Cineradiographic evaluation of the convexo-concave Björk-Shiley prosthetic valve in mitral position.

The in vivo function of the convexo-concave Björk-Shiley prosthetic valve implanted in mitral position was evaluated with a simple cineradiographic procedure. The maximum opening angle of the tilting disc, calculated from the maximum and the minimum diameter of the radiopaque marker embedded in the disc when viewed elliptically, was 56 +/- 2 degrees and was not affected by tachycardia up to 160 beats per min. The time required for disc opening was almost the same as that for disc closure, and these times shortened in proportion to increase in pulse rate. Disc rotation, quick or slow, could be observed in all patients. Excellent function of the convexo-concave Björk-Shiley prosthesis was demonstrated by cineradiography. Any dysfunction of the disc opening is easily demonstrable, not only from measurement of the disc's maximum opening angle, but also from evaluation of the distance, on en face view, between the characteristic internal rim disc marker and the small strut delineating the small valve orifice when the disc is fully open.