Mechanics Analysis Of Aortic Dissection False Lumen: Animal Experiment

Background and Objective:Thoracic aortic dissection is the separation of medium layer of aorta, resulting from the inflow of the blood from the tear of the thoracic aorta. And the separation will expand along the longitudinal axis of the aorta. It is supposed that unlike abdominal aortic dissection, which rapture directly from the expanded aortic wall, the false lumen is first formed during the thoracic aortic dissection, and then rapture. We tried to testify this hypothesis with mechanics analysis of aortic dissection false lumen.Methods:1. Construct animal model.We opened the thoracic cavity and exposed the aorta. Find the interspace of the medium and widen with a self-made artery dilator. The balloon was put into the interspace of the medium and the medium was separated. With the mechanic dilation force and the soft impulse force of the liquid, the separation of the median was ever widened and the dissection was formed.2. Mechanics analysis of aortic dissection false lumen.We used microelectrical material parameter specified software to perform stretch test and record the yield index inside and outside of the false lumen.3.Methods for statistic analysisWe used t-test, SPSS 11, to analysis the data from the test.Results:1. Animal model Of 10 canine, one died from anesthesia and bleeding respectively, one die because of infection after operation, one failed to form aortic dissection. Six models were confirmed to form aortic dissection by radiology and anatomy.2. Results of mechanical analysis.u_max=(SE)/2 was tested by statistic analysis with significance (P< 0.05). Inner u_max >Outer u_max.Conclusions:1. During the formation of aortic dissection, the thoracic aortic wall was not ruptured but the false lumen was formed inside of the wall, which showed that the mechanical character was not consistent2. The mechanical analysis of the inside and outside space of the aortic medium layer showed that there was a mechanical difference between inner and outer space of false lumen.3. The mechanical difference of inner and outer layers of the aortic medium may be associate with smooth muscles which originate from different embryo layers.