Perioperative assessment of the quality of myocardial protection

Abstract

Perioperative myocardial protection constitutes one of the major advances of modern cardiac surgery, but perioperative assessment of its quality is difficult in clinical practice. This review details our approach to myocardial protection in specific situations, as well as the techniques we use to assess it in three different settings: Is distribution of antegrade cardioplegia homogeneous in patients presenting coronary artery stenosis? The problem was to determine if cardioplegic solutions used antegradely or retrogradely could represent a reliable echographic contrast for myocardial imaging in coronary artery disease patients and normal coronary artery patients, and further if significant differences of myocardial contrast exist between the two methods. Does warm reperfusion cardioplegia improve postoperative myocardial function in patients with an ejection fraction (EF) less than 35%? Pre- and postoperative hemodynamic workup with construction of Starling curves were used to answer this question. Does reperfusion of ischemic hearts induce free radical formation in humans? Deleterious effects of reperfusion are usually determined by studying the effects of free radicals on the myocardium, by determining the concentrations of substances that reflect the degree of membrane phospholipid destruction. However, the specificity and the sensitivity of such assays are low. We recently described white cell chromosomal aberrations secondary to free radical formation, after ischemic and reperfusion injury. Values obtained are expressed as the percentage of the total number of chromosomes. Although specialized laboratory techniques are required, this test is highly accurate.