Catheter ablation of idiopathic premature ventricular contractions and ventricular tachycardias originating from right ventricular septum

Abstract

Background: Idiopathic premature ventricular contractions (PVCs) and ventricular tachycardias (IVTs) originating from the subtricuspid septum and near the His bundle have been reported. However, little is known about the prevalence, distribution, electrocardiographic characteristics and the efficacy of radiofrequency catheter ablation (RFCA) for the ventricular arrhythmias arising from the right ventricular (RV) septum. This study aimed to investigate electrocardiographic characteristics and effects of RFCA for patients with symptomatic PVCs/IVTs, originating from the different portions of the RV septum.

Methodology/principal findings: Characteristics of body surface electrocardiogram and electrophysiologic recordings were analyzed in 29 patients with symptomatic PVCs/IVTs originating from the RV septum. Among 581 patients with PVCs/IVTs, the incidence of ventricular arrhythmias originating from the RV septum was 5%. Twenty (69%) had PVCs/IVTs from the septal portion of the tricuspid valvular RV region (3 from superoseptum, 15 from midseptum, 2 from inferoseptum), and 9 (31%) from the septal portion of the basal RV (1 from superoseptum, 4 from midseptum, 4 from inferoseptum). There were different characteristics of ECG of PVCs/VT originating from the different portions of the RV septum. Twenty-seven of 29 patients with PVCs/IVTs arising from the RV septum were successfully ablated (93.1% acute success).

Conclusions/significance: ECG characteristics of PVCs/VTs originating from the different portions of the RV septum are different, and can help regionalize the origin of these arrhythmias. The septal portion of the tricuspid valvular RV region was the preferential site of origin. RFCA was effective and safe for the PVCs/IVTs arising from the RV septum.

Figure 1. Schematic left lateral (A) and right anterior oblique (B) view of the right ventricular septum divided into nine regions and indicating the distribution of the origin of idiopathic ventricular arrhythmias, represented by red dots (successful ablation sites) and green dots (unsuccessful ablation sites).

TV Sup: the superoseptal portion of the tricuspid valvular right ventricular region; TV Mid: the midseptal portion of the tricuspid valvular right ventricular region; TV Inf: the inferoseptal portion of the tricuspid valvular right ventricular region; Basal Sup: the superoseptal portion of the basal right ventricular region; Basal Mid: the midseptal portion of the basal right ventricular region; Basal Inf: the inferoseptal portion of the basal right ventricular region; Apical Sup: the superoseptal portion of the apical right ventricular region; Apical Mid: the midseptal portion of the apical right ventricular region; Apical Inf: the inferoseptal portion of the apical right ventricular region; His: largest His-bundle potential (yellow dot); CS: coronary sinus (blue dot).

Figure 2. Example of a unsuccessful ablation of a premature ventricular contraction (PVC) originating from the superoseptal portion of the tricuspid valvular right ventricular region.

No attempt at ablation was undertaken because the origin of the PVC was found to be near the His-bundle. (A) The surface ECG characteristic. (B) The local ventricular activation time recorded at the site that preceded the onset of the QRS complex was 41 ms. A sharp His electrogram at the site was recorded in sinus rhythm. (C) Pace map at the site. (D) The fluoroscopic position of the ablation catheter and the His-bundle catheter sites. The site of the origin of the PVC was just less than 1 cm superior to the His-bundle catheter. ABL, ablation catheter; RAO, right anterior oblique projection; LAO, left anterior oblique projection.

Figure 3. Representative 12-lead electrocardiograms of premature ventricular contractions originating from the right ventricular septum.

A: the superoseptal portion of the tricuspid valvular right ventricular region; B: the midseptal portion of the tricuspid valvular right ventricular region; C: the inferoseptal portion of the tricuspid valvular right ventricular region; D: the superoseptal portion of the basal right ventricular region; E: the midseptal portion of the basal right ventricular region; F: the inferoseptal portion of the basal right ventricular region; G: Schematic right anterior oblique (RAO) view of the right ventricular septum displaying the sites of origin of the PVC/IVTs, represented by the red dots. His: largest His-bundle potential (yellow dot); CS: coronary sinus (blue dot).

Figure 4. Example of a successful ablation of a premature ventricular contraction (PVC) originating from the inferoseptal portion of the tricuspid valvular right ventricular region.

(A) The surface ECG characteristic. (B) The local ventricular activation time recorded at the successful ablation site that preceded the onset of the QRS complex was 33 ms. (C) Pace map at the ablation site. (D) The fluoroscopic position of the ablation catheter site. (E) Green dot indicates site of RF application under the guide of Carto 3. ABL, ablation catheter; RAO, right anterior oblique projection; LAO, left anterior oblique projection; Septal, right ventricular septum; FW, right ventricular free wall; TA, tricuspid annulus.

Figure 5. Example of a successful ablation of a premature ventricular contraction (PVC) originating from the midseptal portion of the tricuspid valvular right ventricular region.

(A) The surface ECG characteristic. (B) The local ventricular activation time recorded at the successful ablation site that preceded the onset of the QRS complex was 31 ms. (C) Pace map at the ablation site. (D) The fluoroscopic position of the ablation catheter and the His-bundle catheter sites. (E) Red dot indicates site of RF application under the guide of Ensite NavX. ABL, ablation catheter; RAO, right anterior oblique projection; LAO, left anterior oblique projection.

Figure 6. Example of a successful ablation of a premature ventricular contraction (PVC) originating from the midseptal portion of the basal right ventricular region.

(A) The surface ECG characteristic. (B) The local ventricular activation time recorded at the successful ablation site that preceded the onset of the QRS complex was 20 ms. (C) Pace map at the ablation site. (D) The fluoroscopic position of the ablation catheter site. (E) Termination of PVCs within 3 seconds during RF application at the site. ABL, ablation catheter; RAO, right anterior oblique projection; LAO, left anterior oblique projection.

Figure 7. Example of a successful ablation of a premature ventricular contraction (PVC) originating from the inferoseptal portion of the basal right ventricular region.

(A) The surface ECG characteristic. (B) The local ventricular activation time recorded at the successful ablation site that preceded the onset of the QRS complex was 32 ms. (C) Pace map at the ablation site. (D) The fluoroscopic position of the ablation catheter site. ABL, ablation catheter; RAO, right anterior oblique projection; LAO, left anterior oblique projection.

Figure 8. Differences in (A) QS pattern in lead V1 between PVCs/IVTs arising from the RV superoseptum and mid-inferoseptum and (B) precordial R-wave transition occurring by lead V4 between PVCs/VTs arising from the tricuspid valvular and basal right ventricular septum.

Figure 9. Differences in (A) Monophasic R pattern in three inferior leads between PVCs/IVTs arising from the right ventricular outflow tract (RVOT) and not arising from the right ventricular outflow tract (NRVOT) and (B) QS pattern in lead V1 between PVCs/VTs arising from the RV septum (Septal) and free wall (FW).

Figure 10. Distribution of QRS duration in patients with idiopathic PVC/VTs arising from the right ventricular septum (Septal) and free wall (FW).

The QRS duration of ≦143.5 suggested the right ventricular septum origin with high sensitivity and specificity.

Figure 11. Pace mapping from the different regions of the right ventricular septum.

A: Schematic right anterior oblique (RAO) view of the right ventricular septum displaying the different pacing sites represented by the red dots; B: The characteristics of the QRS morphology during pacing at the different regions of the right ventricular septum. 1, the superoseptal portion of the tricuspid valvular right ventricular region; 2, the midseptal portion of the tricuspid valvular right ventricular region; 3, the inferoseptal portion of the tricuspid valvular right ventricular region; 4: the superoseptal portion of the basal right ventricular region; 5: the midseptal portion of the basal right ventricular region; 6: the inferoseptal portion of the basal right ventricular region; 7, the midseptal portion of the apical right ventricular region; 8, the inferoseptal portion of the apical right ventricular region.