[Analysis of intrasac pressure after the implantation of endoprotheses with different diameters, in an animal model of abdominal aortic aneurysm].
OBJECTIVE
The effect of a plain 48-wire self-expanding flexible stent (Wallgraft Boston Scientific) on abdominal aortic aneurysms has been studied in a new animal model. We performed this study in order to analyze the mechanical properties of a bare-metal Wallgraft endoprostheses to investigate their responses to hemodynamic forces.


METHODS
Aneurysms were created by interposing fusiform segments of PTFE into the infrarenal aortas of 12 Large White pigs. The pigs were assessed after 2 weeks by telemetry pressure, ultrasonography and arteriography methods. Endovascular placement of the stents, 2 weeks after aneurysm creation, was performed under arteriographic control in the half of pigs (second group of study). These pigs were assessed by telemetry pressure, ultrasonography and arteriography methods, weekly after stenting; they were then sacrificed for pathological examination.


RESULTS
At 6 weeks the aneurysms in the first group were pulsatile with partial endothelialisation and no mural thrombus. Placement of the stent of different sizes in the second group was easily accomplished. Stenting resulted in an immediate reduction in wall pulsatility of all aneurysms and thrombosis of the excluded aneurysm sac occurred in three cases. In the other three cases the pulse pressure in the sac was reduced. In all cases there was a significant reduction in the maximum aneurysm diameter when measured weekly after stenting.


CONCLUSIONS
A pulsatile, non-thrombogenic aortic aneurysm model approaching human dimensions has been successfully developed for the study of endoprostheses prior to their clinical use. Endovascular placement of a plain, multiple-wire Wallgraft was associated with reductions in aneurysm pulsatility, pulse pressure within the sac and maximum aneurysm diameter over the study period. Stenting was associated with thrombosis of the excluded aneurysm sac in 50% of the cases.
Vaquero
Carlos
C
Laboratório de Investigação Cirúrgica e de Técnicas Experimentais, Unidade de Investigação em Angiologia, Faculdade de Medicina, Departamento Universitário de Histología e Biología Celular da Faculdade de Medicina de Valladolid e Instituto Cardiovascular de Santacruz de Tenerife, Canarias.
Arce
Nuria
N
Diago
Maria Victoria
MV
Grajal
Carmen
C
Agudo
Javier
J
Martinez
Rafael
R
D000818:Animals; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology* / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D006439:Hemodynamics; D013552:Swine