[Reconstruction of the common carotid artery with freeze  dried arterial allografts in goats].
OBJECTIVE
To observe the patency rate and histopathologic changes at different times after implantation of freeze dried arterial allografts.


METHODS
4 healthy adult goats were used as the experimental models. A segment of the common carotid artery 2 cm in length was surgically removed and bridged with freeze-dried graft of common carotid artery from another goat. The eight necks of 4 animals were divided into A and B group randomly, each containing 4 arteries. In group A, both cut ends of the carotid artery were anastomosed end to end with the arterial allograft. In group B, the proximal end of the carotid artery was anastomosed end to side with the allograft. The patency of the graft was monitored with Laser Doppler Flowmeter within one week and carotid angiography was performed in selected animal. The allografts with anastomoses were harvested at 1 week, 2 weeks, 3 months and 6 months after implantation, respectively. The surgical fresh specimens were prepared and subject to histopathologic evaluation under light microscope, scanning electron microscope and transmission electron microscope.


RESULTS
In Group A, 2 grafts were patent at 1 week and 2 weeks, respectively. One graft was not patent at 3 months, one was largely occluded at 6 months, only 1/4 part of the graft was patent. In Group B, 3 grafts were patent at 1 week, 2 weeks, 3 months, respectively. One graft was occluded at 6 months. There was no significant difference in patency rate between the two groups. Histopathologic examinations showed that in freezed dried arterial homograft, the endothelial cells were lost but the matrix was complete. One week after implantation, mononuclear macrophages were infiltrated into the wall in large amount and adventitia of loose connective tissues was formed. After 2 weeks of implantation, intimia was noted, intimal hyperplasia was also noted at the anastomotic sites and migrated toward the central portions of the graft. At 3 months, the homograft displayed a complete endothelial cell coverage with only small areas of fresh fibrin and endothelial disruption. The rejection reaction was diminished prominently. The medial matrix was largely substituted by proliferation of smooth muscle cells, the homograft was near normal in structure.


CONCLUSIONS
Reconstruction of carotid artery defect with freeze dried arterial homografts was feasible. The rejection reaction was not significant. If the endothelial lining does not regenerate within 3 months, long term graft patency is hardly achieved.
Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, School of Stomatology, Shanghai Second Medical University, Shanghai 200011, China. zhjw@citiz.net
J W
JW
Zheng
W L
WL
Qiu
Z Y
ZY
Zhang
G C
GC
Lin
H G
HG
Zhu