Objective To compare the effects of biventricular synchronous pacing with different pacing site on coronary Blood flow (CBF), myocardial oxygen consumption (MVO₂) and cardiac work efficiency (CWE).

Methods RA-cHisB and RA-RVA sequential pacing, RVA-LVPL and cHisB-LVPL pacing, RA-RVA-LVPL and RA-cHisB-LVPL pacing were randomly performed in 14 dogs with general-anaesthetised, opened chest and artificial-ventilation. SNR was as self-control. Every pacing mode was to capture SNR for 20 min with a recovery of physiologic parameters for 10 min, and then shift another pacing mode in turn. CFB and CO were measured by a electromagnetic flowmeter. Blood sample were respectively collected from the catheters in left ventricle and coronary sinus for getting the arterial O₂ saturation (SaO₂), coronary sinus O₂ saturation (ScsO₂) and Hgb.

Results No significant difference in CBF among the RA-cHisB-LVPL, RA-RVA-LVPL and RA-cHisB pacing were found. CBF in RA-RVA pacing was decreased than that in RA-cHisB-LVPL, RA-RVA-LVPL and RA-cHisB pacing. MVO₂ among the all groups had no significant changes compared with each other. CO of RA-cHisB, RVA-LVPL and cHisB-LVPL pacing were increased as compared with that in RA-RVA pacing (p<0.01). CO in cHisB-LVPL pacing was increased by 6.7% than that in RVA-LVPL pacing. CO in RA-cHisB pacing was increased by 8.7% than that in RA-RVA pacing. CO in RA-RVA-LVPL pacing was increased as compared with that in RA-cHisB and cHisB-LVPL pacing, respectively. CO in RA-cHisB-LVPL pacing was increased than that in RA-RVA-LVPL pacing. The changes of CWE were similar to that of CO among all pacing groups. CWE in RA-cHisB-LVPL pacing was significantly enhanced as compared with that in RA-cHisB and RA-RVA-LVPL pacing. Conclusions RA-cHisB dual chamber, cHisB-LVPL biventricular and RA-cHisB-LVPV triple-chamber pacing might significantly increase CBF and CWE without the increment of MVO₂.

Conclusion The biventricular synchronous pacing have the beneficial effects on maintaining the balance between myocardial oxygen supply and consumption and increasing CWE by enhancing the cardiac ejection performance.