Surgical procedures result in physiologic stress due to their prothrombotic (pro-clotting) and proinflammatory effects. In turn, those effects increase the risk of a myocardial infarction by promoting clotting in atherosclerotic vessels and releasing inflammatory markers that increase plaque disruption. A prothrombotic event is particularly worrisome for a patient with left main coronary artery stenosis because clotting inside an already diseased coronary artery can cause worsening ischemia (or myocardial infarction) and is the major proximate cause of myocardial infarctions. The proinflammatory state produced by surgery facilitates ischemic events because biochemical substances released into the coronary blood stream cause increased thrombosis, vasospasm, and plaque rupture.
In addition, general anesthesia also significantly increases the risk to patients with severe coronary artery disease due to its attendant hemodynamic stress (blood pressure fluctuations, myocardial depression, etc.). Induction performed at the beginning of general anesthesia is a common cause of hypotension and hemodynamic instability that can lead to an ischemic event.
Surgical physiologic stress medical expert witness specialties include anaesthesiology, general surgery, cardiology, interventional cardiology, cardiovascular surgery, and vascular surgery.