Vevo 2100 high resolution system

Transthoracic echocardiography was performed using an echocardiograph (Vevo 2100 high-resolution system, VisualSonics) equipped with a 40-MHz linear MS-550D transducer, under steady-state isoflurane gas anaesthesia in 0.8 L/min 100% O₂. The thickness of the left ventricular (LV) anterior and posterior walls was measured in the short axis using 2-dimensional-guided (2D) M-mode echocardiography over the entire cardiac cycle. The LV volumes, fractional shortening (FS %), ejection fraction (EF %), and the corrected LV mass were calculated with the Vevo LAB cardiac package software using the following equations: LV vol diastole (d) = (7.0/[2.4 + LVIDd]) × LVIDd³, LV vol systole (s) = (7.0/[2.4 + LVIDs]) × LVIDs³, FS % = 100 × ([LVIDd – LVIDs]/LVIDd), EF % = 100 × ([LV vol d – LV vol s]/LV vol d), and corrected LV mass = 0.8 × 1.053 × ([LVIDd + LVPWd + IVSd]³ – LVIDd³), where ID is the internal diameter, PW is posterior wall thickness, and IVS is the interventricular septum thickness.

Transthoracic echocardiography was performed on anesthetized mice (1–3% isoflurane and 1 Lpm oxygenated room air) by using a Vevo 2100 high-resolution system (Visualsonics, Toronto, ON, Canada) and a 40-MHz MS-550D transducer. Two-dimensional B-mode tracings were recorded in both parasternal long and short axis views at the level of the papillary muscles and the pulmonary artery (PA), respectively, followed by one-dimensional M-mode tracings in both axes at the papillary level or pulsed-wave (PW) Doppler measurement of the peak flow in the PA. The right ventricle was recorded in B- and M-mode in a modified parasternal long axis view with an adjusted angle focussing the RV. Data were analysed offline using VevoLab 3.2.6 and the integrated cardiac measurement package. Ventricular wall thickness at end-diastole was used to characterize RV and LV microanatomy while the change of right- or left-ventricular diameter length, respectively, from end-diastole to end-systole was used to judge contractility and calculate RV or LV fractional shortening (FS). Pulmonary artery hypertension was correlated as previously described utilizing the ratio of pulmonary artery acceleration over ejection time in the PW diagram [19 (link)]. Cardiac output was monitored using the integral of PA flow, PA diameter, and heart rate. Three consecutive cardiac cycles were used for every analysis.