The effectiveness of ischemic preconditioning on myocardial protection andcomparison with K+ cardioplegia

The purpose of this study is to investigate the effects of ischemic precond itioning on myocardial protection and to compare this method to K+ crystall oid cardioplegia. Langendorff perfused isolated working rat hearts were use d in the following groups, After 20 min of stabilisation, 30 hearts were di vided into three groups. in group I (control, n = 10), hearts were arrested with cold (+ 4 degrees C) Krebs-Henseleit (K-H) solution, in group II (car dioplegia, n = 10) hearts were arrested with cold K+ cardioplegia solution, and in group III (preconditioning, n = 10) hearts were subjected to 5 min normothermic ischemia followed by 5 min reperfusion then arrested with cold K-H solution. All hearts were subjected to 30 min of global ischemia (24 d egrees C) and 40 min of reperfusion, Hemodynamic measurements were performe d with a left ventricular latex balloon using a data acquisition system, Cr eatine kinase (CK-MB) washout and Troponin I (cTnI) levels were determined from the coronary effluents. There was no significant difference among the three groups in any of the parameters (hemodynamic and biochemical) measure d at the end of stabilisation period. During reperfusion, functional recove ry and coronary flow were significantly improved in K+ cardioplegia and pre conditioned groups compared with control group. CK-MB washout and cTnI leve ls were significantly lower in groups II and III compared with group I at t he reperfusion. However no significant difference was observed between K+ c ardioplegia and preconditioned groups among biochemical and hemodynamic par ameters and coronary flow at the post-ischemic period. In conclusion, ische mic preconditioning is as effective as K+ cardioplegia on myocardial protec tion and recovery of myocardial function during reperfusion. (C) 2000 The I nternational Society for Cardiovascular Surgery. Published by Elsevier Scie nce Ltd. All rights reserved.