Heterograft Replacement of the Mitral Valve: Clinical, Hemodynamic, and Pathological Features
Seventeen patients had replacement of their diseased mitral valves with formalin-fixed, mounted porcine heterografts over a ten-month period with no operative or postoperative mortality.
Hemodynamic studies early after operation indicate that patients with heterograft mitral valves behave no differently than patients who have had replacement of the mitral valve with ball valves. The early postoperative myocardial dysfunction present after mitral valve replacement is probably not related to the presence of a caged ball or other such device in the left ventricle. Late hemodynamic studies in two patients have shown complete competence of the valves and minimal mean diastolic and absent end-diastolic gradients at rest between the left atrium and left ventricle.
Six of the valves became incompetent and were removed from 2 to 11 months after operation. Histological study of these valves suggests that the development of incompetence in five of them was related to absorption of muscle beneath the right coronary cusp with retraction of the tissues supporting this cusp and subsequent avulsion of the adjacent tissues from the supporting frame.
The 11 patients whose valves remain competent are all clinically improved 6 to 15 months after operation. There have been no thromboembolic complications in any of the patients although long-term anticoagulation has not been used.
The failure of the aortic valve heterografts mounted on rigid frames in this series appears related to mechanical stress resulting from imperfect coaptation of the valve cusps, either from resorption of heterograft tissue or improper mounting. Further studies are necessary to clarify these observations.
- © 1970 American Heart Association, Inc.