Assessment of Optimal A-V Delay in Dual Chamber Pacing for Acute Ischemic and Non-ischemic Hearts

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  • NAKAGOMI Emiko
    Department of Thoracic and Cardiovascular Surgery, Kyorin University, School of Medicine

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  • 房室ペーシングに対する至適A-V delayの検討 : 特に急性虚血心,非虚血心の検討

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Use of dual chamber pacing (DCP) which can contract the atria is generaly recommended for prevention of decrease in the circulatory output in case of cardiac dysfunction associated with bradycardia. Various problems, however, are involved in the optimal A-V delay to maintain potimal left cardiac functions. Using adult mongrel dogs with experimentaly produced sinus bradycardia and A-V block, the anterior descending branch of the left coronary artery was ligated at a point distal to the bifurcation of the second diagnonal branch to repare acute ischemic hearts with dyskinesis. In this heart, dual chamber pacing was performed and the potimal A-V delay was compared with that of non-ischemic heart. The stroke volume was 101.9±6 % (mean ± SEM) of the value at sinus rhythm at an A-V delay of 100ms for non-ischemic heart and reached the maximum of 91.65% at an A-V delay of 300ms for the acute ischemic heart. This may be explained by the remarkable decrease in contractility of the acute ischemic heart and by reflex of blood to the atria with depressed compliance. In the non-ischemic heart, left ventricular peak dp/dt and stroke word showed changes similar to those for stroke volume. The acute ischemic heart showed no significant changes of left ventricular peak dp/dt or stroke work. These changes may have been offset by dyskinesis. These results indicate that the opeimal A-V delay for dual chamber pacing in acute ischemic heart is more prolonged than that in non-ischemic heart.

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