Mechanisms of ventricular tachycardias with a 1:1 His-V relation in patients with heart disease.

BACKGROUND

Ventricular tachycardia (VT) with a 1:1 V-His relation can be seen in bundle branch reentry or with passive retrograde activation from scar-related VT or reentry using left ventricular Purkinje fascicles.

OBJECTIVE

This study aimed to review the frequency with which 1:1 V-His relation occurs and to identify differentiating characteristics of these arrhythmias, including new measures obtained during right ventricular (RV) pacing based on orthodromic His-proximal right bundle potential (HisRB) capture and the stimulus to HisRB (S-HisRB) interval approximating RV electrogram to His interval (Egm-HisRBVT).

METHODS

This was a retrospective review of induced VTs that had a HisRB potential recorded while pacing from the distal right ventricle.

RESULTS

From 147 patients, 158 VTs were analyzed. A 1:1 V to HisRB was observed in 86 VTs (54%): 18 bundle branch reentrant VTs (BBR-VTs), 8 LV fascicular/Purkinje-related reentrant VTs (FPVTs), and 60 scar-related reentrant VTs (SRR-VTs). The HisRB-QRSVT was >135 ms, falling within the QRS in 87% of SRR-VTs, and 30-135 ms in all BBR-VTs (P < .001). With RV pacing, the HisRB remained 1:1 in 100% of BBR-VTs and 23 (69.7%) of 33 SRR-VTs. An S-HisRB of >135 ms combined with S-HisRB - Egm-HisRBVT difference <30 ms was specific for BBR-VT. In FPVTs, the HisRB-QRS timing was more variable, and RV pacing was helpful in distinguishing these from BBR-VTs.

CONCLUSION

Retrograde HisRB activation is common in all forms of VT. HisRB timing and new features based on consideration of orthodromic HisRB activation during RV pacing can help distinguish BBR-VT, SRR-VT, and FPVT.