Left ventricular false tendon

Left ventricular false tendons, also known as left ventricular muscular bands, are fibromuscular structures that arise from the inner trabeculated myocardial layer of the left ventricle. They may have different lengths and thicknesses.

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%. 

Clinical presentation

False tendons may lead to arrhythmias, such as intracavitary ventricular tachycardia or pre-excitation rhythms, as well as causing left ventricular hypertrophy 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 the 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 fibres 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. 

Ultrasound imaging features of tendons include:

• in longer tendons, two separate myocardial insertions be visualized
• an anechoic space between tendon and adjacent endocardium (distinguishes from thrombus or vegetation) ⁷
• diastolic Doppler flow between tendon and adjacent endocardium ⁷
• a pattern of motion suggestive of systolic laxity

Ruptured false tendons may resemble vegetation, thrombus, or ruptured chordae tendineae;however, their chaotic motion, tissue texture, and site of attachment may help in diagnosis 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 an increased risk of mortality ³. However, the rupture of a false tendon may acutely result in congestive heart failure, depending on its size and location.