Comprehensive Echocardiographic Assessment of the Right Ventricle in Murine Models

Non-invasive high-resolution echocardiography to evaluate cardiovascular function of small animals is increasingly being used due to availability of genetically engineered murine models. Even though guidelines and standard values for humans were revised by the American Society of Echocardiography, evaluations on murine models are not performed according to any standard protocols. These limitations are preventing translation of preclinical evaluations to clinical meaningful conclusions. We have assessed the right heart of two commonly used murine models according to standard clinical guidelines, and provided the practical guide and sample values for cardiac assessments.

Right heart echocardiography evaluations of CD1 and C57BL/6 mice were performed under 1-3% isoflurane anesthesia using Vevo® 2100 Imaging System with a high-frequency (18-38 MHz) probe (VisualSonics MS400). We have provided a practical guide on how to image and assess the right heart of a mouse which is frequently used to evaluate development of right heart failure due to pulmonary hypertension.

Our results show significant differences between CD1 and C57BL/6 mice. Right ventricle structural assessment showed significantly larger (p < 0.05) size, and pulmonary artery diameter in CD1 mice (n = 11) compared to C57BL/6 mice (n = 15). Right heart systolic and diastolic functions were similar for both strains.

Our practical guide on how to image and assess the right heart of murine models provides the first comprehensive values which can be used for preclinical research studies using echocardiography. Additionally, our results indicate that there is a high variability between mouse species and experimental models should be carefully selected for cardiac evaluations.