AORTIC-VALVE PRESSURE-GRADIENTS IN PATIENTS WITH AORTIC-VALVE STENOSIS - QUANTIFICATION WITH VELOCITY-ENCODED CINE MR IMAGING

OBJECTIVE. Pressure gradients across the aortic valve due to stenosis of the valve must be measured accurately to evaluate the functional se verity of the stenosis. Velocity-encoded cine MR has been used to quan tify blood flow and flow direction and, more recently, the regurgitant fraction in aortic regurgitation. The purpose of this study was to de termine the feasibility and accuracy of velocity-encoded cine MR for e stimating pressure gradients across the aortic valve in patients with aortic stenosis. SUBJECTS AND METHODS. We used velocity-encoded cine M R to measure flow velocity and determine pressure gradients across the aortic valve in 19 subjects. The pressure gradient (DELTAP) was estim ated from the simplified Bernoulli equation by using the maximum insta ntaneous aortic jet velocity (V(max)): DELTAP (mm Hg) = 4V2max (m/sec) . RESULTS. Maximum and mean systolic pressure gradients determined by using velocity-encoded cine MR were 3-148 mm Hg and 2-87 mm Hg, respec tively, for all subjects. The pressure gradients correlated closely wi th gradients determined by using established methods: Doppler echocard iography and cardiac catheterization. Correlation coefficients (r) wer e .96 (y = 0.94x - 1.9) and .97 (y = 0.97x + 0.5), respectively. CONCL USION. We conclude that velocity-encoded cine MR imaging provides a no ninvasive and accurate means for quantifying the severity of valvular aortic stenosis. MR is a feasible method for determining pressure grad ients across the aortic valve.