Examination of Left Ventricular Contractile Reserve by Doppler Myocardial Imaging in Patients with Dilated Cardiomyopathy

Detection of left ventricular contractile reserve by means of dobutamine stress echocardiography is a well known technique. The aim of the present study was to detect velocity changes during the administration of dobutamine, to establish if Doppler myocardial imaging is a suitable method for determining left ventricular contractile reserve, and to determine if the technique provides more information than traditional stress echocardiography. Twenty-five patients (all males; mean age, 53.4 years) were examined for a clinical diagnosis of idiopathic dilated cardiomyopathy with a poor left ventricular systolic function (ejection fraction less than 30%). Doses of 5-10 and 20 mg/kg/min dobutamine were administered and elevated at 4-minute intervals. Ejection fraction was calculated using the Simpson rule. The peak systolic and the early and late diastolic velocities were measured in the basal segment of the septum and the inferior wall at baseline and at full dose of dobutamine. Results indicated that peak systolic velocity increased significantly, both in the septum (0.11±0.03 vs. 0.20±0.05 m/sec; p=0.001) and in the inferior wall (0.10±0.05 vs. 0.17±0.06 m/sec; p=0.03). Late diastolic velocities also increased significantly, both in the septum (0.17±0.05 vs. 0.22±0.07 m/sec; p=0.01) and in the inferior wall (0.18±0.08 vs.0.21±0.02 m/sec; p=0.01). There was a significant linear correlation between the relative increases in basal ejection fraction value and in peak systolic velocity upon dobutamine stimulation. Patients were divided into responders and nonresponders based on responses in either ejection fraction (25% relative increase) or peak systolic velocity (5 cm/s increase). This study concludes that 1) Doppler myocardial imaging is an adequate and simple technique to examine left ventricular contractile reserve; and 2) measurement of peak systolic velocity during dobutamine stimulation seems to be a simple and good indicator of left ventricular contractile reserve.