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6,800 | Wolff-Parkinson-White syndrome: where is the pathway? | A 31-year old male presented with atrial fibrillation and ventricular preexcitation that was positive in leads V1-V4, negative in lead II, and positive in lead AVR. The patient was cardioverted and invasive electrophysiologic study was performed. Based on the ECG findings, the coronary sinus and its branches were interrogated during orthodromic atrioventricular reentrant tachycardia. The earliest local activation was seen in the true coronary sinus lumen at the bifurcation of the posterolateral branch. Radiofrequency energy application at this area led to loss of preexcitation. When localizing left septal and posterior accessory pathways, ventricular preexcitation that is both negative in II and positive in AVR has been shown in previous studies to be highly sensitive and specific for a subepicardial location. Therefore, investigation of the coronary sinus and its branches may allow for effective ablation without the need for left ventricular access. |
6,801 | Dominant frequency differences in atrial fibrillation patients with and without left ventricular systolic dysfunction. | The aim of this study was to determine the mechanisms of atrial fibrillation (AF) in patients with left ventricular systolic dysfunction (LVSD).</AbstractText>Dominant frequency (DF) spatiotemporal stability was studied in 15 patients with persistent AF (PEAF) and LVSD (Group I), 15 with PEAF without LVSD (Group II), and 10 with paroxysmal AF (PAAF) without LVSD (Group III). Dominant frequencies were analysed at 536 sites at baseline (DF1) and 26 +/- 12 min later (DF2). A DF1-DF2 difference of <or=0.5 Hz was found in 77, 70, and 48% of sites in Groups I, II, and III (P < 0.001). Maximal DF1 and DF2 were recorded at the same site in 12/15, 11/15, and 0/10 patients in Groups I, II, and III, respectively (P < 0.01). Gradient differences: Group I, DFs were higher at left atrium appendage (LAA) than at anterior (A) LA (ALA), pulmonary vein-left atrial junction (PV-LAJ), and posterior (P) LA (PLA) (7.4 +/- 1.1 vs. 6.6 +/- 1 vs. 6.8 +/- 0.8 vs. 6.8 +/- 0.7 Hz, P < 0.05); Group II, no differences; Group III, DF was higher at PV-LAJ than at LAA, AL, and PLA (6 +/- 1.2 vs. 5.3 +/- 1.1 vs. 5.2 +/- 0.9 vs. 5.4 +/- 1.1 Hz, P < 0.05).</AbstractText>Dominant frequency stability supports stable arrhythmia sources as the mechanism of PEAF with (without) LVSD, but not of PAAF.</AbstractText> |
6,802 | A genotype-dependent intermediate ECG phenotype in patients with persistent lone atrial fibrillation genotype ECG-phenotype correlation in atrial fibrillation. | Atrial fibrillation (AF) is heterogeneous at the clinical and molecular levels. Association studies have reported that common single-nucleotide polymorphisms in KCNE1 and SCN5A may predispose to AF. In this study, we tested the hypothesis that specific AF-associated genotypes confer variation on the appearance of AF assessed by analysis of fibrillatory rate of the atria.</AbstractText>Twenty-six nonrelated patients (21 males, mean age 55+/-12 years) with persistent lone AF (median AF duration 5 weeks) not taking class I or III antiarrhythmic drugs were studied. Fibrillatory rate was obtained by spatiotemporal QRST cancellation and time-frequency analysis of the index surface ECG. Genotypes at the AF-associated loci in KCNE1 (S38G) and SCN5A (H558R) were determined by direct DNA sequencing. The atrial fibrillatory rate was 418+/-50 fibrillations per minute (range, 336 to 521) in the study cohort. Carriers of the 38GG KCNE1 genotype (n=13) had significantly lower fibrillatory rates (392+/-36 versus 443+/-49 fibrillations per minute, P0.006) compared to those with GS or SS genotype (n=13). Six patients (23%) with fibrillatory rates >450 fibrillations per minute, all had either the GS or SS genotype (Chi2 P0.008). In contrast, both the heterozygeous and homozygeous SCN5A H558R polymorphism had no effect on fibrillatory rate. There were no significant associations between fibrillatory rate and clinical (age, gender, AF duration, drug treatment) or echocardiographic (left atrial diameter, left ventricular ejection fraction) variables. In multivariable regression analysis, the KCNE1 S38G genotype (SS/GS coded 0, GG coded 1) was the only independent predictor of fibrillatory rate (beta = -0.437, P = 0.006) with a SE of the estimate of 44 fibrillations per minute.</AbstractText>This study suggests that atrial fibrillatory rate obtained from the surface ECG is at least in part determined by KCNE1 (S38G) genotype, implying that this variant exerts functional effects on atrial electrophysiology. This intermediate ECG phenotype may be useful for elaborating genetic influences on AF mechanisms and identifying subsets of patients for variability in AF susceptibility or response to therapies.</AbstractText> |
6,803 | The utility of 12-lead Holter monitoring in patients with permanent atrial fibrillation for the identification of nonresponders after cardiac resynchronization therapy. | This study sought to determine the incidence of ineffective capture using 12-lead Holter monitoring and to assess whether this affects response to cardiac resynchronization therapy (CRT).</AbstractText>Cardiac resynchronization therapy is used in patients with atrial fibrillation (AF), prolonged QRS duration, and heart failure in the setting of ventricular dysfunction. The percentage of ventricular pacing is used as an indicator of adequate biventricular (BiV) pacing. Although device counters show a high pacing percentage, there may be ineffective capture because of underlying fusion and pseudo-fusion beats.</AbstractText>We identified 19 patients (age 72 +/- 8 years, ejection fraction 18 +/- 5%), with permanent AF who underwent CRT. All patients received digoxin, beta-blockers, and amiodarone for rate control; device interrogation showed >90% BiV pacing. Patients had a 12-lead Holter monitor to assess the presence of effective (>90% fully paced beats/24 h) pacing. At 12 months post-CRT, the New York Heart Association functional class was reassessed and an echocardiogram was obtained and compared with pre-CRT.</AbstractText>Only 9 (47%) patients had effective pacing. The other 10 (53%) patients had 16.4 +/- 4.6% fusion and 23.5 +/- 8.7% pseudo-fusion beats. Long-term responders (> or =1 New York Heart Association functional class improvement) to CRT had a significantly higher percentage of fully paced beats (86.4 +/- 17.1% vs. 66.8 +/- 19.1%; p = 0.03) than nonresponders.</AbstractText>Pacing counters overestimate the degree of effective BiV pacing in patients with permanent AF undergoing CRT therapy. Only patients with complete capture responded clinically to CRT. These findings have important implications for the application of CRT to patients with permanent AF and heart failure.</AbstractText> |
6,804 | Robotic catheter ablation of ventricular tachycardia in a patient with congenital heart disease and Rastelli repair. | Robotically assisted catheter ablation has been proven feasible in patients with a variety of atrial arrhythmias. The potential to provide improved catheter tip maneuvering and stability potentially makes it ideal for complex ablation procedures. We present the case of a patient with complex congenital heart disease with previous Rastelli repair and recurrent ventricular tachycardia (VT) who underwent robotically assisted mapping and ablation for right ventricular VT, utilizing substrate mapping techniques. |
6,805 | Ranolazine exerts potent effects on atrial electrical properties and abbreviates atrial fibrillation duration in the intact porcine heart. | In vitro studies and ambulatory ECG recordings from the MERLIN TIMI-36 clinical trial suggest that the novel antianginal agent ranolazine may have the potential to suppress atrial arrhythmias. However, there are no reports of effects of ranolazine on atrial electrophysiologic properties in large intact animals.</AbstractText>In 12 closed-chest anesthetized pigs, effects of intravenous ranolazine (approximately 9 microM plasma concentration) on multisite atrial effective refractory period (ERP), conduction time (CT), and duration and inducibility of atrial fibrillation (AF) initiated by intrapericardial acetylcholine were investigated. Ranolazine increased ERP by a median of 45 ms (interquartile range 29-50 ms; P < 0.05, n = 6) in right and left atria compared to control at pacing cycle length (PCL) of 400 ms. However, ERP increased by only 28 (24-34) ms in right ventricle (P < 0.01, n = 6). Ranolazine increased atrial CT from 89 (71-109) ms to 98 (86-121) ms (P = 0.04, n = 6) at PCL of 400 ms. Ranolazine decreased AF duration from 894 (811-1220) seconds to 621 (549-761) seconds (P = 0.03, n = 6). AF was reinducible in 1 of 6 animals after termination with ranolazine compared with all 6 animals during control period (P = 0.07). Dominant frequency (DF) of AF was reduced by ranolazine in left atrium from 11.7 (10.7-20.5) Hz to 7.6 (2.9-8.8) Hz (P = 0.02, n = 6).</AbstractText>Ranolazine, at therapeutic doses, increased atrial ERP to greater extent than ventricular ERP and prolonged atrial CT in a frequency-dependent manner in the porcine heart. AF duration and DF were also reduced by ranolazine. Potential role of ranolazine in AF management merits further investigation.</AbstractText> |
6,806 | Potent antiarrhythmic effects of chronic amiodarone in canine pulmonary vein sleeve preparations. | To examine the effects of chronic amiodarone on the electrophysiology of canine pulmonary vein (PV) sleeve preparations and left ventricular wedge preparation.</AbstractText>Amiodarone is commonly used for the treatment of ventricular and supraventricular arrhythmias. Ectopic activity arising from the PV plays a prominent role in the development of atrial fibrillation (AF).</AbstractText>Standard microelectrode techniques were used to evaluate the electrophysiological characteristics of superfused PV sleeve (left superior or inferior) and arterially perfused left ventricular (LV) wedge preparations isolated from untreated and chronic amiodarone-treated dogs (amiodarone, 40 mg/kg daily for 6 weeks).</AbstractText>In PV sleeves, chronic amiodarone (n = 6) induced a significant increase in action potential duration at 90% repolarization (APD90) and a significant use-dependent reduction in Vmax leading to 1:1 activation failure at long cycle lengths (basic cycle length of 124 +/- 15 ms in control vs 420 +/- 320 ms after chronic amiodarone [P < 0.01]). Diastolic threshold of excitation increased from 0.3 +/- 0.2 to 1.8 +/- 0.7 mA (P < 0.01). Delayed and late phase 3 early afterdepolarizations and triggered activity could be induced in PV sleeve preparations using acetylcholine (ACh, 1 microM), high calcium ([Ca2+]o = 5.4 mM), isoproterenol (Iso, 1 microM), or their combination in 6 of 6 untreated PV sleeves, but in only 1 of 5 chronic amiodarone-treated PV sleeve preparations. Vmax, conduction velocity, and 1:1 activation failure were much more affected in PV sleeves versus LV wedge preparations isolated from amiodarone-treated animals.</AbstractText>The results point to potent effects of chronic amiodarone to preferentially suppress arrhythmogenic substrates and triggers arising from the PV sleeves of the dog.</AbstractText> |
6,807 | [A case of acalcuous cholecystitis developed after cardiopulmonary resuscitation]. | A 47-year-old man was found at his home in a state of cardiopulmonary arrest. His family performed cardiopulmonary resuscitation on him. He was brought to our hospital by ambulance. On arrival, his pupils were dilated and his heart was in a state of ventricular fibrillation. After returning to spontaneous circulation by the cardiopulmonary resuscitation, the electrocardiogram revealed ST elevation at V2-V5. Cardiac catheterizatin revealed a left anterior descending coronary obstruction. Percutaneous coronary angioplasty was performed. On the 26th day after admission, acalculous cholecystitis was found. It was difficult to perform emergent surgery, because the patient was taking an anticoagulant drug. We performed PTGBA (percutaneous transhepatic gallbladder aspiration) on the same day, and the gallbladder inflammation was improved. We consider that PTGBA is an effective treatment for difficult cases of acalcuous cholecystitis. |
6,808 | When should serum magnesium be measured prior to non-cardiac surgery? | While prospective data is scant, the advisability of magnesium measurement appears to be convincing in selected circumstances. Electrolyte abnormalities, mainly hypokalemia and hypomagnesemia, are associated with an increased risk for developing cardiac arrhythmias, however, conflicting opinions remain. If performed on all patients undergoing non-cardiac surgery, magnesium measurement would add considerably to health care costs; however, if limited to patients identified as high risk by the above parameters, the additional cost per patient is in keeping with other standard tests. Given the low cost of testing and replacement, preoperative magnesium measurement appears reasonable in patients with structural heart disease, diabetes, chronic alcoholism, and chronic (loop) diuretic use. When high risk patients are undergoing high risk operations, the low cost of measurement and replacement appears particularly cost-effective, whether it reduces morbidity and prolonged hospitalization from atrial fibrillation or mortality from sustained ventricular arrhythmias. Until additional data becomes available, use of this simple test in patients likely to manifest hypomagnesemia who are at elevated risk of cardiac tachyarrhythmias and cardiac complications following non-cardiac surgery seems prudent. |
6,809 | Guideline for resuscitation in cardiac arrest after cardiac surgery. | The Clinical Guidelines Committee of the European Association for Cardio-Thoracic Surgery provides this professional view on resuscitation in cardiac arrest after cardiac surgery. This document was created using a multimodal methodology for evidence generation including the extrapolation of existing guidelines from the International Liaison Committee on Resuscitation where possible, our own structured literature reviews on issues particular to cardiac surgery, an international survey on resuscitation hosted by CTSNet and manikin simulations of potential protocols. This protocol differs from existing generic guidelines in a number of areas, the most import of which are the following: successful treatment of cardiac arrest after cardiac surgery is a multi-practitioner activity with six key roles that should be allocated and rehearsed on a regular basis; in ventricular fibrillation, three sequential attempts at defibrillation (where immediately available) should precede external cardiac massage; in asystole or extreme bradycardia, pacing (where immediately available) should precede external cardiac massage; where the above measures fail, and in pulseless electrical activity, early resternotomy is advocated; adrenaline should not be routinely given; protocols for excluding reversible airway and breathing complications and for safe emergency resternotomy are given. This guideline is subject to continuous informal review, and when new evidence becomes available. |
6,810 | Ca2+: is there something new for the cardiovascular anesthesiologist? | Anesthesiologists are frequently called upon to treat abnormalities of heart rhythm or pumping ability. Intracellular Ca is crucial for normal excitation-contraction coupling in the heart and plays a major role in the sequence of events that starts with an electrical signal generated in the atria and ends with myocardial contraction.</AbstractText>From controlled diffusion within the cell to a potential role as a biological clock, intracellular Ca is receiving a great deal of attention. For example, the pacemaking electrical signal is known to originate in the sinoatrial node myocyte, but exactly what role Ca plays is controversial despite the fact that the sinoatrial node was discovered over 100 years ago. Basic mechanisms involved in disease processes such as atrial fibrillation and new interventions for heart rate control are beginning to emerge. New discoveries in ventricular myocytes are also stimulating the development of promising therapeutic interventions to safely increase the pumping ability of the heart.</AbstractText>As our understanding of cardiac physiology and pharmacology progresses at the subcellular and molecular levels, new therapies will continue to emerge and the practice of anesthesia will benefit greatly.</AbstractText> |
6,811 | [Brugada syndrome--underestimated cause of sudden cardiac death in patients without an organic cardiac disease--a case report]. | We present a case of a 61-year-old man with a history of syncope and sudden cardiac arrest due to ventricular fibrillation, with the symptoms of spontaneous electrocardiographic changes characteristic for the Brugada syndrome. The patient received an implantable cardioverter-defibrillator. This patient was previously hospitalised in 2003, when the diagnosis of atrio-ventricular block has been established and in 2006, when he had chest pain and was operated because of the right coronary artery ostium haematoma. However, the diagnosis of Brugada syndrome was not established. |
6,812 | Mechanical cardiac remodeling and new-onset atrial fibrillation in long-term follow-up of subjects with chronic Chagas' disease. | Atrial fibrillation (AF) affects subjects with Chagas' disease and is an indicator of poor prognosis. We investigated clinical, echocardiographic and electrocardiographic variables of Chagas' disease in a long-term longitudinal study as predictors of a new-onset AF episode lasting >24 h, nonfatal embolic stroke and cardiac death. Fifty adult outpatients (34 to 74 years old, 62% females) staged according to the Los Andes classification were enrolled. During a follow-up of (mean +/- SD) 84.2 +/- 39.0 months, 9 subjects developed AF (incidence: 3.3 +/- 1.0%/year), 5 had nonfatal stroke (incidence: 1.3 +/- 1.0%/year), and nine died (mortality rate: 2.3 +/- 0.8%/year). The progression rate of left ventricular mass and left ventricular ejection fraction was significantly greater in subjects who experienced AF (16.4 +/- 20.0 g/year and -8.6 +/- 7.6%/year, respectively) than in those who did not (8.2 +/- 8.4 g/year; P = 0.03, and -3.0 +/- 2.5%/year; P = 0.04, respectively). In univariate analysis, left atrial diameter >/=3.2 cm (P = 0.002), pulmonary arterial hypertension (P = 0.035), frequent premature supraventricular and ventricular contraction counts/24 h (P = 0.005 and P = 0.007, respectively), ventricular couplets/24 h (P = 0.002), and ventricular tachycardia (P = 0.004) were long-term predictors of AF. P-wave signal-averaged ECG revealed a limited long-term predictive value for AF. In chronic Chagas' disease, large left atrial diameter, pulmonary arterial hypertension, frequent supraventricular and ventricular premature beats, and ventricular tachycardia are long-term predictors of AF. The rate of left ventricular mass enlargement and systolic function deterioration impact AF incidence in this population. |
6,813 | Recognition and management of complex rhythm disorders in heterotopic heart transplantation. | Managing arrhythmias is challenging in patients who have undergone heterotopic heart transplantation because of the superimposed rhythms of the native and donor hearts. We present the case of a 43-year-old man with a previously placed biventricular pacemaker who underwent heterotopic heart transplantation and later developed acute rejection of the donor heart, which led to bradycardia and pause-dependent ventricular fibrillation. The patient remained clinically stable in the short term, likely because of partial recovery of myocardial function in the native heart. He later underwent placement of a pacing lead in the donor heart, allowing linking of the two hearts via a biventricular pacemaker. |
6,814 | Haplotype-sharing analysis implicates chromosome 7q36 harboring DPP6 in familial idiopathic ventricular fibrillation. | Idiopathic Ventricular Fibrillation (IVF) is defined as spontaneous VF without any known structural or electrical heart disease. A family history is present in up to 20% of probands with the disorder, suggesting that at least a subset of IVF is hereditary. A genome-wide haplotype-sharing analysis was performed for identification of the responsible gene in three distantly related families in which multiple individuals died suddenly or were successfully resuscitated at young age. We identified a haplotype, on chromosome 7q36, that was conserved in these three families and was also shared by 7 of 42 independent IVF patients. The shared chromosomal segment harbors part of the DPP6 gene, which encodes a putative component of the transient outward current in the heart. We demonstrated a 20-fold increase in DPP6 mRNA levels in the myocardium of carriers as compared to controls. Clinical evaluation of 84 risk-haplotype carriers and 71 noncarriers revealed no ECG or structural parameters indicative of cardiac disease. Penetrance of IVF was high; 50% of risk-haplotype carriers experienced (aborted) sudden cardiac death before the age of 58 years. We propose DPP6 as a gene for IVF and increased DPP6 expression as the likely pathogenetic mechanism. |
6,815 | Ventricular fibrillation in acute mitral valve insufficiency caused by chordae tendineae rupture: report of a surgically corrected case. | In this report, we present the case of a previously healthy 80-year-old woman who was referred to surgery after a cardiac arrest due to ventricular fibrillation successfully resuscitated; the following evaluation revealed acute mitral regurgitation due to chordae tendineae rupture. After mitral valve repair, a single-chamber cardioverter-defibrillator was implanted for secondary prevention of sudden cardiac death. After 16 months of follow-up, the patient is asymptomatic without any further episodes of ventricular arrhythmias reported, underlying the pivotal role of mitral valve repair in the prevention of potentially lethal ventricular arrhythmias. |
6,816 | A randomised, controlled study of rate versus rhythm control in patients with chronic atrial fibrillation and heart failure: (CAFE-II Study). | Atrial fibrillation (AF) and heart failure (HF) often coexist. The aim was to investigate whether restoring sinus rhythm (SR) could improve cardiac function, symptoms, exercise capacity and quality of life (QoL) in patients with chronic heart failure.</AbstractText>Patients with HF and persistent AF receiving guideline-recommended treatments, including anticoagulants, were eligible for the study. Patients were randomised to either rhythm (treated with amiodarone for at least 3 months prior to attempting biphasic external cardioversion and continued amiodarone long-term if SR was restored) or rate control. Anticoagulants were continued throughout the study regardless of rhythm, unless contraindications developed. Both groups were treated with beta blockers and/or digoxin to reduce the heart rate to <80 bpm at rest and <110 bpm after walking. Symptoms, walk distance (6-minute corridor walk test, 6MWT), QoL and cardiac function were assessed at baseline and 1 year.</AbstractText>61 patients with HF and persistent AF (median duration 14 months (IQR 5 to 32)) were randomly assigned to a rate or rhythm control strategy. Of patients assigned to rhythm control (n = 30), 66% were in SR at 1 year, and 90% of those assigned to rate control (n = 31) achieved the heart rate target. At 1 year, NYHA class (p = 0.424) and 6MWT distance (p = 0.342) were similar between groups but patients assigned to rhythm control had improved LV function (p = 0.014), NT-proBNP concentration (p = 0.046) and QoL (p = 0.019) compared with those assigned to rate control. Greatest improvement was seen in patients in whom SR was maintained.</AbstractText>Restoring SR in patients with AF and heart failure may improve QoL and LV function when compared with a strategy of rate control.</AbstractText> |
6,817 | Heart failure with normal left ventricular ejection fraction. | It is estimated that approximately 50% of the heart failure population has a normal left ventricular ejection fraction, a complex broadly referred to as heart failure with normal left ventricular ejection fraction (HFNEF). While these patients have been considered in epidemiologic studies and clinical trials to represent a single pool of patients, limited more detailed studies indicate that HFNEF patients are a very heterogeneous group, with a number of key pathophysiologic mechanisms. This review summarizes and critically analyzes available data on the pathophysiology of HFNEF, placing it into context with a recently developed diagnostic algorithm. We evaluate the utility of commonly applied echocardiographic measures and biomarkers and integrate mechanistic observations into potential future therapeutic directions. |
6,818 | Micro-electrocardiograms to study post-ventricular amputation of zebrafish heart. | The zebrafish (Danio rerio) is an emerging model for cardiovascular research. The zebrafish heart regenerates after 20% ventricular amputation. However, assessment of the physiological responses during heart regeneration has been hampered by the small size of the heart and the necessity of conducting experiments in an aqueous environment. We developed a methodology to monitor a real-time surface electrocardiogram (ECG) by the use of micro-electrodes, signal amplification, and a low pass-filter at a sampling rate of 1 kHz. Wavelet transform was used to further remove ambient noises. Rather than paralyzing the fish, we performed mild sedation by placing the fish in a water bath mixed with MS-222 (tricane methanesulfonate). We recorded distinct P waves for atrial contraction, QRS complexes for ventricular depolarization, and QT intervals for ventricular repolarization prior to, and 2 and 4 days post-amputation (dpa). Sedation reduced the mean fish heart rate from 149 +/- 18 to 90 +/- 17 beats/min. The PR and QRS intervals remained unchanged in response to ventricular apical amputation (n = 6, p > 0.05). Corrected QT intervals (QTc) were shortened 4 dpa (n = 6, p < 0.05). In a parallel study, histology revealed that apical thrombi were replaced with fibrin clots and collagen fibers. Atrial arrhythmia was noted in response to prolonged sedation. Unlike the human counterpart, ventricular tachycardia or fibrillation was not observed in response to ventricular amputation 2 and 4 dpa. Taken together, we demonstrated a minimally invasive methodology to monitor zebrafish heart function, electrical activities, and regeneration in real-time. |
6,819 | Predictors of early mortality in implantable cardioverter-defibrillator recipients. | Multiple trials have shown that implantable cardioverter defibrillators (ICDs) prolong survival in secondary and primary prevention populations. However, in spite of the efficacy of these devices in terminating life-threatening arrhythmias, total mortality remains high.</AbstractText>We evaluated 1703 patients (mean age: 67 +/- 12 years, 82% male) with conventional ICD indications, who were enrolled and followed between 2001 and 2004 at 128 US centres. Patients were followed for up to a year, and vital status was obtained for 1655 patients (97%, median follow-up: 377 days). There were 183 deaths within 1 year of ICD implantation (1-year mortality rate: 16%). Predictors of mortality included a history of atrial fibrillation (AF, P < 0.0001), diabetes (P = 0.0001), failure to use cholesterol-lowering medications (P < 0.001), use of digitalis and derivatives (P < 0.0001), use of diuretics (P < 0.0001), low body mass index (BMI, P < 0.0001), increasing age (P < 0.0001), low left ventricular ejection fraction (P < 0.0001), low activity hours (P < 0.0001), elevated resting heart rate (P = 0.014), low mean arterial pressure (MAP, P = 0.007), and poor functional status (New York Heart Association class, P < 0.0001). In multivariate modelling, AF (P < or = 0.001), diabetes (P = 0.004), BMI (P = 0.001), MAP (P = 0.040), and functional class (P = 0.006) predicted mortality.</AbstractText>In this population undergoing ICD implantation, poor functional status, low MAP, diabetes, low BMI, and AF were strongly associated with death within a year.</AbstractText> |
6,820 | Pharmacological therapy for atrial fibrillation: current options and new agents. | Atrial fibrillation is the most commonly encountered cardiac arrhythmia and is directly or indirectly responsible for considerable mortality, morbidity and health care burden. The available medical therapy is limited by marginal efficacy, end-organ toxicity, as well as the potential for undesired ventricular proarrhythmia. Elucidation of the potential mechanisms that underlie the development of atrial fibrillation may provide new targets for drugs that circumvent the problems associated with current medical options. This review focuses on the current and potential future pharmacological agents directed at rhythm control and maintenance of sinus rhythm. |
6,821 | Epidemiology and outcomes from out-of-hospital cardiac arrest in children: the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest. | Population-based data for pediatric cardiac arrest are scant and largely from urban areas. The Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac Arrest is a population-based emergency medical services registry of out-of-hospital nontraumatic cardiac arrest (OHCA). This study examined age-stratified incidence and outcomes of pediatric OHCA. We hypothesized that survival to hospital discharge is less frequent from pediatric OHCA than adult OHCA.</AbstractText>This prospective population-based cohort study in 11 US and Canadian ROC sites included persons <20 years of age who received cardiopulmonary resuscitation or defibrillation by emergency medical service providers and/or received bystander automatic external defibrillator shock or who were pulseless but received no resuscitation by emergency medical services between December 2005 and March 2007. Patients were stratified a priori into 3 age groups: <1 year (infants; n=277), 1 to 11 years (children; n=154), and 12 to 19 years (adolescents; n=193). The incidence of pediatric OHCA was 8.04 per 100 000 person-years (72.71 in infants, 3.73 in children, and 6.37 in adolescents) versus 126.52 per 100,000 person-years for adults. Survival for all pediatric OHCA was 6.4% (3.3% for infants, 9.1% for children, and 8.9% for adolescents) versus 4.5% for adults (P=0.03). Unadjusted odds ratio for pediatric survival to discharge compared with adults was 0.71 (95% confidence interval, 0.37 to 1.39) for infants, 2.11 (95% confidence interval, 1.21 to 3.66) for children, and 2.04 (95% confidence interval, 1.24 to 3.38) for adolescents.</AbstractText>This study demonstrates that the incidence of OHCA in infants approaches that observed in adults but is lower among children and adolescents. Survival to discharge was more common among children and adolescents than infants or adults.</AbstractText> |
6,822 | Poincaré surface profiles of RR intervals: a novel noninvasive method for the evaluation of preferential AV nodal conduction during atrial fibrillation. | The ventricular response during atrial fibrillation (AF) presents particular characteristics that may play a relevant role in the selection of the most appropriate treatment. Using different ECG signal processing techniques such as RR histogram analysis or histographic Poincaré plots (PPs) (so-called 3-D PPs), clusters of RR intervals due to preferential atrioventricular (AV) node conduction can be observed. However, these methods are limited by the need for visual inspection and subjective interpretation of analysis results. The objective of this paper is to develop a method to automatically detect and quantify preferential clusters of RR intervals. This novel method, the Poincaré surface profile (PSP), uses the information of histographic PPs to filter part of the AV node memory effects. PSP detected all RR populations present in RR interval histograms in 55 patients with persistent AF and also 67% additional RR populations. In addition, a reduction of beat-to-beat dependencies allowed a more accurate location of RR populations. This novel Poincaré-plot-based analysis also allows monitoring of short-term variations of preferential conductions. We illustrate the capability of this short-time monitoring technique to evaluate the effects of rate control drugs on each preferential conduction. |
6,823 | Spatiotemporal frequency analysis of ventricular fibrillation in explanted human hearts. | Ventricular fibrillation (VF) is a medical condition that occurs due to rapid and irregular electrical activity of heart. If undiagnosed or untreated, VF leads to sudden cardiac death. VF has been studied by researchers for over 100 years to elucidate the mechanism that maintains VF, and thus to arrive at therapeutic options. VF is a nonstationary process, and it manifests into variations in the waveform morphology, phase, and frequency dynamics of the surface electrograms. Dominant frequency analysis (DF maps) and phase maps are two widely used complementary approaches in assessing the evolution of VF process. These techniques are applied to electrograms or fluorescence signals obtained with voltage-sensitive dyes. In spite of VF being a nonstationary process, most of the existing literature limits frequency analysis to a segmented, time-averaged spectral analysis, where valuable information on the instantaneous temporal evolution of the spectral characteristics is lost. In order to resolve this issue, in this paper, we present a joint time-frequency approach that is suited for VF analysis and demonstrate the application of instantaneous mean frequency (IMF) in interpreting VF episodes. Human VF sources are rarely anatomically stable and are migratory. Traditional DF techniques fail in tracking this migratory behavior. IMF, on the other hand, can deal with these migratory sources and conduction blocks better than DF approaches. Results of the analysis using the electrograms of 204 VF segments obtained from 13 isolated human hearts (explanted during cardiac transplantation) indicate that in 81% of the VF segments, there were significant changes in the spatiotemporal evolution of the frequency, suggesting that IMF provides better mechanistic insight of these signals. The IMF tool presented in this paper demonstrates potential for applications in tracking frequency patterns, conduction blocks, and arriving at newer therapies to modulate VF. |
6,824 | Distinct functional defect of three novel Brugada syndrome related cardiac sodium channel mutations. | The Brugada syndrome is characterized by ST segment elevation in the right precodial leads V1-V3 on surface ECG accompanied by episodes of ventricular fibrillation causing syncope or even sudden death. The molecular and cellular mechanisms that lead to Brugada syndrome are not yet completely understood. However, SCN5A is the most well known responsible gene that causes Brugada syndrome. Until now, more than a hundred mutations in SCN5A responsible for Brugada syndrome have been described. Functional studies of some of the mutations have been performed and show that a reduction of human cardiac sodium current accounts for the pathogenesis of Brugada syndrome. Here we reported three novel SCN5A mutations identified in patients with Brugada syndrome in Taiwan (p.I848fs, p.R965C, and p.1876insM). Their electrophysiological properties were altered by patch clamp analysis. The p.I848fs mutant generated no sodium current. The p.R965C and p.1876insM mutants produced channels with steady state inactivation shifted to a more negative potential (9.4 mV and 8.5 mV respectively), and slower recovery from inactivation. Besides, the steady state activation of p.1876insM was altered and was shifted to a more positive potential (7.69 mV). In conclusion, the SCN5A channel defect related to Brugada syndrome might be diverse but all resulted in a decrease of sodium current. |
6,825 | Unusual cause of recurrent syncope in a child. | A 5-year-old boy with an unremarkable past medical and family history presented with recurrent syncope precipitated by physical activity. Electrocardiogram performed in the emergency room after one of his episodes revealed atrial flutter. He had a structurally normal heart. Exercise stress test revealed atrial fibrillation with rapid ventricular response immediately on commencement of running. Atrial fibrillation subsequently organized into atrial flutter with variable ventricular response followed by spontaneous conversion to sinus rhythm. This case highlights the use of exercise stress test in a preschool child to elicit an unusual cause of syncope. |
6,826 | Ventricular fibrillation triggered during and after radiofrequency energy delivery to the site of origin of idiopathic right ventricular outflow tract arrhythmia. | We observed a case of idiopathic ventricular arrhythmias originating from the right ventricular outflow tract (RVOT). The origin of target premature ventricular contraction (PVC) and nonsustained ventricular tachycardia (VT) was within a wide low-voltage area around the RVOT. During radiofrequency (RF) application to the site of arrhythmia origin, polymorphic VT and ventricular fibrillation were repeatedly triggered by new PVC that had developed near the site of ablation. This electrical storm persisted >30 minutes after cessation of RF current delivery, and was suppressed by additional RF applications to the site of origin of the new PVC. |
6,827 | Excellent long-term reproducibility of the electrophysiologic efficacy of quinidine in patients with idiopathic ventricular fibrillation and Brugada syndrome. | Quinidine is very effective in preventing the reinduction of sustained ventricular fibrillation (VF) during electrophysiologic study (EPS) in patients with idiopathic VF and Brugada syndrome. However, there are no data on the long-term reproducibility of this EP efficacy.</AbstractText>Nine patients (seven males and two females, aged 21-72 years), who suffered from aborted cardiac arrest (n = 8) or recurrent syncope (n = 1) due to Brugada syndrome (n = 5) or idiopathic VF (n = 4), comprised the study. All patients had inducible sustained VF at baseline that was prevented by quinidine therapy and underwent another EPS on medication after 1.7-23.6 (9.8 +/- 6.8) years (>5 years in eight patients). Two patients underwent two late EPS on quinidine. The goal of repeat EPS on quinidine was to ensure persistent long-term drug efficacy (n = 6) or to elucidate the reason of syncopal episodes during therapy (n = 3). The EPS protocol significantly evolved over the years as it became more aggressive (more pacing sites and/or more ventricular extrastimuli). All nine patients tolerated the medication well and had no recurrent documented arrhythmic events during long-term follow-up (mean 15 +/- 7 years). No sustained ventricular tachyarrhythmias could be induced in any patient during repeat late EPS. In six patients, a more aggressive stimulation protocol could be tested at repeat EPS.</AbstractText>The long-term reproducibility of the EP efficacy of quinidine in patients with idiopathic VF and Brugada syndrome is excellent. EP-guided quinidine therapy represents a valuable long-term alternative to ICD therapy in these patients.</AbstractText> |
6,828 | Role of left ventricular scar and Purkinje-like potentials during mapping and ablation of ventricular fibrillation in dilated cardiomyopathy. | Purkinje-like potentials (PLPs) have been described as important contributors to initiation of ventricular fibrillation (VF) in patients with normal hearts, ischemic cardiomyopathy, and early after-myocardial infarction.</AbstractText>Of the 11 consecutive patients with VF storm, nonischemic cardiomyopathy (68 +/- 22 years, left ventricular ejection fraction 28 +/- 8%) who were given antiarrhythmic drugs and/or heart failure management, five had recurrent VF and underwent electrophysiology study (EPS) and catheter ablation.</AbstractText>At EPS, frequent monomorphic premature ventricular contractions (PVC) and/or ventricular tachycardia did not occur. With isoproterenol, VF was induced in three patients, and sustained monomorphic PVCs were induced in one patient. Three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, CA) revealed posterior wall scar in four of the five patients. PLP in sinus rhythm were recorded around the scar border in these four patients, and radiofrequency ablation targeting PLP was successfully performed at these sites. The patient without PLP did not undergo ablation. During follow-up (12 +/- 5 months), only the patient without PLP had four VF recurrences requiring implantable cardioverter-defibrillator (ICD) shocks.</AbstractText>In patients with VF and dilated cardiomyopathy, left ventricular posterior wall scar in the vicinity of the mitral annulus seems to be a common finding. Targeting PLP along the scar border zone for ablation seems to efficiently prevent VF recurrence in these patients.</AbstractText> |
6,829 | Fragmented QRS: a predictor of mortality and sudden cardiac death. | Several invasive and noninvasive tests for risk stratification of sudden cardiac death have been studied, mostly in the context of structural heart disease such as coronary artery disease (CAD), cardiomyopathy, and heart failure. Tests such as MTWA (repolarization abnormality) and SAECG (depolarization abnormality) have high negative predictive values but a low positive predictive value in patients with myocardial infarction or cardiomyopathy. Recently, we described the presence of a fragmented QRS complexes (fQRS) on a routine 12-lead electrocardiogram as another marker of depolarization abnormality. fQRS represents conduction delay caused by myocardial scar in patients with CAD. However, fQRS is not specific for CAD and is also encountered in other myocardial diseases such as cardiomyopathy and congenital heart disease. fQRS is associated with increased mortality and arrhythmic events in patients with CAD. fQRS has also been defined as a marker of arrhythmogenic right ventricular dysplasia/cardiomyopathy and Brugada syndrome. In Brugada syndrome, the presence of fQRS predicts episodes of ventricular fibrillation during follow-up. Therefore, the utility of fQRS in risk stratification of sudden cardiac death needs to be explored further, especially in nonischemic cardiomyopathy and heart failure. |
6,830 | Analysis of 57,148 transmissions by remote monitoring of implantable cardioverter defibrillators. | Remote monitoring of implantable cardioverter defibrillators (ICD) is designed to decrease the number of ambulatory visits and facilitate the early detection of adverse events. We examined the impact of remote monitoring on clinical workload by a comprehensive analysis of transmitted events.</AbstractText>The study population consisted of 146 recipients of ICD capable of remote monitoring. Data were transmitted daily or in case of pre-specified events (e.g., arrhythmia, out-of-range lead and/or shock impedance). Transmitted events were classified as clinical (disease-related) or system-related. Event rates/patient/month were calculated and compared according to events classification and clinical groups.</AbstractText>During a mean follow-up of 22 +/- 16 months, a total of 57,148 remote transmissions were recorded. Of these transmissions, 1009 (1.8%) were triggered by a pre-specified event, including induced ventricular fibrillation (VF) episodes during defibrillation threshold testing. The median number of events/patient/month was 0.14. Event rates were similar in patients with primary and secondary prevention indications for ICD (0.15 vs. 0.11). After exclusion of the induced VF episodes, 5.6% of transmitted events were classified as system-related and 94.4% as clinical. The median number of clinical events/patient/month was 0.023. The clinical event-free rates were 62% and 45%, at 1 and 4 years, respectively.</AbstractText>Remote monitoring of ICD patients is feasible. Despite the large number of data transmissions, remote monitoring imposed a minimal additional burden on the clinical workload. The rate of triggered data transmissions by critical events was, relatively, very low.</AbstractText> |
6,831 | Impact of AV conduction disorders on SafeR mode performance. | CAN-SAVE R is a Canadian multicenter study that compares the effects of a new pacing mode algorithm designed to minimize right ventricular (V) pacing versus DDD mode with a long atrioventricular (AV) delay in a general population of pacemaker (PM) recipients.</AbstractText>Patients with permanent atrial fibrillation (AF) or high-degree AV block (AVB) were excluded. We present preliminary data collected in 208 patients (mean age=71 +/- 11 years, 68% men), for the 2-month baseline period during which all PM were programmed in the new pacing mode. The pacing indications were sinus node disease (SND) without AVB in 39%, AVB without SND in 30%, SND and AVB in 16%, and miscellaneous in 15% of patients.</AbstractText>The mean percent V pacing in the overall population was 9.5 +/- 23.8% (range=0-100%, median <1%), ranging between 0.5 +/- 1.5% (median=0) in patients without AVB and 18.7 +/- 31.2% in patients (median = 1) with AVB. Adverse events potentially related to the new pacing mode were observed in two patients with AVB.</AbstractText>A new pacing mode was effective and safe in a general population of PM recipients without permanent AVB and was associated with an overall <1% median V pacing. CAN-SAVE R will compare the long-term effects of the new pacing mode with DDD with a long AV delay on clinical outcomes and cardiac function.</AbstractText> |
6,832 | Coronary blood flow produced by muscle contractions induced by intracardiac electrical CPR during ventricular fibrillation. | It has been reported that transthoracic electrical cardiopulmonary resuscitation (ECPR) generates coronary perfusion pressures (CPP) similar to manual chest compressions (MCC). We hypothesized that intracardiac ECPR produces similar CPP.</AbstractText>ECPR pulse train protocols were applied for 20 seconds in a porcine model following 10 seconds of ventricular fibrillation (VF), using a defibrillator housing electrode and a right ventricular coil (IC-ECPR). Each protocol consisted of 200-ms electrical pulse trains applied at a rate of 100 pulse trains/min. The protocols were grouped in skeletal-based versus cardiac-based stimulation measurements. CPP was recorded and compared to historical MCC values generated by a similar experimental design. CPP > 15 mm Hg at 30 seconds of VF following the application of an IC-ECPR protocol was defined as successful.</AbstractText>Mean CPP for all intracardiac ECPR pulse train protocols at 30 seconds of VF was 14.8 +/- 3.8 mm Hg (n = 39). Mean CPP in seven successful skeletal-based IC-ECPR protocols was 19.4 +/- 3.2 mm Hg, and mean CPP in 10 successful cardiac-based IC-ECPR protocols was 17.4 +/- 2.1 mm Hg. Reported CPP for 15 MCC experiments at 30 seconds of VF was 22.9 +/- 9.4 mm Hg (P = 0.35 compared to skeletal-based IC-ECPR, P = 0.08 compared to cardiac-based IC-ECPR).</AbstractText>Intracardiac applied electrical CPR produced observable skeletal muscle contractions, measurable pressure pulses, and coronary perfusion pressures similar to MCC during a brief episode of untreated VF.</AbstractText> |
6,833 | Spiral-wave turbulence and its control in the presence of inhomogeneities in four mathematical models of cardiac tissue. | Regular electrical activation waves in cardiac tissue lead to the rhythmic contraction and expansion of the heart that ensures blood supply to the whole body. Irregularities in the propagation of these activation waves can result in cardiac arrhythmias, like ventricular tachycardia (VT) and ventricular fibrillation (VF), which are major causes of death in the industrialised world. Indeed there is growing consensus that spiral or scroll waves of electrical activation in cardiac tissue are associated with VT, whereas, when these waves break to yield spiral- or scroll-wave turbulence, VT develops into life-threatening VF: in the absence of medical intervention, this makes the heart incapable of pumping blood and a patient dies in roughly two-and-a-half minutes after the initiation of VF. Thus studies of spiral- and scroll-wave dynamics in cardiac tissue pose important challenges for in vivo and in vitro experimental studies and for in silico numerical studies of mathematical models for cardiac tissue. A major goal here is to develop low-amplitude defibrillation schemes for the elimination of VT and VF, especially in the presence of inhomogeneities that occur commonly in cardiac tissue. We present a detailed and systematic study of spiral- and scroll-wave turbulence and spatiotemporal chaos in four mathematical models for cardiac tissue, namely, the Panfilov, Luo-Rudy phase 1 (LRI), reduced Priebe-Beuckelmann (RPB) models, and the model of ten Tusscher, Noble, Noble, and Panfilov (TNNP). In particular, we use extensive numerical simulations to elucidate the interaction of spiral and scroll waves in these models with conduction and ionic inhomogeneities; we also examine the suppression of spiral- and scroll-wave turbulence by low-amplitude control pulses. Our central qualitative result is that, in all these models, the dynamics of such spiral waves depends very sensitively on such inhomogeneities. We also study two types of control schemes that have been suggested for the control of spiral turbulence, via low amplitude current pulses, in such mathematical models for cardiac tissue; our investigations here are designed to examine the efficacy of such control schemes in the presence of inhomogeneities. We find that a local pulsing scheme does not suppress spiral turbulence in the presence of inhomogeneities; but a scheme that uses control pulses on a spatially extended mesh is more successful in the elimination of spiral turbulence. We discuss the theoretical and experimental implications of our study that have a direct bearing on defibrillation, the control of life-threatening cardiac arrhythmias such as ventricular fibrillation. |
6,834 | Relationship between left atrial size and stroke in patients with sinus rhythm and preserved systolic function. | <AbstractText Label="BACKGROUND/AIMS" NlmCategory="OBJECTIVE">Increased left atrial (LA) size has been proposed as a predictor of poor cardiovascular outcome in the elderly. In the present study, we evaluated the relationship between LA size and stroke in subjects of all ages who presented with preserved left ventricular systolic function (LVSF) and sinus rhythm (SR), and investigated the relationships between LA size and other echocardiographic parameters of diastolic function.</AbstractText>A total of 472 subjects were enrolled in the study (161 men, 311 women) and divided into the stroke group (n=75) and control group (n=397). A conventional echocardiographic study was then performed. Subjects with valvular heart disease, atrial fibrillation, or coronary heart disease were excluded.</AbstractText>The mean subject age was 65.2+/-5.1 years in the stroke group and 65.6+/-5.9 years in the control group. Mitral inflow pattern and E & A velocity showed no significant relationship with stroke (p=NS, p=NS, respectively). Left ventricular mass index and LA dimension were significantly related to stroke (p=0.003, p=0.023, respectively), and hypertension showed a marginal relationship with stroke (p=0.050). Age was not related to stroke in the present study (p=NS).</AbstractText>The LA dimension is significantly related to the incidence of stroke. Therefore, strategies for prevention of stroke in patients with preserved LVSF and SR should be considered in cases of LA enlargement.</AbstractText> |
6,835 | Towards predictive modelling of the electrophysiology of the heart. | The simulation of cardiac electrical function is an example of a successful integrative multiscale modelling approach that is directly relevant to human disease. Today we stand at the threshold of a new era, in which anatomically detailed, tomographically reconstructed models are being developed that integrate from the ion channel to the electromechanical interactions in the intact heart. Such models hold high promise for interpretation of clinical and physiological measurements, for improving the basic understanding of the mechanisms of dysfunction in disease, such as arrhythmias, myocardial ischaemia and heart failure, and for the development and performance optimization of medical devices. The goal of this article is to present an overview of current state-of-art advances towards predictive computational modelling of the heart as developed recently by the authors of this article. We first outline the methodology for constructing electrophysiological models of the heart. We then provide three examples that demonstrate the use of these models, focusing specifically on the mechanisms for arrhythmogenesis and defibrillation in the heart. These include: (1) uncovering the role of ventricular structure in defibrillation; (2) examining the contribution of Purkinje fibres to the failure of the shock; and (3) using magnetic resonance imaging reconstructed heart models to investigate the re-entrant circuits formed in the presence of an infarct scar. |
6,836 | Acute atrial tachyarrhythmia induces angiotensin II type 1 receptor-mediated oxidative stress and microvascular flow abnormalities in the ventricles. | Patients with paroxysmal atrial fibrillation (AF) often present with typical angina pectoris and mildly elevated levels of cardiac troponin (non ST-segment elevation myocardial infarction) during an arrhythmic event. However, in a large proportion of these patients, significant coronary artery disease is excluded by coronary angiography. Here we explored the potential underlying mechanism of these events.</AbstractText>A total of 14 pigs were studied using a closed chest, rapid atrial pacing (RAP) model. In five pigs RAP was performed for 7 h (600 b.p.m.; n = 5), in five animals RAP was performed in the presence of angiotensin-II type-1-receptor (AT(1)-receptor) inhibitor irbesartan (RAP+Irb), and four pigs were instrumented without intervention (Sham). One-factor analysis of variance was performed to assess differences between and within the three groups. Simultaneous measurements of fractional flow reserve (FFR) and coronary flow reserve (CFR) before, during, and after RAP demonstrated unchanged FFR (P = 0.327), but decreased CFR during RAP (RAP: 67.7 +/- 7.2%, sham: 97.2 +/- 2.8%, RAP+Irb: 93.2 +/- 3.3; P = 0.0013) indicating abnormal left ventricular (LV) microcirculation. Alterations in microcirculatory blood flow were accompanied by elevated ventricular expression of NADPH oxidase subunit Nox2 (P = 0.039), lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1, P = 0.004), and F(2)-isoprostane levels (P = 0.008) suggesting RAP-related oxidative stress. Plasma concentrations of cardiac troponin-I (cTn-I) increased in RAP (RAP: 613.3 +/- 125.8 pmol/L vs. sham: 82.5 +/- 12.5 pmol/L; P = 0.013), whereas protein levels of eNOS and LV function remained unchanged. RAP+Irb prevented the increase of Nox2, LOX-1, and F(2)-isoprostanes, and abolished the impairment of microvascular blood flow.</AbstractText>Rapid atrial pacing induces AT(1)-receptor-mediated oxidative stress in LV myocardium that is accompanied by impaired microvascular blood flow and cTn-I release. These findings provide a plausible mechanism for the frequently observed cTn-I elevation accompanied with typical angina pectoris symptoms in patients with paroxysmal AF and normal (non-stenotic) coronary arteries.</AbstractText> |
6,837 | Intramural left atrial haematoma mimicking cardiac tamponade after catheter ablation of atrial fibrillation. | Catheter ablation is an established treatment modality for patients with drug refractory atrial fibrillation (AF). This procedure carries a 6% major complication rate including cardiac tamponade due to cardiac perforation. We report on a patient with clinical signs of cardiac tamponade due to a diffuse intramural left atrial haematoma obstructing left ventricular filling after catheter ablation of AF. |
6,838 | Role of congenital long-QT syndrome in unexplained sudden infant death: proposal for an electrocardiographic screening in relatives. | Congenital long-QT syndrome (LQTS) is a sporadic or familial inherited arrhythmia. It can lead to sudden death by ventricular fibrillation which occurs at any age but particularly during infancy. Recent studies of postmortem molecular analysis in infants who died of unexplained sudden infant death syndrome (SIDS) showed abnormal mutations to LQTS in 10% to 12%. Current methods of etiologic investigation of sudden infant death syndrome do not allow the diagnosis of LQTS. A targeted anamnesis together with systematic electrocardiograms of first- and second-degree relatives could be an efficient LQTS diagnostic tool. Therefore, we propose to include them in screening procedures for SIDS etiologies.</AbstractText>LQTS accounts for a significant number of unexplained SIDS. We suggest adding a systematic familial electrocardiographic screening to the current etiologic investigations in order to track congenital LQTS in relatives.</AbstractText> |
6,839 | The conundrum of ventricular arrhythmia and cardiomyopathy: which abnormality came first? | Ventricular arrhythmia and cardiomyopathy often coexist. Many patients with abnormal ventricular function have either documented premature ventricular contractions (PVCs) or nonsustained ventricular tachycardia and have an increased risk of sudden death from ventricular fibrillation. Tachycardia is a treatable cause of cardiomyopathy. The culprit arrhythmia may be atrial tachycardia, atrial fibrillation, or another supraventricular arrhythmia. The syndrome of PVCs giving rise to ventricular dysfunction was recently described. Thus, a conundrum exists for clinicians in determining which abnormality (PVCs or cardiomyopathy) came first and gave rise to the other. Solving this dilemma is important because radiofrequency ablation for frequent PVCs can completely reverse the cardiomyopathy and normalize systolic ventricular function. In this article, we describe the present evidence for the syndrome of PVCs that can be ablated as a cause for cardiomyopathy. We include a case example and discussion to illustrate this concept and provide a stepwise approach to determining whether PVCs cause cardiomyopathy or vice versa. |
6,840 | The DAVID (Dual Chamber and VVI Implantable Defibrillator) II trial. | The purpose of this study was to determine whether atrial pacing is a safe alternative to minimal (backup-only) ventricular pacing in defibrillator recipients with impaired ventricular function.</AbstractText>The DAVID (Dual Chamber and VVI Implantable Defibrillator) trial demonstrated that dual chamber rate responsive pacing as compared with ventricular backup-only pacing worsens the combined end point of mortality and heart failure hospitalization. Although altered ventricular activation from right ventricular pacing was presumed to be the likely cause for these maladaptive effects, this supposition is unproven.</AbstractText>In all, 600 patients with impaired ventricular function from 29 North American sites, who required an implanted defibrillator for primary or secondary prevention, with no clinical indication for pacing, were randomly assigned to atrial pacing (at 70 beats/min) versus minimal ventricular pacing (at 40 beats/min) and followed up for a mean of 2.7 years.</AbstractText>There were no significant differences between pacing arms in patients' baseline characteristics, use of heart failure medications, and combined primary end point of time to death or heart failure hospitalization during follow-up, with an overall incidence of 11.1%, 16.9%, and 24.6% at 1, 2, and 3 years, respectively. Similarly, the incidence of atrial fibrillation, syncope, appropriate or inappropriate shocks, and quality of life measures did not significantly differ between treatment groups.</AbstractText>The effect of atrial pacing on event-free survival and quality of life was not substantially worse than, and was likely equivalent to, backup-only ventricular pacing. Atrial pacing may be considered a "safe alternative" when pacing is desired in defibrillator recipients, but affords no clear advantage or disadvantage over a ventricular pacing mode that minimizes pacing altogether. (Dual Chamber and VVI Implantable Defibrillator [DAVID] Trial II; NCT00187187).</AbstractText> |
6,841 | Blood pressure levels, left ventricular mass and function are correlated with left atrial volume in mild to moderate hypertensive patients. | Arterial hypertension is associated with an increased risk of atrial fibrillation (AF), and leads to a pronounced increase in morbidity and mortality. Left atrial volume (LAV) is an important prognostic marker in the older populations. The aim of our study was to identify the clinical and echocardiographic determinants of LAV in middle-aged (<70 years old) essential hypertensive patients.We evaluated cardiac structure and function in 458 patients, 394 treated and untreated mild to moderate essential hypertensives patients (mean+/-s.d. age 48.4+/-11.1 years) with no associated clinical condition and 64 normotensive control participants (age 45.7+/-12.8 years; P=0.12). A multivariate analysis was performed to calculate the relative weight of each of the variables considered able to predict LAV. The LAV index (LAVi) was significantly increased in the essential hypertensive group vs the control group and was significantly dependent on blood pressure levels (SBP and DBP, P<0.05 for both) and body mass index (BMI) (P<0.0001). Considering the left ventricular (LV) variables, the LV mass index (LVMI) (R(2)=0.19, P<0.001) and LAV were increased in essential hypertensive patients with left ventricular hypertrophy (LVH), and patients with enlarged LAV showed lower systolic and diastolic function and an increased LVMI. The LAVi is dependent on blood pressure levels and anthropometric variables (age and BMI). Further structural (LVMI) and functional (systolic and diastolic) variables are related to the LAVi; LVMI is the most important variable associated with LAV in mild to moderate essential hypertensive adult patients. These findings highlight the importance of left atrium evaluation in adult, relatively young, essential hypertensive patients. |
6,842 | Defibrillation in clinical practice. | To discuss recent data that may influence defibrillation in clinical practice and improve outcome after cardiac arrest from a shockable rhythm.</AbstractText>Reducing the preshock pause (interval between stopping chest compressions and shock delivery) improves shock success. The preshock pause can be reduced by continuing chest compressions during defibrillator charging and using performance-integrated debriefing to improve the efficiency of the resuscitation team. The findings of a study documenting leakage current during elective cardioversion imply that the risk to healthcare personnel of accidental electrocution during defibrillation has probably been overstated. One study has shown that when more than one shock is required, a strategy of escalating defibrillation energies may be more effective than using a fixed energy. Findings from three recent studies suggest that the precordial thump is ineffective for terminating ventricular fibrillation or ventricular tachycardia.</AbstractText>A defibrillation strategy that enables rhythm analysis to recognize ventricular fibrillation, defibrillator charging and optimally timed shock delivery with minimal or no interruptions to chest compressions should improve the chances of shock success. Performance debriefing of rescuers and recognizing that the risk to rescuers during defibrillation has been overstated should also help minimize interruptions to chest compressions for shock delivery.</AbstractText> |
6,843 | Importance of dual induction tests for coronary vasospasm and ventricular fibrillation in patients surviving out-of-hospital cardiac arrest. | The pathogenesis of out-of-hospital cardiac arrest (OHCA) without organic heart disease has not been fully investigated.</AbstractText>Induction tests were performed in 12 consecutive patients with OHCA for both coronary vasospasm with intracoronary acetylcholine and ventricular fibrillation (VF) with programmed stimulation at 1 month after the event. All patients were positive for 1 of the tests: coronary vasospasm alone in 3, VF alone in 2, and both in 7. All patients underwent implantable cardioverter defibrillator (ICD) implantation and appropriate ICD shock was documented in 1 patient.</AbstractText>OHCA has a heterogeneous pathogenesis and so dual induction tests are necessary.</AbstractText> |
6,844 | Autonomic elements within the ligament of Marshall and inferior left ganglionated plexus mediate functions of the atrial neural network. | We sought to systematically investigate the role of the ligament of Marshall (LOM) and inferior left ganglionated plexi (ILGP) in modulating electrophysiological functions.</AbstractText>The following structures were exposed in 36 dogs: (1) LOM, (2) superior left GP (SLGP) near the junction of left superior pulmonary vein (LSPV) and left atrium, (3) ILGP near the left inferior pulmonary vein-atrial junction, (4) anterior right GP (ARGP) near the sino-atrial node, and (5) inferior right GP (IRGP) at the junction of inferior vena cava and atria. High frequency stimulation (HFS; 0.6-8.0 V, 20 Hz, 0.1 msec in duration) was applied to the LOM, SLGP, ILGP, ARGP, IRGP, or vagosympathetic trunk. Ventricular rate (VR) during atrial fibrillation (AF) was compared before and after ablation of GP in different sequences.</AbstractText>ARGP + ILGP ablation but not ARGP ablation alone eliminated the VR slowing response induced by LOM stimulation, suggesting that all the autonomic innervation from the LOM to AV node passes the ILGP. LOM ablation attenuated the VR slowing response caused by SLGP or left vagosympathetic stimulation, suggesting that LOM modulates the autonomic innervation between the AV node and the left vagosympathetic trunk or SLGP. ARGP attenuated while ARGP + ILGP ablation eliminated the VR slowing response induced by left vagosympathetic stimulation, suggesting that both ARGP and ILGP modulate the AV nodal innervation of the extrinsic and intrinsic cardiac autonomic nervous system (ANS).</AbstractText>The LOM and ILGP function as the "integration centers" that modulate the autonomic interactions between extrinsic and intrinsic cardiac ANS on AV nodal function.</AbstractText> |
6,845 | Non-invasive prediction of ST elevation myocardial infarction complications by left ventricular Tei index. | To investigate association between the Tei index and cardiac complications of ST elevation of Myocardial Infarction.</AbstractText>A total of a 202 adult consecutive patients with first ST elevation MI (STEMI) were studied. Tei index was obtained as: (a _ b)/b, where "a" is the interval between the cessation and onset of mitral flow and "b" is the ejection time of aortic flow measured with the help of pulsed Doppler echocardiography. Subsequent complications, included Death, Congestive Heart Failure (CHF), Cardiogenic shock, Atrial Flutter/ Atrial Fibrillation, Sustained ventricular tachycardia, Advanced Atrio- Ventricular Clock (AV Block), Myocardial Infarction (MI), Readmission (due to any cardiac cause) and Revascuralarization during the 30 days after the onset of Acute STEMI were prospectively evaluated and compared with the initial Tei index at admission.</AbstractText>Complications were noted in 60% of the patients with acute STEMI. The Tei index was significantly increased for patients with complications compared with those without them (0.66 +/- 0.13 vs. 0.30 +/- 0.10, P < .0001). When Tei index > 0.40 was used for the criteria, the sensitivity, specificity, and overall accuracy to predict subsequent complications were 86%, 82%, and 83%, respectively.</AbstractText>Tei index allows approximate but quick and practical noninvasive prediction of complications in patients with STEMI.</AbstractText> |
6,846 | Implantable cardioverter-defibrillator implantation in a patient with atrial standstill. | We report a 55-year-old female patient who presented with no P waves but with a wide QRS complex escape rhythm at 44 beats/min and prolonged QTc of 0.55 seconds on ECG. The patient had recurrence of ventricular fibrillations and loss of consciousness, and underwent defibrillation and cardiopulmonary resuscitation (CPR) several times because of cardiac arrest. The transthoracic echocardiography showed dilated cardiomyopathy and enlargement of both atria. The Doppler echocardiography documented the absence of A wave in the tricuspid and mitral valve flow. An electrophysiologic study demonstrated electrical inactivity in the right and left atria. Atrial pacing with maximum output did not capture the atria. These findings together with her electrocardiographic finding indicated atrial standstill. Sudden cardiac death was her first clinical manifestation of ventricular arrhythmia. The patient remained asymptomatic after receiving a single chamber implantable cardioverter-defibrillator (ICD) with VVI pacemaker function. |
6,847 | Wireless cardiac event alert monitoring is feasible and effective in the emergency department and adjacent waiting areas. | The need for vigilance for unexpected clinical deterioration in the emergency department (ED) waiting area and in unmonitored treatment areas of the ED continues to increase. We sought to determine in an observational study the feasibility and relative false-alarm burden of, and satisfaction with, a novel wireless automated clinician alert device for cardiac rate and rhythm derangements in a teaching hospital ED. Patients presenting with a variety of complaints who after ED triage were not placed on conventional telemetric monitoring (by standard triage policy) were considered for inclusion. Those enrolled in the study were then monitored in the waiting room and in the ED proper via a wireless, one-lead ECG device that, through relay hubs installed in the ED ceiling, alerted clinicians via desktop computers at regular ED work stations to the presence of asystole, ventricular fibrillation, and bradycardia and tachycardia in those patients. The device is not a conventional telemetry monitor, in that it does not provide streaming visual monitoring capability; instead, it provides alarms and one-lead ECG data when triggered by specific rate and rhythm deviations.A total of 298 ED patients (30.2% patients triaged after a run-in period) were monitored, for a mean duration of 3.53 hours. Productive clinical alarms (those that prompted a change in patient therapy, location, or intensity of monitoring) occurred in 20 patients (6.7%); the most common response to an alert was earlier transition from the waiting room into a clinical space in the ED. There were 10 false-positive asystole or ventricular fibrillation alarms in 4 patients (1.3%), all of which were readily attributable to nonclinical origins, such as poor lead adherence. There was excellent satisfaction with the device from both patients and clinical personnel. Wireless cardiac event monitoring is feasible in the ED, and improves the throughput of ED patients with worsening vital signs, and may improve overall patient safety, without an onerous burden of nonproductive alarms. |
6,848 | [Cardiac autotransplantation in a patient with congestive heart failure]. | Congestive heart failure with intact or moderately lowered left ventricular pump function is caused in some patients by mitral regurgitation. Consequences are dilation of the left atrium, pulmonary hypertension, tricuspid regurgitation, thromboembolic complications, rhythm disturbances, elevated risk of sudden death. Efficacy of drug treatment, electroimpulse therapy is little and surgery is the method of choice. One of alternatives is cardiac autotransplantation. A successful experience of application of this technique is presented. Cardiac autotransplantation was carried out in a female patient with moderately lowered left ventricular contractile function, extreme degree of mitral and tricuspid regurgitation, atriomegaly, atrial fibrillation and pronounced signs of congestive heart failure. |
6,849 | Resolution of established cardiac hypertrophy and fibrosis and prevention of systolic dysfunction in a transgenic rabbit model of human cardiomyopathy through thiol-sensitive mechanisms. | Cardiac hypertrophy, the clinical hallmark of hypertrophic cardiomyopathy (HCM), is a major determinant of morbidity and mortality not only in HCM but also in a number of cardiovascular diseases. There is no effective therapy for HCM and generally for cardiac hypertrophy. Myocardial oxidative stress and thiol-sensitive signaling molecules are implicated in pathogenesis of hypertrophy and fibrosis. We posit that treatment with N-acetylcysteine, a precursor of glutathione, the largest intracellular thiol pool against oxidative stress, could reverse cardiac hypertrophy and fibrosis in HCM.</AbstractText>We treated 2-year-old beta-myosin heavy-chain Q403 transgenic rabbits with established cardiac hypertrophy and preserved systolic function with N-acetylcysteine or a placebo for 12 months (n=10 per group). Transgenic rabbits in the placebo group had cardiac hypertrophy, fibrosis, systolic dysfunction, increased oxidized to total glutathione ratio, higher levels of activated thiol-sensitive active protein kinase G, dephosphorylated nuclear factor of activated T cells (NFATc1) and phospho-p38, and reduced levels of glutathiolated cardiac alpha-actin. Treatment with N-acetylcysteine restored oxidized to total glutathione ratio, normalized levels of glutathiolated cardiac alpha-actin, reversed cardiac and myocyte hypertrophy and interstitial fibrosis, reduced the propensity for ventricular arrhythmias, prevented cardiac dysfunction, restored myocardial levels of active protein kinase G, and dephosphorylated NFATc1 and phospho-p38.</AbstractText>Treatment with N-acetylcysteine, a safe prodrug against oxidation, reversed established cardiac phenotype in a transgenic rabbit model of human HCM. Because there is no effective pharmacological therapy for HCM and given that hypertrophy, fibrosis, and cardiac dysfunction are common and major predictors of clinical outcomes, the findings could have implications in various cardiovascular disorders.</AbstractText> |
6,850 | [Effect of hypotensive therapy on metalloproteinase activity of the blood in patients with arterial hypertension]. | Aim of the study--investigation of dynamics of levels of serum markers of myocardial fibrosis matrix metalloproteinase-1 (MMP-1), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1)--at the background of 3 months hypotensive therapy in 39 patients with arterial hypertension and paroxysmal form of atrial fibrillation. Twenty patients received sotalol, 19--retard form of verapamil. After 3 months of hypotensive therapy in all patients and separately in groups of patients receiving sotalol and verapamil no significant changes of MMP-1 and TIMP-1 occurred. However in patients with most pronounced hypotensive effect according to 24-hour blood pressure monitoring significant elevation of MMP-1 and lowering of TIMP-1 levels took place. This was associated with improvement of ventricular diastolic function. In most patients longer period of therapy (more than 3 months) is required for achievement of regression of damage to the heart. |
6,851 | [Wolf-Parkinson-White syndrome: stratification of syncope risk factors]. | To evaluate risk factors of syncopes in patients with Wolf-Parkinson-White syndrome (WPWS) using transesophageal pacing (TEP).</AbstractText>82 WPWS patients were divided into two groups: the study group (n = 46) with syncopes and presyncopes, the control group (n = 36) without syncopes. The groups were matched by sex and age. TEP protocol included two stages: before radiofrequency ablation (RFA) and on day 2 after RFA (control test).</AbstractText>Highly significant differences between the groups were detected only in induction of ortodromic tachycardia. In patients of the study group the cycle duration (CD) was 317 +/- 38.9 ms, in the control group - 365.25 +/- 96.3 ms (R = 0.003), heart rate--197.7 +/- 15.03 vs 167.3 +/- 31.65 per 1 min (R = 0.003), heart rate--197.7 +/- 15.03 vs 167.3 +/- 31.65 per 1 min (R = 0.0001), ventricular interval--122.5 +/- 17.5 and 153.1 +/- 44.4 ms (R = 0.0001). A correlation was found between syncope risk and baseline heart rate, CD, Venkebach point, antegrade effective refractory period of additional atrioventricular connection, ventriculoatrial interval during tachycardia, WPWS manifestation, atrial fibrillation, arrhythmia history.</AbstractText>The detected electrophysiological changes allow early detection of patients at high syncope risk among WPWS patients and reduction of sudden cardiac death risk in these patients.</AbstractText> |
6,852 | [Pacemaker implantation in a patient with cor triatriatum sinister - preoperative evaluation]. | A case of 72 year old-male with cor triatriatum sinister, permanent atrial fibrillation and symptomatic bradycardia is presented. Patient was scheduled for pacemaker implantation. A preoperative evaluation with transesophageal echocardiography revealed a nonrestrictive membrane in left atrium, normal right superior vena cava and absence of persistent left superior vena cava and other cardiac anomalies. A right ventricular pacemaker lead was implanted through left subclavian approach. Preoperative evaluation shortened a radiation exposure and procedure time. |
6,853 | Ventricular tachycardia and sudden cardiac death. | Ventricular tachycardia (VT), which most commonly occurs in patients with structural heart disease, can be associated with an increased risk of sudden death. The most common cause of ventricular fibrillation is acute coronary ischemia, whereas a myocardial scar from prior infarct is the most common cause of sustained monomorphic VT in patients with structural heart disease. More benign forms of idiopathic VT can also occur in the absence of structural heart disease. Treatment of VT involves both emergent management and prevention of recurrence with medical and device therapy. Appropriately selected patients who have experienced VT or those who are at risk of VT may be candidates for an implantable cardioverter-defibrillator. The left ventricular ejection fraction is most frequently used to stratify patients with either ischemic or nonischemic cardiomyopathy who are at risk of sudden death and may be candidates for a prophylactic defibrillator. Catheter ablation may also be an option for appropriately selected patients with many forms of VT. This article discusses the etiologies and management of VT and its association with sudden death. |
6,854 | Mechanisms of VF maintenance: wandering wavelets, mother rotors, or foci. | Ventricular fibrillation (VF), despite its declining incidence as a cause of sudden cardiac death, is still a major health problem. The underlying mechanisms for the maintenance of VF are still disputed. Studies suggest that VF is unlikely one static mechanism but rather a dynamic process of electrical derangement that changes with duration. The 2 principal proposed mechanisms of VF are multiple wavelets and mother rotors. Most studies of these proposed mechanisms for VF maintenance have been during the first minute of VF. However, the time to external defibrillation in the community and pre-hospital settings, where the majority of sudden cardiac death occurs, ranges from 4 to 10 min and the time to defibrillation seems crucial because the odds of survival worsen with delay. Recent studies during the first 10 min of VF suggest that Purkinje fibers are important in maintaining VF after the first 1 to 2 min, either as a part of a reentrant circuit or as a source of focal activations. |
6,855 | Increased cycle length during long-duration ventricular fibrillation is caused by decreased upstroke velocity as well as prolonged refractoriness. | Cycle length (CL) increases as ventricular fibrillation (VF) progresses.</AbstractText>The purpose of this study was to test the hypotheses that increased CL is due to increased diastolic interval (DI), not increased action potential duration (APD), and that the DI increase is not solely due to increased postrepolarization refractoriness.</AbstractText>In 10 swine, VF was recorded for 20 minutes using a floating microelectrode through a hole in a 504-electrode epicardial plaque. Mean APD, DI, action potential amplitude (APA), maximum change in voltage during the AP upstroke (V(max)), and CL were calculated from the floating microelectrode recordings each minute of VF. The refractory period was estimated from the minimum DI (DI(min)). In two animals, rapid pacing was performed to gauge refractoriness.</AbstractText>As VF progressed, CL, DI, and DI(min) increased (P <.05), whereas APD, V(max), and APA decreased (P <.05). At 20 minutes, DI(min) was not different from mean DI at VF onset. Pacing captured, but 53% of paced wavefronts blocked within the plaque.</AbstractText>Increasing CL in VF is due to increased DI and not APD, which shortens. The increase in DI(min) over time is much less than the increase in mean DI, indicating that the myocardium is excitable during much of the DI. This finding, along with the ability to pace at a CL shorter than the native VF CL and the poor paced wavefront propagation, suggests that the increase in DI is due not only to increased postrepolarization refractoriness but also to poor wavefront propagation because of decreased APA and V(max) secondary to global ischemia caused by VF.</AbstractText> |
6,856 | Clinical importance of new-onset atrial fibrillation after cardiac resynchronization therapy. | Data on the occurrence and implications of new-onset atrial fibrillation (AF) following cardiac resynchronization therapy (CRT) are scarce. We studied the incidence of new onset AF in CRT-defibrillator (CRT-D) recipients. The influence of new-onset AF on echocardiographic response to CRT and the rate of adverse events also were evaluated.</AbstractText>The purpose of this study was to assess the incidence and implications of new-onset AF following CRT.</AbstractText>The study population consisted of 223 consecutive patients with no history of AF. New-onset AF was defined as atrial high-rate episodes >180 bpm for more than 10 minutes/day as detected by the device. Echocardiography was performed at baseline and after 6 months of biventricular pacing. Long-term events included implantable cardioverter-defibrillator therapy for ventricular arrhythmias, hospitalization for heart failure, and all-cause mortality.</AbstractText>Fifty-five (25%) patients developed new-onset AF during mean follow-up of 32 +/- 16 months. When compared to the patients who maintained sinus rhythm during follow-up, patients who developed AF showed less left ventricular (LV) reverse remodeling (DeltaLV end-systolic volume 37 +/- 53 vs >19 +/- 37 mL, P <.05) and less improvement in LV function (DeltaLV ejection fraction 6.7% +/- 8.9% vs 3.5% +/- 10.3%, P <.05). Importantly, patients who developed AF experienced more appropriate ICD shocks for ventricular arrhythmias, more inappropriate shocks, and more hospitalizations for heart failure.</AbstractText>Recipients of CRT-D who develop new-onset AF show less echocardiographic response to CRT and more cardiac adverse events during long-term follow-up.</AbstractText> |
6,857 | Computer simulation of atypical Brugada syndrome. | Recently, the so-called atypical Brugada syndrome (BS) has been reported in few cases in literature. The typical BS is characterized by ST-segment elevation in the right precordial leads, whereas atypical forms of the disease are distinguished by electrocardiogram abnormalities of the J wave, and ST-segment elevation appeared in the inferior and lateral leads. In this work, we report a simulation of atypical BS based on a 3-dimensional whole-heart model. By setting the action potentials of Brugada model cells in different epicardial regions, we calculated 12-lead electrocardiogram and body surface potentials that are in good agreement with clinical data. Applying additional electrical stimuli, we obtained the induction of ventricular fibrillation in both typical and atypical BS forms. The calculated results confirm possibility of similar electrophysiological basis in both cases and suggest that BS can also be observed in inferior and lateral precordial leads. |
6,858 | Intra-arrest hypothermia: both cold liquid ventilation with perfluorocarbons and cold intravenous saline rapidly achieve hypothermia, but only cold liquid ventilation improves resumption of spontaneous circulation. | Rapid intra-arrest induction of hypothermia using total liquid ventilation (TLV) with cold perfluorocarbons improves resuscitation outcome from ventricular fibrillation (VF). Cold saline intravenous infusion during cardiopulmonary resuscitation (CPR) is a simpler method of inducing hypothermia. We compared these 2 methods of rapid hypothermia induction for cardiac resuscitation.</AbstractText>Three groups of swine were studied: cold preoxygenated TLV (TLV, n=8), cold intravenous saline infusion (S, n=8), and control (C, n=8). VF was electrically induced. Beginning at 8 min of VF, TLV and S animals received 3 min of cold TLV or rapid cold saline infusion. After 11 min of VF, all groups received standard air ventilation and closed chest massage. Defibrillation was attempted after 3 min of CPR (14 min of VF). The end point was resumption of spontaneous circulation (ROSC).</AbstractText>Pulmonary arterial (PA) temperature decreased after 1 min of CPR from 37.2 degrees C to 32.2 degrees C in S and from 37.1 degrees C to 34.8 degrees C in TLV (S or TLV vs. C p<0.0001). Coronary perfusion pressure (CPP) was higher in TLV than S animals during the initial 3 min of CPR. Arterial pO(2) was higher in the preoxygenated TLV animals. ROSC was achieved in 7 of 8 TLV, 2 of 8 S, and 1 of 8C (TLV vs. C, p=0.03).</AbstractText>Moderate hypothermia was achieved rapidly during VF and CPR using both cold saline infusion and cold TLV, but ROSC was higher than control only in cold TLV animals, probably due to better CPP and pO(2). The method by which hypothermia is achieved influences ROSC.</AbstractText> |
6,859 | Quinidine revisited. | One of the earliest antiarrhythmic drugs developed, quinidine had a significant role in the treatment of many arrhythmias. After concerns for increased risk of ventricular arrhythmia and death with quinidine emerged, the use of quinidine fell dramatically in favor of newer antiarrhythmic medications. However, recent trials have generated renewed interest in the use of quinidine. In particular, quinidine appears to be safe and efficacious in combination with verapamil for the treatment of atrial fibrillation. Quinidine has also been used successfully to treat idiopathic ventricular fibrillation, Brugada syndrome, and Short QT syndrome. Although it is one of the oldest drugs in our armamentarium, quinidine continues to have a role in modern cardiology. |
6,860 | [Prevalence of left ventricular hypertrophy, atrial fibrillation and cardiovascular disease in hypertensive patients of Andalusia, Spain. PREHVIA study]. | The objective of the PREHVIA study was to assess the prevalence of electrocardiographic left ventricular hypertrophy (ECG-LVH) and of atrial fibrillation (AF) among Andalusian hypertensive patients, and the relationship of this complications with cardiovascular disease (CVD).</AbstractText>Cross-sectional study with selection of study centres following the distribution of the Andalusian population by provinces and habitat, and randomization of patients included in the sample. Personal history was recorded, and ECG-LVH was assessed using the Cornell (voltage and product) and Sokolow-Lyon criteria, applied by the participant physicians and by an expert cardiologist. The association with ECG-HVH or CVD was studied by logistic regression models.</AbstractText>In 570 patients (mean age 65 years, 54.5% women, 50.6% with obesity, 28,2% with diabetes), the prevalence of ECG-LVH was 13.7% (95% confidence interval [CI], 10.8-16.6%). Cornell criterion was fulfilled by 12.6% and Sokolow-Lyon by 1.6%. The prevalence of AF was 5.1% (95% CI, 3.9-7.5%) and 22.1% (95% CI, 18.4-25.4%) had established CVD. In the multivariate analysis, ECG-LVH was associated with female gender (odds ratio=5.10; 95% CI, 2.44-10.64) and with the presence of CVD (odds ratio=2.18; 95% CI, 1.09-4.12). The antecedent of CVD was independently associated with an advanced age, male gender, AF and, less strongly, with low glomerular filtration rate and diabetes mellitus.</AbstractText>In Andalusian hypertensives, the prevalence of ECG-LVH was significantly lower than that found in other studies, greater in women and at the expense of the Cornell criterion, the prevalence of AF was 5.1% and it was 22.1% for CVD with independent associations between ECG-LVH and between CVD and AF.</AbstractText> |
6,861 | Normal impulse propagation in the atrioventricular conduction system of Cx30.2/Cx40 double deficient mice. | Connexin (Cx) 30.2, Cx40 and Cx45 containing gap junctional channels contribute to electrical impulse propagation through the mouse atrioventricular node (AV-node). The cross talk in between these Cxs may be of great importance for AV-nodal conduction. We generated Cx30.2/Cx40 double deficient mice (Cx30.2(LacZ/LacZ)Cx40(-/-)) and analyzed the relative impact of Cx30.2 and Cx40 on cardiac conductive properties in vivo by use of electrophysiological examination. Cx30.2(LacZ/LacZ)Cx40(-/-) mice exhibited neither obvious cardiac malformations nor impaired contractile function. In surface-ECG analyses, Cx30.2(LacZ/LacZ)Cx40(-/-) and Cx40 deficient animals (Cx40(-/-)) showed significantly longer P-wave durations, PQ-intervals and prolonged QRS-complexes relative to wildtype littermates (WT). Cx30.2-deficient mice (Cx30.2(LacZ/LacZ)) developed shorter PQ-intervals as compared to WT, Cx40(-/-) or Cx30.2/Cx40 double deficient mice. Intracardiac evaluation of the atria-His (AH) and His-ventricle (HV) intervals representing supra and infra-Hisian conduction yielded significant acceleration of supra-Hisian conductivity in Cx30.2(LacZ/LacZ) (AH: 28.2+/-4.3 ms) and prolongation of infra-Hisian conduction in Cx40(-/-) mice (HV: 13.7+/-2.6 ms). These parameters were unchanged in the Cx30.2(LacZ/LacZ)Cx40(-/-) mice (AH: 37.3+/-5.5 ms, HV: 11.7+/-2.6 ms), which exhibited AV-nodal and ventricular conduction times similar to WT animals (AH: 35.9+/-4.4 ms, HV: 10.5+/-1.9 ms). We conclude that the remaining Cx45 gap junctional channels are sufficient to maintain electrical coupling and cardiac impulse propagation in the AV-node and proximal ventricular conduction system in mice. We suggest that Cx30.2 and Cx40 act as counterparts in the AV-node and His-bundle, decreasing or increasing, respectively, electrical coupling and conduction velocity in these areas. |
6,862 | Mitral valve disease in pregnancy: outcomes and management. | Young women may have asymptomatic mitral valve disease which becomes unmasked during the haemodynamic stress of pregnancy. Rheumatic mitral stenosis is the most common cardiac disease found in women during pregnancy. The typical increased volume and heart rate of pregnancy are not well tolerated in patients with more than mild stenosis. Maternal complications of atrial fibrillation and congestive heart failure can occur, and are increased in patients with poor functional class and severe pulmonary artery hypertension. Patients can be diagnosed by echocardiography and symptoms treated with beta-1 antagonists and cautious diuresis. Patients with heart failure unresponsive to treatment can undergo percutaneous balloon mitral valvuloplasty. Labour and delivery goals include reducing tachycardia by adequate pain control and minimized volume shifts. Mitral valve regurgitation, even when severe, is usually very well tolerated in pregnancy as the increase in volume is offset by a decrease in vascular resistance. On the other hand, patients with left ventricular dysfunction, moderate pulmonary hypertension or NYHA functional class III-IV are at increased risk for heart failure and arrhythmias. They may need cautious diuresis and limitations on physical activity during pregnancy, as well as invasive haemodynamic monitoring for labour and delivery. Vaginal delivery is preferred and caesarean section reserved for obstetric indications. |
6,863 | Therapeutical hypothermia after cardiopulmonary resuscitation: evidences and practical issues. | Cardiac arrest survivors frequently suffer from ischemic brain injury associated with poor neurological outcome and death. Therapeutic hypothermia improves outcomes in comatose survivors after resuscitation from out-of-hospital cardiac arrest. Considering its formal recommendation as a therapy, post-return of spontaneous circulation after cardiac arrest, the objective of this study was to review the clinical aspects of therapeutic hypothermia. Non-systematic review of articles using the keywords "cardiac arrest, cardiopulmonary resuscitation, cooling, hypothermia, post resuscitation syndrome" in the Med-Line database was performed. References of these articles were also reviewed. Unconscious adult patients with spontaneous circulation after out-of-hospital ventricular fibrillation or pulseless ventricular tachycardia should be cooled. Moreover, for any other rhythm or in the intra-hospital scenario, such cooling may also be beneficial. There are different ways of promoting hypothermia. The cooling system should be adjusted as soon as possible to the target temperature. Mild therapeutic hypothermia should be administered under close control, using neuromuscular blocking drugs to avoid shivering. The rewarming process should be slow, and reach 36º C, usually in no less then 8 hours. When temperature increases to more than 35º C, sedation, analgesia, and paralysis could be discontinued. The expected complications of hypothermia may be pneumonia, sepsis, cardiac arrhythmias, and coagulopathy. In spite of potential complications which require rigorous control, only six patients need to be treated to save one life. |
6,864 | Autoimmune mechanisms underlying dilated cardiomyopathy. | Autoimmune abnormalities, as well as viral infection and genetic abnormalities, appear to be major predisposing factors for dilated cardiomyopathy (DCM). Abnormalities of cell-mediated immunity are mainly involved in the onset of cardiomyopathy secondary to myocarditis. However, various antimyocardial antibodies are detected in the serum of patients with DCM. The appearance of these antibodies was considered to be an epiphenomenon associated with myocyte injury resulting from myocarditis, but recent findings have suggested that at least some of them are directly related to the pathophysiology of DCM. In particular, an autoantibody targeting the beta1-adrenergic receptor that exhibits an agonist-like effect is related to the persistent myocardial damage resulting in DCM and provides substrates for fatal ventricular arrhythmias. In addition, an antibody for the muscarinic M2 receptor is related to atrial fibrillation, an antibody targeting Na-K-ATPase is closely related to sudden cardiac death as a result of fatal ventricular arrhythmias, and an autoantibody for troponin I increases the L-type calcium current and is related to the myocardial damage. Based on these findings, immunoadsorption therapy was developed to remove such autoantibodies in patients with refractory heart failure as a result of DCM. |
6,865 | The emerging role of antiarrhythmic compounds with atrial selectivity in the management of atrial fibrillation. | Atrial fibrillation represents a significant source of cardiovascular morbidity and mortality in the United States. Despite a relatively high clinical failure rate, pharmacologic conversion to and maintenance of normal sinus rhythm with antagonists of the HERG potassium channel responsible for carrying the delayed rectifier current I(Kr) represent a mainstay of therapy. Suppression of I(Kr) leads to restoration of normal sinus rhythm but is also associated with ventricular proarrhythmia. Given the unique electrophysiologic targets expressed in human atrium, compounds that exhibit selectivity for these targets have the potential to restore sinus rhythm with a reduced risk of ventricular proarrhythmia. Targets with expression limited to human cardiac atria and compounds that interact with these targets are reviewed. |
6,866 | Bioequivalence of 2 intravenous amiodarone formulations in healthy participants. | Intravenous amiodarone is an effective agent for the treatment of recurrent ventricular fibrillation and hemodynamically unstable ventricular tachycardia. PM101 is a new formulation of intravenous amiodarone that uses a cyclodextrin to maintain amiodarone in the aqueous phase. Eighty-eight participants were enrolled in this randomized, double-blind, crossover, bioequivalence clinical study and were treated with single doses (150 mg) of PM101 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 amiodarone plasma concentration-time curve observed with both formulations was virtually identical, as was the 72-hour area under the curve (AUC0-72). Similar equivalence was seen for desethylamiodarone, the active metabolite of amiodarone. The geometric ratios of the AUC0-72 for amiodarone and desethylamiodarone were 1.03 (95% confidence interval [CI], 1.00-1.06) and 1.01 (0.99-1.03), respectively. Similar geometric ratios and CIs were found for maximum plasma concentration (Cmax) and for AUC extrapolated to infinity (AUC0-infinity). Because the 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 PM101 were identified. |
6,867 | Diagnostic accuracy and image quality of cardiac dual-source computed tomography in patients with arrhythmia. | Cardiac multi-detector computed tomography (MDCT) permits accurate visualization of high-grade coronary artery stenosis. However, in patients with heart rate irregularities, MDCT was found to have limitations. Thus, the aim of the present study was to evaluate the diagnostic accuracy of a new dual-source computed tomography (DSCT) scanner generation with 83 ms temporal resolution in patients without stable sinus rhythm.</AbstractText>44 patients (31 men, mean age 67.5+/-9.2 years) without stable sinus rhythm and scheduled for invasive coronary angiography (ICA) because of suspected (n=17) or known coronary artery disease (CAD, n=27) were included in this study. All patients were examined with DSCT (Somatom Definition, Siemens). Besides assessment of total calcium score, all coronary segments were analyzed with regard to the presence of significant coronary artery lesions (>50%). The findings were compared to ICA in a blinded fashion.</AbstractText>During CT examination, heart rhythm was as follows: 25 patients (57%) atrial fibrillation, 7 patients (16%) ventricular extrasystoles (two of them with atrial fibrillation), 4 patients (9%) supraventricular extrasystoles, 10 patients (23%) sinus arrhythmia (heart rate variability>10 bpm). Mean heart rate was 69+/-14 bpm, median 65 bpm. Mean Agatston score equivalent (ASE) was 762, ranging from 0 to 4949.7 ASE. Prevalence of CAD was 68% (30/44). 155 segments (27%) showed "step-ladder" artifacts and 28 segments (5%) could not be visualized by DSCT. Only 70 segments (12%) were completely imaged without any artifacts. Based on a coronary segment model, sensitivity was 73%, specificity 91%, positive predictive value 63%, and negative predictive value 94% for the detection of significant lesions (>or=50% diameter stenosis). Overall accuracy was 88%.</AbstractText>In patients with heart rate irregularities, including patients with atrial fibrillation and a high prevalence of coronary artery disease, the diagnostic yield of dual-source computed tomography is still hampered due to a high number of segments with "step-ladder" artifacts.</AbstractText>Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.</CopyrightInformation> |
6,868 | Anger-induced T-wave alternans predicts future ventricular arrhythmias in patients with implantable cardioverter-defibrillators. | This study sought to determine whether T-wave alternans (TWA) induced by anger in a laboratory setting predicts future ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs).</AbstractText>Anger can precipitate spontaneous ventricular tachycardia/ventricular fibrillation and induce TWA. Whether anger-induced TWA predicts future arrhythmias is unknown.</AbstractText>Sixty-two patients with ICDs underwent ambulatory electrocardiography during a mental stress protocol, 3 months after the ICD was implanted. T-wave alternans was analyzed using time-domain methods. After a > or =1 year follow-up, ICD stored data was reviewed to determine incidence of ICD-terminated ventricular tachycardia/ventricular fibrillation.</AbstractText>Patients with ICD-terminated arrhythmias during follow-up (n = 10) had higher TWA induced by anger, 13.2 microV (interquartile range [IQR] 9.3 to 16 microV), compared with those patients without future ventricular arrhythmias, 9.3 microV (IQR 7.5 to 11.5 microV, p < 0.01). Patients in the highest quartile of anger-induced TWA (>11.9 microV, n = 15) were more likely to experience arrhythmias by 1 year than those in the lower quartiles (33% vs. 4%) and during extended follow-up (40% vs. 9%, p < 0.01 for both). In multivariable regression controlling for ejection fraction, prior clinical arrhythmia, and wide QRS, anger-induced TWA remained a significant predictor of arrhythmia, with likelihood in the top quartile 10.8 times that of other patients (95% confidence interval: 1.6 to 113, p < 0.05).</AbstractText>Anger-induced TWA predicts future ventricular arrhythmias in patients with ICDs, suggesting that emotion-induced repolarization instability may be 1 mechanism linking stress and sudden death. Whether there is a clinical role for anger-induced TWA testing requires further study.</AbstractText> |
6,869 | [CRT in atrial fibrillation--methodical and apparatus options in decision-making]. | Heart failure and atrial fibrillation often coexist, especially with increasing degree of heart failure severity. Under this constellation, the advantage of cardiac resynchronization therapy (CRT) is still under discussion and displayed as an unresolved problem in the guidelines for cardiac stimulation and resynchronization. If ventricular desynchronization can be documented and response to CRT can be expected, the challenge is to interoperatively seek the best left ventricular electrode position and to postoperatively optimize the device in order to achieve the best therapy performance. This situation encourages the development of individualized methods and to utilize innovative apparatus features in order to consolidate individual decisions and to optimize CRT in heart failure with atrial fibrillation. |
6,870 | [Sandwiched between the single- and triple-chamber ICD: do we still need the dual-chamber ICD?]. | Since it has been shown that adverse events are more frequent with dual-compared to single-chamber ICDs in patients with heart failure, and since the importance of prevention of unnecessary right ventricular pacing and the success of biventricular pacing have been demonstrated in numerous studies, the need for dual-chamber ICD systems has to be reassessed. The development of these systems was accompanied by expectations of improved hemodynamics in patients with bradycardia, a reduced incidence of atrial fibrillation, inappropriate therapies, and bradycardia-associated ventricular tachyarrhythmias. Single-chamber ICDs should be used restrictively and with great caution in patients with (sinus-) bradycardia and heart failure, since a relevant proportion of these patients is at risk of hemodynamic deterioration. Even if the proportion of patients with proven pacemaker syndrome is so small that it does not reach the level of statistical significance in large studies, a small percentage of patients with hemodynamic deterioration due to VVI pacing is still clinically (and economically) intolerable. Since the development of bradycardia or symptomatic chronotropic incompetence (e.g., due to amiodarone) is difficult to predict, it seems reasonable to use the indication for dualchamber systems liberally. However, the systematic prevention of unnecessary right ventricular pacing is crucial if dual-chamber ICDs are used. If advanced tachycardia discrimination algorithms and careful, individual programming are used, dual-chamber ICDs are superior in the prevention of inappropriate therapies. Additionally, dualchannel electrograms allow a more reliable interpretation of stored tachycardia episodes. In summary, dual-chamber systems represent a valuable improvement of ICD therapy but require thorough programming to convey their advantage. |
6,871 | Scandinavian clinical practice guidelines for therapeutic hypothermia and post-resuscitation care after cardiac arrest. | Sudden cardiac arrest survivors suffer from ischaemic brain injury that may lead to poor neurological outcome and death. The reperfusion injury that occurs is associated with damaging biochemical reactions, which are suppressed by mild therapeutic hypothermia (MTH). In several studies MTH has been proven to be safe, with few complications and improved survival, and is recommended by the International Liaison of Committee on Resuscitation. The aim of this paper is to recommend clinical practice guidelines for MTH treatment after cardiac arrest from the Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI).</AbstractText>Relevant studies were identified after two consensus meetings of the SSAI Task Force on Therapeutic Hypothermia (SSAITFTH) and via literature search of the Cochrane Central Register of Controlled Trials and Medline. Evidence was assessed and consensus opinion was used when high-grade evidence (Grade of Recommendation, GOR) was unavailable. A management strategy was developed as a consensus from the evidence and the protocols in the participating countries.</AbstractText>Although proven beneficial only for patients with initial ventricular fibrillation (GOR A), the SSAITFTH also recommend MTH after restored spontaneous circulation, if active treatment is chosen, in patients with initial pulseless electrical activity and asystole (GOR D). Normal ethical considerations, premorbid status, total anoxia time and general condition should decide whether active treatment is required or not. MTH should be part of a standardized treatment protocol, and initiated as early as possible after indication and treatment have been decided (GOR E). There is insufficient evidence to make definitive recommendations among techniques to induce MTH, and we do not know the optimal target temperature, duration of cooling and rewarming time. New studies are needed to address the question as to how MTH affects, for example, prognostic factors.</AbstractText> |
6,872 | Epinephrine reduces cerebral perfusion during cardiopulmonary resuscitation. | Epinephrine has been the primary drug for cardiopulmonary resuscitation (CPR) for more than a century. The therapeutic rationale was to restore threshold levels of myocardial and cerebral blood flows by its alpha1 (alpha1) and alpha2 (alpha2)-adrenergic agonist vasopressor actions. On the basis of coincidental observations on changes in microvascular flow in the cerebral cortex, we hypothesized that epinephrine selectively decreases microvascular flow.</AbstractText>Randomized prospective animal study.</AbstractText>University-affiliated research laboratory.</AbstractText>Domestic pigs.</AbstractText>Four groups of five male domestic pigs weighing 40 +/- 3 kg were investigated. After induction of anesthesia, endotracheal intubation was followed by mechanical ventilation. A frontoparietal bilateral craniotomy was created. Ventricular fibrillation was induced and untreated for 3 minutes before the start of precordial compression, mechanical ventilation, and attempted defibrillation. Animals were randomized to receive central venous injections during CPR of 1) placebo, 2) epinephrine, 3) epinephrine in which both alpha1- and beta (beta)-adrenergic effects were blocked by previous administration of prazosin and propranolol, and 4) epinephrine in which both alpha2- and beta-adrenergic effects were blocked by previous administration of yohimbine and propranolol.</AbstractText>Cerebral cortical microcirculatory blood flow (MBF) was measured with orthogonal polarization spectral imaging. Cerebral cortical carbon dioxide and oxygen tensions (Pbco2 and Pbo2) were concurrently measured using miniature tissue optical sensors. Each animal was resuscitated. No differences in the number of electrical shocks for defibrillation or in the duration of CPR preceding return of spontaneous circulation were observed. Yet when epinephrine induced increases in arterial pressure, it significantly decreased Pbo2 tension and increased Pbco2 tension. Epinephrine therefore significantly decreased MBF and increased indicators of cerebral ischemia. Reduced MBF and magnified brain tissue ischemia during and after cardiopulmonary resuscitation were traced to the alpha1-adrenergic agonist action of epinephrine. When the alpha2 effects of epinephrine were blocked, reduced MBF and tissue ischemia persisted. No differences in cardiac output, end tidal Pco2, arterial Po2 and Pco2, and brain temperature were observed before inducing cardiac arrest and following return of spontaneous circulation.</AbstractText>In this model, epinephrine through its alpha1-agonist action had adverse effects on cerebral microvascular blood flow such as to increase the severity of cerebral ischemia during CPR.</AbstractText> |
6,873 | Percutaneous left ventricular assist in ischemic cardiac arrest. | Ischemic cardiac arrest represents a challenge for optimal emergency revascularization therapy. A percutaneous left ventricular assist device (LVAD) may be beneficial.</AbstractText>To determine the effect of a percutaneous LVAD during cardiac arrest without chest compressions and to assess the effect of fluid loading.</AbstractText>Totally, 16 pigs randomized to either conventional or intensive fluid with LVAD support during ventricular fibrillation (VF).</AbstractText>Acute experimental trial with pigs under general anesthesia.</AbstractText>Farm pigs of both sexes.</AbstractText>After randomization for fluid infusion, VF was induced by balloon occlusion of the proximal left anterior descending artery. LVAD and fluid were started after VF had been induced.</AbstractText>Brain, kidney, myocardial tissue perfusion, and cardiac index were measured with the microsphere injection technique at baseline, 3, and 15 minutes. Additional hemodynamic monitoring continued until 30 minutes.</AbstractText>At 15 minutes, vital organ perfusion was maintained without significant differences between the two groups. Mean cardiac index at 3 minutes of VF was 1.2 L x min(-1) x m2 (29% of baseline, p < 0.05). Mean perfusion at 3 minutes was 65% in the brain and 74% in the myocardium compared with baseline (p < 0.05), then remained unchanged during the initial 15 minutes. At 30 minutes, LVAD function was sustained in 11 of 16 animals (8 of 8 intensified fluid vs. 3 of 8 conventional fluid) and was associated with intensified fluid loading (p < 0.001).</AbstractText>During VF, a percutaneous LVAD may sustain vital organ perfusion. A potential clinical role of the device during cardiac arrest has yet to be established.</AbstractText> |
6,874 | A minimally invasive method for induction of myocardial infarction in an animal model using tungsten spirals. | Most animal models use surgical thoracotomy with ligation of a coronary artery to induce myocardial infarction. Incision of the chest wall and myocardium affect remodeling after myocardial infarction. The aim of our study was to evaluate a new minimally invasive technique for inducing acute myocardial infarction in pigs. To this end, coronary angiography using a 6-F cardiac catheter was performed in 20 pigs. The cardiac catheter was advanced into the left circumflex artery (LCX) under electrocardiographic monitoring and small tungsten spirals were deployed in the vessel. LCX occlusion was verified by coronary angiography. Two days later, magnetic resonance imaging (MRI) was performed to estimate the extent of infarction. Thereafter, all animals were euthanized and the hearts stained with 2,3,5-triphenyltetrazolium chloride for histologic measurement of infarct size. Tungsten spirals were successfully placed in the LCX in all 20 pigs. About 13 of the 20 animals survived until the end of the experiment. The mean infarct size in the area supplied by the LCX was 4.4 +/- 2.3 cm(3) at MRI and 4.3 +/- 2.2 cm(3) at histology (r = 0.99, P < 0.001). No other myocardial regions showed infarction in any of the 13 pigs. Five of nine pigs requiring defibrillation due to ventricular fibrillation died because defibrillation was unsuccessful. One animal each died from pericarditis and pneumonia. Our results show that the minimally invasive method presented here enables reliable induction of myocardial infarction in a fairly straightforward manner. The 25% mortality rate associated with induction of myocardial infarction in our study is comparable to that reported by other investigators. |
6,875 | The MUSIC Risk score: a simple method for predicting mortality in ambulatory patients with chronic heart failure. | The prognosis of chronic heart failure (CHF) is extremely variable, although generally poor. The purpose of this study was to develop prognostic models for CHF patients.</AbstractText>A cohort of 992 consecutive ambulatory CHF patients was prospectively followed for a median of 44 months. Multivariable Cox models were developed to predict all-cause mortality (n = 267), cardiac mortality (primary end-point, n = 213), pump-failure death (n = 123), and sudden death (n = 90). The four final models included several combinations of the same 10 independent predictors: prior atherosclerotic vascular event, left atrial size >26 mm/m(2), ejection fraction < or =35%, atrial fibrillation, left bundle-branch block or intraventricular conduction delay, non-sustained ventricular tachycardia and frequent ventricular premature beats, estimated glomerular filtration rate <60 mL/min/1.73 m(2), hyponatremia < or =138 mEq/L, NT-proBNP >1.000 ng/L, and troponin-positive. On the basis of Cox models, the MUSIC Risk scores were calculated. A cardiac mortality score >20 points identified a high-risk subgroup with a four-fold cardiac mortality risk.</AbstractText>A simple score with a limited number of non-invasive variables successfully predicted cardiac mortality in a real-life cohort of CHF patients. The use of this model in clinical practice identifies a subgroup of high-risk patients that should be closely managed.</AbstractText> |
6,876 | Modulation of gap junctions by nitric oxide contributes to the anti-arrhythmic effect of sodium nitroprusside? | Nitric oxide (NO) donors provide a preconditioning-like anti-arrhythmic protection in the anaesthetized dog. As NO may modulate gap junction (GJ) function, the present study investigated whether this anti-arrhythmic effect is due to a modification of GJs by NO, derived from the NO donor sodium nitroprusside (SNP).</AbstractText>In chloralose-urethane-anaesthetized, open-chest dogs, either saline (controls; n= 11) or SNP (0.2 microg x kg(-1) x min(-1); n= 10) was infused at a rate of 0.5 mL x min(-1) by the intracoronary route. The infusions were started 20 min prior to and maintained throughout the entire 60 min occlusion period of the left anterior descending coronary artery. The severity of ischaemia and of arrhythmias, tissue electrical impedance and permeability, as well as the phosphorylation of connexin43, were assessed.</AbstractText>Compared with the controls, SNP infusion markedly suppressed the total number of ventricular premature beats (666 +/- 202 vs. 49 +/- 18; P < 0.05), and the number of ventricular tachycardiac episodes (8.1 +/- 2.3 vs. 0.2 +/- 0.1; P < 0.05) without significantly modifying the incidence of ventricular tachycardia or ventricular fibrillation. The severity of ischaemia (epicardial ST-segment changes, inhomogeneity of electrical activation) and tissue electrical impedance changes were significantly less in the SNP-treated dogs. SNP improved GJ permeability and preserved the phosphorylated form of connexin43.</AbstractText>The anti-arrhythmic protection resulting from SNP infusion in the anaesthethized dog may, in part, be associated with the modulation of gap junctional function by NO.</AbstractText> |
6,877 | Improved outcomes of cardiopulmonary resuscitation in rats with myocardial infarction treated with allogenic bone marrow mesenchymal stem cells. | We hypothesized that rats in which myocardial infarction had been treated with mesenchymal stem cells (MSCs) would have better outcomes following the global myocardial ischemia of cardiac arrest and cardiopulmonary resuscitation (CPR) compared with rats in which myocardial infarction had been treated with phosphate buffer solution (PBS).</AbstractText>Prospective, randomized controlled study.</AbstractText>University-affiliated research institute.</AbstractText>Male Sprague-Dawley rats.</AbstractText>Myocardial infarction was induced in 18 male Sprague-Dawley rats. Four weeks later, animals were randomized to receive 5 x 10 MSCs labeled with red fluorescent dye gel (PKH26) in PBS or a PBS-alone injection into right femoral vein.</AbstractText>Echocardiographically measured myocardial function, including ejection fraction, left ventricular end-diastolic volume, and left ventricular end-systolic volume, was quantitated 2 and 4 weeks after administering MSCs or PBS. Four weeks after MSCs or PBS injection, 6 minutes of ventricular fibrillation (VF) and 6 minutes of CPR were performed before defibrillation. Myocardial function, including cardiac index, left ventricular, dP/dt max (dP/dt max), left ventricular negative dP/dt min (-dP/dt min), and left ventricular diastolic pressure, was measured before inducing VF and hourly following return of spontaneous circulation. Labeled MSCs were observed in 5-mum cryostat sections from each harvested heart. Significant improvements in ejection fraction, left ventricular end-diastolic volume, left ventricular end-systolic volume, cardiac index, dP/dt max, -dP/dt min, and left ventricular diastolic pressure followed injection of MSCs before inducing VF. Following return of spontaneous circulation, myocardial function was significantly better in animals pretreated with MSCs; this was associated with significantly increased duration of postresuscitation survival.</AbstractText>Myocardial function before and after CPR and duration of survival after CPR were significantly improved in animals in which myocardial infarction was treated with MSCs. MSCs existing in the myocardium resisted a secondary ischemic event and provided better postresuscitation myocardial function.</AbstractText> |
6,878 | Usefulness of body surface potential mapping for early identification of the intraventricular conduction disorders in young patients with chronic kidney disease. | Cardiovascular complications are considered a significant problem in patients with chronic kidney disease (CKD). Body surface potential mapping (BSPM) is a noninvasive method that is useful in detecting early changes involving the heart. The aim of the study was to evaluate possible abnormalities within the cardiac intraventricular conduction system in young patients with CKD using the BSPM method.</AbstractText>Based on the BSPM registrations, the QRS-T isointegral maps were created in 42 young patients with CKD (on hemodialysis, subgroup Ia; on peritoneal dialysis, subgroup Ib; on conservative treatment, group II) and in 26 healthy subjects. Serum levels of electrolytes, urea, and creatinine were also assessed in the entire study population.</AbstractText>In the healthy subjects, the maximums of the group mean QRS-T isointegral map were located in the left lower anterior part of the thorax, whereas in the Ia patients, the maximums were focused at the medial sternum line. The QRS-T maps, both for Ib and II groups, showed the positive integrals covering the left part of the anterior thorax. In all the patients with CKD, standard 12-lead electrocardiogram (ECG) and echocardiography findings were within the reference range.</AbstractText>In the hemodialyzed patients with CKD, the group-mean QRS-T isointegral map distribution suggested a significant delay of excitation propagation in the left bundle branch, although no abnormalities were found with standard ECG. In the patients with CKD treated with peritoneal dialysis or conservatively, the group-mean QRS-T isointegral maps were characteristic for the early phase of conduction disturbances within the left bundle branch, which again was not observed on the standard ECG recordings.</AbstractText> |
6,879 | Electrophysiologic changes in heart failure: focus on pacemaker channels. | Heart failure is a common clinical syndrome occurring as a result of cardiac overload, injury, and a complex interplay among genetic, neurohormonal, inflammatory, and biochemical factors. Occurrence of arrhythmias in heart failure is largely a consequence of disease-induced electrical remodeling of cardiac myocytes, a phenomenon consisting of alterations of ion channels and the ion-transport function that predispose patients to develop lethal arrhythmias. In most cases, the mechanism is the rapid onset of a ventricular tachyarrhythmia progressing to ventricular fibrillation and hemodynamic compromise. This paper highlights some of the important changes in ion channel expression and function that underlie electrical remodeling of the failing heart. Particular attention will be focused on the presence, features, and pharmacologic modulation of f channels expressed in ventricular cardiac myocytes. |
6,880 | Transient outward potassium channel regulation in healthy and diabetic hearts. | Diabetic patients have a higher incidence of cardiac arrhythmias, including ventricular fibrillation and sudden death, and show important alterations in the electrocardiogram, most of these related to the repolarization. In myocytes isolated from diabetic hearts, the transient outward K+ current (Ito) is the repolarizing current that is mainly affected. Type 1 diabetes alters Ito at 3 levels: the recovery of inactivation, the responsiveness to physiologic regulators, and the functional expression of the channel. Diabetes slows down Ito recovery of inactivation because it triggers the switching from fast-recovering Kv4.x channels to the slow-recovering Kv1.4. Diabetic animals also have decreased responsiveness of Ito towards the sympathetic nervous system; thus, the diabetic heart develops a resistance to its physiologic regulator. Finally, diabetes impairs support of various trophic factors required for the functional expression of the channel and reduces Ito amplitude by decreasing the amount of Kv4.2 and Kv4.3 proteins. |
6,881 | Activation of caspase-3 may not contribute to postresuscitation myocardial dysfunction. | We have previously reported that postresuscitation myocardial dysfunction is accompanied by the release of cytochrome c and caspase-3 activation. We now investigated the role of caspase-3 activation by examining whether such process prompts apoptotic DNA fragmentation, whether caspase-3 inhibition attenuates myocardial dysfunction, and whether myocardial protective effects of sodium-hydrogen exchanger isoform-1 (NHE-1) inhibition involve caspase-3 inhibition using a rat model of ventricular fibrillation (VF) of closed-chest resuscitation. Resuscitation after 4 or 8 min of untreated VF caused significant reductions in left ventricular stroke work index averaging 23% of sham control rats at 4 h postresuscitation. Left ventricular dysfunction was accompanied by increases in cytosolic cytochrome c, decreases in pro- and cleaved caspase-9 fragments, increases in 17-kDa caspase-3 fragments, and increases in caspase-3 activity indicating the activation of the mitochondrial apoptotic pathway but without evidence of apoptotic DNA fragmentation. In addition, levels of heat shock protein 70 were increased and levels of X-linked inhibitor of apoptosis protein and alphabeta-crystallin were preserved, all of which can exert antiapoptotic effects. In a separate series, the caspase-3 inhibitor z-Asp-Glu-Val-Asp chloromethyl ketone given before the induction of VF failed to prevent postresuscitation myocardial dysfunction despite reductions in caspase-3 activity (2.3 +/- 0.5 vs. 1.3 +/- 0.5 pmol fluorophore AFC released.mg protein(-1).min-1; P < 0.03). Treatment with the NHE-1 inhibitor cariporide had no effect on caspase-3 activity. Accordingly, in this rat model of VF and severe postresuscitation myocardial dysfunction, activation of caspase-3 did not lead to DNA fragmentation or contribute to myocardial dysfunction. Concomitant activation of intrinsic antiapoptotic mechanisms could play a protective role downstream to caspase-3 activation. |
6,882 | Assessment of nonlinear heart rate dynamics after beating-heart revascularization. | Advanced nonlinear methods of measuring heart rate variability (HRV) derived from the mathematics of complex dynamics and fractal geometry have provided new insights into the abnormalities of heart rate behavior in various pathologic conditions. These methods have provided additional prognostic information compared with traditional HRV measures and clearly have complemented the conventional linear methods. Knowledge about the behavior of complex cardiac dynamics indices after different cardiac procedures is very limited, however. We aimed to clarify how nonlinear heart rate dynamics are affected by beating-heart revascularization (off-pump coronary artery bypass graft [CABG] surgery) within the first week after the procedure.</AbstractText>Included in the study were 66 patients who had isolated stable multivessel coronary artery disease and were in normal sinus rhythm. The patients were on chronic beta-blocker therapy and were scheduled for off-pump CABG. We performed 15-minute high-resolution electrocardiographic recordings preoperatively and on the third and seventh postoperative days to assess linear and nonlinear heart rate dynamics. Frequency-domain measurements, detrended fluctuation analysis (DFA) with short-term (<or=11 beats, alpha1) and long-term (>11 beats, alpha2) correlation properties of RR-intervals, and fractal dimension (FD) measurements (average, high, and low) were made. Arrhythmia was monitored preoperatively with 24-hour Holter recordings, postoperatively by continuous monitoring for the first 4 days after the procedure, and subsequently by clinical monitoring; 24-hour Holter recordings were obtained again on the seventh postoperative day. We used the paired-samples Student t test, the Mann-Whitney U test, and the Fisher exact test for statistical analyses. Differences in arrhythmia occurrence before and after the procedure were tested with the Wilcoxon signed rank test and the McNemar test. A P level < .05 was considered statistically significant.</AbstractText>Values for all frequency-domain parameters decreased significantly after off-pump CABG (P< .001). Values for the alpha1 and high FD parameters decreased significantly after the procedure (P= .028 and .001, respectively), whereas alpha2 increased significantly (P= .023). DFA alpha1 was significantly lower in patients with postoperative atrial fibrillation than in patients remaining in sinus rhythm (mean +/- SD, 0.79+/-0.32 versus 1.13+/-0.45 [P= .003] on the third postoperative day; 0.89+/-0.31 versus 1.22+/-0.34 [P< .001] on the seventh postoperative day), whereas low and average FDs were significantly higher (1.84+/-0.16 versus 1.68+/-0.19 [P= .003] on the third postoperative day and 1.77+/-0.18 versus 1.66+/-0.17 [P= .01] on the seventh postoperative day for the low FD; 1.83+/-0.09 versus 1.76+/-0.10 [P= .011] on the third postoperative day and 1.80+/-0.11 versus 1.73+/-0.10 [P= .014] on the seventh postoperative day for the average FD). The low FD was significantly higher on the third postoperative day in patients with postoperative deterioration of ventricular ectopy than in patients with improved ventricular ectopy (1.74+/-0.17 versus 1.48+/-0.08, [P= .03]).</AbstractText>The decreases in alpha1, average FD, and high FD indicate that a profound decay of cardiac complexity and fractal correlation can be observed after off-pump CABG. Furthermore, a more extensive impairment of nonlinear indices was observed in patients who developed postoperative arrhythmias than in those who remained in stable sinus rhythm. Our findings suggest that the postoperative hyperadrenergic setting acts as a preliminary condition in which both reduced and enhanced vagal activity may predispose patients to arrhythmia, indicating that postoperative rhythm disturbances are an end point associated with divergent autonomic substrates.</AbstractText> |
6,883 | A disappearing left atrial thrombus. | The authors report a case of a migrating left atrial thrombus identified under direct visualization using transthoracic echocardiography in an elderly patient with atrial fibrillation. The left atrial-ventricular-aortic course of the thrombus was observed in real time, and prompt diagnosis and treatment of an acute cardioembolic cerebral infarction were performed. This case provides an example of the importance of transthoracic echocardiography in the diagnosis of stroke. |
6,884 | [Trends in cardiopulmonary resuscitation]. | Less than 10% of those individuals who suffer an episode of sudden cardiac arrest are successfully resuscitated and return home to live productive lives. New approaches to cardiac resuscitation could substantially improve such dismal outcome. Four current trends that have the greatest potential for improving outcome can be recognized in cardiopulmonary resuscitation (CPR): (1) systems to prevent cardiac arrests through recognition of early warning signs and timely intervention, (2) a shift towards a flow-based resuscitation emphasizing the delivery of high-quality uninterrupted CPR limiting the role of ventilation, (3) the growing role of technology in driving resuscitation interventions, incrementally enhancing the human decision-making process, and (4) the use of hypothermia. |
6,885 | Magnesium sulphate and amiodarone prophylaxis for prevention of postoperative arrhythmia in coronary by-pass operations. | The aim of this study was to investigate the use of prophylactic magnesium sulphate and amiodarone in treating arrhythmias that may occur following coronary bypass grafting operations.</AbstractText>The study population consisted of 192 consecutive patients who were undergoing coronary artery bypass grafting (CABG). Sixty-four patients were given 3 g of magnesium sulphate (MgSO4) [20 ml = 24.32 mEq/L Mg(+2)] in 100 cc of isotonic 0.9% solution over 2 hours intravenously at the following times: 12 hours prior to the operation, immediately following the operation, and on postoperative days 1, 2, and 3 (Group 1). Another group of 64 patients was given a preoperative infusion of amiodarone (1200 mg) on first post-operative day (Group 2). After the operation amiodarone was administered orally at a dose of 600 mg/day. Sixty-four patients in group 3 (control group) had 100 cc. isotonic 0.9% as placebo, during the same time periods.</AbstractText>In the postoperative period, the magnesium values were significantly higher in Group 1 than in Group 2 for all measurements. The use of amiodarone for total arrhythmia was significantly more effective than prophylactic treatment with magnesium sulphate (p = 0.015). There was no difference between the two drugs in preventing supraventricular arrhythmia, although amiodarone significantly delayed the revealing time of atrial fibrillation (p = 0.026). Ventricular arrhythmia, in the form of ventricular extra systole, was more common in the magnesium prophylaxis group. The two groups showed no significant differences in other operative or postoperative measurements. No side effects of the drugs were observed.</AbstractText>Prophylactic use of magnesium sulphate and amiodarone are both effective at preventing arrhythmia that may occur following coronary by-pass operations. Magnesium sulphate should be used in prophylactic treatment since it may decrease arrhythmia at low doses. If arrhythmia should occur despite this treatment, intervention with amiodarone may be preferable.</AbstractText> |
6,886 | Minimally invasive mitral valve surgery after previous sternotomy: experience in 181 patients. | This study evaluated the results for minimally invasive mitral valve (MV) surgery in patients who had undergone previous cardiac operations through a sternotomy.</AbstractText>From March 1, 1999 to January 2008, minimally invasive MV reoperations were performed in 181 consecutive patients (110 men) with a mean age of 64.5 +/- 12 years. A right-sided lateral minithoracotomy with femoral cannulation for cardiopulmonary bypass (CPB) was used. The principal indication was symptomatic severe mitral regurgitation (mean grade, 3.0 +/- 0.8). Previous procedures were isolated coronary bypass grafting (CABG) in 76 (42%), isolated valve operation, 55 (30%); combined CABG and valve, 16 (9%); and other cardiac operations, 34 (19%). MV replacement was previously performed in 19 patients and MV repair in 31. Mean preoperative left ventricular ejection fraction was 0.54 +/- 0.16.</AbstractText>MV repair, including repeat repair, was performed in 109 patients (60%) and MV replacement in 72 (40%). Operations were performed during ventricular fibrillation in 140 (77%), and a transthoracic aortic cross-clamp was used in 31 (17%). Ten patients (6%) underwent beating heart operations with CPB support. Mean total operating time was 176 +/- 50 min. Mean CPB time was 135 +/- 40 min. Thirty-day mortality was 6.6%. Early echocardiographic follow-up revealed excellent valve function in most patients.</AbstractText>A minimally invasive approach is a useful alternative for patients requiring a MV procedure after a previous cardiac operation, particularly in patients with patent coronary bypass grafts or previous aortic valve replacement. Very good perioperative results can be achieved with this method.</AbstractText> |
6,887 | Anesthetic management of percutaneous aortic valve implantation: focus on challenges encountered and proposed solutions. | To describe 6 months of experience in the anesthetic management of percutaneous aortic valve implantation.</AbstractText>An observational, cohort study.</AbstractText>A university hospital.</AbstractText>Eighteen high-risk patients with relative contraindications to surgical valve replacement (78 +/- 8.7 years, logistic EuroSCORE 26 +/- 19.1).</AbstractText>An Edwards/Sapien Aortic Bioprosthesis (Edwards Lifesciences LLC, Irvine, CA) was implanted in patients with severe symptomatic aortic stenosis who underwent percutaneous retrograde aortic valve implantation without cardiopulmonary bypass. The procedure was performed using general anesthesia (15 patients) or sedation (3 patients).</AbstractText>The valve was successfully implanted in all patients. One patient had prolonged ventricular fibrillation that required advanced cardiopulmonary resuscitation, endotracheal intubation, and placement of an intra-aortic balloon pump. Six patients had vascular access site complications managed either percutaneously or surgically. Five patients were extubated in the catheterization laboratory. All patients were transferred to the intensive care unit for monitoring, and all but one were discharged to an intermediate care unit within 24 hours. Early postoperative complications included acute renal failure (1 patient), arrhythmias (1 atrial fibrillation and 1 transient heart block), and stroke (1 patient). One patient died 58 days after the procedure for noncardiac reasons.</AbstractText>Transcatheter aortic valve implantation is possible in selected high-risk patients. Anesthesiologists must be aware of current technology in order to have an active role in patient selection, to develop monitoring and standards of care in the cardiac catheterization laboratory, and to plan postoperative management.</AbstractText> |
6,888 | Incremental predictive value of pre-procedural N-terminal pro-B-type natriuretic peptide for short-term recurrence in atrial fibrillation ablation. | The objective of this work was to assess the predictive value of pre-procedural N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in patients undergoing atrial fibrillation (AF) ablation. Seventy-three consecutive patients with AF (paroxysmal n = 49, persistent n = 24) and preserved left ventricular (LV) systolic function (LV ejection fraction > 45%) were prospectively enrolled in this study. All of the enrolled patients underwent catheter ablation after a measurement of their plasma NT-proBNP levels, and an echocardiographic examination with assessment of their LV diastolic function and left atrial(LA) volume. Patients with AF recurrence at 3 months had more persistent AF (P = 0.001), a higher LA volume index (P = 0.002), lesser decelerating times (DT) of mitral inflow (P = 0.014), and higher NT-proBNP levels (P < 0.001), when compared with patients with sinus rhythm restoration. The baseline log NT-proBNP correlated significantly with age (r = 0.26, P = 0.025), LA volume index (r = 0.41, P = 0.001), E/E' (r = 0.34, P = 0.007), DT (r = -0.34, P = 0.007), and E (r = 0.25, P = 0.04). The log NT-proBNP (HR 7.76, 95% CI 2.95-20.39, P < 0.001) was an independent predictor of AF recurrence. The measurement of NT-proBNP added incremental predictive value to standard indexes of LA size or diastolic function, including LA volume index and DT (P = 0.02). This study suggests the clinical utility of the level of NT-proBNP as an integrating marker of various risk factors, and as an incremental predictive marker for AF catheter ablation. |
6,889 | Development and characterization of a mouse in vitro model of ischaemia-induced ventricular fibrillation. | We sought to generate a mouse Langendorff model of ischaemia-induced ventricular fibrillation (VF) that does not depend on triggers such as programmed electrical stimulation.</AbstractText>Hearts from male Tuck Ordinary mice were perfused with Krebs solution (modified to contain low-normal K(+), 3 mmol/L, and high Ca(2+), 2.4 mmol/L) containing different combinations of catecholamines (epinephrine 313 nmol/L plus norepinephrine 75 nmol/L) and/or angiotensin II (100 pmol/L) designed to mimic the in vivo milieu. VF was absent during 30 min regional ischaemia (and during 10 min reperfusion) in Krebs-perfused hearts. Catecholamines unmasked ischaemia-induced VF (50%; P < 0.05) and reperfusion-induced VF (50%; P < 0.05). Co-perfusion with angiotensin II did not facilitate VF. Supraventricular pacing (600 b.p.m.) stabilized pre-ischaemic sinus rhythm and partially mimicked the VF-unmasking effect of catecholamines. Arrhythmia susceptibility was greatest with supraventricular pacing plus catecholamines (57% VF during ischaemia and 71% during reperfusion).</AbstractText>For the first time, regional ischaemia-induced VF was consistently evoked in a mouse Langendorff preparation, unmasked by simple periphysiological manipulation of the perfusion conditions. The model is suitable for functional genomic studies.</AbstractText> |
6,890 | Percutaneous catheter ablation of arrhythmias in children. | Supraventricular tachycardias (SVTs) are the most common arrhythmias in children, with Wolff-Parkinson-White (WPW) syndrome the most prevalent entity. Percutaneous catheter ablation is now the standard of care for SVT in pediatric patients, although specific techniques are required due to their age.</AbstractText>To evaluate the results of percutaneous catheter ablation of arrhythmias in children at our institution.</AbstractText>This was a retrospective study of the clinical records of patients aged 18 years who underwent electrophysiologic study and ablation between January 2002 and December 2006. The following variables were evaluated: demographic data, type of arrhythmia, associated structural heart disease, type of energy used, immediate and late success rate and incidence of complications.</AbstractText>During this period, 101 procedures were performed in 97 patients aged < or = 18 years. The mean age of the patients was 15.9 +/- 2.5 years (range: 7.7-18 years), and fifty-five (56.7%) were male. The arrhythmias treated were, in decreasing order of frequency: WPW syndrome (58.4%), atrioventricular reentrant tachycardia (25.7%), atrial tachycardia (5.9%), right ventricular outflow tract (RVOT) tachycardia (5%), ventricular tachycardia (2%), atrial fibrillation (2%) and frequent extrasystoles originating in the left atrium (1%). There was associated structural heart disease in six patients. Cryoablation was performed in four cases (parahisian accessory pathways in three and anterolateral accessory pathway in one). The immediate success rate was 94.1%. The six unsuccessful cases corresponded to five with parahisian accessory pathways (the procedure was not completed due to very high risk of inducing complete atrioventricular block [AVB]) and one case of RVOT tachycardia associated with arrhythmogenic right ventricular dysplasia. There were complications in two procedures (2%): one case of right bundle branch block and one of ventricular tachycardia requiring electrical cardioversion. The mean follow-up was 17.6 months. In 87.1% of cases there was clinical and ECG success on long-term followup. Three patients (3%) required repeat procedures, and were asymptomatic in later follow-up.</AbstractText>Percutaneous catheter ablation of arrhythmias in children proved to be a safe and effective treatment.</AbstractText> |
6,891 | Impact of atrial fibrillation in acute coronary syndromes. | Atrial fibrillation (AF) is a relatively common arrhythmia in the context of acute coronary syndromes (ACS). However, the impact of AF on these patients' survival is not well established. The present study aimed to estimate the prevalence of AF in ACS patients and to evaluate its impact on in-hospital and six-month post-event mortality, from any cause.</AbstractText>This was a retrospective cohort study that included 1183 patients admitted consecutively to a Coronary Care Unit with ACS. Demographic and clinical data and information from various complementary exams were collected and occurrence of AF during the first 48 hours of hospitalization was analyzed. Six-month follow-up was achieved in 95.9% of the patients. Logistic regression statistical analysis was used to identify independent predictors of in-hospital and six-month post-event mortality.</AbstractText>AF was diagnosed in 140 patients (11.8%); these patients were older (73.89 +/- 8.69 vs. 63.20 +/- 12.73 years; p<0.0001) and less likely to be male (60.0% vs. 74.1%; p=0.001), and had a lower prevalence of dyslipidemia (32.9% vs. 44.1%; p=0.001) and smoking (10.0% vs. 25.9%; p<0.0001). Fewer patients with AF underwent reperfusion therapy (19.3% vs. 29.7%; p=0.006), beta-blocker therapy (72.1% vs. 85.7%; p<0.0001), and cardiac catheterization (48.2% vs. 62.9%; p=0.001) or percutaneous coronary intervention (14.3% vs. 23.4%; p=0.01). These patients more frequently developed heart failure (54.3% vs. 28.5%; p<0.0001) and more often presented left ventricular dysfunction (69.3% vs. 57.2%; p=0.002). In patients presenting AF, there were significant increases in in-hospital (12.1% vs. 4.2%; p<0.0001) and six-month mortality (27.2% vs. 8.2%. p<0.0001). In multivariate analysis, AF remained an independent marker of in-hospital (OR 1.95; 95% CI 1.03-3.69; p=0.03) and six-month mortality (OR 2.89; 95% CI 1.67-5.00; p=0.0001), as was age >75 years, severe left ventricular dysfunction and heart failure. The performance of coronary angiography correlated with improved prognosis.</AbstractText>AF in the context of ACS is an independent predictor of increased in-hospital and six-month mortality. These findings should be taken into consideration in the management and treatment of such patients.</AbstractText> |
6,892 | The incidence and risk factors of arrhythmias in the early period after cardiac surgery in pediatric patients. | Rhythm disturbances that develop after pediatric surgery for heart disease significantly increase mortality and morbidity risk. The aim of this study was to determine incidence rates of different arrhythmias and identify risk factors for these disturbances in this patient group. The study involved 580 children in the pediatric cardiovascular intensive care unit who had undergone cardiac surgery between May 2001 and December 2002. Each was followed until discharge. The patient who sustained arrhythmia was recorded. Fifty-one of the patients (8.8%, mean age 1.7+/-2.3 years) developed arrhythmias. Twenty-one (41.1%) had supraventricular tachycardia, 12 (23.5%) had junctional ectopic tachycardia, 10 (19.6%) had complete atrioventricular block, 3 (5.8%) had ventricular arrhythmias, and 5 (9.8%) had atrial fibrillation and atrioventricular dissociation. There was a trend toward higher incidence of arrhythmia (rate, 43.1%) in the 0-6 months age group. The incidence rates of arrhythmia after certain procedures were as follows: 75% after Rastelli operation, 16.7% after total anomalous pulmonary venous return repair, 13.8% after ventricular septal defect repair, 12.8% after the arterial switch operation or arterial switch with ventricular septal defect closure for transposition of the great arteries, 12.5% after atrioventricular septal defect repair, 12.1% after total correction of tetralogy of Fallot, 9.1% after bidirectional cava-pulmonary connection and Fontan procedure, and 6.6% after other miscellaneous procedures. The mean cardiopulmonary bypass time was 105.4+/-54.1 min. At the time of arrhythmia appearance, the mean values for electrolyte (sodium 144+/-5 mEq/L, potassium 3.78+/-0.91 mEq/L, ionized calcium 1.15+/-0.33 mmol/L) and arterial blood gas parameters (pH 7.40+/-0.12 and HCO3 24.7+/-6.3 mmol/L) were all in the normal range. Fifteen (29.4%) of the patients with arrhythmias died and in 7 of these cases, the death was directly linked to resistant arrhythmia. Arrhythmias can be life-threatening especially in the early period after pediatric heart surgery. The incidence of arrhythmia in this series was 8.8%. The results identified type of operation as a major risk factor for arrhythmia after pediatric heart surgery and they also suggest that age may be important as well. |
6,893 | Modulation of the sinus rate during ventricular fibrillation. | During supraventricular and ventricular tachycardia, the arterial baroreflex predominates with minimal contribution from the cardiopulmonary reflex. To our knowledge, the role of the arterial baroreflex gain (BRG) during and immediately following termination of ventricular fibrillation (VF) has not been characterized.</AbstractText>We hypothesized that (1) arterial BRG correlated with sinus node cycle length (SNCL) changes during VF, and that (2) the greater the arterial BRG, the greater the blood pressure (BP) recovery following successful defibrillation.</AbstractText>Arterial BRG was assessed in 18 patients referred for the implantation of a defibrillator incorporating an atrial lead. The average SNCL was measured during the 5 seconds prior to VF induction and the last 5 seconds during VF before defibrillation. Percent SNCL change (%DeltaSNCL) was determined. Arterial BP recovery was calculated as the difference in mean BP following defibrillation compared to during VF.</AbstractText>Arterial BRG ranged between -3 and 18 ms/mmHg. During VF, SNCL shortened in 11 patients (group A, mean %DeltaSNCL =-15%), and surprisingly lengthened in seven patients (group B, mean %DeltaSNCL = 5%). There was no correlation between %DeltaSNCL and arterial BRG. In fact, arterial BRG in group A was lower when compared with group B (P = 0.075). Similarly, there was no correlation between arterial BRG and BP recovery.</AbstractText>We found no correlation between arterial BRG and %DeltaSNCL during VF, or BP recovery following defibrillation. Our findings of SNCL lengthening in 7 of 18 patients suggest that in some patients, arterial BRG plays a minor role during VF with a greater contribution from the cardiopulmonary BRG.</AbstractText> |
6,894 | Gene Variant of the Bradykinin B2 Receptor Influences Pulmonary Arterial Pressures in Heart Failure Patients. | BACKGROUND: Pulmonary arterial pressure (PAP) varies considerably in heart failure (HF) despite similar degrees of left ventricular (LV) dysfunction. Bradykinin alters vascular tone and common variations in the kinin B2 receptor (BDKRB2) gene exists. We hypothesized that genetic variation in this receptor would influence PAP in HF. METHODS: 131 HF patients (>1yr history systolic HF), without COPD, not currently smoking, BMI < 40, without atrial fibrillation completed the study which included a blood draw for genotyping and neurohormones (ACE, A-II, Bradykinin, ANP, BNP, and catecholamines), an echocardiogram for cardiac function and systolic PAP (PAPsys). RESULTS: Mean LVEF was 29% ± 12%, NYHA class 2 ± 1, age 56 ± 12 yr, BMI 28 ± 5 kg/m(2). Forty-six patients (35%) were homozygous for the +9 allele, 58 (44%) were heterozygous (+9/-9) and 27 (21%) were homozygous for the -9 allele of the BDKRB2. PAPsys averaged 42 ± 13, 38 ± 12, and 35 ± 11 mmHg for +9/+9, +9/-9 and -9/-9, respectively (p = 0.03). There was a trend towards gene effect for plasma ACE with the highest values in +9/+9 and lowest in -9/-9 patients (9.5 ± 10.7, 7.1 ± 8.7, and 5.4 ± 6.4 U/L, respectively, p = 0.06). There were no differences in plasma bradykinin or A-II, LVEF, or NYHA across genotypes. CONCLUSION: These data suggest the +9/+9 polymorphism of the BDKRB2 receptor influences pulmonary vascular tone in stable HF. |
6,895 | Remote implantable cardioverter defibrillator monitoring in a Brugada syndrome population. | The diagnosis of Brugada syndrome (BS) is typically made in a young and otherwise healthy population. In patients with a high risk of sudden cardiac death (SCD), the only currently recommended therapy is an implantable cardioverter defibrillator (ICD), but these are not without complications. We investigated whether remote ICD monitoring could simplify follow-up and detect potential complications in these patients.</AbstractText>Thirty-five consecutive patients (26 males, 44 +/- 11 years) implanted with an ICD for BS with a remote monitoring ['Home Monitoring' (HM), Biotronik, Germany] system were prospectively enrolled in this study. They were matched for age, sex, and follow-up duration with 35 BS patients implanted with an ICD without this capability. During a mean follow-up of 33 +/- 17 months, the number of cardiology consultations was significantly lower in the HM group (3 +/- 2 vs. 7 +/- 3; P < 0.001). Inappropriate shock(s) [IS(s)] occurred in three patients (8.5%) in the HM group vs. six (17%) in the control group (P = NS). Ten patients in the HM group had a median of four alerts ('ventricular tachycardia/ventricular fibrillation detection' in all patients, 'shock' in three, 'ineffective shock' in two patients with shock on noise, 'extreme ventricular pacing impedance' in one patient due to lead failure, and 'deactivated therapy' in two patients with lead failure before replacement). In 5 of these 10 patients, prompt reprogramming of the ICD may have prevented IS(s).</AbstractText>Remote ICD monitoring in patients with BS decreases outpatient consultations and may help prevent ISs.</AbstractText> |
6,896 | Synchronization of chaotic early afterdepolarizations in the genesis of cardiac arrhythmias. | The synchronization of coupled oscillators plays an important role in many biological systems, including the heart. In heart diseases, cardiac myocytes can exhibit abnormal electrical oscillations, such as early afterdepolarizations (EADs), which are associated with lethal arrhythmias. A key unanswered question is how cellular EADs partially synchronize in tissue, as is required for them to propagate. Here, we present evidence, from computational simulations and experiments in isolated myocytes, that irregular EAD behavior is dynamical chaos. We then show in electrically homogeneous tissue models that chaotic EADs synchronize globally when the tissue is smaller than a critical size. However, when the tissue exceeds the critical size, electrotonic coupling can no longer globally synchronize EADs, resulting in regions of partial synchronization that shift in time and space. These regional partially synchronized EADs then form premature ventricular complexes that propagate into recovered tissue without EADs. This process creates multiple premature ventricular complexes that propagate as [corrected] "shifting" foci resembling polymorphic ventricular tachycardia. Shifting foci encountering shifting repolarization gradients can also develop localized wave breaks leading to reentry and fibrillation. As predicted by the theory, rabbit hearts exposed to oxidative stress (H(2)O(2)) exhibited multiple shifting foci causing polymorphic tachycardia and fibrillation. This mechanism explains how collective cellular behavior integrates at the tissue scale to generate lethal cardiac arrhythmias over a wide range of heart rates. |
6,897 | [Long QT syndrome: an underestimated cause of sudden infant death]. | Congenital long QT syndrome (LQTS) is an inherited arrhythmia that can be sporadic or familial. It predisposes to sudden cardiac death by ventricular fibrillation, which can occur at any age, particularly in neonates. Recent postmortem molecular screening surveys have shown that 10 to 12% of sudden infant death syndrome (SIDS) cases were potentially related to congenital long QT syndrome. Current SIDS etiological surveys fail to diagnose LQTS. Specific questioning and electrocardiographic screening of first-degree relatives could greatly facilitate LQTS diagnosis. We propose adding these to screening modalities after a SIDS incident. Neonatal electrocardiographic screening could allow early identification of LQTS and adapted treatment and follow-up. |
6,898 | Acute ischemic heart disease alters ventricular fibrillation waveform characteristics in out-of hospital cardiac arrest. | Although ventricular fibrillation waveform characteristics (VFWC) correlate with coronary perfusion pressure and may predict defibrillation outcome, recent animal data indicate that these waveform characteristics are altered in both acute myocardial infarction (AMI) and chronic coronary heart disease (CHD). We wanted to confirm these recent animal data in humans and explore the possibility for such characteristics to identify acute ischemia during cardiac arrest.</AbstractText>Data from all adult patients admitted to hospital after out-of-hospital VF cardiac arrest in Oslo between May 2003 and July 2007 were prospectively collected. Patients were categorized into one of four pre-defined etiologic groups: patients with AMI (AMI only), patients with AMI and CHD (AMI and CHD), patients with previous CHD without evidence for a new AMI (CHD only), and patients with primary arrhythmia (PA). VFWC were analyzed from prehospital ECG tracings, and the different etiologic groups compared using ANOVA.</AbstractText>One-hundred-and-one patients with ECG recordings usable for VF analysis could confidently be categorized; 16 with AMI only, 34 with AMI and CHD, 41 with CHD only and 10 with PA. The two VFWC median slope (MS) and amplitude spectral area (AMSA) were significantly depressed in patients with AMI only compared to both PA (MS p=0.008, AMSA p=0.035) and CHD only patients (MS p=0.008, AMSA p=0.006).</AbstractText>AMI patients have depressed MS and AMSA compared to patients without AMI during VF cardiac arrest. VFWC might be helpful in identifying patients with AMI during cardiac arrest, but prospective clinical studies are warranted to assess its feasibility and clinical benefit.</AbstractText> |
6,899 | Characteristics of recurrent ventricular fibrillation associated with inferolateral early repolarization role of drug therapy. | Our purpose was to evaluate the efficacy of antiarrhythmic drugs (AADs) in recurrent ventricular fibrillation (VF) associated with inferolateral early repolarization pattern on the electrocardiogram.</AbstractText>Although an implantable cardioverter-defibrillator is the treatment of choice, additional AADs may be necessary to prevent frequent episodes of VF and reduce implantable cardioverter-defibrillator shock burden or as a lifesaving therapy in electrical storms.</AbstractText>From a multicenter cohort of 122 patients (90 male subjects, age 37 +/- 12 years) with idiopathic VF and early repolarization abnormality in the inferolateral leads, we selected all patients with more than 3 episodes of VF (multiple) including those with electrical storms (> or =3 VF in 24 h). The choice of AAD was decided by individual physicians. Follow-up data were obtained for all patients using monitoring with implantable defibrillator. Successful oral AAD was defined as elimination of all recurrences of VF with a minimal follow-up period of 12 months.</AbstractText>Multiple episodes of VF were observed in 33 (27%) patients. Electrical storms (34 +/- 47 episodes) occurred in 16 and were unresponsive to beta-blockers (11 of 11), lidocaine/mexiletine (9 of 9), and verapamil (3 of 3), while amiodarone was partially effective (3 of 10). In contrast, isoproterenol infusion immediately suppressed electrical storms in 7 of 7 patients. Over a follow-up of 69 +/- 58 months, oral AADs were poorly effective in preventing recurrent VF: beta-blockers (2 of 16), verapamil (0 of 4), mexiletine (0 of 4), amiodarone (1 of 7), and class 1C AADs (2 of 9). Quinidine was successful in 9 of 9 patients, decreasing recurrent VF from 33 +/- 35 episodes to nil for 25 +/- 18 months. In addition, quinidine restored a normal electrocardiogram.</AbstractText>Multiple recurrences of VF occurred in 27% of patients with early repolarization abnormality and may be life threatening. Isoproterenol in acute cases and quinidine in chronic cases are effective AADs.</AbstractText> |
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