[Echocardiographic criteria of asymmetrical hypertrophy of the ventricular septum without outflow tract obstruction (author's transl)].

Asymmetrical septal hypertrophy (ASH) without outflow tract obstruction is a genetic variant of idiopathic hypertrophic subaortic stenosis (IHSS). Without difficulty and risk echocardiography can distinguish both diseases. Comparison in 33 patients with ASH but no outflow tract obstruction and in 29 with IHSS revealed following identical findings: (1) excessive hypertrophy of the ventricular septum when compared with the posterior wall of the left ventricle (asymmetrical septal hypertrophy); (2) decreased systolic motion of the septum; (3) slowed early diastolic closure of the anterior mitral leaflet; (4) relatively small end-diastolic and systolic diameter of the left ventricle. But the important distinction was that, while in IHSS there was a systolic forward movement of the anterior or both mitral leaflets, this not recorded in patients with ASH without outflow tract obstruction. The posterobasal portion of the left ventricle is thickened in patients with IHSS, due to the outflow tract obstruction.