Right ventricular dysfunction following cold potassium cardioplegia

Right coronary artery stenoses limit cardioplegic delivery to the right ventricle and may contribute to postoperative right ventricular dysfunction. Right ventricular function was evaluated in 39 patients with right coronary artery stenoses following elective coronary bypass operations. Hemodynamic and nuclear ventriculographic measurements, made between 3 and 6 hours postoperatively, revealed a progressive increase in pulmonary arterial pressure, pulse rate, and right ventricular ejection fraction (p less than 0.05). Right ventricular end-diastolic volume index (calculated from the thermodilution stroke index divided by the nuclear ejection fraction) decreased, but right atrial pressure increased (suggesting a decrease in compliance). The response to the infusion of 2 units of plasma (volume loading) was evaluated 3 hours postoperatively (EARLY) and again 5 hours postoperatively (LATE) in 21 patients. Right ventricular performance (the relation between cardiac index or right ventricular stroke work index and right ventricular end-diastolic volume index) and right ventricular systolic function (the relation between systolic pulmonary arterial pressure and right ventricular end-systolic volume index) were depressed EARLY and improved LATE (p less than 0.01 in analysis of covariance). Left ventricular performance (the relation between cardiac index or left ventricular stroke work index and left ventricular end-diastolic volume index) and left ventricular systolic function (the relation between systolic blood pressure and left ventricular end-systolic volume index) were similar EARLY and LATE. Right ventricular diastolic function (the relation between right atrial pressure and right ventricular end-diastolic volume index) and left ventricular diastolic function (the relation between left atrial pressure and left ventricular end-diastolic volume index) were significantly greater LATE than EARLY. Right, but not left, ventricular performance and systolic function were transiently depressed, and right and left ventricular diastolic stiffness were transiently decreased in the EARLY postoperative period. In patients with right coronary artery stenoses, current methods of cardioplegia may inadequately protect the right ventricle, but further studies are required to establish the relation between intraoperative protection and postoperative function.