Quantitative analysis of myocardial response to dobutamine by measurement of left ventricular wall motion using omnidirectional M-mode echocardiography

Although dobutamine stress echocardiography is important for assessing cardiac ischemia and viability, analysis of wall motion is qualitatively performed. We quantitatively evaluated left ventricular wall motion using a newly developed omnidirectional M-mode echocardiography that can depict the M-mode at the site of region of interest on the 2-dimensional image in real time, and established its usefulness for analyzing the myocardial response to dobutamine infusion. Dobutamine stress echocardiography with omnidirectional M-mode was performed in 57 patients with coronary lesions. In 38 of these patients, exercise stress single-photon emission computed tomographic thallium scintigraphy (Tl-201 SPECT) was performed. Endocardial excursion of 103 regions was measured from omnidirectional M-mode at baseline, low-dose (6 μg/kg/min), and at peak dose (30 μg/kg/min) dobutamine. A decrease and increase in wall excursion was scored (from −3 to 3) for a changes of every 2 mm, and a quantitative wall motion score (QWMS) was calculated as a summation of the scores from baseline to low dose and from low to peak doses. Quantitative coronary stenosis score (QCSS) was calculated as a summation of stenotic and collateral scores. The stenosis scores were graded as: 1 = 0% to 50%, 2 = 50% to 75%, 3 = 75% to 90%, 4 = 90% to 95%, 5 = 95% to 100%; collateral scores were graded as: −1 = poor collateral, −2 = good collateral. Based on the QWMS at each dose of dobutamine, the serial changes in wall motion were divided into 4 groups: augmented, biphasic, no change, and worsening. The QCSS was clearly different among these groups. QWMS was significantly correlated with QCSS (r = 0.657, p <0.001). The incidence of redistribution in Tl-201 SPECT was high in the region with low score of QWMS. In conclusion, omnidirectional M-mode is useful for quantitatively determining the grade of cardiac ischemia by assessing the serial change of ventricular wall motion during dobutamine infusion.