Gender-dependent differences in echocardiographic characteristics of murine hearts

Gender-dependent differences in echocardiographic characteristics of the heart have been thought to exist in human subjects, but comparisons have been difficult because of potential confounders such as differential prevalence of occult disease. Little data are available characterizing echocardiographic descriptors in normal experimental animals despite wide use of this modality. Accordingly, we characterized systolic and diastolic criteria of cardiac function echocardiographically in C57BL6 and BalbC age-matched mice to determine whether results in males and females differed. Left ventricular dimensions in absolute terms were lower, transmitral valve A-waves smaller and isovolumic relaxation time greater in females. When dimensional data were normalized for body weight, differences persisted but were directionally opposite. Thus, detection of abnormalities in cardiac function echocardiographically in various strains of mice requires establishing reference values that are gender as well as strain specific. Furthermore, the results suggest that gender-dependent differences are likely to be present in other species, including humans, and accordingly, that normal values should be established separately for males and females.