Objective:To evaluate the degree of pressure overload and successful ligation of transverse aortic constriction (TAC) using ultrasonic Doppler methods and investigate whether different gradient TAC made any differences in cardiac structure and function. Methods:A total of 60 male C57/BL6 mice were randomly divided into the sham－operated group (sham,n = 20)the 26 G needle banded TAC group (TAC26G,n = 20) and the 27 G needle banded TAC group (TAC27G,n = 20). The degree of pressure overload and successful ligation of TAC were determined by measuring the flow ratio defined by the right carotid arteries (RCA)/left carotid arteries (LCA). The effect of pressure overload on cardiac structure and function due to different gradient TAC were measured by calculating the heart weight/body weight (HW/BW) and left vetricle weight/tibia length(LVW/TL) and echocardiography. Results:Doppler assays showed that the RCA/LCA was significantly increased in both TAC26G and TAC27G compared with sham (P < 0.05). The ratio of RCA/LCA in TAC27G was significantly different from TAC26G (P < 0.05). Two weeks after the operation,compared with sham,IVSd and LVPWd were significantly increased in both the TAC26G and TAC27G group (P < 0.05);EF and FS were significantly increased in the TAC26G group but significantly decreased in the TAC27G group (P < 0.05). Two weeks after the surgery,the HW/BW and LVW/TL were significantly increased in both TAC26G and TAC27G compared with sham (P < 0.05),and the above index were much higher in the TAC27G group than the TAC26G group (P < 0.05). Conclusion:Our data revealed the relationship between carotid velocity change and cardiac hypertrophy in early the phase of transverse aortic constriction. It provided guidance on a better mouse model for pressure overload induced cardiac hypertrophy and heart failure.