- Meeting abstract
- Open Access
2082 "Two-dimensional M-Mode" display of the mitral valve from CMR cine acquisitions: insights into normal leaflet and annular motion
© Chan et al; licensee BioMed Central Ltd. 2008
- Published: 22 October 2008
- Mitral Valve
- Cardiac Cycle
- Mitral Annulus
- Phase Duration
- Mitral Leaflet
CMR assessment of the mitral valve provides unique insights into its normal annular and leaflet motion. Although various other modalities have investigated mitral annular and leaflet motion in isolation, CMR imaging allows assessment of both the temporal and spatial relationship of mitral annular and leaflet motion throughout the cardiac cycle. Such insights provided by CMR may be important in understanding various disease processes affecting the mitral valve and the impact of these on normal mitral valve function, and in developing techniques for the surgical repair of diseased mitral valves.
Six phases of mitral annular and leaflet motion were identified during the cardiac cycle:
(I) Ventricular systolic excursion
The excursion of the mitral annulus towards the LV apex was asymmetrical with greater excursion of the posterior annulus and leaflets (13.5 mm) compared to the anterior annulus and leaflets (12.0 mm). The septal-lateral diameter increased in size during this phase (27.0 mm to 31.4 mm) while the commissure-commissure diameter remained unchanged. Mean phase duration: 376 ms (42% of cardiac cycle).
(II) Leaflet opening and annular recoil
Mitral leaflet opening was followed closely by atrially directed recoil of the mitral annulus. Separation of the mitral leaflet edges was greatest in the middle of this phase. Mean phase duration: 164 ms (18% of cardiac cycle).
(III) Leaflet approximation
The mitral leaflets move to a partially closed position. Mean phase duration: 94 ms (10% of cardiac cycle).
(IV) Mid diastolic pause
This represents the phase of diastolic inactivity with the mitral leaflets drifting in a neutral position. Mean phase duration: 146 ms (14% of cardiac cycle).
(V) Atrial systolic excursion
Left atrial systole pulls the mitral annulus and impells more blood into the ventricle which increases the separation of the mitral leaflet edges. Mean phase duration: 131 ms (14% of cardiac cycle).
(VI) Leaflet closure
This marks the onset of systole.
CMR assessment and graphic 2-D display of the mitral valve gives new insights into the dynamic nature of mitral annular and leaflet motions through the cardiac cycle. This may be important in the understanding of disease processes affecting the mitral valve and its impact on mitral valve function, and in the design of flexible mitral annuloplasty rings or bands which would allow preservation of the normal dynamic mitral annular and leaflet motion following surgical repair.
This article is published under license to BioMed Central Ltd.