DETERMINATION OF AORTIC-VALVE AREA IN VALVULAR AORTIC-STENOSIS BY DIRECT MEASUREMENT USING INTRACARDIAC ECHOCARDIOGRAPHY - A COMPARISON WITH THE GORLIN AND CONTINUITY EQUATIONS

Objectives. This study sought to 1) show that intracardiac echocardiog raphy can allow direct measurement of the aortic valve area, and 2) co mpare the directly measured aortic valve area from intracardiac echoca rdiography with the calculated aortic valve area from the Gorlin and c ontinuity equations. Background. Intracardiac echocardiography has bee n used in the descriptive evaluation of the aortic valve; however, dir ect measurement of the aortic valve area using this technique in a cli nical setting has not been documented. Despite their theoretical and p ractical limitations, the Gorlin and continuity equations remain the c urrent standard methods for determining the aortic valve orifice area. Methods. Seventeen patients underwent intracardiac echocardiography f or direct measurement of the aortic valve area, including four patient s studied both before and after valvuloplasty, for a total of 21 studi es. Immediately after intracardiac echocardiography, hemodynamic data were obtained from transthoracic echocardiography and cardiac catheter ization. Results. Adequate intracardiac echocardiographic images were obtained in 17 (81%) of 21 studies. The average aortic valve area (mea n +/- SD) determined by intracardiac echocardiography for the 13 studi es in the Gorlin analysis group was 0.59 +/- 0.18 cm(2) (range 0.37 to 1.01), and the average aortic valve area determined by the Gorlin equ ation was 0.62 +/- 0.18 cm(2) (range 0.31 to 0.88). The average aortic valve area determined by intracardiac echo cardiography for the 17 st udies in the continuity analysis group was 0.66 +/- 0.23 cm(2) (range 0.37 to 1.01), and that for the continuity equation was 0.62 +/- 0.22 cm(2) (range 0.34 to 1.06). There was a significant correlation betwee n the aortic valve area determined by intracardiac echocardiography an d the aortic valve area calculated by the Gorlin (r = 0.78, p = 0.002) and continuity equations (r = 0.82, p < 0.0001). Conclusions. In the clinical setting, intracardiac echocardiography can directly measure t he aortic valve area with an accuracy similar to the invasive and noni nvasive methods currently used. This study demonstrates a new, quantit ative use for intracardiac echocardiographic imaging with many potenti al clinical applications.