Copyright © 1984 by the European Society of Cardiology.
© 1984 The European Society of Cardiology
An orifice formula independent of mitral pressure gradient for the evaluation of prosthetic mitral valve obstruction
Cardiovascular Research Institute, University of California, School of Medicine San Francisco, California
Division of Cardiology, University of Oregon, School of Medicine Portland, Oregon, U.S.A.
Received 21 March 1983; revised 26 July 1984; .
Address for Correspondence: W. S. Seitz, M.D, Cardiovascular Research Institute, University of California, School of Medicine, San Francisco, CA 94143, U.S.A.
Abstract
We have studied an hydraulic orifice equation capable of quantifying the obstructive properties of mitral prostheses from data of a potentially less invasive nature than is required by conventional methods. The results indicate that effective prosthetic orifice area may be computed by the pressure independent equation A = 21SV/DFP2, where A is the effective prosthesis orifice area in cm2, SV is the stroke volume in ml and DFP is the diastolic filling period in s min1. Areas computed with the pressure independent equation correlate with the results of the modified Gorlin formula (given in the appendix) at a level of r = 0.91 for a series of 17 cases within a range of effective value areas of 0.50 cm2 to 1.60 cm2. These results suggest that simplified nontraumatic procedures may be developed to screen and follow patients with prosthetic value implants.
Key Words: Mitral prostheses orifice formula obstruction