Hypertrophic cardiomyopathy echocardiography

Editors-In-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org]

Overview
Echocardiography is the imaging modality of choice in the diagnosis of hypertrophic cardiomyopathy. Classically there is a small left ventricular cavity with hypertrophy out of proportion to any underlying condition that would cause LVH. The hypertrophy is often asymmetric.

Frequency of Hypertrophy
While LVH is usually present, not all carriers with HCM demonstrate left ventricular hypertrophy. Left ventricular hypertrophy may be absent in childhood. It may then appear following the rapid growth of adolescence and may first appear at age 17 to 18  .LVH may be time dependent and may appear late, particularly in patients with a mutation in the myosin-binding protein C gene. Patients generally present later in life and in general, have a better prognosis than beta myosin heavy chain or cardiac troponin T mutations. Up to 60% of patients at age 50 years have no evidence of LVH. LVH may appear later in life in these patients. Because of this, a normal EKG and a normal ECHO at maturity does not exclude the presence of an HCM mutation.

Diagnostic Features of Hypertrophy

 * Left ventricular hypertrophy (LVH) most often in an asymmetric distribution,
 * Thickening of the left ventricular wall in the absence of cavitary dilation and the presence of hyperdynamic activity (in fact there may be systolic cavity obliteration or near obliteration)
 * Absence of any other cause of left ventricular hypertrophy such as aortic stenosis or hypertension

Left Ventricular Wall Thickness

 * The traditional definition requires a wall thickness > 15 mm.
 * Borderline wall thicknesses of 13-14 mm must be distinguished from extreme variants of athletes heart
 * There are some genetic variants that yield a normal wall thickness.
 * Among children < 13 years of age, LVH is often absent.