In vivo echocardiographic detection of cardiovascular lesions in apolipoprotein E-knockout mice using a novel high-frequency high-speed echocardiography technique.
Apolipoprotein E-knockout (apoE-KO) mice have been used for studying atherogenesis, but the in vivo features including cardiovascular function have not yet been reported. This study aimed to noninvasively evaluate cardiovascular lesions in 6 apoE-KO mice and 6 control (C57BL/6) mice using transthoracic echocardiography performed using an originally developed linear scanner that permits a high-speed scan with wideband high-frequency ultrasound. Two independent observers evaluated and scored the degree of atherosclerotic changes in the aortic root from 2-dimensional long-axis and short-axis images. M-mode measurements included left ventricular end-diastolic dimension (LVDd), posterior wall thickness (LVPWT), fractional shortening, aortic root dimension and rate of systolic expansion of the aorta (%SEAo). The wall thickness of the aortic root was measured from the serial histological sections. Significant differences between apoE-KO and C57BL/6 mice were found in the atherosclerotic score, %SEAo, LVDd and LVPWT. The atherosclerotic score and %SEAo were significantly correlated with the aortic wall thickness. Transthoracic echocardiography with a high-frequency ultrasound system can detect atherosclerotic lesions and the decreased distensibility of the ascending aorta, as well as secondary changes in left ventricular geometry, in apoE-KO mice.