Pathophysiology of aortic cross-clamping and unclamping

Aortic surgery is associated with a high incidence of perioperative complications, affecting virtually every organ system. The development of these complications is influenced by several factors, including whether surgery was emergent or elective, the location and duration of aortic cross-clamping, and the presence of coexisting disease states. The occurrence of end-organ damage reflects two main processes which are set in motion by aortic cross-clamping. The haemodynamic response refers to the changes produced in preload, afterload, and myocardial contractility. The humoral response refers to the formation and release of a series of mediators that both reflect and cause an ischaemia–reperfusion injury process. A clear understanding of the pathophysiological mechanisms involved in these processes will aid the clinician in adopting a rational approach to the care of patients undergoing aortic surgery.