Assessment of cardiovascular function in patients undergoing coronary artery bypass grafting.

Blood pressure and flow in the ascending aorta were measured in 16 patients undergoing coronary artery bypass grafting. The analog records were digitized and the data used to compute total hemodynamic power and aortic input impedance, which may be considered to be direct indices of cardiac performance and the state of the cardiovascular system. Various indirect indices were also computed from the same data and statistically compared with the two direct indices. The results showed that it is necessary to measure both pressure and flow to achieve statistically significant correlations, and that none of the indirect indices was capable of describing either cardiac performance or the state of the cardiovascular system comprehensively, or unambiguously, in these patients.