DOPPLER-ECHOCARDIOGRAPHIC ASSESSMENT OF PROSTHETIC AORTIC-VALVE AREA - ESTIMATION WITH THE CONTINUITY EQUATION COMPARED TO THE GORLIN FORMULA

Effective orifice area of 3 different designs of prosthetic valves imp lanted in the aortic position was determined by the continuity equatio n and the Gorlin formula using Doppler hemodynamic data. The orifice a rea by the two methods correlated well in the case of tilting disc pro stheses (r = 0.75, P = 0.0001, n = 37, SEE = 0.17 cm(2)) but poorly in the case of bileaflet mechanical valves (r = 0.40, P = 0.17, n = 13) and ball-in-cage prostheses (r = 0.58, P = 0.06, n = 11). Estimation o f prosthetic aortic valve area by the Gorlin formula is inappropriate in the latter two types of prostheses because of design-related variab le empiric constant.