906-63 Quantitative Doppler Tissue Imaging for the Noninvasive Assessment of Left Ventricular Contractility

Abstract

Doppler Tissue Imaging (DTI) is a new noninvasive imaging modality that allows direct quantitation of myocardial velocity. This study was designed to test the correlation of peak systolic myocardial velocities with other measures of left ventricular (LV) systolic function under conditions of varying contractility. Nine patients with mild or moderate mitral regurgitation (MR) and resting LV ejection fraction (EF) 14 to 70% (41.7 ± 22.2) underwent quantitative DTI of the inferoposterior mid-myocardium. LV dP/dt was estimated from the rate of change of MR velocity on continuous wave Doppler. LV EF, dP/dt and DTI peak systolic velocity (Vel) were measured both at rest and during dobutamine (Dobut) infusion (range 30 to 50 mcg/kg/min, mean 34 ± 7l, and evaluated for change (Δ) from baseline: Rest Dobut Δ p EF(%) 41.7 ± 22.2 56.6 ± 27.9 14.9 ± 8.3 0.001 DTI Vel (mm/s) 22.7 ± 4.2 35.3 ± 10.1 12.6 ± 8.7 0.004 dP/dt (mmHg/ms) 1050 ± 322 1766 ± 768 716 ± 622 0.01 Direct relationships existed between LV dP/dt and both EF (R = 0.78, P = 0.004) and DTI Vel (R = 0.81, P = 0.002). The change in dP/dt during dobutamine infusion compared to baseline exhibited a stronger correlation with change in DTI velocity (R = 0.77) than with change in ejection fraction (R = 0.35). We conclude that 1) both EF and peak systolic myocardial velocity are directly related to LV contractility measured by dP/dt, and 2) catecholamineinduced alteration in myocardial contractility is better reflected by changes in myocardial velocity than by changes in EF. Measurement of myocardial velocity using quantitative DTI may be useful in the noninvasive assessment of ventricular contractility, and may be a useful adjunct to echocardiographic wall motion analysis during catecholamine stress testing.