A study of the junction between glutaraldehyde-treated allogeneic aorta and host aorta.
OBJECTIVE
Stentless aortic valve bioprostheses have become popular because of their superior hemodynamics and expected increased durability. However, the stentless bioprosthesis differs from stented valves in that glutaraldehyde (GA)-treated tissue is implanted in direct contact with the native aorta. The effect of GA-treated tissue on host tissue has not been reported.


METHODS
In order to analyze the effect of GA in the healing process, sheep descending aortic conduits treated with 0.625% GA were inserted in the descending thoracic aorta of 10 adult sheep. The implants were removed after 4, 5, 10, 12, 15, 25, 30, 32, 60 and 120 days. The upstream and downstream junctions were evaluated macro- and microscopically, and by immunohistology for smooth muscle cell alpha-actin and von Willebrand factor.


RESULTS
By day 60 of implantation, the GA-treated conduits were calcified. By days 60 and 120, the calcification had spread to the host aorta, and was seen as foci of calcification in the junctional area. Acellular areas were also seen in the host aorta near the anastomosis. A fibrotic layer spanning the abluminal aspect of the junction between the implant and host aorta was present at day 4 and continued through 120 days. This layer was characterized by a progressive increase in collagenous matrix and cellularity, as well as new blood vessel formation. The luminal aspect of the junction had a neointimal layer of variable thickness containing alpha-actin-expressing cells covered by a monolayer of von Willebrand factor-expressing cells, seen at 15-30 days and present through 120 days.


CONCLUSIONS
In our model, implanting GA-fixed tissue in direct contact with living tissues resulted in cell death and calcification of host tissue within 60 days. The integrity of the junction did not appear to be compromised. This may be of interest in light of the increased popularity of the stentless aortic bioprosthesis.
Grobe
A C
AC
The International Heart Institute of Montana Foundation at St. Patrick Hospital and The University of Montana, Missoula 59802, USA.
Cheung
D T
DT
Luo
H H
HH
Shomura
Y
Y
Marchion
D C
DC
Pfau
J C
JC
Duran
C M
CM
D000199:Actins / Q000032:analysis; D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology*; D001021:Aortic Valve / Q000473:pathology*; D001705:Bioprosthesis; D002114:Calcinosis / Q000473:pathology*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D012756:Sheep; D015607:Stents; D013997:Time Factors; D014184:Transplantation, Homologous / Q000473:pathology; D014841:von Willebrand Factor / Q000032:analysis
D000199:Actins; D014841:von Willebrand Factor