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Mitral annulus disjunction

The normal, human heart has four chambers: the right and left atria, and the right and left ventricles.

The mitral valve is composed of two  leaflets, allowing blood to flow from the left atrium to the left ventricle when it relax. The leaflets are attached to a fibrous ring known as the mitral annulus. Normally, the mitral annulus is anchored to the left ventricle . Mitral annulus disjunction (MAD) is a structural abnormality where the mitral annulus is not correctly connected to the left ventricle, which may lead to mitral valve prolapse (MVP).

MVP is a frequent valve disorder, with a prevalence of about 2% in the general population and a good overall prognosis. MVP often leads to leakage in the mitral valve. Importantly, a subset of patients with MVP are at risk of sudden cardiac death due to arrhythmias. The mechanisms for arrhythmias are largely unknown, but MAD may be the arrhythmogenic factor. The genetic background of both MAD and MVP is also largely unknown and therapeutic strategies are not studied.

Image: Basso et al. Circulation 2019 (modifisert og oversatt)