MYOCARDIAL RESPONSE TO ACETYL STROPHANTHIDIN IN CONGESTIVE HEART FAILURE: A STUDY OF ELECTROLYTES AND CARBOHYDRATE SUBSTRATES*

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Abstract
Preliminary to an examination of the myocardial metabolic changes induced by acetyl strophanthidin, the hemodynamic effect of 1.1 mg intravenously was studied in 5 patients with low-output heart failure. A substantial stroke work increase occurred within 5 minutes, becoming maximal at nearly twice the control level by 15 minutes and declining in 25 minutes. The same rapid mode of administration was employed in 18 patients with cardiac failure in whom myocardial extractions of electrolytes and carbohydrate substrate were determined by paired arterial and coronary sinus sampling. The significantly greater increment in coronary sinus potassium, usually maximal within 4 minutes, indicated a net myocardial loss of this ion which was not counteracted by a directional reversal of this ionic movement during the observation period. This phenomenon was not quantitatively related to the stroke work response and was not, with one exception, associated with toxic electro-cardiographic manifestations. No significant changes were observed in the extractions of sodium, calcium, glucose and pyruvate. Lactate extraction became substantially reduced 15 minutes after the drug. The possible relationship of this finding to potassium egress from the heart was considered.