Venice Chart International Consensus document on ventricular tachycardia/ventricular fibrillation ablation

[Incessant or recurrent ventricular tachycardia. Indications for emergency ablation]

Incessant ventricular tachycardia and "electrical storms" are emergencies, requiring urgent action in a close cooperation between critical care physicians and cardiologists. The leading cause of such events is advanced cardiac disease. Besides the patient's history, an ECG and, if applicable, an implantable cardioverter-defibrillator (ICD) interrogation is required for a reliable diagnosis. Further diagnostics include laboratory parameters, an echocardiogram, and possibly a coronary angiography. The medical therapy, consisting of amiodarone and β-blockers, should immediately be initiated after diagnosis. In the case of failed drug therapy, urgent catheter ablation is indicated. This is a complex procedure, in which the clinical tachycardia or the electrical substrate is modified by using an irrigated catheter. The acute success rate of this life-saving procedure is high. However, there might also be complications due to the required extensive procedures.

Three-dimensional mapping of cardiac arrhythmias - string of pearls -

The evolution of 3-dimensional (D) mapping systems has contributed to improved procedures for ablation of complex tachyarrhythmia in terms of providing detailed anatomical information along with the ability to integrate with pre-acquired computed tomography/magnetic resonance imaging/intracardiac echocardiography images, reducing the radiation exposure, and producing activation and substrate maps. 3-D mapping systems are categorized as magnetic based vs. impedance based according to the catheter location technology, and are also classified as contact based vs. non-contact based according to the data collection technology. Contact-based mapping systems are used widely, in which a series of electrograms is taken sequentially in contact with the heart, thus requiring a relatively stable and sustained arrhythmia to create an activation map. Non-contact mapping systems, however, allow a beat-to-beat analysis of the activation even in non-sustained, polymorphic, or hemodynamically intolerant tachycardia. In this article, the clinical utility of 3-D mapping systems is discussed based on the literature and on experience, with particular emphasis on the non-contact mapping system.

Role of catheter ablation of ventricular tachycardia associated with structural heart disease

In patients with structural heart disease, ventricular tachycardia (VT) worsens the clinical condition and may severely affect the short- and long-term prognosis. Several therapeutic options can be considered for the management of this arrhythmia. Among others, catheter ablation, a closed-chest therapy, can prevent arrhythmia recurrences by abolishing the arrhythmogenic substrate. Over the last two decades, different techniques have been developed for an effective approach to both tolerated and untolerated VTs. The clinical outcome of patients undergoing ablation has been evaluated in multiple studies. This editorial gives an overview of the role, methodology, clinical outcome and innovative approaches in catheter ablation of VT.

Efficacy and safety of ventricular tachycardia ablation with mechanical circulatory support compared with substrate-based ablation techniques

AIMS

Catheter ablation of ventricular tachycardia (VT) can be limited by haemodynamic instability. In these cases, substrate-based ablation is typically performed. An alternative is to perform activation and entrainment mapping during VT supported by a percutaneous left ventricular assist device (pVAD). We sought to compare the complication and success rates of pVAD-assisted VT ablation with scar-based techniques.

METHODS AND RESULTS

Thirteen consecutive patients with haemodynamically unstable VT underwent pVAD-assisted ablation (pVAD group) and were retrospectively compared with 18-matched patients undergoing a substrate-based VT ablation (non-pVAD group). There was no significant difference in age or ejection fraction between the groups although pVAD patients tended to have more shocks in the preceding months. Procedure times were longer for the pVAD group. The number of monomorphic VTs induced was greater in the pVAD group (3.2 vs. 1.6, P= 0.04); however, after ablation, there was no difference in inducibility between the pVAD and non-pVAD group (10 of 13 vs. 12 of 18; 77 vs. 67%, P = 0.69). There was no difference in acute complications including stroke or death. At 9 ± 3 months, 1-year freedom from implantable cardioverter-defibrillator (ICD) shocks/therapies for sustained VT were similar (P= 0.96). In multivariable analysis, the absence of atrial fibrillation (hazard ratio=0.15, P= 0.04) was associated with a lower incidence of ICD shocks.

CONCLUSIONS

In high-risk patients, pVAD-assisted VT ablation guided by activation and entrainment mapping is a feasible alternative to substrate mapping and allows outcomes comparable to substrate mapping.

Use of ventricular synchronized triggered atrial pacing to facilitate hemodynamic support during mapping and catheter ablation of ventricular vachycardia

Use of VSTAP to Facilitate Hemodynamic Support. The ablation of hemodynamically unstable ventricular tachycardia (VT) is challenging and frequently requires alternative mapping techniques or the use of percutaneous mechanical support devices. Loss of atrioventricular synchrony contributes to hemodynamic compromise during VT. In order to facilitate successful mapping and ablation of unstable VT, we employed ventricular synchronized triggered atrial pacing (VSTAP) at 50% of the RR interval. In this case, triggered atrial pacing permitted activation mapping and, subsequently, successful ablation of the patient's unstable VT. Thus, VSTAP is a readily available and noninvasive technique that may provide adequate hemodynamic support during catheter ablation of unstable VT.

Incidence, risk factors, and consequences of new-onset atrial fibrillation following epicardial ablation for ventricular tachycardia

INTRODUCTION

We sought to determine the incidence, predictors, and consequences of new-onset atrial fibrillation (AF) following epicardial ventricular tachycardia (VT) ablation.

METHODS AND RESULTS

A total of 41 patients with no prior history of AF underwent epicardial VT ablation via a percutaneous subxiphoid approach. All patients were monitored continuously for 3 days following ablation and then via implantable cardiac defibrillator (ICD) or Holter monitoring. Mean age was 70.0 ± 11.3 years and mean ejection fraction was 30.3 ± 16.6%. In seven (17%) patients, the right ventricle (RV) was punctured during access with subsequent needle withdrawal without requiring surgical repair. Thirty patients (73%) were treated with amiodarone following ablation. Post-ablation, eight (19.5%) patients had documented new-onset AF within 7 days. All AF patients had clinical symptoms of pericarditis. One patient with AF was maintained on amiodarone post-procedure. Complications of AF included three patients who received inappropriate ICD shocks and one patient who developed a large, left atrial appendage clot. Acutely, all patients responded to short-term medical therapy or electrical cardioversion. At 18.0 ± 9.0 months of follow-up, no patient had recurrence of AF, and all were off antiarrhythmic drugs. One patient had typical atrial flutter requiring catheter ablation. Risk factors for AF included lack of amiodarone immediately after ablation (12.5 vs. 87.9%, P < 0.001), RV puncture (50.0 vs. 9.1%, P = 0.02), and epicardial ablation time >10 min (62.5 vs. 3.0%, P < 0.001).

CONCLUSIONS

Atrial fibrillation after epicardial ablation is common and can lead to ICD shocks and atrial thrombus formation. Short-term antiarrhythmic drug therapy and ICD reprogramming should be considered after epicardial VT ablation.

Direct visualization of epicardial structures and ablation utilizing a visually guided laser balloon catheter: preliminary findings

BACKGROUND

Intrapericardial mapping and ablation can be utilized to target epicardial arrhythmic circuits. Current epicardial ablation strategies are associated with risk of damage to adjacent structures, including the coronary vasculature and phrenic nerves.

OBJECTIVES

The purpose of this study was to evaluate the feasibility of an investigational, visually guided laser balloon catheter for manipulation within the pericardial space, visualization of epicardial structures, and delivery of laser ablation lesions to the ventricular myocardium.

METHODS

Pericardial access was obtained in 4 anesthetized swine by subxyphoid puncture. The laser balloon catheter was introduced into the pericardial space via a deflectable sheath, and was manipulated to predefined regions in all animals. Visually guided laser ablation was performed on the ventricular myocardium, with post mortem examination of lesion size and depth.

RESULTS

The laser ablation catheter could be manipulated to all targeted regions in all animals. Associated structures, including epicardial coronary arteries and veins as well as an endocardial catheter in the left atrial appendage, were easily visualized. A total of 9 laser energy applications at varying power/time settings were performed. Ablation utilizing moderate (7-8.5 W) power produced relatively uniform lesions (diameter 5-12 mm, depth 6-9 mm), while high (14 W) power produced a visible "steam pop" with a large, hemorrhagic lesion (22 × 11 × 11 mm).

CONCLUSIONS

The investigational laser balloon catheter can be manipulated within the epicardial space, allowing for direct visualization of surrounding structures during ablation. Titration of laser power can be utilized to create moderate-sized ablation lesions while avoiding steam pops.

Meta-analysis of catheter ablation as an adjunct to medical therapy for treatment of ventricular tachycardia in patients with structural heart disease

BACKGROUND

Most studies of catheter ablation for the treatment of ventricular tachycardia (VT) are relatively small observational trials.

OBJECTIVE

The purpose of this study was to define the relative risk of VT recurrence in patients undergoing catheter ablation as an adjunct to medical therapy versus medical therapy alone in a pooled analysis of controlled studies.

METHODS

Randomized and nonrandomized controlled trials of patients who underwent adjunctive catheter ablation of VT versus medical therapy alone were sought. MEDLINE, EMBASE, the Cochrane central register of controlled trials (CENTRAL), and Web of Science were searched from 1965 to July 2010. Supplemental searches included Internet resources, reference lists, and reports of arrhythmia experts. Three authors independently reviewed and extracted the data regarding baseline characteristics, ablation methodology, medical therapy, complications, VT recurrences, mortality, and study quality.

RESULTS

Five studies were included totaling 457 participants with structural heart disease. Adjunctive catheter ablation was performed in 58% of participants, whereas 42% received medical therapy alone for VT. Complications of catheter ablation included death (1%), stroke (1%), cardiac perforation (1%), and complete heart block (1.6%). Using a random-effects model, a statistically significant 35% reduction in the number of patients with VT recurrence was noted with adjunctive catheter ablation (P<.001). There was no statistically significant difference in mortality.

CONCLUSIONS

Catheter ablation as an adjunct to medical therapy reduces VT recurrences in patients with structural heart disease and has no impact on mortality.

The origin of epicardial ventricular tachycardia revealed by entrainment from a permanent epicardial left ventricular pacing lead

Entrainment From Left Ventricular Pacing Lead. Recognizing ventricular tachycardias (VTs) that require epicardial ablation is desirable, but challenging when prior surgery prevents percutaneous epicardial mapping. This patient had cardiomyopathy, prior cardiac surgery, and VT that failed endocardial ablation. Observing that the Bi-V implantable cardioverter defibrillator (ICD), left ventricular (LV) lead was epicardial to the area of infarct scar, it was used to pace during VT. Entrainment with concealed fusion with long stimulus to QRS interval, consistent with an epicardial VT circuit, was observed. Surgical cryoablation targeting the area around the LV lead eliminated VT. Thus pacing maneuvers from permanent epicardial leads can occasionally help identify an epicardial VT origin.