Nitroprusside and mitral stenosis.

Abstract

The cardiovascular effects of an intravenous nitroprusside infusion were evaluated intraoperatively in seven patients with pure mitral stenosis and seven patients with predominant mitral stenosis. Prior to therapy the adverse hemodynamic consequences of light anesthesia and surgical stimulation were evident in all patients: systemic and/or pulmonary hypertension were present, systemic vascular resistance was twice normal, and cardiac function was depressed. Nitroprusside consistently reduced systemic vascular resistance and systemic arterial as well as pulmonary arterial and wedge pressures, but cardiac index increased only when severe pulmonary hypertension and/or some mitral regurgitation coexisted with mitral stenosis. In the group with predominant mitral stenosis, cardiac index increased from 1.8 to 2.1 L/min/m2 with nitroprusside (p < 0.05). In three individuals who demonstrated severe pulmonary hypertension (one with pure mitral stenosis and two with predominant mitral stenosis), nitroprusside induced an increase of almost 50% in cardiac index and stroke volume. In contrast, patients with pure mitral stenosis and mild pulmonary hypertension showed little change in cardiac index or stroke volume. It is concluded that nitroprusside can safely be used to control systemic or pulmonary hypertension during anesthesia and surgery in patients with mitral stenosis and that if severe pulmonary hypertension and/or mitral regurgitation coexist with mitral stenosis, cardiac function will also improve.