Where is the exact origin of narrow premature ventricular contractions manifesting qR in inferior wall leads?

Abstract

Background: In recent years, radiofrequency catheter ablation(RFCA) has been established as an effective therapy for idiopathic premature ventricular contractions (PVCs), however, its effect on the narrow PVCs (QRS duration < 130 msec) with qR pattern in inferior leads, may not been fully concluded.

Methods: Characteristics of 12-lead electrocardiogram (ECG) and electrophysiologic recordings were analyzed in 40 patients with symptomatic PVCs manifesting narrow QRS complex with qR pattern in inferior leads. The procedure of RFCA was performed based on pace mapping and activation mapping.

Results: Among the 40 patients with narrow PVCs, complete elimination of PVCs was achieved by RFCA in 35 patients during a median follow-up period of 23 months. Successful ablation was achieved on 19 patients at the sites where earliest Purkinje potentials were recorded in left ventricular anterosuperior septum, thus PVCs arising from left anterior fascicle (LAF) were confirmed, for these PVCs, the QRS morphology were right bundle branch and left posterior fascicle block (RBBB + LPFB) with rightward axis, the average QRS duration 116.07 ± 7.96 ms, R or rsR'in lead V1,with transition zone ahead of lead V1 in precordial leads. Another 16 successful RFCA were achieved by energy delivery at interleaflet triangle(ILT) between right coronary cusp(RCC) and left coronary cusp(LCC) where no Purkinje potentials were recorded, for narrow PVCs arising from the L-RCC ILT, the QRS morphology were similar to the PVCs arising from LAF but much narrower in QRS duration (100.44 ± 3.49 vs. 116.07 ± 7.96 ms, p < 0.05), they were also R or Rs in lead V1 with the transition zone ahead of lead V1. For 5 symptomatic narrow PVCs failed to the procedure of RFCA, their electrocardiographic characteristics showed that the narrowest QRS duration (91.80 ± 6.94 vs. 100.44 ± 3.49, 116.07 ± 7.96 ms, p < 0.05), rs or rS (r/s or r/S≦1) morphology in lead V1 with the precordial transition zone behind lead V3.

Conclusions: Most of idiopathic PVCs of narrow QRS duration (<130 msec) with qR pattern in inferior leads can be cured by the procedure of RFCA. On the basis of our study, we proposed that for narrow PVCs presenting qR pattern in inferior leads, when the ablation procedure failed at proximity of LAF within left anterosuperior septum, mapping and ablation in L-RCC ILT can be tried. The present findings can be helpful for planning catheter ablation for narrow PVCs manifesting qR in inferior leads.

Keywords: L-RCC ILT; Left anterior fascicle; Premature ventricular contractions; Radiofrequency catheter ablation.

Fig. 1

Mapping and ablation of PVCs from L-RCC LIT. a. 12-lead electrocardiogram of PVCs; b. RF energy had been applied on the site with earliest Purkinje potential in left ventricular anterosuperior septum, but the PVCs was not ablated. During PVCs, the earliest ventricular activation preceding the QRS onset by 25 ms was found in L-RCC interleaflet triangle and no Purkinje potential was recorded at this site. c1~c2 and d1~d2 The target site was confirmed by both angiography and three-dimension electroanatomical system. e. The PVCs diappeared within 10s during discharging on target site and the radiofrequency delivery was continued for 60 to 180 s. The patient has been followed up for 2.4 years without recurrence of PVCs. Annotation: PP=Purkinje potential, ABL=Ablation, RAO=Right anterior oblique position, LAO=Left anterior oblique position, RCC= Right coronary cusp, LCC=Left coronary cusp, NCC=noncoronary cusp, ILT=Interleaflet triangles, RFon=Radiofrequency on

Fig. 2

Mapping and ablation of PVCs from LAF in left anterosuperior septum. a.12-lead electrocardiogram of PVCs; b. The Purkinje potential mapped within left ventricular anterosuperior septum was 33 ms earlier the QRS onset in sinus rhythm and 39 ms earlier than the QRS onset in PVCs; c. Pacing the target sites of earliest Purkinje potential led to a perfect match, pacing reproduced QRS morphology was similar to the clinical PVCs in 11 leads; d1~d4 and e1~e2 The target site was comfirmed by X-ray image and three-dimension electroanatomical system. RF on target site led to successful ablation, no recurrence of PVCs in the follow-up of 1.4 years. Annotation: e1-e2, the red spots represented target site; the light green spots represented the Purkinje potentials

Fig. 3

Mapping and ablation of PVCs from Failure group. a. 12-lead electrocardiogram of PVCs; b. The earliest Purkinje potential preceded the QRS onset by 22 ms in sinus rhythm and preceded the QRS onset by 24 ms in PVCs, RF on the site of earliest Purkinje potential did not terminate the PVCs; c. Pacing the sites mapped with earliest ventricular activation led to a poor match, pacing reproduced QRS morphology was similar to the clinical PVCs in just 9 leads of 12 leads, RF on the site of earliest ventricular activation did not terminate the PVCs

Fig. 4

Representative 12-lead electrocardiogram of each group. a The 12-lead electrocardiogram PVCs originating from L-RCC ILT; b The 12-lead electrocardiogram of PVCs originating from LAF; c. The 12-lead electrocardiogram of ablation failure group