Effect Of Hemodynamics On Pathogenesis Of Abdominal Aortic Aneurysms

Procedue and MethodThe main factors of haemodynamics in this reserch are arterial pressure, wall circumferential tension, wall circumferential stress, blood flow and shear stress. The effect of these factors on pathogenesis of abdominal aortic aneurysms was dynamically and systemically observed and studied to discover more pathogenesis of abdominal aortic aneurysms and establish the theoretical basis for the tratment.â… . To construct an animal abdominal aortic aneurysm modelThe bovine jugular vein segments were removed to hybrid canines at infra-kidney abdominal aortic to construct aneurysms.â…¡. Arterial pressureThe arterial pressures were recorded endoluminally and compared at thoracic, suprarenal, infrarenal aorta, common iliac artery and entrance, body, exit of aneurysms in canines and persons, model and patients. The arterial pressure waves in different diameter aneurysms were recorded and compared.â…¢. Wall circumferential tension and stressWe studied canines, models, person and patients. The systolic, diastolic and mean blood pressure were recorded endoluminally at thoracic, suprarenal, infrarenal aorta, common iliac artery, and entrance, body, exit of aneurysms. The radius of vessel and the thickness of vascular wall were measured. The wall circumferential tension and stress were calculated.â…£. Blood FlowThe blood streams in abdominal aortic aneurysms with different diameter were measured by Doppler ultrasound. The blood streams in different areas and points of abdominal aortic aneurysms were measured by Doppler ultrasound, and the speed waves were recorded.V. Shear StressThe blood streams in the different points, which were at different intervals to the arterial wall and in five planes (entrance, proximal section, central section, distal section and exit of the aneurysm), were measured by Doppler ultrasound, and the speed waves wererecorded. The shear stress was calculated by hydrodynamic theory.VI. Haemodynamic Change after Endovascular Exclusion of AA AAneurysm exclusion was performed in AAA patients. Following stent-graft implantation,pressure measurements were performed through a catheter adjacent to the graft in the aneurysm. The diameter of aneurysms, the thick of walls, and the blood flow in aneurysms were measured by ultrosound. The wall circumferential tension, stress and shear stress were calculated.Result and Conclusion1. This model can be applicated in hemodynamic study of abdominal aortic aneurysm.2. The increased systolic and mean pressure may be one cause to make infrenal aorta damageable and be prone to form aneurysms. The big pressure in AAA would accelerate the development and rupture of aneurysms. The pressure wave in abdominal aortic aneurysm was changing and F wave became bigger during the growth of the abdominal aortic aneurysm. That may increase the burthen of the aneurysms' wall and accelerate the aneurysm to expand and rupture.3. The wall tension of aneurysms was increased while the radius increasing. It would accelerate the development of aneurysms. In healthy canines and healthy person, the wall stress was biggest at infrarenal aorta. And the wall stress of aneurysms was increased while the radius increasing. The wall stress was biggest at body and exit of aneurysms. Common iliac artery's wall stress was decreased, but even bigger than thoracic, suprarenal aorta and entrance of aneurysms. It could explain why the infrenal aorta was prone to form aneurysm and the aneurysm tended to invade distant and common iliac artery. The big wall circumferential tension and stress were important factors in origination and develepment of AAA.4. The blood streams are different in different areas of abdominal aortic aneurysm and in...