Fascicular tachycardia and parasystole of right bundle branch origin

Multifocal Ventricular Arrhythmias Originating From the His-Purkinje System: Incidence, Characteristics, and Outcome of Catheter Ablation

OBJECTIVES

This study sought to reveal the characteristics and radiofrequency catheter ablation (RFCA) outcomes of multifocal His-Purkinje system (HPS) ventricular arrhythmias (VAs).

BACKGROUND

The details of those VAs, especially the safety and efficacy of their RFCA treatment, remain unclear.

METHODS

Thirty consecutive patients who underwent RFCA of focal HPS VAs between 2010 and 2016 (unifocal = 24, multifocal = 6) were studied by measuring the electrophysiological variables within the HPS.

RESULTS

Multifocal premature ventricular contractions (n = 1) and ventricular fibrillation (VF) (n = 5) were identified in the left posterior (n = 6), anterior (n = 4), and septal fascicles (n = 1), as well as the basal left bundle branch (LBB) (n = 2) and right bundle branch (RBB) (n = 2). In 2 patients with unifocal VAs and 4 patients with multifocal VAs, preferential conduction from an origin within the proximal fascicle (n = 4) or LBB (n = 2) to ≤3 breakout sites in the distal fascicles occurred with split or fractionated Purkinje potentials and/or conduction block at the site of origin. Among the multifocal VAs, 11 fascicle VAs, 1 RBB VA, and 1 LBB VA were successfully ablated with fascicular and/or bundle branch block, and complete atrioventricular block (CAVB), respectively. In the remaining LBB VAs and RBB VAs, RFCA was abandoned to avoid CAVB. Recurrence of ablated VAs or the incidence of VF did not differ between the unifocal and multifocal HPS VAs. Freedom from any HPS VA after RFCA was significantly higher in the patients with unifocal VAs than in the patients with multifocal VAs (92% vs. 33%; p = 0.001).

CONCLUSIONS

Multifocal HPS VAs could occur and often present with preferential conduction from proximal origins to distal breakout sites within the HPS with abnormal Purkinje potentials and/or conduction properties. RFCA was effective but was limited by the risk of HPS impairment.

Idiopathic accelerated idioventricular rhythm or ventricular tachycardia originating from the right bundle branch: unusual type of ventricular arrhythmia

BACKGROUND

Accelerated idioventricular rhythm (AIVR) or ventricular tachycardia (VT) originating from the right bundle branch (RBB) is rare and published clinical data on such arrhythmia are scarce. In this study, we will describe the clinical manifestations, diagnosis, and management of a cohort of patients with this novel arrhythmia.

METHODS AND RESULTS

Eight patients (5 men; median age, 25 years) with RBB-AIVR/VT were consecutively enrolled in the study. Pharmacological testing, exercise treadmill testing, electrophysiological study, and catheter ablation were performed in the study patients, and ECG features were characterized. All RBB-AIVR/VTs were of typical left bundle-branch block morphology with atrioventricular dissociation. The arrhythmias, which demonstrated chronotropic variability, were often isorhythmic with sinus rhythm and were accelerated by physical exercise, stress, and intravenous isoprenaline infusion. The rate of RBB-AIVR/VT varied from 45 to 200 beats per minute. Two patients experienced syncope, and 3 had impaired left ventricular function. Metoprolol was proven to be the most effective drug to decelerate the arrhythmia rate and relieve symptoms. Electrophysiology study was performed in 5 patients and the earliest activation with a sharp RBB potential was localized in the mid or distal RBB area. Catheter ablation terminated the arrhythmia with subsequent RBB block morphology during sinus rhythm. During follow-up, patients' symptoms were controlled with normalization of left ventricular function either on metoprolol or by catheter ablation.

CONCLUSIONS

RBB-AIVR/VT is an unusual type of ventricular arrhythmia. It can result in significant symptoms and depressed ventricular function and can be successfully treated with catheter ablation.