Arq Bras Cardiol: Imagem cardiovasc. 2025; 38(1): e20250010
The Role of Objective Assessment of the Mitral Annulus
DOI: 10.36660/abcimg.20250010i
This Short Editorial is referred by the Research article "Mitral Annulus Diameter’s Relevance in the Diagnosis of Atrial Etiology in Mitral Regurgitation: A Comparative Analysis".
The mitral annulus is a complex and dynamic structure responsive to both structural and functional changes involving the mitral valve, as well as those affecting the geometry of the left ventricle (LV) and left atrium (LA). Its bean-shaped or “D”-shaped three-dimensional structure is similar to a horse’s saddle, in which the nadir (height) varies throughout the cardiac cycle. The malleability of the mitral annulus is important for valve competence. The posterior portion of the annulus, which is less fibrotic, moves during left ventricular systole, increasing the height of the saddle and reducing its circumferential area. In situations of left atrial dilation and dysfunction, mainly accompanied by atrial fibrillation (AF) and commonly associated with various causes of LV diastolic dysfunction, mitral annulus’ dynamics are often compromised. This results in reduced mobility of the posterior leaflet, annulus stiffness, and diminished oscillation of the saddle height, in addition to valve retraction (tethering), which contribute to mitral coaptation failure.
The mitral annulus can be studied using echocardiography, both two-dimensional and three-dimensional, with transesophageal imaging being the preferred approach. Three-dimensional imaging allows for various quantitative measurements facilitated by computational reconstruction software. These measurements can also be dynamic, capturing structural modifications throughout the cardiac cycle in both systole and diastole (). Key measurements include annular circumference and area, anteroposterior and inter-commissural diameters, and saddle height. The three-dimensional approach offers significant advantages, particularly when segmentation of valve anatomy is required, such as in cases of mitral valve prolapse that necessitate detailed anatomical analysis of valve bulges. Different etiologies of mitral regurgitation (MR) are accompanied by different degrees of mitral annulus deformation, with the most subtle ones observed in ischemic MR and the most significant in the most advanced spectra of mitral degenerative diseases, such as Barlow’s disease. For example, in rheumatic disease—still largely common in Brazil despite its low prevalence in more developed countries—mitral annulus changes are characterized by a “flattening of the saddle shape” and an increased area without a significant change in the perimeter.
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