Hemodynamics and aneurysm development in vascular allografts.
OBJECTIVE
Mechanical and immunologic factors may play a role in the development of native arterial and biologic graft aneurysms. We developed an experimental rat aortic allograft aneurysm model in which segments of infrarenal aorta were transplanted between hypertensive and normotensive rats to study these factors in this model.


METHODS
Aortic allografts and autografts were inserted into spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. Effects of immunologic and antihypertensive therapy were evaluated. Graft diameters were followed up with magnetic resonance imaging and at harvest. Direct-pressure measurements were taken and dp/dtmax (force of ventricular contractions) was calculated before harvest.


RESULTS
Autografts remained isodiametric and maintained their histologic architecture. Aneurysmal dilation of transplanted segments occurred in SHR host allografts but not in WKY host allografts. Histologic examination of all allograft specimens noted a rejection reaction characterized by inflammatory cell infiltration and medial smooth muscle cell loss. Antigenic enhancement accelerated aneurysm development in SHR hosts but had no significant effect on WKY hosts. Rates of allograft enlargement and final allograft diameters were similar in antihypertensive treated and untreated SHR hosts. The dp/dtmax in untreated SHR hosts was greatest and differed significantly from that in the WKY rats but only marginally from that in treated SHR hosts.


CONCLUSIONS
Immunologic rejection but not abnormal hemodynamics is necessary for development of allograft aneurysm in this model.
Petersen
M J
MJ
Department of Surgery, Massachusetts General Hospital, Boston 02114.
Abbott
W M
WM
H'Doubler
P B
PB
L'Italien
G J
GJ
Hoppel
B E
BE
Rosen
B R
BR
Fallon
J T
JT
Orkin
R W
RW
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use; D001012:Aorta, Abdominal / Q000637:transplantation*; D017544:Aortic Aneurysm, Abdominal / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D001794:Blood Pressure / Q000187:drug effects; D006082:Graft Enhancement, Immunologic; D006083:Graft Occlusion, Vascular / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D006084:Graft Rejection / Q000276:immunology*; D008297:Male; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000473:pathology; D011183:Postoperative Complications / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D016038:Skin Transplantation / Q000276:immunology
D000959:Antihypertensive Agents