Preconditioning prevents myocardial stunning after cardiac transplantation

Background. Preconditioning has been shown to reduce myocardial stunning af ter reversible global ischemia. To determine whether preconditioning improv es functional recovery after cardiac transplantation, 16 sheep were randoml y assigned to a preconditioning protocol or to a control group. Methods. Preconditioning was achieved with 5 minutes of global ischemia fol lowed by 10 minutes of reperfusion. The heart was then arrested with 1 L of crystalloid cardioplegia, explanted, stored in a transport cooler, and the n transplanted into recipient sheep. The total ischemia time was 2 hours. P ressure-volume loops were used to calculate preload recruitable stroke work , the maximum elastance, and diastolic compliance. Linear regression analys is was used to determine the preload recruitable stroke work, maximum elast ance, and diastolic compliance-and end-diastolic volume relationship. The a rea under the regression curve for preload recruitable stroke work was defi ned as the preload recruitable stroke work area. Biopsies were taken for hi gh-energy phosphates. Results. Systolic function, represented by preload recruitable stroke work area, was preserved after cardiac transplantation in preconditioned animals . Maximum elastance and diastolic compliance were unaffected by preconditio ning or ischemia. High-energy phosphates were better preserved in precondit ioned animals. Conclusion. Preconditioning prevented myocardial stunning and preserved hig h-energy phosphates after experimental cardiac transplantation. (C) 1998 by The Society of Thoracic Surgeons.