ABSTRACT
Objective:To observe the morphological and hemodynamics changes of aortic segments in mice with angiotensinogen Ⅱ(Ang II) combined with β-aminopropionitrile(BAPN) induced-aortic dissection by color Doppler ultrasound(CDUS).Methods:Twenty male mice of 6-8 weeks old C57BL/6 were randomly divided into two groups: the model group( n=10) was induced by intraperitoneal injection of Ang Ⅱ combined with BAPN to establish mice model with aortic dissection; the control group( n=10) was intraperitoneally injected with normal saline.The body weight, systolic and diastolic blood pressure of the mice were routinely recorded. On the 42th day, CDUS was used to measure the indexes of ascending aorta(AoA), descending thoracic aorta(DAo) and suprarenal aorta(SAo) in both groups, including the inner diameter of the cross section, peak systolic velocity(PSV), the end diastolic velocity(EDV), the resistance index(RI), the pulsatility index(PI), time average mean velocity(TAMV), the heart rate(HR) and the maximal shear rate(SR). Then, the aortas were harvested from the root to the bifurcation of the renal artery. The pathological changes of the aortic wall were observed using hematoxylin-eosin(HE) staining. Results:①There were statistically significant differences in body weight, systolic blood pressure, diastolic blood pressure and heart rate between the model group and the control group(all P<0.05). Compared with the control group(0/10), the incidence of the AoA dissection(8/10) in the model group was obviously higher, the difference was statistically significant( P<0.05); while the incidence of the DAo dissection(4/10) and the SAo dissection(3/10) in the model group was slightly higher, the differences were not statistically significant (all P>0.05). ②Compared with the ascending aorta of the control group, the inner diameter, PSV, EDV, TAMV, PI and SR in the model group were significantly higher(all P<0.05), while RI showed no significant difference between the two groups ( P>0.05). For the descending thoracic aorta, PSV, EDV, TAMV, PI and SR in model group were higher than those of the control group(all P<0.05), however the inner diameter and RI were not significantly different between the two groups (all P>0.05). And for the superior renal aorta, PSV, TAMV, RI, PI and SR in the model group were obviously higher than the control group(all P<0.05), whereas the inner diameter and EDV were not significantly different between the two groups (all P>0.05). ③The HE of the tissue section in the model group showed, the aortas were obviously dilated, irregular, with inhomogeneously thickening wall; the endothelial cell nuclei were slightly stained, and some intima and middle layer ruptured and protruded outward to form dissecting aneurysms. The adventitias were markedly infiltrated with inflammatory cells. Conclusions:Ultrasonography could primarily evaluate the hemodynamic changes of aorta in hypertension with aortic dissection, and the PSV, TAMV, PI and SR of aorta may be important indicators for early predicting the occurrence of aortic dissection in hypertension.