Catheter Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Abstract

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is predominantly an inherited cardiomyopathy with typical histopathological characteristics of fibro-fatty infiltration mainly involving the right ventricular (RV) inflow tract, RV outflow tract, and RV apex in the majority of patients. The above pathologic evolution frequently brings patients with ARVD/C to medical attention owing to the manifestation of syncope, sudden cardiac death (SCD), ventricular arrhythmogenesis, or heart failure. To prevent future or recurrent SCD, an implantable cardiac defibrillator (ICD) is highly desirable in patients with ARVD/C who had experienced unexplained syncope, hemodynamically intolerable ventricular tachycardia (VT), ventricular fibrillation, and/or aborted SCD. Notably, the management of frequent ventricular tachyarrhythmias in ARVD/C is challenging, and the use of antiarrhythmic drugs could be unsatisfactory or limited by the unfavorable side effects. Therefore, radiofrequency catheter ablation (RFCA) has been implemented to treat the drug-refractory VT in ARVD/C for decades. However, the initial understanding of the link between fibro-fatty pathogenesis and ventricular arrhythmogenesis in ARVD/C is scarce, the efficacy and prognosis of endocardial RFCA alone were limited and disappointing. The electrophysiologists had broken through this frontier after better illustration of epicardial substrates and broadly application of epicardial approaches in ARVD/C. In recent works of literature, the application of epicardial ablation also successfully results in higher procedural success and decreases VT recurrences in patients with ARVD/C who are refractory to the endocardial approach during long-term follow-up. In this article, we review the important evolution on the delineation of arrhythmogenic substrates, ablation strategies, and ablation outcome of VT in patients with ARVD/C.

Keywords: Arrhythmogenic right ventricular dysplasia-cardiomyopathy; Catheter ablation; Percutaneous epicardial mapping; Ventricular tachycardia.

Figure 1. Example of differences in the bipolar voltage map created using the 1-mm electrode catheter and 3.5-mm electrode catheter in the patient with ARVD/C. During substrate mapping and activation mapping, the 1-mm electrode catheter (upper panel) identified the potential channels (white arrows and white arrowheads) in the epicardial RV inferior free wall and inferior tricuspid annulus (left and middle panel). The local electrograms of 1-mm electrode catheter showed delayed fractionated potential at the distal part of the conducting isthmus during sinus rhythm (right penal). On the other hand, the 3.5-mm electrode catheter (lower panel) in the same area could not identify the conduction gap within the epicardial scar in the same area (left and middle panel). The local electrograms of 3.5-mm electrode catheter only identified far-field potential at the same area during sinus rhythm (right penal).

ARVD/C = arrhythmogenic right ventricular dysplasia/cardiomyopathy; ECG = electrocardiography; RV = right ventricle.

Figure 2. 3D electro-anatomic characteristics in the patients with ARVD/C. Example of substrate mapping in a patient with definite ARVD/C. The distribution of electroanatomic bipolar and unipolar scar typically extends from the tricuspid annulus and RVOT toward the RV free wall (A–C) and RV apex. The septum was scar-sparing. The electroanatomic bipolar epicardial scar area was correlated to the endocardial unipolar low-voltage area at a cut-off threshold of 5.5 mV (D).

3D = 3-dimensional; ARVD/C = arrhythmogenic right ventricular dysplasia/cardiomyopathy; AP = anteroposterior; PA = posteroanterior; RV = right ventricle; RVOT = right ventricular outflow tract; TV = tricuspid valve.

Figure 3. Elimination of epicardial arrhythmogenic potentials by endocardial catheter ablation. An example of elimination of epicardial LPs by endocardial ablation in a patient with ARVD/C and sustained VT. 2 clinical VTs with difference axis were induced during the electrophysiological study (A). The ablation catheter and multielectrode catheter nearby the corresponding isthmus showed mid-diastolic potentials (yellow stars) during VT and delayed potential after VT terminated into sinus rhythm (B). Catheter ablation from the endocardium eliminated the LPs of the corresponding epicardial area successfully. Notably, the epicardial LPs were disappeared before the elimination of endocardial LP (yellow stars). Additionally, the programmed extra-stimuli revealed non-inducible after ablation. The 3D electro-anatomic mapping of epicardial showed the conducing isthmus surrounded by epicardial scar. The shadow of the multielectrode catheter represented the position during VT mapping and endocardial ablation (D, E).

3D = three-dimensional; ARVD/C = arrhythmogenic right ventricular dysplasia/cardiomyopathy; EP = electrophysiological; LP = late potential; VT = ventricular tachycardia.