SUPERIORITY OF END-DIASTOLIC VOLUME AND EJECTION FRACTION MEASUREMENTS OVER WEDGE PRESSURES IN EVALUATING CARDIAC-FUNCTION DURING AORTIC RECONSTRUCTION

Marked changes occur in cardiac function during aortic reconstruction. Numerous factors (primarily compliance changes) limit the currently used pressure-based pulmonary artery catheters' ability to reflect these changes accurately. A new pulmonary artery catheter was used in 26 patients undergoing aortic reconstruction (7 patients with abdominal aortic aneurysms and 19 with occlusive disease) that directly measures right ventricular (RV) volumes and ejection fractions. The extent of coronary artery disease (CAD) was evaluated before surgery, and the patients were divided into three classes. The greatest changes in cardiac function were noted immediately after aortic cross-clamping. Cardiac output significantly decreased in patients with mild or moderate CAD (p < 0.01 and p < 0.001) but not in patients with no CAD (p > 0.5). This correlated well with RV end-diastolic volume (RV-EDV) and stroke volume (RV-SV) measurements in the groups with mild (p < 0.05) and moderate CAD (p < 0.01) but not in the group with no CAD (p > 0.5). Wedge pressure showed poor correlation, with no significant change noted in any group (p > 0.5). Measurements taken later in the procedure documented a significant trend toward baseline in mild and moderate groups. At the opening of the second limb of the graft, the compensated values (CO, RV-EDV, and RV-SV) did not change significantly in the groups with mild and no CAD (p > 0.2) but approached significance in the group with moderate CAD (p < 0.08). These data indicate that changes in cardiac indexes with aortic cross-clamping correlate directly with the degree of CAD and are not reflected by the wedge pressure. RV-EDV and RV-SV provide a better means to evaluate the cause of decreased cardiac output (volume vs contractility) during surgery and direct appropriate intervention. Widespread use of this monitoring technique may reduce the morbidity and mortality rates in high-risk patients undergoing aortic reconstruction.