The Acute Hemodynamic Effect of Various Cardiac Pacing Modes in Dogs.

We observed the acute changes of hemodynamics and cardiac mechanics during five kinds of pacing mode in order to assess the effect of atrio ventricular synchrony and ventricular activation sequence.Five kinds of pacing mode including RAP,AHSP,AVSP,HBP and RVP were performed in ten dogs at random,and hemodynamic parameters and cardiac mechanical parameters were measured after stable pacing was achieved for 5 minutes.Results:RAP and AHSP showed no significant change on hemodynamics.During AVSP,CO,+dp/dt max ,and -dp/dt max decreased 16.32%,15.01%,and 15.19% respectively.During HBP,there showed an increment of mPAP,PCWP and LVEDP,and CO decreased 14.93%.During RVP,there showed an increment of mPAP,PCWP and LVEDP,and CO,+dp/dt max ,and -dp/dt max decreased 23.95%,22.28%,and 19.74% respectively.Conclusion:Loss of AV synchrony affect global systolic function by the change of LV preload,and abnormal ventricular activation sequence decreases both of the left ventricular systolic and diastolic function.It is important for us to preserve AV synchrony and normal ventricular activation sequence in cardiac pacing.