IMPACT OF DOPPLER TISSUE IMAGING IN THE ASSESSMENT OF REGIONAL WALL MOTION ABNORMALITIES IN PATIENTS WITH OLD MYOCARDIAL INFARCTION
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Background: Doppler Tissue Imaging (DTI) is an emerging non-invasive ultrasound technique, which allows measuring velocities at any point of the ventricular wall during the cardiac cycle. Objective: To evaluate the clinical feasibility of DTI as a new method for detection and quantification of regional Wall Motion Abnormalities (WMA) in patients with old Myocardial Infarction (MI). Patients: Fourty patients with old MI who had angiographically-documented significant stenotic lesion in the infarct-related artery and WMA in the infarcted area were evaluated in addition to twenty healthy subjects(control group). Methods: Regional wall motion of each of the anterior and inferior wall segments of the left ventricle was assessed by conventional 2-D echocardiography and pulsed wave DTI. The later includes the measurement of Peak Myocardial Velocity (PMV) and Myocardial Velocity Gradient (MVG). Results: The peak MV and MVG in the studied myocardial segments of control subjects ranged between 4 to 15 cm/s and 1 to 3.85 cmsa respectively. In patients group, Myocardial segments supplied by diseased coronary vessel in the infarcted area were found to have highly significant reduction of both MV & MVG compared to the same segments in control subjects (p<0.001). The sensitivity for detection of WMA was markedly improved by DTI studies (92.5% for MV and 100% for MVG versus 52.5 % for 2-D echo) with retaining the high specificity inherited by conventional echocardiography. Conclusion: Compared to conventional 2-D echo, pulsed wave DTI is an accurate, highly sensitive non-invasive method to detect and quantify regional WMA induced by coronary artery disease. It is almost as accurate as contrast ventriculography in this regard, so it may be the best imaging technique for detection of WMA at rest and with different cardiovascular stresses.