The point on the treatment of arrhythmic storm.

Arrhythmic storm is a clinical emergency associated with high mortality, which requires multi-disciplinary management. Reprogramming of the implantable cardiac defibrillator (ICD) aimed at reducing shocks, adrenergic blockade using beta-blockers, sedation/anxiolysis, and blockade of the stellate ganglion represent the first simple and effective manoeuvres, but further suppression of arrhythmias with antiarrhythmics is often required. A low-risk patient (e.g. monomorphic ventricular tachycardia, functioning ICD, and haemodynamically stable) should be managed with a beta-blocker (possibly non-selective) plus amiodarone, in addition to sedation with a benzodiazepine or dexmedetomidine; in patients at greater risk (high burden and haemodynamic instability), autonomic modulation with blockade of the stellate ganglion and the addition of a second antiarrhythmic (lidocaine) should be considered. In patients refractory to these measures, with advanced heart failure, general anaesthesia with intubation and the establishment of a haemodynamic circulatory support should be considered. Ablation, performed early, appears to be superior in terms of mortality and reduction of future shocks compared with titration of antiarrhythmics.

Safety, efficacy, and reproducibility of cavotricuspid isthmus ablation guided by the ablation index: acute results of the FLAI study.

AIMS: Ablation index (AI) is a marker of lesion quality during catheter ablation that incorporates contact force, time, and power in a weighted formula. This index was originally developed for pulmonary vein isolation as well as other left atrial procedures. The aim of our study is to evaluate the feasibility and efficacy of the AI for the ablation of the cavotricuspid isthmus (CTI) in patients presenting with typical atrial flutter (AFL). METHODS AND RESULTS: This prospective multicentre non-randomized study enrolled 412 consecutive patients with typical AFL undergoing AI-guided cavotricuspid isthmus ablation. The procedure was performed targeting an AI of 500 and an inter-lesion distance measurement of ≤6 mm. The primary endpoints were CTI 'first-pass' block and persistent block after a 20-min waiting time. Secondary endpoints included procedural and radiofrequency duration and fluoroscopic time. A total of 412 consecutive patients were enrolled in 31 centres (mean age 64.9 ± 9.8; 72.1% males and 27.7% with structural heart disease). The CTI bidirectional 'first-pass' block was reached in 355 patients (88.3%), whereas CTI block at the end of the waiting time was achieved in 405 patients (98.3%). Mean procedural, radiofrequency, and fluoroscopic time were 56.5 ± 28.1, 7.8 ± 4.8, and 1.9 ± 4.8 min, respectively. There were no major procedural complications. There was no significant inter-operator variability in the ability to achieve any of the primary endpoints. CONCLUSION: AI-guided ablation with an inter-lesion distance ≤6 mm represents an effective, safe, and highly reproducible strategy to achieve bidirectional block in the treatment of typical AFL.

Ablation therapy for ventricular arrhythmias in patients with LVAD: Multiple faces of an electrophysiological challenge.

Left ventricular assist device implantation is a recognized treatment option for patients with advanced heart failure refractory to medical therapy and can be used both as bridge to transplantation and as destination therapy. The risk of ventricular arrhythmias is common after left ventricular assist device implantation and is influenced by pre-, peri and post-operative determinants. The management of ventricular arrhythmias can be a challenge when they become refractory to medication or to device therapy and their impact on prognosis can be detrimental despite the mechanical support. In this setting, catheter ablation is being increasingly recognized as a feasible option for patients in which standard therapeutic strategies fail, but also with preventive purpose. Catheter ablation is being increasingly considered for the management of ventricular arrhythmias in patients with left ventricular assist device despite complex clinical and technical peculiarities due to the characteristics of the mechanical support. Much conflicting data exist regarding the predictors of success of the procedure and the rate of recurrence. In this review we discuss the latest evidences regarding catheter ablation of ventricular arrhythmias in this subset of patients, focusing on clinical characteristics, arrhythmia etiology, technical aspects and postprocedural features which must be considered by the electrophysiologist.

Effective nonapical left ventricular pacing with quadripolar leads for cardiac resynchronization therapy.

BACKGROUND: Current guidelines recommend avoiding apical left ventricular (LV) pacing for cardiac resynchronization therapy (CRT). AIMS: We investigated the feasibility of nonapical pacing with the current quadripolar LV lead technology. METHODS: We analyzed consecutive patients who received CRT with an LV quadripolar lead. The post--implantation position of each electrode of the LV lead was designated as basal, mid, or apical. The pacing capture threshold (PCT) and phrenic nerve stimulation (PNS) threshold were assessed for each electrode. RESULTS: We enrolled 168 patients. A total of 8 CRT defibrillators were from Biotronik (with Sentus OTW QP leads), 98 were from Boston Scientific (with 21 Acuity X4 Spiral and 77 Acuity X4 Straight leads), and 62 from St. Jude Medical (with Quartet leads). The median (interquartile range) number of electrodes at nonapical segments per patient was 3 (1-4) with Biotronik Sentus leads, 4 (3-4) with spiral -design Boston Scientific leads, 4 (3-4) with straight Boston Scientific leads, and 3 (3-4) with St. Jude Medical Quartet leads (P = 0.045). Three patients (38%) with Biotronik Sentus leads, 21 (100%) with spiral -design Boston Scientific leads, 69 (90%) with straight -design Boston Scientific leads, and 49 (79%) with St. Jude Medical Quartet leads (P <0.001) had at least 1 electrode located at nonapical segments linked with a PNS -PCT safety margin of more than 2 V. During the 6-month follow -up, PNS was detected in 4 patients and was eliminated with reprogramming. No significant changes in PCT were detected during follow -up. CONCLUSIONS: Quadripolar leads allowed nonapical pacing with acceptable electrical parameters in the majority of CRT recipients, although differences were found among the currently available devices.

Challenging Cases of Wide Complex Tachycardias: Use and Limits of Algorithms.

Electrocardiographic algorithms are particularly useful to differentiate, in the presence of a wide complex tachycardia, between supraventricular aberrancy and ventricular tachycardias (VT). There are numerous limitations to the sensitivity and specificity of these algorithms including the presence of accessory pathways, use of antiarrhythmic drugs, congenital heart diseases, electrolytes impairments, and artificial pacing. Once the diagnosis of VT has been reached, other algorithms can help in localizing the origin of the ventricular arrhythmia. These approaches are also limited by the anatomic structure of where the arrhythmia originates. This article illustrates the difficulties in applying common algorithms in many clinical circumstances.

Subcutaneous implantable cardioverter defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy: Results from an Italian multicenter registry.

BACKGROUND: Despite expanding indication of the subcutaneous implantable cardioverter defibrillator (S-ICD) in clinical practice, limited data exists on safety and efficacy of S-ICD in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. The aim of this multicenter study was to evaluate the safety and efficacy of S-ICD in ARVC patients. METHODS: The study population included 44 consecutive patients with definite ARVC diagnosis according to the 2010 ITF criteria (57% male, mean age 37 ±â€¯17 years [range 10-75 years]) who received an S-ICD. Eighteen (41%) patients were implanted for secondary prevention. RESULTS: At implant, all inducible patients (34/44) had conversion of ventricular fibrillation at 65 J. No early complications occurred. During a median follow-up of 12 months (7-19), 3 (6.8%) patients experienced complications requiring surgical revision. No local or systemic device-related infections were observed. Six patients (14%) received a total of 61 appropriate and successful shocks on ventricular arrhythmias. Six (14%) patients experienced 8 inappropriate shocks for oversensing of cardiac signal (4 cases) and non-cardiac signal (4 cases) with one patient requiring device explantation. No patients had the device explanted due to the need for antitachycardia pacing. CONCLUSIONS: The study shows that S-ICD provides safe and effective therapy for termination of both induced and spontaneous malignant ventricular tachyarrhythmias with high energy shocks in ARVC patients, but the risk of inappropriate shocks and complications needing surgical revision should be considered.

Peculiar Electrocardiographic Aspects of Wide QRS Complex Tachycardia: When Differential Diagnosis Is Difficult.

Wide complex tachycardia may represent a challenge for correct interpretation of standard electrocardiogram, which is crucial for proper patient management. For this reason, algorithms based on electrocardiographic criteria have been developed to guide interpretation in a step-by-step approach. Despite their greater accuracy, some cases of wide QRS complex tachycardia are a challenge. Some peculiar forms of ventricular tachycardia, and complex supraventricular substrate or particular clinical condition, may originate a challenging electrocardiographic pattern. In this article, a series of peculiar cases of wide QRS complex tachycardia is presented as paradigm of how important a comprehensive clinical approach is in these patients.