A new method to calculate aortic valve area without left heart catheterization

Abstract

Assessment of the severity of aortic stenosis remains a commonly encountered clinical problem. Noninvasive evaluation has to date not proven sufficiently accurate in most cases to permit clinical decision making in the individual patient. Therefore, cardiac catheterization and measurement of the valve area with use of the Gorlin equation remains the standard approach in patients with suspected aortic stenosis. Doppler ultrasound allows direct measurement of blood velocity in cardiac chambers. This technique was used to study 16 patients with suspected aortic stenosis after cardiac catheterization. Aortic valve area (AVA) was calculated with the equation AVA = CO/(SEP X mean velocity), where CO is cardiac output measured by thermodilution and SEP is the systolic ejection period derived from the Doppler tracings. The resulting value was compared with valve area calculated from cardiac catheterization data and an excellent correlation was noted (r = .99). This study demonstrates that Doppler ultrasound can be used to accurately measure aortic valve area without the need for left heart catheterization.