Vasoplegia After Cardiovascular Procedures—Pathophysiology and Targeted Therapy

Vasoplegic syndrome, characterized by low systemic vascular resistance and hypotension in the presence of normal or supranormal cardiac function, is a frequent complication of cardiovascular surgery. It is associated with a diffuse systemic inflammatory response and is mediated largely through cellular hyperpolarization, high levels of inducible nitric oxide, and a relative vasopressin deficiency. Cardiopulmonary bypass is a particularly strong precipitant of the vasoplegic syndrome, largely due to its association with nitric oxide production and severe vasopressin deficiency. Postoperative vasoplegic shock generally is managed with vasopressors, of which catecholamines are the traditional agents of choice. Norepinephrine is considered to be the first-line agent and may have a mortality benefit over other drugs. Recent investigations support the use of noncatecholamine vasopressors, vasopressin in particular, to restore vascular tone. Alternative agents, including methylene blue, hydroxocobalamin, corticosteroids, and angiotensin II, also are capable of restoring vascular tone and improving vasoplegia, but their effect on patient outcomes is unclear.