IMPORTANCE OF PRESSURE RECOVERY FOR THE ASSESSMENT OF AORTIC-STENOSISBY DOPPLER ULTRASOUND - ROLE OF AORTIC SIZE, AORTIC-VALVE AREA, AND DIRECTION OF THE STENOTIC JET IN-VITRO

Background Pressure recovery has been shown to occur distal to aortic stenoses in experimental and clinical studies. However, its clinical r elevance in this setting has not yet been evaluated. Methods and Resul ts To address the hypothesis that pressure recovery can cause signific ant differences between Doppler and catheter gradients in aortic steno sis and to examine the effects of aortic size, aortic valve area, and direction of the stenotic jet on these differences, stenoses with valv e areas from 0.5 to 1.25 cm(2) and aortic diameters from 1.8 to 5.0 cm were studied in a pulsatile flow model. Jets entered the aorta centra lly or eccentrically with angles of 15 degrees, 30 degrees, or 45 degr ees. Overall, good correlation was found between Doppler and catheter gradients. However, when the various combinations of orifices and aort as were analyzed separately, slopes varied from 1.0 to 1.86, and the D oppler-catheter gradient differences ranged from -2 (small valve area with a large aorta) to 66 mm Hg (80% overestimation by Doppler echocar diography) when the stenosis was moderate and the aorta was small. Mil d eccentricity of the jet did not significantly alter the results. How ever, overestimation by Doppler decreased with increasing jet eccentri city. Finally, differences between Doppler and catheter gradients coul d be predicted by estimating pressure recovery from Doppler measuremen ts. Conclusions Significant pressure recovery can occur in aortic sten osis and can cause differences between Doppler and catheter gradients. These differences may reach clinical relevance, particularly when the stenosis is moderate and the aorta is small and can be predicted from Doppler measurements.