Vevo 770 ultrasound

To analyse LV function and dimension, transthoracic two-dimensional echocardiography was performed in mice sedated with 5% isoflurane, using the Vevo 770 Ultrasound (Visualsonics), equipped with a 30-MHz linear array transducer. M-mode tracing were used to measure LV anterior and posterior wall thickness and LV internal diameter at end-systole and end-diastole in short axis view, which were used to calculate fractional shortening and ejection fraction.

Using a Vevo 770 ultrasound machine equipped with a 30 MHz transducer (Visualsonics, Toronto, Canada), in vivo cardiac function and morphology were assessed. Mice were anesthetized in an induction chamber using 2.5% isoflurane and then transferred to a heated ECG platform for heart rate monitoring during the imaging procedure. Standard B-mode (2D) and M-mode images were taken in the short axis position at the level of the papillary muscles for each animal. Data analysis was performed by an experienced imager using the Visualsonics Vevo 770 cardiac analysis package. 2  M-modes were analyzed per animal with an average being taken for each.

Transthoracic echocardiography was performed under isofluorane anaesthesia at week 18–19 (n = 5–6 per group) by a single operator blinded to the experimental status of the mice. Short axis views of the left ventricle (LV) were obtained at the mid papillary muscle level (Vevo 770 ultrasound, Visual Sonics, Canada) and fractional area change determined by manual tracing of the LV wall end diastolic and end systolic areas. Ventricular wall and cavity dimensions were assessed with M-mode measurements; ejection fraction was determined from these measurements by automated software (Visual Sonics). Pulse wave doppler at the aortic annulus was used to measure the velocity timed integral of aortic flow, which was multiplied by the LV outflow tract area to calculate stroke volume and cardiac output. Cardiac output was indexed to body weight for each mouse.
Histological analyses of LV morphology and cardiomyocyte size were performed on haematoxylin/eosin-stained 7 µm sections through the left ventricle 500 µm below the inferior edge of the mitral valve. Mean cardiomyocyte area and diameter were determined from measurements on 50 cells in transverse and longitudinal cross section respectively per mouse (image analysis software as above).