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 effect on segment shortening in in vivo regionally stunned myocardium. The purpose of this study was to determine whether ischemic preconditioning improves 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 ventricular 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 to 15 minutes of left anterior descending coronary artery occlusion and 3 hours of reperfusion. The preconditioned group underwent 2 cycles of 5-minute left anterior descending coronary artery occlusion and 10-minute reperfusion before 15 minutes of occlusion.


RESULTS
There was no infarct in either group. The preconditioning protocol significantly depressed preischemic segment shortening but not regional stroke work. Ischemic preconditioning had no significant beneficial effect on regional stroke work, end-systolic pressure length relations, preload recruitable stroke work, or preload recruitable stroke work area.


CONCLUSIONS
These results confirm that ischemic preconditioning does not ameliorate in vivo porcine myocardial stunning and indicate that ischemic preconditioning may have a limited cardioprotective role during cardiac operation.
Jahania
M S
MS
Department of Surgery, University of Kentucky College of Medicine, Lexington, KY, USA.
Lasley
R D
RD
Mentzer
R M
RM
D000818:Animals; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D019157:Ischemic Preconditioning, Myocardial; D009200:Myocardial Contraction / Q000502:physiology*; D017682:Myocardial Stunning / Q000503:physiopathology / Q000628:therapy*; D011897:Random Allocation; D013318:Stroke Volume / Q000502:physiology; D013552:Swine; D013997:Time Factors; D016276:Ventricular Function / Q000502:physiology