The experimental relationship between leaflet clearance and orientation of the St. Jude Medical valve in the mitral position.

Abstract

The optimal orientation of the St. Jude Medical mechanical prosthesis in the mitral position has not yet been determined. While in the majority of cases the valve can perform satisfactorily regardless of valve orientation, certain circumstances can increase the risk of leaflet impingement. These valves are commonly implanted with their leaflets oriented parallel to the anatomic axis of the native leaflets (anatomic orientation) or with their prosthetic leaflets perpendicular to the axis of the native leaflets (antianatomic orientation). To determine the influence of valve orientation on the clearance from the prosthetic leaflet to the posterior ventricular wall, we calculated the clearances on all available models of the St. Jude Medical mitral valve. Clearances were computed from measurements of valve dimensions with use of an electronic caliper. In all cases the clearance in antianatomic orientation was at least 49.5% greater (mean 59%, range 49.5% to 77.5%) than in anatomic orientation.