Remodeling Process Of Stanford B Thoracic Aortic Dissection Aneurysm After EVE: The Animal Study

Objective To establish the animal models of Stanford B thoracic aortic dissection with the canines of imitating human body's, and then perform endovascular exclusion with self-made SG(stent-graft); to determine the characteristics of biomechanics and histochemistry of the aneurismal wall and study correlation factors about aneurysm remodeling process after EVE. Methods 1.Using canine to be the studied object,"intima flap"double sides suturing method to establish Stanford B thoracic aortic dissection animal model, checking the shape of true and false cavity of aneurysm, and testing haemodynamics characteristics with duplex ultrasound; 2.Implanting self-made SG Through abdominal aortic artery, exclusing dissection entry, establishing Stanford B thoracic aortic dissection exclused animal model; 3. Follow-ups in different time points with CTA, determining dissection remodeling circumstance, including dissection shape, main entry and another reentrys, SG position, observeing its distortion,displacement,fall off and breakage; 4. Obtaining specimens in different time points through sentencing experiment animals, distinguishing to test biomechanics parameter of dissection vessel wall, obtaining curve and trend grasp of loading-displacement, straining-time, stress-time; 5. Obtaining specimens in different time points through sentencing experiment animals, distinguishing to detect immunohistochemistry, to obtain characteristics of elastic,collagen fibers,inflammation cell,vessel smooth muscle; Results 1. Having a good shape of Stanford B thoracic aortic dissection animal model, it is similar with the one of human body; 2. Checking blood flow speed and shape of dissection entry,true and false cavity, turbulence formation in entry, flow into true,false cavity, blood flow speed slow down, blood flow speed is similar in proximal area and distal dissection end; 3. Implanting self-made SG Through abdominal aortic artery, exclusing dissection entry totally, dissection aneurysm minification obviously, distal dissection aneurysm not exclused no change, no SG displacement,distortion,endoleak; 4. Following up in different time points, such as 1W,2W,4W,3M,6M,12M, with duplex ultrasound and CTA shows a lot of thrombus in exclused dissection ang distal dissection at 1W,2W,4W ; thrombus absorbed totally at 3M, the main entry is exclused completely in different time points, distal dissection reentrys are still patent, no thrombosis automatically; 5,Biomechanics testing results show the final shape-changed strength and the largest tensile strength of dissection vessel wall is at 4W after EVE, the secondary one is at 2W, the smallest one is at 1W, it is difficult to separate SG from dissection vessel wall for inlaying tight, accordingly it is impossible to test biomechanics. 6,Following up in different time points, such as 1W,2W,4W,3M,6M,12M, testing immunohistochemistry and the results show collagen and elastic fibers decrease, inflammation cell infiltrating at 1W, it is difficult to separate SG from dissection vessel wall for inlaying tight at 3M; Scanning electron microscope results show initial immature endothelial cell coverage in inner wall of SG is about at 6M, mature endothelial cell coverage completely is at 12M. Conclusion 1. Stanford B thoracic aortic dissection animal model established using"intima flap"double sides suturing method is similar to the one of human body, the model after EVE is suitable to study hemodynamics and perioperative treatment theory. 2. After EVE, the dissection vessel wall tensile strength is the smallest in acute stage (within 2W), getting bigger in chronic stage(over 2W), getting stable later. 3. There are the collagen and elastic fibers breakage in dissection vessel wall in different time points after EVE, accompany with inflamed reaction; endothelial coverage process of the SG is over after one year.