A Comparative Study Of Constructive Method Of Aortic Arch Dissection Animal Model And Similarity With Human Dissection

Objective:Comparing the effectiveness and safety of different methods for constructing an aortic arch dissection animal model,explore the best method for constructing an aortic arch dissection（AAD）animal model.Compare the similarity of hemodynamic parameters between AAD animal model and real-world human AAD,and evaluate the feasibility of this animal model as an experimental platform for studying human AAD.Methods:（1）A total of 24 local healthy mongrel dogs,24-30 months old and weighing 20-26Kg,were selected and randomly included in the experimental group（A）and the control group（B,C,D）,with 6 dogs in each group.Group A uses the"transvenous incision needle high-pressure water flow impact modeling method"to build the AAD model,group B uses the"transvenous incision needle non-high pressure water jet impact modeling method",and group C uses the"transarterial sheath non-high pressure water flow impact modeling method"and group D used the“two-way balloon dilation combined with elastase perfusion modeling method”to construct the AAD model.Imaging examination was performed immediately after operation and 7 days after operation to observe the formation of AAD.The experimental dogs were sacrificed at the experimental node（15 days after surgery）,and the aortic tissue was removed to visually observe the formation of AAD（if the experimental dog died during the operation or before the experimental node,the specimen was dissected and the cause of death was immediately dissected）.Three different staining methods of Masson,Movat and EVG were used to detect the histopathology of the dissection.Collect four groups of models,compare and analyze the success rate of model construction,the length of interlayer tear,postoperative survival rate,survival time,etc.,and compare the effectiveness and safety of different methods to build AAD animal models.（2）CT scans were used to obtain aortic dissection images of real world human AAD patient（model A）and experimental dogs（model B）,and DICOM data was imported into Mimics medical image processing software.Set the corresponding gray threshold interval,and extract image data of blood vessel tissue through automatic threshold segmentation and manual separation.Using the industrial software GEOMAGICS to perform surface fitting and smoothing on the data exported by Mimics,a computer-aided design three-dimensional model for numerical calculation is finally formed.The computational fluid dynamics software was used to simulate the blood flow in the aortic cavity,and the blood flow field in the true and false cavity of the aortic dissection was numerically analyzed to obtain the relevant hemodynamic parameters.Analyze and compare the blood vessel wall pressure,blood flow field streamline distribution and wall shear stress of the two at different times of the cardiac cycle（T₁:Acceleration period of contraction 0.04 s,T₂:peak period of contraction 0.08 s,T₃:period of contraction and deceleration 0.14 s,T₄:diastolic period 0.40 s）to evaluate the dog AD model.Results:1、There was no statistical difference between the four groups in gender,age,weight and other general conditions（P>0.05）.2、The success rates of the four groups of experimental dogs AAD model construction were 83.3%（5/6）,83.3%（5/6）,66.7%（4/6）,16.7%（1/6）,and the success rate of model construction between the four groups were significant statistical differences（P<0.01）;among them,the model building success rate of group A was significantly higher than that of group D（P<0.05）;the model building success rate of group A was not statistically different from that of groups B and C（P>0.05）.3、The dissection tear lengths of the four groups of experimental dog AAD models were 14.4±3.0,11.3±4.2,7.0±2.3,and 4.7±0.6 cm,respectively.There were statistical differences in the interlayer tear lengths between the four groups（P<0.05）;The tearing length was significantly longer than that in groups C and D（P<0.05）;the tearing length of group A was not statistically different from that in group B（P>0.05）.4、The average postoperative survival time of the four groups of experimental dogs was 13.0±4.0,6.4±4.3,3.3±1.5,and 9.3±5.8 days respectively.There was a statistical difference in the average postoperative survival time between the four groups（P<0.05）;Among them,the average postoperative survival time of group A was significantly higher than that of groups B and C（P<0.05）;the average postoperative survival time of group A was not statistically different from that of group D（P>0.05）;There was no statistically significant difference in post-survival rate（P>0.05）.5、The pathological staining results showed that the elastic fibers at the AD tear were destroyed,and the lamella separation occurred.The elastic fibers on the outer wall of the false cavity were over-stretched and distributed linearly,while the elastic fibers on the inner wall were still arranged in a wave shape.The staining results are consistent with the pathological changes of AD.6、CFD results show that the pressure in the AAD false cavity is higher than that in the true cavity,the most obvious in T2;the wall shear stress at the entrance of the false cavity is significantly higher than other parts,and increases with the increase of the inlet blood flow velocity;The blood flow in the AD true cavity is more stable than that in the false cavity,and the false cavity is prone to blood turbulence and reflux in T3 and T4.7、Experimental dog AAD model and real-world human AAD at different moments of cardiac cycle,the hemodynamic parameters such as the pressure distribution of the vessel wall,the shear stress distribution on the wall surface and the streamline of the velocity field are similar.Conclusion:1、Transvenous incision needle high-pressure water flow impact modeling method（group A）is easy to operate,the intraoperative aortic occlusion time is short,the dissection is wide in scope,the average postoperative survival time is long,the water flow impact process and human hypertension fluctuate Similar,can be used as the preferred method of animal AAD model construction.2、The experimental dog AAD model established in this experiment is similar to hemodynamic parameters such as blood vessel wall pressure,wall shear stress and blood flow field streamline distribution of real-world human AAD,which can be used for subsequent basic research and improvement of intraluminal treatment technology.