Morphologic and Histologic Evaluation of Left Ventricular False Tendons in Human, Cadaveric, and Swine Hearts: A Clinical Implication for Two-dimensional Echocardiographic Classification

Background: Left ventricular false tendons (LVFTs) are normal, benign anatomic cords in the left ventricle that usually extend from the ventricular septum to the base of the papillary muscle or the free wall of the left ventricle. Due to its clinical relevance, we aimed to classify the tendons using two-dimensional (2D) echocardiography, based on width measurements and histological findings from the tendons studied in cadaveric heart specimens. Materials and Methods: Morphology and prevalence were studied in 676 infants using 2D echocardiography, 68 specimens of congenital heart defects, 20 swine hearts, and 100 cadaver human hearts. The width of the tendons was measured using vernier callipers in cadaveric specimens. A histological study of 28 LVFT specimens was done and classified into three types. The same width measurements were applied in 2D echocardiography to derive a probable classification. Results: LVFTs were found in 538 (79.5%) of the 676 infants by 2D echocardiogram, of which 238 (44.4%), 249 (46%), and 51 (10%) were fibrous, fibromuscular, and muscular, respectively. 42 (61.8%) of the 68 congenital heart disease specimens, of which 23 (37%), 23 (37%), and 5 (12%) were fibrous, fibromuscular, and muscular, respectively. Nineteen (95.0%) of the 20 piglet hearts, in which 23 (69.7%) and 10 (30.3%) were fibrous and fibro-muscular, respectively, whereas none were muscular. Forty-nine (49%) in cadaveric hearts, in which (53) 91.4%, 4 (6.9%), and 1 (1.7%) were fibrous, fibromuscular, and muscular, respectively. Histological study of tendons in cadaveric showed 5 (62%), 2 (25%), and 1 (13%) and in congenital heart specimens were 7 (35%), 11 (55%), and 2 (10%) as fibrous, fibromuscular, and muscular, respectively. Conclusions: LVFT can be classified as fibrous, fibromuscular, and muscular types using the width measurements by 2D echocardiography based on the association between the width and histology studied from various specimens.