Related Experiment Videos
Motion of mitral apparatus in hypertrophic cardiomyopathy with obstruction
Insights
In hypertrophic cardiomyopathy with obstruction, the mitral apparatus moves abnormally during systole. Obstruction results from the mitral anterior cusp contacting the posterior papillary muscle, not the septum.
Area of Science:
- Cardiology
- Medical Imaging
- Echocardiography
Background:
- Hypertrophic cardiomyopathy (HCM) can cause left ventricular outflow tract (LVOT) obstruction.
- The exact mechanism of LVOT obstruction in HCM, particularly the role of mitral valve motion, requires further elucidation.
Purpose of the Study:
- To investigate the dynamic motion of the mitral apparatus in patients with obstructive hypertrophic cardiomyopathy.
- To clarify the echocardiographic findings associated with systolic anterior motion (SAM) of the mitral valve.
Main Methods:
- Utilized conventional single-dimensional and multidimensional echocardiography.
- Analyzed systolic motion patterns of the mitral valve leaflets and papillary muscles.
Main Results:
- Observed anterosuperior displacement of the posterior papillary muscle during systole.
- Demonstrated anterior motion of mitral leaflets, with impingement of the anterior leaflet on the posterior papillary muscle.
- Identified the abnormal single-dimensional mitral echogram as a complex echo from chordae tendineae, papillary muscle, and anterior mitral leaflet.
Conclusions:
- Systolic anterior motion of the mitral anterior leaflet is less extensive than previously thought.
- LVOT obstruction in HCM is caused by systolic contact between the mitral anterior cusp and the posterior papillary muscle.
- Posterior papillary muscle displacement leads to chordal slackening, contributing to mitral leaflet SAM during ventricular ejection.
Abstract:
Motion of the mitral apparatus in hypertrophic cardiomyopathy with obstruction was investigated by conventional single dimensional and multidimensional echocardiography. In systole, anterosuperior displacement of the posterior papillary muscle, failure of mitral valve closure, and anterior motion of both mitral leaflets were shown. The anterior leaflet was seen to impinge on the posterior papillary muscle but not on the interventricular septum in systole. The abnormality of the single dimensional mitral echogram, previously ascribed to systolic anterior motion of the mitral anterior leaflet, was found to be a complex of echoes from the chordae tendineae, the papillary muscle, and, furthest from the septum, the mitral anterior leaflet. It is concluded that systolic anterior motion of the mitral anterior leaflet is of smaller amplitude than others have suggested, and that obstruction to left ventricular outflow in hypertrophic cardiomyopathy is produced by systolic contact between the mitral anterior cusp and the posterior papillary muscle. The theory is put forward that displacement of the posterior papillary muscle above and in front of the mitral leaflets produces chordal slackening, and that it is displacement of the chordae tendineae by the blood flowing to the aortic root during left ventricular ejection, which is responsible for systolic anterior motion of the mitral leaflets.