Left ventricular false tendon

Epidemiology

The incidence of false tendons ranges from 18-26% during 2-dimensional echocardiographic analysis, to a reported 34% incidence at autopsy ^2,8. Prevalence is reported in a ratio of 0.4-61%. In low-risk pregnancies, they occur between 3 -5% ¹.

Clinical presentation

False tendons may leads to arrhythmias, such as intracavitary ventricular tachycardia or pre-excitation rhythms, as well as causing left ventricular hypertophy with resultant systolic dysfunction ^1,2,4.

According to the Framingham Heart Study, individuals with left ventricular false tendons are more likely to have lower body mass indexes, but this finding may be a reflection of the superior image quality obtained in such individuals ^3,4.

Pathology

Left ventricular false tendons are benign cardiac anatomic variants defined as single or multiple structures that traverse the left ventricle between interventricular septum and left ventricular free wall or papillary muscles with no connection to the valve leaflets ^1,2,4. The range of thickness of the bands range from 3 mm to <1 mm and their length is variable. They contain varying amounts of fibrous and myocardial tissue, as well as coronary vessels and Purkinje fibers ⁴, leading to their aforementioned clinical presentation ³.

Microscopic appearance

Reported microscopic examination showed false tendons to be composed of endocardium of up to 3 µm thickness with underlying myocardial tissue that has all the features of the myogenic conducting tissue ².

Radiographic features

Although numerous studies have demonstrated that left ventricular false tendons are found more frequently in autopsy than echocardiographically during life, they are still easily detectable by echocardiography where they are often noted incidentally ^4,7. The preoperative sensitivity and specificity of echocardiography were 82% and 85%, respectively ⁶. 

False tendons can be differentiated from other structures because of the presence of echo-free spaces on both sides of the tendon, and systolic laxity. In the case of a rupture of a false tendon, they must be distinguished from vegetations, thrombi, and ruptured chordae tendineae, because they can then produce intracavitary echoes ⁷.

The use of three-dimensional imaging in echocardiographic identification of left ventricular false tendons is still in its infancy, and its role remains to be established ⁴.

Treatment and prognosis

It has been reported that the presence of left ventricular false tendons on echocardiographic examination was not associated with the risk of mortality ³. However, the rupture of a false tendon may acutely result in congestive heart failure, depending on its size and location.