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15,400 | Association of decreased left atrial strain and strain rate with stroke in chronic atrial fibrillation. | The objective of this study was to investigate myocardial deformation of the left atrium (LA) assessed by two-dimensional speckle tracking echocardiography in patients with permanent atrial fibrillation (AF) and its value for risk stratification for stroke.</AbstractText>We recruited 66 consecutive patients with permanent AF who were referred to our echocardiography laboratory for evaluation. These patients were divided into two groups according to the presence of previous stroke or not.</AbstractText>Peak positive longitudinal strain (LASp) during atrial filling, peak strain rate in the reservoir phase of LA (LASRr), and peak strain rate in the conduit phase (LASRc) were identified from LA strain and strain rate curves. The ratio of peak early filling velocity (E) of mitral inflow to early diastolic annulus velocity (E') of the medial annulus (E/E') was calculated. LASp (10.44% ± 4.2% vs. 15.69% ± 5.1%, P < .001), LASRr (1.09 ± 0.27 1/s vs. 1.37 ± 0.32 1/s, P = .001), and LASRc (-1.28 ± 0.38 1/s vs. -1.62 ± 0.43 1/s, P = .002) were significantly lower in patients with AF with stroke than those without stroke. By multivariate analysis controlling for age, LA volume index, and left ventricular ejection fraction, LASp (OR 0.787, 95% CI, 0.639-0.968, P = .023) and LASRr (OR 0.019, 95% CI, 0.001-0.585, P = .023) were independently associated with stroke but not LASRc, E', and E/E' ratio.</AbstractText>Decreased LASp and LASRr were independently associated with stroke in patients with permanent AF.</AbstractText>Copyright © 2011 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.</CopyrightInformation> |
15,401 | Assessment of atrial conduction time in patients with essential hypertension. | We aimed to assess atrial conduction time in patients with essential hypertension.</AbstractText>A total of 80 patients with hypertension (51 males/29 females, 53 ± 12.5 years) and 80 controls (50 males/30 females, 50 ± 12 years) were included. Atrial electromechanical coupling (time interval from the onset of P wave on surface electrocardiogram [ECG] to the beginning of A wave interval with tissue Doppler echocardiography [PA]), intraatrial and interatrial electromechanical delay (intra and inter atrial electromechanical delay [AEMD]), and P-wave dispersion (Pd) were measured (Appelton, C.P., Hatle, L., Popp, R.L., Relation of transmitral flow velocity patterns to left ventricular diastolic function: new insights from combined hemodynamic and Doppler echocardiographic study. J Am Coll Cardiol. 1988; 12: 426-440).</AbstractText>Atrial electromechanical coupling at the left lateral mitral annulus (PA lateral) and septal mitral annulus were longer in patients with hypertension (63.0 ± 8.0 vs 50.2 ± 4.3, P < .001, and 53.3 ± 6.2 vs 40.1 ± 5.5, P < .001). Interatrial (PA lateral-PA tricuspid) and intraatrial electromechanical delay (PA septum-PA tricuspid) were longer in patients with hypertension (24.8 ± 7.2 vs 12.4 ± 4.3, P < .001, and 14.1 ± 4.5 vs 2.3 ± 1.6, P < .001, respectively). Maximum P-wave duration and Pd were higher in patients with hypertension compared with controls (95.6 ± 8.0 vs 90.1 ± 9.5, P = .01, and 41.3 ± 7.1 vs 33.5 ± 6.1 P < .001, respectively). In correlation analysis, a positive correlation was detected between interatrial electromechanical delay and Pd (r = 0.72, P < .001). There was a moderate correlation between left ventricular mass index and PA lateral (r = 0.48, P < .001).</AbstractText>Our results revealed that interatrial electromechanical delay and Pd were prolonged in patients with hypertension. Our results also showed a correlation between interatrial electromechanical delay and Pd. Prolonged electromechanical delay and Pd found in hypertensive patients could be related with increased incidence of atrial fibrillation in these patients. Prospective studies are needed to document the association between intraatrial and interatrial electromechanical delays and the development of atrial fibrillation.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,402 | Heart rate turbulence in postinfarction patients with history of malignant ventricular arrhythmias. | In the study, there has been retrospectively analyzed heart rate turbulence in postinfarction patients. The cohort of 158 patients consisted of 94 patients with documented ventricular tachycardia and/or ventricular fibrillation (VT/VF) and 64 patients without history of VT/VF. Turbulence onset and slope were calculated from Holter recordings, and left ventricle ejection fraction (LVEF) ≤35% was regarded as severe left ventricle dysfunction. Study groups were similar in age and sex. Left ventricle ejection fraction was lower in the VT/VF group (P < .005). Patients with VT/VF had higher turbulence onset (-0.22% ± 1% vs -0.8% ± 2%; P = .005) and lower turbulence slope (2.6 ± 1.9 vs 4.1 ± 3.5 milliseconds per RR interval; P = .01). These trends were observed in patients with LVEF >35% but not in subjects with LVEF ≤35%. Diabetes mellitus, previous coronary artery bypass graft, and amiodarone therapy have diminished the intergroup differences significantly.</AbstractText>Heart rate turbulence is diminished in postinfarction patients with a history of malignant ventricular arrhythmias. It seems to separate subjects at arrhythmic risk among patients with relatively preserved left ventricle function, but it is diminished in patients with previous coronary artery bypass graft, diabetes, and amiodarone therapy.</AbstractText>Copyright © 2011 Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,403 | Treating arrhythmias: an expert opinion. | Significant progress has recently been made in the pharmacological treatment of arrhythmias. This concerns mainly atrial fibrillation, which affects millions of patients.</AbstractText>This review covers recent, clinically relevant developments in arrhythmia treatment, especially with regard to novel agents for the management of atrial fibrillation: dronedarone for rhythm control, vernakalant for pharmacological conversion, and advances in antithrombotic treatment. The field of pharmacological treatment of ventricular arrhythmias is also briefly discussed. Relevant papers were identified by an extensive Pubmed search using appropriate keywords.</AbstractText>Dronedarone has been proposed as one of the first-choice antiarrhythmic drugs for almost all categories of patients with atrial fibrillation. However, its effectiveness in prevention of arrhythmia recurrences is less than that of amiodarone. Administration to patients with severe heart failure is associated with increased mortality and should be avoided. There are also very recent reports over rare but severe cases of hepatic injury in patients treated with dronedarone, including two cases of acute liver failure leading to liver transplant. Intravenous vernakalant is effective for the rapid pharmacological conversion of atrial fibrillation. Dabigatran, an oral direct thrombin inhibitor, has been shown to be effective in stroke reduction without increase in bleeding rates; additionally, no monitoring of antithrombotic effectiveness is needed. Rivaroxaban, an oral direct factor Xa inhibitor, has also shown promising results. These developments in the pharmacological treatment of arrhythmia will presumably affect clinical decision making.</AbstractText> |
15,404 | Emerging antiarrhythmic agents: a personal view from the Far East. | Arrhythmia treatments today take three different approaches. One uses electronic devices, such as electronic pacemakers or defibrillators, and this is regarded as life-saving in cases of bradyarrhythmias and ventricular fibrillation. Another is the ablation technique which eliminates abnormal pacemakers and/or conductive pathways by applying thermal or cryo-injury to pathological portions of the heart. The most classical one is the antiarrhythmic drugs, but are they effective and safe?</AbstractText>Recent development of the understanding of arrhythmias, cardiac ionic channels and antiarrhythmic drugs covered by papers mostly published after 2000 are discussed.</AbstractText>The market size of the antiarrhythmic drugs is small, but various multichannel acting drugs may become candidates as antiarrhythmic drugs. As the cardiac ionic channels have become recognized as proteins, the molecular target for antiarrhythmic drugs has become apparent, but at the same time accurate data on clinical effectiveness and safety are required for drug approval; thus, few atrium selective drugs, such as IKur, IKACh and IKAde blocking drugs and amiodarone-like multichannel acting drugs are being developed.</AbstractText> |
15,405 | [Why there is atrial fibrillation after cardiac operations?]. | Atrial fibrillation (AF) is the most frequent arrhythmias after cardiac operations. Its incidence ranges from 10-65%. Often there is a patient discomfort, prolongs hospitalization, increases costs of operation and may be permanent or recurrent course. The cause of postoperative AF is multifactorial. The prevention of non-pharmacological and pharmacological interventions. The conventional treatment strategies include monitoring ventricular rate, restoration of sinus rhythm and prevention of thromboembolic events. The development of effective therapies designed to decrease the high incidence of postoperative AF may be important in the future. |
15,406 | [Therapeutic hypothermia after non-traumatic cardiac arrest for 12 hours: Hospital Karlovy vary from 2006 to 2009]. | Therapeutic hypothermia is a standard part of post-resuscitation care. Here we present cohort patients after non-traumatic cardiac arrest and their neurological outcomes who underwent 12 hours of therapeutic hypothermia. Moreover, we focused on examining the results of particular subgroup of patients with initial ventricular fibrillation (VF) with acute myocardial infarction with ST-elevation (STEMI) who underwent coronary intervention (PCI).</AbstractText>We evaluated retrospectively the patients with non-traumatic out-of- and in-hospital cardiac arrest (IHCA, OHCA), admitted to our intensive care unit (ICU) in 2006-2009. Therapeutic hypothermia was induced in all patients with persistent coma after restoration of spontaneous circulation (ROSC). We maintained the target temperature (32-34 degrees C) for 12 hours. Then, passive rewarming followed. Intravascular cooling device was not used. A good neurological outcome was considered to be cerebral performance category (CPC) 1 or 2 at hospital discharge.</AbstractText>Total number of patients was 88 (OHCA n = 63; IHCA n = 25), average age 58 (+/- 16) years, average APACHE II was 29 (+/- 6). Men were in 65%. Target temperature was achieved and maintained in 76% of patients. ICU mortality was 32%, hospital mortality 53%. Initial ECG rhythm was VF in 59%, asystoly in 32% and pulsless electrical activity in 9%. Coronary angiography was performed in 57% and PCI in 42% patients. We did not observe severe arrhythmias, minor gastrointestinal bleeding occurred in 2%. The infectious complications were recorded: early pneumonia in 7%, tracheobronchitis in 10% and bacteraemia in 1% patients. In the group of 23 patients with VF/STEMI/PCI target temperature was achieved and maintained in 91%, ICU and hospital survival rates were 87% and 78%. CPC 1 and 2 was observed in 83% among survivors (n = 15).</AbstractText>We achieved similar results in patients after non-traumatic cardiac arrest who underwent a protocol with 12 hours of therapeutic hypothermia as in studies reporting 24 hours of hypothermia, particularly in patients with VF/STEMI/PCI. Twelve hours of therapeutic hypothermia was associated with a low incidence of infectious complications.</AbstractText> |
15,407 | Successful primary percutaneous coronary intervention in the first trimester of pregnancy. | A 28-year-old patient, medical nurse, in 10th week of her second pregnancy suffered ventricular fibrillation just after entering the waiting room of the emergency department. After she was successfully defibrillated, electrocardiography revealed a large acute anteroseptolateral ST elevation myocardial infarction. Urgent coronarography was done (premedication with 300 mg of aspirin and 600 mg of clopidogrel) with 90 min door-to-balloon time. Proximal left anterior descending occlusion was found, primary percutaneous coronary intervention was done using Amazonia CroCo 3.0/12 bare-metal stent, and Thrombolysis in Myocardial Infarction III flow was achieved. During the procedure, the patient was wrapped in lead apron. Because of postresuscitational agitation, procedure was done in intravenous anesthesia. The revealed risk factors were smoking and hypercholesterolemia. PAI-1 gene 4G/4G genotype and Apo E gene E2/E4 genotype were also found. Estimated X-ray dosage that fetus received during the procedure was 0.45 mSv, which is less than the upper safe limit in pregnancy. All drugs given to our patient (clopidogrel, aspirin, ivabradine, bisoprolol, anesthetics, low-molecular-weight heparin, and unfractionated heparin) have B or C Food and Drug Administration Pregnancy Category. Fetal ultrasonography showed normal fetal growth, and, after consultation with our team, the patient decided to maintain the pregnancy. Before discharge echocardiography showed left ventricle of normal size with anteroseptolateral hypokinesia, small apical aneurysm, left ventricular ejection fraction of 40-45%, and diastolic dysfunction grade II, without pulmonary hypertension. At the 36th week of pregnancy, the patient was hospitalized and closely monitored; clopidogrel and aspirin were discontinued, and low-molecular-weight heparin was administered. She gave birth to a normal boy by vaginal delivery with epidural anesthesia and without any complication. |
15,408 | Small-conductance calcium-activated potassium channel and recurrent ventricular fibrillation in failing rabbit ventricles. | Fibrillation/defibrillation episodes in failing ventricles may be followed by action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (SVF).</AbstractText>We hypothesized that activation of apamin-sensitive small-conductance Ca(2+)-activated K(+) (SK) channels is responsible for the postshock APD shortening in failing ventricles.</AbstractText>A rabbit model of tachycardia-induced heart failure was used. Simultaneous optical mapping of intracellular Ca(2+) and membrane potential (V(m)) was performed in failing and nonfailing ventricles. Three failing ventricles developed SVF (SVF group); 9 did not (no-SVF group). None of the 10 nonfailing ventricles developed SVF. Increased pacing rate and duration augmented the magnitude of APD shortening. Apamin (1 μmol/L) eliminated recurrent SVF and increased postshock APD(80) in the SVF group from 126±5 to 153±4 ms (P<0.05) and from 147±2 to 162±3 ms (P<0.05) in the no-SVF group but did not change APD(80) in nonfailing group. Whole cell patch-clamp studies at 36°C showed that the apamin-sensitive K(+) current (I(KAS)) density was significantly larger in the failing than in the normal ventricular epicardial myocytes, and epicardial I(KAS) density was significantly higher than midmyocardial and endocardial myocytes. Steady-state Ca(2+) response of I(KAS) was leftward-shifted in the failing cells compared with the normal control cells, indicating increased Ca(2+) sensitivity of I(KAS) in failing ventricles. The K(d) was 232±5 nmol/L for failing myocytes and 553±78 nmol/L for normal myocytes (P=0.002).</AbstractText>Heart failure heterogeneously increases the sensitivity of I(KAS) to intracellular Ca(2+), leading to upregulation of I(KAS), postshock APD shortening, and recurrent SVF.</AbstractText> |
15,409 | Acute myocardial infarction: high risk ventricular tachyarrhythmias and admission glucose level in patients with and without diabetes mellitus. | The aim of this study was to evaluate the impact of glucose levels on admission and High Risk Ventricular Tachyarrhythmia (HRVT) in hospital mortality in patients with Acute Myocardial Infarction (AMI).</AbstractText>We studied 1.258 consecutive patients admitted to the Coronary Care Unit with a diagnosis of AMI. Ventricular Fibrillation, sustained and nonsustained Ventricular Tachycardia were considered as HRVT. Association between admission glucose, in-hospital mortality and HRVT was assessed with Cox regression analysis.</AbstractText>The overall incidence of in-hospital HRVT was 20% (254/1258 patients) and in-hospital mortality (115/1.258) was higher in patients with HRVT (20% vs 6%) (p< 0.001). Diabetes Mellitus (DM) was present in 441 patients (35%). Optimal threshold level of glycemia admission to predict ventricular arrhythmia was 180 mg/dl (AUC = 0.716; 0.66- 0.76)(p<0.001). Patients with euglycemia on admission (< 120 mg/dL) had lowest prevalence of HRVT (13%)(OR=0.6;0.46-0.78) in contrast to non DM patients who presented glucose 180 mg/dL that exhibited 2-fold increase of in-hospital HRVT (36%; OR=2.2; 1.6-3)(p<0.001). Multivariate risk adjusted hazard ratio (HR) analysis showed that, blood pressure < 100 mmHg (HR=2.4; 1.6-3.6)(p<0.001), White Blood Count (WBC)>10.000 cell count (HR=1.44;1.02-2)(p=0.04) and admission glycemia 180 mg/dL (HR=1.5; 1.04-2.3)( p=0.03) had a significantly increased risk in in-hospital HRTV only in NDM patients.</AbstractText>The higher glycemia on admission the higher prevalence of life-threatening arrhythmia and mortality regardless diabetes status in patients presenting with AMI. Elevated initial glucose level and WBC count considered along with other clinical data can assist in life-threatening ventricular arrhythmia in non diabetic patients.</AbstractText> |
15,410 | [Case of cardiac arrest due to coronary spasm during laparoscopic distal gastrectomy]. | We describe a 50-year-old man who developed ventricular arrhythmia followed by cardiac arrest during laparoscopic distal gastrectomy. Preoperatively, there were no findings suggesting an ischemic heart disease. Anesthesia was maintained using sevoflurane combined with epidural anesthesia. His blood pressure, heart rate, and ECG waves were stable during the initial stage of laparoscopic procedure. After establishment of small laparotomy for stomach resection, the blood pressure decreased to before 60 mmHg without remarkable ST change on lead II. Administration of intravenous ephedrine was not effective and a short run appeared. Then persistent ventricular tachycardia followed by ventricular standstill developed. Chest compression and intravenous adrenalin restored sinus rhythm, and thereafter the patient remained hemodynamically stable with intravenous nitroglycerine and nicorandil. The operation was completed and the patient awoke without neurological deficits. Postoperatively the coronary angiography showed no stenosis of coronary arteries; however, when acetylcholine test was attempted on right coronary artery, paroxysmal ventricular fibrillation in accordance with spasm of #1 segmental coronary artery developed. In the case of abrupt onset of lethal arrhythmia, coronary vasospasm should be suspected even when ST changes are not recognized with routine ECG monitor. |
15,411 | Drug-induced QTC prolongation dangerously underestimates proarrhythmic potential: lessons from terfenadine. | Terfenadine's proarrhythmia prompted market withdrawal; therapeutic antihistaminic concentration is less than 1 nM, whereas IC50 of IKr and INa exceed 200 nM.</AbstractText>Rabbit hearts were perfused with terfenadine (1-10,000 nM; 10-450 minutes). A dosage of 1 nM tended to shorten action potential duration (APD60) (-30 ± 30.5 ms; n = 6); 10 nM (450 minutes) significantly prolonged APD60 (46 ± 11 ms; n = 6), but after 1 hour washout, APD60 further prolonged. Above 30 nM, APD60 shortening was followed by prolongation; net effect depended on exposure time (n = 33). In the μM range, cardiac wavelength (λ) shortened (APD60 shortened, conduction slowed; P < 0.05). Terfenadine induced triangulation, reverse use dependence, instability and dispersion of repolarization (TRIaD) at 1 to 1000 nM, increasing with concentration (450 minutes: 1 nM yielded 50% of hearts, 10 nM 100%) and exposure (100 nM: 10 minutes yielded 16%, 30 minutes 33%, 150 minutes 66%, 450 minutes 100%). TRIaD with APD prolongation preceded two Torsade de Pointes, with shortening seven ventricular tachycardia and five ventricular fibrillation. Terfenadine causes normally little QTc prolongation in patients and Food and Drug Administration records suggest that incidence of ventricular tachycardia/ventricular fibrillation exceeds Torsade de Pointes.</AbstractText>For terfenadine, TRIaD predicts drug-induced proarrhythmia: with λ prolongation, Torsade de Pointes is preferred, otherwise ventricular tachycardia/ventricular fibrillation. APD/QTc alone is clearly inadequate for proarrhythmia evaluation.</AbstractText> |
15,412 | Upstream therapies for management of atrial fibrillation: review of clinical evidence and implications for European Society of Cardiology guidelines. Part I: primary prevention. | Atrial fibrillation (AF) is associated with significant morbidity and mortality. It is also a progressive disease secondary to continuous structural remodelling of the atria due to AF itself, to changes associated with ageing, and to deterioration of underlying heart disease. Current management aims at preventing the recurrence of AF and its consequences (secondary prevention) and includes risk assessment and prevention of stroke, ventricular rate control, and rhythm control therapies including antiarrhythmic drugs and catheter or surgical ablation. The concept of primary prevention of AF with interventions targeting the development of substrate and modifying risk factors for AF has emerged as a result of recent experiments that suggested novel targets for mechanism-based therapies. Upstream therapy refers to the use of non-antiarrhythmic drugs that modify the atrial substrate- or target-specific mechanisms of AF to prevent the occurrence or recurrence of the arrhythmia. Such agents include angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), statins, n-3 (ω-3) polyunsaturated fatty acids, and possibly corticosteroids. Animal experiments have compellingly demonstrated the protective effect of these agents against electrical and structural atrial remodelling in association with AF. The key targets of upstream therapy are structural changes in the atria, such as fibrosis, hypertrophy, inflammation, and oxidative stress, but direct and indirect effects on atrial ion channels, gap junctions, and calcium handling are also applied. Although there have been no formal randomized controlled studies (RCTs) in the primary prevention setting, retrospective analyses and reports from the studies in which AF was a pre-specified secondary endpoint have shown a sustained reduction in new-onset AF with ACEIs and ARBs in patients with significant underlying heart disease (e.g. left ventricular dysfunction and hypertrophy), and in the incidence of AF after cardiac surgery in patients treated with statins. In the secondary prevention setting, the results with upstream therapies are significantly less encouraging. Although the results of hypothesis-generating small clinical studies or retrospective analyses in selected patient categories have been positive, larger prospective RCTs have yielded controversial, mostly negative, results. Notably, the controversy exists on whether upstream therapy may impact mortality and major non-fatal cardiovascular events in patients with AF. This has been addressed in retrospective analyses and large prospective RCTs, but the results remain inconclusive pending further reports. This review provides a contemporary evidence-based insight into the role of upstream therapies in primary (Part I) and secondary (Part II) prevention of AF. |
15,413 | [Sleep disordered breathing and cardiac arrhythmias: mechanisms, interactions, and clinical relevance]. | In patients with cardiac disease growing interests have been centered on concomitant co-morbidities such as sleep disordered breathing (SDB). Obstructive sleep apnoea (OSA) as well as Cheyne-Stokes Respiration (CSR) have been recognized as relevant co-morbidities that are highly prevalent and associated with an impaired prognosis. As a known consequence from recurrent hypoxaemias and an increased sympathetic activity, SDB promotes structural myocardial changes and potentially triggers cardiac arrhythmias. Several investigations thus reported an increasing frequency of cardiac arrhythmias among patients with either OSA or CSR. Sufficiently suppressing SDB by adequate therapies seems to ameliorate its arrhythmogenic impact. However, especially for CSR data from randomized, controlled trial are urgently awaited to definitely answer this question. |
15,414 | The diagnosis and management of ventricular arrhythmias. | The term 'ventricular arrhythmias' incorporates a wide spectrum of abnormal cardiac rhythms, from single premature ventricular complexes to sustained monomorphic ventricular tachycardia (VT), polymorphic VT, and ventricular fibrillation. Sustained ventricular arrhythmias are the most common cause of sudden cardiac death. These arrhythmias occur predominantly in patients with structural heart disease, but are also seen in patients with no demonstrable cardiac disease. The diagnosis of VT can be made reliably using electrocardiographic criteria, and a number of algorithms have been proposed. Among patients with VT and a structurally normal heart, the prognosis is usually benign and treatment is predominantly focused on the elimination of symptoms. Patients who have VT in the presence of structural heart disease are often managed with implantable cardioverter-defibrillators. These devices are effective for both primary and secondary prevention of VT and sudden cardiac death. Pharmacological therapy for VT has limited efficacy and is associated with a high incidence of adverse effects. Radiofrequency catheter ablation is useful for controlling recurrent episodes of monomorphic VT; however, research is needed to define the role of catheter ablation in the treatment of other ventricular arrhythmias. |
15,415 | The follow-up evaluation of electrocardiogram and arrhythmias in children with fulminant myocarditis. | Fulminant myocarditis involves various serious arrhythmias that sometimes have lethal consequences. The purpose of the present study was to investigate the electrocardiogram findings, arrhythmogenicity and abnormalities of the cardiac conduction system in children with fulminant myocarditis.</AbstractText>Between 1999 and 2008, 7 consecutive patients (mean age: 7 years) who suffered from fulminant myocarditis were included in the study. A 12-lead electrocardiogram, Holter monitoring and signal-averaged electrocardiograms were performed and compared between the acute, convalescent, and recovery phases in the 4 surviving patients. Also, electrophysiologic assessment was carried out during the convalescent phase. Five out of 7 patients developed complete atrioventricular block, 3 developed ventricular tachycardia, 2 had cardiac arrest, 2 developed sinus tachycardia, 1 developed ventricular fibrillation, 1 had advanced atrioventricular block, and 1 developed sick sinus syndrome. Among the surviving patients, all arrhythmias resolved during the convalescent and remote phases. No atrial or ventricular arrhythmias were induced in any patients during the programmed stimulation study. In the convalescent phase, no arrhythmias could be induced and there were no signs of any conduction abnormalities on electrophysiological assessment.</AbstractText>Close follow-up should be performed to observe for the occurrence of any new arrhythmias and/or a decrease in cardiac function in children with fulminant myocarditis.</AbstractText>All rights are reserved to the Japanese Circulation Society.</CopyrightInformation> |
15,416 | An algorithm used for ventricular fibrillation detection without interrupting chest compression. | Ventricular fibrillation (VF) is the primary arrhythmic event in the majority of patients suffering from sudden cardiac arrest. Attention has been focused on this particular rhythm since it is recognized that prompt therapy, especially electrical defibrillation, may lead to a successful outcome. However, current versions of automated external defibrillators (AEDs) mandate repetitive interruptions of chest compression for rhythm analyses since artifacts produced by chest compression during cardiopulmonary resuscitation (CPR) preclude reliable electrocardiographic (ECG) rhythm analysis. Yet, repetitive interruptions in chest compression are detrimental to the success of defibrillation. The capability for rhythm analysis without requiring "hands-off" intervals will allow for more effective resuscitation. In this paper, a novel continuous-wavelet-transformation-based morphology consistency evaluation algorithm was developed for the detection of disorganized VF from organized sinus rhythm (SR) without interrupting the ongoing chest compression. The performance of this method was evaluated on both uncorrupted and corrupted ECG signals recorded from AEDs obtained from out-of-hospital victims of cardiac arrest. A total of 232 patients and 31,092 episodes of either VF or SR were accessed, in which 8195 episodes were corrupted by artifacts produced by chest compressions. We also compared the performance of this method with three other established algorithms, including VF filter, spectrum analysis, and complexity measurement. Even though there was a modest decrease in specificity and accuracy when chest compression artifact was present, the performance of this method was still superior to other reported methods for VF detection during uninterrupted CPR. |
15,417 | Unmappable ventricular tachycardia after an old myocardial infarction. Long-term results of substrate modification in patients with an implantable cardioverter defibrillator. | The frequent occurrence of ventricular tachycardia can create a serious problem in patients with an implantable cardioverter defibrillator. We assessed the long-term efficacy of catheter-based substrate modification using the voltage mapping technique of infarct-related ventricular tachycardia and recurrent device therapy.</AbstractText>The study population consisted of 27 consecutive patients (age 68 ± 8 years, 25 men, mean left ventricular ejection fraction 31 ± 9%) with an old myocardial infarction and multiple and/or hemodynamically not tolerated ventricular tachycardia necessitating repeated device therapy. A total of 31 substrate modification procedures were performed using the three-dimensional electroanatomical mapping system. Patients were followed up for a median of 23.5 (interquartile range 6.5-53.2) months before and 37.8 (interquartile range 11.7-71.8) months after ablation. Antiarrhythmic drugs were not changed after the procedure, and were stopped 6 to 9 months after the procedure in patients who did not show ventricular tachycardia recurrence.</AbstractText>Median ventricular tachycardias were 1.6 (interquartile range 0.7-6.7) per month before and 0.2 (interquartile range 0.00-1.3) per month after ablation (P = 0.006). Nine ventricular fibrillation episodes were registered in seven patients before and two after ablation (P = 0.025). Median antitachycardia pacing decreased from 1.6 (interquartile range 0.01-5.5) per month before to 0.18 (interquartile range 0.00-1.6) per month after ablation (P = 0.069). Median number of shocks decreased from 0.19 (interquartile range 0.04-0.81) per month before to 0.00 (interquartile range 0.00-0.09) per month after ablation (P = 0.001). One patient had a transient ischemic attack during the procedure, and another developed pericarditis. Nine patients died during follow-up, eight patients due to heart failure and one patient during valve surgery.</AbstractText>Catheter-based substrate modification using voltage mapping results in a long-lasting reduction of cardioverter defibrillator therapy in patients with multiple and/or hemodynamically not tolerated infarct-related ventricular tachyarrhythmia.</AbstractText> |
15,418 | Coronary artery disease affecting the atrial branches is an independent determinant of atrial fibrillation after myocardial infarction. | During acute myocardial infarction (MI), the incidence of atrial fibrillation (AF) is 6% to 22%, and its occurrence in this setting is associated with increased short- and long-term morbidity and mortality.</AbstractText>The purpose of this case control study was evaluate the characteristics associated with the development of new-onset AF.</AbstractText>Of 2,460 consecutive patients with acute MI, 149 (6%) were identified as having AF within 7 days of MI. After excluding patients with prior AF, previously documented heart failure, reduced left ventricular (LV) ejection fraction, valvular heart disease, LV hypertrophy, AF after coronary artery bypass grafting, or pericarditis; we identified 42 AF patients in whom coronary anatomy was assessed by invasive angiography and cardiac structure and function was evaluated using transthoracic echocardiography. Another 42 patients from the same cohort with MI but no AF matched for age, gender, and LV ejection fraction were studied as controls.</AbstractText>AF patients were more likely to present with an inferior MI (P = .002) but less likely to present with ST-segment elevation MI (P = .02). Univariate associations with AF included indexed left atrial volume (P <.001), LV filling pressure (E/e'; P = .001), right atrial branch disease (P <.001), left atrial branch disease (P = .009), sinoatrial branch disease (P <.001), left main stem disease (P = .02), and time from onset of symptoms to coronary intervention (P = .002). In multivariable analysis, right and left coronary artery atrial branch disease (P = .02) were predictors of AF post-MI.</AbstractText>Coronary artery disease affecting the atrial branches is an independent predictor for the development of AF after MI.</AbstractText>Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,419 | Outcomes of cardiac resynchronization therapy in patients with versus those without atrial fibrillation: a systematic review and meta-analysis. | Whether the benefits observed with cardiac resynchronization therapy (CRT) are similar in patients with versus those without atrial fibrillation (AF) is unclear. Furthermore, whether patients with AF receiving CRT should undergo atrioventricular nodal (AVN) ablation remains uncertain.</AbstractText>The purpose of this study was to compare outcomes in patients with and those without AF receiving CRT and to evaluate the influence of AVN ablation on outcomes in patients with AF.</AbstractText>A systematic review and meta-analysis was performed. Outcomes included death, CRT nonresponse, and changes in left ventricular (LV) remodeling, quality of life (QoL), and 6-minute hall walk distance (6MWD).</AbstractText>Twenty-three observational studies were included and followed a total of 7,495 CRT recipients, 25.5% with AF, for a mean of 33 months. AF was associated with an increased risk of nonresponse to CRT (34.5% vs 26.7%; pooled relative risk [RR] 1.32; 95% confidence interval [CI] 1.12, 1.55; P = .001)) and all-cause mortality (10.8% vs 7.1% per year, pooled RR 1.50, 95% CI 1.08, 2.09; P = .015). The presence of AF was also associated with less improvement in QoL, 6-minute hall walk distance, and LV end-systolic volume but not LV ejection fraction. Among patients with AF, AVN ablation appeared favorable with a lower risk of clinical nonresponse (RR 0.40; 95% CI 0.28, 0.58; P <.001) and a reduced risk of death.</AbstractText>The benefits of CRT appear to be attenuated in patients with AF. The presence of AF is associated with an increased risk of clinical nonresponse and death than in patients without AF. AVN ablation may improve CRT outcomes in patients with AF.</AbstractText>Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,420 | Post-ATHENA and beyond. | Dronedarone, an amiodarone analog, was developed to be a safer alternative to amiodarone. Dronedarone is useful in suppressing atrial fibrillation/flutter and controlling the ventricular response. Dronedarone reduced cardiovascular hospitalization in the ATHENA trial (A placebo-controlled, double-blind, parallel arm Trial to assess the efficacy of dronedarone 400 mg bid for the prevention of cardiovascular Hospitalization or death from any cause in patiENts with Atrial fibrillation/atrial flutter). This paper reviews the results of ATHENA, including subsequent sub-analyses of the trial. These results raise the hypothesis that many of the benefits noted from this trial may be secondary to more than the antiarrhythmic properties of dronedarone. Future studies will clarify the mechanisms of this beneficial effect. |
15,421 | Effect of telmisartan and ramipril on atrial fibrillation recurrence and severity in hypertensive patients with metabolic syndrome and recurrent symptomatic paroxysmal and persistent atrial fibrillation. | This study evaluated the effect of telmisartan, ramipril, and amlodipine on atrial fibrillation (AF) recurrence and severity in hypertensive patients with metabolic syndrome. A total of 391 hypertensive outpatients with metabolic syndrome, in sinus rhythm but with at least 2 episodes of AF in the previous 6 months were randomized to telmisartan, ramipril, or amlodipine for 1 year. At the first AF, ventricular rate (VR) and plasma cardiac troponin I (TnI) were evaluated. P-wave dispersion (PWD) and procollagen type I carboxy-terminal peptide (PIP) were evaluated before and after 12 months of treatment. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were similarly and significantly reduced by all treatments (P < .001). In all, 49% of patients treated with amlodipine had a recurrence of AF as did 25.5% of patients with ramipril and 12.9% of patients with telmisartan (P < .01 vs amlodipine and P < .05 vs ramipril). Ventricular rate and TnI at the first AF recurrence were significantly lower with telmisartan and ramipril than with amlodipine. P-wave dispersion was reduced by ramipril (-5.1 ms, P < .05) and even more by telmisartan (-11 ms, P < .01). Telmisartan and ramipril induced a similar PIP reduction (-52.8 and -49.8 µg/L, respectively, P < .01). These findings suggested that in these patients telmisartan was more effective than ramipril in reducing AF recurrence and severity as well as in improving PWD, despite a similar BP reduction and a similar improvement in cardiac fibrosis. This could be related to a specific effect of telmisartan on atrial electric remodeling. |
15,422 | Eicosapentaenoic acid prevents atrial fibrillation associated with heart failure in a rabbit model. | Atrial fibrillation (AF) is associated with morbidity and mortality of heart failure. Eicosapentaenoic acid (EPA), which is contained in fish oil, was shown to reduce the risk of cardiovascular diseases. We investigated the effects of EPA on AF associated with heart failure in a rabbit model. Rabbits were subjected to ventricular tachypacing (VTP) for 4 wk with or without EPA treatment. Continuous VTP induced heart failure status in these rabbits. The duration of AF (DAF) induced by burst pacing was analyzed by electrophysiological studies. VTP resulted in increased DAF following burst pacing. EPA treatment attenuated increased DAF. Atrial fibrosis increased in response to VTP, accompanied by extracellular signal-regulated kinase (ERK) phosphorylation and transforming growth factor-β1 (TGF-β1) expression in the atrium. Treatment with EPA attenuated atrial fibrosis, ERK phosphorylation, and TGF-β1 expression in response to VTP. EPA treatment increased adiponectin as an anti-inflammatory adipokine and decreased tumor necrosis factor-α as a proinflammatory adipokine in the atrium and epicardial adipose tissues. EPA attenuated VTP-induced AF promotion and atrial remodeling, which was accompanied by modulating the profiles of adipokine production from epicardial adipose tissue. EPA may be useful for prevention and treatment of AF associated with heart failure. |
15,423 | Ventricular arrhythmias and mortality associated with isoflurane and sevoflurane in a porcine model of myocardial infarction. | Ischemia of the myocardium can lead to reversible or irreversible injury depending on the severity and duration of the preceding ischemia. Here we compared sevoflurane and isoflurane with particular reference to their hemodynamic effects and ability to modify the effects of acute severe myocardial ischemia and reperfusion on ventricular arrhythmias and mortality in a porcine model of myocardial infarction. Female Large White pigs were premedicated with ketamine, midazolam, and atropine. Propofol was given intravenously for the anesthetic induction, and anesthesia was maintained with isoflurane or sevoflurane. Endovascular, fluoroscopy-guided, coronary procedures were performed to occlude the midleft anterior descending artery by using a coronary angioplasty balloon. After 75 min, the balloon catheter system was withdrawn and the presence of adequate reperfusion flow was verified. The pigs were followed for 2 mo, and overall mortality rate was calculated. The isoflurane group showed lower arterial pressure throughout the procedure, with the difference reaching statistical significance after induction of myocardial ischemia. The ventricular fibrillation rate was higher in isoflurane group (81.3%) than the sevoflurane group (51.7%; relative risk, 1.57 [1.03 to 2.4]). Overall survival was lower in the isoflurane group (75%) than the sevoflurane group (96.4%). In conclusion, in this porcine model of myocardial ischemia and reperfusion, sevoflurane was associated with higher hemodynamic stability and fewer ventricular arrhythmias and mortality than was isoflurane. |
15,424 | Indications and outcome of implantable cardioverter-defibrillators for primary and secondary prophylaxis in patients with noncompaction cardiomyopathy. | Noncompaction cardiomyopathy (NCCM) is a rare, primary cardiomyopathy, with initial presentation of heart failure, emboli, or arrhythmias, including sudden cardiac death. Implantable cardioverter-defibrillators (ICDs) are frequently used for primary and secondary prevention in different cardiomyopathy patients, but data about ICD in NCCM are scarce. The aim of this study was, therefore, to investigate ICD indications and outcomes in NCCM patients.</AbstractText>We collected prospective data from our NCCM cohort (n = 77 pts, mean age: 40 ± 14 years). ICD was implanted in 44 (57%) patients with NCCM according to the current ICD guidelines for nonischemic cardiomyopathies: in 12 for secondary prevention (7 × ventricular fibrillation, 5 × sustained ventricular tachycardia [VT]) and in 32 patients for primary prevention (heart failure/severe LV dysfunction). During a mean follow-up of 33 ± 24 months, 8 patients presented with appropriate ICD shocks due to sustained VT after median 6.1 [1-16] months. This included 4 of 32 (13%) patients in the primary prevention group and 4 of 12 (33%) in the secondary prevention group (P = 0.04). 9 patients presented with inappropriate ICD therapy: 6 (19%) in the primary and 3 (25%) in the secondary prevention group, at a median follow-up of 4 (2-23) months.</AbstractText>In our cohort of NCCM patients, an ICD was frequently implanted for primary or secondary prevention of sudden cardiac death. At follow-up, frequent appropriate ICD therapy was observed in both groups, supporting the application of current ICD guidelines for primary and secondary prevention of sudden cardiac death in NCCM.</AbstractText>© 2011 Wiley Periodicals, Inc.</CopyrightInformation> |
15,425 | Catheter ablation of ventricular arrhythmias arising from the right ventricular septum close to the His bundle: features of the local electrogram at the optimal ablation site. | The characteristics of the local electrogram at the optimal ablation site of ventricular arrhythmias (VAs) originating from the right ventricle close to the His bundle (HB) region have rarely been described.</AbstractText>Among 190 consecutive patients with idiopathic VAs with left bundle branch block morphology and inferior-axis deviation, 16 were found to have successful ablation site in the right ventricle close to the HB region (para-Hisian group). The electrophysiologic data were compared between the patients in the para-Hisian group and those with VAs arising from the right ventricular (RV) outflow tract (RVOT group). The distal bipolar electrogram at the successful ablation sites in the para-Hisian group exhibited a significantly greater R-wave duration, lower R-wave amplitude, and slower upright deflection of the initial R wave than did those in the RVOT group (all P < 0.001). In the para-Hisian group, a total of 56 radiofrequency (RF) energy applications were delivered, of which the local electrograms at 16 successful and 40 unsuccessful ablation sites were reviewed. High-frequency R-wave potentials of the bipolar electrogram were present in 14 (88%) of the successful ablation sites. An R-wave duration of greater than 34 ms had a discriminatory power for indicating the site of a successful ablation (area under the receiver-operator characteristics curve 0.90, sensitivity 94%, specificity 80%).</AbstractText>The successful ablation site of the para-Hisian VAs had distinctive local electrogram characteristics. A longer R-wave duration of the bipolar electrogram with high-frequency potentials could be a novel predictor of a successful ablation.</AbstractText>© 2011 Wiley Periodicals, Inc.</CopyrightInformation> |
15,426 | Markers of progenitor cell recruitment and differentiation rise early during ischemia and continue during resuscitation in a porcine acute ischemia model. | Clinical administration of bone marrow-derived stem cells in the setting of acute myocardial infarction (AMI) leads to improved left ventricular ejection fraction. Thymosin beta-4 (TB4) and vascular endothelial growth factor (VEGF) are linked to adult epicardial progenitor cell mobilization and neovascularization and is cardioprotective after myocardial ischemia. This study investigated the time course of TB4 and VEGF during AMI, cardiac arrest, and resuscitation. Fifteen anesthetized and instrumented domestic swine underwent balloon occlusion of the proximal left anterior descending coronary artery. During occlusion, venous blood samples were collected from the right atrium at 5-min intervals until 15 min after the onset of cardiopulmonary resuscitation (CPR). Plasma levels of TB4, VEGF, and matrix metalloproteinase-9 (MMP-9, selected as a marker for remodeling and repair) were measured by ELISA. Generalized linear mixed models were employed to model the time-dependent change in plasma concentration. All variables were natural log transformed, except TB4 values, to normalize distributions. Fifteen animals successfully underwent balloon occlusion of the left anterior descending coronary artery and samples were collected from these subjects. The average onset of spontaneous ventricular fibrillation was 28 min. TB4, VEGF, and MMP-9 demonstrated a statistically significant, time-dependent increase in concentration during ischemia. Following arrest and throughout the first 15 min of resuscitation, MMP-9 had an unchanged rate of rise when compared with the prearrest, ischemic period, with VEGF showing a deceleration in its time-dependent concentration trajectory and TB4 demonstrating an acceleration. Endogenous TB4 and VEGF increase shortly after the onset of AMI and increase through cardiac arrest and resuscitation in parallel to remodeling proteases. These markers continue to rise during successful resuscitation and may represent an endogenous mechanism to recruit undifferentiated stem cells to areas of myocardial injury. |
15,427 | The effects of radiofrequency ablation on left atrial systolic function in patients with atrioventricular nodal reentrant and atrioventricular reentrant tachycardias. | Recurrent supraventricular arrhythmias may cause remodelling of the atria. The effects of radiofrequency (RF) ablation of these arrhythmias on left atrial function have not been well established.</AbstractText>To evaluate the effects of RF ablation on left atrial systolic function in patients with atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular tachycardia (AVRT).</AbstractText>The study group consisted of 70 patients (22 men), in whom successful RF ablation of slow pathway (35 patients) or accessory pathway (35 patients) was performed. Patients with atrial fibrillation, structural heart disease, ventricular arrhythmias (> class 3 Lown), impaired left ventricular systolic function or on antiarrhythmics were excluded. All the patients had echocardiographic study before and 6 months after ablation. Left atrial systolic function was assessed using atrial ejection force (AEF) according to Manning's formula (AEF = 0.5 x ρ x MA x A(2), r: blood density = 1.06 g/cm(3), MA: mitral orifice area [cm(2)], A: A wave velocity). The following left atrial dimensions were assessed: antero-posterior (LA-AP), infero-superior (LA-IS, long axis), medio-lateral (LA-ML, short axis). The correlations between AEF and electrophysiological parameters were analysed (VA - ventriculo-atrial conduction, VA/CL - tachycardia cycle length).</AbstractText>The AEF increased significantly in the AVNRT group (7.78 vs 10.75 kdynes; p < 0.001) whereas it did not change in the AVRT group (8.96 vs 9.50, NS). Left atrial dimensions decreased significantly in both groups (AVNRT group: LA-AP: 38 vs 34 mm; LA-ML: 37 vs 33 mm; LA-IS: 51 vs 45 mm; p < 0.001; AVRT group: LA-AP: 38 vs 36 mm; p < 0.01; LA-ML: 37 vs 35 mm, p < 0.001; LA-IS: 50 vs 46 mm; p < 0.001). There was a significant correlation between the increment of AEF and electrophysiological parameters of the tachycardia (VA, r = -0.51 and VA/CL, r = -0.53).</AbstractText>1. RF ablation of AVNRT is associated with the improvement of left atrial systolic function. 2. Left atrial size decreases following RF ablation of both AVNRT and AVRT. 3. The effects of RF ablation on the left atrial systolic function depends on electrophysiological parameters of the tachycardia (VA and VA/CL).</AbstractText> |
15,428 | Long-term results of the maze procedure on left ventricular function for persistent atrial fibrillation associated with mitral valve disease. | Although the maze procedure is often performed as a surgical treatment for atrial fibrillation (AF) combined with mitral valve surgery, the long-term efficacy of the maze procedure concerning cardiac function has not been determined. The aim of this study was to assess long-term results of the maze procedure for left ventricular function in patients with persistent AF associated with mitral valve disease. We analyzed 38 patients who underwent the maze procedure for persistent AF and mitral valve surgery. The cardiothoracic ratio on chest X-ray and the left atrial dimension, left ventricular end-diastolic dimension, left ventricular end-systolic dimension and left ventricular ejection fraction on transthoracic echocardiography were evaluated before and 6 years after the maze procedure. Twenty-two patients maintained sinus rhythm (SR group) and 16 patients had recurrence of permanent AF (AF group) after the maze procedure. Preoperative cardiac function and the methods of mitral surgery were similar between the two groups. At the latest follow-up, left ventricular function tended to be better in the SR group than in the AF group. Cardiovascular events occurred more often in the AF group during follow-up (50 vs. 18%, p < 0.05). This retrospective study revealed that maintaining the sinus rhythm after the maze procedure for patients who underwent mitral valve surgery might be important for preserving better long-term left ventricular function and result in fewer cardiovascular events. |
15,429 | Neuroprotective effects of 17β-estradiol after hypovolemic cardiac arrest in immature piglets: the role of nitric oxide and peroxidation. | We recently reported that cerebral and cardiac injuries are mitigated in immature female piglets after severe hemorrhage with subsequent cardiac arrest. Female sex was also associated with a smaller increase in the cerebral expression of inducible nitric oxide synthase (iNOS) and neuronal nitric oxide synthase (nNOS). In the current study, we tested the hypothesis that exogenously administered 17β-estradiol (E₂) can improve neurological outcome by NOS modulation. Thirty-nine sexually immature piglets were bled to a mean arterial pressure of 35 mmHg over 15 min. Fifty micrograms per kilogram of E₂ was then administered to 10 male and 10 female animals (estradiol group), whereas control animals (n = 10 males and 9 females) received equal volume of normal saline. The animals were then subjected to ventricular fibrillation (4 min) followed by up to 15 min of open-chest cardiopulmonary resuscitation. Vasopressin 0.4 U · kg⁻¹ and amiodarone 0.5 mg · kg⁻¹ were given, and 3 mL · kg⁻¹ of 7.5% saline with 6% dextran was administered over 20 min. All surviving animals were killed after 3 h, and their brains examined for histological injury and NOS expression. No significant differences were observed in survival or hemodynamics between the groups. Compared with the control group, animals in the E₂ group exhibited a significantly smaller increase in nNOS and iNOS expression, a smaller blood-brain-barrier disruption, and a mitigated neuronal injury. There was a significant correlation between nNOS and iNOS levels and neuronal injury. Interestingly, estradiol attenuated cerebral damage (including lower activation of nNOS and iNOS) both in male and female piglets. In conclusion, in our immature piglet model of hypovolemic cardiac arrest, E₂ downregulates iNOS and nNOS expression and results in decreased blood-brain-barrier permeability disruption and smaller neuronal injury. |
15,430 | Prognostic importance of natriuretic peptides and atrial fibrillation in patients receiving cardiac resynchronization therapy. | The aim of this study was to investigate the prognostic value of natriuretic peptides and atrial fibrillation (AF) on response to cardiac resynchronization therapy (CRT) and mortality.</AbstractText>This study included 338 consecutive CRT patients. Response to CRT was defined as a reduction in left ventricular end-systolic volume of ≥15% in the absence of death at 6-month follow-up. During follow-up (27 ± 19 months), 139 patients (41%) had AF, being new onset in 40 patients (21%). Forty-two patients (12%) had permanent AF. Response to CRT was observed in 168 of 302 patients (56%): 60 of 123 patients (43%) with AF vs. 108 of 179 patients (60%) without AF (P = 0.047). Low baseline atrial natriuretic peptide (ANP) [odds ratio for log(2) ANP 0.49, 95% confidence interval (CI) 0.35-0.68, P < 0.001] and large left ventricular end-systolic volume (odds ratio for every 50 mL 1.40, 95% CI 1.09-1.79, P = 0.009) were independent predictors of response. Neither the presence of AF nor the increase in AF burden independently predicted response. Ninety patients (27%) died; 50 patients (36%) with AF vs. 40 patients (20%) without AF (log rank P = 0.029). Important predictors of all-cause mortality were new-onset AF (hazard ratio 8.11, 95% CI 3.31-19.85, P < 0.001), permanent AF (hazard ratio 3.19, 95% CI 1.61-6.30, P = 0.001), and baseline N-terminal pro-B-type natriuretic peptide (NT-proBNP) (hazard ratio for log(2) NT-proBNP 0.77, 95% CI 0.66-0.90, P = 0.001).</AbstractText>In patients treated with CRT, lower ANP and larger left ventricular end-systolic volume were independent predictors of response. New-onset AF, permanent AF, and NT-proBNP were independently associated with increased all-cause mortality.</AbstractText> |
15,431 | Canadian Cardiovascular Society atrial fibrillation guidelines 2010: rate and rhythm management. | The goals of atrial fibrillation (AF) and atrial flutter (AFL) arrhythmia management are to alleviate patient symptoms, improve patient quality of life, and minimize the morbidity associated with AF and AFL. Arrhythmia management usually commences with drugs to slow the ventricular rate. The addition of class I or class III antiarrhythmic drugs for restoration or maintenance of sinus rhythm is largely determined by patient symptoms and preferences. For rate control, treatment of persistent or permanent AF and AFL should aim for a resting heart rate of <100 beats per minute. Beta-blockers or nondihydropyridine calcium channel blockers are the initial therapy for rate control of AF and AFL in most patients without a history of myocardial infarction or left ventricular dysfunction. Digoxin is not recommended as monotherapy for rate control in active patients. Digoxin and dronedarone may be used in combination with other agents to optimize rate control. The first-choice antiarrhythmic drug for maintenance of sinus rhythm in patients with non structural heart disease can be any one of dronedarone, flecainide, propafenone, or sotalol. In patients with abnormal ventricular function but left ventricular ejection fraction >35%, dronedarone, sotalol, or amiodarone is recommended. In patients with left ventricular ejection fraction <35%, amiodarone is the only drug usually recommended. Intermittent antiarrhythmic drug therapy ("pill in the pocket") may be considered in symptomatic patients with infrequent, longer-lasting episodes of AF or AFL as an alternative to daily antiarrhythmic therapy. Referral for ablation of AF may be considered for patients who remain symptomatic after adequate trials of antiarrhythmic drug therapy and in whom a rhythm control strategy remains desired. |
15,432 | From guidelines to bench: implications of unresolved clinical issues for basic investigations of atrial fibrillation mechanisms. | The 2011 Canadian Cardiovascular Society Atrial Fibrillation (AF) Guidelines provide detailed recommendations for AF management, as well as extensive background information. The Guidelines documents highlight many important unresolved questions and areas of clinical need that could benefit from basic research investigations. This article discusses basic research priorities emanating from the Guidelines reflections. Topics addressed include forms of AF and their interrelations, limitations of the presently available experimental models of AF, genetic factors, determinants of drug efficacy for pharmacologic cardioversion, mechanisms of AF-related thromboembolism, ventricular rate control, drugs for rhythm control, upstream therapy, mechanisms by which catheter ablation controls AF, mechanisms of postoperative AF, and the possibility of novel patient-based surgical procedures. A guidelines-to-bench approach to research may allow for the development of important, clinically relevant new knowledge with impacts on patient management and future AF guidelines. |
15,433 | Comparing the 2010 North American and European atrial fibrillation guidelines. | This article compares the important differences in the American College of Cardiology Foundation (ACCF)/American Heart Association (AHA)/Heart Rhythm Society (HRS), Canadian Cardiovascular Society (CCS), and European Society of Cardiology (ESC) 2010 guidelines on atrial fibrillation (AF). All guidelines recommend more lenient targets for ventricular rate control although the CCS guidelines recommend a target heart rate at rest <100 bpm whereas the the ACCF/AHA/HRS and ESC guidelines accept a target heart rate at rest <110 bpm with provisos. All the guidelines recommend that the choice of antiarrhythmic drug for maintenance of sinus rhythm be based on the underlying cardiovascular disease state. However, the CCS guidelines do not recommend that the use of Class IC drugs or sotalol be restricted in the presence of left ventricular hypertrophy alone. All the guidelines have incorporated dronedarone into their recommendations of antiarrhythmic drug therapy for maintenance of sinus rhythm. However, the CCS guidelines do not make a specific recommendation that the use of dronedarone is reasonable to decrease the risk of hospitalization for cardiovascular causes in patients with AF. The ACCF/AHA/HRS update makes a strong recommendation for catheter ablation in patients with paroxysmal AF who have failed a single anti-arrhythmic drug whereas the CCS and ESC guidelines make this a conditional recommendation. The CCS guidelines are the only guidelines at present that recommend dabigitran for prevention of stroke in high risk patients and suggest that dabigatran is preferred to warfarin for stroke prevention in most patient groups. |
15,434 | Incidence and predictors of asymptomatic atrial fibrillation in patients older than 70 years with complete atrioventricular block and dual chamber pacemaker implantation. | To evaluate predictors of asymptomatic atrial fibrillation in patients older than 70 years with complete atrioventricular (AV) block, normal left ventricular systolic function, and implanted dual chamber (DDD) pacemaker.</AbstractText>Hundred and eighty six patients with complete AV block were admitted over one year to the Sisters of Mercy University Hospital. The study recruited patients older than 70 years, with no history of atrial fibrillation, heart failure, or reduced left ventricular systolic function. All the patients were implanted with the same pacemaker. Out of 103 patients who were eligible for the study, 81 (78%) were evaluated. Among those 81 (78%) were evaluated. Eighty one (78%) patients were evaluated. Follow-up time ranged from 12 to 33 months (average ±standard deviation 23 ± 5 months). Primary end-point was asymptomatic atrial fibrillation occurrence recorded by the pacemaker. Atrial fibrillation occurrence was defined as atrial high rate episodes (AHRE) lasting >5 minutes. Binary logistic regression was used to identify the predictors of development of asymptomatic atrial fibrillation. Results. The 81 patients were stratified into two groups depending on the presence of AHRE lasting >5 minutes (group 1 had AHRE>5 minutes and group 2 AHRE<5 minutes). AHRE lasting >5 minutes were detected in 49 (60%) patients after 3 months and in 53 (65%) patients after 18 moths. After 3 months, only hypertension (odds ratio [OR], 17.63; P = 0.020) was identified as a predictor of asymptomatic atrial fibrillation. After 18 months, hypertension (OR, 14.0; P = 0.036), P wave duration >100 ms in 12 lead ECG (OR, 16.5; P = 0.001), and intracardial atrial electrogram signal amplitude >4 mV (OR, 4.27; P = 0.045) were identified as predictors of atrial fibrillation.</AbstractText>In our study population, hypertension was the most robust and constant predictor of asymptomatic atrial fibrillation after 3 months, while P wave duration >100 ms in 12-lead ECG and intracardial atrial signal amplitude were predictors after 18 months.</AbstractText> |
15,435 | High prevalence of right ventricular dysfunction in ICD patients with shocks: a potential new predictor in risk stratification. | Despite identifying several risk factors for sudden cardiac death, our ability to predict arrhythmic events in patients with an implantable cardioverter defibrillator (ICD) remains poor. The purpose of this study was to determine if patients who received appropriate ICD shocks had a higher degree of right ventricular (RV) dysfunction at baseline when compared to patients who did not receive ICD shocks.</AbstractText>We conducted a 1:2 case-control, retrospective study comparing RV end-diastolic and end-systolic areas (RV ED and RV ES areas, respectively), fractional RV area change, and RV wall thickness in 19 consecutive patients who received appropriate ICD shocks (shock group) with another group of 38 patients who did not receive ICD shocks (no-shock group).</AbstractText>There was no significant difference in the RV end-diastolic areas between the groups. However, patients who experienced ICD shocks had a higher RV end-systolic area and a lower RV fractional area change when compared to patients without ICD shocks, 16.3 ± 4.9 cm(2) and 27.7 ± 9.0% in the shock group versus 14.2 ± 4.4 cm(2) and 35.8 ± 10.3% in the no-shock group; (p = 0.08 and 0.004, respectively). Furthermore, the RV wall thickness was greater in patients with ICD shocks when compared to patients without ICD shocks, 0.49 ± 0.05 cm and 0.44 ± 0.04 cm, respectively (p = 0.001). Utilizing a logistic regression analysis and after controlling for variables with univariate significance (p < 0.1), RV wall thickness independently predicted ICD shocks (OR 13.9 mm(-1) change of RV thickness, p = 0.004).</AbstractText>Our findings suggest that some measurements of RV function might prove to be useful in predicting future arrhythmic events. Additional prospective studies are needed to test this hypothesis.</AbstractText> |
15,436 | The incidence and risk factors for new onset atrial fibrillation in the PROSPER study. | Atrial fibrillation/flutter (AF) is the most common arrhythmia in older people. It associates with reduced exercise capacity, increased risk of stroke, and mortality. We aimed to determine retrospectively whether pravastatin reduces the incidence of AF and whether any electrocardiographic measures or clinical conditions might be risk factors for its development.</AbstractText>The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) was a randomized, double-blind controlled trial that recruited 5804 individuals aged 70-82 years with a history of, or risk factors for, vascular disease. A total of 2891 were allocated to pravastatin and 2913 to placebo; mean follow-up was 3.2 years. Electrocardiograms (ECGs), which were recorded at baseline, annually thereafter, and at run-out, were processed by computer and reviewed manually. In all, 264 of 2912 (9.1%) of the placebo group and 283 of 2888 (9.8%) of the pravastatin-treated group developed AF [hazard ratio 1.08 (0.92,1.28), P= 0.35)]. Multivariate analysis showed that PR and QTc intervals, age, left ventricular hypertrophy, and ST-T abnormalities were related to development of AF after adjustment for many variables including alcohol consumption, which itself was univariately predictive of developing AF. Previous myocardial infarction on the ECG was not a risk factor. A history of vascular disease was strongly linked with developing AF but not diabetes and hypertension.</AbstractText>Pravastatin does not reduce the incidence of AF in older people at risk of vascular disease, at least in the short-medium term. Risk factors for AF include older age, prolongation of PR or QTc intervals, left ventricular hypertrophy, and ST-T abnormalities on the ECG.</AbstractText> |
15,437 | An accessory bypass tract masked by the presence of atrial fibrillation in a horse. | Accessory bypass tracts are rarely documented in horses. Here, we present a case of an accessory bypass tract which was initially masked by the presence of atrial fibrillation. Evidence of ventricular pre-excitation was recognized after cardioversion to normal sinus rhythm and the horse was diagnosed with Wolff-Parkinson-White Syndrome. In people, atrial fibrillation in the presence of an accessory bypass tract is considered dangerous due to the risk of sudden cardiac death. Although we did not consider this horse safe to ride, he continues to compete successfully and has not had recurrence of clinically significant tachyarrhythmias. |
15,438 | Treatment of atrial fibrillation with a dual defibrillator in heart failure patients (TRADE HF): protocol for a randomized clinical trial. | Heart failure(HF) and atrial fibrillation(AF) frequently coexist in the same patient and are associated with increased mortality and frequent hospitalizations. As the concomitance of AF and HF is often associated with a poor prognosis, the prompt treatment of AF in HF patients may significantly improve outcome.</AbstractText><AbstractText Label="METHODS/DESIGN" NlmCategory="METHODS">Recent implantable cardiac resynchronization (CRT) devices allow electrical therapies to treat AF automatically. TRADE-HF (trial registration: NCT00345592; http://www.clinicaltrials.gov) is a prospective, randomized, double arm study aimed at demonstrating the efficacy of an automatic, device-based therapy for treatment of atrial tachycardia and fibrillation(AT/AF) in patients indicated for CRT. The study compares automatic electrical therapy to a traditional more usual treatment of AT/AF: the goal is to demonstrate a reduction in a combined endpoint of unplanned hospitalizations for cardiac reasons, death from cardiovascular causes or permanent AF when using automatic atrial therapy as compared to the traditional approach involving hospitalization for symptoms and in-hospital treatment of AT/AF.</AbstractText>CRT pacemaker with the additional ability to convert AF as well as ventricular arrhythmias may play a simultaneous role in rhythm control and HF treatment. The value of the systematic implantation of CRT ICDs with the capacity to deliver atrial therapy in HF patients at risk of AF has not yet been explored. The TRADE-HF study will assess in CRT patients whether a strategy based on automatic management of atrial arrhythmias might be a valuable option to reduce the number of hospital admission and to reduce the progression the arrhythmia to a permanent form.</AbstractText>NCT00345592.</AbstractText> |
15,439 | Temperature-controlled cooled-tip radiofrequency linear ablation of the atria guided by a realtime position management system. | Due to the difficulty in producing a transmural linear lesion and the possibility of complications such as thrombus formation leading to thromboembolism, the catheter-based maze procedure remains problematic. We tested, in pigs, the possibility of using a temperature-controlled cooled-tip radiofrequency (RF) ablation system together with a realtime position management (RPM) system to create a transmural linear lesion uncomplicated by thrombus formation.Nine pigs underwent insertion of two electrode catheters (each with two ultrasound electrodes), one into the coronary sinus (CS) and one into the right ventricular apex (references for ultrasound-based non-fluoroscopic three-dimensional mapping). A cooled-tip catheter (with two ultrasound electrodes) was introduced into the right atrium. Linear right atrial ablation was performed with a custom radiofrequency (RF) generator. The catheter was perfused with 0.66 mL/second of saline. RF was delivered for 60 seconds at a target temperature of 40°C. A linear ablation line was created between the superior vena cava and inferior vena cava. Three-dimensional isochronal maps were created during CS pacing before and after ablation. In 4 of the 9 pigs, a transmural linear ablation line was confirmed by three-dimensional mapping and postmortem macroscopic examination. No endocardial thrombus formation was noted. Temperature-controlled cooled-tip RF linear ablation guided by an RPM system appears to have potential for creating linear lesions in the atria. Further studies are needed to determine whether such an ablation technique and the parameters used will facilitate successful completion of the catheter-based maze procedure. |
15,440 | Clinical profiles, efficacy of antiarrhythmic drug therapy, and cardiovascular prognosis in patients with first detected paroxysmal atrial fibrillation. | Little information is available concerning clinical profiles and outcomes of treatment in Japanese patients with first detected atrial fibrillation (AF). In the present study, 459 patients with paroxysmal AF (309 males, mean age, 66 ± 12 years) were divided into a first detected AF group (group A, n = 143) and a non-first detected AF group (group B, n = 316). Clinical profiles, prophylactic efficacy of antiarrhythmic drug therapy (AAD), and cardiovascular prognosis during a mean follow-up period of 50 ± 35 months were compared between the two groups. The number of AF recurrences in the individual patients regardless of AAD were significantly lower in group A than in group B (0.8 ± 1.4 versus 1.7 ± 1.9)(P < 0.05). The percentages of patients free from conversion to chronic AF at 12, 36, 60, and 120 months were significantly higher in group A (98%, 96%, 93%, and 91%, respectively) than in group B (95%, 86%, 83%, and 79%, respectively)(P < 0.01). The annual rates of hospitalization for thromboembolism, heart failure, and cardiovascular death did not differ between group A (2.2%, 1.1% and 1.0%, respectively) and group B (2.2%, 1.9% and 1.1%, respectively). In multivariate logistic regression analysis, a CHADS₂ score ≥ 2 points (odds ratio 13.1, 95% confidence interval 3.36-51.0, P = 0.001), nocturnal AF onset (OR 0.201, 95% CI 0.050-0.815, P = 0.025), left ventricular diastolic dimension (LVDd) ≥ 50 mm (OR 3.845, 95% CI 1.078-13.71, P = 0.038), and conversion to chronic AF (OR 3.547, 95% CI 1.002-13.64, P = 0.048) were associated with cardiovascular events in group A. Rhythm control therapy with antiarrhythmic drugs was shown to be more effective for patients in group A than in group B. It is particularly important to prevent cardiovascular events in first detected AF patients with a CHADS₂ score ≥ 2 points, LVDd ≥ 50 mm, and conversion to chronic AF. |
15,441 | Is hypothermia after cardiac arrest effective in both shockable and nonshockable patients?: insights from a large registry. | Although the level of evidence of improvement is significant in cardiac arrest patients resuscitated from a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia [VF/Vt]), the use of therapeutic mild hypothermia (TMH) is more controversial in nonshockable patients (pulseless electric activity or asystole [PEA/asystole]). We therefore assessed the prognostic value of hypothermia for neurological outcome at hospital discharge according to first-recorded cardiac rhythm in a large cohort.</AbstractText>Between January 2000 and December 2009, data from 1145 consecutive out-of-hospital cardiac arrest patients in whom a successful resuscitation had been achieved were prospectively collected. The association of TMH with a good neurological outcome at hospital discharge (cerebral performance categories level 1 or 2) was quantified by logistic regression analysis. TMH was induced in 457/708 patients (65%) in VF/Vt and in 261/437 patients (60%) in PEA/asystole. Overall, 342/1145 patients (30%) reached a favorable outcome (cerebral performance categories level 1 or 2) at hospital discharge, respectively 274/708 (39%) in VF/Vt and 68/437 (16%) in PEA/asystole (P<0.001). After adjustment, in VF/Vt patients, TMH was associated with increased odds of good neurological outcome (adjusted odds ratio, 1.90; 95% confidence interval, 1.18 to 3.06) whereas in PEA/asystole patients, TMH was not significantly associated with good neurological outcome (adjusted odds ratio, 0.71; 95% confidence interval, 0.37 to 1.36).</AbstractText>In this large cohort of cardiac arrest patients, hypothermia was independently associated with an improved outcome at hospital discharge in patients presenting with VF/Vt. By contrast, TMH was not associated with good outcome in nonshockable patients. Further investigations are needed to clarify this lack of efficiency in PEA/asystole.</AbstractText> |
15,442 | Ventricular fibrillation as a likely consequence of capecitabine-induced coronary vasospasm. | Capecitabine is a member of the fluoropyrimidine family of chemotherapeutic agents that selectively delivers 5-fluorouracil (5-FU) to tumors. It is increasingly used as part of combined modality treatment for gastrointestinal malignancies. Cardiotoxicity has been documented to occur with 5-FU, but due to an expansion in capecitabine use, reports exist of its propensity to coronary vasospasm. We report the case of a 28-year-old man, with no preceding angina, presenting with a reversible episode of ventricular fibrillation (VF) at rest in his fifth course of capecitabine chemotherapy for metastatic colorectal cancer. Emergency resuscitation successfully restored spontaneous circulation, with initial ST segment elevation in the inferolateral leads on electrocardiogram prompting emergency coronary angiography. This demonstrated normal coronary arteries. ST segments normalized post-angiography and the patient rapidly recovered with no myocardial damage sustained. An implantable cardioverter-defibrillator was placed for secondary prevention of sudden death, and capecitabine was implicated as the cause of coronary vasospasm which resulted in his presentation of VF. To our knowledge, this is the first episode of VF as a consequence of suspected capecitabine-induced coronary vasospasm occurring at rest. Our case highlights the potential for severe cardiotoxic consequences of capecitabine including sudden death from VF, and given the multi-disciplinary approach to managing oncology patients, health professionals should be aware of this. |
15,443 | Meta-analysis: cardiac resynchronization therapy for patients with less symptomatic heart failure. | Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with advanced symptoms of heart failure.</AbstractText>To assess the benefits and harms of CRT in patients with advanced heart failure and those with less symptomatic disease.</AbstractText>A search of electronic databases (1950 to December 2010), hand-searching of reference lists, and unpublished data from principal investigators. Searches were not limited to the English language.</AbstractText>Randomized, controlled trials of CRT compared with usual care and right or left ventricular pacing in adults with heart failure and a left ventricular ejection fraction of 0.40 or less.</AbstractText>Two reviewers performed independent study selection, data abstraction, and quality assessment by using the Cochrane tool for assessing risk for bias.</AbstractText>There were 9082 patients in 25 trials. In patients with New York Heart Association (NYHA) class I and II symptoms, CRT reduced all-cause mortality (6 trials, 4572 participants; risk ratio [RR], 0.83 [95% CI, 0.72 to 0.96]) and heart failure hospitalizations (4 trials, 4349 participants; RR, 0.71 [CI, 0.57 to 0.87]) without improving functional outcomes or quality of life. In patients with NYHA class III or IV symptoms, CRT improved functional outcomes and reduced both all-cause mortality (19 trials, 4510 participants; RR, 0.78 [CI, 0.67 to 0.91]) and heart failure hospitalizations (11 trials, 2663 participants; RR, 0.65 [CI, 0.50 to 0.86]). The implant success rate was 94.4%; peri-implantation deaths occurred in 0.3% of trial participants, mechanical complications in 3.2%, lead problems in 6.2%, and infections in 1.4%.</AbstractText>Subgroup analyses were underpowered and lack data for persons with NYHA class I symptoms, atrial fibrillation, chronic kidney disease, or right bundle branch block.</AbstractText>Cardiac resynchronization therapy is beneficial for patients with reduced left ventricular ejection fraction, symptoms of heart failure, and prolonged QRS, regardless of NYHA class.</AbstractText>None.</AbstractText> |
15,444 | Toward prediction of the local onset of alternans in the heart. | A beat-to-beat variation in the cardiac action potential duration is a phenomenon known as alternans. Alternans has been linked to ventricular fibrillation, and thus the ability to predict the onset of alternans could be clinically beneficial. Theoretically, it has been proposed that the slope of a restitution curve, which relates the duration of the action potential to the preceding diastolic interval, can predict the onset of alternans. Experimentally, however, this hypothesis has not been consistently proven, mainly because of the intrinsic complexity of the dynamics of cardiac tissue. It was recently shown that the restitution portrait, which combines several restitution curves simultaneously, is associated with the onset of alternans in isolated myocytes. Our main purpose in this study was to determine whether the restitution portrait is correlated with the onset of alternans in the heart, where the dynamics include a spatial complexity. We performed optical mapping experiments in isolated Langendorff-perfused rabbit hearts in which alternans was induced by periodic pacing at different frequencies, and identified the local onset of alternans, B(onset). We identified two regions of the heart: the area that exhibited alternans at B(onset) (1:1(alt)) and the area that did not (1:1). We constructed two-dimensional restitution portraits for the epicardial surface of the heart and measured the spatial distribution of three different slopes (the dynamic restitution slope, S(dyn)(RP), and two local S1-S2 slopes, S(12) and S(12)(max)) separately for these two regions. We found that the S(12) and S(12)(max) slopes differed significantly between the 1:1(alt) and 1:1 regions just before the onset of alternans, and S(dyn)(RP) slopes were statistically similar. In addition, we found that the slopes of the dynamic restitution curve S(dyn) were also statistically similar between these two regions. On the other hand, the quantitative values of all slopes were significantly different from the theoretically predicted value of one. These results demonstrate that the slopes measured in the restitution portrait correlate with the onset of alternans in the heart. |
15,445 | Effects of high thoracic epidural anesthesia on atrial electrophysiological characteristics and sympathetic nerve sprouting in a canine model of atrial fibrillation. | High thoracic epidural anesthesia (HTEA) blocks the afferent and efferent cardiac sympathetic nerve fibers and may affect atrial electrophysiological characteristics and nerve sprouting in patients with atrial fibrillation (AF). In this study, 18 dogs were randomly divided into a control group (n = 6), in which dogs were atrially paced at 400 beats/min for 6 weeks; an HTEA group (n = 6), in which dogs underwent atrial pacing and HTEA for 6 weeks; and a sham-operated group (n = 6), in which dogs underwent the operation but did not receive atrial pacing or HTEA. Electrophysiological examinations were performed in all groups. Cardiac nerves were immunocytochemically stained with anti-growth-associated protein 43 (GAP43) and anti-tyrosine hydroxylase (TH) antibodies. The protein expressions of nerve growth factor (NGF), GAP43 and TH in atrial myocardium were also studied by western blot. In addition, the plasma levels of C-reactive protein (CRP) and norepinephrine, as well as atrial production of superoxide anion (O(2)(·-)) and malondialdehyde, were measured. In the HTEA group, atrial effective refractory period increased (P < 0.05) and AF maintenance decreased (P < 0.01) significantly compared with the control group. The densities of GAP43-positive nerves and TH-positive nerves were significantly lower in the HTEA group compared with the control group. The protein levels of NGF, GAP43 and TH were also lower in the HTEA group compared with the control group. A significant positive correlation between the expressions of NGF and GAP43 (P < 0.01) was observed. A similar correlation was demonstrated for NGF and TH (P < 0.01) in our study. Furthermore, the plasma levels of CRP and norepinephrine, as well as the amount of O(2)(·-) and malondialdehyde produced from myocardium, decreased in the HTEA group compared with the control group. In conclusion, HTEA inhibited electrical and nerve remodeling and reduced the maintenance of AF in a canine AF model, in which process HTEA exhibited anti-inflammatory and antioxidant effects, indicating that, in addition to the efferent cardiac sympathetic nerve, afferent fibers also play an important role in the initiation and/or maintenance of AF. |
15,446 | Left ventricular mechanical support with Impella provides more ventricular unloading in heart failure than extracorporeal membrane oxygenation. | The Impella microaxial-flow pump can directly unload left ventricle (LV) in cases of acute heart failure. Extracorporeal membrane oxygenation (ECMO) is widely used for circulatory support. Although the clinical effectiveness of ECMO has been demonstrated, insufficient LV loading reduction may not be advantageous for myocardial recovery. The objective was to compare ventricular loading reduction and reversibility of ventricular fibrillation (VF) with either Impella or ECMO. Six dogs were used. Extracorporeal membrane oxygenation was established by the femoral artery and right atrium. The Impella LD was inserted in LV by the ascending aorta. An acute failing heart was created by sequential coronary artery ligations. Pressure-volume (PV) relationships were acquired without a device and with ECMO or Impella. When VF occurred, direct cardioversion was performed while supported by either ECMO or Impella. The PV area, which is a measure of ventricular unloading and is correlated with myocardial oxygen consumption, decreased more with Impella than with ECMO. Successful defibrillation was achieved more effectively while under Impella support. Superior ventricular unloading with the Impella device may provide higher recovery potential to damaged hearts than ECMO and may have a significant impact not only on intensive care of patients with heart failure but also on resuscitation. |
15,447 | Efficacy of portable and percutaneous cardiopulmonary bypass rewarming versus that of conventional internal rewarming for patients with accidental deep hypothermia. | Since 2001, at our institution, a portable and percutaneous cardiopulmonary bypass system has been used for rewarming of patients with accidental deep hypothermia. Before 2001, a conventional internal rewarming technique was used. The aim of this research is to examine the efficacy of portable and percutaneous cardiopulmonary bypass for rewarming of patients with accidental severe hypothermia and compare it with that of conventional rewarming methods.</AbstractText>Historical study.</AbstractText>The exclusive emergency medical center and trauma center level 1 in Western Kanagawa, Japan.</AbstractText>From April 1992 to March 2009, 70 patients with accidental deep hypothermia (core temperature <28°C) were transferred to our hospital. Two patients presented with intracranial hemorrhage on initial head computed tomography scans. These two patients were excluded because each required an emergency operation. Therefore, 68 patients were included in this study. We compared patients' clinical characteristics and outcomes. The parameters included the following: sex, age, vital signs on arrival to our hospital (Glasgow coma Scale scores, systolic blood pressure, heart rate, respiratory rate, core temperature), electrocardiogram on arrival to our hospital, rewarming speed, time of rewarming until 34°C was reached, ventricular fibrillation occurrence rate during rewarming, cause of cold environmental exposure, Glasgow Outcome Scale scores, and mortality. In addition, we divided the conventional and portable and percutaneous cardiopulmonary bypass rewarming groups into two categories depending on whether cardiopulmonary arrest occurred on arrival to our hospital. We also compared the survival rate and average Glasgow Outcome Scale scores for each group.</AbstractText>None.</AbstractText>Patients' clinical backgrounds did not differ significantly between the conventional and portable and percutaneous cardiopulmonary bypass rewarming groups. Glasgow Outcome Scale scores and survival rates of the portable and percutaneous cardiopulmonary bypass rewarming group patients, irrespective of whether cardiopulmonary arrest was experienced on arrival to our hospital, were significantly higher than those of the conventional rewarming group.</AbstractText>Portable and percutaneous cardiopulmonary bypass rewarming can improve the mortality rates and Glasgow Outcome Scale scores of accidental deep hypothermia patients.</AbstractText> |
15,448 | Continuous T-wave alternans monitoring to predict impending life-threatening cardiac arrhythmias during emergent coronary reperfusion therapy in patients with acute coronary syndrome. | T-wave alternans (TWA) can precede onset of ventricular tachyarrhythmia (VTA). We evaluated the usefulness of continuous TWA monitoring in ultra-short-term prediction of impending life-threatening VTA upon emergent reperfusion in acute coronary syndrome (ACS) patients.</AbstractText>Twenty consecutive ACS patients undergoing emergent reperfusion therapy were studied. Continuous ambulatory electrocardiograms (ECGs) (leads V1 and V5) were recorded during emergency room visit and therapy. Peak TWA was determined before and after reperfusion by the modified moving average method. Coronary balloon angioplasty/stenting was successfully performed in 19 patients and intracoronary vasodilator was administered in 1 patient with coronary spasm. Three (15.0%) patients developed VTA requiring cardioversion soon after reperfusion. Peak TWA before reperfusion was higher in patients with VTA than in those without (33.0 ± 4.4 vs. 15.8 ± 4.0 µV, P < 0.001). Two patients with arrhythmia exhibited an upsurge in TWA to 75 and 105 µV before onset of VTA. In the third patient, macroscopic TWA appeared in leads V1-V4 in a 12-lead ECG prior to VTA upon pharmacological resolution of vasospasm, although the ambulatory ECG field of view could not detect the upsurge.</AbstractText>Acute coronary syndrome patients at risk of developing VTA soon after reperfusion exhibit premonitory episodes of increased TWA. Thus, TWA monitoring may be useful for ultra-short-term prediction of life-threatening cardiac arrhythmia risk upon emergent reperfusion in ACS patients. Continuous 12-lead ECGs may be required to optimize detection of TWA, which is regionally specific.</AbstractText> |
15,449 | Acute effects of ganglionated plexi ablation on sinoatrial nodal and atrioventricular nodal functions. | Ganglionated plexus (GP) ablation has been shown effective for eliminating atrial fibrillation (AF), the most common clinical tachyarrhythmia. However, the safety of destroying the main cardiac autonomic structures remains unclear. This study investigated the acute effects of GP ablation on the sinoatrial nodal (SAN) and atrioventricular nodal (AVN) functions in a canine model. In 10 open-chest dogs, multiple electrode catheters were sutured at both atria for recording and pacing. SAN and AVN function were evaluated. GP ablation caused no significant change of sinus rate immediately after GP ablation compared with the baseline state. After GP ablation, the sinus node recovery time (SNRT) and corrected SNRT did not show significant changes at long pacing cycle lengths (CLs), and only showed significant decrease at shorter pacing CLs. The AH interval at different pacing CLs, the Wenckebach atrioventricular block (AVB) CL, 2:1 AVB CL or the ventricular rate during AF were not significantly altered by GP ablations. Vagal suppression of SAN and AVN functions was eliminated by GP ablation. GP staining showed abundant choline acetyl transferase or tyrosine hydroxylase positive neurons. These findings suggest the functions of the SAN and AVN are mainly retained after GP ablation. These results may be partially related to destroying both parasympathetic and sympathetic elements in the GP by ablation. |
15,450 | Temporal stability of defibrillation thresholds with cardiac resynchronization therapy. | Defibrillation thresholds (DFTs) are typically stable over time among patients with implantable cardioverter-defibrillators (ICDs). However, the impact of cardiac resynchronization therapy (CRT) on DFTs has not been studied systematically.</AbstractText>This study prospectively evaluated the effect of CRT and left ventricular (LV) chamber reverse remodeling on DFTs.</AbstractText>This prospective, multicenter study evaluated 54 cardiac resynchronization therapy defibrillator (CRT-D) patients. Echocardiography and DFTs were performed both at implantation and at 6 months after implantation. All patients received dual-coil leads and a CRT-D pulse generator. DFTs were measured using a binary search method and tuned biphasic waveforms, where the shock pulse widths were determined by the measured shock impedance. Echocardiograms were analyzed by an independent core laboratory with a responder defined as a decrease of left ventricular end systolic volume >15%.</AbstractText>The study cohort was 74% male, with a mean age of 68.7 ± 10.9 years. The baseline ejection fraction was 0.245 ± 0.076, and the mean New York Heart Association class was 2.9 ± 0.4. In CRT responders (n = 32) the mean DFT was 415.6 ± 108.1 V at implantation vs. 415.6 ± 124.7 V at 6 months (P = .9), and in nonresponders (n = 19) the mean DFT was 452.6 ± 102 V at implantation vs. 447.4 ± 112.4 V at 6 months (P = .8). There was no significant change in DFT peak voltage, delivered energy, or shock impedance over time.</AbstractText>DFTs were unchanged at 6 months in CRT patients with or without LV chamber reverse remodeling.</AbstractText>Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,451 | Spontaneous electrocardiogram alterations predict ventricular fibrillation in Brugada syndrome. | Patients with Brugada syndrome (BS) often have spontaneous changes in their electrocardiogram (ECG).</AbstractText>To evaluate the significance of ECG alterations, we investigated the relationships between the ECG and the occurrence of ventricular fibrillation (VF) in both patients and an experimental model of BS.</AbstractText>In study 1, we evaluated ECG alterations in BS patients with (VF+, n = 33) and without (VF-, n = 41) spontaneous VF. We defined type 0 ECG as coved-type ST elevation without a negative T wave, which represents the existence of loss-of-dome (LOD) type action potentials (APs). In study 2, we optically mapped epicardial APs and recorded transmural ECGs in 34 canine right ventricular tissues with a drug-induced BS model by a combination of pinacidil and pilsicainide.</AbstractText>In study 1, changes in ST level ≥0.2 mV were more frequent in the VF+ group than in the VF- group (P <.01). Spontaneous ECG alterations and appearances of types 1 and 0 ECGs were more frequent in the VF+ group than in the VF- group (P <.01). In study 2, BS model with spike-and-dome (SAD) epicardial APs exhibited type 1 ECG. Deepening of the phase 1 notch of the APs induced heterogeneous conversion of the APs (SAD→LOD) and resulted in ECG conversion from type 1 to type 0. Significant AP heterogeneity often appeared during AP alterations and initiated phase 2 reentry. Tissues having ventricular tachycardia (VT; n = 20) had more frequent alterations in APs and ECG than in tissues without VT (n = 14; P <.01).</AbstractText>ECG alterations, especially conversion between types 0 and 1, are associated with significant AP heterogeneity that can initiate VF in BS.</AbstractText>Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,452 | Effects of n-3 polyunsaturated fatty acids on malignant ventricular arrhythmias in patients with chronic heart failure and implantable cardioverter-defibrillators: A substudy of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca (GISSI-HF) trial. | The antiarrhythmic effects of n-3 polyunsaturated fatty acids (n-3PUFA) in ischemic heart disease have been demonstrated; however, studies in patients surviving malignant ventricular arrhythmias of different etiologies treated with an implantable cardioverter-defibrillator (ICD) have given conflicting results. The purpose of this study was to assess the antiarrhythmic effect of n-3PUFA versus placebo in 566 patients with heart failure enrolled in the GISSI-HF trial who received an ICD for secondary or primary prevention of ventricular fibrillation (VF) or tachycardia (VT).</AbstractText>Clinical data and arrhythmic event recordings extracted from the device memory were obtained. We tested the treatment effect by a multivariate Cox model adjusting for all clinical parameters associated with the primary end point defined as time to first appropriate ICD discharge for VT/VF.</AbstractText>In the 566 patients with at least one recorded follow-up visit, 1363 VT and 316 VF episodes were terminated by ICD pacing or shock over a median follow-up of 928 days. The incidence of the primary end point event was 27.3% in the n-3PUFA group and 34.0% in the placebo group (adjusted hazard rate = 0.80, 95% CI 0.59-1.09, P = .152). Patients who received 1, 2 to 3, or >3 ICD discharges were 8.9%, 7.1%, and 11.1% in the n-3PUFA group, compared with slightly higher rates of 11.1%, 10.7%, and 12.1% in the placebo group (overall P = .30). Patients with the highest 3-month increase in plasma n-3PUFA had a somewhat lower incidence of arrhythmic events.</AbstractText>The results of this study, though not statistically significant, support prior evidences of an antiarrhythmic effect of n-3PUFA in patients with ICD, although they leave open the issue of whether this effect leads to a survival benefit.</AbstractText>Copyright © 2011 Mosby, Inc. All rights reserved.</CopyrightInformation> |
15,453 | Male gender and chronic obstructive pulmonary disease predict a poor clinical response in patients undergoing cardiac resynchronisation therapy. | Current guidelines advocate cardiac resynchronisation therapy (CRT) in patients with class III/IV New York Heart Association (NYHA) heart failure, depressed left ventricular function and a broad QRS. However, a significant proportion of patients do not derive any benefit from CRT. The aim of this study was to identify clinical, electrocardiographic and echocardiographic predictors of response to CRT.</AbstractText>A retrospective analysis of patients undergoing CRT in our institution was performed. A favourable clinical response to CRT was defined as an improvement in NYHA Heart failure class of ≥ 1 and lack of hospitalisation with heart failure. Comparisons were made between responders and non-responders in terms of baseline characteristics and potential predictors of CRT response (QRS width, presence of left bundle branch block, atrial fibrillation, evidence of mechanical dyssynchrony on echocardiography and LV lead position).</AbstractText>A total of 164 patients had full follow-up data. The mean follow-up was 293 days. Of patients undergoing CRT, 90 (58.9%) had a favourable clinical response to CRT. Predictors of a lack of clinical response to CRT were male gender (p = 0.012) and chronic obstructive pulmonary disease (COPD) (0.008). Pre-implant echocardiographic dyssynchrony assessment appeared not to predict response to CRT (p = 0.87); however, there was a trend towards a positive response in those patients with significant dyssynchrony (p = 0.09) defined as interventricular delay > 40 ms or maximal LV delay of > 80 ms.</AbstractText>Male gender and coexisting COPD were shown to be independent predictors of non-response to CRT in this cohort of patients fulfilling current criteria for CRT.</AbstractText>© 2011 Blackwell Publishing Ltd.</CopyrightInformation> |
15,454 | Association of left atrial fibrosis detected by delayed-enhancement magnetic resonance imaging and the risk of stroke in patients with atrial fibrillation. | This study tried to determine the association between left atrial (LA) fibrosis, detected using delayed-enhanced magnetic resonance imaging (DE-MRI), and the CHADS(2) score (point system based on individual clinical risk factors including congestive heart failure, hypertension, age, diabetes, and prior stroke) variables, specifically stroke.</AbstractText>In patients with atrial fibrillation (AF), conventional markers for the risk of stroke base their higher predictive effect on clinical features, particularly previous stroke history, and not individual LA pathophysiological properties. We aimed to determine the association between LA fibrosis, detected using DE-MRI, and the CHADS(2) score variables, specifically stroke.</AbstractText>Patients with AF who presented to the AF clinic and received a DE-MRI of the LA were evaluated. Their risk factor profiles, including a CHADS(2) score, were catalogued. The degree of LA fibrosis was determined as a percentage of the LA area. Any history of previous strokes, warfarin use, or cerebrovascular disease was recorded.</AbstractText>A total of 387 patients, having a mean age of 65 ± 12 years, 36.8% female, were included in this study. A history of previous stroke was present in 36 (9.3%) patients. Those patients with previous strokes had a significantly higher percentage of LA fibrosis (24.4 ± 12.4% vs. 16.2 ± 9.9%, p < 0.01). A larger amount of LA fibrosis was also seen in those patients with a higher CHADS(2) score (≥ 2: 18.7 ± 11.4 vs. <2: 14.7 ± 9.2, p < 0.01). A logistic regression analysis of all variables except strokes (CHAD score) demonstrated that LA fibrosis independently predicted cerebrovascular events (p = 0.002) and significantly increased the predictive performance of the score (area under the curve = 0.77).</AbstractText>Our preliminary, multicenter results suggest DE-MRI-based detection of LA fibrosis is independently associated with prior history of strokes. We propose that the amount of DE-MRI-determined LA fibrosis could represent a marker for stroke and a possible therapeutic target with potential applicability for clinical treatment for patients with AF.</AbstractText>Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,455 | Use of intracardiac echocardiography in the electrophysiology laboratory. | The intracardiac echocardiography (ICE) offers a detailed visualization of the cardiac structures, in association with hemodynamic information, allowing the precise and real-time positioning of the catheters, decreasing the time of exposure to fluoroscopy and the monitoring of acute complications during the electrophysiological procedure (i.e., formation of thrombi, pericardial effusion, cardiac tamponade), Consequently, its use has progressively increased, mainly in the ablation of atrial fibrillation and ventricular arrhythmias. It has shown to be very useful in the ablation of atrial fibrillation by providing anatomic data on the left atrium and pulmonary veins, helping in transseptal punctures, locating the ostium and antrum of the pulmonary veins, monitoring tissue injury during radiofrequency (RF) use, preventing esophageal injury by monitoring the injuries caused by RF on the left atrial posterior wall and assessing the pulmonary vein flow. |
15,456 | Amiodarone-induced hypothyroidism and other adverse effects. | Amiodarone is a class III antiarrhythmic agent that is frequently prescribed today for the treatment of ventricular and atrial arrhythmias. Amiodarone has many adverse effects, and one of them is thyroid dysfunction. Advanced practice and staff nurses need to be vigilant, recognizing early signs and symptoms of thyroid dysfunction to prevent adverse drug reactions. Often, the signs and symptoms of amiodarone-induced hypothyroidism are overlooked because of the complexity of the patient's condition. The purpose of this article was to review a case study, present differential diagnoses and testing, discuss risk factors associated with amiodarone-induced hypothyroidism, discuss its pathogenesis, and review clinical management. |
15,457 | Inadvertent malposition of a permanent pacemaker ventricular lead into the left ventricle which was initially missed and diagnosed two years later: a case report. | Inadvertent malposition of a pacemaker ventricular lead into the left ventricle is an uncommon event, and its actual incidence is probably unknown. It may be underestimated and underreported because of a possible asymptomatic course. A 12-lead electrocardiogram is important to confirm proper placement.</AbstractText>We report a case of a 60-year-old Caucasian man with a malpositioned transvenous permanent pacing lead into the left ventricle via a patent foramen ovale that was not suspected during implantation and went undiagnosed for two years without complications. The patient remained asymptomatic as he was being treated with oral anticoagulation therapy for atrial fibrillation. The decision was made to leave the pacing lead in place and continue lifelong warfarin therapy.</AbstractText>Inadvertent insertion of pacing wires into the left ventricle is a potentially dangerous complication that may happen under fluoroscopic guidance and may be overlooked by routine pacemaker interrogation. It is advisable to obtain a 12-lead electrocardiogram during or immediately after transvenous pacemaker implantation rather than use a routine pacemaker interrogation or a limited electrocardiogram.</AbstractText> |
15,458 | ICD and neuromodulation devices: is peaceful coexistence possible? | The aim of this study was to investigate the potential cross-talk between implantable cardioverter defibrillator device (ICD) and implantable neuromodulation device (IND) during the implantation procedure and the ventricular fibrillation induction test and in daily life.</AbstractText>We present two cases of patients with an IND who underwent ICD implantation and one case of a patient implanted with a biventricular ICD who received an IND 6 months later. Two of these patients had a spinal cord stimulator (SCS), while the other had a sacral neuromodulator.</AbstractText>No cross-talk was recorded in the patient with the sacral neuromodulator and the ICD. Temporary damage to one of the SCSs was observed after multiple ICD shocks.</AbstractText>When implanted contemporarily with sacral or spinal neurostimulators, cardiac devices appear to be safe, as confirmed by the appropriate detection and interruption of arrhythmic episodes. On the other hand, neuromodulation devices could be temporarily or permanently damaged by multiple ICD discharges. It is recommended that the neurostimulator be interrogated after an ICD shock, in order to check the state of the device.</AbstractText>©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.</CopyrightInformation> |
15,459 | Intracellular calcium and the mechanism of anodal supernormal excitability in langendorff perfused rabbit ventricles. | Anodal stimulation hyperpolarizes the cell membrane and increases the intracellular Ca(2+) (Ca(i)) transient. This study tested the hypothesis that the maximum slope of the Ca(i) decline (-(dCa(i)/dt)(max)) corresponds to the timing of anodal dip on the strength-interval curve and the initiation of repetitive responses and ventricular fibrillation (VF) after a premature stimulus (S(2)).</AbstractText>We simultaneously mapped the membrane potential (V(m)) and Ca(i) in 23 rabbit ventricles. A dip in the anodal strength-interval curve was observed. During the anodal dip, ventricles were captured by anodal break excitation directly under the S(2) electrode. The Ca(i) following anodal stimuli is larger than that following cathodal stimuli. The S(1)-S(2) intervals of the anodal dip (203±10 ms) coincided with the -(dCa(i)/dt)(max) (199±10 ms, P=NS). BAPTA-AM (n=3), inhibition of the electrogenic Na(+)-Ca(2+) exchanger current (I(NCX)) by low extracellular Na(+) (n=3), and combined ryanodine and thapsigargin infusion (n=2) eliminated the anodal supernormality. Strong S(2) during the relative refractory period (n=5) induced 29 repetitive responses and 10 VF episodes. The interval between S(2) and the first non-driven beat was coincidental with the time of -(dCa(i)/dt)(max).</AbstractText>Larger Ca(i) transient and I(NCX) activation induced by anodal stimulation produces anodal supernormality. The time of maximum I(NCX) activation is coincidental to the induction of non-driven beats from the Ca(i) sinkhole after a strong premature stimulation.</AbstractText>All rights are reserved to the Japanese Circulation Society.</CopyrightInformation> |
15,460 | A comparison of single-lead atrial pacing with dual-chamber pacing in sick sinus syndrome. | In patients with sick sinus syndrome, bradycardia can be treated with a single-lead pacemaker or a dual-chamber pacemaker. Previous trials have revealed that pacing modes preserving atrio-ventricular synchrony are superior to single-lead ventricular pacing, but it remains unclear if there is any difference between single-lead atrial pacing (AAIR) and dual-chamber pacing (DDDR).</AbstractText>We randomly assigned 1415 patients referred for first pacemaker implantation to AAIR (n = 707) or DDDR (n = 708) pacing and followed them for a mean of 5.4 ± 2.6 years. The primary outcome was death from any cause. Secondary outcomes included paroxysmal and chronic atrial fibrillation, stroke, heart failure, and need for pacemaker reoperation. In the AAIR group, 209 patients (29.6%) died during follow-up vs. 193 patients (27.3%) in the DDDR group, hazard ratio (HR) 1.06, 95% confidence interval (CI) 0.88-1.29, P = 0.53. Paroxysmal atrial fibrillation was observed in 201 patients (28.4%) in the AAIR group vs. 163 patients (23.0%) in the DDDR group, HR 1.27, 95% CI 1.03-1.56, P = 0.024. A total of 240 patients underwent one or more pacemaker reoperations during follow-up, 156 (22.1%) in the AAIR group vs. 84 (11.9%) in the DDDR group (HR 1.99, 95% CI 1.53-2.59, P < 0.001). The incidence of chronic atrial fibrillation, stroke, and heart failure did not differ between treatment groups.</AbstractText>In patients with sick sinus syndrome, there is no statistically significant difference in death from any cause between AAIR pacing and DDDR pacing. AAIR pacing is associated with a higher incidence of paroxysmal atrial fibrillation and a two-fold increased risk of pacemaker reoperation. These findings support the routine use of DDDR pacing in these patients.</AbstractText>URL http://www.clinicaltrials.gov. Unique identifier: NCT00236158.</AbstractText> |
15,461 | Cardiac sarcoidosis and sudden death. The heart may look normal or mimic other cardiomyopathies. | Cardiac sarcoidosis has been known to give rise to heart failure, arrhythmias and sudden cardiac death. We have a large database of sudden cardiac death cases at the CRY Centre for Cardiac Pathology at Imperial College, London, UK in which we found 17 of 1,720 cases with a diagnosis of cardiac sarcoid. Macroscopic examination showed a variety of findings including left ventricular hypertrophy, a dilated thin-walled left ventricle, areas of fibrosis, changes resembling arrhythmogenic right ventricular cardiomyopathy and in some cases, no gross abnormalities. Histological examination revealed large areas of fibrosis and focal lymphocytic inflammation mimicking infarction/myocarditis. Careful search had to be made for non-necrotizing granulomata, since the lymphocytic foci, fibrosis and granulation tissue often predominated throughout the heart. The conduction tissue is often not sampled at autopsy despite the history of heart block. The heterogeneous nature of the macroscopic appearance and histological findings means that widespread sampling of the heart and the conduction system is essential in cases of sudden death in order that a diagnosis of myocardial sarcoidosis is not missed. |
15,462 | Incidence, risk factors, and consequences of new-onset atrial fibrillation following epicardial ablation for ventricular tachycardia. | We sought to determine the incidence, predictors, and consequences of new-onset atrial fibrillation (AF) following epicardial ventricular tachycardia (VT) ablation.</AbstractText>A total of 41 patients with no prior history of AF underwent epicardial VT ablation via a percutaneous subxiphoid approach. All patients were monitored continuously for 3 days following ablation and then via implantable cardiac defibrillator (ICD) or Holter monitoring. Mean age was 70.0 ± 11.3 years and mean ejection fraction was 30.3 ± 16.6%. In seven (17%) patients, the right ventricle (RV) was punctured during access with subsequent needle withdrawal without requiring surgical repair. Thirty patients (73%) were treated with amiodarone following ablation. Post-ablation, eight (19.5%) patients had documented new-onset AF within 7 days. All AF patients had clinical symptoms of pericarditis. One patient with AF was maintained on amiodarone post-procedure. Complications of AF included three patients who received inappropriate ICD shocks and one patient who developed a large, left atrial appendage clot. Acutely, all patients responded to short-term medical therapy or electrical cardioversion. At 18.0 ± 9.0 months of follow-up, no patient had recurrence of AF, and all were off antiarrhythmic drugs. One patient had typical atrial flutter requiring catheter ablation. Risk factors for AF included lack of amiodarone immediately after ablation (12.5 vs. 87.9%, P < 0.001), RV puncture (50.0 vs. 9.1%, P = 0.02), and epicardial ablation time >10 min (62.5 vs. 3.0%, P < 0.001).</AbstractText>Atrial fibrillation after epicardial ablation is common and can lead to ICD shocks and atrial thrombus formation. Short-term antiarrhythmic drug therapy and ICD reprogramming should be considered after epicardial VT ablation.</AbstractText> |
15,463 | Atrial cardiomyocyte calcium signalling. | Whereas Ca(2+) signalling in ventricular cardiomyocytes is well described, much less is known regarding the Ca(2+) signals within atrial cells. This is surprising given that atrial cardiomyocytes make an important contribution to the refilling of ventricles with blood, which enhances the subsequent ejection of blood from the heart. The dependence of cardiac function on the contribution of atria becomes increasingly important with age and exercise. Disruption of the rhythmic beating of atrial cardiomyocytes can lead to life-threatening conditions such as atrial fibrillation. Atrial and ventricular myocytes have many structural and functional similarities. However, one key structural difference, the lack of transverse tubules ("T-tubules") in atrial myocytes, make these two cell types display vastly different calcium patterns in response to electrical excitation. The lack of T-tubules in atrial myocytes means that depolarisation provokes calcium signals that originate around the periphery of the cells. Under resting conditions, such Ca(2+) signals do not propagate towards the centre of the atrial cells and so do not fully engage the contractile machinery. Consequently, contraction of atrial myocytes under resting conditions is modest. However, when atrial myocytes are stimulated with a positive inotropic agonist, such as isoproterenol, the peripheral Ca(2+) signals trigger a global wave of Ca(2+) that propagates in a centripetal manner into the cells. Enhanced centripetal movement of Ca(2+) in atrial myocytes leads to increased contraction and a more substantial contribution to blood pumping. This article is part of a Special Issue entitled: 11th European Symposium on Calcium. |
15,464 | Self-terminated ventricular fibrillation and recurrent syncope. | Ventricular fibrillation (VF) is a lethal arrhythmia that requires immediate cardioversion and is rarely self-terminating. Spontaneous termination is typically associated with more organized activation than sustained VF terminated by shock, but the precise mechanism is unclear. In the present case, we describe a patient with recurrent syncope and documented self-terminating VF, who ultimately underwent implantable cardioverter defibrillator insertion. Assessment of the rhythm strip revealed organization of a chaotic rhythm into monomorphic ventricular tachycardia before termination, in supportive of previous reports. In conclusion, self-terminating VF is a very rare condition that can cause syncope. |
15,465 | Risk of sudden death among young individuals with J waves and early repolarization: putting the evidence into perspective. | The presence of J waves and ST-segment elevation on the electrocardiogram (ECG), jointly termed "the early repolarization pattern," has traditionally been considered a marker of "good health." However, recent case control series and long-term population studies have established a statistically significant association between this ECG pattern and an increased risk for arrhythmic death. This finding has raised concern among physicians, who now are asked to estimate the "arrhythmic risk" following the incidental discovery of J waves on routine ECG. Therefore, we review the literature linking early repolarization with arrhythmic risk to place this "fear of J waves" in the right perspective. We found five case control studies (involving 331 patients with idiopathic ventricular fibrillation [VF] and 8,649 controls). All of these studies showed that J waves, particularly of large amplitude and recorded in multiple leads, are more prevalent among patients with idiopathic VF. We also found three large population studies (involving >17,000 individuals) looking at the prognostic value of early repolarization. Two of these studies showed that the presence of J waves >2 mm in amplitude in asymptomatic adults is associated with a threefold increased of arrhythmic death during very long-term follow-up. Individuals with J waves do have some degree of increased dispersion of repolarization that places them at increased risk for arrhythmic death, but only in the presence of additional proarrhythmic factors or triggers. A sensible approach for the asymptomatic patient with J waves is proposed. |
15,466 | Successful treatment of catecholaminergic polymorphic ventricular tachycardia with flecainide: a case report and review of the current literature. | Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disease that can cause sudden cardiac death due to ventricular fibrillation (VF). While pharmacological therapy with beta-blockers and/or Ca(2)(+) antagonists is often unreliable, a recent study has demonstrated that flecainide can effectively suppress arrhythmia in a murine model of CPVT as well as clinically in two human subjects suffering from CPVT. We here present the case of an 11-year-old boy suffering from CPVT-1 as well as a review of the current relevant literature. After resuscitation due to VF at age 9, an automated implantable cardioverter-defibrillator (ICD) was implanted in 2007. Under beta-blocker therapy, repeated shocks were delivered due to either fast ventricular tachycardia (VT) or VF. This persisted under additional therapy with verapamil. Implantable cardioverter-defibrillator routine interrogations showed frequent non-sustained VT with an average of 8.8 per day. Additionally, the patient suffered from impaired physical performance due to decreased chronotropic competence. In July 2009, flecainide was added to the beta-blocker/verapamil regimen, resulting in a plasma level of 0.20 mg/L. No ICD shock or sustained VT occurred until December 2010. Genetic testing revealed an RyR2 receptor mutation. The case demonstrates the challenge of diagnosis and management of CPVT. It furthermore supports recent experimental evidence that the class 1 antiarrhythmic drug flecainide can suppress CPVT. The presented case supports a novel strategy in treating CPVT with the class I antiarrhythmic agent flecainide. |
15,467 | [Aneurysmal dilatation of pulmonary artery and its branches on mitral stenosis: a case report]. | Pulmonary arteries aneurysms are rare and the rarely described bilateral aneurysms. A 45-year-old patient carrier of mitral stenosis was admitted for dyspnoea class III of the NYHA, chest pain and a not infectious cough. The clinical examination found semiology of mitral stenosis, tricuspid incapacity and pulmonary arterial hypertension. The electrocardiogram showed atrial fibrillation and right ventricle hypertrophy. Chest X-ray found a cardiomegaly, an aspect of double outline of the inferior right bow, a prominent aspect of the left average bow reminding an aneurysm of the left pulmonary artery. The echocardiography Doppler found a pure tight mitral stenosis (mitral surface=0.6 cm(2)), a dilation of the trunk of the pulmonary artery (diameter=74 mm) and of its branches (diameter of the right pulmonary artery=28 mm, diameter of the left pulmonary artery=36 mm) seat of a spontaneous contrast. The left atrium and right cardiac cavities were also dilated. There was an important tricuspid incapacity with a major pulmonary hypertension (systolic pulmonary arterial=109 mmHg). The thoracic angioscan showed a pseudoaneurysm of the trunk of pulmonary artery and its branches to their distal parts. Under diuretic, anticoagulating and analgesic treatment the clinical signs improved however the spontaneous contrast persisted. The patient was rejected by the surgery for exceeded clinical board. She is at present followed in our service for 5 months. |
15,468 | Intracoronary delivery of mesenchymal stem cells reduces proarrhythmogenic risks in swine with myocardial infarction. | The electrophysiological consequences of mesenchymal stem cell (MSC) therapy in ischemic heart disease have not been fully understood.</AbstractText>Swine myocardial infarction (MI) model by intracoronary balloon occlusion received MSC solution or 0.9% NaCl. Six weeks later, heart rate turbulence (HRT), dispersion of action potential durations (APD) and repolarization time (RT) (APDd and RTd), slope of APD reconstitution curve and programmed electrical stimulation were used to evaluate the ventricular arrhythmic risks.</AbstractText>MSC treatment could significantly ameliorate the abnormal HRT, APD(90), APDd, RT and RTd. The slope of APD reconstitution curve in MSC group was higher than control group but lower than MI group. MSC therapy markedly reduced inducible malignant ventricular arrhythmias (VAs), and improved impaired cardiac performances and cardiac fibrosis.</AbstractText>This study provides strong evidence that MSC infusion via intracoronary route does not cause VAs but tends to reduce the risk of malignant VAs.</AbstractText> |
15,469 | [Heart failure. Excitation-contraction coupling and novel therapeutic options]. | Heart failure (HF) is a disease with an increasing prevalence and results in both reduced quality of life and decreased lifespan for patients. Despite improved therapy mortality remains very high. HF is induced by events that lead to reduced function of the heart, e.g. myocardial infarction and increased chronic afterload through arterial hypertension. For compensation to occur, neurohumoral mechanisms temporarily maintain cardiac function. Over time this results in left ventricular remodelling and, by means of a vicious circle, compensated HF becomes symptomatic HF. The myocardium of patients with HF is characterised by a dysfunction in excitation-contraction coupling (ECC), which causes reduced cell contractility due to reduced Ca(2+) transients and SR Ca(2+) load. The Ca(2+)/calmodulin-dependent protein kinase IIδ (CaMKIIδ) plays an important role in the onset of HF. CaMKIIδ phosphorylates several functional key proteins, leads to reduced SR Ca(2+) load and Ca(2+)-transients in HF, acts as an arrhythmogenic protein by increasing late I(Na), and contributes to diastolic dysfunction by accumulation of intracellular Ca(2+). CaMKIIδ also plays an important role in atrial fibrillation. Interestingly, with regard to increased cardiac load, CaMKIIδ is activated in increased afterload but not in preload. The important role of CaMKIIδ in HF implies new therapeutic options to improve HF therapy in the future. |
15,470 | Future easy and physiological cardiac pacing. | The right atrial appendage (RAA) and right ventricular apex (RVA) have been widely considered as conventional sites for typical dual-chamber atrio-ventricular cardiac (DDD) pacing. Unfortunately conventional RAA pacing seems not to be able to prevent atrial fibrillation in DDD pacing for tachycardia-bradycardia syndrome, and the presence of a left bundle branch type of activation induced by RVA pacing can have negative effects. A new technology with active screw-in leads permits a more physiological atrial and right ventricular pacing. In this review, we highlight the positive effects of pacing of these new and easily selected sites. The septal atrial lead permits a shorter and more homogeneous atrial activation, allowing better prevention of paroxysmal atrial fibrillation. The para-Hisian pacing can be achieved in a simpler and more reliable way with respect to biventricular pacing and direct Hisian pacing. We await larger trials to consider this "easy and physiological pacing" as a first approach in patients who need a high frequency of pacing. |
15,471 | Atrial fibrillation ablation induces reverse remodelling and impacts cardiac function. | Atrio-ventricular anatomo-functional response to successful surgical atrial fibrillation (AF) ablation has been poorly investigated. Determinants of AF recurrence following surgical ablation are still debated.</AbstractText>Sixty-nine patients underwent AF ablation during major cardiac surgery. Main outcomes were clinical and echocardiographic results after monopolar and/or bipolar ablation were recorded. Secondary outcomes were freedom from AF, rehospitalization and congestive heart failure (CHF) at follow-up. Predictors of AF-recurrence were evaluated.</AbstractText>Fifty-three patients (76.8%) were in sinus rhythm (SR) at 31.4±10.6 months of mean follow-up. Overall freedom from AF-recurrence was 61.4±6.6%, from hospital readmission 89.9±3.6%, from CHF 91.9±5.05%. Compared to AF-patients, SR-patients demonstrated better freedom from re-hospitalization (98.1±1.9% vs. 62.5±12.1%; P=0.0001) and CHF (94.7±5.1% vs. 77.8±13.9%; P=0.006). At follow-up SR-patients demonstrated atrial (preoperative 5.9±1.2 cm vs. follow-up 5.2±1.0; P=0.01) and ventricular reverse remodelling (preoperative LVDd 5.8±1.6cm vs. follow-up 5.0±1.3 cm; P=0.002 - preoperative LVDs 4.2±1.8 cm vs. follow-up 3.8±1.2 cm; P=0.045). E/A ratio was normal in 90.6% of SR-patients (69.6% of the total population of the study). TDI at the level of the left lateral annulus showed an improved left ventricular systole (Sm), and diastole (Em, E/Em) for SR-patients compared to AF-patients (Sm 9.30±1.66 vs. 7.81±1.41, P=0.001; Em: 10.55±1.87 vs. 7.44±0.40, P=0.001; E/Em: 0.06±0.02 vs. 0.11±0.05, P=0.0001). Preoperative atrial diameter (OR=23.9; P=0.002) and tricuspid insufficiency at follow-up (OR=3.5; P=0.008) were independent predictors of AF-recurrence. Neither etiology, nor duration of AF, nor even ablation technique influenced SR recovery (P=NS for all measurement).</AbstractText>Radiofrequency AF ablation achieves 76.8% of SR recovery at follow-up. Maintenance of SR improves clinical, haemodynamic and echocardiographic results.</AbstractText> |
15,472 | Mitochondrial uncoupling agents trigger ventricular fibrillation in isolated rat hearts. | Sudden cardiac death resulting from ventricular fibrillation (VF) remains a major cause of mortality. The purpose of this study was to investigate the roles of loss of oxidative phosphorylation and activation of the mitochondrial ATP-sensitive K+ channel and permeability transition pore in VF development during myocardial ischemia by using mitochondrial uncoupling agents (carbonyl cyanide m-chlorophenylhydrazone and 2,4-dinitrophenol) and channel blockers (5-hydroxydecanoate and cyclosporine A) at concentrations that have been demonstrated to block the intended targets selectively. Isolated rat hearts (n = 8 per group) were perfused with 0.3 μM carbonyl cyanide m-chlorophenylhydrazone, 100 μM 2,4-dinitrophenol, 0.2 μM cyclosporine A, 100 μM 5-hydroxydecanoate, or vehicle solution and regional ischemia induced after 10 minutes. Carbonyl cyanide m-chlorophenylhydrazone and 2,4 dinitrophenol caused profound QT shortening and triggered VF in 100% of hearts before ischemia. During ischemia, neither cyclosporine A (88%) nor 5-hydroxydecanoate (100%) reduced VF incidence compared with control (100% VF). In separate hearts, carbonyl cyanide m-chlorophenylhydrazone decreased tissue ATP content, and glibenclamide or glimepiride delayed the QT shortening and onset of VF triggered by carbonyl cyanide m-chlorophenylhydrazone. In conclusion, mitochondrial uncoupling agents trigger VF, likely as a result of ATP depletion with subsequent activation of sarcolemmal ATP-sensitive K+ currents. The mechanism of VF in ischemia does not involve activation of the mitochondrial ATP-sensitive K+ channel or permeability transition pore. |
15,473 | Reduced antiarrhythmic efficacy of verapamil in isolated rat hearts in the presence of elevated extracellular calcium. | An isolated heart method that has been proposed to aid in ascertaining the involvement of L-type calcium channel blockade in the mechanism of action of novel antiarrhythmic drugs involves increasing the calcium concentration in the perfusion buffer. The purpose of this study was to determine the validity of this method using an established L-type calcium channel blocker, verapamil. Isolated rat hearts were perfused with normal calcium (1.4 mM) Krebs solution containing drug vehicle only, a normal calcium solution containing verapamil (300 nM), or a high calcium (2.8 mM) solution containing verapamil. The occurrence of ventricular fibrillation during a subsequent period of regional myocardial ischemia was monitored. The incidence of ventricular fibrillation was significantly reduced from 80% in controls to 20% by perfusion with verapamil in normal calcium Krebs solution (P < 0.05). Perfusion with the high calcium solution increased the incidence of ventricular fibrillation in the presence of verapamil to 40% (P > 0.05 versus controls). We conclude that the antiarrhythmic effect of verapamil in isolated hearts can be attenuated by increasing the calcium content of the perfusion solution, but a twofold increase in the calcium concentration failed to fully restore susceptibility to ventricular fibrillation to that observed in verapamil-free controls. |
15,474 | Heritability of early repolarization: a population-based study. | Early repolarization (ER), defined by J-point elevation in 12-lead ECG, was recently associated with increased risk for idiopathic ventricular fibrillation and cardiovascular mortality. The determinants of ER are unknown. We investigated its heritability in a large, family-based cohort.</AbstractText>The study sample comprised 1877 individuals from 505 white nuclear families representative of the British general population. Standard 12-lead ECGs were evaluated for the presence of ER, defined as J-point elevation of ≥0.1 mV in at least 2 adjacent inferior (II, III, and aVF) or anterolateral (I, aVL, and V(4) through V(6)) leads. Narrow sense heritability estimates were computed adjusting for age, age(2), and sex. The prevalence of ER was 7.7% (n=145) in the whole cohort, 5.9% (n=56) in parents, and 9.6% (n=89) in offspring. Heritability estimate for the presence of ER was calculated at h(2)=0.49 (standard error=0.14; P=2.7*10(-4)) and was higher when restricted to its presence in inferior leads (h(2)=0.61, standard error=0.18, P=4.3*10(-4)) or for the notching ER morphology (h(2)=0.81, standard error=0.19, P=2.4*10(-5)). Individuals with at least 1 affected parent had a 2.5-fold increased risk for presenting with ER on ECG (odds ratio, 2.54; 95% confidence interval, 1.33 to 4.84; P=0.005). Familial transmission was more frequent when the mother was affected (odds ratio, 3.84; 95% confidence interval, 1.41 to 10.43; P=0.008) than when the father was affected (odds ratio, 1.82; 95% confidence interval, 0.82 to 4.03; P=0.141), although this difference was not statistically significant (P=0.18).</AbstractText>ER is a heritable phenotype. Offspring of ER-positive parents have a 2.5-fold increased risk of presenting with ER on their ECG.</AbstractText> |
15,475 | [Heart failure and anaphylactic shock. A report of two cases]. | Anaphylactic shock can sometimes take the appearance of heart failure, in relation to an acute coronary syndrome, even with normal coronary arteries, that we illustrate by two observations. We firstly report the case of an anaphylactic shock caused by succinylcholine, after anesthesia induction for inguinal hernia surgery in a 50-year-old man with cardiovascular risks, who presented with ventricular fibrillation followed by a cardiac arrest. An acute and severe anterior coronary syndrome was suspected and treated with thrombolysis. Then the electrocardiogram normalized, as well as the left ventricular function. No significant coronary stenosis was retrospectively revealed by coronarography, and a severe coronary vasospasm induced by the anaphylactic reaction was confirmed. We also describe the case of an anaphylactoid shock caused by cisatracurium infusion, that occurred at the beginning of an adnexectomy in a 55-year-old woman without any particular history. She presented with a cardiogenic shock after intravenous administration of epinephrine. The echocardiograpghic evaluation pointed out an aspect of stress-induced cardiomyopathy, and the coronarography showed normal coronary arteries. The left ventricular dysfunction completely normalized, strongly suggesting the diagnosis of Takotsubo-like syndrome after the anaphylactic shock and its treatment. Both of these cases point out the major interest of cardiologic and allergic evaluation in case of heart failure during general anesthesia. Coronary vasospasm and stress-induced cardiomyopathy are two pathologies that may be observed during anaphylactic shock, and their diagnosis should be considered after elimination of coronary thrombosis. |
15,476 | [Management of cardiac arrhythmias during pregnancy]. | Pregnancy can precipitate or exacerbate cardiac arrhythmias. Management of those arrhythmias is not very different from that in non-pregnant women.</AbstractText>In this review we tried to specify factors which favour arrhythmias in pregnant women and to show their specific management.</AbstractText>We carried out a search through PubMed using as keywords: pregnancy, cardiac arrhythmias, antiarrhythmics.</AbstractText>Hemodynamic perturbations, direct electrophysiological effects of hormones and underlying heart disease are potential factors that can promote arrhythmias in pregnancy. Usually, no drug therapy is needed for the management of supraventricular or ventricular premature beats but potential promoting factors should be eliminated. In paroxysmal supraventricular tachycardia, vagal maneuvers should be tried firstly. Adenosine could be used if vagal maneuvers are ineffective. In pregnant women with atrial fibrillation, the goal of treatment is the conversion to sinus rhythm or the control of ventricular rate. Ventricular arrhythmias are usually uncommon during pregnancy and often occur in the absence of structural heart disease and are responsive to drug therapy. Symptomatic bradycardia rarely complicates pregnancy and its management does not differ from that in non-pregnant women.</AbstractText>Copyright © 2010 Elsevier Masson SAS. All rights reserved.</CopyrightInformation> |
15,477 | Granulocyte colony-stimulating factor stabilizes cardiac electrophysiology and decreases infarct size during cardiac ischaemic/reperfusion in swine. | Effects of granulocyte colony-stimulating factor (G-CSF) on cardiac electrophysiology during ischaemic/reperfusion (I/R) period are unclear. We hypothesized that G-CSF stabilizes cardiac electrophysiology during I/R injury by prolonging the effective refractory period (ERP), increasing the ventricular fibrillation threshold (VFT) and decreasing the defibrillation threshold (DFT), and that the cardioprotection of G-CSF is via preventing cardiac mitochondrial dysfunction.</AbstractText>In intact-heart protocol, pigs were infused with either G-CSF or vehicle (n = 7 each group) without I/R induction. In I/R protocol, pigs were infused with G-CSF (0.33 μg kg(-1 ) min(-1) ) or vehicle (n = 8 each group) for 30 min prior to a 45-min left anterior descending artery occlusion and at reperfusion. Diastolic pacing threshold (DPT), ERP, VFT and DFT were determined in all pigs before and during I/R period. Rat's isolated cardiac mitochondria were used to test the protective effect of G-CSF (100 nm) in H(2) O(2) -induced mitochondrial oxidative damage.</AbstractText>Neither G-CSF nor vehicle altered any parameter in intact-heart pigs. During ischaemic period, G-CSF significantly increased the DPT, ERP and VFT without altering the DFT. During reperfusion, G-CSF continued to increase the DPT without altering other parameters. The infarct size was significantly decreased in the G-CSF group, compared to the vehicle. G-CSF could also prevent cardiac mitochondrial swelling, decrease ROS production, and prevent mitochondrial membrane depolarization.</AbstractText>G-CSF increases the DPT, ERP and VFT and reduces the infarct size, thus stabilizing the myocardial electrophysiology, and preventing fatal arrhythmia during I/R. The protective mechanism could be via its effect in preventing cardiac mitochondrial dysfunction.</AbstractText>© 2011 The Authors. Acta Physiologica © 2011 Scandinavian Physiological Society.</CopyrightInformation> |
15,478 | Intravenous vernakalant: a review of its use in the management of recent-onset atrial fibrillation. | Intravenous vernakalant (Brinavess®) is an atrial-repolarization-delaying agent that is currently approved in the EU for the rapid conversion of recent-onset atrial fibrillation to sinus rhythm. Vernakalant blocks atrial-specific potassium and sodium ion channels, prolonging atrial refractory periods and rate-dependently slowing atrial conduction, without promoting ventricular arrhythmia. In pivotal randomized, phase III trials, intravenous vernakalant 3 mg/kg administered as a 10-minute infusion, followed by a 2 mg/kg 10-minute infusion after 15 minutes if atrial fibrillation persisted, was effective in the rapid termination of recent-onset atrial fibrillation in nonsurgical patients (≥3 hours' to ≤7 days' duration) and in those with postoperative atrial fibrillation (3-72 hours' duration) following cardiac surgery. Conversion to sinus rhythm occurred rapidly following infusion of vernakalant, with the majority of patients converting after the first dose, and conversion to sinus rhythm was generally associated with a rapid resolution of symptoms. These antiarrhythmic effects of vernakalant were durable, with most responders remaining in sinus rhythm 24 hours after treatment initiation. In nonsurgical patients with recent-onset atrial fibrillation of 3-48 hours' duration, vernakalant was more effective than intravenous amiodarone, with a significantly higher proportion of patients converting to sinus rhythm within the first 90 minutes of treatment. Vernakalant was generally well tolerated in clinical trials, with most adverse events being of mild or moderate severity and not treatment limiting. Increases in QRS or QT intervals were transient, and there was no increased incidence of ventricular arrhythmia observed with vernakalant compared with placebo. Therefore, intravenous vernakalant provides an effective option for the management of recent-onset atrial fibrillation. |
15,479 | Prevention and reversal of atrial fibrillation inducibility and autonomic remodeling by low-level vagosympathetic nerve stimulation. | We hypothesized that autonomic atrial remodeling can be reversed by low-level (LL) vagosympathetic nerve stimulation (VNS).</AbstractText>Previously, we showed that VNS can be antiarrhythmogenic.</AbstractText>Thirty-three dogs were subjected to electrical stimulation (20 Hz) applied to both vagosympathetic trunks at voltages 10% to 50% below the threshold that slowed sinus rate or AV conduction. Group 1 (n = 7): Programmed stimulation (PS) was performed at baseline and during 6-h rapid atrial pacing (RAP). PS allowed determination of effective refractory period (ERP) and AF inducibility measured by window of vulnerability (WOV). LL-VNS was continuously applied from the 4th to 6th hours. Group 2 (n = 4): After baseline ERP and WOV determinations, 6-h concomitant RAP+LL-VNS was applied. Sustained AF was induced by injecting acetylcholine (ACh) 10 mM into the anterior right ganglionated plexus (Group 3, n = 10) or applying ACh 10 mM to right atrial appendage (Group 4, n = 9).</AbstractText>Group 1: The ERP progressively shortened and the ΣWOV (sum of WOV from all tested sites) progressively increased (p < 0.05) during 3-h RAP then returned toward baseline during 3-h RAP+LL-VNS (p < 0.05). Group 2: 6-h concomitant RAP+LL-VNS did not induce any significant change in ERP and ΣWOV. Group 3 and Group 4: AF duration (AF-D) and cycle length (AF-CL) were markedly altered by 3-h LL-VNS (Group 3: baseline: AF-D = 389 ± 90 s, AF-CL = 45.1 ± 7.8 ms; LL-VNS: AF-D = 50 ± 15 s, AF-CL = 82.0 ± 13.7 ms [both p < 0.001]; Group 4: baseline: AF-D = 505 ± 162 s, AF-CL = 48.8 ± 6.6 ms; LL-VNS: AF-D = 71 ± 21 s, AF-CL = 101.3 ± 20.9 ms [both p < 0.001]).</AbstractText>LL-VNS can prevent and reverse atrial remodeling induced by RAP as well as suppress AF induced by strong cholinergic stimulation. Inhibition of the intrinsic cardiac autonomic nervous system by LL-VNS may be responsible for these salutary results.</AbstractText>Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,480 | [Unexpected complication following esophageal variceal hemorrhage - Case 2/2011]. | A 50-year-old patient with alcoholic liver cirrhosis was admitted due to hematemesis and melaena.</AbstractText>Endoscopy showed esophageal variceal hemorrhage. A dose of erythromycin was administered before endoscopy for optimal endoscopic view.</AbstractText>After conservative treatment with hemopressin, ciprofloxacin, and substitution with blood and fresh frozen plasma, the patient had an episode of atrial fibrillation with rapid ventricular response. The episode was terminated by intravenous administration of amiodarone, with subsequent conversion to sinus rhythm. Later on, the patient suffered from torsades de pointes tachycardia.</AbstractText>Secondary torsades de pointes tachycardias have a low incidence, but often fatal outcome. Torsades de pointes tachycardias mostly are the result of administration of QT-active drugs, and other cofactors. Emergency treatment addresses the reestablishment, and stabilization of sinus rhythm. Preferably, drug-induced torsades de pointes tachycardias are prevented by permanent critical review of administered drugs with respect to indications, interactions, and adverse reactions.</AbstractText> |
15,481 | Temporal and spectral analysis of ventricular fibrillation in humans. | Analysing ventricular fibrillation (VF) rate and regularity at different sites and at different times may help understanding some of the mechanisms underlying VF in humans.</AbstractText>Twelve episodes of VF (19.4 ± 5.6 s) were induced during electrophysiological study in eight men (63 ± 14 years old). Calculation of dominant frequency (DF) by fast Fourier transform, short-time Fourier transform, and analysis of the pitch frequency [VF cycle length duration (CL)] were performed. For each episode, we analysed the 12 lead-surface ECG, three unipolar, 10 near-field, and three far-field bipolar recordings by means of three quadripolar catheters positioned at the right ventricular apex (RV apex), right ventricular outflow tract, and at the coronary sinus (exploring the lateral left ventricular epicardium) (LV).</AbstractText>Fast and regular discrete activation covered the whole duration of every intracardiac recording, whereas surface ECG consistently displayed chaotic and fibrillatory pattern. DF (5.25 ± 0.64 Hz) was very similar on surface ECG recordings and in various intracardiac recordings. Intracardiac activation was rather regular during VF despite the fibrillatory process with very low SD of the CL. There were some significant inverse correlations between VF rate and VF regularity. Intracardiac sites displaying the fastest and most regular activations were those including the RV apex. VF rate and stability slightly increased over time. Finally, the parameters exploring the VF rate were found to be well correlated together, as well as parameters of VF regularity</AbstractText>Human VF induced during electrophysiological study has a clear DF of activation and appears quite regular in intracardiac recordings. There is some spatial heterogeneity, which needs to be more detailed in order to localize possible driving sources. Fastest VF are the most regular. Rate and stability tend to increase during the initial phases of VF.</AbstractText> |
15,482 | Ventricular tachyarrhythmias after cardiac arrest in public versus at home. | The incidence of ventricular fibrillation or pulseless ventricular tachycardia as the first recorded rhythm after out-of-hospital cardiac arrest has unexpectedly declined. The success of bystander-deployed automated external defibrillators (AEDs) in public settings suggests that this may be the more common initial rhythm when out-of-hospital cardiac arrest occurs in public. We conducted a study to determine whether the location of the arrest, the type of arrhythmia, and the probability of survival are associated.</AbstractText>Between 2005 and 2007, we conducted a prospective cohort study of out-of-hospital cardiac arrest in adults in 10 North American communities. We assessed the frequencies of ventricular fibrillation or pulseless ventricular tachycardia and of survival to hospital discharge for arrests at home as compared with arrests in public.</AbstractText>Of 12,930 evaluated out-of-hospital cardiac arrests, 2042 occurred in public and 9564 at home. For cardiac arrests at home, the incidence of ventricular fibrillation or pulseless ventricular tachycardia was 25% when the arrest was witnessed by emergency-medical-services (EMS) personnel, 35% when it was witnessed by a bystander, and 36% when a bystander applied an AED. For cardiac arrests in public, the corresponding rates were 38%, 60%, and 79%. The adjusted odds ratio for initial ventricular fibrillation or pulseless ventricular tachycardia in public versus at home was 2.28 (95% confidence interval [CI], 1.96 to 2.66; P < 0.001) for bystander-witnessed arrests and 4.48 (95% CI, 2.23 to 8.97; P<0.001) for arrests in which bystanders applied AEDs. The rate of survival to hospital discharge was 34% for arrests in public settings with AEDs applied by bystanders versus 12% for arrests at home (adjusted odds ratio, 2.49; 95% CI, 1.03 to 5.99; P = 0.04).</AbstractText>Regardless of whether out-of-hospital cardiac arrests are witnessed by EMS personnel or bystanders and whether AEDs are applied by bystanders, the proportion of arrests with initial ventricular fibrillation or pulseless ventricular tachycardia is much greater in public settings than at home. The incremental value of resuscitation strategies, such as the ready availability of an AED, may be related to the place where the arrest occurs.</AbstractText> |
15,483 | [Ventricular fibrillation effectively treated by wearable automatic defibrillator - a case report]. | We present a patient at risk of sudden cardiac death in whom ventricular fibrillation was effectively treated by wearable automatic defibrillator. We discuss the technical aspects of the device, current indications for this therapy and outcomes. |
15,484 | Ventricular fibrillation associated with occult eating disorder - a clinical puzzle. | Eating disorders are not infrequent in adolescents, and associated cardiac arrhythmias (CA) are well described in these patients. However, CA in adult eating disorders have been reported only rarely. We report a case of ventricular fibrillation in a patient presenting with fatigue and a recent history of vomiting. |
15,485 | Vernakalant selectively prolongs atrial refractoriness with no effect on ventricular refractoriness or defibrillation threshold in pigs. | Vernakalant is a novel antiarrhythmic agent that has demonstrated clinical efficacy for the treatment of atrial fibrillation. Vernakalant blocks, to various degrees, cardiac sodium and potassium channels with a pattern that suggests atrial selectivity. We hypothesized, therefore, that vernakalant would affect atrial more than ventricular effective refractory period (ERP) and have little or no effect on ventricular defibrillation threshold (DFT). Atrial and ventricular ERP and ventricular DFT were determined before and after treatment with vernakalant or vehicle in 23 anesthetized male mixed-breed pigs. Vernakalant was infused at a rate designed to achieve stable plasma levels similar to those in human clinical trials. Atrial and ventricular ERP were determined by endocardial extrastimuli delivered to the right atria or right ventricle. Defibrillation was achieved using external biphasic shocks delivered through adhesive defibrillation patches placed on the thorax after 10 seconds of electrically induced ventricular fibrillation. The DFT was estimated using the Dixon "up-and-down" method. Vernakalant significantly increased atrial ERP compared with vehicle controls (34 ± 8 versus 9 ± 7 msec, respectively) without significantly affecting ventricular ERP or DFT. This is consistent with atrial selective actions and supports the conclusion that vernakalant does not alter the efficacy of electrical defibrillation. |
15,486 | Defective Tbx2-dependent patterning of the atrioventricular canal myocardium causes accessory pathway formation in mice. | Ventricular preexcitation, a feature of Wolff-Parkinson-White syndrome, is caused by accessory myocardial pathways that bypass the annulus fibrosus. This condition increases the risk of atrioventricular tachycardia and, in the presence of atrial fibrillation, sudden death. The developmental mechanisms underlying accessory pathway formation are poorly understood but are thought to primarily involve malformation of the annulus fibrosus. Before birth, slowly conducting atrioventricular myocardium causes a functional atrioventricular activation delay in the absence of the annulus fibrosus. This myocardium remains present after birth, suggesting that the disturbed development of the atrioventricular canal myocardium may mediate the formation of rapidly conducting accessory pathways. Here we show that myocardium-specific inactivation of T-box 2 (Tbx2), a transcription factor essential for atrioventricular canal patterning, leads to the formation of fast-conducting accessory pathways, malformation of the annulus fibrosus, and ventricular preexcitation in mice. The accessory pathways ectopically express proteins required for fast conduction (connexin-40 [Cx40], Cx43, and sodium channel, voltage-gated, type V, α [Scn5a]). Additional inactivation of Cx30.2, a subunit for gap junctions with low conductance expressed in the atrioventricular canal and unaffected by the loss of Tbx2, did not affect the functionality of the accessory pathways. Our results suggest that malformation of the annulus fibrosus and preexcitation arise from the disturbed development of the atrioventricular myocardium. |
15,487 | Anaphylactic shock due to intravenous amiodarone. | A 24-year-old male patient was admitted to the coronary intensive care unit with atrial fibrillation with rapid ventricular response. He was given amiodarone (Cordarone 150 mg i.v., Sanofi-Aventis) intravenous loading dose of 300 mg in 100 mL dextrose 5% in water (D5W) over 1 hour, followed by a maintenance dose of 900 mg in 500 mL D5W for infusion up to 24 hours. At the emergency department, the patient was conscious and cooperative; his pretreatment arterial blood pressure was 120/80 mm Hg, and the arrhythmic tachycardia was 145 per minute. After intravenous amiodarone loading and half an hour into maintenance infusion, extreme perspiration, hypotension (blood pressure immeasurable), and mild cyanosis developed. The patient was conscious; his auscultation and pulse were normal. He was given physiologic serum and dopamine support. Approximately an hour later, the blood pressure was measurable. Infusion was terminated because of suspicion of an allergic reaction to acetylsalicylic acid or amiodarone. The allergic reaction observed was attributed to acetylsalicylic acid and amiodarone; infusion was resumed when the clinical situation worsened during the maintenance infusion. Once again, the patient was given physiologic serum (2000 mL), dopamine (20 mg/kg per minute), and, additionally, 250 mg of methyprednisolone sodium succinate intravenous, whereby the clinical condition improved within 20 minutes. Anaphylactic shock cases due to amiodarone are rare; it is important to take a history of drug-mediated anaphylaxis before prescribing amiodarone. An addition to a review of the literature regarding treatment of amiodarone-related anaphylactic shock cases had not been reported before. |
15,488 | Left ventricular ejection fraction for the risk stratification of sudden cardiac death: friend or foe? | More than 450000 Americans die suddenly each year from sustained ventricular tachycardia or fibrillation. A correct identification of these patients is crucial for a rational clinical management, because the demonstrated effectiveness of implantable cardioverter-defibrillators (ICD) on the reduction of sudden cardiac death. Basing on the results of multiple clinical trials, left ventricular systolic function, measured as ejection fraction, is currently the only recommended tool to identify patients at higher risk of sudden death that would benefit from a prophylactic ICD. However, the systematic implementation of prophylactic ICD recommendations results in a substantial number of inappropriate ICD implantations, while failing to prevent the majority of sudden deaths occurring in the general population. That has been the case implementing arrhythmic risk stratification with a rough arrhythmic risk marker, such as ejection fraction, that lacks sensitivity and specificity in the prediction of sudden cardiac death. The aim of this viewpoint is to critically revise the value of ejection fraction in the identification of patients at risk of sudden cardiac death. |
15,489 | Shen-fu injection attenuates postresuscitation myocardial dysfunction in a porcine model of cardiac arrest. | To investigate the effect of Shen-Fu injection (SFI) for the management of postresuscitation myocardial dysfunction in a porcine model of cardiac arrest. Ventricular fibrillation was induced electrically in anesthetized domestic swine. After 4 min of untreated ventricular fibrillation, cardiopulmonary resuscitation was initiated. Sixteen successfully resuscitated pigs were randomized to receive a continuous infusion of either SFI (0.24 mg/min) or saline placebo for 6 h, beginning 15 min after return of spontaneous circulation (ROSC). The SFI treatment produced better left ventricular +dP/dtmax, -dP/dtmax, cardiac output, and ejection fraction after ROSC. The SFI treatment also produced lower serum cardiac troponin I, lactate levels, and left ventricle malondialdehyde content after ROSC, whereas left ventricle superoxide dismutase, Na-K-ATPase, and Ca-ATPase activity were significantly increased in the SFI group when compared with saline group. The cardioprotective effect of SFI was further confirmed by myocardial ultrastructure examination. Shen-Fu injection can attenuate postresuscitation myocardial dysfunction through beneficial effects on energy metabolism and remarkable antioxidant capacity. |
15,490 | Sinus rhythm restoration and treatment success: insight from recent clinical trials. | Atrial fibrillation (AF) is a common supraventricular tachyarrhythmia with substantial morbidity and mortality. This review briefly describes the mechanisms of AF development and progression, including electrical, structural, and contractile remodeling. In addition, the potential benefits of achieving and maintaining sinus rhythm are discussed. For example, rhythm control has been associated with improvements in left ventricular function, AF symptoms, exercise tolerance, the ability to perform activities of daily living, and quality of life. More recently, dronedarone, a noniodinated benzofuran derivative approved for use in the treatment of AF, was shown to significantly improve clinical outcomes including cardiovascular hospitalizations and death from any cause in A Placebo-Controlled, Double-Blind, Parallel Arm Trial to Assess the Efficacy of Dronedarone 400 mg bid for the Prevention of Cardiovascular Hospitalization or Death From Any Cause in Patients With Atrial Fibrillation/Atrial Flutter (ATHENA). The review concludes with an examination of AF treatment options and expectations. Evidence suggests that the complete absence of AF recurrence is not always achievable; however, complete restoration of sinus rhythm may not be necessary for patients to achieve clinically meaningful benefits. Copyright © 2011 Wiley Periodicals, Inc. The editorial assistance provided for this manuscript was funded by Sanofi-Aventis. The authors were fully responsible for all content and editorial decision, and received no financial support or other form of compensation related to the development of the paper. The authors have no other funding, financial relationships, or conflicts of interest to disclose. |
15,491 | Zinc and copper levels in severe heart failure and the effects of atrial fibrillation on the zinc and copper status. | Oxidative stress is involved in the pathogenesis of congestive heart failure (CHF). Some trace elements serve as antioxidant defenses. The purpose of this study was to analyze the effect of atrial fibrillation (AF) on zinc (Zn) and copper (Cu) levels in patients with advanced CHF. In this prospective study, serum Zn and Cu levels in 78 patients with clinically advanced CHF, i.e., New York Heart Association (NYHA) functional class III or IV (40 patients with AF and 38 in sinus rhythm) were measured using atomic absorption spectrophotometry. All patients also had a left ventricular ejection fraction (EF) of <35%. We recruited 40 volunteers with nearly the same age and weight as control. They had normal EF. There was no significant difference between patients with AF and those with sinus rhythm regarding serum Zn and Cu levels. However, both groups showed significant hypozincemia (p < 0.000) and a decreased Zn/Cu ratio (p < 0.03) compared with control group. Serum Cu levels were similar in the two groups and did not differ significantly from the control group. In patients with advanced CHF, irrespective of the rhythm, profound hypozincemia, and a decreased Zn/Cu ratio were present, which could be secondary to the activation of the renin-angiotensin-aldosterone system and CHF medications. The results suggest the need for more studies focusing on possible benefits with Zn nutriceutical replacement in patients with advanced CHF. |
15,492 | Electrophysiological and pharmacological characteristics of triggered activity elicited in guinea-pig pulmonary vein myocardium. | The pulmonary vein is known as an important source of ectopic beats, initiating frequent paroxysms of atrial fibrillation. We analyzed electrophysiological and pharmacological characteristics of triggered activity elicited in the isolated pulmonary vein from the guinea pig. Immediately after the termination of train stimulation (pacing cycle length of 100 ms), spontaneous activities accompanied with phase-4 depolarization were detected in 43 out of 45 pulmonary vein preparations. Such triggered activities were not observed in the isolated left atrium. The incidence of triggered activity was higher at a shorter pacing cycle length (100 - 200 ms), and the coupling interval was shorter at a shorter pacing cycle length. Verapamil (1 µM), ryanodine (0.1 µM), and pilsicainide (10 µM) suppressed the occurrence of triggered activities. The resting membrane potential of the pulmonary vein myocardium was more positive than that of the left atrium. Carbachol (0.3 µM) hyperpolarized the resting membrane potential and completely inhibited the occurrence of triggered activities. These results suggest that the pulmonary veins have more arrhythmogenic features than the left atrium, possibly through lower resting membrane potential. The electrophysiological and pharmacological characteristics of triggered activity elicited in the pulmonary vein myocardium were similar to those previously reported using ventricular tissues. |
15,493 | Functional mathematical model of dual pathway AV nodal conduction. | Dual atrioventricular (AV) nodal pathway physiology is described as two different wave fronts that propagate from the atria to the His bundle: one with a longer effective refractory period [fast pathway (FP)] and a second with a shorter effective refractory period [slow pathway (SP)]. By using His electrogram alternance, we have developed a mathematical model of AV conduction that incorporates dual AV nodal pathway physiology. Experiments were performed on five rabbit atrial-AV nodal preparations to develop and test the presented model. His electrogram alternances from the inferior margin of the His bundle were used to identify fast and slow wave front propagations. The ability to predict AV conduction time and the interaction between FP and SP wave fronts have been analyzed during regular and irregular atrial rhythms (e.g., atrial fibrillation). In addition, the role of dual AV nodal pathway wave fronts in the generation of Wenckebach periodicities has been illustrated. Finally, AV node ablative modifications have been evaluated. The model accurately reproduced interactions between FP and SP during regular and irregular atrial pacing protocols. In all experiments, specificity and sensitivity higher than 85% were obtained in the prediction of the pathway responsible for conduction. It has been shown that, during atrial fibrillation, the SP ablation significantly increased the mean HH interval (204 ± 39 vs. 274 ± 50 ms, P < 0.05), whereas FP ablation did not produce significant slowing of ventricular rate. The presented mathematical model can help in understanding some of the intriguing AV node mechanisms and should be considered as a step forward in the studies of AV nodal conduction. |
15,494 | Comparative bioavailability of a premixed, ready-to-use formulation of intravenous amiodarone with traditional admixture in healthy subjects. | Intravenous amiodarone is an effective agent for the treatment of recurrent ventricular fibrillation and hemodynamically unstable ventricular tachycardia. PM101 Premixed Injection is a new formulation of intravenous amiodarone that uses a cyclodextrin to maintain amiodarone in the aqueous phase. Eighty-eight subjects were enrolled in this randomized, single-blind, crossover, bioequivalence clinical study and were treated with single doses (150 mg) of PM101 Premixed Injection and intravenous amiodarone separated by a washout period of at least 42 days. Venous blood samples were taken periodically during the first 72 hours after dosing to determine standard pharmacokinetic parameters. The geometric ratio of the area under the concentration-time curve for time 0-72 hours (AUC0-72hr ) for amiodarone was 0.96 (95% confidence interval [CI], 0.94-0.99). The geometric ratio of the maximum concentration (Cmax ) for amiodarone was 0.87 (95% CI, 0.84-0.91). Because these ratios and their CI fell between the limits of 0.8 and 1.25, bioequivalence of these 2 formulations was established. No safety concerns unique to the PM101 Premixed Injection, ready-to-use formulation were identified. |
15,495 | Effect of elevated left ventricular diastolic filling pressure on the frequency of left atrial appendage thrombus in patients with nonvalvular atrial fibrillation. | We investigated the relation between left ventricular diastolic dysfunction and left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF). We performed transesophageal echocardiography to examine LAA thrombus or spontaneous echo contrast (SEC) and to measure LAA emptying flow velocity in consecutive 376 patients with AF. We estimated diastolic filling pressure as the ratio of early transmitral flow velocity (E) to mitral annular velocity (e') on transthoracic echocardiogram. E/e' ratio in 28 patients (7.4%) with LAA thrombi was higher than that in patients without thrombus (18.3 ± 9.3 vs 11.4 ± 5.9, p <0.0001). The fourth quartile of E/e' (>13.6) consisted of 19 patients with thrombi and had a higher prevalence of thrombi than the others (p <0.0001). Multivariate regression analysis selected E/e' ≥13 as an independent predictor of LAA thrombus with an odds ratio of 3.50 (1.22 to 10.61) in addition to LA dimension and ejection fraction. Increased quartile of E/e' was negatively associated with LAA flow velocity and positively with rate of SEC. In conclusion, increased diastolic filling pressure is associated with a higher rate of LAA thrombus in AF, partly through blood stasis or impaired LAA function. |
15,496 | New epicardial mapping electrode with warming/cooling function for experimental electrophysiology studies. | Cardiac electrical activity is influenced by temperature. In experimental models, the induction of hypothermia and/or hyperthermia has been used for the study of mechanisms of cardiac arrhythmia. A system that allows for localized, controlled induction, besides simultaneously recording electrical activity in the same induced area, needs to be developed ad hoc. This article describes the construction and application of a new system capable of locally modifying the epicardial temperature of isolated hearts and of carrying out cardiac mapping with sufficient spatial resolution. The system is based on a thermoelectric refrigerator and an array of 128 stainless steel unipolar electrodes in encapsulated epoxy of good thermal conductivity. The surface of the electrode is shaped to match the ventricular curvature. The electrode-device was tested on 7 isolated perfused rabbit hearts following the Langendorff technique. Quality recordings were obtained for the left ventricle at temperatures of 37° C, 22° C and 42° C. The effects of temperature were explored in relation to two electrophysiological parameters: the QT interval during sinus rhythm and the VV interval during ventricular fibrillation. The results indicate that this is a suitable method for creating and analyzing electrophysiological heterogeneities induced by temperature in the experimental model. |
15,497 | Potassium-induced cardiac resetting technique for persistent ventricular tachycardia and fibrillation after aortic declamping. | We report a technique of injecting a high concentration of potassium chloride into the aorta root to resolve refractory ventricular tachycardia after aortic declamping, which occurs occasionally in open heart surgeries. Using this technique, normal sinus rhythm can be restored without the need for defibrillation and aortic clamping. |
15,498 | Spinal cord stimulation effects on myocardial ischemia, infarct size, ventricular arrhythmia, and noninvasive electrophysiology in a porcine ischemia-reperfusion model. | Susceptibility to ventricular arrhythmias and sudden cardiac death can be reduced by modulation of autonomic tone. Spinal cord stimulation (SCS) presumably affects autonomic tone and reduces myocardial ischemia.</AbstractText>The purpose of this study was to investigate whether SCS could reduce myocardial ischemia, infarct size, and ventricular arrhythmias as well as repolarization alterations in a porcine ischemia-reperfusion model.</AbstractText>Anesthetized common Landrace pigs were randomized to SCS (n = 10) or sham treatment (n = 10) before, during, and after 45 minutes of coronary occlusion. Area at risk, infarct size, and spontaneous ventricular arrhythmias were analyzed. Continuous three-dimensional vectorcardiograms was recorded and analyzed with respect to ECG intervals, ST-segment, and T-vector and T-vector-loop morphology.</AbstractText>SCS was associated with significantly (P <.04) fewer episodes of nonsustained ventricular tachycardia (NSVT) and sustained ventricular tachycardia (SVT), particularly during mid-left anterior descending artery (LAD) occlusion (SCS vs non-SCS; NSVT, mid- and proximal LAD: 0 vs 22 and 45 vs 72; SVT, mid- and proximal LAD: 3 vs 15 and 5 vs 5). No difference in ventricular fibrillation episodes was observed. The SCS group had significantly less ST elevation (P <.03) but similar area at risk, infarct size, and ratio of infarct size/area at risk. Ischemia induced increases of T(amplitude) and T(area) suggesting increased repolarization gradients, which were significantly reduced by SCS (P <.01 for both).</AbstractText>SCS appears to have an antiarrhythmic effect on spontaneous NSVT and SVT during ischemia-reperfusion in association with a reduction of repolarization alterations. Vectorcardiography signs of myocardial ischemia were reduced by SCS, but this intervention was not accompanied by any effect on infarct size.</AbstractText>Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.</CopyrightInformation> |
15,499 | Atrial fibrillation in pregnancy. | Physiologic changes of pregnancy can predispose women to cardiac arrhythmias. Atrial fibrillation is rare in pregnancy and usually occurs in women with underlying cardiac anomalies.</AbstractText>A young woman at 22 weeks of gestation presented with new-onset atrial fibrillation with rapid ventricular response. Thorough evaluation revealed atrial fibrillation with no underlying cause and ultimately required treatment with electrical cardioversion.</AbstractText>Lone atrial fibrillation in pregnancy requires exclusion of all possible etiologies before diagnosis. Cardioversion is the treatment of choice. Women with persistent atrial fibrillation require anticoagulation and rate control, as well as fetal growth surveillance and antenatal testing.</AbstractText> |
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