Ischemic preconditioning does not acutely improve load-insensitive parameters of contractility in in vivo stunned porcine myocardium

Objective: Ischemic preconditioning has been shown to have no beneficial ef fect on segment shortening in in vivo regionally stunned myocardium, The pu rpose of this study was to determine whether ischemic preconditioning impro ves the recovery of postischemic ventricular function when contractility is assessed by load-insensitive measurements including end-systolic pressure length relations, preload recruitable stroke work, and preload recruitable stroke work area in in vivo regionally stunned porcine myocardium. Methods: Open chest, pentobarbital-anesthetized pigs were used. Regional ventricula r function was monitored by measurements of segment shortening, stroke work , end systolic pressure length relations, preload recruitable stroke work, and preload recruitable stroke work area. The control group was submitted t o 15 minutes of left anterior descending coronary artery occlusion and 3 ho urs of reperfusion, The preconditioned group underwent 2 cycles of 5-minute left anterior descending coronary artery occlusion and 10-minute reperfusi on before 15 minutes of occlusion, Results: There was no infarct in either group. The preconditioning protocol significantly depressed preischemic seg ment shortening but not regional stroke work, Ischemic preconditioning had no significant beneficial effect on regional stroke work, end-systolic pres sure length relations, preload recruitable stroke work, or preload recruita ble stroke work area. Conclusions: These results confirm that ischemic prec onditioning does not ameliorate in vivo porcine myocardial stunning and ind icate that ischemic preconditioning may have a limited cardioprotective rol e during cardiac operation.