Behavior of mitral allografts in the tricuspid position in the growing sheep model.
BACKGROUND
On the basis of a previous experience in a chronic sheep model in which partial mitral allografts remained viable and properly functioning 12 months after operation, we assessed the results obtained by replacing the tricuspid valve with fresh antibiotic-preserved mitral allografts.


METHODS
Twenty 3-month-old sheep with a mean weight of 23.7 +/- 2.3 kg underwent cardiopulmonary bypass and had a fresh antibiotic-preserved mitral allograft implanted in the tricuspid position with the heart beating under normothermic conditions. The tricuspid valve apparatus was not excised. After a mean follow-up of 13.2 months, the allograft was evaluated by gross inspection and light and electron microscopy.


RESULTS
Nine sheep died of technical causes within the first week after operation and 2 at 4 and 6 months of infective endocarditis of the allograft. The hemodynamic study before heart explantation revealed residual tricuspid incompetence in 3 of the 9 survivors. Macroscopic examination showed flexible valves with no signs of structural deterioration, calcification, or thrombosis. Under light and scanning electron microscopic examination, allografts were almost completely denuded of endothelial cells and showed loosely arranged connective tissue with scarce signs of inflammatory reaction. Despite these findings, allografts were free from major structural damage.


CONCLUSIONS
The mitral homograft could be an alternative to replacement of the tricuspid valve with a bioprosthesis or a mechanical prosthesis.
Bernal
J M
JM
Department of Cardiovascular Surgery, Hospital Universitario Valdecilla, Universidad de Cantabria, Santander, Spain.
Rabasa
J M
JM
Cagigas
J C
JC
Val
F
F
Revuelta
J M
JM
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002114:Calcinosis / Q000473:pathology; D002315:Cardiopulmonary Bypass; D002423:Cause of Death; D003238:Connective Tissue / Q000473:pathology; D004195:Disease Models, Animal; D004697:Endocarditis, Bacterial / Q000209:etiology; D004730:Endothelium, Vascular / Q000473:pathology; D005500:Follow-Up Studies; D006085:Graft Survival; D006128:Growth; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics; D008855:Microscopy, Electron, Scanning; D008943:Mitral Valve / Q000473:pathology / Q000637:transplantation* / Q000648:ultrastructure; D009926:Organ Preservation; D012756:Sheep; D013530:Surgical Wound Infection / Q000209:etiology; D015996:Survival Rate; D013927:Thrombosis / Q000473:pathology; D014184:Transplantation, Homologous; D014261:Tricuspid Valve / Q000601:surgery*; D014262:Tricuspid Valve Insufficiency / Q000503:physiopathology / Q000601:surgery
D000900:Anti-Bacterial Agents