HEMODYNAMIC EFFECTS OF OUABAIN IN PATIENTS WITH MITRAL STENOSIS AND SINUS RHYTHM

Eight patients with pure mitral stenosis in normal sinus rhythm were studied before and after intravenous administration of 0.5 to 0.7 milligrams of ouabain, by means of simultaneous measurements of cardiac output, oxygen consumption and pressures in the right atrium, pulmonary artery, left atrium, left ventricle and brachial artery. There were no significant changes in heart rate, systemic arterial or right atrial pressure following ouabain. Stroke index increased in all but 1 patient, from 31.4 to 37.5 ml./beat/ M.2 (p < 0.01). Right and left ventricular stroke work index increased by 50 per cent from 12.6 gm.M./beat/M.2 and by 31 per cent from 40.7 gm.M./beat/M.2 (p < 0.01), respectively. Left atrial and ventricular diastolic pressures and mitral valve gradients did not change significantly. Pulmonary arterial pressure increased from 27.6 to 31.0 mm. Hg (p < 0.02), and pulmonary vascular resistance increased consistently by 47 per cent, from 218 dyne sec. cm.-5 (p < 0.01). It is concluded that ouabain exerted a positive inotropic effect upon both the overloaded right and the normal left ventricle and had a small but definite pulmonary vasoconstrictor effect. © 1968.