Evaluation of the Transit Time of Doppler Derived Transmitral A Wave to Left Ventricular Outflow Tract (A-Ar Interval) by Dobutamine Stress Test in Patients with Coronary Artery Disease

Contraction of the left atrium in diastole generates a pressure wave (A) that is initially directed toward the left ventricular apex and is then reflect to the left ventricular outflow tract (Ar). The transit time of the atrial contraction wave to the left ventricular outflow tract (A-Ar interval) is correlated with left ventricular stiffness. We studied the probable relation of the A-Ar interval with coronary artery disease (CAD). To investigate this, 20 patients w ith CAD and 1 O patients with low likelihood of CAD underwent dobutamine Stress Doppler echocardiography. 2D-M mode and Doppler images of all subjects were acquired during peak dobutamine infusion and baseline. Transmitral A wave reflection (Ar) to L VOT was recorded by placing sample volume of 2.5MHz pulsed Doppler imaging transducer between anterior mitral leaflet and L VOT approximately 1- 1.5cm below the aortic cusps in apical five chamber view. The A-Ar interval was determined from the time axis of the spectral profile by measuring the peak-to-peak separation of the A and Ar velocity waves.
RESULTS
There was no significant difference between the baseline Doppler parameters of two groups except A-Ar interval, isovolumetric relaxation time (IVRT) and E wave deceleration rate (E-Dec). A-Ar interval was shorter (49±12 msec. - 61±9 msec., pKeywords: A-Ar interval, coronary artery disease, dobutamine stress test