semisynthetic C3 acetyl ester of the aglycone strophanthidin. Acetylstrophanthidin inhibits sodium-potassium adenosinetriphosphatase (Na -K ATPase) and causes an inotropic effect. The effect of acetylstrophanthidin is first seen within half a minute to five minutes and becomes maximal in about ten minutes. This rapid action obviates the effect of time, which is so important for subsidence of precipitationg causes of cardiac failure. Severe pulmonic, coronary, and aortic valvular disease, as well as old age, tended to predispose the patients to unusual acetylstrophanthidin sensitivity. Acetylstrophanthidin may cause nausea and vomiting.