Ischemic preconditioning attenuates myocardial stunning during minimally invasive direct coronary artery bypass grafting (MIDCAB)

Department of Anästhesiologie, Klinik für Anästhesiologie und Operative Intensivm, Kiel, Germany Background and Goal of Study: A brief, controlled period of ischemia is able to exert cardioprotective properties due to a phenomenon called preconditioning [1]. During the MIDCAB-procedure the left anterior descendent coronary artery (LAD) is clamped to enable anastomosis with the left internal mammary artery graft. Thus, depending on the degree of preexisting vessel occlusion, the myocardial tissue is rendered ischemic. A prior LAD clamping in terms of a ischemic preconditioning may be advantageous in preserving left ventricular (LV) function. The myocardial performance index (MPI) derived from echocardiography is a sensitive tool for the assessment of LV function [2]. Materials and Methods: After IRB approval and written informed consent, 39 ASA III patients were randomly assigned to a standard (S, n 20) or a preconditioning (P, n 19) group. In both groups, anaesthesia was performed as total intravenous anaesthesia with propofol and remifentanil. Patients were anaesthetised and operated on always by the same anaesthesiologist and surgeon. In the preconditioning group, LAD was clamped for 2 minutes followed by a 3-minute period of reperfusion prior to definite clamping. Following induction of anaesthesia (baseline) and after definite LAD clamping, the MPI was analysed off-line by a blinded in-vestigator. Additionally, troponin T and CK-MB values were followed up to 72 hours after end of surgery. MPI data and biochemical values at baseline, during LAD clamping and after reperfusion were compared with ANOVA for repeated measures followed by appropiate post testing. Results and Discussion: Demographic data and duration of LAD clamping (S 15.4 min. vs P 14.2 min.) were comparable in both groups. While there were no differences in biochemical markers of myocardial cell damage, the MPI declined significantly (p 0.02) in the standard group during LAD clamping and reperfusion, whereas there was no change in the preconditioning group. Conclusion(s): During LAD clamping myocardial function was better preserved after ischemic preconditioning. In contrast to the reported cardioprotective action of volatile anaesthetics, there was no effect with respect to myocardial cell damage. References: 1 Ann Thorac Surg. 2003; 75(2):709–714. 2 Echocardiography 2002; 19:273–278.