 1.62 to 2.10, for each additional SD of 2.8 minutes less) after adjustment. The beneficial association of CPR increased as the collapse-to-shock interval increased (p = 0.05 for interaction). The bystander CPR was associated with an OR of survival of 0.96 (95% CI 0.64 to 1.46) for a 1- to 5-minute collapse-to shock interval, OR of 1.25 (95% CI 1.00 to 1.58) for a 6- to 7-minute interval, OR of 1.62 (95% CI 1.25 to 2.11) for an 8- to 10-minute interval, and OR of 2.11 (95% CI 1.32 to 3.37) for an > or = 11-minute interval. The results of this investigation support a phased model of ventricular fibrillation arrest. The findings suggest that the transition from the electrical to circulatory phase may occur at about 5 minutes, and the circulatory phase may extend to 15 minutes. |
9,429 | Short-term cardiac memory and mother rotor fibrillation. | Short-term cardiac memory refers to the effects of pacing history on action potential duration (APD). Although the ionic mechanisms for short-term memory occurring over many heartbeats (also called APD accommodation) are poorly understood, they may have important effects on reentry and fibrillation. To explore this issue, we incorporated a generic memory current into the Phase I Luo and Rudy action potential model, which lacks short-term memory. The properties of this current were matched to simulate quantitatively human ventricular monophasic action potential accommodation. We show that, theoretically, short-term memory can resolve the paradox of how mother rotor fibrillation is initiated in heterogeneous tissue by physiological pacing. In simulated heterogeneous two-dimensional tissue and three-dimensional ventricles containing an inward rectifier K(+) current gradient, short-term memory could spontaneously convert multiple wavelet fibrillation to mother rotor fibrillation or to a mixture of both fibrillation types. This was due to progressive acceleration and stabilization of rotors as accumulation of memory shortened APD and flattened APD restitution slope nonuniformly throughout the tissue. |
9,430 | Pre-treatment with Irbesartan attenuates left atrial stunning after electrical cardioversion of atrial fibrillation. | Left atrial (LA) stunning, the transient impairment of LA function, is responsible for an increased thrombo-embolic risk after cardioversion of atrial fibrillation (AF). Angiotensin receptor blockers (ARBs) attenuate atrial remodelling in AF and could theoretically influence LA stunning. We studied the effect of Irbesartan on LA stunning.</AbstractText>We prospectively assigned 50 patients from the outpatient clinic undergoing electrical cardioversion for AF with duration of >4 weeks, into two matched groups: 25 patients were treated with Irbesartan (228+/-93 mg/day) for at least 2 weeks prior to cardioversion (Irbesartan group); 25 patients did not receive ARBs (control group). The groups did not differ concerning age (64+/-13 vs. 63+/-13 years, respectively), AF duration (20+/-18 vs. 20+/-19 weeks), underlying disease, LA diameter (46+/-7 vs. 47+/-9 mm), left ventricular dimensions, and ejection fraction (47.7+/-11.6 vs. 49.7+/-14.5%). We assessed LA appendage emptying velocities (LAAEV) and LA spontaneous echo contrast (LASEC) by transoesophageal echocardiography before and after cardioversion and at 2 weeks, and the A-wave by transthoracic echocardiography after cardioversion, at 2 and at 4 weeks. LA stunning was significantly attenuated in the Irbesartan group. The reduction of LAAEV immediately after cardioversion was significantly less in the Irbesartan group (LAAEV reduction of 9+/-49% from 28+/-9 cm/s before cardioversion to 25+/-13 cm/s immediately afterwards) than in the control group (reduction of 48+/-20% from 34+/-15 cm/s before cardioversion to 16+/-6 cm/s afterwards) (P = 0.048). New or increased LASEC occurred in eight patients (32%) in the Irbesartan vs. 16 patients (64%) in the control group (P = 0.046).</AbstractText>Irbesartan significantly attenuates LA stunning after electrical cardioversion of AF. Therefore, ARBs may represent an important pharmacological supplementation in patients being prepared for cardioversion.</AbstractText> |
9,431 | Effect of levosimendan and milrinone on regional myocardial ischemia/reperfusion-induced arrhythmias in dogs. | Phosphodiesterase inhibitors as inodilators in heart failure are associated with promotion of arrhythmias. Calcium sensitizers have been proposed for the treatment of severe decompensated heart failure. The effect of levosimendan, a calcium sensitizer, and milrinone, a phosphodiesterase inhibitor, on ventricular arrhythmias was compared in a model of acute regional myocardial ischemia and reperfusion. The left anterior descending coronary artery in dogs was occluded for 25 minutes, followed by reperfusion. The 2 drugs were administered in a hemodynamically equieffective dose (0.1 micromol/kg) 10 minutes before coronary occlusion. Levosimendan, but not milrinone, significantly attenuated the pronounced increase in the number of ventricular premature beats (-63%), tachycardia (-50%), fibrillation (-70%), and inhomogeneity of ventricular electrical activation. Levosimendan significantly improved the overall survival rate. Levosimendan has a more beneficial profile than milrinone regarding the development of ventricular arrhythmias during and after regional myocardial ischemia. |
9,432 | Comparison of pyrroloquinoline quinone and/or metoprolol on myocardial infarct size and mitochondrial damage in a rat model of ischemia/reperfusion injury. | The cardioprotective effectiveness of low-dose pyrroloquinoline quinone (PQQ, 3 mg/kg) was compared with metoprolol, a beta(1)-selective adrenoceptor antagonist. Rats underwent 30 minutes of left anterior descending coronary artery occlusion and 2 hours of reperfusion. Metoprolol and/or PQQ were given at the onset of reperfusion to mimic clinical treatment. Metoprolol and/or PQQ reduced infarct size and protected against ischemia-induced left ventricular dysfunction after 2 hours of reperfusion. Combined therapy augmented left ventricular developed pressure at the end of reperfusion. Metoprolol or PQQ alone enhanced mitochondrial respiratory ratios in ischemic and nonischemic myocardium. Although the PQQ/metoprolol combination therapy increased respiratory ratio values, the effects were small when compared with PQQ alone. Only PQQ decreased lipid peroxidation. Metoprolol and/or PQQ given at the onset of reperfusion reduce infarct size and improve cardiac function. Combination therapy further reduces infarct size. PQQ is superior to metoprolol in protecting mitochondria from ischemia/reperfusion oxidative damage. |
9,433 | [Structural-functional alterations in the heart affecting dynamics of transmitral blood flow during a hemodialysis session]. | To study dynamics of transmitral circulation (TMC) during a hemodialysis (HD) session in patients with chronic renal failure (CRF) regarding structural-functional alterations of the heart and baseline condition of the diastolic function of left ventricular (LV) myocardium.</AbstractText>Sixty one patients (34 females and 27 males, mean age 47 +/- 11 years) on programmed HD free of heart valvular disease, ischemic heart disease, acute myocardial infarction, atrial fibrillation. Before and after HD session the patients underwent echocardiography, including Doppler regime.</AbstractText>Normal LV geometry was detected in 3 (4.9%) patients, concentric remodeling - in 9 (14.8%), concentric LV hypertrophy (LVH) - in 37 (60.7%), excentric LVH - in 12 (19.7%) patients. The ejection fraction was under 45% in 5 (8.2%) patients. Diastolic dysfunction of LV myocardium was found in 42 (68.9%) patients, TMC characteristic of slow relaxation was registered most frequently (47.6%). A pseudonormal type of TMC was recorded in 16 (38.1%) patients. HD did not change TMC significantly in patients with normal diastolic function (before HD E peak velocity was 88.7 +/- 19.8 cm/s, after - 80.0 +/- 24.6 cm/s, p > 0.05). In patients with initially disturbed relaxation the velocity of early diastolic flow (Vp) (color M-mode Doppler) increased (before HD, Vp was 67.6 +/- 17.1 cm/s, after - 72.9 +/- 15.7 cm/s, p < 0.05), E/Vp reduced (before HDm E/Vp was 1.2 +/- 0.4, after 1.0 +/- 0.4, p < 0.05). The subgroup with initially pseudonormal TMC showed decreased velocity in the E peak (before HD - 103.4 +/- 13.5 cm/s, after - 76.8 +/- 24.0 cm/s, p < 0.001). In restrictive TMC this velocity also decreased - 129.0 +/- 17.8 cm/s and 108.8 +/- 14.7 cm/s, p < 0.05, respectively).</AbstractText>TMC alteration during a HD session depends more on initial type of diastolic dysfunction than on LV geometry. A HD session improves intracardiac hemodynamics in patients with pseudonormal TMC.</AbstractText> |
9,434 | Antitachycardia pacing for spontaneous rapid ventricular tachycardia in patients with prophylactic cardioverter-defibrillator therapy. | Antitachycardia pacing (ATP) has not routinely been used in patients who received implantable cardioverter defibrillators (ICDs) for primary prevention of sudden death. This study investigated the efficacy of empirical ATP to terminate rapid ventricular tachycardia (VT) in heart failure patients with prophylactic ICD therapy.</AbstractText>Ninety-three patients with a mean left ventricular ejection fraction of 22 +/- 7% (range: 9-35%) due to nonischemic or ischemic cardiomyopathy received prophylactic ICDs with empiric ATP. At least 2 ATP sequences with 6-pulse burst pacing trains at 81% of VT cycle length (CL) were programmed in one or two VT zones for CL below 335 +/- 23 ms and above 253 +/- 18 ms. Ventricular flutter and fibrillation (VF) with CL below 253 +/- 18 ms were treated in a separate VF zone with ICD shocks without preceding ATP attempts. During 38 +/- 27 months follow-up, 339 spontaneous ventricular tachyarrhythmias occurred in 36 of 93 study patients (39%). A total of 232 VT episodes, mean CL 293 +/- 22 ms, triggered ATP in 25 of 36 patients with ICD interventions (69%). ATP terminated 199 of 232 VT episodes (86%) with a mean CL of 294 +/- 23 ms in 23 of 25 patients (88%) who received ATP therapy. ATP failed to terminate or accelerated 33 of 232 VT episodes (14%) with a mean CL of 287 +/- 19 ms in 12 of 25 patients (48%) who received ATP therapy.</AbstractText>Painfree termination of rapid VT with empirical ATP is common in heart failure patients with prophylactic ICD therapy. The occasional inability of empiric ATP to terminate rapid VT in almost 50% of patients who receive ATP for rapid VT warrants restrictive ICD programming with regard to the number of ATP attempts in order to avoid syncope before VT termination occurs.</AbstractText> |
9,435 | Effects of angiotensin converting enzyme inhibitor and angiotensin II receptor blocker on ventricular defibrillation threshold. | Angiotensin converting enzyme (ACE) inhibitors and Angiotensin II (AII) receptor blockers have previously been shown to be beneficial in treating patients with not only hypertension but also with cardiovascular diseases. Therefore, such drugs may potentially be used in patients with an implantable cardioverter defibrillator (ICD) who show cardiac dysfunctions.</AbstractText>This study aimed to determine effects of short-term administration of the ACE inhibitor (CV-3317) and the AII receptor blocker (CV-11974, an active form of candesartan) on internal defibrillation threshold (DFT) in anesthetized canine hearts.</AbstractText>DFTs were evaluated using a "hot can" defibrillation lead system in: (a) seven dogs following three intravenous administrations of 20 cc saline; (b) 11 dogs that received intravenous CV-3317 doses of 1 mg/kg, 10 mg/kg, and 50 mg/kg; and in (c) 10 dogs that were intravenously given 0.1 mg/kg, 1 mg/kg, and 10 mg/kg CV-11974. DFTs were determined using a "down-up down-up" protocol.</AbstractText>Mean DFT delivered energies at baseline and following three consecutive intravenous saline injections were 16.4 +/- 9.3 J, 15.3 +/- 7.5 J, 15.9 +/- 7.1 J, and 15.5 +/- 5.6 J, respectively. Those at baseline and following 1 mg/kg, 10 mg/kg, and 50 mg/kg intravenous CV-3317 were 12.9 +/- 6.4 J, 12.2 +/- 6.4 J, 11.0 +/- 6.6 J, and 11.9 +/- 6.6 J, respectively. Similarly, those at baseline and after 0.1 mg/kg, 1 mg/kg, and 10 mg/kg CV-11974 were 13 +/- 6.6 J, 12.5 +/- 6 J, 12.9 +/- 5.8 J, and 13.2 +/- 6.6 J, respectively. There were no significant differences between DFT at baseline and the others in each treatment group.</AbstractText>Since an ACE inhibitor and an AII receptor blocker did not alter DFT, such drugs may be useful in ICD patients without a decrease in safety margins.</AbstractText> |
9,436 | Clinical study of amiodarone-associated torsade de pointes in Chinese people. | Amiodarone-associated torsade de pointes (Tdp) has been reported increasingly in China in recent years. In this study, we made clinical analysis of amiodarone-associated Tdp in Chinese people.</AbstractText>Two major Chinese medical databases were searched to identify articles published during the last 26 years that presented data on amiodarone-associated proarrhythmic events. The articles were divided into two categories: case reports and observational studies.</AbstractText>Fifty-two Chinese-language case reports with 98 patients and 2 patients registered in our hospital, total 100 patients about amiodarone-associated Tdp, were enrolled in the study. Amiodarone-associated Tdp occurred more frequently in females (68.0%, 68/100). The major primary disease of females was rheumatic heart disease (40.7%, 24/59), while that of males was coronary heart disease (45.8%, 11/24). In most patients, Tdp occurred repeatedly and terminated in 24-48 hours. Some Tdp worsen to ventricular fibrillation and caused 19 patients' death (mortality rate 21.8%, 19/87). Known predisposing factors to the development of Tdp, such as heart failure, hypokalemia, drugs combination, and bradyarrhythmia, existed in many cases. Tdp also occurred in six patients (4 females, 2 males) without any known predisposing factors except QTc interval prolongation. Fourteen observational studies each reported data from at least 100 patients who were treated with amiodarone for at least 1 month. Of 2,354 patients included in these studies, 455 patients exposed to amiodarone were reported to have proarrhythmic events (an overall incidence of 19.3%), while only 4 patients were reported to have Tdp or ventricular fibrillation (an incidence of 0.17%).</AbstractText>In conclusion, approximately one-fifth of the patients have amiodarone-induced proarrhythmic events, while the incidence of Tdp or ventricular fibrillation is remarkably low. Amiodarone-associated Tdp occurred more frequently in Chinese females. Known predisposing factors for occurrence of Tdp prevailed in Chinese patients. QTc interval prolongation may be an independent risk factor of amiodarone-associated Tdp.</AbstractText> |
9,437 | Reducing unnecessary right ventricular pacing with the managed ventricular pacing mode in patients with sinus node disease and AV block. | Frequent and unnecessary right ventricular apical pacing increases the risk of atrial fibrillation or congestive heart failure. We evaluated a new pacing algorithm, managed ventricular pacing (MVP) which automatically changes modes between AAI/R and DDD/R in patients receiving pacemakers for symptomatic bradycardia.</AbstractText>Patients were randomized to the MVP mode or DDD/R mode for 1 month and then crossed over to the alternate pacing modality for an additional month. On completion of the crossover phase, the pacing mode selected was individualized and patients were followed for an additional 4 months.</AbstractText>Of the 129 patients who successfully completed the crossover study, the cumulative percent ventricular pacing was significantly reduced in the MVP mode (median 1.4%) compared to the DDD/R mode (median 89.6%, 94.0% relative reduction; 95% CI 89.3-98.8%, P < 0.001). Patients with sinus node disease (SND, n = 51) when compared to patients with AV block (AVB) (n = 68) experienced a greater reduction in ventricular pacing with the MVP mode compared to the DDD/R mode (median relative reduction 99.1%; 95% CI 97.5-99.9% vs median relative reduction 60.1%; 95% CI 16.7-93.9% P < 0.001). The reduced percent ventricular pacing during MVP was sustained over longer term follow-up.</AbstractText>The majority of patients with a bradycardia indication for cardiac pacing do not require ventricular pacing most of the time. The MVP mode significantly reduces unnecessary right ventricular pacing. This mode benefits even patients with intermittent AVB and is sustained over longer term follow-up.</AbstractText> |
9,438 | Safety of AngioJet thrombectomy in acute ST-segment elevation myocardial infarction: a large, single-center experience. | To determine the clinical outcomes associated with use of AngioJet thrombectomy (AT) during percutaneous coronary intervention (PCI) for acute ST-segment elevation myocardial infarction (STEMI).</AbstractText>Embolization of thrombus and atherosclerotic plaque is thought to contribute to sub-optimal myocardial reperfusion and worse clinical outcomes in STEMI. However, in a recent randomized trial, a higher mortality and infarct size was observed in patients treated with AT.</AbstractText>We performed a retrospective analysis of all patients who underwent primary or rescue PCI for STEMI between January 2000 and December 2005. Angiographic, procedural and in-hospital outcomes were compared between patients treated with or without AT.</AbstractText>1,260 STEMI patients underwent primary or rescue PCI at our hospital during the study period. Of these, 239 (19%) underwent adjunctive treatment with AT. Patients treated with AT were more likely to be female, smokers and have a right coronary artery culprit. A slightly lower incidence of thrombolysis in myocardial infarction (TIMI) 3 grade flow was observed in the AT group after PCI (86% vs. 90%, p = 0.04). There was no significant difference in the incidence of in-lab ventricular tachycardia/ventricular fibrillation, vascular complications or transfusion between the study groups. The peak creatine kinase was higher in patients treated with AT. The incidence of in-hospital major adverse cardiac events was 7.5% in the AT group and 9.0% in the control group (p = NS).</AbstractText>In this large, single-center experience, use of AT during mechanical reperfusion for STEMI was not associated with an increased risk of adverse outcomes. Our data suggest that AT may be performed safely in selected patients with STEMI.</AbstractText> |
9,439 | Pediatric defibrillation after cardiac arrest: initial response and outcome. | Shockable rhythms are rare in pediatric cardiac arrest and the results of defibrillation are uncertain. The objective of this study was to analyze the results of cardiopulmonary resuscitation that included defibrillation in children.</AbstractText>Forty-four out of 241 children (18.2%) who were resuscitated from inhospital or out-of-hospital cardiac arrest had been treated with manual defibrillation. Data were recorded according to the Utstein style. Outcome variables were a sustained return of spontaneous circulation (ROSC) and 1-year survival. Characteristics of patients and of resuscitation were evaluated.</AbstractText>Cardiac disease was the major cause of arrest in this group. Ventricular fibrillation (VF) or pulseless ventricular tachycardia (PVT) was the first documented electrocardiogram rhythm in 19 patients (43.2%). A shockable rhythm developed during resuscitation in 25 patients (56.8%). The first shock (dose, 2 J/kg) terminated VF or PVT in eight patients (18.1%). Seventeen children (38.6%) needed more than three shocks to solve VF or PVT. ROSC was achieved in 28 cases (63.6%) and it was sustained in 19 patients (43.2%). Only three patients (6.8%), however, survived at 1-year follow-up. Children with VF or PVT as the first documented rhythm had better ROSC, better initial survival and better final survival than children with subsequent VF or PVT. Children who survived were older than the finally dead patients. No significant differences in response rate were observed when first and second shocks were compared. The survival rate was higher in patients treated with a second shock dose of 2 J/kg than in those who received higher doses. Outcome was not related to the cause or the location of arrest. The survival rate was inversely related to the duration of cardiopulmonary resuscitation.</AbstractText>Defibrillation is necessary in 18% of children who suffer cardiac arrest. Termination of VF or PVT after the first defibrillation dose is achieved in a low percentage of cases. Despite a sustained ROSC being obtained in more than one-third of cases, the final survival remains low. The outcome is very poor when a shockable rhythm develops during resuscitation efforts. New studies are needed to ascertain whether the new international guidelines will contribute to improve the outcome of pediatric cardiac arrest.</AbstractText> |
9,440 | Alcohol septal ablation for hypertrophic obstructive cardiomyopathy: a systematic review of published studies. | Alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM) has emerged as a lesser invasive alternative to surgical myectomy over the past decade. The purpose of this study is to analyze all the published literature on outcomes and complications after ASA.</AbstractText>MEDLINE and PubMed were searched for all available published literature on ASA (June 1996-June 2005) using the terms hypertrophic obstructive cardiomyopathy (HOCM), alcohol septal ablation for hypertrophic obstructive cardiomyopathy, alcohol septal ablation for HOCM, alcohol septal ablation (ASA), transcoronary alcohol septal ablation for hypertrophic obstructive cardiomyopathy (TASH), transcoronary alcohol septal ablation for HOCM, nonsurgical septal reduction therapy (NSRT), and percutaneous transcoronary septal myocardial ablation (PTSMA).</AbstractText>A total of 42 published studies (2,959 patients) were analyzed. Mean age was 53.5 (35.4-72) years with a mean male to female ratio of 1.17. Mean follow-up was 12.7 +/- 0.3 months (1.5-43.2). Absolute ethanol (3 mL) was injected in 1.2 septal perforator arteries. On average, serum CK peaked at 964 units. At 12 months, there was a sustained decrease in resting and provoked LVOT gradient (65.3-15.8 and 125.4-31.5 mmHg, respectively) accompanied by reduction in basal septal diameter (20.9-13.9 mm), improvement in NYHA Class (2.9-1.2), and increase in exercise capacity (325.3-437.5 seconds). Early mortality (within 30 days) was 1.5% (0.0-5.0%) and late mortality (beyond 30 days) was 0.5% (0.0-9.3%). Other complications include ventricular fibrillation (2.2%), LAD dissection (1.8%), complete heart block requiring permanent pacemaker (10.5%), and pericardial effusion (0.6%). A repeat ASA was performed on 6.6% of patients and 1.9% of patients underwent surgical myomectomy with resolution of symptoms.</AbstractText>Literature to date suggests that ASA results in acute and intermediate-term favorable clinical and echocardiographic outcomes. A randomized controlled trial is needed to compare ASA and myomectomy in order to determine which technique provides maximal benefit.</AbstractText> |
9,441 | Evidence for multiple mechanisms in human ventricular fibrillation. | The mechanisms that sustain ventricular fibrillation (VF) in the human heart remain unclear. Experimental models have demonstrated either a periodic source (mother rotor) or multiple wavelets as the mechanism underlying VF. The aim of this study was to map electrical activity from the entire ventricular epicardium of human hearts to establish the relative roles of these mechanisms in sustaining early human VF.</AbstractText>In 10 patients undergoing cardiac surgery, VF was induced by burst pacing, and 20 to 40 seconds of epicardial activity was sampled (1 kHz) with a sock containing 256 unipolar contact electrodes connected to a UnEmap system. Signals were interpolated from the electrode sites to a fine regular grid (100x100 points), and dominant frequencies (DFs) were calculated with a fast Fourier transform with a moving 4096-ms window (10-ms increments). Epicardial phase was calculated at each grid point with the Hilbert transform, and phase singularities and activation wavefronts were identified at 10-ms intervals. Early human VF was sustained by large coherent wavefronts punctuated by periods of disorganized wavelet behavior. The initial fitted DF intercept was 5.11 +/- 0.25 (mean +/- SE) Hz (P < 0.0001), and DF increased at a rate of 0.018 +/- 0.005 Hz/s (P < 0.01) during VF, whereas combinations of homogeneous, heterogeneous, static, and mobile DF domains were observed for each of the patients. Epicardial reentry was present in all fibrillating hearts, typically with low numbers of phase singularities. In some cases, persistent phase singularities interacted with multiple complex wavelets; in other cases, VF was driven at times by a single reentrant wave that swept the entire epicardium for several cycles.</AbstractText>Our data support both the mother rotor and multiple wavelet mechanisms of VF, which do not appear to be mutually exclusive in the human heart.</AbstractText> |
9,442 | Ventricular fibrillation during no-flow global ischemia in isolated rabbit hearts. | The dominant frequency (DF) during ventricular fibrillation (VF) in Langendorff-perfused guinea pig hearts is higher in left ventricle (LV) than in right ventricle (RV). However, the onset of VF invariably leads to global ischemia. Whether or not a high DF source exists in LV during global ischemia is unknown.</AbstractText>By using a two-camera optical mapping system, epicardial activation patterns of VF were studied in 12 isolated rabbit hearts during baseline, no-flow global ischemia, and reperfusion. Simultaneous endocardial electrode recording was performed in 4 of the 12 hearts. Optical mapping showed type 1 VF at baseline, with multiple wandering and short-lived wavelets. After the onset of global ischemia, VF showed progressively increased spatiotemporal periodicity. The majority (65%) of VF recorded after 7 minutes of global ischemia showed type 2 VF, containing a single epicardial site with stable (> or = 3.85 seconds in duration) repetitive activities. Among the 33 sites with these activities, 24 were located near the interventricular septum, and 27 showed an epicardial breakthrough pattern with centrifugal propagation and wavebreaks distant from the focal site. After 10 minutes of global ischemia, the DF was lower on LV epicardium (5.0 +/- 1.4 Hz) than on RV epicardium (8.6 +/- 2.5 Hz, P < 0.001). However, there was no DF gradient between RV and LV endocardium (9.7 +/- 1.0 vs 9.6 +/- 0.9 Hz).</AbstractText>VF during prolonged global ischemia is consistent with type 2 VF with a single subepicardial source of rapid activation, mostly near the interventricular septum. The DF in LV is not higher than in RV.</AbstractText> |
9,443 | Pharmacologic management of cardiac emergencies. | When a person experiences arrhythmia (i.e., cessation of effective heart contractions), he or she can lose a pulse and become unconscious. Urgent medical care then is needed to improve outcomes and prevent sudden cardiac death. This care should include an electrocardiogram to identify the underlying arrhythmia and guide treatment. It is important for healthcare professionals to understand the role of medications in the treatment of potentially fatal arrhythmias. They should be familiar with the treatment algorithms for cardiac emergencies (as published by the American Heart Association) such as ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity, asystole, and severe bradycardia. A quick response with appropriate medical care will increase a patient's chance of survival. |
9,444 | Tachycardiomyopathy with familial predisposition masquerading as peripartum cardiomyopathy. | A 28-year-old pregnant lady presented with cardiomyopathy and atrial tachycardia. The patient had severe heart failure and syncope. Her past medical history was uneventful. Her mother, however, had received an implantable cardioverter defibrillator (ICD) after an out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation. The patient was scheduled for programmed stimulation, during which a monomorphic ventricular tachycardia was induced. An ICD was then implanted. Following radiofrequency ablation of the atrial tachycardia, left ventricular function recovered completely. Given the family history, a genetic predisposition to both arrhythmias and tachycardiomyopathy needs to be considered. |
9,445 | Intracoronary nicorandil prior to reperfusion in acute myocardial infarction. | A prospective, randomised, single centre study was designed to test the safety and efficacy of nicorandil infusion, a potassium channel opener, prior to reperfusion in ST-elevation acute myocardial infarction (STEMI).</AbstractText>Seventy STEMI patients with TIMI 0 to 2 flow were randomly assigned to nicorandil (Group N; n = 35) or control (Group C; n = 35) and underwent direct percutaneous coronary intervention (PCI). In Group N, 2 mg of nicorandil was infused directly into the infarct area prior to reperfusion. Incidence of anterior infarction was 60% in both groups. With nicorandil infusion, additional ST elevations without chest pain were observed for a few minutes in 94% of cases. However, no ventricular fibrillation or ventricular tachycardia occurred. TIMI myocardial perfusion grade 3 was significantly higher in Group N (40% vs. 17%, p<0.01). Patients were followed for up to 8 months, with similar incidence of major clinical adverse events, however left ventricular regional wall motion score significantly improved in Group N (P < 0.05). The effect of nicorandil was seen in patients without ischaemic preconditioning (P < 0.05).</AbstractText>This study suggests that direct infusion of nicorandil prior to revascularisation may be safe and beneficial.</AbstractText> |
9,446 | Fungal infection of implantable cardioverter-defibrillators: case series of five patients managed over 22 years. | With the increasing use of implantable cardioverter-defibrillators (ICDs), device complications are becoming more common. Fungal-related ICD infections have rarely been reported, and little is known about the presentation, prevalence, and treatment options for these morbid infections.</AbstractText>The purpose of this study was to characterize the clinical features, treatment, and outcomes of patients with fungal ICD infections.</AbstractText>We performed a retrospective review of ICD procedures performed at a single academic center and identified all ICD-related infections managed between 1983 and 2005.</AbstractText>Among a total of 3,648 ICD-related procedures performed between 1983 and 2005, we identified 47 (1.3%) cases of ICD infections, of which 5 (0.1%) were due to a fungal pathogen. Fungal infections were more likely to be associated with abdominal devices, to have a local rather than systemic infection, and to have a longer duration from the original implant to presentation. All patients were treated with ICD system explantation and antifungal therapy.</AbstractText>Fungal infection of ICDs is a rare but serious complication of device implantation that must be treated aggressively with complete hardware explantation and prolonged antifungal therapy. Because most infections are late complications and have indolent onsets, a high level of clinical suspicion is required for early diagnosis.</AbstractText> |
9,447 | Lipid-lowering drug use is associated with reduced prevalence of atrial fibrillation in patients with left ventricular systolic dysfunction. | Inflammation and oxidative stress have been implicated in the pathogenesis of atrial fibrillation (AF). Lipid-lowering drugs, particularly statins and fibrates, possess anti-inflammatory and antioxidant properties.</AbstractText>The purpose of this study was to assess the impact of lipid-lowering drug use on AF prevalence in patients with reduced left ventricular ejection fraction (LVEF).</AbstractText>Data were obtained from ADVANCENT(SM), a multicenter registry of patients with reduced LVEF (<or=40%). Demographic, clinical, and echocardiographic parameters were collected from interviews and medical records. Medications, including lipid-lowering drugs, were recorded.</AbstractText>Of the 25,268 patients, 71.3% had hyperlipidemia, and 66.8% were prescribed lipid-lowering drugs. AF prevalence was 25.1% in patients taking lipid-lowering drugs compared with 32.6% in untreated hyperlipidemic patients and 32.8% in patients without hyperlipidemia (P <.001 for both comparisons). In multivariable analysis, lipid-lowering drug use remained significantly associated with reduced odds of AF (odds ratio [OR] 0.69, 95% confidence interval [CI] 0.64-0.74), and this effect was larger than that of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (OR 0.85, 95% CI 0.79-0.92) or beta-blockers (OR 0.95, 95% CI 0.88-1.02). The beneficial impact of lipid-lowering drugs on AF risk was independent of their effects on the lipid profile. In patients in whom data on specific lipid-lowering drugs were available, 92% of the patients undergoing lipid-lowering therapy received statins, and 98% received statins and/or fibrates.</AbstractText>Use of lipid-lowering drugs in patients with reduced LVEF is associated with a significant reduction in the prevalence of AF independent of the lipid profile and other known arrhythmia risk factors. This effect is larger than that of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers or beta-blockers and may be the result of the antioxidant and anti-inflammatory effects of statins and fibrates.</AbstractText> |
9,448 | Validation of the noncontact mapping system in the left atrium during permanent atrial fibrillation and sinus rhythm. | The aim of this study was to validate noncontact mapping (NCM) in the left atrium (LA) during sinus rhythm and atrial fibrillation (AF).</AbstractText>Understanding the mechanisms of AF is crucial to the development of novel and effective treatments. Noncontact mapping records global electrical activation simultaneously and therefore has the potential to elucidate these mechanisms.</AbstractText>Patients underwent catheter ablation of permanent AF guided by NCM. Virtual and contact unipolar electrograms were recorded simultaneously during sinus rhythm and AF from sites spanning the LA and their morphology, amplitude, and timing were compared. The impact of distance from the array to the endocardial surface and electrogram amplitude were analyzed.</AbstractText>A total of 22 patients age 52 +/- 9 (mean +/- SD) years were studied. During sinus rhythm, the median (range) morphology correlation and timing difference between contact and virtual atrial electrograms were 0.81 (0.27 to 0.98) and 4.2 (0 to 18.3) ms, respectively. These results were significantly worse than the corresponding far field individual ventricular electrograms; 0.91 (0.53 to 1.0) and 1.7 (0 to 18.3) ms (p < 0.001). For endocardial sites >40 mm from the array, the correlation was significantly worse than sites <40 mm: 0.73 (0.48 to 0.95) versus 0.87 (0.27 to 0.98) (p < 0.001). The correlation during AF was 0.72 (0.24 to 0.98), which deteriorated with increasing distance from the array. In the presence of adenosine induced atrioventricular block the correlation deteriorated 0.67 +/- 0.16 versus 0.79 +/- 0.11 (p < 0.001).</AbstractText>Noncontact mapping can be performed in human LA; however, the accuracy of reconstructed electrograms is poor >40 mm from the center of the array, particularly during AF. Care must be taken interpreting isopotential maps if the entire endocardial surface of the LA is not close to the array.</AbstractText> |
9,449 | Dietary fish and n-3 fatty acid intake and cardiac electrocardiographic parameters in humans. | We evaluated the association between dietary fish intake and several cardiac electrocardiographic parameters in humans relevant to arrhythmic risk.</AbstractText>Fish consumption may reduce the incidence of sudden death and atrial fibrillation, possibly related to anti-arrhythmic effects.</AbstractText>In a population-based study of 5,096 men and women, we evaluated cross-sectional associations between usual dietary fish intake and electrocardiographic measures of heart rate, atrioventricular conduction (PR interval), ventricular repolarization (QT interval), and ventricular conduction (QRS interval). Multivariate models were adjusted for age, gender, race, education, smoking, body mass index, diabetes, coronary heart disease, physical activity, and intakes of beef or pork, fried fish, fruits, vegetables, alcohol, and total calories.</AbstractText>Consumption of tuna or other broiled or baked fish (comparing the highest to the lowest category of intake) was associated with lower heart rate (-3.2 beats/min, 95% confidence interval [CI] = 1.3 to 5.1; p trend <0.001), slower atrioventricular conduction (PR interval +7.2 ms, 95% CI = 1.4 to 12.9; p trend = 0.03), and substantially lower likelihood of prolonged QT (relative risk = 0.50, 95% CI = 0.27 to 0.95; p trend = 0.03). Tuna/other fish intake was not associated with ventricular conduction (p = 0.60). Findings were similar for estimated intake of marine n-3 fatty acids: a 1 g/day higher intake was associated with 2.3 beats/min lower heart rate (95% CI = 0.9 to 3.7), 7.6 ms longer PR interval (95% CI = 3.3 to 11.9), and 46% lower likelihood of prolonged QT (relative risk = 0.54, 95% CI = 0.33 to 0.88).</AbstractText>These findings in this large, population-based study suggest that dietary fish intake is associated with cardiac electrophysiology in humans, including heart rate, atrioventricular conduction, and ventricular repolarization, with potential implications for arrhythmic risk.</AbstractText> |
9,450 | Cumulative experience of azimilide-associated torsades de pointes ventricular tachycardia in the 19 clinical studies comprising the azimilide database. | The purpose of this study was to assess the incidence, temporal characteristics, and risk factors associated with azimilide-associated torsades de pointes (TdP) ventricular tachycardia.</AbstractText>Azimilide dihydrochloride is a class III antiarrhythmic drug possessing Ikr and Iks channel-blocking properties.</AbstractText>Oral azimilide (75 to 125 mg/day) was taken by 5,375 patients in 19 clinical trials conducted at 775 international centers. Of 3,964 patients in double-blind studies, 1,427 had a history of atrial fibrillation or other supraventricular arrhythmia, 510 had an implantable cardioverter-defibrillator, and 2,027 were post-myocardial infarction patients with a left ventricular ejection fraction < or =35%.</AbstractText>The TdP occurred in 56 patients assigned to azimilide, was dose-related, and tended to occur earlier with an azimilide-loading regimen. Forty-three percent of TdP patients had a QT interval corrected by Bazett's formula, for heart rate, (QTc) > or =500 ms at the time of or before the TdP occurrence. Significant risk factors using logistic regression were increasing age, female gender, diuretic use, and lack of aspirin use.</AbstractText>Azimilide-associated TdP has characteristics and risk factors similar to other Ikr blockers. However, there is a distinctive temporal profile. The TdP events are not concentrated in the first week. The azimilide-associated TdP rate is 1% (95% confidence interval 0.78 to 1.35) and is not increased in patients with low left ventricular ejection fraction, even in women.</AbstractText> |
9,451 | Recommendations for participation in leisure-time physical activity and competitive sports in patients with arrhythmias and potentially arrhythmogenic conditions Part I: Supraventricular arrhythmias and pacemakers. | This document by the Study Group on Sports Cardiology of the European Society of Cardiology extends on previous recommendations for sports participation for competitive athletes by also incorporating guidelines for those who want to perform recreational physical activity. For different supraventricular arrhythmias and arrhythmogenic conditions, a description of the relationship between the condition and physical activity is given, stressing how arrhythmias can be influenced by exertion or can be a reflection of the (patho)physiological cardiac adaptation to sports participation itself. The following topics are covered in this text: sinus bradycardia; atrioventricular nodal conduction disturbances; pacemakers; atrial premature beats; paroxysmal supraventricular tachycardia without pre-excitation; pre-excitation, asymptomatic or with associated arrhythmias (i.e. Wolff-Parkinson-White syndrome); atrial fibrillation; and atrial flutter. A related document discusses ventricular arrhythmias, channelopathies and implantable cardioverter defibrillators. |
9,452 | Atrial fibrillation post-cardiac surgery: changing perspectives. | Perioperative atrial fibrillation (AF) is one of the most frequent complications of cardiac surgery. Its development is associated with an increased morbidity and mortality, for example from perioperative stroke, as well as ventricular arrhythmias, postoperative myocardial infarction, congestive cardiac failure, renal failure, increased use of inotropic medications and the need for intra-aortic balloon pump. Furthermore, AF after cardiac surgery results in prolonged hospitalization after the procedure, as well as an excess utilization of hospital resources and increased hospital costs. Given the importance of AF for patient outcome, a wide variety of prophylactic pharmacologic strategies have been evaluated. The risk of post-operative AF should be reduced by the administration of amiodarone, a beta-blocker, sotalol or rate-limiting calcium antagonists. In addition, in patients undergoing cardiac surgery on pre-existing beta-blocker therapy, this treatment should be continued unless contraindications develop (such as post-operative bradycardia or hypotension). Unless contraindicated, a rhythm control strategy is recommended as the initial option for the treatment of post-operative AF following cardiothoracic surgery. More recently, some data regarding magnesium, statins and n-3 polyunsaturated fatty acids in reducing post-op AF are available. Clearly, perspectives are changing in our management of this common arrhythmia. |
9,453 | Assessment of T-wave alternans after acute myocardial infarction: influence of the timing of PTCA on cardiac electrical stabilization. | It is accepted that the timing of myocardial revascularization in patients undergoing PTCA for the treatment of acute myocardial infarction (AMI) may improve the clinical outcome. However, its impact on microvolt T-wave alternans (TWA), a recognized tool for assessing vulnerability to ventricular tachyarrhythmias that can cause sudden cardiac death in infarction survivors, remains unknown.</AbstractText>To analyze TWA in patients with AMI treated by PTCA and assess whether the timing of myocardial revascularization can influence TWA measurements.</AbstractText>We studied 79 patients (67 male; 57 +/- 11 years) who underwent successful PTCA for the treatment of AMI. The presence of TWA was assessed using a HearTwave system (Cambridge Heart, Inc.) within 30 days of AMI. Orthogonal Frank XYZ leads and associated vector magnitude (microvolt alternans sensors) and 7 standard ECG leads were recorded during a treadmill manual exercise protocol to increase heart rate slowly to approximately 110 bpm. TWA was considered positive if the sustained alternans microvoltage was > or = 1.9 microV at heart rates of > 100 bpm, negative if the criteria for positivity were not met while maintaining heart rate at > or =105 bpm (maximum negative heart rate), and inconclusive if it could not be definitively classified as either positive or negative. Patients were excluded if they had atrial fibrillation, > 10 extrasystoles/min, bradycardia 40 beats/min, wide QRS complex, congestive heart failure or implanted pacemaker, or were under antiarrhythmic therapy. The presence of positive or inconclusive TWA (non-negative TWA) was considered a risk marker for the occurrence of life-threatening ventricular arrhythmias. TWA results were compared between the group of patients who underwent PTCA within 24h of AMI (early PTCA; n=45) and those treated >24h after hospital admission (late PTCA; n=34).</AbstractText>TWA was positive in 16 patients (20.2%), negative in 56 (70.9%) and inconclusive in 7 (8.9%). Overall, TWA was non-negative in 29.1% of the patients. In the early PTCA group, TWA was non-negative in 9 patients (20%) (6 positive and 3 inconclusive) and negative in 36 (80%). In the late PTCA group, TWA was non-negative in 14 patients (41%) (10 positive and 4 inconclusive) and negative in 20 (59%) (p < 0.05). There were no differences in left ventricular ejection fraction between the two groups. No spontaneous ventricular arrhythmias, syncope or deaths were recorded in the first 60 days after hospital discharge. Five patients (7%) were re-admitted with angina.</AbstractText>In a population of AMI survivors: a) the prevalence of non-negative TWA was 25%, despite myocardial revascularization by PTCA; b) PTCA performed within 24h of onset of AMI significantly reduced the number of patients with non-negative TWA, suggesting a lower arrhythmic risk. These findings should be investigated in larger studies.</AbstractText> |
9,454 | Adenosine concentration in great cardiac vein is increased in non-ventricular fibrillation dogs. | This study was conducted to clarify the relationship between myocardial endogenous adenosine concentration in the great cardiac vein during ischemia and reperfusion-induced ventricular fibrillation (VF) and the occurrence rate of ischemia and reperfusion-induced VF. Sixty anesthetized mongrel dogs were subjected to 10-min left anterior descending artery occlusion and reperfusion. Blood from the great cardiac vein was sampled for the determination of adenosine and catecholamine concentrations. Hemodynamic parameters (blood pressure, lift ventricular dp/dt, left ventricular end-diastolic pressure, and cardiac output) were monitored throughout the experimental period. During coronary occlusion and reperfusion, VF occurred in 25 dogs (VF group). Ventricular fibrillation did not occur in 35 other dogs (non-VF group). Adenosine concentration in the great cardiac vein before the coronary occlusion did not differ between the two groups. However, the adenosine concentration in the great cardiac vein of the non-VF group significantly increased compared with that of the VF group (2,343 vs 65 pmol/ml, P = 0.026) during coronary occlusion and reperfusion. In contrast, hemodynamic parameters did not differ between the two groups. The study results demonstrated that adenosine concentration in the great cardiac vein was higher in the non-VF group than in the VF group, suggesting that myocardial endogenous adenosine may have a role in the suppression of ischemia and reperfusion-induced VF in dogs. |
9,455 | Amiodarone therapy in patients implanted with cardioverter-defibrillator for life-threatening ventricular arrhythmias. | Whether amiodarone can improve the patient's clinical outcome by reducing implantable cardioverter-defibrillator (ICD) therapy deliveries for ventricular tachycardia or fibrillation (VT/VF) has not been clearly evaluated.</AbstractText>A total of 507 patients with VT/VF due to organic heart disease who had ICDs implanted were enrolled in this study. The patients were divided into 3 groups: Amiodarone (n=247), Class I anti-arrhythmic drug (n=103) and CONTROL (n=157) groups, and the total cause mortality and arrhythmic event free survival rates were evaluated between the groups. The mean follow-up period was 38+/-27 months. The left ventricular ejection fraction was significantly decreased in the Amiodarone group (Amiodarone: 37+/-15%; Class I: 39+/-16%;</AbstractText>44+/-17%). The mortality and arrhythmic events were significantly higher in the Class I group than the Amiodarone group (p<0.05), but there was no significant difference between the Amiodarone and CONTROL groups (arrhythmic event free rate at 5 years: Amiodarone: 53%; Class I: 35%;</AbstractText>48%; 5 year survival: 86%, 74% and 77%, respectively). Side effects from amiodarone were found in 12% of the patients, but no fatal events were observed.</AbstractText>The present study could not demonstrate the benefit of amiodarone in ICD patients, probably due to a significant clinical bias exerted in selecting this drug.</AbstractText> |
9,456 | Biventricular stimulation to prevent cardiac desynchronization: rationale, design, and endpoints of the 'Biventricular Pacing for Atrioventricular Block to Prevent Cardiac Desynchronization (BioPace)' study. | Despite the deleterious effects of cardiac dyssynchrony and the positive effects of cardiac resynchronization therapy, patients with high-degree atrioventricular block continue to receive desynchronizing right ventricular (RV) pacing systems. Although it is unclear whether the negative effects of RV pacing and left bundle branch block (LBBB) are comparable, and whether they depend on the presence and the degree of structural heart disease, one may hypothesize that RV pacing may have similar effects to LBBB. In the BioPace trial, the long-term effects of RV pacing vs. biventricular pacing will be prospectively compared in 1200 pacemaker patients with high likelihood of mostly paced ventricular events, regardless of whether in sinus rhythm or in atrial fibrillation (AF). After echocardiographic examination of left ventricular (LV) function, patients will be randomly assigned to the implantation of an RV vs. a biventricular pacing system and followed for up to 5 years. Primary study endpoints are survival, quality of life (QoL), and the distance covered in a 6-min hall walk (6-MHW) at 24 months after implantation. Secondary endpoints are QoL and the 6-MHW result at 12 months after implantation, hospitalization rate, LV dimensions, LV ejection fraction, and the development of chronic AF and other adverse events. |
9,457 | Predictors of VT/VF-occurrence in ICD patients: results from the PROFIT-Study. | Identification of risk factors for ventricular tachycardia/ventricular fibrillation (VT/VF) occurrence in patients with implantable cardioverter-defibrillators (ICD) is reasonable, because ICD patients with multiple risk factors might benefit from more aggressive anti-arrhythmic therapy for the prevention of arrhythmic events. Furthermore, in the era of prophylactic ICD therapy and limited healthcare resources, additional markers are needed for improved patient selection.</AbstractText>Thus, in Prospective Analysis of Risk Factor for Appropriate ICD Therapy (PROFIT), we prospectively analyzed the role of ejection fraction (EF), N-terminal probrain natriuretic peptide (NT-proBNP), New York Heart Association (NYHA) class, atrial fibrillation, and QRS-duration as independent predictors for VT/VF occurrence in 250 ICD patients. Kaplan-Meier analysis showed that EF<40% (log-rank P=0.001), NT-proBNP levels higher than median (>or=405 ng/L; log-rank P=0.04), QRS-duration >or=150 ms (log-rank P=0.016), permanent atrial fibrillation (log-rank P=0.008), and higher NYHA class (log-rank P=0.029) were associated with VT/VF occurrence. By multivariate Cox regression analysis EF, QRS-duration and atrial fibrillation remained significantly associated with appropriate VT/VF therapy, whereas there was no relationship among NT-proBNP, NYHA class, and VT/VF occurrence. Stratifying patients according to the number of their independent risk factors (EF<40%, AF, QRS-width>or=150 ms) showed that patients with greater than or equal to two risk factors had a 100% 2-year risk of VT/VF occurrence, whereas patients with no or one risk factor had a 19.3 and 25% 2-year risk, respectively.</AbstractText>EF<40%, permanent atrial fibrillation, and QRS>or=150 ms are independent predictors for VT/VF occurrence in predominantly secondary prophylactic ICD patients. Combining all independent predictors, we developed a risk score for VT/VF occurrence identifying a subgroup of patients with two or more risk factors who had a 100% 2-year risk. Future studies will reveal if this risk score helps to identify ICD patients suitable for empirical anti-arrhythmic therapy and to improve patient selection for prophylactic ICD therapy.</AbstractText> |
9,458 | Idiopathic left ventricular aneurysm and sudden cardiac death in young adults. | We report three young patients presenting with life-threatening ventricular tachycardia (VT) or ventricular fibrillation (VF) and/or survived sudden cardiac arrest, who were admitted to our institution for further diagnostic evaluation.</AbstractText>In all patients, idiopathic left ventricular (LV) aneurysms were identified after a detailed non-invasive and invasive evaluation. Sustained VT/VF was inducible during programmed ventricular stimulation in two of the three patients. Left ventricular aneurysms were depicted and characterized by various imaging modalities (echocardiography, magnetic resonance imaging, LV angiography). To elucidate the pathogenesis further, both myocardial viability and regional sympathetic innervation were assessed by radionuclide imaging techniques. Defects of innervation and metabolism were documented in the area of the aneurysm but distal to the aneurysm there were no signs of downstream denervation.</AbstractText>Life-threatening arrhythmias may be the first manifestation of an idiopathic LV aneurysm, which can be reliably diagnosed with modern imaging techniques. Radionuclide imaging may yield additional information as to the involvement of the autonomic nervous system potentially associated with arrhythmogenesis. Management strategies in patients with an idiopathic LV aneurysm range from antiarrhythmic drug treatment, implantation of an automatic cardioverter-defibrillator to surgical aneurysmectomy.</AbstractText> |
9,459 | Atrial fibrillation predicts appropriate shocks in primary prevention implantable cardioverter-defibrillator patients. | Atrial fibrillation (AF) is often present in patients with left ventricular dysfunction who receive an implantable cardioverter-defibrillator (ICD). The purpose of this study was to investigate whether AF is associated with appropriate shocks and cardiovascular mortality in primary prevention ICD patients with left ventricular dysfunction.</AbstractText>We included 80 primary prevention ICD patients with left ventricular dysfunction and compared the outcome between patients with a history of AF (n=29) and patients with no history of AF (n=51). The primary endpoint was occurrence of appropriate shocks. Secondary endpoints were: (1) the composite of cardiovascular mortality/appropriate shocks; and (2) inappropriate shocks. During follow-up (median 8 months, range 1-60), patients with a history of AF more often received appropriate shocks than patients with no history of AF (24 vs. 6%, P=0.03). The composite endpoint of cardiovascular mortality/appropriate shocks was also more likely to occur in patients with a history of AF (34 vs. 12%, P=0.02). History of AF predicted appropriate shocks (HR 6.9, 95% CI 1.7-27.5, P=0.006) and the composite endpoint of cardiovascular mortality/appropriate shocks (adjusted HR 5.1, 95% CI 1.7-15.1, P=0.003). There were no differences in occurrence of inappropriate shocks.</AbstractText>Our study demonstrates that history of AF is associated with increased risk of appropriate shocks and cardiovascular mortality in primary prevention ICD patients with left ventricular dysfunction.</AbstractText> |
9,460 | Left ventricular dysfunction in atrial fibrillation: restoration of sinus rhythm by the Cox-maze procedure significantly improves systolic function and functional status. | Atrial flutter or fibrillation with rapid, uncontrolled ventricular response may lead to left ventricular dysfunction, and conversion to sinus rhythm with control of heart rate can improve left ventricular ejection fraction. Little is known about the effects of the Cox-maze procedure on this form of tachycardia-induced cardiomyopathy.</AbstractText>Four hundred forty-three patients underwent the Cox-maze procedure from 1993 to 2002. Ninety-nine had atrial flutter or fibrillation without associated valvular or congenital heart disease, and 37 (37%) had decreased left ventricular function (ejection fraction < 0.35 in 11 [severe], ejection fraction 0.36 to 0.45 in 8 [moderate], and ejection fraction 0.46 to 0.55 in 18 [mild]). Ages of these 37 patients (34 male) ranged from 35 to 74 years (median, 55 years).</AbstractText>Atrial flutter or fibrillation was present for 3 months to 19 years (median, 48 months) preoperatively, and 24 patients (65%) exhibited symptoms of heart failure. Preoperative ejection fraction ranged from 0.25 to 0.55 (median, 0.45). At last follow-up (median, 63 months), the Cox-maze procedure eliminated atrial flutter or fibrillation in all but 1 patient, and the greatest improvement was observed in patients with severe preoperative impairment (0.31 to 0.53; p = 0.01, preoperative versus follow-up), and patients with preoperative chronic atrial flutter or fibrillation (0.43 to 0.55; p < 0.05 preoperative versus follow-up). This improvement was observed immediately postoperatively and was sustained at last follow-up. Further, improvement in left ventricular function correlated with enhancement of functional status.</AbstractText>In some patients, atrial flutter or fibrillation may be the cause rather than the consequence of left ventricular dysfunction. Importantly, systolic function and functional status can be significantly improved with the restoration of sinus rhythm by the Cox-maze procedure.</AbstractText> |
9,461 | Stepwise approach to substrate modification of ventricular tachycardia after myocardial infarction. | Recently, substrate mapping (SM) has been described to facilitate catheter ablation of stable and unstable ventricular tachycardia (VT) after myocardial infarction. However, SM is time consuming with potential disadvantages of multiple ablation lines such as impairment of ventricular function or proarrhythmia. The aim of the present study was to delineate a stepwise approach to SM to shorten procedure time and limit the possibility of complications.</AbstractText>SM was performed in 14 infarct survivors referred for VT ablation using an electroanatomical mapping system (CARTO) to define infarct regions. A new stepwise approach for SM was designed as follows. The initial ablation site was identified by pace- and entrainment mapping in case of stable VT and by pace mapping only in case of unstable VT. Based on the CARTO voltage mapping, linear ablation was done from this site to the center of the scar and perpendicular to the boundary of the scar or to the mitral annulus. Additional lines were performed only when VT remained inducible. A maximum of 3 ablation lines were created during one procedure.</AbstractText>A total of 57 VTs (21 stable, 36 unstable) were induced during the procedures. VT was no longer inducible after the first linear ablation in 2 patients, after the second linear ablation in 6 patients and after the third linear ablation in 3 patients. Either VT or ventricular fibrillation was still inducible at the end of the procedure in 3 patients. Procedure time averaged (291 +/- 85) minutes, fluoroscopy time (10 +/- 7) minutes. VT recurred in 3 patients. Following a second procedure in 2 patients, there were no further VT recurrences. Overall, there was a significant reduction in VT episodes 3 months after [median: 0, interquartile ranges (IQR): 0 - 1] compared with 3 months before ablation (median: 25, IQR: 16 - 105, P < 0.01).</AbstractText>This stepwise approach to SM is effective in facilitating ablation of stable and unstable VT. It reduces procedure and fluoroscopy time, and may help to improve the risk-benefit ratio of VT ablation.</AbstractText> |
9,462 | [Improvement of thrombocytopenia with normalization of thyroid function in a patient with Graves disease]. | A 39-year-old man was admitted to our hospital because of hyperthyroidism complicated with fever, atrial fibrillation with rapid ventricular response and congestive heart failure. Laboratory data revealed pancytopenia with a white blood cell count of 3360/microl, Hb 9.6 g/dl, and a platelet count of 88000/ul. After initiation of treatment with 30 mg of thiamazole daily, the patient's thyroid function improved but 4 weeks later, thiamazole induced agranulocytosis occurred and the drug was discontinued. After recovery from agranulocytosis, a subtotal thyroidectomy was performed, and the patient's pancytopenia rapidly improved. In this case, hyperthyroidism itself appeared to be closely related to the development of thrombocytopenia. |
9,463 | Review of the molecular pharmacology of Losartan and its possible relevance to stroke prevention in patients with hypertension. | The Losartan Intervention For End-point reduction in hypertension (LIFE) study found that a losartan-based regimen, compared with an atenolol-based regimen, resulted in a significantly lower risk of stroke in hypertensive patients with left ventricular hypertrophy, despite similar reductions in blood pressure.</AbstractText>The purpose of this review was to examine the molecular and pharmacologic mechanisms that may be associated with the different outcomes observed in the LIFE study.</AbstractText>A PubMed/MEDLINE search of English-language articles (1990 to February 2006) with the terms angiotensin II antagonists or AIIAs or angiotensin receptor blockers or losartan or atenolol or beta blocker and terms including, but not limited to, atherosclerosis, left ventricular hypertrophy, carotid artery hypertrophy, fatty streaks, atrial fibrillation, arrhythmias, endothelial function, myocyte hypertrophy, myocardial fibrosis, platelet aggregation, tissue factor, plasminogen activator inhibitor-1, PAI-1, anti-inflammatory, uric acid, or oxidative stress.</AbstractText>Losartan's significant effect on stroke may be related to several possible mechanisms that are independent of blood-pressure reductions. These include improvements in endothelial function and vascular structure; decreases in vascular oxidative stress; reductions in left ventricular hypertrophy, reductions in myocardial fibrosis, or both; and modulation of atherosclerotic disease progression. Although some of these effects may be shared by other angiotensin II receptor antagonists (AIIAs), and perhaps other anti-hypertensive classes (eg, angiotensin-converting enzyme inhibitors), the ability of losartan to lower serum uric acid levels-a proposed independent risk factor for cardiovascular disease-appears to be a molecule-specific effect. Alternative explanations of the results of the LIFE study have also been hypothesized, including inappropriate choice of atenolol as an active comparator and differences in central pulse pressures between study groups.</AbstractText>This review of the literature suggests that losartan (and perhaps other AIIAs) may possess a number of properties, independent of its antihypertensive effects, that may be associated with decreased vulnerability of the plaque, myocardium, and blood.</AbstractText> |
9,464 | A critical re-appraisal of different ways of selecting ambulatory patients with suspected heart failure for echocardiography. | ECG and BNP have been assessed as screening tests for LVSD and heart failure. However, echocardiography also provides information about valvular disease and LVH. We assessed how good these screening tests are in identifying whether the subsequent echocardiogram will have any significant abnormality.</AbstractText>To re-appraise the ECG and BNP as screening tests for echocardiography since there are important practical deficiencies in our current knowledge in this area.</AbstractText>General practitioners referred suspected heart failure patients for clinical assessment, echocardiography, electrocardiography, and BNP measurement. The accuracy of each screening test and combinations of screening tests were calculated for LVSD, heart failure, valvular disease, and LVH.</AbstractText>The sensitivities of the ECG for LVSD, heart failure, LVH and valvular disease were 97%, 95%, 76%, and 69%, respectively. The corresponding figures for BNP were 86%, 82%, 59%, and 48%, respectively. When patients with atrial fibrillation and murmurs were excluded, the values for ECG were 94%, 87%, 53%, and 55%, while for BNP they were 83%, 73%, 50%, and 32%.</AbstractText>ECG interpretation and BNP are adequate screening tests to detect LVSD or heart failure but fail to screen for other echocardiographic abnormalities, like valvular disease and LVH. This remains the case even if patients with atrial fibrillation or heart murmurs are excluded on the basis that they require echocardiography anyway.</AbstractText> |
9,465 | Near-fatal incident on routine induction of ventricular fibrillation at the replacement of an implantable cardioverter defibrillator. | The case of a 54-year-old patient with severe coronary artery disease and storms of ventricular tachyarrhythmias is presented. On the replacement of an implantable cardioverter defibrillator due to battery depletion, he suffered life-threatening complications associated with arrhythmia induction. Performing a routine induction of ventricular arrhythmias on the occasion of pulse generator replacement may be reconsidered in selected patients. |
9,466 | Biphasic transoesophageal vs. transthoracic electrical cardioversion of persistent atrial fibrillation. | To compare the efficacy and safety of transoesophageal (TOC) vs. transthoracic (TTC) electrical cardioversion, both with biphasic shocks, for sinus rhythm (SR) restoration in patients with persistent atrial fibrillation (AF).</AbstractText>We randomised 210 patients (151 male, 59 female, mean age 66 +/- 9 years) with persistent AF into two groups: group 1 (n = 104) undergoing TOC with a step-up protocol of 30, 50, 70 and 100 J, and group 2 (n = 106) undergoing TTC with a step-up protocol of 70, 100, 120 and 150 J.</AbstractText>The two groups were homogeneous as for clinical and instrumental characteristics, except for left ventricular ejection fraction (50.5 +/- 10% in group 1 vs. 53 +/- 8% in group 2, P < 0.05) and thoracic impedance (63 +/- 8 Omega in group 1 vs. 66 +/- 6 Omega in group 2, P < 0.005). SR was restored in 98 (94%) group 1 patients vs. 99 (93%) group 2 patients (P = NS). First shock was effective in 48 (46%) group 1 patients vs. 54 (51%) group 2 patients (P = NS). Mean delivered energy was 50.4 +/- 23.6 and 95.1 +/- 29.6 J; mean effective energy was 47.3 +/- 20.7 and 91.2 +/- 26.6 J in group 1 and group 2, respectively. Cross-over to the highest energy level was never effective. TOC tolerability was optimal (mean discomfort score 1.2 on a 1-4 grading scale). Markers of myocardial necrosis did not increase and no procedure-related complications occurred. On logistic regression analysis, the most predictive variables of unsuccessful cardioversion were AF duration (P = 0.0001) and low left atrial appendage emptying velocity (P = 0.02).</AbstractText>Both TOC and TTC with biphasic shocks are effective and safe for SR restoration in patients with persistent AF; however, the considerably lower levels of delivered and effective energies for SR restoration allow TOC to be performed during mild sedation with optimal tolerability, thus avoiding general anaesthesia.</AbstractText> |
9,467 | [Hilbert transform analysis of the relation between ventricular fibrillation voltage and the outcome of defibrillation shocks]. | The objective of this study is to evaluate the correlation between the absolute ventricular fibrillation voltage (AVFV) computed from electrocardiogram (ECG) and the outcome of defibrillation shocks. Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) was recorded from 11 dogs during 10 seconds of electrically induced ventricular fibrillation followed by defibrillation shocks with 50% probability of success. The transvenous two-leads defibrillation system was used to deliver defibrillation shocks. The envelope voltage was estimated by using the Hilbert transform. The comparison of the envelope voltages between 236 successful trials and 249 unsuccessful trials did not show any consistent and statistically significant differences. In contrast with the previously reported correlation, the moving average of AVFV was not higher in the successful trials. In the Z direction, the successful trials had lower voltage than did the unsuccessful trials (P < 0.05). These results suggest that the absolute voltage of ECG during ventricular fibrillation is not robustly correlated with the outcome of defibrillation shocks. |
9,468 | The protective effect of L-carnitine on ischemia-reperfusion heart. | To investigate the protective effect of L-carnitine on myocardial ischemia-reperfusion injury in rat heart,all harvested isolated hearts were perfused on Langendorff apparatus with oxygenized K-H solution for 20 min. The hearts were then exposed to ischemia for 30 min. Following the ischemia the hearts were re-perfused with K-H solution for 120 min to serve as the control group A. Either 5 or 10 mmol/L of L-carnitine was added into the K-H solution for 20 min at the beginning of reperfusion to generate group B and group C, respectively. The derivatives of the intraventricular pressure curve (DP/DT), left ventricular developed pressure (LVDP), and coronary flux were monitored during the entire experiment. The levels of ATP, hepatin, malondialdehyde (MDA), and superoxide dismutase (SOD) in tissue, and lactic dehydrogenase (LDH), creatine phosphate kinase (CPK), malondialdehyde (MDA), and superoxide dismutase (SOD) concentration in the coronary efflux were all measured. Compared with the control group, the treatment with L-carnitine resulted in better results, i. e., higher DP/DTmax and LVDP. At the same time, ventricular fibrillation was reduced, and the levels of ATP, hepatin and SOD were all elevated. However, the concentrations of MDA, CPK and LDH were all reduced. In conclusion, L-carnitine has a protective effect on ischemia-reperfusion injury, which is partly due to its prevention of energy loss and its antioxidant activity. |
9,469 | Tetramethylpyrazine induces heme oxygenase-1 expression and attenuates myocardial ischemia/reperfusion injury in rats. | The accumulation of oxygen free radicals and activation of neutrophils are strongly implicated as pathophysiological mechanisms mediating myocardial ischemia/reperfusion injury. Heme oxygenase-1 (HO-1) has been reported to play a protective role in oxidative tissue injuries. In this study, the cardioprotective activity of tetramethylpyrazine (TMP), an active ingredient of Chinese medicinal herb Ligusticum wallichii Franchat, was evaluated in an open-chest anesthetized rat model of myocardial ischemia/reperfusion injury. Pretreatment with TMP (5 and 10 mg/kg, i.v.) before left coronary artery occlusion significantly suppressed the occurrence of ventricular fibrillation. After 45 min of ischemia and 1 h of reperfusion, TMP (5 and 10 mg/kg) caused a significant reduction in infarct size and induced HO-1 expression in ischemic myocardium. The HO inhibitor ZnPP (50 microg/rat) markedly reversed the anti-infarct action of TMP. Superoxide anion production in ischemic myocardium after 10 min reperfusion was inhibited by TMP. Furthermore, TMP (200 and 500 microM) significantly suppressed fMLP (800 nM)-activated human neutrophil migration and respiratory burst. In conclusion, TMP suppresses ischemia-induced ventricular arrhythmias and reduces the infarct size resulting from ischemia/reperfusion injury in vivo. This cardioprotective activity of TMP may be associated with its antioxidant activity via induction of HO-1 and with its capacity for neutrophil inhibition. |
9,470 | Torsades de pointes as a cause of sudden death in a patient with aortic stenosis and atrial fibrillation. | The occurrence of sudden cardiac death during Holter monitoring in patients with aortic stenosis has been reported previously. In the majority of the reported cases, the cause of death was a malignant ventricular tachyarrhythmia. The presence of a strong association between frequency and complexity of ventricular arrhythmias and sudden death in patients with aortic stenosis has been proposed. We report the case of a 77-year-old woman with aortic stenosis and atrial fibrillation who had an episode of torsades de pointes that degenerated into ventricular fibrillation during Holter monitoring. A short-long-short sequence, but not increased ventricular ectopics, precipitated torsades de pointes and sudden death in this case which is strongly indicative of triggered activity as the underlying mechanism of the lethal arrhythmia. |
9,471 | Internal cardioversion shortens periods of postoperative atrial fibrillation: results of a prospective, multicenter trial. | Atrial fibrillation (AF) commonly occurs following open heart surgery especially in the high-risk group of old patients with reduced left ventricular function. Via Syncrus heart wires implanted on the left and right atrium internal cardioversion shocks can be applied. This prospective nonrandomized multicenter study compares duration of AF periods and clinical outcome in patients treated with Syncrus wires to a control group treated conventionally.</AbstractText>In 88 patients Syncrus heart wires were implanted. Upon detection of AF antiarrhythmic medication was started for at least 6 hours followed by internal cardioversion. The results of this treatment were compared to a control group of 86 patients with an identical risk profile.</AbstractText>In the Syncrus group 53.4% of patients suffered from postoperative AF compared with 50.0% in the control group. Internal cardioversion led to restoration of sinus rhythm in 60% of patients at the first series of shocks (mean energy 7.7 +/- 1.3 J) and 95.8% with the second series (mean energy 8.6 +/- 0.5 J). Length of AF periods was 12.4 +/- 7.2 hours in the Syncrus group versus 42.9 +/- 19.6 hours in control patients.</AbstractText>Internal cardioversion using Syncrus heart wires demonstrated effectiveness in treating postoperative AF. Especially, length of AF periods could be diminished by the system with the expectation of reduction in hospital length of stay.</AbstractText> |
9,472 | Respiratory modulation of the autonomic nervous system during Cheyne-Stokes respiration. | Cheyne-Stokes respiration (CSR) is associated with increased mortality among patients with heart failure. However, the specific link between CSR and mortality remains unclear. One possibility is that CSR results in excitation of the sympathetic nervous system. This review relates evidence that CSR exerts acute effects on the autonomic nervous system during sleep, and thereby influences a number of cardiovascular phenomena, including heart rate, blood pressure, atrioventricular conduction, and ventricular ectopy. In patients in sinus rhythm, heart rate and blood pressure oscillate during CSR in association with respiratory oscillations, such that both peak heart rate and blood pressure occur during the hyperpneic phase. Inhalation of CO2 abolishes both CSR and the associated oscillations in heart rate and blood pressure. In contrast, O2 inhalation sufficient to eliminate hypoxic dips has no significant effect on CSR, heart rate, or blood pressure. In patients with atrial fibrillation, ventricular rate oscillates in association with CSR despite the absence of within-breath respiratory arrhythmia. The comparison of RR intervals between the apneic and hyperpneic phases of CSR indicates that this breathing disorder exerts its effect on ventricular rate by inducing cyclical changes in atrioventricular node conduction properties. In patients with frequent ventricular premature beats (VPBs), VPBs occur more frequently during the hyperpneic phase than the apneic phase of CSR. VPB frequency is also higher during periods of CSR than during periods of regular breathing, with or without correction of hypoxia. In summary, CSR exerts multiple effects on the cardiovascular system that are likely manifestations of respiratory modulation of autonomic activity. It is speculated that the rhythmic oscillations in autonomic tone brought about by CSR may ultimately contribute to the sympatho-excitation and increased mortality long observed in patients with heart failure and CSR. |
9,473 | Aortic valve replacement and long-term prognosis. | We assessed the long-term risk of mortality associated with mechanical and biological aortic valve replacement (AVR).</AbstractText>We reviewed articles published during the last decade, with emphasis on large series reporting mortality data and follow up of 5 years or longer. The latest editions of textbooks on cardiology and cardiac surgery were also reviewed. We used mortality analysis methodology, comparing the observed mortality in these series to the expected mortality calculated from country specific life tables, to calculate the risk of mortality expressed as the mortality ratio (MR), values above 100% traducing the excess risk of mortality compared to the general population.</AbstractText>After AVR, the MR varied from 120% to 350% for mechanical valve prostheses, and from 100% to 300 for bioprosthetic valves according to age at surgery. MR above 400% was associated with an AVR before the age of 50 years. No significant difference in the MR over age 50 years was found between mechanical and biological AVR. Independent prognostic factors after AVR are age at surgery, New York Heart Association (NYHA) functional class at time of surgery, left ventricular ejection fraction (LVEF), atrial fibrillation, and type and severity of valvular lesion.</AbstractText>No difference was found for excess mortality between mechanical and biological AVR. Under the age of 50 years, higher mortality was associated with both mechanical and bioprosthetic AVR.</AbstractText> |
9,474 | Coronary vasospasm-induced acute coronary syndrome complicated by life-threatening cardiac arrhythmias in patients without hemodynamically significant coronary artery disease. | Coronary vasospasm-induced electrical and mechanical complications in patients with acute coronary syndrome and no hemodynamically significant coronary artery disease are rarely reported.</AbstractText>A total of 733 consecutive patients with acute coronary syndrome admitted to our hospital who subsequently underwent coronary angiography at our institution were enrolled. Patients who had documented complete atrioventricular block or ventricular fibrillation, no evidence of hemodynamically significant coronary artery disease on coronary angiogram, and no other (non-coronary) cardiac abnormalities were included. Patients were followed for subsequent cardiac events and mortality.</AbstractText>Over a 6-year period at our institution, acute coronary syndrome complicated by life-threatening cardiac arrhythmias developed in six patients who had no hemodynamically significant coronary artery disease with corresponding intra-coronary ergonovine provocative coronary vasospasm. Acute myocardial infarction was diagnosed in five of these patients and variant angina pectoris in one. Complete atrioventricular block was the most common complication in these cases, followed by cardiogenic shock with or without right ventricular infarction, ventricular fibrillation, and severe sinus arrest. These complications were corrected with intravenous fluid, intravenous atropine or cardiac defibrillation. During a median follow-up period of 26 months, none of the patients expired or suffered nonfatal reinfarction. Two individuals who did not stop smoking during follow-up developed recurrent angina after self-discontinuation of calcium antagonists.</AbstractText>Coronary vasospasm can be a cause of life-threatening cardiac arrhythmias in patients with acute coronary syndrome and no hemodynamically significant coronary artery disease. Coronary angiography with/without intra-coronary ergonovine testing is necessary in acute coronary syndrome patients to identify the underlying pathology and establish appropriate treatment in these cases.</AbstractText> |
9,475 | Prognosis of decompensated heart failure patients with preserved systolic function is predicted by NT-proBNP variations during hospitalization. | Almost half of heart failure (HF) patients have preserved left ventricular systolic function (LVSF). Although morbidity is similar in patients with preserved and depressed LVSF, clinicians have limited information on prognostic factors of patients with preserved LVSF. We aimed to evaluate the prognostic value of NT-proBNP in patients with decompensated HF regardless of LVSF.</AbstractText>Patients hospitalised due to decompensated HF were followed for 6 months. The primary endpoint was death or hospital readmission. We evaluated 224 patients with NT-proBNP measured at admission and discharge and an echocardiogram performed. NT-proBNP decreased on average during hospitalization in patients with preserved LVSF (n=63) and in patients with depressed LVSF (n=161). The morbidity was not different between patients with preserved and depressed LVSF. Among patients with preserved LVSF, predictors of adverse events were serum creatinine, haemoglobin, NT-proBNP levels at discharge and the variation in NT-proBNP during hospitalisation. Among patients with depressed LVSF, predictors of adverse events were female gender, atrial fibrillation, non-prescription of ACE-inhibitor at discharge, NT-proBNP levels at discharge and the variation in NT-proBNP during hospitalisation.</AbstractText>These results suggest that, in HF patients with preserved LVSF as in patients with depressed LVSF, NT-proBNP can play a role as a tool to identify patients at risk of an adverse outcome.</AbstractText> |
9,476 | Human cardiac ryanodine receptor mutations in ion channel disorders in Japan. | Catecholaminergic polymorphic ventricular tachycardia (CPVT) is characterized by adrenergic induced bidirectional or polymorphic ventricular tachycardias. Some of CPVT families were reported to be associated with cardiac ryanodine receptor gene (RyR2) mutations. However, association between RyR2 and other arrhythmogenic disorders is not clarified. In this study, we analyzed 83 Japanese patients including patients with long-QT syndrome, Brugada syndrome, idiopathic ventricular fibrillation, arrhythmogenic right ventricular cardiomyopathy and CPVT. Genetic screening of RyR2 revealed 3 distinct mutations among 4 families with CPVT (75% of incidence). However, no mutation was found in other groups. This is the first report to demonstrate prevalence of RyR2 mutations in various arrhythmogenic disorders in Japan. RyR2 mutations were detected frequently in CPVT but not in other diseases. |
9,477 | A comparison of empiric to physician-tailored programming of implantable cardioverter-defibrillators: results from the prospective randomized multicenter EMPIRIC trial. | The purpose of this randomized study was to determine whether a strategically chosen standardized set of programmable settings is at least as effective as physician-tailored choices, as measured by the shock-related morbidity of implantable cardioverter-defibrillator (ICD) therapy.</AbstractText>Programming of ventricular tachyarrhythmia (ventricular tachycardia [VT] or ventricular fibrillation [VF]) detection and therapy for ICDs is complex, requires many choices by highly trained physicians, and directly influences the frequency of shocks and patient morbidity.</AbstractText>A total of 900 ICD patients were randomly assigned to standardized (EMPIRIC, n = 445) or physician-tailored (TAILORED, n = 455) VT/VF programming and followed for 1 year.</AbstractText>The primary end point was met: the adjusted percentages of both VT/VF (22.3% vs. 28.7%) and supraventricular tachycardia or other non-VT/VF event episodes (11.9% vs. 26.1%) that resulted in a shock were non-inferior and lower in the EMPIRIC arm compared to the TAILORED arm. The time to first all-cause shock was non-inferior in the EMPIRIC arm (hazard ratio = 0.95, 90% confidence interval 0.74 to 1.23, non-inferiority p = 0.0016). The EMPIRIC trial had a significant reduction of patients with 5 or more shocks for all-cause (3.8% vs. 7.0%, p = 0.039) and true VT/VF (0.9% vs. 3.3%, p = 0.018). There were no significant differences in total mortality, syncope, emergency room visits, or unscheduled outpatient visits. Unscheduled hospitalizations occurred significantly less often (p = 0.001) in the EMPIRIC arm.</AbstractText>Standardized empiric ICD programming for VT/VF settings is at least as effective as patient-specific, physician-tailored programming, as measured by many clinical outcomes. Simplified and pre-specified ICD programming is possible without an increase in shock-related morbidity.</AbstractText> |
9,478 | Disopyramide is an effective inhibitor of mutant HERG K+ channels involved in variant 1 short QT syndrome. | The recently identified idiopathic short QT syndrome (SQTS) is associated with an increased risk of arrhythmia and sudden death. The use of implantable cardioverter defibrillators helps to protect SQTS patients from ventricular fibrillation; however, pharmacological treatments to normalise the QT interval are limited: thus far only quinidine has been found to be effective in a subset of patients, with the SQT1 variant. SQT1 is associated with an amino acid substitution (N588K) in the KCNH2-encoded HERG K(+) channel that reduces HERG current (I(HERG)) inactivation and sensitivity to drug block. We demonstrate here that the N588K-HERG mutation only slightly attenuates I(HERG) blockade by the Class Ia antiarrhythmic drug disopyramide (1.5-fold elevation of IC(50)), compared to quinidine (3.5-fold elevation of IC(50)) and the Class III antiarrhythmic drug E-4031 (11.5-fold elevation of IC(50)). Thus, of the drugs studied to date, disopyramide is the one least affected by the SQT1 HERG mutation. Disopyramide is associated with QT prolongation in normal use and our findings provide a rational basis for its evaluation as a treatment for SQT1. |
9,479 | Ventricular assistance with microaxial flow pump following mitral repair for dilated cardiomyopathy. | Postcardiotomy heart failure is still the main cause of death in patients undergoing palliative surgery for end-stage dilative cardiomyopathy. New micro-axial flow ventricular assisting devices (LVAD) have been suggested in such cases.</AbstractText>Evaluate the effect of the new LVAD on short-term outcome of a patient admitted for end-stage heart failure.</AbstractText>Case report.</AbstractText>One patient admitted for severe mitral regurgitation secondary to end-stage dilative cardiomyopathy and chronic atrial fibrillation (AF).</AbstractText>Preoperative intraaortic balloon pump (IABP) insertion, mitral plasty with radiofrequency ablation of AF, microaxial flow LVAD support.</AbstractText>The patient was unweanable from cardiopulmonary bypass until microaxial flow LVAD unloaded the left ventricle and restored adequate cardiac function. The patient was discharged home and is still well at 5 months folllow-up.</AbstractText>The miniinvasive insertion and withdrawal, low anticoagulation protocols, and the possibility of coupling with IABP make the microaxial flow LVAD promising for patients with end-stage heart failure undergoing surgery.</AbstractText> |
9,480 | Multifractal analysis of ventricular fibrillation and ventricular tachycardia. | A study of ventricular fibrillation and ventricular tachycardia was undertaken using multifractal analysis. By applying the method of direct determination of the f(alpha) singularity spectrum, the value of the area of the VF and VT singularity spectrum was calculated. The comparison between the results showed that the value of the area of the VF singularity spectrum tended to be larger than that of the value of the area of the VT singularity spectrum. This makes the multifractal singularity spectrum a powerful criterion for discriminating between VF and VT. |
9,481 | High mechanical efficiency of left ventricular arrhythmic contractions during atrial fibrillation. | We analyzed the frequency distribution of the left ventricular (LV) mechanical efficiency of individual arrhythmic beats during electrically induced atrial fibrillation (AF) in normal canine hearts. This efficiency is the fraction of the external mechanical work (EW) in the total mechanical energy measured by the systolic pressure-volume area (PVA). The mean, median, and mode of this efficiency (EW/PVA) were as high as 78%, 80%, and 81%, respectively, on average in six hearts. These high efficiencies were comparable to that of the regular beats in these hearts. The frequency distribution of the EW/PVA during AF tended to skew to the higher side in all the hearts. Since the EW/PVA is directly related to both the ventriculo-arterial (or afterload) coupling ratio (E(a)/E(max); E(a) = effective arterial elastance, E(max) = end-systolic ventricular elastance) and the ejection fraction on a per-beat basis, we also analyzed their frequency distributions. We found them to skew enough to account for the rightward skewed frequency distribution of the EW/PVA during AF with the unexpectedly high mean EW/PVA. These results indicate that the LV arrhythmia during AF per se does not directly suppress the mean level of LV mechanical efficiency in normal canine hearts. |
9,482 | Prevention of atrial fibrillation in patients with symptomatic chronic heart failure by candesartan in the Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM) program. | Atrial fibrillation (AF) is frequent in patients with chronic heart failure (CHF). Experimental and small patient studies have demonstrated that blocking the renin-angiotensin-aldosterone system may prevent AF. In the CHARM program, the effects of the angiotensin receptor blocker candesartan on cardiovascular mortality and morbidity were evaluated in a broad spectrum of patients with symptomatic CHF. CHARM provided the opportunity to prospectively determine the effect of candesartan on the incidence of new AF in this CHF population.</AbstractText>7601 patients with symptomatic CHF and reduced or preserved left ventricular systolic function were randomized to candesartan (target dose 32 mg once daily, mean dose 24 mg) or placebo in the 3 component trials of CHARM. The major outcomes were cardiovascular death or CHF hospitalization and all-cause mortality. The incidence of new AF was a prespecified secondary outcome. Median follow-up was 37.7 months. A conditional logistic regression model for stratified data was used.</AbstractText>6379 patients (83.9%) did not have AF on their baseline electrocardiogram. Of these, 392 (6.15%) developed AF during follow-up, 177 (5.55%) in the candesartan group and 215 (6.74%) in the placebo group (odds ratio 0.812, 95% CI 0.662-0.998, P = .048). After adjustment for baseline covariates, the odds ratio was 0.802 (95% CI 0.650-0.990, P = .039). There was no heterogeneity of the effects of candesartan in preventing AF between the 3 component trials (P = .57).</AbstractText>Treatment with the angiotensin receptor blocker candesartan reduced the incidence of AF in a large, broadly-based, population of patients with symptomatic CHF.</AbstractText> |
9,483 | Catheter ablation of right ventricular outflow tract tachycardia: value of defining coronary anatomy. | Thermal damage to coronary arteries during catheter ablation has been previously reported. Coronary artery damage during LV outflow tract ventricular tachycardia is well recognized. However, the relationship of the coronary arteries to the RV outflow tract during catheter ablation has not been delineated. The purpose of this study was to define the relationship between the RV outflow tract and the coronary arteries utilizing arteriography, echocardiography, CT angiography, and gross anatomic pathology.</AbstractText>The relationship of the coronaries to the RV outflow tract was analyzed in three patients groups: Group 1: patients (n = 10) undergoing RV outflow tract ventricular tachycardia; Group 2: patients (n = 50) undergoing CT coronary angiography; Group 3: patients (n = 4) undergoing echocardiography during open heart surgery and intracardiac echocardiography (ICE) during catheter ablation of atrial fibrillation (n = 5).</AbstractText>Group 1: The left main coronary artery was found to be 3.8 +/- 1.2 mm from the right ventricular outflow tract in patients undergoing ablation. Group 2: The minimum distance between the left main, left anterior descending, and right coronary artery to the RV outflow tract endocardial wall were 4.1 +/- 1.9 mm, 2.0 +/- 0.6 mm, and 4.3 +/- 1.9 mm (average +/- SD) respectively. Group 3: During open heart surgery using echocardiography, the minimum distance between the left main and the right coronary artery to the RV outflow tract were 3.4 +/- 0.35 mm and 2.0 +/- 0.1 mm, respectively. The distance between the let main coronary artery and the RVOT by ICE was 3.8 +/- 0.45 mm.</AbstractText>The major coronary arteries lie in close proximity of the RVOT, and their anatomic course should be taken into consideration during ablation of ventricular tachycardias arising from the RV outflow tract.</AbstractText> |
9,484 | Effect of an active abdominal pulse generator on defibrillation thresholds with a dual-coil, transvenous ICD lead system. | Many patients with implantable cardioverter defibrillators (ICDs) have older lead systems, which are usually not replaced at the time of pulse generator replacement unless a malfunction is noted. Therefore, optimization of defibrillation with these lead systems is clinically important. The objective of this prospective study was to determine if an active abdominal pulse generator (Can) affects chronic defibrillation thresholds (DFTs) with a dual-coil, transvenous ICD lead system.</AbstractText>The study population consisted of 39 patients who presented for routine abdominal pulse generator replacement. Each patient underwent two assessments of DFT using a step-down protocol, with the order of testing randomized. The distal right ventricular (RV) coil was the anode for the first phase of the biphasic shocks. The proximal superior vena cava (SVC) coil was the cathode for the Lead Alone configuration (RV --> SVC). For the Active Can configuration, the SVC coil and Can were connected electrically as the cathode (RV --> SVC + Can). The Active Can configuration was associated with a significant decrease in shock impedance (39.5 +/- 5.8 Omega vs. 50.0 +/- 7.6 Omega, P < 0.01) and a significant increase in peak current (8.3 +/- 2.6 A vs. 7.2 +/- 2.4 A, P < 0.01). There was no significant difference in DFT energy (9.0 +/- 4.6 J vs. 9.8 +/- 5.2 J) or leading edge voltage (319 +/- 86 V vs. 315 +/- 83 V). An adequate safety margin for defibrillation (> or =10 J) was present in all patients with both shocking configurations.</AbstractText>DFTs are similar with the Active Can and Lead Alone configurations when a dual-coil, transvenous lead is used with a left abdominal pulse generator. Since most commercially available ICDs are only available with an active can, our data support the use of an active can device with this lead system for patients who present for routine pulse generator replacement.</AbstractText> |
9,485 | The full stomach test as a novel diagnostic technique for identifying patients at risk of Brugada syndrome. | Autonomic modulation, particularly high vagal tone, plays an important role in the occurrence of ventricular tachyarrhythmias in the Brugada syndrome. Food intake modulates vagal activity. We assessed the usefulness of a novel diagnostic technique, the "full stomach test," for identifying a high-risk group in patients with a Brugada-type electrocardiogram (ECG).</AbstractText>In 35 patients with a Brugada-type ECG, we assessed 12-lead ECGs before and after a large meal, a pilsicainide pharmacological test, spontaneous ST-segment change, late potentials by signal-averaged ECG, microvolt T-wave alternans, and four other ECG parameters. These patients were divided into two groups (i.e., high-risk group [n = 17] and indeterminate risk group [n = 18]). The full stomach test was defined as positive when augmentation of characteristic ECG abnormalities was observed after meals. Thirteen patients had a prior history of life-threatening events such as aborted sudden death and syncope, with a total of 30 episodes. These episodes had a circadian pattern, at night and after meals. The full stomach test was positive in 17 of the study patients (49%). A positive test outcome was characterized by a higher incidence of a history of life-threatening events than a negative test outcome (P = 0.015, odds ratio = 7.1). In comparison between the two groups, the incidence (82%) of positive outcomes in the high-risk group was significantly higher than that (17%) in the indeterminate risk group (P = 0.0002).</AbstractText>Characteristic ECG changes diagnostic of Brugada syndrome are augmented by a large meal. These data are associated with a history of life-threatening events in Brugada syndrome.</AbstractText> |
9,486 | Risk stratification of individuals with the Brugada electrocardiogram: a meta-analysis. | We performed a meta-analysis of prognostic studies of patients with a Brugada ECG to assess predictors of events.</AbstractText>The Brugada syndrome is an increasingly recognized cause of idiopathic ventricular fibrillation; however, there is wide variation in the prognosis of patients with the Brugada ECG.</AbstractText>We retrieved 30 prospective studies of patients with the Brugada ECG, accumulating data on 1,545 patients. Summary estimates of the relative risk (RR) of events (sudden cardiac death [SCD], syncope, or internal defibrillator shock) for a variety of potential predictors were made using a random-effects model. The overall event rate at an average of 32 months follow-up was 10.0% (95% CI 8.5%, 11.5%). The RR of an event was increased (P < 0.001) among patients with a history of syncope or SCD (RR 3.24 [95% CI 2.13, 4.93]), men compared with women (RR 3.47 [95% CI 1.58, 7.63]), and patients with a spontaneous compared with sodium-channel blocker induced Type I Brugada ECG (RR 4.65 [95% CI 2.25, 9.58]). The RR of events was not significantly increased in patients with a family history of SCD (P = 0.97) or a mutation of the SCN5A gene (P = 0.18). The RR of events was also not significantly increased in patients inducible compared with noninducible by electrophysiologic study (EPS) (RR 1.88 [95% CI 0.62, 5.73], P = 0.27); however, there was significant heterogeneity of the studies included.</AbstractText>Our findings suggest that a history of syncope or SCD, the presence of a spontaneous Type I Brugada ECG, and male gender predict a more malignant natural history. Our findings do not support the use of a family history of SCD, the presence of an SCN5A gene mutation, or EPS to guide the management of patients with a Brugada ECG.</AbstractText> |
9,487 | Role of the posterior papillary muscle and purkinje potentials in the mechanism of ventricular fibrillation in open chest dogs and Swine: effects of catheter ablation. | Papillary muscle (PM) ablation may terminate ventricular fibrillation (VF) in rabbit hearts. Whether or not PM ablation prevents ventricular fibrillation (VF) induction in large animals is unknown.</AbstractText>We performed noncontact endocardial mapping and/or high-density epicardial mapping during VF in 12 dogs and 16 swine and tested the effects of posterior PM (PPM) ablation on VF inducibility.</AbstractText>During VF in progressive global ischemia (3 swine and 2 dogs), the highest dominant frequency (DF) was near PPM. The majority of the reentrant wavefronts during a propranolol infusion (swine) were anchored to the PPM. Purkinje potentials onset were recorded on the PPM both during sinus rhythm and during VF. Radiofrequency (RF) ablation of the endocardium on the PPM with a linear extension of the ablation line from the PPM to the mitral valve annulus and then the left ventricular apex in 7 dogs reduced the VF inducibility from 100% at baseline to 22% after ablation (P < 0.0001). RF applications to the anterolateral wall of dogs (n = 3) did not prevent VF induction. The application of RF energy near the PPM frequently initiated VF in swine (n = 7), preventing subsequent testing of VF inducibility.</AbstractText>In dogs and swine, the highest DF and majority of reentrant wavefronts during VF with acute global ischemia or during a propranolol infusion were located on the PPM. RF ablation targeted at the PPM reduced the inducibility of VF in normal dogs. However, the same ablation provoked incessant VF in swine, preventing subsequent testing of VF inducibility.</AbstractText> |
9,488 | Simultaneous atrial and ventricular anti-tachycardia pacing as a novel method of rhythm discrimination. | To evaluate a new discrimination algorithm for supraventricular (SVT) and ventricular (VT) tachycardias, based on the response to simultaneous (A+V) atrial (A) and ventricular (V) anti-tachycardia pacing (ATP).</AbstractText>Patients undergoing electrophysiological testing or dual-chamber implantable cardioverter-defibrillator (ICD) implantation were enrolled (N = 32) and underwent A+V ATP through a Marquis ICD with investigational software. If persisting after ATP, the rhythm was classified as VT if the first electrical event was sensed on the V channel and as an SVT otherwise.</AbstractText>Arrhythmia sequences (N = 275; 53 VT; 222 SVT) were analyzed in 26 patients (age = 51 +/- 17 years, 13 men, LVEF = 0.49 +/- 0.14). In response to A+V ATP, 55% of SVT versus 41% of VT episodes were terminated (P = NS). Termination of VT but not of SVT was more likely with faster (50% at ATP/arrhythmia cycle length (CL) = 0.81 vs 8% at ATP/arrhythmia CL = 0.88, P = 0.02) but not with longer ATP bursts (P = NS). Of the 115 arrhythmias that persisted after A+V ATP, the algorithm correctly classified 24 of 24 VT (GEE-adjusted sensitivity = 100%) and 85 of 91 SVT (GEE-adjusted specificity = 93%). Proarrhythmia was noted after two A+V ATP, in the form of atrial fibrillation induction and VT acceleration.</AbstractText>We describe a new algorithm that can discriminate between SVT and VT with a high sensitivity and specificity. This form of ATP can terminate 55% of SVT sequences. The performance of this new algorithm merits further testing in a large population of dual-chamber ICD patients.</AbstractText> |
9,489 | Binding site of a novel Kv1.5 blocker: a "foot in the door" against atrial fibrillation. | Kv1.5 channel blockers prolong atrial action potentials and may prevent atrial flutter or fibrillation without affecting ventricular repolarization. Here we characterize the mechanisms of action of 2'-{[2-(4-methoxy-phenyl)-acetylamino]-methyl}-biphenyl-2-carboxylic acid (2-pyridin-3-yl-ethyl)-amide (AVE0118) on Kv1.5 channels heterologously expressed in Xenopus laevis oocytes. Whole cell currents in oocytes were recorded using the two-microelectrode voltage clamp technique. AVE0118 blocked Kv1.5 current in oocytes with an IC50 of 5.6 microM. Block was enhanced by higher rates of stimulation, consistent with preferential binding of the drug to the open state of the channel. Ala-scanning mutagenesis of the pore domain of Kv1.5 identified the amino acids Thr479, Thr480, Val505, Ile508, Val512, and Val516 as important residues for block by AVE0118. A homology model of the pore region of Kv1.5 predicts that these six residues face toward the central cavity of the channel. In addition, mutation of two other S6 residues (Ile502 and Leu510) that are predicted to face away from the central cavity also diminished drug block. All these putative drug-binding residues are highly conserved in other Kv channels, explaining our finding that AVE0118 also blocked Kv1.3, Kv2.1, Kv3.1, and Kv4.3 channels with similar potency. Docking of AVE0118 into the inner cavity of a Kv1.5 pore homology model predicted an unusual binding mode. The drug aligned with the inner S6 alpha-helical domain in a manner predicted to block the putative activation gate. This "foot-in-the-door" binding mode is consistent with the observation that the drug slowed the rate of current deactivation, causing a crossover of tail current traces recorded before and after drug treatment. |
9,490 | Prevalence, clinical profile, and significance of left ventricular remodeling in the end-stage phase of hypertrophic cardiomyopathy. | End stage (ES) is a recognized part of the hypertrophic cardiomyopathy (HCM) disease spectrum. Frequency, clinical profile and course, and treatment strategies in these patients remain incompletely defined.</AbstractText>Three HCM cohorts comprised 1259 patients, including 44 (3.5%) characterized as ES with systolic dysfunction (ejection fraction <50% at rest; range 15% to 49%). ES developed at a wide age range (14 to 74 years), with 45% of patients < or = 40 years old. Although 29 patients (66%) died of progressive heart failure, had sudden death events, or underwent heart transplantation, 15 (34%) survived with medical management over 3+/-3 years. Duration from onset of HCM symptoms to ES identification was considerable (14+/-10 years), but ES onset to death/transplantation was brief (2.7+/-2 years). ES occurred with similar frequency in patients with or without prior myectomy (P=0.84). Appropriate defibrillator interventions were 10% per year in patients awaiting donor hearts. Most ES patients (n=23; 52%) showed substantial left ventricular (LV) remodeling with cavity dilatation. Less complete remodeling occurred in 21 patients (48%), including 5 with persistence of a nondilated and markedly hypertrophied LV. Pathology and magnetic resonance imaging showed extensive (transmural) fibrosis in 9 of 11 ES patients. At initial evaluation, patients who developed ES were younger with more severe symptoms, had a larger LV cavity, and more frequently had a family history of ES than other HCM patients.</AbstractText>ES of nonobstructive HCM has an expanded and more diverse clinical expression than previously appreciated, including occurrence in young patients, heterogeneous patterns of remodeling, frequent association with atrial fibrillation, and impaired LV contractility that precedes cavity dilatation, wall thinning, and heart failure symptoms. ES is an unfavorable complication (mortality rate 11% per year) and a sudden death risk factor; it requires vigilance to permit timely recognition and the necessity for defibrillator implantation and heart transplantation.</AbstractText> |
9,491 | Post-resuscitation reperfusion injury: comparison of periodic Gz acceleration versus Thumper CPR. | The effects of whole body, periodic acceleration (pGz) on cardiopulmonary resuscitation outcome, organ blood flow and tissue inflammatory injury were examined in an experimental pig model, and compared with Thumper (TH)-CPR. VF was induced in 16 pigs, and remained untreated for 3 min, followed by either pGz-CPR or TH-CPR for 15 min. Defibrillation attempts were made at 18 min of VF. Six of eight animals had ROSC in both groups. Post-arrest myocardial dysfunction was present in both groups and progressed over hours. pGz-CPR animals had less wall motion abnormality and higher left ventricular ejection fraction than TH-CPR. The post-resuscitation haemodynamic variables returned to baseline after 3h of ROSC in pGz-CPR group, and remained low in TH-CPR group. The brain blood flow during CPR was similar between TH-CPR and pGz-CPR, 17% and 20% of pre-fibrillation values, respectively. The cardiac blood flow during CPR was significantly lower in pGz-CPR than TH-CPR (TH: 10.2% and pGz: 1.9% of pre-fibrillation value), as well as in other organs. The brain and heart blood flow was significantly higher than pre-fibrillation values after 30 min of ROSC in both groups. The pGz group had significantly higher blood flow in brain, heart and kidney than TH-CPR after 30 min of ROSC. Blood flow in all organs decreased below pre-fibrillation values at 2h of ROSC. Tissue inflammatory injury progressed over hours in the post-resuscitation phase. pGz-CPR group had significantly lower myeloperoxidase (MPO) activity and plasma creatine phosphokinase (CPK) and cardiac troponin I, TNF-alpha, and IL-6 than TH-CPR. Results from the present study demonstrate again that pGz-CPR is an effective method of cardiopulmonary resuscitation, with less post-reperfusion injury compared to TH-CPR. |
9,492 | Effects of right ventricular pacing on intra-left ventricular electromechanical activation in patients with native narrow QRS. | Some patients with right ventricular (RV) apical pacing show contractile asynchrony of the left ventricle. Whether the asynchrony is due to RV pacing or was a preexistimg condition remains unknown. The aim of this study was to evaluate how much pacing from the RV apex affects left ventricular (LV) electromechanical activation and to assess whether the extent of LV asynchrony during RV pacing can be predicted by clinical, electrocardiographic, or echocardiographic findings obtained during spontaneous rhythm. We evaluated 56 patients with narrow QRS and preserved atrioventricular conduction who received permanent backup RV pacing. Intra-LV electromechanical activation was assessed during spontaneous rhythm and during pacing using tissue Doppler echocardiography. An abnormal intra-LV electromechanical delay (EMD) (defined as a >41-ms difference between the faster and slower activated LV wall) was found in 15 patients (27%) during spontaneous rhythm and 28 patients (50%) during RV pacing (p<0.001). Of the 9 baseline variables (age, gender, history of heart failure, QRS duration in spontaneous rhythm and during pacing, LV end-diastolic and end-systolic diameters, LV ejection fraction, and intra-LV EMD in spontaneous rhythm), an abnormal baseline intra-LV EMD and QRS duration of >85 ms were independent predictors of an abnormal intra-LV delay during RV pacing. RV apical pacing induces asynchrony of LV contractions in a substantial percentage of patients but not in all. Although normal baseline intra-LV electromechanical activation cannot exclude the development of significant asynchrony during RV pacing, the presence of preimplant LV asynchrony predicts for a worsening of this detrimental effect. |
9,493 | Diagnostic accuracy of irregularly irregular RR intervals in separating atrial fibrillation from atrial flutter. | Periodic electrocardiographic RR intervals are often used to separate atrial flutter (AFl) from atrial fibrillation (AF), but have not yet been validated. We hypothesized that irregularly irregular electrocardiographic RR intervals poorly identify AF from AFl, and that atrial wavefront regularity affects variability in atrioventricular conduction. We studied the electrocardiographic RR intervals in 66 patients referred for ablation of AFl (21 atypical and 21 typical) and AF (n=24) in relation to intracardiac activation. Receiver-operating characteristics showed that periodicity in 60% of RR intervals provided only 66% sensitivity and 86% specificity for typical AFl and failed to separate atypical AFl from AF. Fewer RR intervals were integer atrial/ventricular ratios in atypical than in typical AFl (50% vs 83%, p=0.005), reflecting greater SDs in atrial cycles (6.98+/-7.02 vs 3.10+/-1.62 ms, p=0.023), more variable AH intervals (56+/-28 vs 18+/-21 ms, p=0.002), longer AH intervals (185+/-65 vs 118+/-31 ms, p=0.01), and greater AH variability for any atrial cycle length (p=0.026). In conclusion, irregularly irregular RR intervals are not specific for AF, are common in AFl, and should not be used to conclusively separate AF from AFl in the absence of sawtooth flutter waves. Future studies should explore the relation among AFl circuit location, cycle variability, and atrioventricular nodal conduction. |
9,494 | NO-synthase inhibitors provide influence on protective effect of modified endotoxine diphosphoryl lipid A in a rat heart model of ischemic-reperfusion injury. | The present study was designed to assess whether a protective effect of the modified diphosphoryl lipid A (modLA) against myocardial ischemia-reperfusion injury (IRI) in rats can be related to the mechanism involving inducible nitric oxide synthase (iNOS). Pre-treatment with modLA significantly reduced the duration of both ventricular tachycardia (p < 0.01) and ventricular fibrillation (p < 0.001) compared to controls. Under these conditions the incidence of animal death was reduced (p < 0.05). The beneficial effect of modLA was markedly attenuated by the prior administration of selective iNOS inhibitor S-methylisothiourea (SMT). In this animal group, mortality was significantly increased (p < 0.01) partially in consequence of sustained ventricular arrhythmias. These results indicate that induction of iNOS can be responsible for cardioprotection of modLA. |
9,495 | The 12-lead electrocardiogram as a predictive tool of mortality after acute myocardial infarction: current status in an era of revascularization and reperfusion. | Many recently published studies established the admission electrocardiogram as an excellent source of prognostic information in patients presenting with acute myocardial infarction. Using our search criteria, we identified a large number of articles but selected only the most relevant in each category. The best predictors of increased short-term mortality are ventricular tachycardia (odds ratio [OR] 6.1, 95% CI 4.6-8.3), ST-segment deviations (OR 5.1, 95% CI 4.6-8.3), high-degree atrioventricular block (OR 5.1, 95% CI 2.1-11.9), and long QRS duration (OR 4.2, 95% CI 1.8-10.4). For increased long-term mortality, the best predictors were ST-segment depression (OR 5.7, 95% CI 2.8-11.6), ST-segment elevation (OR 3.3, 95% CI 2.1-5.1), and left bundle-branch block (OR 2.8, 95% CI 1.8-4.3). In addition, our review discusses electrocardiographic markers of poor outcome that were not independent risk factors on multivariate analysis, conflicting findings, and knowledge gaps that can help plan future research efforts. |
9,496 | A case report of emergency off-pump CABG in an aged patient with ACS renewing ventricular fibrillation. | An emergency off-pump coronary artery bypass (OPCAB) was performed successfully in an aged patient with acute coronary syndrome (ACS). The patient, an 80-year-old woman residing in a nursing home, suddenly lost consciousness during lunch. The electrocardiogram (ECG) showed ventricular fibrillation (Vf) but defibrillation successfully recovered the sinus rhythm. The patient was brought to our hospital as an emergency. She underwent emergency cardiac catheterization. Coronary angiography demonstrated severe three vessel disease with left main coronary trunk (LMT) stenosis. Even during intra-aortic balloon pumping (IABP), the hemodynamic state was unstable, with repeated development of ventricular tachycardia and fibrillation. An emergency coronary artery bypass without a cardiopulmonary bypass was performed. Saving her life was of primary importance and revascularization of the left anterior descending artery (LAD) branch, was performed. Thanks to the advances made in various devices, safe and reliable anastomoses have become possible in OPCAB applied to ACS. OPCAB for ACS have become safe and reliable anastomoses following development of various devices. We think that OPCAB is an effective surgical technique for coronary revascularization for emergency or serious cases involving elderly patients. |
9,497 | Decrease in amplitude of intracardiac ventricular electrogram and inappropriate therapy in patients with an implantable cardioverter defibrillator. | Intracardiac electrograms are important for discrimination of tachyarrhythmia by implantable cardioverter defibrillators (ICD). A low R-wave can cause not only undersensing of ventricular tachyarrhythmia but also inappropriate discharges due to oversensing of unexpected signals because of its characteristic sensing algorithm. Therefore, this study aimed to investigate adverse events associated with R-wave amplitude. We included 115 consecutive patients followed-up over one year after implantation of a transvenous ICD system. The status of the ICD was checked every 3 months and intracardiac ventricular electrograms were analyzed. The decrease in R-wave amplitude was high in arrhythmogenic hypertrophy cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy (ARVC), and sarcoidosis. Low R-waves (< 5.0 mV) were observed in 13 patients at a follow-up of 15 +/- 16 months after implantation, and the mean R-wave was 3.0 +/- 0.8 mV. The frequency of low R-waves was high in ARVC (38%), sarcoidosis (33%), and dilated cardiomyopathy (17%). All of the dilated cardiomyopathy patients with low R-waves had severe left ventricular dysfunction. Inappropriate ICD therapy resulting from T-wave oversensing occurred in 7 patients and the R-wave was < 5.0 mV in 6 of the patients. The frequency of inappropriate therapy was high in patients with sarcoidosis. In 3 patients, inappropriate therapy caused ventricular tachyarrhythmia. In conclusion, decreases in R-wave amplitude occurred in some progressive cardiac disorders and caused inappropriate ICD discharges having arrhythmogenicity. Physicians should attempt to obtain a high R-wave amplitude during ICD implantation and careful follow-up is required, especially in patients with ARVC or sarcoidosis. |
9,498 | Atrial strain rate echocardiography can predict success or failure of cardioversion for atrial fibrillation: a combined transthoracic tissue Doppler and transoesophageal imaging study. | The purpose of this study was to assess the feasibility of measuring left atrial dysfunction with tissue Doppler imaging derived strain rate and to explore its role in predicting the maintenance of sinus rhythm after cardioversion for atrial fibrillation.</AbstractText>Strain rate (SR) and tissue Doppler imaging (TDI) were performed with offline analysis of the basal left atrial wall (LA). SR detected a systolic (Ssr) and early diastolic (Esr) deformation induced by ventricular motion. LA dimensions and volume were measured. Left atrial appendage emptying (LAA_EV) and filling (LAA_FV) velocities were also obtained by transesophageal echocardiography. 27 healthy age-matched controls and 42 patients with AF before cardioversion were studied. Patients were grouped into (1): those who remained in sinus rhythm (group S, n=12) and (2) those who either failed cardioversion or reverted to AF within 4 weeks (group F, n=30). LA dimensions were significantly larger and atrial Esr was significantly lower in group F than group S (all p<0.01). LAA_EV and LAA_FV were not different between groups S and F. Multivariate regression analysis showed that a lower Esr and larger transverse LA diameter (LADtr) were independent predictors of failure of cardioversion (HR, 95% CI: 0.36, 0.14-0.88 and 2.85, 1.33-6.10, respectively). Esr combined with LADtr improved the sensitivity and specificity for predicting successful cardioversion.</AbstractText>SR can be measured in the basal LA wall in atrial fibrillation and the magnitude of the early diastolic SR could predict the success of cardioversion and the likelihood of maintenance of sinus rhythm.</AbstractText> |
9,499 | Up-regulated inflammatory factors endothelin, NFkappaB, TNFalpha and iNOS involved in exaggerated cardiac arrhythmias in l-thyroxine-induced cardiomyopathy are suppressed by darusentan in rats. | The exaggerated cardiac arrhythmias in cardiomyopathy induced by L-thyroxine treatment are related to ion channelopathies and to an abnormal endothelin (ET) pathway. It was hypothesized that an increased incidence of ventricular fibrillation (VF) could be mediated by inflammatory factors including the ET pathway, nuclear factor kappa B (NFkappaB), tumor necrosis factor-alpha (TNFalpha) and inducible nitric oxide synthase (iNOS). Abnormal expression of NFkappaB, TNFalpha, iNOS and enhanced VF are linked with the activated ET pathway and a significant reversion could be achieved by the selective endothelin A receptor antagonist darusentan. Cardiomyopathy in rats was produced by L-thyroxine treatment (0.3 mg kg(-1) d(-1), sc) for 10 days. The mRNA expression of the ET pathway, NFkappaB, TNFalpha, iNOS and the activity of the redox system were assayed in association with the incidence of VF produced by coronary ligation/reperfusion. Darusentan was administered on days 6-10 of L-thyroxine treatment. The VF incidence, which was higher in the l-thyroxine cardiomyopathy group, was suppressed by darusentan. The mRNA levels of preproET-1, endothelin converting enzyme, endothelin receptor A (ET(A)R), endothelin receptor B (ET(B)R), NFkappaB, TNFalpha and iNOS in left ventricle were up-regulated in the cardiomyopathic heart. There was significant oxidative stress in this cardiomyopathy model. Darusentan suppressed the up-regulated mRNA levels of ET(A)R, ET(B)R, NFkappaB, TNFalpha, and iNOS. These results indicate that the high incidence of VF which is related to up-regulation of inflammatory factors in the cardiomyopathic myocardium is significantly suppressed by selective ET(A)R blockade. |
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