ISCHEMIC PRECONDITIONING AS AN ADJUNCT TO CRYSTALLOID OR BLOOD CARDIOPLEGIA FOR MYOCARDIAL PROTECTION IN ROUTINE CORONARY SURGERY

Experimental preconditioning is commonly regarded as a powerful protec tive phenomenon in case of subsequent ischemia. However, little is kno wn about the applicability of preconditioning as an adjunct to cardiop legic myocardial protection in routine coronary surgery. For this reas on, a prospective clinical study (6/1995 to 4/1996) was initiated to e valuate normothermic ischemic preconditioning prior to crystalloid or cold blood cardioplegic arrest. Preconditioning was performed in two c ycles of 5 min ischemia and 10 min reperfusion. Four groups of 7 patie nts each were compared regarding release of troponin T, creatine kinas e-myocardial isoform (CK-MB), lactate, and total CK in coronary sinus effluents over a 12-hour period. In the absence of perioperative myoca rdial infarction, there were no significant differences in these ische mic and metabolic parameters. Unexpectedly, the heed of postoperative pharmacological inotropic support was greater after preconditioning. T hese results may indicate that ischemic preconditioning as an adjunct to cardioplegic arrest may be associated with impairment of left-ventr icular contractility, thus even exerting potentially detrimental funct ional effects. Overall, the proven beneficial effects of experimental preconditioning seem not to be directly transferable into the clinical settings.