Mitral Annulus Anatomy
Understanding mitral valve anatomy provides the foundation to appreciate its intrinsic valvular abnormalities. Continuing advancements in cardiac imaging allow for visualization over three dimensions.10
The mitral annulus is a junctional region between the left ventricle and the left atrium. It is saddle-shaped and will experience dynamic changes throughout the cardiac cycle (see Figure 1 for mitral valve anatomy).11,12
Annular diameter correlates with function and has shown to be impaired secondary to valve pathologies such as myxomatous disease and cardiomyopathies. With respect to myxomatous disease, the mitral annulus will dilate in all planes. The increase in diameter will inhibit regurgitation prevention mechanisms. In comparison, there is an isolated anterior-posterior enlargement with ischemic cardiomyopathy. Annular remodeling will vary depending on the pathophysiology of the underlying disease process.13
Physiological degrees of mitral annular incoherence have been isolated in “normal” patients and whether this represents early signs of dysfunction or a mere physiological variant is yet to be determined. However, it is important to appreciate that, histologically, the annulus is a non – continuous structure and its thickness will vary depending on the density of collagen.14