VALVE AREA AND CARDIAC-OUTPUT IN AORTIC-STENOSIS - QUANTIFICATION BY MAGNETIC-RESONANCE VELOCITY MAPPING

Valve area and cardiac output were determined with magnetic resonance (MR) velocity mapping in 12 patients with aortic stenosis. Heart cathe rization, Doppler echocardiography, and indicator dilution were perfor med for comparison. Left ventricle could be catheterized in only nine patients; in these cases, MR measured a mean valve area of 1.2 CM2 com pared with 0.9 CM2 derived from catheterization data, with a mean diff erence of 0.2 CM2 between the 2 methods. The limits of agreement were [0.0, +0.5] CM2, less in patients with an important degree of concomit ant regurgitation. In the whole material, MR measured a mean area of 1 .1 CM2 compared with 1.2 CM2 derived from Doppler echocardiography dat a, with a mean difference of 0.1 CM2 and [-0.5, +0.6] CM2 as limits of agreement. In 11 patients the cardiac output was quantified by MR to a mean of 4.9 L/min and by indicator dilution to 5.0 L/min, with a mea n difference of 0.2 L/min, and [-0.6, +0.8] L/min as limits of agreeme nt. In addition, MR offers the major advance of simultaneous quantific ation of regurgitant volume in cases of concomitant regurgitation. In conclusion, because the two important prognostic determinants in aorti c stenosis-the valvular area and the cardiac output-may be quantified, MR has potential to become a clinical tool in assessment of severity in aortic stenosis.