Optimizing Pulsatility During Cardiopulmonary Bypass

Cardiac surgery is a high-risk elective surgical procedure frequently requiring CPB in which a machine pumps blood while the surgeon operates on the heart. CPB contributes to surgical risk by causing endothelial dysfunction and acute kidney injury (AKI). Endothelial dysfunction and AKI happen because heart lung machines typically generate non-pulsatile blood flow, which is abnormal and results in impaired tissue oxygen delivery. Normal blood flow is pulsatile due intermittent contraction and relaxation of the heart during the cardiac cycle, which produces a mechanical signal that induces endothelial cells to produce nitric oxide. Without nitric oxide, blood flow does not penetrate as deeply into organs such as the kidneys which leads to acute kidney injury. AKI increases mortality 10-fold after cardiac surgery placing many people at risk since over 400,000 people have surgery with CPB each year in the United States. Thus, pulsatile CPB may influence endothelial function and renal blood flow after cardiac surgery. This study will observe patients undergoing cardiac surgery with CPB and compare patients who receive pulsatile or non-pulsatile CPB.