Assessment of myocardial performance and optimal volume loading during elective abdominal aortic aneurysm resection
H. L. Bush Jr, F. W. LoGerfo, R. D. Weisel, J. A. Mannick and H. B. Hechtman
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.
