Echocardiographic and morphologic examination of left ventricular false tendons in human and animal hearts

False tendons are thin, fibrous or fibromuscular structures that traverse the cavity of the left ventricle with no connection to the valvular cusps; they may be single or multiple. We retrospectively analyzed echocardiograms for the prevalence of false tendons in the hearts of 368 (231 male, 137 female) newborns, infants, and children (mean age = 6.28 +/- 4.32 years) who were referred for echocardiography because of suspected acquired or congenital heart disease, but in whom no cardiac pathology was found. In addition, we studied the prevalence of false tendons in 90 hearts from three species of animals (dog, sheep, goat) and eight cadaveric human hearts. In our echocardiographic study, false tendons were detected in 97 of 368 hearts (26.4%). In our gross morphologic studies, false tendons were observed in most of the animal and human hearts: they were present in 5 of 8 (62.5%) human hearts, 14 of 20 (70%) dog hearts, 41 of 50 (82%) sheep hearts, and 16 of 20 (80%) goat hearts. The overall prevalence in animal hearts was 71 of 90 (78.8%). Histologic examination showed the false tendons to be composed of cardiac muscle, blood vessels, fibrous tissue, and Purkinje cells. The possible role of false tendons in innocent murmurs, cardiac rhythm disorders, or left ventricular dysfunction is discussed.