[Current therapeutic principles as well as new therapeutic aspects of idiopathic hypertrophic subaortic stenosis. II. Pathophysiology, natural course and diagnosis].

Idiopathic hypertrophic subaortic stenosis is a noncompensatory hypertrophy of the myocardium which above all concerns the ventricular septum in its upper part near to the basis. The etiology is not yet sufficiently clarified, though a genetic component is regarded as ascertained on account of the proved familial accumulations. Haemodynamically the morphologic changes effect a systolic obstruction of the left-ventricular outflow, an insufficiency of the mitral valve and an aggravated diastolic filling of the left ventricle. Further pathophysiological symptoms of the functional subaortic stenosis are an extremely rapid ejection of blood in the early, not obstructive phase of the systole as well as a pathological forward movement of the mitral valve beginning in the midst of the systole. The disease has a bad prognosis. To be sure, the natural course is usually characterized only by a slow progression of the complaints, however, particularly in adolescents frequently sudden cases of death appear by disturbances of the cardiac rhythm or a relative coronary insufficiency. The disease which is already frequently to be diagnosed according to anamnesis, auscultation, ECG and form of the pulse curve may be ascertained using the ultrasound echocardiography as well as heart catheterization including angiography. Apart from a direct measurement of the ventriculo-ventricular pressure gradient during wuch examinations the size of the functional obstruction may further be characterized by certain pharmaca or physical methods which influence the volume of the ventricle or the afterload.