Premature ventricular contractions originating from the left ventricular septum: results of radiofrequency catheter ablation in twenty patients

Abstract

Background: RFCA has been established as an effective and curative therapy for severely symptomatic PVC from the outflow tract in structurally normal hearts. However, it is unknown whether PVCs originating from the left ventricular septum, are effectively eliminated by RFCA. This study aimed to investigate electrophysiologic characteristics and effects of radiofrequency catheter ablation (RFCA) for patients with symptomatic premature ventricular contraction (PVC) originating from the left ventricular septum without including fascicular PVCs.

Methods: Characteristics of body surface electrocardiogram (ECG) and electrophysiologic recordings endocardiogram in a successful RFCA target were analyzed in 20 patients with symptomatic PVCs originating from the left ventricular septum. RFCA was performed using pace mapping and activation mapping.

Results: The QRS morphology of PVCs originating from the left ventricular septum is similar to that seen in fascicular tachycardia. Most of the PVCs originated from the left septum appears in the form of ventricular parasystole. The incidence of ventricular parasystole was 70%. Sustained ventricular tachycardia was not inducible by electrical stimulation and isoproterenol infusion in all 20 patients, ablation at the site recording the earliest Purkinje potential was not effective in all 20 patients, and Purkinje potentials were not identified at successful sites during point mapping. Sixteen patients were successful with RFCA using pace mapping and activation mapping, 3 failed, and 1 recurrent.

Conclusion: Although the ECG characteristics of the PVCs arising from the left ventricular septum are similar to that seen in fascicular tachycardia, the electrophysiologic characteristics are different between the two types of PVCs. The distinguishing characteristic of the PVCs is that Purkinje potentials were not present at the site of successful ablation, suggesting a myocardial as opposed to fascicular substrate. RFCA is an effective curative therapy for symptomatic PVCs originating from the left ventricular septum (not from the left anterior and posterior fascicle).

Figure 1

Endocardial recordings of successful ablation target site originating from left anterosuperior septum. The left panel shows that the local ventricular activation time recorded at the ablation site that preceded the onset of the QRS complex was 33 ms and Purkinje potentials were not present at the site of successful ablation. The middle panel shows that pace map at the ablation site provides an identical (12/12) match with the clinical PVC morphology. The right panel shows double potential in front of PVC or VT during ablation ABL, ablation catheter.

Figure 2

Termination of the PVCs originating from left anterosuperior septum during RF application at the site. The ventricular tachycardia appeared at the beginning of ablation. The middle panel shows the fluoroscopic position of the ablation site. RAO, right anterior oblique projection; LAO, left anterior oblique projection.

Figure 3

The middle panel show endocardiogram of successful ablation target site originating from left posteroinferior septum. The left panels show ECG during ventricular pacing. The right panels show that the local ventricular activation time recorded at the successful ablation target site that preceded the onset of the QRS complex was 38 ms.

Figure 4

Representative 12-lead ECG characteristics of ventricular arrhythmia originating from left anterosuperior septum.

Figure 5

The representative 12-lead ECG characteristics of ventricular arrhythmia originating from left posteroinferior septum.