Structure-related thrombosis involving a porcine xenograft valve

A patient developed acute congestive heart failure following chordal rupture and underwent mitral valve replacement with a porcine xenograft. He recovered adequate hemodynamic function but died one month later with widespread bronchopneumonia. Postmortem examination revealed a prominent muscular shelf in the right coronary leaflet of the xenograft, and focal thrombosis involving the adjacent sewing ring and left atrial wall. The location of the thrombus suggests that it formed as a result of local stasis behind the large muscular shelf. Limiting the size of this muscular shelf by valve selection and construction may reduce the thrombogenicity of this prosthesis.