Mitral Valve Pathology and Surgery

The mitral valve guards the inflow between the left atrium and left ventricle, and its disease takes two principal forms: mitral regurgitation, in which the valve leaks during systole, and mitral stenosis, in which the valve fails to open fully. This topic covers the anatomy and mechanisms behind these lesions and the surgical responses to them, with repair of the leaking degenerative valve being one of the signal achievements of modern cardiac surgery.

Definition

Mitral valve pathology comprises the structural and functional disorders of the mitral valve — chiefly regurgitation and stenosis — and the surgical or transcatheter procedures (repair or replacement) used to correct them.

Scope

The entry addresses the structure of the mitral apparatus, the distinction between degenerative, functional, and rheumatic disease, Carpentier's functional classification of regurgitation by leaflet motion, and the surgical strategies of repair and replacement. It is a methodological and anatomical reference; it does not set out indications or thresholds for operating on a particular patient.

Core questions

• What distinguishes degenerative, functional, and rheumatic mitral disease?
• How does Carpentier's classification of leaflet motion guide the repair strategy?
• When is the mitral valve repairable rather than requiring replacement?

Key concepts

• Mitral regurgitation
• Mitral stenosis
• Degenerative (myxomatous) mitral disease
• Functional (secondary) mitral regurgitation
• Carpentier functional classification
• Annuloplasty
• Leaflet and chordal repair

Mechanisms

The mitral valve is an apparatus, not a single structure: its two leaflets depend on the annulus, the chordae tendineae, and the papillary muscles, and disease at any level can produce regurgitation. In degenerative (myxomatous) disease the leaflet tissue and chordae elongate or rupture, allowing a segment to prolapse and the valve to leak; in functional disease the leaflets are intrinsically normal but ventricular dilatation tethers them and dilates the annulus so they no longer coapt. Mitral stenosis, most often rheumatic, results from commissural fusion and leaflet thickening that obstruct inflow and raise left atrial pressure. Carpentier's functional classification organises regurgitation by leaflet motion — normal (type I), excessive/prolapse (type II), or restricted (type III) — and this framework maps directly onto the reconstructive techniques used to restore coaptation.

Clinical relevance

Mitral disease is a leading reason for valve surgery, and the durability of degenerative mitral repair has made it a reference example of valve-preserving surgery. This entry explains the mechanisms and surgical principles for educational reference; it does not provide operative timing or individualized recommendations, which belong to current clinical guidelines and the heart team.

Epidemiology

Degenerative mitral regurgitation is the most common form of primary mitral disease in higher-income populations and increases with age, whereas mitral stenosis is predominantly rheumatic and remains common in regions where rheumatic heart disease persists. Functional mitral regurgitation accompanies left-ventricular dysfunction of ischaemic or dilated origin.

History

Closed and then open commissurotomy were the first operations for mitral stenosis. The decisive shift toward valve preservation came with Alain Carpentier's reconstructive techniques and his functional classification, set out in his 1983 account of the "French correction", which established repair with annuloplasty as the preferred treatment for degenerative regurgitation. Transcatheter edge-to-edge and annular techniques later extended catheter-based options to selected patients.

Debates

How should functional (secondary) mitral regurgitation be treated?

Because the leaflets are normal and the problem lies in the ventricle, the benefit of correcting functional regurgitation — surgically or by transcatheter repair — and the durability of those corrections remain areas of active investigation and guideline refinement.

Key figures

• Alain Carpentier
• Maurice Enriquez-Sarano

Seminal works

• carpentier-1983
• enriquez-sarano-2009

Frequently asked questions

Why is repair often preferred over replacement for the mitral valve?

Preserving the native valve and its connections to the ventricle maintains ventricular geometry and avoids a prosthesis; in degenerative disease, durable repair is achievable in most cases. The general trade-offs between repair and replacement are covered in a separate topic entry.

What is Carpentier's classification?

It groups mitral regurgitation by the motion of the leaflets — normal, excessive (prolapse), or restricted — which helps the surgeon identify the mechanism of the leak and choose the matching reconstructive technique.