Atypical variants of right ventricular outflow arrhythmias

Re-entrant ventricular tachycardia as a complication of ablation of idiopathic ventricular premature beats from the right outflow tract: a case report

Background

We report an unusual case of non-sustained ventricular tachycardia (NSVT) from the epicardial part of the right ventricular outflow tract (RVOT).

Case summary

A 37-year-old woman who underwent in 2006 an ablation for idiopathic ventricular premature beats (VPBs) from the RVOT presented with pre-syncopal NSVT in 2016. A cardiac workup showed no coronary disease, normal biventricular function, and no enhancement on cardiac magnetic resonance imaging. A metabolic positron emission tomography scan excluded inflammation. Biopsies revealed normal desmosomal proteins. An endocardial mapping revealed an area of low voltage potential (<0.5 mV) at the antero-septal aspect of the RVOT corresponding to the initial site of ablation from 2006. Activation mapping revealed poor prematurity and pace-mapping showed unsatisfactory morphologies in the RVOT, the left ventricle outflow tract and the right coronary cusp. An epicardial map revealed a low voltage area at the antero-septal aspect of the RVOT with fragmented potentials opposite to the endocardial scar. Pace-mapping demonstrated perfect match. An NSVT was induced and local electrocardiogram showed mid-diastolic potentials. Ablation was applied epicardially and endocardially without any complication. The patient was arrhythmia free at 4-year follow-up.

Discussion

Cardiac workup allowed to exclude specific conditions such as arrhythmogenic cardiomyopathy, tetralogy of Fallot, sarcoidosis, or myocarditis as a cause for NSVT from the RVOT. The epi and endocardial map showed residual scar subsequent to the first ablation which served as substrate for the re-entrant NSVT. This is the first case which describes NSVT from the epicardial RVOT as a complication from a previous endocardial ablation for idiopathic VPB.

Outflow tract ventricular arrhythmias : Electrocardiographic features in relation to mapping and ablation

Ventricular arrhythmia arising from the outflow tracts can manifest itself as frequent premature ventricular complexes (PVCs), salvos of ventricular tachycardia (VT), and/or sustained VT. It is amenable to management with medication and catheter ablation without need for an intracardiac defibrillator. The electrocardiogram (ECG) is a crucial tool in the management of these patients as it is can help localize the site of origin, thereby helping guide the electrophysiologist. An appreciation of the unique anatomy of the outflow tracts as well as their relationships with the surrounding structures is essential in interpreting the ECG. In this review, we examine the ECG features of the various outflow tract arrhythmia morphologies with a focus on anatomy and provide an approach to the ablation of these abnormal rhythms.

Disappearance of Idiopathic Outflow Tract Premature Ventricular Contractions After Catheter Ablation of Overt Accessory Pathways

BACKGROUND

Multiple mechanisms have been proposed for idiopathic premature ventricular contractions (PVCs) originating from the outflow tracts (OTs). Recent observations such as the coexistence of these arrhythmias with atrioventricular nodal reentrant tachycardias and the association between discrete prepotentials and successful ablation sites of ventricular arrhythmias (VAs) from the OTs suggest a common link.

OBJECTIVE

In this case series we draw attention to a unique association between accessory pathways (APs) and idiopathic PVCs from the OTs, disappearing after AP ablation.

METHODS

We identified 6 cases in collaboration with several international electrophysiology centers, which presented with pre-excitation in association with OT, and in 1 case inflow tract (IT), PVCs on 12-lead surface ECG.

RESULTS

Six cases displayed pre-excitation and PVCs, in 5 cases originating from the right ventricular outflow tract (RVOT) and in 1 case from the right ventricular inflow tract (RVIT). In all patients, PVCs were monomorphic and had fixed coupling intervals, in 3 cases presenting in bigeminy. Catheter ablation of the AP led to the simultaneous disappearance of PVCs in 5 of 6 cases. The sites of ablation were remote from the OTs in all these cases. In most cases, the occurrence of OT PVCs was closely associated with the presence of pre-excitation.

CONCLUSION

The coexistence of pre-excitation and PVCs from the OTs and the fact that in 5 of 6 cases PVCs disappeared after AP ablation suggests a common mechanism for arrhythmia genesis.