Functional anatomy of the normal mitral apparatus: a transthoracic, two-dimensional echocardiographic study.
OBJECTIVE
Normal mitral valve function relies on integrity of the leaflets, annulus, subvalvular apparatus, and the left ventricle. Echocardiography has contributed significantly to the understanding of normal and abnormal mitral valve function. Thus, plausible pathophysiologic mechanisms have been proposed for various etiologies of mitral regurgitation, based on echocardiographic measurement of a limited number of parameters. This study provides quantitative echocardiographic assessment of various components of the mitral valve-left ventricular (LV) complex.


METHODS
Mitral annulus, leaflets, papillary muscles and basal LV posterior wall length were measured at end-systole and end-diastole in 10 adults (7 females, 3 males; mean age 61 +/- 15 years) with structurally and functionally normal hearts. In addition, LV size and function and left atrial and aortic root sizes were measured.


RESULTS
Mitral valve competence in these normal hearts was achieved by systolic reduction in LV volume, diameter and length of 66%, 31% and 18%, respectively. The LV posterior wall (from mitral annulus to origin of the posteromedial papillary muscle) was shortened by 32%. The mitral annulus likewise showed a reduction in diameter of 6% in anteroposterior and 13% in mediolateral planes. Anterior mitral valve leaflet apposed with posterior leaflet by 23% in length in systole, whereas the papillary muscle shortened by 34%. The interpapillary muscle distance decreased by 51% in systole.


CONCLUSIONS
These data provide echocardiographic reference values for various components of the mitral valve-LV complex in normal adults. Further studies are needed to identify the relative significance of each of these components in the pathogenesis of mitral regurgitation of various etiologies.
Babburi
Haritha
H
Department of Medicine (Division of Cardiology), Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Oommen
Raju
R
Brofferio
Alessandra
A
Ilercil
Arzu
A
Frater
Robert
R
Shirani
Jamshid
J
D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D002815:Chordae Tendineae / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D003971:Diastole / Q000502:physiology; D004452:Echocardiography; D005260:Female; D006325:Heart Atria / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006352:Heart Ventricles / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D010210:Papillary Muscles / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D012016:Reference Values; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology; D016276:Ventricular Function