Effect of dobutamine on regional left ventricular function measured by tagged magnetic resonance imaging in normal subjects

The effect of inotropic stimulation on the pattern and magnitude of regiona l left ventricular contraction was studied using tagged magnetic resonance imaging to assess whether dobutamine exacerbates variation in regional cont raction at rest. Dobutamine stress testing defines a normal response as a h omogeneous increase in regional wall motion. in 8 normal subjects, 4 equall y spaced left ventricular short-axis levels were imaged through systole usi ng tagged magnetic resonance imaging. The baseline imaging sequence was rep eated with 5-, 10-, 15-, and 20-mu g/kg/min dobutamine infusion. Regional m yocardial displacement redial thickening, and circumferential shortening we re measured. The left ventricle was analyzed by level (base to apex) and wa ll (septum, inferior, lateral, anterior), Dobutamine did not alter baseline regional functional heterogeneity. Dobutamine infusion resulted in a unifo rm increase in displacement, radial thickening, and circumferential shorten ing from baseline to 10-mu g/kg/min infusion without additional increases a t higher doses. (C) 1999 by Excerpta Medica, Inc.