Assessment of Myocardial Performance and Optimal Volume Loading During Elective Abdominal Aortic Aneurysm Resection

Myocardial depression has been suggested as a cause of declamping hypotension. To investigate and manage this problem, thermal dilution catheters were placed in 22 elderly, high-risk patients (mean age 71 years) who underwent elective abdominal aortic aneurysm resection. There were no deaths. Myocardial performance curves (MPC) were determined preoperatively, following induction of anesthesia, during aortic clamping, following declamping, and 12 to 48 hours postoperatively. The slope of this curve was taken as an index of myocardial performance. Preoperative cardiac index at a pulmonary artery wedge pressure of 10 mm Hg (CI10) decreased significantly following induction of anesthesia (P less than .002) and persisted during aortic cross-clamping. Following declamping, CI10 rose to preoperative levels. The slope of the MPC followed this same pattern. There was no significant change in blood pressure with the aorta clamped or following declamping. Myocardial performance is depressed following induction of anesthesia but declamping hypotension can be minimized or prevented by optimum volume loading as guided by Starling's myocardial performance curves.