Original article
Mitral Annulus Size Links Ventricular Dilatation to Functional Mitral Regurgitation

https://doi.org/10.1016/j.echo.2005.01.011Get rights and content

We compared the impact of annulus size and valve deformation (tethering) on mitral regurgitation in the animal dilated cardiomyopathy model, and assessed if acute left ventricular volume changes affect mitral annulus dimensions. We performed 3-dimensional echocardiography in 30 open-chest dogs with pacing-induced cardiomyopathy. Mitral annulus area was calculated from its two orthogonal diameters, whereas valve tethering was quantified by valve tenting area measurement. Mitral valve regurgitant volume showed the highest correlation with annulus area (r = 0.64, P < .001), left atrial volume (r = 0.40, P < .01), and left ventricular end-diastolic volume (r = 0.37, P < .01). Regurgitant volume showed poorer correlation with valve tethering in both septolateral and intercommissural planes (r = 0.35 and r = 0.31, P < .05 for both). Annulus dimensions correlated with acute changes of left ventricular end-diastolic volume (r = 0.68, P = .002). Mitral annulus dilation is the strongest predictor of functional mitral regurgitation in this animal dilated cardiomyopathy model.

Section snippets

Methods

We analyzed the data of the consecutive canines with tachycardia-induced cardiomyopathy that were included in various experimental heart failure treatment protocols from January 2001 to July 2002.8, 9, 10, 11 All data were collected in a prospective manner. All animals received humane care in compliance with the “Guide for the Care and Use of Laboratory Animals” prepared by the Institute of Laboratory Animal Resources, National Research Council, and published by the National Academy Press

Results

Table 1 shows hemodynamic and echocardiographic parameters associated with dilated cardiomyopathy induction. Although echocardiography data at baseline and after cardiomyopathy induction were acquired with the animal in conscious and anesthetized state, respectively, the dramatic change of parameters can still be appreciated. Interestingly, the only parameter that was not changed was LV long-axis length in diastole. MR was detected by color Doppler mapping in 42/53 studies. If MR was present,

Discussion

In this study, we have shown that the amount of functional MR observed in the presence of global LV dilation is coupled to mitral annular dilation. Interestingly, MR showed no consistent association with mitral leaflet deformation or PM tethering. However, mitral annular dilation showed correlation with these previously described features of functional MR, which may indicate that they all relate to the same underlying process, with mitral annulus area a most easily quantified feature. Finally,

References (26)

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