The Effects of Cardiac Paci ng in Different Ventricular Sites on Cardiac Work Efficiency in Dogs.

The aim of this investigation was to assess the effects of cardiac pacin g with different ventricular activation sequences on left ventricular function,c oronary blood flow (CBF),myocardial oxygen consumption (MVO 2),and cardiac wo rk efficiency (CWE).Five kinds of ventricular pacing mode including right ventri cular apical pacing (RVA),His Bundle pacing (HisB),left ventricular posterior la teral wall pacing (LVPL),right ventricular apex-left ventricular posterior late ral wall synchronous pacing (RVA-LVPL) and His Bundle-left ventricular posteri or lateral wall synchronous pacing (HisB-LVPL) were performed in 14 healthy adu lt mongrel dogs in randomized orders.Every pacing mode was to capture sinus rhyt hm for 20 min with a 10 min rest period between each of the modes or more after the basic hemodynamic parameters recovering to baseline conditions of original s inus rhythm.All parameters were measured simultaneously during the last 3 minute s before each pacing mode as well as sinus rhythm ended.Results:Cardiac output ( CO),The maximum positive and negative rate of pressure development (+ dp/dt ma x,- dp/dt max),CBF and CWE during HisB,LVPL and HisB-LVPL all increased signi ficantly compared to those during RVA.These parameters indicated no significant difference during HisB,LVPL,and HisB-LVPL compared with one another.CBF enhance d 30%( P 0.05) during RVA-LVPL than that during RVA,while CO,+ dp/dt max,- dp/dt max,and CWE tended to increment but P 0.05.MVO 2 during all modes of cardiac pacing showed no statistical significance compared with one another.C WE increased 17% and 14%( P 0.05) during HisB and HisB-LVPL compared with th at during RVA-LVPL respectively.Conclusion:Based on the short-term study in he althy dogs with cardiac pacing,these data demonstrated that it was a vital thing to normalize ventricular activation synchrony that were beneficial to improve C BF,left ventricular systolic and diastolic function,and CWE.