Abstract
Experimental preconditioning is commonly regarded as a powerful protective phenomenon
in case of subsequent ischemia. However, little is known about the applicability of
preconditioning as an adjunct to cardioplegic myocardial protection in routine coronary
surgery. For this reason, a prospective clinical study (6/1995 to 4/1996) was initiated
to evaluate normothermic ischemic preconditioning prior to crystalloid or cold blood
cardioplegic arrest. Preconditioning was performed in two cycles of 5 min ischemia
and 10 min reperfusion. Four groups of 7 patients each were compared regarding release
of troponin T, creatine kinase-myocardial isoform (CK-MB), lactate, and total CK in
coronary sinus effluents over a 12-hour period. In the absence of perioperative myocardial
infarction, there were no significant differences in these ischemic and metabolic
parameters. Unexpectedly, the heed of postoperative pharmacological inotropic support
was greater after preconditioning. These results may indicate that ischemic preconditioning
as an adjunct to cardioplegic arrest may be associated with impairment of left-ventricular
contractility, thus even exerting potentially detrimental functional effects. Overall,
the proven beneficial effects of experimental preconditioning seem not to be directly
transferable into the clinical settings.
Key words
Ischemic preconditioning - Coronary surgery - Cardioplegia
