Objective: To compare the results of echocardiographic evaluation of pressure overload-induced cardiac remodeling in mice using different ultrasound machines.
Methods: Eighteen C57 BL/6 mice were randomly divided into the sham-operated and the transverse aortic constriction (TAC) groups (n=9). Eight weeks after the operation, the cardiac function of TAC group was evaluated using Siemens ultrasonic instrument with 15L8 probe and the differences between the awake and anesthetized states were compared. The heart rate, left ventricular (LV) dimensions, systolic and diastolic functions were measured in both sham-operated and TAC groups using the Siemens ultrasonic instrument and a high-resolution ultrasonic imaging system for small animals (Vevo 770).
Results: Compared with the mice in wakefulness, the anesthetized mice showed significantly decreased heart rate and LV fractional shortening (P<0.001) and markedly increased LV end diastolic diameter and LV end systolic diameter (P<0.05). Both machines sensitively detected the cardiac remodeling of TAC mice in comparison with the sham-operated group. Compared with Siemens machine, Vevo 770 provided a higher resolution of 2D and M mode echocardiography with clearer Doppler frequency image of the mitral valve flow for evaluation of the LV diastolic function.
Conclusion: Both machines are suitable for evaluating cardiac remodeling induced by pressure overload independent of anesthesia, though anesthesia depresses cardiac function. Vevo 770 is optimal to evaluate LV diastolic function in mice.