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"What Is The Mitral Valve Annulus?" Asks Dana

Written By: Adam Pick, Patient Advocate, Author & Website Founder
Page Last Updated: June 6, 2025

Some patients want to know EVERYTHING before their operation - the valve anatomy, the surgical process, the recovery details. Other patients want to know absolutely NOTHING about their upcoming surgery. Many say to me, "Honestly Adam, I don't want to know a thing. The more I know, the more I will worry."

I can understand both positions. That said, this blog is for those who want to know everything - especially about the anatomy of the mitral valve. Dana just wrote to me, "Adam - Can you help me understand what the mitral valve annulus is? My sister needs mitral valve replacement surgery due to regurgitation and that term - mitral valve annulus - came up in our last discussion."

No problem Dana. To start, please look at the two figures below. You can see a top- and side-view of the mitral valve. The posterior and anterior annulus is labeled on both diagrams.

Top View Of Mitral Valve

As you can see, the mitral valve annulus is a saddle-shaped structure that supports the leaflets of the mitral valve. (Unlike the other three heart valves, the mitral valve has two leaflets that manage the flow of blood through the mitral valve.)

Side View Of Mitral Valve

If the mitral valve annulus fails to properly connect with the leaflets or experiences significant calcification (see picture below), the functioning of the heart may be compromised. Both mitral valve regurgitation and stenosis can result.

For example, a mitral valve prolapse occurs when the mitral valve leaflets are displaced more than 2 mm above the mitral valve annulus high points. The condition can be further divided into classic and nonclassic subtypes based on the thickness of the mitral valve leaflets - up to 5 mm is considered nonclassic, while anything beyond 5 mm is considered classic mitral valve prolapse.

Written by Adam Pick - Patient & Website Founder

Adam Pick is a heart valve patient and author of The Patient's Guide To Heart Valve Surgery. In 2006, Adam founded HeartValveSurgery.com to educate and empower patients. This award-winning website has helped over 10 million people fight heart valve disease. Adam has been featured by the American Heart Association and Medical News Today.

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