Studies on Digitalis

Abstract

The efficacy of cardiac glycosides was evaluated in eight symptomatic patients with pure mitral stenosis in normal sinus rhythm and in three patients in atrial fibrillation. The patients were studied at rest and during moderate and intense levels of treadmill exercise before and after the acute intravenous administration of ouabain. During maximal exercise ouabain slowed the ventricular rate considerably in two of the three patients in atrial fibrillation, and this reduction was associated with significant hemodynamic improvement. However, in the patients in sinus rhythm ouabain produced no significant change in heart rate and had no beneficial effect on cardiac output, oxygen consumption or severity of pulmonary hypertension either at rest or during exercise. Since patients with pure mitral stenosis in normal sinus rhythm are not benefited by the acute administration of ouabain, there is a reasonable doubt whether the routine use of digitalis in the medical management of such patients is advisable.