[Comparative assessment of variants of potassium crystalloid cardioplegia]

Sixty eight patients operated on for valvular abnormalities were examined. In Group 1 (n = 34) myocardial protection was made by potassium solutions containing different potassium concentrations: 30 mM and 5 mM for induction and reinfusion, respectively. In Group 2 (n = 34) a hyperosmolar oxygenized cardioplegic solution containing K+, 15 mM, and Mg2+, 16 mM was administered under the same conditions. In the early postoperative period, no differences were found in the frequency and size of inotropic support, as evidenced by central hemodynamic parameters. ECG showed that in Group 2 there was a reduction in the frequency of changes of S-T segment, indicating the presence of myocardial ischemic changes. A 24-hour Holter monitoring demonstrated that life-threatening ventricular arrhythmias occurred significantly more infrequently in Group 2. The ultrastructural study of intraoperative biopsy specimens of the myocardium, including their treatment with colloid lanthanum showed that the tracer had penetrated virtually into all cardiomyocytes at the peak of ischemia and reperfusion in Group 1. In Group 2, ultrastructural changes were less profound and the particles of the tracer lanthanum had penetrated into the sarcoplasm of 15% of cells. Inadequate myocardial protection cannot be regarded as a cause of one of three deaths from acute heart failure. The studies demonstrated that crystalloid potassium cardioplegia was highly effective. However, the possibility of additionally affecting the permeability of a cell membrane by changing the solution composition (elevating magnesium concentrations) and the reduction of frequency of cardiac arrhythmias suggest that each components of the cardioplegic solution should be studied.