Relationship between systemic and coronary vascular responses to digoxin and concurrent drug therapy with verapamil/beta-adrenoceptor antagonists in humans.

Abstract

1. In 24 patients who were undergoing coronary arteriography for the assessment of ischaemic heart disease, the relationship between the systemic and coronary vascular responses to acute intravenous digoxin administration (500 micrograms) and concurrent drug therapy with the calcium antagonist verapamil (group I) or a beta-adrenoceptor antagonist (group II) or neither of these agents (group III) was examined. 2. Systemic vascular resistance (SVR) tended to rise rapidly after digoxin injection in patients in groups II and III, and tended to decline initially in patients in group I; however, these differences were not statistically significant (variance ratio [VR] = 0.77). 3. No significant differences were observed in coronary vascular responses to acute digoxin administration between the three groups of patients (VR = 0.34). 4. For the entire group of 24 patients, no statistically significant digoxin-induced effects on resistance could be demonstrated in either the systemic or coronary circulations, although in individual patients vasoconstrictor effects were observed. 5. We conclude that acute intravenous administration of digoxin does not consistently cause systemic or coronary vasoconstriction in patients with ischaemic heart disease. Variability in vasomotor responses to digoxin is not clearly related to concurrent drug therapy with verapamil or a beta-adrenoceptor antagonist. The observation that systemic vascular resistance tends to increase in the first few minutes after digoxin injection should be addressed in future studies.