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1,600 | The Midlands Trial of Empirical Amiodarone versus Electrophysiology-guided Interventions and Implantable Cardioverter-defibrillators (MAVERIC): a multi-centre prospective randomised clinical trial on the secondary prevention of sudden cardiac death. | MAVERIC was a randomised clinical trial designed to test the possibility of prospectively identifying patients who would benefit most from the implantable cardioverter-defibrillator (ICD) by electrophysiology (EP) study in the context of secondary prevention of sudden cardiac death (SCD) through comparing EP-guided interventions (anti-arrhythmic drugs, coronary revascularization, and ICD) against empirical amiodarone therapy.</AbstractText>Two hundred and fourteen survivors of sustained ventricular tachycardia (VT), ventricular fibrillation (VF) or SCD were randomized to either treatment strategy, pre-stratified for haemodynamic status at index event, and followed up for a median of 5 years.</AbstractText>Of the 106 amiodarone arm patients, 89 (84%) received the drug and 5 (5%) received an ICD after crossing over. Of the 108 EP arm patients, 31 (29%) received an ICD, 46 (43%) received anti-arrhythmic drugs only (mainly amiodarone or sotalol) and 18 (17%) received coronary revascularization but no ICD. No significant differences in survival or arrhythmia recurrence existed between the two treatment arms after 6 years. However, ICD recipients had a lower mortality than non-ICD recipients, regardless of allocated treatment (hazard ratio=0.54, p=0.0391).</AbstractText>Prospective selection of patients to receive the ICD by EP study did not improve survival compared with empirical amiodarone therapy among survivors of VT, VF or SCD, whereas ICD implantation improved survival regardless of allocated treatment. On this basis, routine EP study has no role in the management of such patients, who should be offered empirical ICD therapy according to the results of other secondary prevention ICD trials.</AbstractText> |
1,601 | New-onset sustained ventricular tachycardia and fibrillation early after cardiac operations. | Malignant ventricular tachyarrhythmia early after cardiac surgery is an uncommon arrhythmic complication but has a negative impact on mortality. The purpose of this study was to evaluate the incidence of new-onset sustained postoperative ventricular tachycardia-ventricular fibrillation and to identify risk factors for the dysrhythmia.</AbstractText>Demographic, clinical, operative, and postoperative data, including a variable of postoperative ventricular tachycardia, were prospectively obtained from 4748 patients undergoing nonemergency coronary artery bypass graft and(or) valve replacement with no history of sustained ventricular tachycardia or sudden death. A detailed analysis was performed to define the risk factors for the ventricular tachycardia and the prognostic impact of the arrhythmia on 30-day mortality was evaluated.</AbstractText>Forty-five patients (0.95%) had sustained ventricular tachycardia or ventricular fibrillation and the initial episode occurred 3.9 +/- 5.2 days (mean +/- standard deviation) after surgery. By multivariate analysis, female sex (odds ratio, 1.982), left ventricular ejection fraction (< 35%: > 50%, 4.771), the presence of pulmonary hypertension (3.066), the presence of systemic hypertension (2.391), and pump time (per 10 minutes, 1.085) were independently associated with the dysrhythmias. Early mortality of patients with the arrhythmia was 28.9%, strikingly higher than that of patients without ventricular tachycardia/ventricular fibrillation (1.9%).</AbstractText>Left ventricular ejection fraction is the strongest risk factor for new-onset postoperative sustained ventricular tachycardia-ventricular fibrillation; female sex, pump time, pulmonary and systemic hypertension are independent predictors of the dysrhythmias; the arrhythmia is associated with increased 30-day mortality after cardiac surgery.</AbstractText> |
1,602 | Review of the predictive value of the Langendorff heart model (Screenit system) in assessing the proarrhythmic potential of drugs. | Prolongation of the QTc interval of the electrocardiogram (ECG) is used as a surrogate marker for a rare, but life threatening, ventricular arrhythmia known as torsades de pointes (TdP). However, the clear link between QTc prolongation and the arrhythmogenic risk has not been demonstrated unequivocally. In the present review article, we examine (a) the current understanding of electrophysiological and pharmacological mechanisms linking changes in action potential (AP) properties with proarrhythmia and (b) the value of the isolated, paced Langendorff-perfused female rabbit heart model (Screenit system) in predicting the torsadogenic potential of drugs in man. The Screenit system records monophasic action potentials (MAPs) from which the following parameters are evaluated: action potential duration (APD), conduction, instability (indicative of beat to beat APD variability), triangulation (indicative of changes of Phase 3 repolarization), and reverse-use dependency (indicating that the APD is more prolonged at slow heart rates). So far, over 16,000 experiments have been conducted, including approximately 300 dedicated tests to evaluate, in a blinded manner, approximately 70 clinically used drugs. The drugs tested covered a wide range of compounds from various pharmacological and chemical classes with clinical torsadogenic propensity, as well as drugs without the latter effect in clinical settings. Overall, the Screenit system and its associated analysis classified the drugs based on their effects on AP morphology and conduction and additionally identified, in a qualitative manner, drugs clinically associated with TdP. Such an identification is based on the triangulation, reverse-use dependency, and instability of the AP, as well as on the direct indexes of proarrhythmia such as early afterdepolarization (EADs), ventricular tachycardia (VT), and ventricular fibrillation (VF). Overall, drugs that readily induce arrhythmia and/or EADs and/or causes triangulation, reverse-use dependency, and/or instability and/or a chaotic Poincaré plot in a range of concentrations likely to be achieved in man is likely to cause TdP in man, eventually. Only if none of these elements is present, at concentrations well exceeding the free therapeutic plasma concentration, can one expect that the drug will probably be devoid of torsadonenicity. Therefore, this in vitro model provides detailed information on the overall profile of drug-induced electrophysiological effects. In combination with other in vitro and in vivo repolarization assays and with pharmacokinetic data in man, it is a valuable tool to establish an integrated cardiovascular risk assessment of pharmaceutical compounds. |
1,603 | Anticoagulation in atrial fibrillation. | Anticoagulation with warfarin is the most effective means of reducing stroke in AF. The generally recommended INR goal is 2-3. Aspirin provides a modest degree of stroke protection in AF but is inferior to warfarin. Assessment of stroke risk is critical in determining whether to prescribe warfarin therapy to a patient with AF. The most important risk factors for stroke in AF are age over 65 years, hypertension, prior stroke, and left ventricular dysfunction or heart failure. The risk of warfarin may be less than commonly believed, but increases when warfarin is combined with aspirin. Patients with paroxysmal AF are not at lower risk of stroke than those with persistent AF and should be treated with warfarin. Apparently successful therapy with antiarrhythmic agents does not eliminate the need for anticoagulation. New antithrombotic therapies are being studied and may soon provide an alternative to warfarin. |
1,604 | Enalapril prevents perpetuation of atrial fibrillation by suppressing atrial fibrosis and over-expression of connexin43 in a canine model of atrial pacing-induced left ventricular dysfunction. | Effects of enalapril on a canine model of atrial pacing-induced atrial fibrillation (AF) with rapid ventricular responses were determined.</AbstractText>Four weeks of atrial rapid pacing was performed on twenty-four beagles pretreated with placebo (Group I, n = 14) or enalapril 1 mg/kg (Group II, n = 10). Atrial effective refractory period (ERP), P-wave width, duration of AF, and left ventricular ejection fraction (LVEF) were evaluated every week. AF cycle length was determined by spectral analyses of fibrillation waves. Quantitative analysis of histology was added.</AbstractText>After 4 weeks of pacing, P-wave width was longer in Group I than in Group II, and the duration of induced AF was significantly longer in Group I (59.6 +/- 66.3 seconds) than in Group II (3.6 +/- 3.4 seconds, P < 0.05). AF cycle length was longer in Group I than in Group II despite similar shortening of atrial ERP. Mean ventricular rate during rapid atrial pacing was not different between the two groups. LVEF similarly decreased in both groups. Interstitial fibrosis and expression of connexin43 was greater in Group I than in Group II (interstitial fibrosis, 9.2 +/- 8.4 versus 1.9 +/- 2.1%, P < 0.05; connexin43, 5.3 +/- 2.2 versus 1.1 +/- 1.1%, P < 0.05).</AbstractText>Enalapril suppressed atrial pacing-induced AF with tachycardia-mediated cardiomyopathy by suppressing interstitial fibrosis, connexin43 over-expression and conduction delay.</AbstractText> |
1,605 | Brain function after resuscitation from cardiac arrest. | In industrial countries the incidence of cardiac arrest is still increasing. Almost 80% of cardiac arrest survivors remains in coma for varying lengths of time and full cerebral recovery is still a rare event. After successful cardiopulmonary resuscitation, cerebral recirculation disturbances and complex metabolic postreflow derangements lead to death of vulnerable neurons with further deterioration of cerebral outcome. This article discusses recent research efforts on the pathophysiology of brain injury caused by cardiac arrest and reviews the beneficial effect of therapeutic hypothermia on neurologic outcome along with the recent approach to prognosticate long-term outcome by electrophysiologic techniques and molecular markers of brain injury.</AbstractText>Recent experimental studies have brought new insights to the pathophysiology of secondary postischemic anoxic encephalopathy demonstrating a time-dependent cerebral oxidative injury, increased neuronal expression, and activation of apoptosis-inducing death receptors and altered gene expression with long-term changes in the molecular phenotype of neurons. Recently, nuclear MR imaging and MR spectroscopic studies assessing cerebral circulatory recovery demonstrated the precise time course of cerebral reperfusion after cardiac arrest. Therapeutic hypothermia has been shown to improve brain function after resuscitation from cardiac arrest and has been introduced recently as beneficial therapy in ventricular fibrillation cardiac arrest.</AbstractText>Electrophysiologic techniques and molecular markers of brain injury allow the accurate assessment and prognostication of long-term outcome in cardiac arrest survivors. In particular, somatosensory evoked potentials have been identified as the method with the highest prognostic reliability. A recent systematic review of 18 studies analyzed the predictive ability of somatosensory evoked potentials performed early after onset of coma and found that absence of cortical somatosensory evoked potentials identify patients not returning from anoxic coma with a specificity of 100%.</AbstractText> |
1,606 | Waveforms for defibrillation and cardioversion: recent experimental and clinical studies. | The advent of biphasic waveforms for external defibrillation has generated extensive experimental and clinical investigation. At the same time, it has led to the development and clinical use of biphasic waveforms of several different designs. Finally, other types of waveforms, primarily triphasic, have entered experimental evaluation.</AbstractText>There is virtually universal agreement that biphasic waveforms, regardless of design, have greater efficacy in defibrillation of ventricular fibrillation and in cardioversion of atrial fibrillation when compared with monophasic waveforms. It remains unresolved, however, whether any specific biphasic waveform has greater clinical superiority than others. Likewise, it remains to be demonstrated whether any biphasic waveform is less injurious to myocardial function than another and whether injury, if it is incurred, is secondary to peak delivered current or to delivered energy. Biphasic truncated exponential waveforms are used by most manufacturers, whereas a rectilinear biphasic waveform and a pulsed waveform also are being used clinically.</AbstractText>Biphasic waveforms have supplanted monophasic waveforms for defibrillation and cardioversion. They include biphasic truncated exponential, rectilinear, and pulsed biphasic versions. At this time, there is no certain evidence of clinical superiority of one waveform over another in terms of either efficacy or myocardial injury.</AbstractText> |
1,607 | Combination of active compression decompression cardiopulmonary resuscitation and the inspiratory impedance threshold device: state of the art. | Over the past decade, the combination of active compression decompression (ACD) cardiopulmonary resuscitation (CPR) and an impedance threshold device (ITD) has been shown to significantly increase vital organ perfusion pressures and survival rates in animals and humans. The purpose of this review article is to summarize the recent advances with this new technology.</AbstractText>Building upon animal studies that demonstrated the benefit of the ITD used with either ACD CPR or standard CPR (S-CPR), four prospective, randomized clinical trials with ACD/ITD CPR have been recently completed. One blinded, out-of-hospital cardiac arrest trial (n = 21 patients) demonstrated that systemic blood pressures and coronary perfusion pressures were markedly higher when ACD/ITD CPR was used when compared directly with ACD CPR alone. The second blinded trial demonstrated that the combination of ACD/ITD CPR was effective with both a facemask and an endotracheal tube (n = 15 patients). A third randomized clinical trial (n = 210 patients) demonstrated that 24-hour survival rates for out-of-hospital cardiac arrest were more than 65% higher with ACD/ITD CPR than with S-CPR (P < 0.01). Neurologic function after cardiac arrest trended higher in patients with witnessed arrest who received ACD/ITD CPR than in those who received S-CPR(P < 0.07). In addition, when ACD/ITD CPR was applied later in the course of treatment, short-term survival rates were threefold higher in patients receiving ACD/ITD CPR (44%) than in those receiving S-CPR (14%)(P < 0.05). In that study, patients with the greatest chance for survival-those with witnessed cardiac arrest and an initial rhythm of ventricular fibrillation-had a 23% 24-hour survival rate with S-CPR versus a 58% 24-hour survival rate with ACD/ITD CPR (P < 0.01). It should be noted that this trial was performed in a city where an earlier study found no difference in outcomes between ACD CPR alone and S-CPR. The fourth clinical trial was a randomized, double-blinded study of 400 patients with out-of-hospital cardiac arrest treated by advanced life support personnel. All patients received ACD CPR: half were treated with a sham ITD and the other half were treated with an active ITD. Twenty-four hour survival, the primary endpoint, was 32% in the active ITD group versus 22% in the sham group (P < 0.05).</AbstractText>On the basis of the cumulative findings of these studies, it is concluded that ACD/ITD CPR provides superior vital organ blood flow and results in significantly higher short-term survival rates than do ACD CPR alone or S-CPR. Use of the ACD/ITD CPR technology optimizes perfusion of the heart and brain during cardiac arrest and results in the highest reported survival rates of any CPR device technology. Use of this technology should be encouraged while additional studies are under way to examine the potential long-term impact of this new technology.</AbstractText> |
1,608 | Continuous, noninvasive, and localized microvascular tissue oximetry using visible light spectroscopy. | The authors evaluated the ability of visible light spectroscopy (VLS) oximetry to detect hypoxemia and ischemia in human and animal subjects. Unlike near-infrared spectroscopy or pulse oximetry (SpO2), VLS tissue oximetry uses shallow-penetrating visible light to measure microvascular hemoglobin oxygen saturation (StO2) in small, thin tissue volumes.</AbstractText>In pigs, StO2 was measured in muscle and enteric mucosa during normoxia, hypoxemia (SpO2 = 40-96%), and ischemia (occlusion, arrest). In patients, StO2 was measured in skin, muscle, and oral/enteric mucosa during normoxia, hypoxemia (SpO2 = 60-99%), and ischemia (occlusion, compression, ventricular fibrillation).</AbstractText>In pigs, normoxic StO2 was 71 +/- 4% (mean +/- SD), without differences between sites, and decreased during hypoxemia (muscle, 11 +/- 6%; P < 0.001) and ischemia (colon, 31 +/- 11%; P < 0.001). In patients, mean normoxic StO2 ranged from 68 to 77% at different sites (733 measures, 111 subjects); for each noninvasive site except skin, variance between subjects was low (e.g., colon, 69% +/- 4%, 40 subjects; buccal, 77% +/- 3%, 21 subjects). During hypoxemia, StO2 correlated with SpO2 (animals, r2 = 0.98; humans, r2 = 0.87). During ischemia, StO2 initially decreased at -1.3 +/- 0.2%/s and decreased to zero in 3-9 min (r2 = 0.94). Ischemia was distinguished from normoxia and hypoxemia by a widened pulse/VLS saturation difference (Delta < 30% during normoxia or hypoxemia vs. Delta > 35% during ischemia).</AbstractText>VLS oximetry provides a continuous, noninvasive, and localized measurement of the StO2, sensitive to hypoxemia, regional, and global ischemia. The reproducible and narrow StO2 normal range for oral/enteric mucosa supports use of this site as an accessible and reliable reference point for the VLS monitoring of systemic flow.</AbstractText> |
1,609 | [Prediction of brain infarction in hypertensive patients]. | A 7-year prospective study of 379 hypertensive patients was conducted with primary comprehensive clinical and device examination of the patients in hospital followed by annual control in hospital or outpatient setting. Two groups were formed: with uncomplicated essential hypertension (EH)(n = 263, group 1); with EH complicated by brain infarction (BI) (n = 116, group 2). Overall prognostic correctness was 85.9%. BI was predicted by age, smoking, high intake of salt, absence of regular antihypertensive therapy, non-dipper pattern, low output, atherosclerotic changes of major head arteries, frequent paroxysms of cardiac fibrillation, ventricular extrasystole, abnormal blood rheology. Integral index of the patient condition calculated on the basis of the decisive prognosis rule (data of the primary examination + MI within 7-year follow-up) enables targeted prevention of cerebral complications. |
1,610 | Phase IV trial evaluating the effectiveness and safety of dofetilide. | Dofetilide gained Food and Drug Administration approval for persistent atrial fibrillation/flutter (AFF) based on 2 randomized, placebo-controlled, dose-ranging studies. Concerns of proarrhythmia have prompted the manufacturer to develop specific treatment guidelines.</AbstractText>To determine the effectiveness and safety of dofetilide in clinical practice as well as to ascertain whether clinicians are following established dosing guidelines.</AbstractText>This retrospective analysis evaluated guideline adherence and safety in patients who received dofetilide at a tertiary care medical center. Safety assessment included monitoring for the occurrence of excessive QTc interval prolongation and torsade de pointes. Excessive QTc interval prolongation was defined as >15% above baseline after the first dose or >500 msec following any dose (>550 msec in patients with ventricular conduction abnormalities). Patients were included in the effectiveness assessment if they received at least 36 hours of dofetilide for persistent AFF, received an appropriate dose per guidelines, and did not receive direct current cardioversion during the evaluation period. We compared the 36-hour conversion rate with dofetilide in this study with that observed in the EMERALD and SAFIRE-D trials using the Z test, and we evaluated the incidence of excessive QTc interval prolongation in high-risk subgroups by chi(2) analysis.</AbstractText>Investigators identified 107 patients. The primary indication for dofetilide was AFF, with 58.9% receiving the drug for paroxysmal disease. Prescribing followed established guidelines, except that it was used intermittently by nonconfirmed prescribers (5.6%) and/or at inconsistent doses (14%). Excessive prolongation of the QTc interval occurred in 17.8% of patients after the first dose and 26.2% during subsequent doses; prolongation was more common in those with structural heart disease (p < 0.01). No patients developed torsade de pointes. In the effectiveness assessment (n = 25), the conversion of persistent AFF at 36 hours was higher than in previous studies (48% vs 27.2%; p = 0.05).</AbstractText>In clinical practice, the conversion of persistent AFF with dofetilide is at least comparable to premarketing studies, with a similar safety profile. Institutions should continue to emphasize adherence with established treatment guidelines.</AbstractText> |
1,611 | Single nucleotide polymorphisms of the SCN5A gene in Han Chinese and their relation with Brugada syndrome. | Mutations in the cardiac sodium channel gene (SCN5A) may lead to a broad spectrum of familial arrhythmias, including long QT syndrome (LQTS), idiopathic ventricular fibrillation (IVF), and isolated cardiac conduction diseases. Recent studies have shown that polymorphisms in the SCN5A gene also play an important role in the manifestation of disorders involving cardiac excitability. In this study, we investigated the polymorphisms of the SCN5A gene in Han Chinese and its relation to Brugada syndrome (BS).</AbstractText>Genomic DNA was isolated from 120 unrelated healthy volunteers and 48 unrelated Brugada syndrome patients by means of standard procedures. All exons including the putative splicing sites of the SCN5A gene were amplified by PCR and sequenced directly or after subcloning using an ABI Prism 377 DNA sequencer.</AbstractText>A total of 5 single nucleotide polymorphisms (SNPs) were identified in the Han Chinese population, including 3 novel ones: G87A(A29A), 4245 + 82A > G, and G6174A. The allele frequencies of each SNP in the Han Chinese population were as follows: G87A (A29A) 27.5%, A1673G (H558R) 10.4%, 4245 + 82A > G 32.8%, C5457T (D1819D) 41.3%, and G6174A 44.9%. S1102Y and 10 other SNPs identified in other ethnic populations were not detected in this study. There was no significant difference in the allele frequency of A1673G (H558R) between different ethnic populations (all P > 0.5). On the other hand, the allele frequency of C5457T (D1819D) among Han Chinese was similar to its frequency among Japanese (P > 0.5), but higher than that among Americans (P < 0.005). The allele G1673 (R558) was over-represented in BS patients compared to controls (P < 0.005), but there was no significant difference in genotype frequencies at this locus. There were also no differences in either the allele or genotype frequencies of the 4 other identified SNPs when comparing BS patients with healthy controls.</AbstractText>The distribution of SCN5A SNPs may vary between different ethnicities. The polymorphism of A1673G might be associated with BS and may contribute to a susceptibility to BS in Han Chinese.</AbstractText> |
1,612 | [Clinical experience of landiolol for the treatment of intraoperative rapid atrial fibrillation]. | A 79-year-old woman with three vessel disease and mitral as well as tricuspid regurgitation underwent operation twice. Preoperatively she had atrial fibrillation and heart failure. The first operation was coronary artery bypass grafting (CABG), and the second was mediastinal dissection for mediastinitis one month after the CABG. In both operations she developed rapid atrial fibrillation and ventricular fibrillation, showing her cardiac irritablility. Both operations were performed under cardiopulmonary bypass and support. In the first operation digoxin and verapamil partly reduced heart rate of rapid atrial fibrillation from 140-170 to 110-140 beats x min-1, which made us use another drug, a short acting selective beta 1 blocker landiolol in the second operation. Landiolol successfully reduced the heart rate of rapid atrial fibrillation from 140-160 to 80-90 beats x min-1. This case demonstrates that landiolol can be safely used in a patient with heart failure due to rapid atrial fibrillation resistant to digoxin and verapamil. |
1,613 | The implantable cardioverter defibrillator: technology, indications, and impact on cardiovascular survival. | Since the introduction of the implantable cardioverter defibrillator (ICD) for the management of patients with high risk of arrhythmic SCD, there has been increasing use of this device. Its basic promise to effectively terminate ventricular tachycardia (VT)-ventricular fibrillation (VF) has been repeatedly met. In several randomized trials, the ICD has been shown to be superior to conventional anti-arrhythmic therapy, both in patients with documented VT-VF (secondary prevention) and those with high risk such as left ventricular ejection fraction and no prior sustained VT-VF (primary prevention). In both groups, the ICD showed overall and cardiac mortality reduction. The device now can more accurately detect VT-VF and differentiate these from other arrhythmias through a series of algorithms and direct-chamber sensing. Therapy options include painless antitachycardia pacing, low-energy cardioversion, and high-energy defibrillation. The technique implant is now simple as a pacemaker with one lead attached to an active (hot) can functioning as the other electrode. Among other improvements is its weight, volume, multiprogrammability, and storage of information,dual-chamber pacing and sensing, dual-chamber defibrillation, and addition of biventricular pacing for cardiac synchronization. It is anticipated that further improvement in ICD technology will take place and the list of indications will grow. |
1,614 | Mutation in the KCNQ1 gene leading to the short QT-interval syndrome. | The electrocardiographic short QT-interval syndrome forms a distinct clinical entity presenting with a high rate of sudden death and exceptionally short QT intervals. The disorder has recently been linked to gain-of-function mutation in KCNH2. The present study demonstrates that this disorder is genetically heterogeneous and can also be caused by mutation in the KCNQ1 gene.</AbstractText>A 70-year man presented with idiopathic ventricular fibrillation. Both immediately after the episode and much later, his QT interval was abnormally short without any other physical or electrophysiological anomalies. Analysis of candidate genes identified a g919c substitution in KCNQ1 encoding the K+ channel KvLQT1. Functional studies of the KvLQT1 V307L mutant (alone or coexpressed with the wild-type channel, in the presence of IsK) revealed a pronounced shift of the half-activation potential and an acceleration of the activation kinetics leading to a gain of function in I(Ks). When introduced in a human action potential computer model, the modified biophysical parameters predicted repolarization shortening.</AbstractText>We present an alternative molecular mechanism for the short QT-interval syndrome. Functional and computational studies of the KCNQ1 V307L mutation identified in a patient with this disorder favor the association of short QT with mutation in KCNQ1.</AbstractText> |
1,615 | Efficacy of internal cardioversion for chronic atrial fibrillation in patients with and without left ventricular dysfunction. | Internal cardioversion can restore sinus rhythm with energies below 6-10 J, often without anaesthesia/sedation. We investigated its safety and short-/medium-term efficacy in patients with persistent atrial fibrillation (AF) with left ventricular dysfunction (defined as ejection fraction < or = 40%). Among 34 patients with persistent AF who agreed to receive internal cardioversion, 16 had left ventricular dysfunction and 18 did not (the groups were similar as regards age, duration of AF and pretreatment with amiodarone). Internal CV was performed delivering 3.0/3.0-ms biphasic shocks between coil catheters using a step-up protocol. Sinus rhythm was always restored. General anaesthesia (administered only when discomfort was not tolerated) was required only in 2 of the 16 (12.5%) patients with left ventricular dysfunction. The defibrillation threshold was similar in patients with and without left ventricular dysfunction (10.2+/-6.9 vs. 8.4+/-4.9 J; p=0.37). Short-term (within 72 h) AF recurrence rates in the presence and absence of left ventricular dysfunction were 19% (3/16) and 6% (1/18), respectively (p=0.51). After cardioversion, all patients received antiarrhythmic drugs (mostly amiodarone in patients with left ventricular dysfunction and class IC agents in the remainder). With mean follow-up periods of about 220 days, AF recurrence rates among patients with and without left ventricular dysfunction were 50% (8/16) and 28% (5/18), respectively (p=0.328). We conclude that even in patients with left ventricular dysfunction, internal CV is safe and effective, minimizing risks from anaesthesia. Although these patients may have a higher risk of short- or medium-term AF recurrence, 6-month maintenance of sinus rhythm is possible in about 50% of cases. |
1,616 | Novel therapeutics for treatment of long-QT syndrome and torsade de pointes. | Long-QT syndrome is a clinically and genetically heterogeneous syndrome characterized by lengthening of the QT interval and increased dispersion of the ventricular repolarization on surface electrocardiogram and a propensity to malignant ventricular arrhythmias, torsade de pointes and ventricular fibrillation, which may lead to sudden cardiac death. Long-QT syndrome mostly affects adolescents and young adults with structurally and functionally normal hearts and is caused by aberrations in potassium and sodium ion channels. Standard therapies for long-QT syndrome include correction of the underlying cause, alleviation of the precipitating factors, magnesium sulfate, isoproterenol, antiadrenergic therapy (beta-adrenergic receptor blockers, left cervicothoracic sympathectomy), cardiac pacing, and implantable cardioverter defibrillator. The potential therapies include sodium channel blockers (mexiletine, flecainide, lidocaine, pentisomide, phenytoin), potassium, potassium channel activators (nicorandil, pinacidil, cromakalim), alpha-adrenergic receptor blockers, calcium channel blockers, atropine, and protein kinase inhibitors. The purpose of this review is to outline the established therapies and update the recent advances and potential future strategies in the treatment of long-QT syndrome and torsade de pointes. |
1,617 | Intracoronary endothelin-1 infusion combined with systemic isoproterenol treatment: antagonistic arrhythmogenic effects. | Endothelin-1 secretion and sympathetic activation may play important role in cardiovascular pathophysiology. In vivo interactions between these systems are not defined. We aimed to study the electrophysiological and haemodynamic effects of simultaneous intracoronary endothelin-1 and intravenous isoproterenol infusions. 18 anaesthetised open chest dogs were studied after AV-ablation. Mean arterial blood pressure, coronary blood flow, left ventricular contractility, standard electrocardiograms, right and left ventricular epi- and endocardial monophasic action potential (MAP) signals were recorded. Intracoronary endothelin-1 (30 pmol/min) was given to Group ET (n=6), intravenous isoproterenol (0.2 microg/kg/min) to Group ISO (n=6), both endothelin-1 and isoproterenol to Group ET+ISO (n=6) for 30 min. MAP duration increased in all studied regions of Group ET, decreased in all studied regions of Group ISO and ET+ISO (control vs. maximal changes of left ventricular epicardial MAP 90% duration, Group ET: 296+/-22 vs 369+/-20 ms, p<0.05, Group ISO: 298+/-18 vs 230+/-27 ms, p<0.01, Group ET+ISO: 302+/-18 vs 231+/-10 ms, p<0.01). In Group ET, early after depolarisations (3/6), polymorphic non-sustained ventricular tachycardias (6/6), and ventricular fibrillation (3/6) could be observed. In Group ISO, monomorphic non-sustained ventricular tachycardias (5/6) and atrial fibrillation (3/6) appeared. In Group ET+ISO, mono- and polymorphic non-sustained ventricular tachycardias occurred (5/6), neither ventricular fibrillation nor atrial fibrillation developed. An additive effect of endothelin-1 and isoproterenol on left ventricular contractility was observed. Isoproterenol treatment showed antagonistic effect against endothelin-1 induced MAP duration prolongation, early after depolarisation and ventricular fibrillation formation, while endothelin-1 showed protective effect against the development of isoproterenol induced atrial fibrillation. |
1,618 | Usefulness of body surface mapping to differentiate patients with Brugada syndrome from patients with asymptomatic Brugada syndrome. | We attempted to determine the usefulness of body surface mapping (BSM) for differentiating patients with Brugada syndrome (BS) from patients with asymptomatic Brugada syndrome (ABS). Electrocardiograms (ECG) and BSM were recorded in 7 patients with BS and 35 patients with ABS. Following the administration of Ic antiarrhythmic drugs, BSM was recorded in 5 patients with BS and 16 patients with ABS. The maximum amplitudes at J0, J20, J40 and J60 were compared between the 2 groups, as were 3-dimensional maps. The maximum amplitudes at J0, J20 and J60 under control conditions were larger in patients with BS than in patients with ABS (P < 0.05). A three-dimensional map of the ST segments under control conditions in patients with BS showed a higher peak of ST elevation in the median precordium compared to that for patients with ABS. Increases in ST elevation at J20, J40 and J60 following drug administration were greater in patients with BS than in patients with ABS (P < 0.05). Evaluation of the change in amplitude of the ST segment at E5 caused by Ic drug administration was also useful for differentiating between the 2 groups. In conclusion, BSM was useful for differentiating patients with BS from those with ABS. |
1,619 | Implantable cardioverter-defibrillators in children. | Implantable cardioverter-defibrillators (ICD) have been increasingly used in adult patients for the prevention of sudden cardiac death (SCD). The usefulness and feasibility of ICD implantation in children have been less well established.</AbstractText>To analyse indications, results and safety of ICD therapy in children.</AbstractText>ICDs were implanted in seven children, aged from 6 to 17 years. All patients underwent cardiological evaluation which included analysis of medical history, physical examination, chest X-ray, standard ECG, 24-hour Holter ECG monitoring and echocardiography.</AbstractText>In five children devices were implanted due to aborted sudden death (ventricular fibrillation) whereas in the remaining two - as a primary prevention of SCD. Three children had hypertrophic cardiomyopathy, one - dilated cardiomyopathy, one - mitral valve prolapse and QT prolongation, one - congenital long QT syndrome and the remaining patient - idiopathic ventricular tachycardia. Single-chamber devices were implanted in six children, and dual-chamber system - in one patient. In all patients endocardial leads were implanted and ICD pocket was formed under the greater pectoral muscle. During follow-up ranging between four months to 5.4 years, four children developed ventricular fibrillation or ventricular tachycardia which were terminated by appropriate ICD discharges.</AbstractText>1. ICD implantation in children is effective in the prevention of SCD. 2. In our population, the most frequent indications for device implantation were life-threatening ventricular arrhythmias occurring in patients with cardiomyopathy. 3. Cardiac arrest due to ventricular fibrillation may occur in children without a history of aborted SCD. 4. ICD implantation in children is feasible and safe.</AbstractText> |
1,620 | Risk factors of atrial fibrillation in patients with Wolff-Parkinson-White syndrome. | Atrial fibrillation (AF) in patients with WPW syndrome may be a life-threatening arrhythmia.</AbstractText>To identify risk factors of AF and their prognostic significance in patients with WPW syndrome.</AbstractText>Clinical and electrophysiological parameters of 239 patients with WPW syndrome, who underwent successful RF ablation, were analysed using logistic regression and multivariate analysis. One hundred eight patients had no history of AF whereas the remaining 81 patients had previous spontaneous AF episodes. Long-term follow-up data (mean 29+/-23 months, range 1-99 months) were available in 136 patients (87 without AF and 49 with AF).</AbstractText>Patients with AF were significantly older, more frequently of male gender and had more often a history of syncope than patients without AF. There were two peaks of AF occurrence - in the third and in the fifth decade of life. Fourteen patients had a history of ventricular fibrillation - 11 patients with AF vs 3 patients without AF (p=0.0016). Patients with a history of AF were more prone to AF induced during electrophysiological study and had less frequently concealed accessory pathways.</AbstractText>Age, gender and a history of syncope are the independent risk factors of AF in patients with WPW syndrome. Anterograde conduction via accessory pathway is of major importance in the development of AF. RF ablation of an accessory pathway should be performed early because the risk of the procedure is small and there is an increasing risk of AF with ageing.</AbstractText> |
1,621 | Challenges in improving prognosis and therapy: the Ongoing Telmisartan Alone and in Combination with Ramipril Global End point Trial programme. | Hypertension is one of the most important modifiable risk factors for cardiovascular pathology, such as atherosclerosis and cardiac left ventricular hypertrophy, including acute events such as stroke and myocardial infarction (MI). In particular, the risk of ischaemic and haemorrhagic stroke is directly and continuously related to high blood pressure levels. The renin-angiotensin system (RAS) plays an important role in volume homeostasis and blood pressure regulation. It also helps to prevent cell and organ damage from ischaemia during acute volume loss. However, angiotensin-II (A-II)--the main effector peptide of the RAS--also exerts a number of pathological effects, which are mediated by the AT 1 receptor. The Ongoing Telmisartan Alone and in Combination with Ramipril Global End point Trial (ONTARGET) programme consists of two parallel trials where ONTARGET as a large, long-term study compares the efficacy of the angiotensin-receptor antagonist, telmisartan, the renin-angiotensin-converting enzyme (ACE) inhibitor, ramipril and combination therapy with telmisartan plus ramipril for reducing cardiovascular and cerebral risk. Telmisartan, due to its long duration of action, compares favourably with other angiotensin-receptor antagonists. In the Heart Outcomes Prevention Evaluation (HOPE) study, ramipril was shown to reduce the risk for MI and other cardiovascular events in patients at high risk for pathological cardiac events, but without heart failure or a low ejection fraction. The cardiovascular outcomes of high-risk patients using the same criteria as those of the HOPE study will be assessed in both trials. TRANSCEND differs from ONTARGET in that this trial will enrol patients who do not tolerate ACE inhibitors. This parallel study will therefore be able to compare telmisartan and placebo treatment. Both ONTARGET and TRANSCEND trials feature the same primary composite end point: death caused by cardiovascular disease, acute MI, stroke and hospitalisation because of congestive heart failure. The secondary end points will focus on reductions in the development of Type 2 diabetes mellitus, nephropathy, cognitive decrease and dementia as well as atrial fibrillation. |
1,622 | Novel antithrombotic therapies for the prevention of stroke in patients with atrial fibrillation. | Atrial fibrillation (AF), the most common type of arrhythmia in adults, is a major risk factor for stroke. The prevalence of AF increases with age, occurring in 1% of persons <60 years of age and in almost 10% of those >80 years of age. Recent studies show that treatment strategies that combine control of ventricular rate with antithrombotic therapy are as effective as strategies aimed at restoring sinus rhythm. Current antithrombotic therapy regimens in patients with AF involve chronic anticoagulation with dose-adjusted vitamin K antagonists unless patients have a contraindication to these agents or are at low risk for stroke. Patients with AF at low risk for stroke may benefit from aspirin. Although vitamin K antagonists are effective, their use is problematic, highlighting the need for new antithrombotic strategies. This article will (a) provide an overview of the clinical trials that form the basis for current antithrombotic guidelines in patients with AF, (b) highlight the limitations of current antithrombotic drugs used for stroke prevention, (c) briefly review the pharmacology of new antithrombotic drugs under evaluation in AF, (d) describe ongoing trials with new antiplatelet therapies and idraparinux, and completed studies with ximelagatran in patients with AF, and (e) provide clinical perspective into the potential role of new antithrombotic drugs in AF. |
1,623 | Epidemiology and management of new-onset atrial fibrillation. | Atrial fibrillation (AF) is a common acute or chronic cardiac disorder that can result in significant morbidity and mortality. Its incidence in the United States is increasing. Projections suggest that more than 5.6 million Americans (50% of whom will be > or =80 years of age) will have AF by 2050. The American College of Cardiology, American Heart Association, and the European Society of Cardiology define AF as a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function. On an electrocardiogram, AF is characterized by the replacement of P waves by rapid oscillations or fibrillatory waves that vary in size, shape, and timing. Evidence suggests that histological changes exist in the atria of patients with AF, however, it is not known if these changes are a cause or a consequence of AF. Although the fundamental mechanism underlying the disorder is not known, clinical identifying factors are associated with the condition. These may be divided into noncardiac (thyrotoxicosis, alcohol use, electrolyte imbalance, certain pharmacologic and recreational drugs) and cardiac causes (any cause of enlarged left atrium, poor ventricular function, heart surgery). The principles of treatment for this condition are to stabilize the patient hemodynamically, simultaneously determine whether a reversible cause of the AF exists, control the patient's heart rate, determine whether the patient should be cardioverted or maintained in AF, and then develop strategies to prevent the most important complications of stroke. This article will describe in detail the acute management of AF as well as its epidemiology. |
1,624 | [EBM of cerebral infarction: message from mega-studies]. | A meta-analysis by the Antithrombotic Trialists' Collaboration showed significant reduction of vascular events including stroke. MI, and vascular death by antiplatelet therapy in high risk patients with obstructive vascular disease. Low dose aspirin of 75 to 150 mg was most effective and its very low dose below 75 mg was not proven effective. Cilostazol significantly reduced the risk of recurrence in Japanese patients with ischemic stroke, mostly lacunar stroke. Large randomized controlled trials (RCTs) such as MATCH, ACTIVE, and CHARISMA are ongoing to see an effect of aspirin plus clopidogrel. Among patients with non-valvular atrial fibrillation (NVAF), warfarin is recommended in patients at age over 75 years, and those with history of stroke or TIA, hypertension, congestive heart failure, diabetes or coronary heart disease, while aspirin can be alternative in patients without any of these risk factors of stroke. Target INR of 2.0 to 3.0 is recommended in these NVAF patients, although lower INR of 1.6 to 2.5 is recommended to avoid hemorrhagic stroke in elderly patients with NVAF. SPORTIF was conducted to compare ximelagatran, an oral thrombin inhibitor, with warfarin in NVAF patients with risk factors, and the result showed a comparable efficacy and safety of ximelagatran. WARSS did not show any efficacy of warfarin over aspirin in any subtypes of ischemic stroke patients without NVAF, acute MI, left ventricular thrombi, or prosthetic heart valve. PICSS, a substudy of WARSS, also did not show any efficacy of warfarin over aspirin in stroke patients with patent foramen ovale (PFO), although warfarin might be recommended in PFO patients with deep vein thrombosis. |
1,625 | Intravenous nicorandil can reduce the occurrence of ventricular fibrillation and QT dispersion in patients with successful coronary angioplasty in acute myocardial infarction. | Because nicorandil, a potassium channel opener, has a cardioprotective effect and attenuates reperfusion injury in patients with acute myocardial infarction (AMI), intravenous nicorandil should reduce arrhythmic mortality and QT dispersion in patients with AMI.</AbstractText>The purpose of this study was to evaluate whether intravenous nicorandil reduces the occurrence of ventricular fibrillation and QT dispersion in patients with successful coronary angioplasty in AMI.</AbstractText>A historical cohort study on the effect of nicorandil on ventricular fibrillation and QT dispersion was conducted. Eighty-three patients with AMI who underwent successful percutaneous transluminal coronary angioplasty (PTCA) were enrolled. The patients were divided into two groups: nicorandil (n=46) and control group (n=37). Nicorandil was injected at 4 mg/h continuously from admission to 48 h after PTCA in the nicorandil group. QT dispersion was measured before, immediately after, 24 h after and 48 h after PTCA.</AbstractText>Ventricular fibrillation was observed in three patients in the control group, but none was observed in the nicorandil group. QT dispersion in the nicorandil group was shorter than that in the control group 48 h after PTCA (QT dispersion was 23.2+/-16.1 ms and 33.4+/-24.0 ms, respectively, P<0.05). There was a significant difference between the two groups in time course after the onset of AMI (P<0.05).</AbstractText>Because intravenous nicorandil reduces the occurrence of ventricular fibrillation and QT dispersion in patients with successful coronary angioplasty in AMI, it would prevent the occurrence of cardiac events after successful PTCA for AMI.</AbstractText> |
1,626 | Cardiac resynchronization therapy: device-based medicine for heart failure. | Cardiac resynchronization therapy (CRT) or biventricular pacing is a novel adjunctive therapy for patients with advanced heart failure (HF). Many patients with severe HF have a left bundle branch block or an intraventricular conduction delay, with up to 25% of patients with a QRS > 120 ms, resulting in significant left ventricular (LV) dyssynchrony and a high mortality rate. The efficacy of CRT is based on the reduction in the conduction delay between the two ventricles and optimization of the ejection fraction, decrement in mitral regurgitation, LV remodeling, thus resulting in symptom improvement. Cardiac resynchronization therapy can be achieved both transvenously using a coronary sinus branch, or epicardially. Clinical trials have demonstrated a significant improvement in the NYHA class and the exercise capacity as well as a marked reduction in the hospitalization rate. More recently, the COMPANION trial showed a 43% reduction in a composite endpoint of all-cause mortality and hospitalization in the group receiving a CRT device in combination with an implantable cardiac defibrillator (ICD). Thus, management of patients with reduced LV function, wide QRS, and symptomatic refractory HF, despite optimal drug therapy, should include CRT as an option. The adjunct of an ICD combined with CRT should be considered if the LV ejection fraction (ischemic cardiomyopathy) is <30%. There are still significant unanswered questions regarding the nonresponder population and the role of tissue Doppler imaging techniques, the impact of CRT on total mortality and CRT in dilated cardiomyopathy or chronic atrial fibrillation. The use CRT postoperatively or at time of cardiac surgery, as well as new epicardial approaches using a thoracoscopic approach or robotically assisted surgery in patients not suitable for coronary vein leads are challenging topics to address in the years to come. |
1,627 | [Subpectoral implantable cardioverter defibrillator implantation in a 20 kg-weighted child]. | An 11-year-old boy (weight 20 kg, height 124 cm), who was survived from ventricular fibrillation due to hypertrophic cardiomyopathy, admitted to our institution for implantable cardioveter defibrillator (ICD) implantation. We implanted a transvenous single coil lead and a device (Medtronic model 6943, GEM II VR 7229 Cx) in the subpectoral pocket. We selected this system because of less restriction on normal cardiac function, low operative morbidity, and expectation of long-term defibrillation threshold stability. Subpectoral implantation is cosmetically acceptable comparing with abdominal area. Lead insertion by cut-down technique is feasible and recommended to avoid lead-related complications. ICDs are infrequently used in pediatric patients and prospective study with long-term follow-up will be required to ascertain the prognosis for young survivors from sudden cardiac death. |
1,628 | Utility of implantable cardioverter defibrillator electrograms to estimate repolarization alternans preceding a tachyarrhythmic event. | Electrical alternans is a pattern of variation in the shape of the ECG waveform that appears on an every-other-beat basis. In humans, alternation in ventricular repolarization, namely, repolarization alternans, has been associated with increased vulnerability to ventricular tachycardia/ventricular fibrillation and sudden cardiac death. This study investigates the utility of implantable cardioverter defibrillator electrograms to estimate repolarization alternans preceding a tachyarrhythmic event. It is demonstrated that microvolt-level repolarization alternans is present prior to an arrhythmic event, and one can record low-amplitude-noise signals that can be used to obtain reliable estimates of repolarization alternans. This study eventually may lead to new methods that would prevent the onset of malignant tachyarrhythmias. |
1,629 | Parasympathetic cardiac nerve stimulation with implanted coronary sinus lead. | A patient with drug-refractory paroxysmal atrial fibrillation associated with rapid ventricular rate underwent biatrial pacemaker implantation. During elective replacement of the pacemaker, a significant voltage- and frequency-dependent decrease in ventricular rate was achieved by high-frequency electrical stimulation (17 Hz) of parasympathetic cardiac nerves innervating the AV node with the implanted bipolar coronary sinus electrode. The negative dromotropic effect of parasympathetic stimulation was eliminated by intravenous administration of 1-mg atropine. |
1,630 | Improvement of defibrillation efficacy with preshock synchronized pacing. | We previously demonstrated that wavefront synchronization by spatiotemporal excitable gap pacing (Sync P) is effective at facilitating spontaneous termination of ventricular fibrillation (VF). Therefore, we hypothesized that a spatiotemporally controlled defibrillation (STCD) strategy using defibrillation shocks preceded by Sync P can improve defibrillation efficacy.</AbstractText>We explored the STCD effects in 13 isolated rabbit hearts. During VF, a low-voltage gradient (LVG) area was synchronized by Sync P for 0.92 second. For Sync P, optical action potentials (OAPs) adjacent to four pacing electrodes (10 mm apart) were monitored. When one of the electrodes was in the excitable gap, a 5-mA current was administered from all electrodes. A shock was delivered 23 ms after the excitable gap when the LVG area was unexcitable. The effects of STCD was compared to random shocks (C) by evaluating the defibrillation threshold 50% (DFT(50); n = 35 for each) and preshock coupling intervals (n = 208 for STCD, n = 172 for C). Results were as follows. (1) Sync P caused wavefront synchronization as indicated by a decreased number of phase singularity points (P < 0.0001) and reduced spatial dispersion of VF cycle length (P < 0.01). (2) STCD decreased DFT(50) by 10.3% (P < 0.05). (3) The successful shocks showed shorter preshock coupling intervals (CI; P < 0.05) and a higher proportion of unexcitable shock at the LVG area (P < 0.001) than failed shocks. STCD showed shorter CIs (P < 0.05) and a higher unexcitable shock rate at LVG area (P < 0.05) than C.</AbstractText>STCD improves defibrillation efficacy by synchronizing VF activations and increasing probability of shock delivery to the unexcitable LVG area.</AbstractText> |
1,631 | Reversal of electrical remodeling after cardioversion of persistent atrial fibrillation. | In animals, atrial fibrillation results in reversible atrial electrical remodeling manifested as shortening of the atrial effective refractory period, slowing of intra-atrial conduction, and prolongation of sinus node recovery time. There is limited information on changes in these parameters after cardioversion in patients with persistent atrial fibrillation.</AbstractText>Thirty-eight patients who had been in atrial fibrillation for 1 to 12 months underwent electrophysiologic testing 10 minutes and 1 hour after cardioversion. At 1 week, 19 patients still in sinus rhythm returned for repeat testing. Reverse remodeling of the effective refractory period was not uniform across the three atrial sites tested. At the lateral right atrium, there was a highly significant increase in the effective refractory period between 10 minutes and 1 hour after cardioversion (drive cycle length 400 ms: 204 +/- 17 ms vs 211 +/- 20 ms, drive cycle length 550 ms: 213 +/- 18 ms vs 219 +/- 23 ms, P < 0.001). The effective refractory period at the coronary sinus and distal coronary sinus did not change in the first hour but had increased by 1 week. The corrected sinus node recovery time did not change in the first hour but was shorter at 1 week (606 +/- 311 ms vs 408 +/- 160 ms, P = 0.009). P wave duration also was shorter at 1 week (135 +/- 18 ms vs 129 +/- 13 ms, P = 0.04) consistent with increasing atrial conduction velocity.</AbstractText>The atrial effective refractory period increases, sinus node function improves, and atrial conduction velocity goes up in the first week after cardioversion of long-standing atrial fibrillation in humans. Reverse electrical remodeling of the effective refractory period occurs at different rates in different regions of the atrium.</AbstractText> |
1,632 | Inhibition of cardiac HERG currents by the DNA topoisomerase II inhibitor amsacrine: mode of action. | 1 The topoisomerase II inhibitor amsacrine is used in the treatment of acute myelogenous leukemia. Although most anticancer drugs are believed not to cause acquired long QT syndrome (LQTS), concerns have been raised by reports of QT interval prolongation, ventricular fibrillation and death associated with amsacrine treatment. Since blockade of cardiac human ether-a-go-go-related gene (HERG) potassium currents is an important cause of acquired LQTS, we investigated the acute effects of amsacrine on cloned HERG channels to determine the electrophysiological basis for its proarrhythmic potential. 2 HERG channels were heterologously expressed in human HEK 293 cells and Xenopus laevis oocytes, and the respective potassium currents were recorded using patch-clamp and two-microelectrode voltage-clamp electrophysiology. 3 Amsacrine blocked HERG currents in HEK 293 cells and Xenopus oocytes in a concentration-dependent manner, with IC50 values of 209.4 nm and 2.0 microm, respectively. 4 HERG channels were primarily blocked in the open and inactivated states, and no additional voltage dependence was observed. Amsacrine caused a negative shift in the voltage dependence of both activation (-7.6 mV) and inactivation (-7.6 mV). HERG current block by amsacrine was not frequency dependent. 5 The S6 domain mutations Y652A and F656A attenuated (Y652A) or abolished (F656A, Y652A/F656A) HERG current blockade, indicating that amsacrine binding requires a common drug receptor within the pore-S6 region. 6 In conclusion, these data demonstrate that the anticancer drug amsacrine is an antagonist of cloned HERG potassium channels, providing a molecular mechanism for the previously reported QTc interval prolongation during clinical administration of amsacrine. |
1,633 | Adding sodium and calcium ions to the contrast medium iodixanol reduced the risk of ventricular fibrillation during perfusion of the left coronary artery in pigs: effects of electrolytes, viscosity, and chemotoxicity of an isotonic perfusate. | The effects of electrolytes, viscosity, and chemotoxicity of a plasma-isotonic iodine contrast medium iodixanol were compared with regard to its propensity to cause ventricular fibrillation (VF).</AbstractText>The left coronary artery of pigs was perfused with five isotonic solutions: iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2, Iod 320+Mann (iodixanol 320 mg I/mL + 50 mmol/L mannitol), Mann+Na/Ca (240 mmol/L mannitol with 19 mmol/L NaCl + 0.3 mmol/L CaCl2), Mann (275 mmol/L mannitol) and Ringer. The first two solutions have at 37 degrees C a viscosity of approximately 13 mPa x s while the others have a viscosity < 1 mPa x s. In eight pigs, each test solution was injected twice into the left coronary artery in random order for 10 seconds (injection volume, 20 mL). In 15 pigs, each of the solutions was injected in random order for 11-40 seconds through the end-hole of a wedged 5F balloon catheter in left coronary artery. Injection rate was 0.5 mL/sec until VF occurred. If VF occurred, injection was stopped and the heart was defibrillated. If VF did not occur, the perfusion period was 40 seconds.</AbstractText>The 10-second perfusions caused no VF. The 40-second perfusions with iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2 or Ringer caused no VF (0%). Iod 320+Mann caused nine VF (60%) after 35 +/- 4 seconds (SEM). Mann+Na/Ca caused 14 VF (93%) after 30 +/- 2 seconds. Mann caused 15 VF (100%) after 24 +/- 2 seconds. Iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2 and Ringer caused fewer VF than all other solutions (P < .05-.001). Iod 320+Mann caused fewer VF than Mann (P < .05). Iod 320+Mann caused VF later than Mann+Na/Ca or Mann (P < .02 and P < .01). Mann+Na/Ca caused VF later than Mann (P < .05).</AbstractText>The results fit with a concept that VF starts when the electrolyte composition of the interstitial fluid in the myocardium is sufficiently nonphysiologic. The more physiologic the electrolyte composition of the perfusion fluid, and the higher its viscosity, the slower the composition of the interstitial fluid will be changed, and VF will occur later (or not at all).</AbstractText> |
1,634 | Incidence and electrophysiological characteristics of spontaneous ventricular tachyarrhythmias in high risk coronary patients and prophylactic implantation of a defibrillator. | To assess the incidence and electrophysiological characteristics of spontaneous ventricular tachyarrhythmias after implantable cardioverter-defibrillator (ICD) implantation for primary prevention.</AbstractText>Prospective observational study.</AbstractText>41 consecutive patients, who fulfilled MADIT (multicenter automatic defibrillator implantation trial) I criteria, except for suppressibility by procainamide, and who received a prophylactic ICD.</AbstractText>Subpectoral implantation of an ICD.</AbstractText>Incidence of ventricular tachyarrhythmias and their electrophysiological characteristics with respect to timing of the arrhythmia, tachyarrhythmia cycle length, mode of termination, and clinical relevance.</AbstractText>During a mean (SD) follow up of 30 (21) months 18 of 41 (43.9%) patients experienced 142 appropriate ICD treatments. The mean (SD) time to first event was 9.6 (15.1) months. One patient had ventricular fibrillation (VF), 12 patients ventricular tachycardia (VT), and five both VT and VF. The mean (SD) cycle length of monomorphic VT was 306 (42) ms. Of 142 episodes, 117 (82.3%) were terminated by antitachycardia pacing and another 25 (17.6%) by ICD discharges. Cumulative survival of hypothetical death, defined as treated VT with a cycle length < 260 ms or VF, was 83.2% after one year and 78.4% after two years.</AbstractText>Patients with a left ventricular ejection fraction < 35%, a history of myocardial infarction, non-sustained VT, and inducible VT/VF are at high risk of VT/VF early after implantation. Therefore, implantation of a tiered treatment defibrillator seems to be justified.</AbstractText> |
1,635 | Incidence of atrial fibrillation and thromboembolism in a randomised trial of atrial versus dual chamber pacing in 177 patients with sick sinus syndrome. | To analyse the occurrence of atrial fibrillation (AF) and thromboembolism in a randomised comparison of rate adaptive single chamber atrial pacing (AAIR) and dual chamber pacing (DDDR) in patients with sick sinus syndrome and normal atrioventricular (AV) conduction, in which left atrial dilatation and decreased left ventricular fractional shortening had been observed in the DDDR group.</AbstractText>177 consecutive patients with sick sinus syndrome (mean (SD) age 74 (9) years, 104 women) were randomly assigned to treatment with one of three pacemakers: AAIR (n = 54), DDDR with a short rate adaptive AV delay (n = 60) (DDDR-s); or DDDR with a fixed long AV delay (n = 63) (DDDR-l). Analysis was intention to treat.</AbstractText>Mean follow up was 2.9 (1.1) years. AF at one or more ambulatory visits was significantly less common in the AAIR group (4 (7.4%) v 14 (23.3%) in the DDDR-s group v 11 (17.5%) in the DDDR-l group; p = 0.03, log rank test). The risk of developing AF in the AAIR group compared with the DDDR-s group was significantly decreased after adjustment for brady-tachy syndrome in a Cox regression analysis (relative risk 0.27, 95% confidence interval (CI) 0.09 to 0.83, p = 0.02). The benefit of AAIR was highest among patients with brady-tachy syndrome. Brady-tachy syndrome and a thromboembolic event before pacemaker implantation were independent predictors of thromboembolism during follow up (relative risk 7.5, 95% CI 1.6 to 36.2, p = 0.01, and relative risk 4.7, 95% CI 1.2 to 17.9, p = 0.02, respectively).</AbstractText>During a mean follow up of 2.9 years AAIR was associated with significantly less AF. The beneficial effect of AAIR was still significant after adjustment for brady-tachy syndrome. Brady-tachy syndrome was associated with an increased risk of thromboembolism.</AbstractText> |
1,636 | Hydroquinidine therapy in Brugada syndrome. | We sought to assess hydroquinidine (HQ) efficacy in selected patients with Brugada syndrome (BrS).</AbstractText>Management of asymptomatic patients with BrS and inducible arrhythmias remains a key issue. Effectiveness of class Ia antiarrhythmic drugs, which inhibit the potassium transient outward current of the action potential, has been suggested in BrS.</AbstractText>From a cohort of 106 BrS patients, we studied 35 who received HQ (32 men; mean age 48 +/- 11 years). Patients had asymptomatic BrS and inducible arrhythmia (n = 31) or multiple appropriate shocks from an implantable cardioverter-defibrillator (ICD) (n = 4). Asymptomatic patients with inducible arrhythmia underwent electrophysiologic (EP)-guided therapy. When ventricular tachycardia (VT)/ventricular fibrillation (VF) inducibility was not prevented, or in case of HQ intolerance, an ICD was placed.</AbstractText>Hydroquinidine prevented VT/VF inducibility in 76% of asymptomatic patients who underwent EP-guided therapy. Syncope occurred in two of the 21 patients who received long-term (17 +/- 13 months) HQ therapy (1 syncope associated with QT interval prolongation and 1 unexplained syncope associated with probable noncompliance). In asymptomatic patients who received an ICD (n = 10), one appropriate shock occurred during a follow-up period of 13 +/- 8 months. In patients with multiple ICD shocks, HQ prevented VT/VF recurrence in all cases during a mean follow-up of 14 +/- 8 months.</AbstractText>Hydroquinidine therapy prevented VT/VF inducibility in 76% of asymptomatic patients with BrS and inducible arrhythmia, as well as VT/VF recurrence in all BrS patients with multiple ICD shocks. These preliminary data suggest that preventive treatment by HQ may be an alternative strategy to ICD placement in asymptomatic patients with BrS and inducible arrhythmia.</AbstractText> |
1,637 | Sustained ventricular tachycardia or fibrillation in the cardiac catheterization laboratory among patients receiving primary percutaneous coronary intervention: incidence, predictors, and outcomes. | We sought to evaluate the incidence, predictors, and outcomes of ventricular tachycardia and/or ventricular fibrillation (VT/VF) in the cardiac catheterization laboratory among patients undergoing primary percutaneous coronary intervention (PCI).</AbstractText>Although VT/VF has been known to occur during primary PCI, the current data do not identify patients at risk for these arrhythmias or the outcomes of such patients.</AbstractText>We evaluated 3065 patients enrolled in the Primary Angioplasty in Myocardial Infarction (PAMI) trials, who underwent primary PCI to evaluate the associations of VT/VF and the influence of these arrhythmias on in-hospital and one-year outcomes.</AbstractText>In patients undergoing primary PCI, VT/VF occurred in 133 (4.3%). Multivariate analysis identified the following as independent correlates of VT/VF: smoking (odds ratio [OR] 1.95, 95% confidence interval [CI] 1.26 to 3.02), lack of preprocedural beta-blockers (OR 2.34, 95% CI 1.35 to 4.07), time from symptom onset to emergency room of <or=180 min (OR 2.63, 95% CI 1.42 to 4.89), initial Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 (OR 2.06, 95% CI 1.23 to 3.47), and right coronary artery-related infarct (OR 1.93, 95% CI 1.25 to 2.99). Although patients with VT/VF had a higher incidence of bradyarrhythmias, hypotension, cardiopulmonary resuscitation, and endotracheal intubation in the catheterization laboratory, their in-hospital and one-year adverse outcomes were similar to those of the cohort without these arrhythmias.</AbstractText>Our findings suggest that the incidence of VT/VF during primary PCI is low, indicating that these arrhythmias do not influence PCI success or in-hospital or one-year outcomes. Our data further help identify patients at risk of VT/VF during primary PCI and suggest that pretreatment with beta-blockers should be strongly considered to reduce these arrhythmias.</AbstractText> |
1,638 | Concomitant anti-arrhythmic surgery, using irrigated cooled-tip radiofrequency ablation, to treat permanent atrial fibrillation in CABG patients: expansion of the indication? | The effectiveness of a concomitant anti-arrhythmic surgical procedure in coronary artery bypass grafting (CABG) patients with permanent atrial fibrillation (AF) was evaluated.</AbstractText>This prospective study included 36 CABG patients, who had a concomitant anti-arrhythmic procedure using irrigated cooled-tip radiofrequency ablation. Follow-up included a 24 h EKG and ultrasound examination at 3, 6, 12 months.</AbstractText>Mean (SD) age was 68.7 years (8.0), left atrial diameter 44.9 mm (6.7), preoperative duration of AF 67 months (73), left ventricular ejection fraction 54% (14), euroscore 5.5 (2.6), number of distal anastomoses 3.3 (1.2), aortic cross-clamp time 90 (19)min, extracorporeal bypass time 156 (38)min. Thirty-day mortality was 2.8% (1/36). Mean (SD) follow-up was 25.3 months (17.9). Cumulative survival rates (SE) at 12 and 24 months were 0.94 (0.04) and 0.90 (0.06). Cumulative postoperative sinus rhythm (SR) rates (SE) at 6 and 12 months were 0.60 (0.08) and 0.75 (0.08). Restored bi-atrial contraction occurred in 73% (19/26) of all SR patients. As a consequence coumadine was stopped, after the 6th postoperative month, in 76% (16/21) in this subset of patients, corresponding with 44% (16/36) of all study group patients. One patient experienced a sick sinus syndrome 12 months postoperatively, for which a DDD pacemaker was implanted. Three out of five patients with a preexistent VVI pacemaker regained a stable postoperative SR with bi-atrial contraction, obviating the need of any pacemaker support.</AbstractText> |
1,639 | Ischemic postconditioning: brief ischemia during reperfusion converts persistent ventricular fibrillation into regular rhythm. | Brief episodes of myocardial ischemia-reperfusion employed during reperfusion after a prolonged ischemic insult may attenuate the total ischemia-reperfusion injury. This phenomenon has been termed ischemic postconditioning. In the present study, we studied the possible effect of postconditioning on persistent reperfusion-induced ventricular fibrillation (VF) in the isolated rat heart model.</AbstractText>Isolated Langendorff-perfused rat hearts (n = 46) were subjected to 30 min of regional ischemia and reperfusion. The hearts with persistent VF (n = 11) present after 15 min of reperfusion were then randomly assigned into one of the two groups: (1) control hearts (n = 6) in which perfusion was continued without intervention; (2) postconditioned hearts (n = 5) subjected to 2 min of global ischemia followed by reperfusion. Left ventricular pressures, heart rate, coronary flow, and electrogram were monitored throughout the experiment.</AbstractText>Conversion of VF into regular rhythm was observed in all hearts subjected to postconditioning. Regular beating was maintained by all postconditioned hearts during the subsequent reperfusion. None of the hearts in the control group had normal rhythm at the end of the experiment. At the end of reperfusion, the left ventricular developed pressure was lower in beating postconditioned hearts compared to the hearts that did not develop persistent VF.</AbstractText>Ischemic postconditioning possesses strong antiarrhythmic effect against persistent reperfusion-induced tachyarrhythmias. Postconditioning may be an interesting, novel adjunct strategy to protect the heart.</AbstractText> |
1,640 | Role of carvedilol in atrial fibrillation: insights from clinical trials. | Atrial fibrillation affects approximately 2 million people in the United States and is a common comorbidity among patients with heart failure. Clinical studies indicate that the benefits of the beta-blocker carvedilol in patients with heart failure extend to patients with heart failure complicated by atrial fibrillation. The results of the Carvedilol in Atrial Fibrillation Evaluation (CAFE) trial provide support that carvedilol has incremental benefit when added to digoxin for the management of atrial fibrillation in patients with heart failure. Additional recent studies suggest that carvedilol may be useful in managing postsurgical atrial fibrillation and also may prevent recurrence of atrial fibrillation among patients who undergo cardioversion. |
1,641 | Effect of biventricular pacing therapy in patients with dilated cardiomyopathy with severe congestive heart failure. | Biventricular pacing (BVP) therapy has recently emerged as an effective treatment for patients with moderate to severe congestive heart failure (CHF) and ventricular asynchrony all over the world. However, this therapy is not yet available in Japan. We evaluated the effects of BVP in patients with severe CHF due to dilated cardiomyopathy (DCM).</AbstractText>Four patients with medically refractory severe CHF due to DCM in New York Heart Association functional class III or IV heart failure underwent BVP therapy. We combined the implantation of the left ventricular (LV) epicardial lead via small thoracotomy following right atrial and ventricular intravenous leads under general anesthesia. We evaluated to determine whether improvements of ventricular function, ventricular size, mitral regurgitation, functional status, frequency of hospitalization, and quality of life were associated with BVP therapy.</AbstractText>BVP improved LV systolic function, decreased LV size and mitral regurgitation, and shortened prolonged QRS interval. The patients' symptoms, exercise tolerance, frequency of hospitalization, and quality of life were also dramatically improved by BVP. Furthermore, combination of BVP and oral administration of amiodarone significantly prevented recurrence of ventricular tachycardia and paroxysmal atrial fibrillation, and maintained sinus rhythm for a long period.</AbstractText>In view of these findings, BVP therapy may contribute to the development of new therapeutic method for patients with severe CHF due to DCM.</AbstractText> |
1,642 | [Catheter ablation of atrial flutter and atrial fibrillation]. | Within the past 20 years, refinements in electrophysiologic mapping techniques have provided a better understanding of the pathophysiology of atrial flutter and atrial fibrillation (AF), which resulted in the development of catheter ablation techniques for this arrhythmias. Nowadays, catheter ablation has become the first line treatment of recurrent symptomatic or hemodynamically significant atrial flutter. In contrast, catheter ablation of AF is still an investigational procedure and should be restricted to patients with symptomatic AF who have been refractory to multiple antiarrhythmic drugs. In symptomatic patients with AF and an uncontrolled ventricular rate who have failed treatment with several antiarrhythmic drugs and who do not fit for primary catheter ablation of AF atrioventricular junction ablation with prior pacemaker implantation is recommended. |
1,643 | Assessment of left atrial volume by contrast enhanced magnetic resonance angiography. | Left atrial (LA) volume is associated with cardiovascular morbidity, particularly atrial fibrillation. Contrast-enhanced magnetic resonance angiography (CE-MRA) visualizes the LA, but the validity of LA volume measurements using this technique has not been evaluated. We performed CE-MRA and cine magnetic resonance (MR) in 18 consecutive patients referred for CE-MRA prior to atrial fibrillation ablation. The CE-MRA LA volumes were compared to cine MR LA volumes at the maximal LA size and at LA end-diastole using linear regression and limits of agreement analysis. The mean cine MR LA volume was 118 +/- 39 mL at maximal LA size and 91 +/- 38 mL at LA end-diastole. Left atrial volume determined by CE-MRA was 93 +/- 38 mL. Although the CE-MRA LA volume had a strong correlation with the maximal cine MR LA volume (R2 = 0.86, p < 0.001), the 95% limits of agreement were relatively wide (-54 to 3 mL). The cine MR LA end-diastolic and CE-MRA LA volumes were more closely correlated (R2 = 0.98, p < 0.001) with narrow 95% limits of agreement (-8 to 11 mL). The CE-MRA LA volumes correspond most closely to LA end-diastolic cine MR LA volumes and may be a useful measure of LA size. |
1,644 | Effectiveness of sotalol treatment in symptomatic Brugada syndrome. | We describe a 53-year-old man with recurrent syncopal events and a malignant family history who was treated for 13 years with sotalol drug therapy with no further occurrence of Brugada syndrome symptoms. Genetic testing revealed that he carried a Brugada syndrome sodium channel SCN5A mutation (4189delT). This finding suggests that sotalol may be of therapeutic benefit in such patients. |
1,645 | Optimal dosing of dobutamine for treating post-resuscitation left ventricular dysfunction. | This study was designed to determine the optimal dose of dobutamine in the treatment of post-resuscitation left ventricular dysfunction.</AbstractText>Global left ventricular dysfunction following successful resuscitation from prolonged, ventricular fibrillation cardiac arrest, negatively impacts long-term survival. Dobutamine can overcome this global myocardial stunning. Previous data indicate a dose of 10 mcg/kgmin improves systolic and diastolic function, but markedly increases the heart rate.</AbstractText>Twenty swine (24 +/- 0.4 kg) were randomized to one of four doses (0, 2, 5, and 7.5 mcg/kgmin) of dobutamine for the treatment of post-resuscitation myocardial dysfunction following 12.5 min of untreated ventricular fibrillation cardiac arrest. Cardiac function was measured at pre-arrest baseline and serially for 6 h post-resuscitation. Left ventricular function was evaluated by contrast ventriculograms, left ventricular pressures, +dP/dt, Tau, -dP/dt, and cardiac output. Myocardial oxygen consumption and myocardial blood flow were measured to assess the functional significance of any dobutamine-mediated heart rate responses.</AbstractText>Left ventricular dysfunction was evident at 25 min and peaked 4 h post-resuscitation. Significant (P < 0.05) improvements in ventricular systolic (EF, CO) and diastolic (LVEDP, Tau) function were evident within minutes of dobutamine initiation and persisted at 6h for the 5 and 7.5 mcg/kgmin groups. Tachycardia manifested with all dobutamine doses, but only affected myocardial oxygen consumption significantly (P < 0.05) at the highest dose (7.5 mcg/kgmin).</AbstractText>Dobutamine at 5 mcg/kgmin appears optimal for restoring systolic and diastolic function post-resuscitation without adversely affecting myocardial oxygen consumption.</AbstractText> |
1,646 | Attenuated adult biphasic shocks compared with weight-based monophasic shocks in a swine model of prolonged pediatric ventricular fibrillation. | To compare the safety and efficacy of attenuated adult biphasic shocks with standard monophasic weight-based shocks in a piglet model of prolonged prehospital ventricular fibrillation (VF).</AbstractText>If attenuated adult shocks are safe and effective for prehospital pediatric VF, automated external defibrillators (AEDs) can be easily adapted for pediatric use.</AbstractText>After 7 min of untreated VF, piglets were randomized to treatment with attenuated adult biphasic shocks or weight-based monophasic shocks. The attenuated adult biphasic group received 200/300/360 J shocks, attenuated by specialized pediatric electrodes to 51/78/81 J and the monophasic weight-based control group received 2/4/4 J/kg shocks. Forty-eight female piglets were studied, 16 in each of three weight categories: 4 kg (neonatal), 14 kg (younger child) and 24 kg (older child). The primary outcome measures of efficacy and safety were 24h survival with good neurological outcome and post-resuscitation left ventricular ejection fraction (LVEF), respectively.</AbstractText>For the 24 kg piglets, attenuated adult biphasic shocks resulted in superior 24 h survival with good neurological outcome (6/8 versus 0/8, P < 0.001) and greater LVEF 4 h post-resuscitation (34 +/- 4% versus 18 +/- 5%, P < 0.05). For the 14 and 4 kg piglets, 24 h survival with good neurological outcome occurred in 7/8 versus 5/8 and 7/8 versus 3/8, respectively, and LVEF 4 h post-resuscitation was 30 +/- 3% versus 36 +/- 6% and 30 +/- 3% versus 22 +/- 4%, respectively.</AbstractText>The escalating attenuated adult biphasic dosage strategy was at least as safe and effective as the standard weight-based monophasic dose over a wide range of weights in this piglet model of prehospital VF. This work supports the concept of using an attenuated adult biphasic dosage in children.</AbstractText> |
1,647 | [Ablative strategy: a definite treatment for cardiac arrhythmias?]. | The development of radiofrequency catheter ablation has dramatically changed the therapeutic approach of cardiac arrhythmias. All atrial rhythm disturbances are now amenable to ablative strategy. Ablation has become the first-line therapy for atrial flutter. Atrial fibrillation, a major factor of morbidity and mortality, is now a target for this radical treatment. Ablation of pulmonary vein foci, eventually associated to atrial linear lesions, raises the possibility of suppressing atrial fibrillation. The success rate is now as high as 70 to 85%, depending on the form of atrial fibrillation. For atrioventricular reentrant tachycardia either nodal or over an accessory pathway, ablation is the reference treatment with success rates of 99%. All symptomatic Wolff-Parkinson-White syndromes can be definitely cured by this technique. At the ventricular level, the procedures are often more complexes, due to advanced cardiomyopathy. However, most of sustained ventricular tachycardias can be cured by ablation. The success rates are somewhat lower (about 80%). The challenge for the next years is ablation of premature ventricular beats initiating ventricular fibrillation. The technique is also improving from day-to-day (88% success rate) and makes rise the hope of curing sudden death. |
1,648 | [Atrial fibrillation].<Pagination><StartPage>258</StartPage><EndPage>265</EndPage><MedlinePgn>258-60, 262-5</MedlinePgn></Pagination><Abstract><AbstractText>Atrial fibrillation is a common arrhythmia which consequences include disabling symptoms, haemodynamic impairment and frightening embolic complications. In 3/4 cases, they are represented by cerebrovascular accidents responsible of death or disabling sequella. Underlying heart disease is present in 70% of AF patients. Endpoints of therapy include: 1. prevention of embolic complications using oral anticoagulation in patients at risk; 2. control of symptoms and prevention of haemodynamic impairment either by restoring and maintaining sinus rhythm or by controlling ventricular heart rate. The same principles should be applied for emergency treatment: aside from AF with haemodynamic compromise (hypotension or syncope) which requires urgent electrical cardioversion, AF termination may be obtained with intravenous or oral antiarrhythmic therapy or the treatment confined to slowing of heart rate. Selecting the appropriate antiarrhythmic therapy for prevention of recurrences is based on the type of AF, paroxysmal or persistent, symptoms, underlying heart disease and left ventricular function. For patients refractory to drug therapy, non pharmacologic treatment represents an option including pacemaker, double chamber defibrillator, and radiofrequency ablation of ectopic foci most often located in the pulmonary veins or pulmonary vein isolation or surgery particularly if there is an indication for open-chest surgery. Non-pharmacological therapies should be restricted to very symptomatic patients who failed pharmacological therapy.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Lévy</LastName><ForeName>Samuel</ForeName><Initials>S</Initials><AffiliationInfo><Affiliation>Service de cardiologie, CHU Hôpital Nord, 13915 Marseille Cedex 20. [email protected]</Affiliation></AffiliationInfo></Author></AuthorList><Language>fre</Language><PublicationTypeList><PublicationType UI="D004740">English Abstract</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList><VernacularTitle>Fibrillation atriale.</VernacularTitle></Article><MedlineJournalInfo><Country>France</Country><MedlineTA>Rev Prat</MedlineTA><NlmUniqueID>0404334</NlmUniqueID><ISSNLinking>0035-2640</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D001281" MajorTopicYN="Y">Atrial Fibrillation</DescriptorName><QualifierName UI="Q000145" MajorTopicYN="N">classification</QualifierName><QualifierName UI="Q000150" MajorTopicYN="N">complications</QualifierName><QualifierName UI="Q000628" MajorTopicYN="N">therapy</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004617" MajorTopicYN="N">Embolism</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D004638" MajorTopicYN="N">Emergency Treatment</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D006801" MajorTopicYN="N">Humans</DescriptorName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>2004</Year><Month>5</Month><Day>12</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2004</Year><Month>6</Month><Day>2</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2004</Year><Month>5</Month><Day>12</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">15134227</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">15133886</PMID><DateCompleted><Year>2004</Year><Month>05</Month><Day>20</Day></DateCompleted><DateRevised><Year>2016</Year><Month>03</Month><Day>23</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">1530-440X</ISSN><JournalIssue CitedMedium="Print"><Issue>92</Issue><PubDate><Year>2004</Year><Month>Mar</Month></PubDate></JournalIssue><Title>Evidence report/technology assessment (Summary)</Title><ISOAbbreviation>Evid Rep Technol Assess (Summ)</ISOAbbreviation></Journal>Effects of omega-3 fatty acids on arrhythmogenic mechanisms in animal and isolated organ/cell culture studies. | Atrial fibrillation is a common arrhythmia which consequences include disabling symptoms, haemodynamic impairment and frightening embolic complications. In 3/4 cases, they are represented by cerebrovascular accidents responsible of death or disabling sequella. Underlying heart disease is present in 70% of AF patients. Endpoints of therapy include: 1. prevention of embolic complications using oral anticoagulation in patients at risk; 2. control of symptoms and prevention of haemodynamic impairment either by restoring and maintaining sinus rhythm or by controlling ventricular heart rate. The same principles should be applied for emergency treatment: aside from AF with haemodynamic compromise (hypotension or syncope) which requires urgent electrical cardioversion, AF termination may be obtained with intravenous or oral antiarrhythmic therapy or the treatment confined to slowing of heart rate. Selecting the appropriate antiarrhythmic therapy for prevention of recurrences is based on the type of AF, paroxysmal or persistent, symptoms, underlying heart disease and left ventricular function. For patients refractory to drug therapy, non pharmacologic treatment represents an option including pacemaker, double chamber defibrillator, and radiofrequency ablation of ectopic foci most often located in the pulmonary veins or pulmonary vein isolation or surgery particularly if there is an indication for open-chest surgery. Non-pharmacological therapies should be restricted to very symptomatic patients who failed pharmacological therapy. |
1,649 | Implantable loop recorders: a novel method to judge patient perception of atrial fibrillation. Preliminary results from a pilot study. | At the present time, several techniques are used or are under investigation for atrial fibrillation (AF) therapy. Nowadays, no well-defined target for such therapies has been yet completely identified. Furthermore, AF is an arrhythmia with high rates of recurrences, both symptomatic and asymptotic. Thus the measure of therapy success rates not only based on symptom perception remains a goal to be reached.</AbstractText>This study investigates the role of an implantable loop recorder (ILR) as an additional tool to identify initiating and perpetuating mechanisms of AF. The role of right atrial linear ablation (RALA) procedures is also investigated using the monitoring capabilities of the ILR.</AbstractText>Nine patients (mean age 63.8 +/- 5.9) with paroxysmal AF were referred to our institution as candidates for AF ablation. All patients (pts) had in their medical history several years of AF episodes. Therefore pts were aware of AF related symptoms. Six of them were implanted with an ILR before ablation and were monitored one month before and six months after the procedure. The ILRs stored 54 patient activated events (PAE) and 124 automatically activated events (AAE). 68% of PAEs and 67% of AAEs were classified as appropriate. Most common reasons for inappropriate detections were premature atrial or ventricular contractions among PAEs and undersensing among AAEs. The arrhythmia onset was properly identified in 4 pts (44%). The average AF recurrence rate was 10.8 +/- 3.5 ep/month before ablation and 5.0 +/- 1.8 ep/month after the procedure ( p = 0.042).</AbstractText>The ILR may be a helpful tool in monitoring pts undergoing ablation. Dedicated AF detection characteristics could give additional value to the device. RALA appears as a feasible, safe and relatively effective first approach in AF therapy.</AbstractText> |
1,650 | Outcomes and in-hospital treatment of out-of-hospital cardiac arrest patients resuscitated from ventricular fibrillation by early defibrillation. | To describe and evaluate the in-hospital treatment of ventricular arrhythmias and underlying structural heart disease in patients who survive ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) in a region with a high survival rate after hospital discharge.</AbstractText>The study included all patients presenting in Olmsted County, Minnesota, who had experienced OHCA between November 1990 and December 2000 and who underwent defibrillation of VF by an emergency medical service system.</AbstractText>Of 200 patients who experienced VF arrest, 138 (69%) survived to hospital admission (7 died in the emergency department before admission), and 79 (40%) were discharged. Of patients who were discharged, 37 (47%) had a reversible cause of the arrest (perimyocardial infarction) and received treatment of the primary process. The other 42 patients who were discharged had ischemic coronary heart disease (CHD) (n=25), nonischemic CHD (n=10), or idiopathic VF (n=7). Four of the patients with CHD but no left ventricular dysfunction were treated with coronary artery bypass grafting or percutaneous coronary intervention alone. A total of 52 patients (66%) were candidates for electrophysiologic testing. Of these patients, 48 (92%) underwent electrophysiologic testing; of these patients, 10 received amiodarone alone, and 35 received an implantable cardioverter-defibrillator (ICD) (of whom 3 also received amiodarone). Patients who did not receive ICD therapy typically presented before 1998 with CHD and underwent coronary artery bypass grafting or percutaneous coronary intervention only. Of 79 patients who were discharged, 14 (18%) with an ICD have received subsequent shocks. Nineteen (24%) of 79 patients have died, 5 of a primary cardiac etiology (including 2 with repeated OHCA).</AbstractText>The VF OHCA survival rate is high in the setting of rapid defibrillation, with 40% of patients being discharged from the hospital. By the end of the 10-year study, more patients were receiving antiarrhythmic therapy, in particular ICD implantation, after hospital admission. Overall, the long-term survival in patients with VF OHCA is favorable.</AbstractText> |
1,651 | Bundle branch block on alternate beats during atrial fibrillation. | This article reports a case of tachycardia-dependent right bundle branch block (RBBB) occurring during atrial fibrillation. In some sections of the recording, an alternans occurs between complexes with a complete RBBB pattern and complexes showing normal intraventricular conduction or incomplete RBBB. Alternans is frequently observed during phases of fast and nearly regular rhythm, but it occurs even in the presence of a markedly irregular ventricular response. The RBBB alternans associated with short and regular RR intervals is likely to represent a manifestation of 2:1 bundle branch supernormal conduction, whereas alternans occurring with irregular cycles expresses a complex interaction between the RR cycle length and some mechanisms affecting intraventricular conduction, such as tachycardia-dependent bundle branch block, supernormal conduction and concealed retrograde activation of the anterogradely blocked bundle branch (the so-called "linking" phenomenon). |
1,652 | Predictors of in-hospital ventricular fibrillation or torsades de pointes in patients with acute symptomatic bradycardia. | Severe bradyarrythmias remain as an important cause for hospital urgent admission and these patients can suffer potentially lethal complications (such as ventricular fibrillation [VF] and torsades de pointes [TdP]) between hospital admission and final therapy. Incidence and predictors of these tachyarrhythmias have not been well established. We retrospectively studied all consecutive patients (N = 243, age 75 +/- 10 years; 47% men) admitted to the emergency department of a general hospital between January 1998 and July 2000 for symptomatic bradyarrhythmia. Concomitant therapy included diuretics (25%), digitalis (10%), beta-blockers (10%), amiodarone (2%), and verapamil or diltiazem (8%). Syncope was the most frequent symptom at admission (54%). The most prevalent inclusion bradyarrhythmia was > or =second-degree AV block (82%). Eleven patients (4.5%) presented VF or TdP. Univariate predictors for these complications were previous amiodarone or diuretic intake, presentation as syncope, low serum potassium level, and longer QTc at admission. Multivariate analysis with logistic regression showed only therapy with diuretics and/or amiodarone and QTc at admission as significant predictors for TdP or VF development. Incidence of VF or TdP in patients admitted for symptomatic bradyarrhythmia is relatively important. A prolonged QTc interval and/or therapy with amiodarone or diuretics can predict their presentation. |
1,653 | Idiopathic Brugada-type electrocardiographic pattern in an octogenarian. | The prognosis of idiopathic Brugada-type ECG pattern in asymptomatic people is unknown. We report a case of an 85-year-old man who had persistent Brugada-type ECG pattern without associated clinical symptoms. This illustrates that the persistent Brugada-type ECG can be present with normal longevity. |
1,654 | Brugada syndrome with atypical ECG: downsloping ST-segment elevation in inferior leads. | We present an unusual case of a young Thai immigrant, symptomatic, who had suffered prior episodes of syncope with strong family background: male, first-degree relatives, younger than 45 years old who had died suddenly. The rest ECG, with the patient asymptomatic at the time, showed persistent ST-segment elevation, in inferior leads and "mirror" image in the anterior wall, which were not modified with sublingual nitrates, in absence of demonstrable structural heart disease by chest X-rays and echocardiogram, hypothermia, ischemia, or electrolytic disorders. Holter monitoring revealed at dawn, a short episode of polymorphic ventricular tachycardia of short onset extrasystole coupling, which evolved into asystole and sudden cardiac death. We believe this is a sudden unexplained death syndrome, although we did not have a chance to conduct a genetic study. |
1,655 | Spectral and correlation analyses of the verapamil-induced conversion of ventricular fibrillation to tachycardia in isolated rat hearts. | Ventricular tachycardia (VT) is considered to be the most common precursor of ventricular fibrillation (VF). However, the mechanisms underlying the transition from VT to VF remain unclear. Here, we investigated whether and how perfusion of the heart with verapamil, a blocker of L-type calcium channels, changed the macro-dynamics of the heart between VT and VF. The experiments were performed with Langendorff perfused isolated rat hearts, in which left ventricular pressure and left ventricular cardiomyogram were measured. Sustained VT or VF was induced by burst pacing of the left ventricular muscles. During sustained VF, verapamil perfusion resulted in the conversion of VF to VT. A cross-correlation analysis between left ventricular cardiomyogram and left ventricular pressure revealed that the correlation coefficient was small during VF, but became larger during VT. This study showed that inactivation of L-type Ca(2+) channels occurred during verapamil-induced conversion of pacing-induced sustained VF to VT, and characterized the changes in macro-dynamics of the heart associated with the transition. |
1,656 | Shock coil failure secondary to external irradiation in a patient with implantable cardioverter defibrillator. | The use of implantable cardioverter defibrillator (ICD) in the management of malignant ventricular arrhythmia is well established. Radiation treatment is common in malignant neoplasms, but the direct effect of irradiation in ICD is largely not well understood. We describe a case where radiation treatment probably led to shock coil failure. |
1,657 | Hyperkalemia induced T wave oversensing leading to loss of biventricular pacing and inappropriate ICD shocks. | Inappropriate ICD shocks remain a common problem. Double counting of single ventricular events can occur with biventricular ICDs implanted before univentricular sensing was available. Often this is due to a tachyarrhythmia or loss of left ventricular capture. This report describes a patient who developed hyperkalemia during hemodialysis, received inappropriate ICD shocks and experienced loss of biventricular pacing due to T wave rather than QRS double counting. Oversensing was abolished by reducing the potassium content of the dialysis bath. This underscores the need for careful interpretation of saved electrograms to determine the cause for, and appropriate treatment of, device related problems. |
1,658 | Inappropriate therapy from a defibrillator complicating transcoronary ablation of septal hypertrophy in a patient with hypertrophic obstructive cardiomyopathy. | This case report describes a patient with obstructive hypertrophic cardiomyopathy who received therapy inappropriately from his implanted defibrillator, subsequent to transcoronary alcohol ablation for septal hypertrophy (TASH). Widening of the intracardiac electrogram postablation resulted in "double counting" of the intrinsic ventricular electrogram by the device and inappropriate tachycardia detection. |
1,659 | Ventricular fibrillation without overt cardiomyopathy as first presentation of organic cation transporter 2-deficiency in adolescence. | This case report describes ventricular fibrillation without overt cardiomyopathy as the presenting symptom of primary carnitine deficiency due to organic cation transporter 2 (OCTN2)-deficiency in a 15-year-old girl. Normally this disease presents early in life with hypoketotic hypoglycemia, muscle weakness, and/or cardiomyopathy. The patient fully recovered after carnitine supplementation. Recognition of this disease is important because its treatment is easy and effective. |
1,660 | Insertable loop recorder use for detection of intermittent arrhythmias. | The advent of prolonged monitoring with the implanted loop recorders has revolutionized the quest for detection of elusive infrequent arrhythmias in patients with unexplained syncope. The capability of prolonged monitoring has permitted us to obtain symptom rhythm correlation in the majority of patients suspected to have underlying infrequent arrhythmia. The implanted loop recorder is easily implanted in the left pectoral region with a minimally invasive procedure, providing at least 14 months of continuous monitoring that is both patient and automatically activated. Several recent studies suggest that it plays a major role in patients with infrequent symptoms and suspected arrhythmia, including patients with syncope and conduction disturbances, mild to moderate underlying heart disease, and atypical epilepsy. In a randomized trial, the device was found to be cost-effective and improved diagnostic yield compared to conventional tilt and electrophysiological testing. Wider application of prolonged monitoring is ongoing, including assessment of ventricular arrhythmias, atrial fibrillation, and conduction disturbances. The implantable loop recorder is most useful in patients with infrequent unexplained syncope when noninvasive testing is negative. |
1,661 | [Arrhythmic activity of the papillary muscle induced by high frequency stimulation: n1 rhythms,transition forms and hysteresis]. | Cardiac tissues are able to work within a wide range of frequencies to respond to the changing requirements an organism may have. However, during these frequency variations and under certain pathologic conditions arrhythmias such as blocks, tachycardia, fibrillation, etc, may arise some with fatal consequences. For this reason several experimental procedures have been developed that have shown to be useful in studying whole heart properties, or as an alternative from portions of it when changes in its work rate are imposed. This study reports different phenomena occurring in the papillary muscle of the guinea pig heart when stimulated at very high frequency, of several tens of pps, while analyzing its responses during gradual increments starting at 1 (pulses per second). We found that in our conditions papillary muscles display N:1 rhythms with progressive higher N; further more we found that between one and the next rhythm diverse transition patterns appear, among them a new one that we have named "burst pattern". Finally we show that our system exhibits a generalized process of hysteresis by frequency, being this the first report for guinea pig cardiac tissue and the first one to show also the presence of several hysteresis loops in the same experiment. Due to the large volume of generated data we used a faster and easier way to analyze and display them, based on the fast Fourier transform (FFT). The method is briefly described. |
1,662 | Functional characterization of a trafficking-defective HCN4 mutation, D553N, associated with cardiac arrhythmia. | Hyperpolarization-activated cyclic nucleotide-gated channel 4 gene HCN4 is a pacemaker channel that plays a key role in automaticity of sinus node in the heart, and an HCN4 mutation was reported in a patient with sinus node dysfunction. Expression of HCN4 in the heart is, however, not confined to the sinus node cells but is found in other tissues, including cells of the conduction system. On the other hand, mutations in another cardiac ion channel gene, SCN5A, also cause sinus node dysfunction as well as other cardiac arrhythmias, including long QT syndrome, Brugada syndrome, idiopathic ventricular fibrillation, and progressive cardiac conduction disturbance. These observations imply that HCN4 abnormalities may be involved in the pathogenesis of various arrhythmias, similar to the SCN5A mutations. In this study, we analyzed patients suffering from sinus node dysfunction, progressive cardiac conduction disease, and idiopathic ventricular fibrillation for mutations in HCN4. A missense mutation, D553N, was found in a patient with sinus node dysfunction who showed recurrent syncope, QT prolongation in electrocardiogram, and polymorphic ventricular tachycardia, torsade de pointes. In vitro functional study of the D553N mutation showed a reduced membranous expression associated with decreased If currents because of a trafficking defect of the HCN4 channel in a dominant-negative manner. These data suggest that the loss of function of HCN4 is associated with sinus nodal dysfunction and that a consequence of pacemaker channel abnormality might underlie clinical features of QT prolongation and polymorphic ventricular tachycardia developed under certain conditions. |
1,663 | Short-acting beta-adrenergic antagonist esmolol given at reperfusion improves survival after prolonged ventricular fibrillation. | High catecholamine concentrations are cytotoxic to cardiac myocytes. We hypothesized that myocardial interstitial catecholamine levels are greatly elevated immediately after long-duration ventricular fibrillation (VF), defibrillation, and reperfusion and that the short-acting beta-antagonist esmolol administered at reperfusion would protect against this catecholamine surge and improve survival.</AbstractText>In part 1 of this study, catecholamines from myocardial interstitial fluid (ISF) and aortic and coronary sinus plasma were quantified by use of 3H-labeled radioenzymatic assay in 8 open-chest, anesthetized pigs. Eight minutes of electrically induced VF was followed by internal defibrillation and reperfusion. By 4 minutes of VF, ISF norepinephrine increased significantly, from 1.3+/-0.3 to 7.4+/-2.4 ng/mL. Epinephrine increased significantly, from 0.4+/-0.2 to 1.5+/-0.7 ng/mL. ISF norepinephrine and epinephrine peaked at 219.2+/-92.1 and 63.7+/-25.1 ng/mL after defibrillation and reperfusion and decreased significantly to 12.2+/-3.5 and 6.7+/-3.1 ng/mL 23 minutes after defibrillation. Transcardiac catecholamine changes were similar. In part 2, 8 minutes of VF was followed by external defibrillation in anesthetized, closed-chest pigs. Animals received 1.0 mg/kg esmolol (n=8) or saline (n=8) intravenously at the start of cardiopulmonary resuscitation (CPR). Advanced cardiac life support, including CPR and epinephrine, was delivered to both groups. Esmolol before reperfusion improved return of spontaneous circulation and 4-hour survival (7/8 versus 3/8 survivors, chi2 P<0.05).</AbstractText>Transcardiac and ISF norepinephrine and epinephrine levels are briefly massively elevated after 8 minutes of VF, defibrillation, and reperfusion. A short-acting beta-antagonist administered immediately after defibrillation improves return of spontaneous circulation and 4-hour survival after this prolonged VF.</AbstractText> |
1,664 | Bretylium, an organic quaternary amine, inhibits the Na,K-ATPase by binding to the extracellular K-site. | The quaternary amine, bretylium, is a class III antiarrhythmic drug used to treat ventricular tachycardia and fibrillation. The primary mode of action for bretylium is thought to be inhibition of voltage-gated K(+) channels. While the Na,K-ATPase has been the pharmacological target of cardiac glycosides for over a century, recent evidence has shown that bretylium may also inhibit the Na pump. Our experimental findings support and extend these previous reports and provide definitive evidence supporting the previous suggestion that bretylium and K compete for the Na pump. We find that bretylium inhibits the Na pump in a dose-dependent manner in both Na,K-ATPase (IC(50) 4.5 mM) and Rb flux experiments (IC(50) 3.5 mM). Furthermore, we show that bretylium and Rb(+) competes for an extracellular site by measuring ouabain-sensitive (86)Rb flux in intact human red blood cells; that is, there is an apparent increase in K(m) for Rb(+) in the presence of 5 mM bretylium, while V(max) remains unchanged. We also determined that unlike K(+), bretylium does not facilitate the hydrolysis of E2-P. However, it stabilizes this conformation by reducing the ability of K(+) to facilitate dephosphorylation. Finally, we show that bretylium, like K(+), reduces [(3)H]ouabain binding to the Na pump. Taken together, these data are consistent with bretylium binding to the extracellular facing cation site within the E2-P state of the enzyme. Moreover, these findings suggest that bretylium may serve as an effective tool for freezing the pump in an extracellularly cation-bound phosphorylated intermediate, which will aid in future structural analyses. |
1,665 | Heart rate regularisation in patients with permanent atrial fibrillation implanted with a VVI(R) pacemaker. | Irregularity of ventricular cycles is a cause of haemodynamic impairment and symptoms in patients with atrial fibrillation (AF).</AbstractText>Aim of the study was to determine the optimal pacing rate to stabilise ventricular cycle length at rest in patients with chronic AF, bradycardiac symptoms and VVI pacing.</AbstractText>The compensatory pause (CP) in AF, as defined by Langendorf, was used as a reference value in pacing the heart. The spontaneous mean heart rate (MHR) was assessed with the PM OFF. The CP was then calculated with the pacing rate programmed at 40 bpm. Four pacing rates were tested: rate of the CP (RCP), RCP + 5 bpm, RCP - 5 bpm and RCP - 10 bpm.</AbstractText>RCP provided a good estimate of the MHR (r = 0.92). Pacing percentage (P%) was 24 +/- 15% at the pacing rate of RCP - 10 bpm, 39 +/- 19% at RCP - 5 bpm, 63 +/- 17% at RCP, and 79 +/- 19% at RCP + 5 bpm (p < 0.001). The corresponding HR modestly increased from 65 +/- 13 bpm to 66 +/- 13 bpm (p = NS), 68 +/- 13 bpm (p < 0.001) and 71 +/- 13 bpm (p < 0.001), respectively.</AbstractText>The RCP estimates, during pacing, what the spontaneous MHR would be. Ventricular stimulation at the RCP causes a high P%, stabilising cardiac cycles with a modest increase in HR.</AbstractText>Copyright 2004 The European Society of Cardiology</CopyrightInformation> |
1,666 | Superior vena cava syndrome and syncope in an implantable cardioverter defibrillator recipient. | We describe the case of a recipient of an implantable cardioverter defibrillator with multiple syncopal episodes due both to superior vena cava obstruction and electrical instability. These complications occurred in the presence of two transvenous implantable cardioverter defibrillator leads. The patient has been managed conservatively with anticoagulants and new antiarrhythmic drugs with improvement in both his clinical problems. |
1,667 | Primary hyperparathyroidism and arrhythmic storm in a patient with an implantable cardioverter defibrillator for primary prevention of sudden death. | A case of a patient with an automatic cardioverter defibrillator (ICD) and recurrent ventricular arrhythmic storms related to primary hyperparathyroidism and hypercalcaemia is reported: medical therapy was ineffective and only surgical resection of the parathyroid adenoma resolved this complex clinical condition. |
1,668 | ICD-implantation guidelines versus clinical practice: a prospective study of out-of-hospital cardiac arrest survivors. | The aim of this study was prospectively to compare clinical practice of implantable cardioverter defibrillator (ICD) use with current guidelines in out-of-hospital cardiac arrest (OHCA) survivors.</AbstractText>From January 2000 till March 2002, 70 consecutive patients (pts) discharged from 15 hospitals after OHCA, with ventricular fibrillation (VF) as initial rhythm were included. Documentation of diagnosis, left ventricular function, ischaemia, electrophysiological studies (EPS), and decisions regarding ICD implantation were obtained from medical records. An expert committee compared these data with current guidelines. According to these guidelines 18 pts (26%) had an ICD indication and received an ICD while 37 pts (53%) had no indication and did not receive an ICD. In 13 pts without acute myocardial infarction insufficient diagnostic procedures were performed to permit a decision on ICD indication, hence no ICD was implanted. Two pts had an ICD indication but did not receive an ICD. During the follow-up with duration of 25 months (range 12-38 months), two sudden deaths occurred in the group of pts without an ICD. Of the pts with an ICD, 4 pts (22%) were reported to have received one or more shocks for VT/VF.</AbstractText>In at least 21% of OHCA survivors, insufficient diagnostic procedures concerning the indication for ICD implantation were performed or no ICD was implanted when indicated, despite clear guidelines. In particular, there was no proof of ischaemia prior to revascularization and no confirmation of the absence of ischaemia and EPS thereafter. Clinicians should be guided better in evaluating pts after OHCA concerning the indication for ICD implantation, especially when a transient of reversible condition was present or when treatment was sufficiently established safely to refrain from ICD implantation.</AbstractText>Copyright 2004 The European Society of Cardiology</CopyrightInformation> |
1,669 | Mode of initiation and ablation of ventricular fibrillation storms in patients with ischemic cardiomyopathy. | We report on the initiation of ventricular fibrillation (VF) storm in patients with ischemic cardiomyopathy (ICM) and the results of targeted ablation to treat VF storm.</AbstractText>Monomorphic premature ventricular contractions (PVCs) have been shown to initiate VF in patients without structural heart disease.</AbstractText>A total of 29 patients with ICM and documented VF initiation were identified. In 21 patients, VF storm was controlled with antiarrhythmic drugs and/or treatment of heart failure. Eight patients with VF (mean 52 +/- 25 episodes) refractory to medical management required ablation. All patients underwent three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, California), and PVCs were mapped when present. Scarred areas were identified using voltage mapping.</AbstractText>Monomorphic PVCs initiated VF in all 29 identified patients. Five of eight patients requiring ablation had frequent PVCs that allowed PVC mapping. The earliest activation site was consistently located in the scar border zone. The PVCs were always preceded by a Purkinje-like potential (PLP). Ablation was successfully performed at these sites. In three patients, infrequent PVCs prevented mapping, but PLPs were recorded around the scar border. Ablation targeting these potentials along the scar border was successfully performed. During follow-up (10 +/- 6 months), one patient had a single VF episode and another developed sustained, monomorphic ventricular tachycardia. There was no recurrence of VF storm.</AbstractText>Ventricular fibrillation in ICM is triggered by monomorphic PVCs originating from the scar border zone with preceding PLPs; targeting these PVCs may prevent VF recurrence. In the absence of PVCs, both substrate mapping and ablation appear to be equally effective.</AbstractText> |
1,670 | Predictors of new malignant ventricular arrhythmias after coronary surgery: a case-control study. | We sought to investigate the relationship between perioperative factors and the occurrence of ventricular tachycardia (VT) and ventricular fibrillation (VF), as well as the impact of VT/VF on early and late mortality.</AbstractText>Both VT and VF are rare but serious complications after coronary artery bypass graft surgery (CABG), and their etiology and implications remain uncertain.</AbstractText>Data on 4,411 consecutive patients undergoing CABG (1,154 [25.8%] had off-pump surgery) between April 1996 and September 2001 were extracted from a prospective database and analyzed. Odds ratios (ORs) describing associations between possible risk factors and VT/VF were estimated separately. Factors observed to be significantly associated with VT/VF were further investigated using multivariate logistic regression.</AbstractText>Sixty-nine patients suffered VT/VF (1.6%). There were 61 (1.4%) in-hospital/30-day deaths, 15 among patients who had postoperative VT/VF (21.7%). Patient factors independently associated with an increase in the odds of VT/VF included age <65 years, female gender, body mass index <25 kg/m(2), unstable angina, moderate or poor ejection fraction, and the need for inotropes and an intra-aortic balloon pump (OR 1.72 to 4.47, p < 0.05). After adjustment, off-pump surgery was associated with a substantial but nonsignificant protective effect against VT/VF (OR 0.53, 95% confidence interval [CI] 0.25 to 1.13; p = 0.10). Actuarial survival at two years was 98.2% among patients who had VT/VF and who survived to discharge/30 days, compared with 97.0% for the control group (adjusted hazard ratio 0.96 (95% CI 0.40 to 2.31, p = 0.92).</AbstractText>The incidence of VT/VF is low in patients undergoing coronary surgery but is associated with high in-hospital mortality. The late survival of the discharged VT/VF patients compares favorably with that of controls.</AbstractText> |
1,671 | Predictors of stroke in patients paced for sick sinus syndrome. | This study was an analysis of factors associated with stroke in a population of patients paced for sinus node dysfunction in a large prospective clinical trial (Mode Selection Trial [MOST]).</AbstractText>The effects of dual-chamber versus single-chamber ventricular pacing on subsequent stroke in patients with sinus node dysfunction are not known.</AbstractText>A total of 2,010 patients with sinus node dysfunction were randomized to ventricular or dual-chamber pacing and followed for a median of 33.1 months.</AbstractText>The median participant age was 74 years. During 5,664 patient-years of follow-up, 90 strokes (11 hemorrhagic) occurred. By life-table analysis, the rate of stroke was 2.2% (95% confidence interval [CI] 1.6 to 2.9) at one year and 5.8% (95% CI 4.5 to 7.1) at four years. The incidence of stroke was not significantly different in dual-chamber (4%) as compared with ventricular-paced patients (4.9%) (hazard ratio [HR] 0.82, 95% CI 0.54 to 1.25, p = 0.36). Multivariable analysis demonstrated that significant predictors of stroke included prior stroke or transient ischemic attack, Caucasian race, hypertension, prior systemic embolism, and New York Heart Association functional class III or IV (p < 0.05); pacing mode remained non-significant after adjustment for these factors (p = 0.37). Clinically reported atrial fibrillation after implantation was a risk factor for stroke in this cohort after adjustment for other predictors of stroke (p = 0.042, HR 1.68 [95% CI 1.02 to 2.76]).</AbstractText>Clinical characteristics, but not mode of pacing, were associated with subsequent stroke in patients paced for sinus node dysfunction.</AbstractText> |
1,672 | [Therapeutic effects of left ventricular assist device on pump failure caused by acute myocardial infarction]. | To evaluate the therapeutic effects of a left ventricular assist device (LVAD) on pump failure caused by acute myocardial infarction (AMI) in dogs.</AbstractText>The pump failure caused by AMI was established in 18 dogs, 9 of them were treated with a LVAD that could expel the autoblood from the left ventricle into the aorta and named the experimental group, and the rest of them were treated with intravenous infusion and served as the control group. The changes of arrhythmia, mortality, pulmonary capillary wedge pressure (PCWP), left ventricular end-diastolic pressure (LVEDP), peripheral artery pressure and the diameter of left ventricular chamber were observed.</AbstractText>The ratio of ventricular extrasystole and the mortality resulted from ventricular fibrillation of the experimental group were lower than that of the control group. The systolic blood pressure of peripheral artery of the control group was significantly lower (< 100 mmHg) than that of the experimental group (>100 mmHg, P < 0.01). The PCWP and LVEDP of the experimental group during all the stages 45 minutes after the procedures were significantly lower than that of the control group (P < 0.01). The left ventricular end-diastolic diameter of the control group was larger than that of the experimental groups (P < 0.01).</AbstractText>To assist circulation by expelling autoblood from left ventricle into aorta in dogs with AMI could reduce the frequency of ventricular fibrillation, improve hemodynamics, and prevent the enlargement of left ventricle. Therefore, it could play an important role in assisting the left ventricular functions.</AbstractText> |
1,673 | Sinus node function in patients with Brugada-type ECG. | Some studies have shown that patients with Brugada syndrome (BS) have atrioventricular conduction disturbance, but their sinus node function has not been evaluated.</AbstractText>The patients group consisted of 59 male patients and 1 female patient with BS. Supraventricular and ventricular programmed electrical stimulation (PES) was performed. Ventricular fibrillation (VF) or sustained polymorphic ventricular tachycardia was induced by ventricular PES in 26 patients with BS (VF group), but was not induced in the other 34 patients (non-VF group). Sinus node function and conduction of the atrioventricular (AV) node in the control group, non-VF group and VF group were evaluated. Sinus node function was attenuated and the His - ventricle interval was prolonged in the VF group (corrected sinus node recovery time: 452+/-126 ms (VF group), 324+/-146 ms (non-VF group), Sino-atrial conduction time: 179+/-60 ms (VF group), 127+/-60 ms (non-VF group), His-ventricle interval: 41+/-9 ms (VF group), 35+/-8 ms (non-VF group)).</AbstractText>The function of both the sinus node and AV node are attenuated in patients with PES-induced VF.</AbstractText> |
1,674 | Minimally-diluted blood cardioplegia supplemented with potassium and magnesium for combination of 'initial, continuous and intermittent bolus' administration. | The present study was designed to examine the hypothesis that minimally-diluted blood cardioplegia (BCP) supplemented with potassium and magnesium provides superior myocardial protection in comparison with the standard-diluted BCP for a combination of 'initial, continuous, and intermittent bolus' BCP administration.</AbstractText>Seventy patients undergoing elective coronary revascularization between 1997 and 2001 (M : F =55:15, mean age 67.6+/-7.5 years) were randomly divided into 2 groups: Group C (n=35) was given the standard 4:1-diluted blood-crystalloid BCP, and Group M (n=35) was given minimally-diluted BCP supplemented with potassium-chloride and magnesium-sulfate. The BCP temperature was maintained at 30 degrees C. Cardioplegic arrest was induced with 2 min of initial antegrade BCP infusion, followed by continuous retrograde BCP infusion. Intermittent antegrade BCP was infused every 30 min for 2 min. The time required for achieving cardioplegic arrest was significantly shorter in Group M (47.5+/-16.3 vs 62.5+/-17.6 s, p<0.0001). The number of patients showing spontaneous heart beat recovery after reperfusion was significantly larger in Group M (28 vs 15, p=0.0029), and the number of patients suffering from atrial fibrillation during the postoperative period was significantly smaller in Group M (n=3 vs 11, p=0.034). Both the postoperative maximum dopamine dose (3.57+/-2.46 vs 5.44+/-2.23 microg/kg per min, p=0.0014) and peak creatine kinase-MB (19.5+/-8.5 vs 25.8+/-11.9 IU/L, p=0.0128) were significantly less in Group M. The number of patients showing paradoxical movement of the ventricular septum in the early postoperative echocardiography was significantly smaller in Group M (9 vs 24, p=0.0007).</AbstractText>These results suggest that 'initial, continuous and intermittent bolus' administration of minimally-diluted BCP supplemented with potassium and magnesium is a reliable and effective technique for intraoperative myocardial protection.</AbstractText> |
1,675 | Nicorandil protects against lethal ischemic ventricular arrhythmias and up-regulates endothelial nitric oxide synthase expression and sulfonylurea receptor 2 mRNA in conscious rats with acute myocardial infarction. | Nicorandil is an adenosine triphosphate sensitive K (K-ATP) channel opener and a nitric oxide donor. K-ATP channels and nitric oxide are important factors in ischemic preconditioning, which in turn suppresses reperfusion arrhythmias. The present study sought to evaluate whether nicorandil suppresses ischemic-induced ventricular arrhythmias and enhances sulfonylurea receptors (SUR 2; subunit of K-ATP channel), endothelial nitric oxide (eNOS), and inducible nitric oxide (iNOS) expression in the left ventricle after myocardial infarction without reperfusion. Thirty male Sprague-Dawley rats at 7 weeks of age were separated into three groups, as follows. Acute myocardial infarction was induced in twenty rats by ligating the left main coronary artery. Ten of these twenty rats were continuously administered nicorandil at 3 mg/kg/day i.p. The other ten rats were left untreated. The ten controls were untreated and sham-operated. After coronary ligation, ventricular arrhythmias were evaluated from stored ECG signals. At 24 hours after treatment, eNOS, iNOS, and SUR2 mRNA levels and eNOS, iNOS expression in the left ventricle were determined by reverse transcription polymerase chain reaction (RT-PCR) and by immunohistochemical staining, respectively. Nicorandil suppressed the total number of ventricular arrhythmias from 1 to 2 hours, the total duration of ventricular tachycardia from 2 to 3 hours, and that of ventricular fibrillation from 1 to 2 and from 4 to 5 hours after coronary ligation. Nicorandil improved the survival rate 24 hours after coronary ligation. Levels of SUR2 mRNA increased only in left ventricles treated with nicorandil, particularly in the non-ischemic myocardium. eNOS mRNA was enhanced 2.2-fold in the area at risk in infarcted controls compared to sham-operated rats. In the non-ischemic area and area at risk of rats treated with nicorandil compared to sham-operated rats, eNOS mRNA was enhanced 3.3- and 2.7-fold, respectively. Staining indicated that the highest concentrations of eNOS occurred in the endothelium and myocardium of the non-ischemic area of rats treated with nicorandil. iNOS mRNA was present in both the area at risk and the non-ischemic area only in infarcted rats, and levels thereof were higher in the area at risk than in the non-ischemic area. However, there was no difference in iNOS mRNA levels between nicorandil-treated rats and controls. iNOS exhibited stronger staining in the area at risk than in the non-ischemic area of both nicorandil-treated and infarcted controls, with no differences between these two groups of rats. The mechanisms of protection against lethal ventricular tachyarrhythmia in nicorandil may increase nitric oxide release by upregulated eNOS expression through the opening of K-ATP channels and/or a K-ATP channels opener itself after acute myocardial infarction. |
1,676 | [Remodeling in cardiac failure of functional class I due to arterial hypertension associated with ischemic heart disease]. | Hemodynamics and ventricular remodeling were studied echocardiographically in 192 men with heart failure (NYHA functional class I), arterial hypertension (AH) of stage I-III and clinical picture of ischemic heart disease (IHD). The latter presented in the patients with stable angina pectoris of FC I-II (SAP), unstable angina pectoris (UAP) without foci, paroxysmal atrial fibrillation, acute myocardial infarction (MI), postinfarction cardiosclerosis (PC) with SAP or UAP. The control group consisted of 41 healthy men. The patients had AH stage 1. The patients and healthy controls differed significantly by the size of the aorta, left atrium, thickness of the interventricular septum and posterior wall of the left ventricle. There was a significant left-ventucular hypertrophy in the groups with patients with MI, SAP and PC, UAP and PC (p < 0.001). In these groups the type of left ventricular remodeling was characterized as excentric type of left ventricular hypertrophy without its delatation. Normal left ventricular geometry was in healthy men, SAP, UAP, paroxysmal actual fibrillation. |
1,677 | A rapid method to quantify left atrial contractile function: Doppler tissue imaging of the mitral annulus during atrial systole. | Assess the value of peak atrial systolic mitral annular velocity (Aann) measured by Doppler tissue echocardiography to quantify left atrial systolic function.</AbstractText>We studied a total of 61 adults; 10 subjects without history of heart disease and 51 patients with a history of atrial fibrillation or undergoing evaluation for left ventricular systolic or diastolic dysfunction. Aann was obtained by averaging peak atrial systolic mitral annular velocities from the septal, lateral, anterior, and inferior annulus. Left atrial fractional area change (FAC) and fractional volume change (FVC) during atrial systole were calculated. The correlation between peak atrial systolic mitral annular velocity (Aann) and left atrial systolic FAC and FVC was determined.</AbstractText>Mean FAC and FVC were 27 +/- 12 and 40 +/- 14%, respectively; mean Aann was 11.2 +/- 3.2 cm/s. Linear regression analysis showed correlation between Aann and FAC (r = 0.71; p<0.001) and between Aann and FVC (r = 0.74; p<0.001).</AbstractText>Peak systolic mitral annular velocity correlates well with left atrial systolic FAC and FVC, thus providing an easy means to assess left atrial systolic function.</AbstractText> |
1,678 | Fatal complications after use of the Symmetry Aortic Connector in coronary artery bypass surgery. | During the last 2 years, 103 aortic saphenous vein graft anastomoses were performed in 68 patients undergoing off-pump coronary artery bypass by using the Symmetry Bypass System Aortic Connector. Of these patients, 2 died during the early postoperative period. In the first patient, after an episode of ventricular fibrillation and closed-chest cardiac massage, the sternum was opened and hemopericardium secondary to leakage of the proximal anastomotic device was found. The second patient died of ascending aortic dissection, the tear of which was likely to have originated from the proximal anastomotic site. |
1,679 | Does preoperative atrial fibrillation reduce survival after coronary artery bypass grafting? | Preoperative atrial fibrillation has been identified as a risk factor for reduced long-term survival after coronary artery bypass grafting. This study sought to determine whether atrial fibrillation is merely a marker for high-risk patients or an independent risk factor for time-related mortality.</AbstractText>From 1972 to 2000, 46,984 patients underwent primary isolated coronary artery bypass grafting; 451 (0.96% prevalence) had electrocardiogram-documented preoperative atrial fibrillation (n = 411) or flutter (n = 40). Characteristics of patients with and without atrial fibrillation were contrasted by multivariable logistic regression to form a propensity score. With this, comparable groups with and without atrial fibrillation were formed by pairwise propensity-matching to assess survival.</AbstractText>Patients with preoperative atrial fibrillation were older (67 +/- 9.0 versus 59 +/- 9.8 years, p < 0.0001), had more left ventricular dysfunction (66% versus 52%, p < 0.0001) and hypertension (73% versus 59%, p < 0.0001), but less severe angina (39% moderate or severe versus 49%, p < 0.0001). Many of these factors are themselves predictors of increased time-related mortality. In propensity-matched patients, survival at 30 days and at 5 and 10 years for patients with versus without atrial fibrillation was 97% versus 99%, 68% versus 85%, and 42% versus 66%, respectively, a survival difference at 10 years of 24%. Median survival in patients with atrial fibrillation was 8.7 years versus 14 years for those without it.</AbstractText>Atrial fibrillation in patients undergoing coronary artery bypass grafting is a marker for high-risk patients; in addition, atrial fibrillation itself substantially reduces long-term survival. Thus, if patients in atrial fibrillation require surgical revascularization, it is appropriate to consider performing a concomitant surgical ablation procedure.</AbstractText> |
1,680 | Early recurrence of arrhythmia in patients taking amiodarone or class 1C agents for treatment of atrial fibrillation or atrial flutter. | Amiodarone use for the prevention of recurrent atrial fibrillation or atrial flutter requires drug loading over a period of several days to weeks, whereas class 1C agents do not. Three hundred thirty-nine patients were evaluated during drug loading with amiodarone or class 1C agents, and it was found that recurrent arrhythmia was common, usually not persistent, and frequently asymptomatic. Recurrent arrhythmia was not more common with amiodarone. |
1,681 | Assessment of in-hospital cardiopulmonary resuscitation using Utstein template in a university hospital. | The aim of this study was to evaluate the effectiveness of in-hospital cardiopulmonary resuscitation (CPR) strategies and identify key predictors of post-CPR survival in a university hospital setting. Using a form recommended by the European Resuscitation Council, data regarding in-hospital CPR attempts from January 2001 to December 2002 were recorded and analyzed. The main outcomes of interest were immediate survival after CPR and survival to hospital discharge. Of 307 patients who suffered cardiac arrest in the study period, 103 (33.5%) were resuscitated. Of these 103 patients, 28 (27.2%) survived immediately and 12 (11.7%) survived to hospital discharge. The key predictors of immediate survival were CPR duration and initial cardiac rhythm as monitored by ventricular fibrillation/pulseless ventricular tachycardia (VF/VT). The key predictors of survival to hospital discharge were CPR duration, immediate defibrillation, Glasgow Coma Scale score, and Early Prediction Score. Together, our results suggest that in-hospital CPR strategies require improvement. They also underscore the importance of data collection and analysis in evaluating the effectiveness of inhospital CPR strategies. |
1,682 | Predictors of failure to cure atrial fibrillation with the mini-maze operation. | Maze-III is a complex surgical procedure designed to treat chronic atrial fibrillation. A reduction in the number of right and left atrial incisions could decrease the operative time. The aim of this study was to assess the results of a mini-maze operation and to define predictors of its failure.</AbstractText>Between 1995 and 2000, 72 patients (mean age 64 +/- 9 years) undergoing cardiac surgery had a concomitant mini-maze operation for symptomatic chronic atrial fibrillation. Three and 12 months post-operatively, heart rhythm and left atrial transport functions were assessed by electrophysiology, echocardiography, and magnetic resonance imaging. Multivariate analysis was performed to identify predictors of failure of the mini-maze operation.</AbstractText>Operative mortality was 1.4% (1/72). Death during follow-up occurred in 5.6% of patients (4/71), in one due to chronic heart failure. After 1 year, 80% of patients (48/60) were either in sinus rhythm (n = 43; 72%) or had a pacemaker (n = 5; 8%) implanted due to sick sinus syndrome. Intermittent and chronic atrial fibrillation was found in 20% of patients (12/60). Preoperative duration of atrial fibrillation (p = 0.05), preoperative left atrial diameter (p = 0.001), preoperative right atrial diameter (p = 0.02), a reduced left ventricular ejection fraction (p = 0.03), an increased left ventricular end-diastolic diameter (p = 0.04), and the presence of mitral valve stenosis (p = 0.001) were found to be univariate predictors of failure of the mini-maze operation 1 year postoperatively. Multivariate analysis defined preoperative diagnosis of mitral valve stenosis (p = 0.005; OR 117.5), longer duration of preoperative atrial fibrillation (p = 0.01; OR 1.33), and increased preoperative left ventricular end-systolic diameter (p = 0.02; OR 1.2) as incremental independent risk factors for failure of the mini-maze operation to cure chronic atrial fibrillation.</AbstractText>The mini-maze operation is a safe procedure with similar results to that of Cox's Maze-III operation. The less-invasive mini-maze operation could be applicable even to patients with severely reduced left ventricular function, in whom complex cardiac surgery has to be performed concomitantly as well as in those presenting severe comorbidities.</AbstractText> |
1,683 | [Obstructive respiration disorders during sleep and disorders of cardiac rhythm]. | To investigate the impact of obstructive sleep apnoea (OSA) on circadian profile of cardiac arrhythmia in patients with ischemic heart disease (IHD) and to determine clinical markers of OSA.</AbstractText>52 patients (31 males, 21 females, body mass index 30.5 +/- 5.8 kg/m2) with IHD admitted to hospital for ventricular extrasystole and paroxysmal cardiac fibrillation filled in questionnaires, were examined anthropometrically, with nocturnal cardiorespiration and holter monitoring. Cluster and correlation-regression mathematical analyses of the findings were made.</AbstractText>OSA was detected in 42 (80.8%) patients. Patients with primarily nocturnal arrhythmia, compared to those with diurnal arrhythmia had a significantly higher index apnea/hypopnea (29.2 and 21.5 vs 4.4, respectively), more pronounced fall in saturation (12.9 and 9.4% vs 4.9%, respectively) and lower body mass index. In 12 (23%) patients arrhythmia arose in parallel with episodes of sleep apnea/hypopnea. Mathematical analysis determined the following clinical markers of sleep respiratory disorders: regular intensive nocturnal snoring, body mass index > 25 kg/m2 and diurnal drowsiness > 15 scores by Epworth scale.</AbstractText>ORDS may provoke cardiac arrhythmia in patients with IHD.</AbstractText> |
1,684 | [Incidence of heart rate disorders in rural population of Krasnoiarsk region]. | To evaluate occurrence of heterotopic cardiac arrhythmia in rural population of the Krasnoyarsk Territory.</AbstractText>1203 persons (474 males, 729 females) aged 16 and older from rural population of the Krasnoyarsk Territory (the response rate 76.1%) filled in the questionnaires, have undergone ECG examination in 12 standard leads with continuos registration of 100 cardiocycles in one of the leads. Holter monitoring was conducted in 215 random examinees.</AbstractText>By ECG, the population was characterized by supraventricular extrasystole (SVE--8.9%), ventricular extrasystole (VE--6.4%) and cardiac fibrillation (1.5%). Overall, heterotopic disorders of heart rhythm were registered in 14.3% examinees. By Holter monitoring, heterotopic arrhythmia was detected much more often--in 68.4% examinees. SVE and VE occurred in 56.7 and 34.4%, respectively. Paroxysms of supraventricular tachyarrhythmia occurred in 10.2% cases.</AbstractText>In the examined population incidence of heterotopic arrhythmia and its variants increased with age. Incidence of heterotopic arrhythmias did not differ statistically between men and women, except VE which was encountered more often in males.</AbstractText> |
1,685 | [Prevention of recurrent amiodarone-induced hyperthyroidism by iodine-131]. | Amioradone-induced hyperthyroidism is a common complication of amiodarone therapy. Although definitive interruption of amiodarone is recommended because of the risks of aggravation of the arrhythmias, some patients may require the reintroduction of amiodarone several months after normalisation of thyroid function. The authors undertook a retrospective study of the effects of preventive treatment of recurrences of amiodarone-induced hyperthyroidism with I131. The indication of amiodarone therapy was recurrent, symptomatic, paroxysmal atrial fibrillation in 13 cases and ventricular tachycardia in 5 cases (M = 14, average age 64 +/- 13 years). The underlying cardiac disease was dilated cardiomyopathy (N = 5), ischaemic heart disease (N = 3), hypertensive heart disease (N = 2), arrhythmogenic right ventricular dysplasia (N = 2) or valvular heart disease (N = 2). Two patients had idiopathic atrial fibrillation. An average dose of 576 +/- 184 MBq of I131 was administered 34 +/- 37 months after an episode of amiodarone-induced hyperthyroidism. Amiodarone was reintroduced in 16 of the 18 patients after a treatment-free period of 98 +/- 262 days. Transient post-radioiodine hyperthyroidism was observed in 3 cases (17%). Sixteen patients (89%) developed hypothyroidism requiring replacement therapy with L-thyroxine. There were no recurrences of amiodarone-induced hyperthyroidism. After 24 +/- 17 months follow-up, the arrhythmias were controlled in 13 of the 16 patients (81%) who underwent the whole treatment sequence. The authors conclude that preventive treatment with I131 is an effective alternative to prevent recurrence of amiodarone-induced hyperthyroidism in patients requiring reintroduction of amiodarone to control their arrhythmias. |
1,686 | Dual chamber versus single chamber ventricular pacemakers for sick sinus syndrome and atrioventricular block. | Dual chamber pacing or single chamber atrial pacing ('physiologic' pacing) is believed to have an advantage over single chamber ventricular pacing in that it resembles cardiac physiology more closely by maintaining atrioventricular (AV) synchrony and dominance of the sinus node, which in turn may reduce cardiovascular morbidity and mortality thus contributing to patient survival and quality of life. However, a significant proportion of pacemakers currently implanted are single chamber ventricular pacemakers.</AbstractText>The objective of this review was to assess the short- and long-term clinical effectiveness of dual chamber pacemakers compared to single chamber ventricular pacemakers in adults with AV block, sick sinus syndrome or both. An additional objective was to assess separately any potential differences in effectiveness between dual chamber pacing and single chamber atrial pacing. The clinical effectiveness of single chamber atrial pacing versus single chamber ventricular pacing was not examined.</AbstractText>The Cochrane Controlled Trials Register (The Cochrane Library Issue 3, 2002), MEDLINE (1966 to 2002), EMBASE (1980 to 2002) and the Science Citation Index (1980 to 2002) were searched on 19th August 2002. Citation lists and web sites were checked and researchers in the field contacted.</AbstractText>Parallel group or crossover randomised controlled trials of at least 48 hours duration comparing dual chamber pacing and single chamber ventricular pacing, and investigating cardiovascular morbidity, mortality, patient related quality of life, exercise capacity and complication rates.</AbstractText>Data was extracted onto pre-piloted data extraction forms. Quality assessment was undertaken using a checklist, with a sub-sample of quality data independently extracted by a second reviewer. Where appropriate data was available, meta-analysis was performed. Where meta-analysis was not possible, the number of studies showing a positive, neutral or negative direction of effect and statistical significance were simply counted.</AbstractText>Five parallel and 26 crossover randomised controlled trials were identified. The quality of reporting was found to be poor. Pooled data from parallel studies shows a statistically non-significant preference for physiologic pacing (primarily dual chamber pacing) for the prevention of stroke, heart failure and mortality, and a statistically significant beneficial effect regarding the prevention of atrial fibrillation (odds ratio (OR) 0.79, 95% CI 0.68 to 0.93). Both parallel and crossover studies favour dual chamber pacing with regard to pacemaker syndrome (parallel: Peto OR 0.11, 95% CI 0.08 to 0.14; crossover: standardised mean difference (SMD) -0.74, 95% CI - 0.95 to -0.52). Pooled data from crossover studies shows a statistically significant trend towards dual chamber pacing being more favourable in terms of exercise capacity (SMD -0.24, 95% CI -0.03 to -0.45). No individual studies reported a significantly more favourable outcome with single chamber ventricular pacing.</AbstractText><AbstractText Label="REVIEWERS' CONCLUSIONS" NlmCategory="CONCLUSIONS">This review shows a trend towards greater effectiveness with dual chamber pacing compared to single chamber ventricular pacing, which supports the current British Pacing and Electrophysiology Group's Guidelines regarding atrioventricular block. Additional randomised controlled trial evidence from ongoing trials in this area will further inform the debate.</AbstractText> |
1,687 | Incidence of arrhythmic events in patients with implantable cardioverter-defibrillator for primary and secondary prevention of sudden cardiac death. | Implantable cardioverter-defibrillators (ICD) are increasingly used for prevention of sudden cardiac death (SCD). Although mortality risk reduction is about the same in primary and secondary prevention trials (~30%), we hypothesised that the incidence and the nature of ventricular arrhythmias is different in high risk ICD recipients without prior arrhythmias compared to patients who presented with life threatening arrhythmias.</AbstractText>A hundred consecutive ICD recipients were allocated to 2 groups: 1) secondary prevention: an ICD was implanted for secondary prevention of episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF). 2) primary prevention: patients at high risk of SCD without prior arrhythmias. They were prospectively followed and the incidence of appropriate ICD therapies was determined by reviewing stored electrograms.</AbstractText>During a mean follow-up of 20 (10) months, the overall mortality was 5% and 5% of the patients underwent heart transplantation. Of the 67 secondary prevention patients, 40% (n = 27) had VT/VF triggering ICD therapy, whereas only 15% (n = 5) of the 33 primary prevention patients had VT/VF triggering ICD therapy (p <0.05). The adjusted hazard ratio for arrhythmias triggering ICD interventions in the primary prevention group was 0.345 (95% confidence interval 0.132 to 0.902, p = 0.03).</AbstractText>The risk of developing arrhythmias triggering appropriate ICD intervention was 65% lower among the primary prevention patients than in secondary prevention patients. Importantly, ICD therapies are not correlated with lives saved, and efficacy of ICD therapy in primary and secondary prevention cannot be drawn from these data. However, the low incidence of ICD use in primary prevention patients emphasises that efforts should be made to develop better instruments for stratification.</AbstractText> |
1,688 | New sialyl-Lewis-X analogues antagonize leukocyte-induced ischemia-reperfusion arrhythmia--a mapping study. | Arrhythmia during ischemia and reperfusion is still an intriguing problem in cardiovascular medicine. Leukocytes infiltrating the ischemic region play an important pathophysiological role. The effects of soluble sialyl-Lewis-X analogues Hoe934553 and Hoe943644, which may inhibit leukocyte-endothelial interaction, were investigated.</AbstractText>Isolated rabbit hearts were perfused with Tyrode solution according to the Langendorff technique. Polymorphic neutrophilic granulocytes (PMN) were isolated from autologous peripheral blood. After 60 min equilibration PMN (n = 7) or vehicle (n = 7) were infused with or without concomitant treatment with Hoe934553 (n = 6) and Hoe943644 (n = 6). Five minutes after the start of the PMN infusion the left descending coronary artery was occluded for 30 min followed by 30 min of reperfusion. Activation and repolarization waves were recorded at 256 sites using a computerized mapping system.</AbstractText>Ventricular fibrillation (VF) in 4/7 PMN-treated hearts was found, while in PMN-free hearts no VF occurred. Treatment with Hoe934553 and Hoe943644 completely prevented VF. PMN largely enhanced the dispersion of action potential duration during reperfusion. This PMN effect was completely prevented by both drugs. Myeloperoxidase assay showed reduced activity in Hoe934553 and Hoe943644 treated hearts.</AbstractText>Sialyl-Lewis-X analogues (Hoe934553, Hoe943644) can antagonize PMN infiltration and PMN-induced VF in the course of ischemia and reperfusion.</AbstractText> |
1,689 | American Heart Association scientific sessions. | The Annual Scientific Sessions of the American Heart Association is the leading scientific conference in the cardiovascular field, both for basic and clinical research in cardiology and related disclipines. This report covers the outcome of major clinical trials that were presented in the 'late-breaking' clinical trial sessions. The Valsartan in Acute Myocardial Infarction Trial (VALIANT) investigated the angiotensin receptor blocker valsartan, the angiotensin-converting enzyme inhibitor captopril, and their combination in 14,703 survivors of an acute myocardial infarction with a reduced left ventricular ejection fraction on clinical outcome. The study demonstrated that valsartan and captopril where equally effective, whereas the combination was associated with an increased risk of side effects without further benefit. VALIANT is a landmark trial because it was the first large study that compared the combination of an angiotensin receptor blocker with an angiotensin-converting enzyme inhibitor in the setting of acute myocardial infarction. Other trials that will be summarised in this report are the Na + /H + Exchange Inhibition to Prevent Coronary Events in Acute Cardiac Conditions Trial (EXPEDITION; cariporide in coronary artery bypass graft surgery), the Reversal of Atherosclerosis with Aggressive Lipid Lowering Trial (REVERSAL; atorvastatin and pravastatin for atherosclerosis reversal), the Stroke Prevention Using an Oral Thrombin Inhibitor in Atrial Fibrillation V (SPORTIF V; ximelagatran and warfarin for stroke prevention in atrial fibrillation), the Prophylactic Amiodarone for the Prevention of Arrhythmias that Begin Early After Revascularisation (PAPABEAR; amiodarone for the prevention of postoperative atrial fibrillation), the Acute and Chronic Therapeutic Impact of a Vasopressin 2 Antagonist in Congestive Heart Failure (ACTIV in CHF; vasopressin 2 antagonist tolvaptan in congestive heart failure) and Prevention of Renal and Vascular Endstage Disease Intervention Trial (PREVEND IT; fosinopril and pravastatin in microalbuminuric subjects without hypertension or hypercholesterolemia). |
1,690 | Safety aspects for public access defibrillation using automated external defibrillators near high-voltage power lines. | Automated external defibrillators (AEDs) must combine easy operability and high-quality diagnosis even under unfavorable conditions. This study determined the influence of electromagnetic interference caused by high-voltage power lines with 16.7-Hz alternating current on the quality of AEDs' rhythm analysis.</AbstractText>Two AEDs frequently used in Austria were tested near high-voltage power lines (15 kV or 110 kV, alternating current with 16.7 Hz). The defibrillation electrodes were attached either to a proband with true sinus rhythm or to a resuscitation dummy with generated sinus rhythm, ventricular fibrillation, ventricular tachycardia or asystole.</AbstractText>Electromagnetic interference was much more prominent in a human's than in a dummy's electrocardiogram and depended on the position of the electrodes and cables in relation to the power line. Near high-voltage power lines the AEDs showed a significant operational fault. One AED interpreted the interference as a motion artifact, even when underlying rhythms were clearly detectable. The other AED interpreted 16.7-Hz oscillation as ventricular fibrillation with consequent shock advice when no underlying rhythm was detected.</AbstractText>The tested AEDs neither filter nor recognize a technical interference of 16.7 Hz caused by 15-kV power lines above railway tracks or 110-kV overland power lines, as run by railway companies in Austria, Germany, Norway, Sweden and Switzerland. These failures in AEDs' algorithms for rhythm analysis may cause substantial harm to patients undergoing public access defibrillation. The proper function of AEDs needs to be reconsidered to guarantee patients' safety near high-voltage power lines.</AbstractText> |
1,691 | The use of undiluted amiodarone in the management of out-of-hospital cardiac arrest. | The Resuscitation 2000 Guidelines recommends amiodarone as the antiarrhythmic drug of choice in treatment of resistant ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). Amiodarone has been associated with side-effects and difficulty of administration, due to recommended dilution, rendering it suboptimal for out-of-hospital cardiac arrest (CA) management. In the present study we report experiences and side-effects of the use of undiluted amiodarone in CA management in Helsinki Emergency Medical Service (EMS) during a 2-year period.</AbstractText>On October 1, the Resuscitation 2000 Guidelines were put into practice in Helsinki EMS. Thus, in the cardiac arrest treatment protocol, after three ineffective shocks and 1 mg of adrenaline (epinephrine), a bolus of 300 mg of undiluted amiodarone (Cordarone 50 mg ml(-1), Sanofi-Synthelabo, Helsinki, Finland) was administered into a vein located as centrally as possible. The Helsinki EMS performs systematic data collection according to the Utstein Guidelines. The blood pressure levels, heart rates and the need for vasopressors, of the patients with sustained return of spontaneous circulation (ROSC), were collected from the ambulance charts.</AbstractText>During October 1, 2000 and September 30, 2002, 712 patients were considered for resuscitation and 566 were resuscitated. The initial rhythms were as follows: 32% had VF/VT, 36% had asystole and 32% had pulseless electrical activity (PEA). Of the 180 patients with VF/VT, 75 (42%) received undiluted amiodarone in addition to other resuscitative measures. Of the patients with asystole or PEA, 12 (6%) and 18 (10%), respectively, received amiodarone. The blood pressure levels and the need vasopressors after ROSC and during transportation to the hospital were similar among the patients who received and those who did not receive amiodarone.</AbstractText>The present study suggests that amiodarone can be administered undiluted without unmanageable haemodynamical side-effects in the treatment of out-of-hospital cardiac arrest. This is likely to save time and simplifies the treatment protocol in the prehospital setting.</AbstractText> |
1,692 | Losartan but not enalaprilat acutely reduces reperfusion ventricular tachyarrhythmias in hypertrophied rat hearts after low-flow ischaemia. | Based on clinical and experimental studies, angiotensin II receptor blockers and angiotensin converting enzyme inhibitors have been proposed to exert acute anti-arrhythmic effects in heart failure patients. Therefore, the goal of this study was to assess acute anti-arrhythmic effects of losartan and enalaprilat in hypertrophied rat hearts during low-flow ischaemia and reperfusion. In dose-finding experiments in non-hypertrophied isolated perfused hearts, we performed dose-response curves of losartan and enalaprilat studying monophasic action potential duration at 90% repolarisation (MAPD(90%)) and ventricular fibrillation (VF) threshold. Subsequently, we determined the effects of losartan and enalaprilat (in therapeutically relevant concentrations) on ventricular tachyarrhythmias induced by low-flow ischaemia/reperfusion in hearts demonstrating left ventricular (LV) hypertrophy 70 days after aortic banding. We found that neither drug significantly affected MAPD(90%) (1 nM-1 mM) or VF threshold (1 microM losartan and 10 microM enalaprilat) in non-hypertrophied hearts. Similarly in hypertrophied hearts, neither drug significantly affected the incidence or the duration of ventricular tachyarrhythmias (ventricular tachycardia and VF) during low-flow ischaemia. However, 1 microM losartan significantly reduced the duration of ventricular tachyarrhythmias during reperfusion. In conclusion, neither losartan nor enalaprilat is acutely anti-arrhythmic in hypertrophied rat hearts during low-flow ischaemia. During reperfusion, however, losartan but not enalaprilat exerts acute anti-arrhythmic effects. |
1,693 | [Cerebral embolism associated with Becker muscular dystrophy-related dilated cardiomyopathy]. | A 65-year-old man with previous history of congestive heart failure and genetically proven Becker muscular dystrophy (BMD) was suddenly suffered from aphasia and right hemiplegia. Physical examination showed severe motor aphasia, right hemiplegia, and signs of left heart failure. An echocardiogram before the onset of aphasia showed markedly dilated left ventricle and decreased ventricular contraction. Intracardiac thrombus was not detected. Although his electrocardiogram on admission showed sinus rhythm, atrial fibrillation was noted at the time of neurological deterioration. MRI of the brain revealed acute infarction in the territory of the left middle cerebral artery and the left anterior inferior cerebellar artery. MR angiography showed vascular occlusion at the left M2 segment. Cerebral embolism due to atrial fibrillation associated with BMD-related DCM was diagnosed. While an administration of anti-coagulant, diuretics, and dopamine relieved his respiratory distress and right hemiplegia, severe motor aphasia persisted. Cerebral embolism may be a notable complication in patients with BMD presenting with late-life expression of skeletal muscular weakness and antecedent cardiac involvement. |
1,694 | Catecholaminergic polymorphic ventricular tachycardia: successful emergency treatment with intravenous propranolol. | Catecholaminergic polymorphic ventricular tachycardia (VT) is a rare arrhythmogenic disorder, which may cause sudden death and whose relationships with mutations in cardiac ryanodine receptor gene have been recently established. The present article reports a catecholaminergic polymorphic VT case of a 9-year-old girl, without any previous history of syncope, who has been found unconscious while playing and referred comatose to pediatric intensive care unit. The electrocardiogram pattern showed runs of bidirectional and polymorphic VT degenerating into ventricular fibrillation, without QT interval abnormalities. Various attempts of cardioversion, lidocaine, and magnesium sulfate intravenous infusions were only partially effective. Owing to catecholaminergic polymorphic VT highly suggesting electrocardiogram pattern, intravenous propranolol was administered, achieving immediate VT interruption. Long-term nadolol therapy effectively prevented further arrhythmias, with no relapses up to 10 months later; a good neurologic recovery was also obtained. Genetic evaluation revealed in this patient-but not in relatives-a mutation in ryanodine receptor gene on chromosome 1. |
1,695 | Gap junction alterations in human cardiac disease. | Gap junctions, assembled from connexins, form the cell-to-cell pathways for propagation of the precisely orchestrated patterns of current flow that govern the regular rhythm of the healthy heart. As in most tissues and organs, multiple connexin types are expressed in the heart; connexin43, connexin40 and connexin45 are found in distinctive combinations and relative quantities in different, functionally specialized subsets of cardiomyocyte. Alterations of gap junction organization and connexin expression are now well established as a consistent feature of human heart disease in which there is an arrhythmic tendency. These alterations may take the form of structural remodelling, involving disturbances in the distribution of gap junctions and/or alteration of the amount or type of connexin(s) expressed. In the diseased ventricles, the most consistent quantitative alteration involves heterogeneous reduction in connexin43 expression. In the atria, features of gap organization and connexin expression have been implicated in the initiation of atrial fibrillation and, once the condition becomes chronic, gap junction alterations associated with remodelling may contribute to persistence of the condition. By correlating data from studies on the human patient with those from animal and cell models, alterations in gap junctions and connexins have emerged as important factors to be considered in understanding the pro-arrhythmic substrate found in a variety of forms of heart disease. |
1,696 | Acute ischemia-induced gap junctional uncoupling and arrhythmogenesis. | Sudden cardiac death forms a major cause of mortality. Myocardial ischemia-induced ventricular fibrillation (VF) is frequently the underlying mechanism. Ventricular arrhythmias arise in two distinct phases during the first hour of ischemia. The first, the 1A phase, has been extensively studied, and few studies relate to the 1B phase. The latter is associated with intercellular electrical uncoupling, mediated by decreased conductance of gap junction channels. Although the relation between gap junctional uncoupling and decreased conduction velocity appears clear under normoxic conditions, additional factors contribute to conduction slowing during ischemia, and VF occurs preferentially at moderate levels of uncoupling. A potential mechanism of arrhythmias depends on temporary electrotonic depression of intrinsically viable tissue by the large bulk of the ischemic zone. This causes conduction slowing and conduction block in the surviving layers, leading to arrhythmias. These arrhythmias then resolve with progression of uncoupling. It is unknown whether either accelerated uncoupling or maintenance of gap junctional communication is antiarrhythmic. Ischemic preconditioning postpones both gap junctional uncoupling and occurrence of VF. Given the burden of sudden death and the large number of casualties in the low-risk population, there is, even in the era of implantable cardiac defibrillators, need for further understanding the mechanism of ischemia-induced VF. |
1,697 | Electrical storm as initial presentation of arrhytmogenic right ventricular cardiomyopathy in an elderly woman. | Arrhythmogenic right ventricular dysplasia (ARVD) is an unusual cause of electrical storm in the elderly. We report the case of a 76-year-old woman with no previous known disease who developed recurrent ventricular tachycardia and fibrillation. Postmortem examination revealed histological features of arrhythmogenic right ventricular dysplasia. |
1,698 | Short QT syndrome: pharmacological treatment. | The purpose of this study was to evaluate the efficacy of various antiarrhythmic drugs at prolonging the QT interval into the normal range and preventing ventricular arrhythmias in patients with short QT syndrome.</AbstractText>Short QT syndrome is a recently described genetic disease characterized by short QT interval, high risk of sudden death, atrial fibrillation, and short refractory periods.</AbstractText>Six patients with short QT syndrome, five of whom had received an implantable cardioverter-defibrillator (ICD) and one child, were tested with different antiarrhythmic drugs, including flecainide, sotalol, ibutilide, and hydroquinidine, to determine whether they could prolong the QT interval into the normal range and thus prevent symptoms and arrhythmia recurrences.</AbstractText>Class IC and III antiarrhythmic drugs did not produce a significant QT interval prolongation. Only hydroquinidine administration caused a QT prolongation, which increased from 263 +/- 12 ms to 362 +/- 25 ms (calculated QT from 290 +/- 13 ms to 405 +/- 26 ms). Ventricular programmed stimulation showed prolongation of ventricular effective refractory period to > or =200 ms, and ventricular fibrillation was no longer induced.</AbstractText>The ability of quinidine to prolong the QT interval has the potential to be an effective therapy for short QT patients. This is particularly important because these patients are at risk of sudden death from birth, and ICD implant is not feasible in very young children.</AbstractText> |
1,699 | Calcium chloride before i.v. diltiazem in the management of atrial fibrillation. | Diltiazem is commonly used to treat atrial fibrillation or flutter (AFF) with rapid ventricular response (RVR). Although it is very effective for rate control, up to an 18% prevalence of reported diltiazem-induced hypotension [defined by systolic blood pressure (SBP) < 90 mm Hg], and a mean of 9.7% hypotension have been reported from several studies totaling over 450 patients. This hypotension may complicate therapy. Our objective was to determine if calcium chloride (CaCl(2)) pre-treatment would blunt a SBP drop after i.v. diltiazem, while allowing diltiazem to maintain its efficacy. A prospective, randomized, double-blind, placebo-controlled study was conducted. Seventy-eight patients with AFF and a ventricular rate of >/= 120 beats per minute were enrolled. Half received i.v. CaCl(2) pre-treatment; the other half received placebo. All patients then received i.v. diltiazem in a standard, weight-based dose. A second dose of CaCl(2) pre-treatment or placebo and diltiazem was given if clinically indicated for additional rate control. Both CaCl(2) and placebo pre-treatment groups had equal lowering of heart rate (p < 0.001). There were no adverse events in the calcium pre-treatment study arm. One patient in the placebo group became paradoxically more tachycardic and apneic after the diltiazem infusion. Although i.v. CaCl(2) seems to be equally safe compared to placebo as a pre-treatment in the management of AFF with RVR, we were unable to find a statistically significant blunting of SBP drop with CaCl(2) i.v. pre-treatment. Until further research determines a benefit exists, we cannot recommend i.v. CaCl(2) pre-treatment before diltiazem in the treatment of AFF with RVR. |
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