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