Catheter-based cryoablation of postinfarction and idiopathic ventricular tachycardia: initial experience in a selected population

Preclinical Study of Pulsed Field Ablation of Difficult Ventricular Targets: Intracavitary Mobile Structures, Interventricular Septum, and Left Ventricular Free Wall

BACKGROUND

Endocardial catheter-based pulsed field ablation (PFA) of the ventricular myocardium is promising. However, little is known about PFA's ability to target intracavitary structures, epicardium, and ways to achieve transmural lesions across thick ventricular tissue.

METHODS

A lattice-tip catheter was used to deliver biphasic monopolar PFA to swine ventricles under general anesthesia, with electroanatomical mapping, fluoroscopy and intracardiac echocardiography guidance. We conducted experiments to assess the feasibility and safety of repetitive monopolar PFA applications to ablate (1) intracavitary papillary muscles and moderator bands, (2) epicardial targets, and (3) bipolar PFA for midmyocardial targets in the interventricular septum and left ventricular free wall.

RESULTS

(1) Papillary muscles (n=13) were successfully ablated and then evaluated at 2, 7, and 21 days. Nine lesions with stable contact measured 18.3±2.4 mm long, 15.3±1.5 mm wide, and 5.8±1.0 mm deep at 2 days. Chronic lesions demonstrated preserved chordae without mitral regurgitation. Two targeted moderator bands were transmurally ablated without structural disruption. (2) Transatrial saline/carbon dioxide assisted epicardial access was obtained successfully and epicardial monopolar lesions had a mean length, width, and depth of 30.4±4.2, 23.5±4.1, and 9.1±1.9 mm, respectively. (3) Bipolar PFA lesions were delivered across the septum (n=11) and the left ventricular free wall (n=7). Twelve completed bipolar lesions had a mean length, width, and depth of 29.6±5.5, 21.0±7.3, and 14.3±4.7 mm, respectively. Chronically, these lesions demonstrated uniform fibrotic changes without tissue disruption. Bipolar lesions were significantly deeper than the monopolar epicardial lesions.

CONCLUSIONS

This in vivo evaluation demonstrates that PFA can successfully ablate intracavitary structures and create deep epicardial lesions and transmural left ventricular lesions.

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.

Ablation of idiopathic ventricular tachycardia

Idiopathic ventricular arrhythmias occur in patients without structural heart disease. They can arise from a variety of specific areas within both ventricles and in the supravalvular regions of the great arteries. Two main groups need to be differentiated: arrhythmias from the outflow tract (OT) region and idiopathic left ventricular, so-called fascicular, tachycardias (ILVTs). OT tachycardia typically originates in the right ventricular OT, but may also occur in the left ventricular OT, particularly in the sinuses of Valsalva or the anterior epicardium or the great cardiac vein. Activation mapping or pace mapping for the OT regions and mapping of diastolic potentials in ILVTs are the mapping techniques that are typically used. The ablation of idiopathic ventricular arrhythmias is highly successful, associated with only rare complications. Newly recognized entities of idiopathic ventricular tachycardias are those originating in the papillary muscles and in the atrioventricular annular regions.