Fr0ysaker T: An ultrasound Doppler technique for the noninvasive determination of the pressure gradient in ti.. Bj0rk-Shiley mitral valve. Circulation 59

SUMMARY The accuracy in determining the pressure gradient in the Bjork-Shiley mitral implant from noninvasive ultrasound Doppler data was explored in nine adult patients. Manometric and ultrasound data were collected simultaneously, and identical diastolic periods were used to compare the manometric gradient (APM) with the gradient obtained from ultrasound data (APu). In the nine patients the mean diastolic value of APM ranged from 2-12.5 mm Hg and the difference between the mean diastolic values of APM and APu was 0.3 ± 1.0 mm Hg (SD). The results of the investigation indicated that the method is accurate and reliable in the noninvasive determination of the mean diastolic gradient in the Bjork-Shiley mitral implant. THE PRESSURE GRADIENT in implanted mitral valves is frequently used in combination with the car-diac output to obtain a quantitative expression for the flow obstruction in the implants. Determination of the gradient requires simultaneous left atrial and left ven-tricular catheterization; a technique that can deter-mine the gradient noninvasively would therefore be a valuable diagnostic tool. Previous reports have described a noninvasive ultra-sound Doppler technique that can determine the pressure gradient in mitral stenosis with an accuracy sufficient for diagnostic purposes.1 2 Noninvasive ul-trasound Doppler data have also been used to evaluate the Bjork-Shiley mitral implant. The results indicated that the gradient in the implant may be determined noninvasively.3 ' In this investigation we explore the accuracy of ultrasound in determining the gradient in the Bj'ork-Shiley mitral implant