An echocardiographic study of localized subaortic hypertrophy

A prospective echocardiographic investigation was undertakento determine the prevalence and significance of localized subaortichypertrophy in WOO consecutive patients presenting for a routineechocardiographic examination. Localized septal hypertrophywas diagnosed when the subaortic septum was hypertrophied (2 SD from normal)with a normal size cavity due to aortic valve disease (2 patientswere also hypertensive). Of the 180 patients with aortic valvedisease, localized subaortic hypertrophy was found in 10% ofthose with left ventricular hypertrophy and 33% of those withasymmetrical-septal hypertrophy (septum to posterior wall ratioof >l.5:1). There was no evidence of subaortic stenosis bypulsed and continuous wave doppler echocardiography (8 cases)and cardiac catheterization (6 cases). The aetiology of thisdiscrete localized muscular bulge is unclear but is presumablydue to change in shape of the septum with left ventricular hypertrophy.However, this finding has important implications as a causeof asymmetrical septal hypertrophy and because of the possiblefalse diagnosis of subvalvular stenosis and its effect on ultrasoundmeasurements.