Current practice of ventricular tachycardia ablation in patients with implantable cardioverter-defibrillators.

We performed a survey on current practice of ventricular tachycardia (VT) ablation in patients with implantable cardioverter-defibrillators among the European Heart Rhythm Association Research Network. The main indication for the procedure is the occurrence of multiple shocks or electrical storm, while prophylactic ablation is only rarely performed. The epicardial approach is seldom used and mostly only after failure of endocardial ablation. The main ablation strategy is targeting the clinical VT only by substrate mapping and ablation, and by targeting fractionated potentials with utilization of modern electroanatomical mapping systems. Still, a considerable number of centres frequently perform the procedure using conventional mapping catheters only.

Cushion bearings versus large diameter head metal-on-metal bearings in total hip arthroplasty: a short-term metal ion study.

INTRODUCTION: Metal-on-metal total hip arthroplasty (MOM THA) has the advantage of replicating the femoral head size, but the postoperative elevation of serum metal ion levels is a cause for concern. Metal-on-polycarbonate-urethane is a new cushion bearing featuring a large diameter metal head coupled with a polycarbonate-urethane liner. AIM: The aim of this study was to assess and compare serum cobalt (Co) and chromium (Cr) levels in a group of 15 patients treated with a cushion bearing THA system (Group A) and a group of 15 patients treated with a MOM THA system (Group B) at short-term. At a mean follow-up of 27.3 months (18-35 months), in Group A the median Cr and Co serum levels were significantly lower than in Group B, measuring 0.24 µg/L (0.1-2.1 µg/L) and 0.6 µg/L (0.29-2.3 µg/L) compared to 1.3 µg/L (0.1-9 µg/L, p < 0.001) and 2.9 µg/L (0.85-13.8 µg/L, p < 0.001) respectively. RESULTS: All patients demonstrated an excellent clinical result, as shown by the Harris and Oxford hip scores. The cushion bearing THA studied in this paper showed clinical outcomes similar to the MOM THA bearing, with the advantage of no significant metal ion elevation in the serum. CONCLUSION: These findings warrant the continued clinical study of compliant bearing options.

CArdiac resynchronization in combination with beta blocker treatment in advanced chronic heart failure (CARIBE-HF): the results of the CARIBE-HF study.

OBJECTIVE: Cardiac resynchronization therapy (CRT), combined with optimal medical therapy (OMT), is an established treatment for patients with advanced chronic heart failure (ACHF). In ACHF, carvedilol at the dose used in clinical trials, reduces morbidity and mortality. However, patients often do not tolerate the drug at the targeted dosage. The aim of the CARIBE-HF prospective observational study was to investigate the role of CRT in the implementation of carvedilol therapy in patients with ACHF. METHODS: One hundred and six patients (aged 65 12 [mean +/- SD] years) with ACHF were enrolled and treated with OMT, in which carvedilol was titrated up to the maximal dose (phase 1). Subsequently, patients with left ventricular (LV) ejection fraction < or = 35%, NYHA class III-IV and QRS interval > or =120 msec were assigned to CRT. Both CRT and NO-CRT patients underwent a long-term follow-up of 7 years (1193.98 +/- 924 days), while efforts to up titrate the carvedilol dose were continued during the second phase (471 + 310 days). Phase 1 was completed by 84 patients (79%), and 15 (18%) underwent CRT. The mean carvedilol dose in the CRT group was 19.0 +/- 17.8 mg, against 32.7 +/- 19.1 mg in the remaining 69 patients (P = 0.018). At the end of phase 2, CRT patients presented a significantly greater variation of increasing in the carvedilol dose than NO-CRT patients (+20.0 +/- 19.8 mg vs. -0.3 +/- 20.5 mg; P = 0.015), a greater NYHA class reduction (-0.8 +/- 0.6 vs. -0.2 +/- 0.7; P = 0.011), and a greater increase in LV ejection fraction (10.8 +/- 9 vs. 3.1 +/- 6.1; P = 0.018). CONCLUSIONS: The data from the CARIBE study suggest that, in ACHF, CRT may be effective in enabling the target dose of carvedilol to be reached. The significant improvement seen in LV function was probably due to a synergistic effect of CRT and carvedilol. During the extended follow-up (mean 1193.98 +/- 924 days) the mean dosage of carvedilol in the CRT group was significantly higher (P < 0.02).

Safety and performance of a system specifically designed for selective site pacing.

INTRODUCTION: In the right ventricle, selective site pacing (SSP) has been shown to avoid detrimental hemodynamic effects induced by right ventricular apical pacing and, in the right atrium, to prevent the onset of atrial fibrillation and to slow down disease progression. The purpose of our multicenter observational study was to describe the use of a transvenous 4-French catheter-delivered lead for SSP in the clinical practice of a large number of centers. METHODS: We enrolled 574 patients in whom an implantable device was indicated. In all patients, SSP was achieved by using the Select Secure System™ (Medtronic Inc., Minneapolis, MN, USA). RESULTS: In 570 patients, the lead was successfully implanted. In 125 patients, atrial SSP was performed: in 75 (60%) the lead was placed in the interatrial septum, in 31 (25%) in the coronary sinus ostium, and in 19 (15%) in the Bachman bundle. Ventricular SSP was undertaken in 138 patients: in 105 (76%) the high septal right ventricular outflow tract (RVOT) position was paced, in seven (5%) the high free-wall RVOT, in 25 (18%) the low septal RVOT, and in one (1%) the low free-wall RVOT. In the remaining 307 patients, the His zone was paced: in 87 (28%) patients, direct His-bundle pacing and in 220 (72%) patients para-hisian pacing was achieved. Adequate pacing parameters and a lead-related complication rate of 2.6% were recorded during a follow-up of 20 ± 10 months. CONCLUSIONS: Our results demonstrated that many sites, in the right atrium, in the right ventricle, and in His-bundle region, can be paced using the Select Secure System™.

Remote monitoring for active cardiovascular implantable electronic devices: a European survey.

This survey sampled today's European practices in the use of remote monitoring (RM) for the follow-up of active cardiovascular implantable electronic devices. Eighty-five per cent of the responding centres are currently using RM. For the majority, RM is expected to increase importantly within 5 years, and it has already led to a new organization of care based on dedicated allied professionals and/or the creation of RM units. There are still major limitations for the development of RM, such as ethical and legal aspects, reimbursement issues, and the lack of specific national- and European-updated guidelines which need to be informed.

Sudden cardiac death stratification in asymptomatic ventricular preexcitation.

The second survey deals with risk stratification in subjects, either adults or children, with ventricular preexcitation and no symptoms in their history. Current European electrophysiological practice is still variable among different centres. Although invasive stratification is still part of the practical management of asymptomatic subjects, a not negligible proportion of physicians do not completely rely on cut off values provided in the literature, proceeding to ablation irrespective of the stratification process. These concerns are mainly due to the perception of lack of strong evidence that, according to the majority of centres, is still needed.

Ablate and pace as bail-out therapy in a patient with Fontan correction and malignant atrial tachycardia.

Atrial tachyarhthmias complicating Fontan correction may have a 'malignant' clinical presentation seriously impairing the patient haemodynamic. Current strategies are surgical total cavopulmonary connection with or without antiarrhythmic surgery or transcatheter ablation. We describe the case of a patient who previously underwent atriocaval Fontan correction and later presented with refractory atrial tachycardia responsible for relapsing syncope. After a failed attempt at surgical conversion, and while waiting for heart transplantation, he was submitted to ablation of the atrioventricular node through an aortic retrograde approach and ventricular pacing through the coronary sinus tree. One year later, the patient is doing well, displaying a stable functional recovery and excellent pacing lead performances. An ablate and pace approach may deserve consideration in selected Fontan patients experiencing life-threatening atrial arrhythmias.

Selective-site pacing in paediatric patients: a new application of the Select Secure system.

AIMS: The aim of this study was to evaluate the feasibility and reliability of selective-site pacing by means of a new lead system in a paediatric population. This lead system is composed of a 4.1 Fr, active-fixation lead and a steerable catheter that allows easy positioning in selective sites. METHODS AND RESULTS: Thirty young patients (mean age 9.0 +/- 4.5 years, range 2-16 years) received a single- (10) or dual- (20) chamber pacemaker. The 3830 lead was implanted successfully in the targeted chambers in all patients. The selective RV sites of pacing in 26 of the patients were: 18 mid-septum, 5 outflow tract, 1 low-septum, and 2 LEVO-RV-Apex. In all patients, an intracardiac loop was left in order to avoid stretching of the lead with growth. Mean follow-up duration was 11 +/- 10 months. Atrial sensing and pacing thresholds were 3.2 +/- 1.7 mV and 0.8 +/- 0.6 V at 0.5 ms at implantation and 3.4 +/- 2.1 mV and 0.6 +/- 0.3 V at 0.5 ms at follow-up. Ventricular sensing and pacing thresholds were 12.1 +/- 4.9 and 0.7 +/- 0.4 V at 0.5 ms on implantation and 12.7 +/- 6.1 mV and 0.8 +/- 0.5 V at 0.5 ms at follow-up (P = NS). No adverse events were reported. CONCLUSION: Select Secure is a promising system for selective-site pacing in children.

Performance and survival of transvenous defibrillation leads: need for a European data registry.

Although the use of implantable cardioverter defibrillator (ICD) therapy has increased over the last decades, the reporting of ICD lead performance is inadequate. So far, there is neither a European nor worldwide registry on ICD leads. The published long-term results from national or multicentre registries encompass relatively small patient cohorts. Nevertheless, the failure of ICD leads may have substantial clinical consequences, including failure to sense, failure to pace, failure to defibrillate, inappropriate shocks, and even death of the patient. The reported ICD lead survival varies significantly between studies: 91-99% at 2 years, 85-95% at 5 years, and 60-72% at 8 years. Thus, the true incidence of lead malfunction cannot be defined as outlined in the present review. One current initiative of the European Heart Rhythm Association is to initiate and develop a Europe-wide registry to monitor, over a prolonged follow-up period, the performance of ICDs and ICD leads.

Clinical experience with a single catheter for mapping and ablation of pulmonary vein ostium.

INTRODUCTION: The aim of this single center study is to evaluate the safety and the efficacy of performing pulmonary vein isolation (PVI) using a single high-density mesh ablator (HDMA) catheter. METHODS: A total of 17 consecutive patients with paroxysmal (10 patients) or persistent atrial fibrillation (7 patients) and no heart disease were enrolled. A single transseptal puncture was performed and the HDMA was placed at each PV ostium identified with anatomic and electrophysiological mapping. Pulsed radiofrequency (RF) energy was delivered at the targeted temperature of 58 degrees C with maximum power of 80 watts. No other ablation system was utilized. The primary objective of the study was acute isolation of the targeted PV, and the secondary objective was clinical efficacy and safety of PVI with HDMA for atrial fibrillation (AF) prevention. Patients were followed at intervals of 1, 3, 6, and 12 months. RESULTS: PVI was attempted with HDMA in 67/67 PVs. [Correction made after online publication October 27, 2008: PVs changed from 6/67 to 67/67] Acute success rate were: 100% (16/16) for left superior PV, 100% (16/16) for left inferior PV, 100% (17/17) for right superior PV, 100% (1/1) for left common trunk and 47% (8/17) for right inferior PV. Total procedure time was 200 +/- 36 minutes (range 130-240 minutes) and total fluoroscopy time was 42 +/- 18 minutes (range 23-75 minutes). During a mean follow-up of 11 +/- 4 months, 64% of patients remained in sinus rhythm (8/10 paroxysmal AF and 3/7 for persistent AF). No complications occurred either acutely or at follow-up. CONCLUSIONS: PV isolation with HDMA is feasible and safe. The midterm efficacy in maintaining sinus rhythm is higher in paroxysmal than in persistent patients.

Malignant perinatal variant of long-QT syndrome caused by a profoundly dysfunctional cardiac sodium channel.

BACKGROUND: Inherited cardiac arrhythmia susceptibility contributes to sudden death during infancy and may contribute to perinatal and neonatal mortality, but the molecular basis of this risk and the relationship to genetic disorders presenting later in life is unclear. We studied the functional and pharmacological properties of a novel de novo cardiac sodium channel gene (SCN5A) mutation associated with an extremely severe perinatal presentation of long-QT syndrome in unrelated probands of different ethnicity. METHODS AND RESULTS: Two subjects exhibiting severe fetal and perinatal ventricular arrhythmias were screened for SCN5A mutations, and the functional properties of a novel missense mutation (G1631D) were determined by whole-cell patch clamp recording. In vitro electrophysiological studies revealed a profound defect in sodium channel function characterized by approximately 10-fold slowing of inactivation, increased persistent current, slowing of recovery from inactivation, and depolarized voltage dependence of activation and inactivation. Single-channel recordings demonstrated increased frequency of late openings, prolonged mean open time, and increased latency to first opening for the mutant. Subjects carrying this mutation responded clinically to the combination of mexiletine with propranolol and survived. Pharmacologically, the mutant exhibited 2-fold greater tonic and use-dependent mexiletine block than wild-type channels. The mutant also exhibited enhanced tonic (2.4-fold) and use-dependent block ( approximately 5-fold) by propranolol, and we observed additive effects of the 2 drugs on the mutant. CONCLUSIONS: Our study demonstrates the molecular basis for a malignant perinatal presentation of long-QT syndrome, illustrates novel functional and pharmacological properties of SCN5A-G1631D, which caused the disorder, and reveals therapeutic benefits of propranolol block of mutant sodium channels in this setting.

Fast-slow and slow-slow form of atrioventricular nodal reentrant tachycardia sustained by the same reentrant circuit: a case report.

It has been suggested that a reentrant circuit confined to the posterior extensions of the atrioventricular node underlies both fast-slow and slow-slow types of atrioventricular nodal reentrant tachycardia (AVNRT). According to this hypothesis the fast-slow reentrant circuit would be formed by two slow pathways, located in the rightward and leftward posterior extension of the atrioventricular node. Thus, the fast pathway would act as a bystander with respect to the reentrant circuit. We describe the case of a 40-year-old woman with several episodes of palpitations unresponsive to antiarrhythmic drugs. The ECG during symptoms showed a narrow QRS tachycardia with a long ventriculo-atrial interval and a negative P wave in the inferior leads. Electrophysiological study showed the inducibility of a slow-slow AVNRT which rapidly shifted to a fast-slow AVNRT without any change in the duration of the tachycardia cycle. Our observation is in agreement with the hypothesis that the fast-slow reentrant circuit consists of two slow pathways with the fast pathway acting as a bystander.

Periodic conduction and 2:1 block from the left atrium to the pulmonary vein during radiofrequency ablation.

Paroxysmal atrial fibrillation is often initiated by foci in the pulmonary veins (PVs); the junction between the PVs and the left atrium (LA) has become the target of radiofrequency (RF) ablation performed to isolate the PVs. Ectopic atrial beats originating from the PVs propagate to the LA with a characteristically long conduction time, often with a conduction delay or block within the PV or at the PV-LA junction. However, details about the conduction properties within the PVs and across the PV-LA junction are still scanty. We report a unique case of LA-PV decremental conduction caused by RF applications. New insights into the electroanatomical characteristics of the PV-LA junction are provided. The present report demonstrates, for the first time in humans, that decremental conduction may be related to the progressive damage of the conducting myocardial bundle due to RF energy applications.

The role of invasive electrophysiology in the management of patients with chronic heart failure.

It is well known that both atrial and ventricular arrhythmias play a key role in morbidity and overall mortality among patients with heart failure. In addition to pharmacological treatment, up-to-date and evidence-based use of invasive electrophysiology, including implantable cardioverter defibrillator implantation, is recommended in the global management of patients with heart failure. This article will review current clinical indications for invasive electrophysiology, either acknowledged or under evaluation, focusing on the scientific background and some technical and practical aspects. The discussion is organized in an arrhythmia-based manner so that ventricular-, atrial-, and heart transplant-related arrhythmias will be discussed separately.