Echocardiography Protocol for Small Animal Models

Echocardiography was performed as previously described [34 (link)]. Briefly, transthoracic echocardiography was performed using a high-resolution echo machine with a 30 MHz probe. Animals were anesthetized with 3% isoflurane, their chests were shaved, and temperature-controlled anesthesia was maintained with 1.5% isoflurane. The probe was situated perpendicular to the heart to determine the position, and then, the probe was rotated clockwise 30-45 degrees to determine the left ventricle of the heart. The following parameters were measured from the M-mode images and two-dimensional images obtained in the short-axis views by the corresponding matching software (Vevo 2100 high-resolution small animal ultrasound system, VisualSonics, Canada): the percentage of fractional shortening (FS, %), ejection fraction (EF, %), left ventricular end-diastolic volume (LVEDV), and left ventricular end-systolic volume (LVESV). Stroke volume (SV) was calculated using the formula: LVEDV − LVESV (Figure S1).