Short‐ and long‐term dobutamine treatment in chronic ischemic heart failure

This study was undertaken in order to characterize the short‐term (1 hour) and long‐term (72 hours) effect of dobutamine on hemodynamic and regional ejection fraction parameters measured by radionuclear angiography in patients with chronic congestive heart failure due to coronary artery disease. Baseline hemodynamic and radionuclear parameters were measured and then intravenous dobutamine (8.5 ±/kg/min) was administered. The above parameters were determined again after 1 hour and 72 hours of continuous dobutamine administration. Sixty minutes (short‐term) after dobutamine administration heart rate and cardiac index increased significantly (p<0.001 for both) and peripheral resistance decreased concomitantly (p<0.005). Global left ventricular ejection fraction (LVEF) as measured by multigated equilibrium nuclear angiography (MUGA) increased from 21.8±10.6% to 25±13.5 (p<0.02). Count‐based mean regional ejection fraction in the septal, inferoapical, posterolateral (45d̀ left anterior oblique view) and inferior, apical and anterolateral (30d̀ right anterior oblique gated first pass) regions increased also. At 72 hours (long‐term) after continuous dobutamine infusion, heart rate and cardiac index were still significantly higher and peripheral resistance lower than in the control study. However, global and count‐based regional ejection fraction decreased to control values in the right anterior oblique view (first‐pass analysis) and the left anterior oblique view (MUGA). Global LVEF measured in the right anterior oblique view by first‐pass technique was significantly higher than control in the longterm study (23±9.7 vs. 27.8±2.4; p<0.01). The improved global and regional ventricular performances observed in the short‐term, followed by a return to baseline values after long‐term treatment, concomitantly with improved hemodynamic parameters, suggest a relatively short positive inotropic effect of dobutamine and that the effectivity for long term seems to stem, most probably, from the combination of dobutamine's chronotropic effect and its influence upon reducing peripheral resistance (long‐term ventricular loading improved).