Semi-automated quantification of the regional left ventricular response to dobutamine stress by Tissue Doppler echocardiography

Tissue Doppler imaging (TDI) may quantify regional left ventricular (LV) function, but extraction of color-coded velocity data has previously required off-line visual comparison to a color velocity map. The objective was to assess the regional LV response to dobutamine stress using a new semi-automated TDI data analysis system. Eight patients, aged 60±12 yrs, with normal posterior wall function at rest and peak stress were studied. Color TDI M-modes (Toshiba 380A) were obtained at rest, at low dose (5 μg/kg/min) and at peak dobutamine stress (45±8 μg/kg/min). Endocardial velocity and time-velocity gradients (TVG) were plotted from a digital velocity matrix (examples shown). Baseline data were: peak systolic velocity 45 ± 22 mm/sec, systolic TVG 3.1 ± 0.9 sec^-1, peak diastolic velocity 68 ± 41 mm/sec, and diastolic TVG 3.8 ± 1.5 sec^-1. Peak systolic and diastolic velocities increased with low dose dobutamine to 66 ± 32*, and 74 ± 31* mm/sec, respectively (*p<0.05 vs. baseline). Further changes occurred at peak stress: peak systolic velocity increased to 106 ± 19 mm/sec*#, systolic TVG increased to 6.8 ± 2.7# sec^-1, peak diastolic velocity increased to 89 ± 36 mm/sec*# and diastolic TVG increased to 6.4 ± 1.4 sec^-1* (* p<0.001 vs. baseline, # p<0.05 vs. low dose). Conclusion: Semi-automated TDI analysis has potential to rapidly quantify regional LV function during dobutamine stress echocardiography.