The effects of bundle branch block on experimental A-V reentrant tachycardia (PSVT) were studied in 17 dogs using an anomalous pathway simulatory (APS). The APS was a programmable digital electronic circuit with ability for ventricular sensing, retrograde conduction with programmable conduction time, and atrial stimulation. Close bipolar electrodes were positioned at seven contiguous atrial and ventricular sites (Vl) along the A-V ring, these being; anterior, lateral, and posterior right (AR, LR, PR), septal (S), and posterior, lateral and anterior left (PL, LL, AL). Right (R) (seven dogs) and left (L) (10 dogs) bundle branch block (BBB) were produced with transcardiac needle. After BBB, cycle length (CL) of A-V reentrant PSVT was significantly increased only with ipsilateral sites. Thus, with RBBB, CL of PSVT increased by 37 ± 3 msec., 27 ± 3 msec., and 23 ± 4 msec. (P < 0.001), at AR, LR, and PR sites respectively. With LBBB, CL of PSVT increased only with left-sided sites. Thus, CL increased by 34 ± 2.6 msec., 38 ± 4.6 msec., and 32 ± 3.3 msec., (P < 0.001) with PL, LL, and AL sites, respectively. PSVT CL and septal site did not change significantly after either R or LBBB. The increase in CL was explicable in terms of corresponding increases in intraventricular conduction time (H-Vl). There were slight compensatory decreases in A-H intervals for the increases in H-Vl. These studies confirm findings suggested by clinical electrophysiological observation.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine