The pathology of wear in the Beall model 104 heart valve prosthesis.

Abstract

We examined 13 Beall model 104 prostheses recovered at surgery or autopsy 10 to 84 1/2 months after insertion and observed the pattern of prosthesis wear. We defined wear as "mild" when the disc was notched but neither the metal of the struts was exposed not the cloth seat torn. In "moderate" wear the disc was notched, the Teflon coating of the struts was worn away exposing the underlying metal but the cloth of the set was not torn. The cloth seat was torn in "severe" wear, exposing the metal seat and causing a different pattern of disc erosion. In one case this allowed the disc to tilt into the valve lumen and, later, to escape from its cage. Most of the prostheses studied showed "moderate" or "severe" wear. We believe that some degree of wear is inevitable. Clinical signs and symptoms were not specific but a rough correlation existed between the severity of hemolysis, as indicated by serum LDH levels, and the degree of prosthesis wear. When wear was "severe", the results of cardiac catheterization studies usually mirrored the change, but there were a few exceptions. All patients with the Beall model 104 prosthesis may eventually develop "severe" wear, and we recommend regular reassessment with a view toward prosthesis replacement.