[The meaning of the systolic progression of the mitral valve for the outflow tract obstruction in hypertrophic obstructive cardiomyopathy (HOCM). Studies by means of a valve model].

We constructed two valve models in order to investigate the cause of SAM of the mitral valve and the cause of the outflow tract obstruction in HOCM. With model 1 we were able to demonstrate that a subvalvular obstruction created a SAM of the mitral valve, there was also a pressure gradient distal to the obstruction, the valve itself did not create any obstruction. With model 2 we demonstrated that three causes were responsible for an outflow tract obstruction: 1. A narrow outflow tract even after removal of the mitral valve. 2. A position of the mitral valve close to a protruding septum and relatively short chordae tendineae. 3. A SAM of the mitral valve with apposition to the septum due to a Venturi effect. We were able to create a typical bisferiens poststenotic pressure curve in presence of a monophasic prestenotic curve. We conclude from our investigation that for the SAM of the mitral valve as well as for the outflow tract obstruction different anatomic structures may be responsible, which cause simular hemodynamic abnormalities. These abnormalities are most prominent in HOCM but not necessarily linked with this disease.