Influence of acute volume loading on right ventricular function after cardiopulmonary bypass

The influence of acute volume loading on right ventricular function immediately after extracorporeal circulation (ECC) was investigated in 25 patients undergoing elective aortocoronary bypass grafting. In addition to commonly monitored hemodynamic variables, right ventricular (RV) ejection fraction (EF) was measured by thermodilution technique using a new fast-response thermodilution catheter. In eight patients with concomitant severe stenosis (greater than 89%) of the right coronary artery (RCA), volume loading was followed by a decreased RVEF and cardiac output. In contrast, RVEF in the 17 patients without diseased RCA increased significantly, with an increase in cardiac output. Duration of aortic cross-clamping (i.e., ischemia) was more pronounced in the group with decreased RVEF due to RCA grafting. Increased end-diastolic volume and decreased RV contractility index indicated that patients with myocardial ischemia during cardiac surgery procedures sometimes were unable to make the adaptations required. We conclude that cardiocirculatory dysfunction associated with ECC may be caused by depressed RV function. Acute volume loading in this situation may lead to further deterioration of myocardial function due to RV failure, a condition which cannot be diagnosed readily at the bedside with the usual monitoring techniques.