How Is HCM Diagnosed?
HCM is usually identified by an echocardiogram that produces ultrasound images of the thickened wall of the heart muscle (hypertrophy of the left ventricle). This is usually most prominent in the ventricular septum (the wall separating the left and right ventricles), but is not accompanied by an enlarged cavity. Normal thickness of the left ventricle is 12 mm or less; in HCM, the thickness is usually 15 mm or more, although we know that some people who carry a mutant HCM gene may have normal wall thickness. In HCM patients, hypertrophy does not usually appear on echocardiogram until early adolescence and then may increase dramatically until the end of the accelerated growth period. However, since hypertrophy may not begin until middle age, we now suggest that some relatives of those with diagnosed HCM should be checked with an echocardiogram periodically well past adolescence. Small differences in wall thickness reported to adult patients from one clinic visit to another are usually no
