Left Ventricular Size and Function After Subcutaneous Administration of Terbutaline: Assessment by Cardiac Blood Pool Imaging

Abstract

To assess the response of the left ventricle to subcutaneously administered terbutaline sulfate, a proposed beta-2 selective agonist, we evaluated 12 patients who had suffered previous myocardial infarctions using equilibrium radionuclide angiography. Six patients (group 1) had normal global left ventricular ejection fraction at rest less than 0.49). All patients had a marked decline in end-diastolic volume and end-systolic volume with a significant (P less than 0.01) increase in ejection fraction after terbutaline injection. Cardiac output increased 30 percent in group 2 patients because of an increase in stroke volume, with little change in heart rate (plus or minus 3.1 beats per minute, P equals NS). Cardiac output increased 7 percent in the patients in groups 1, due primarily to an increase in heart rate in 7 beats per minute (+9 percent) with little change in stoke volume. Systemic vascular resistance decreased significantly more in the patients with compensated heart failure than the subjects in group 1 (342 plus or minus 84 vs 90 plus or minus 35 dynes-sec cm(-5), P less than 0.05). We conclude that terbutaline exerts its most beneficial effect on the left ventricle in patients with depressed resting global function, and may prove to be a useful agent in the treatment of congestive heart failure.