• Both leaflets (which resemble a bishop's mitre, or "mitra")
• The attachments of the leaflets inside the valve's annulus
• The fibrous tendons (chordae tendineae)
• The papillary muscles

These four components have to work in harmony if the mitral valve is to open and close properly.



Repair is only possible if neither the annulus, valve leaflets, fibrous tendons or papillary muscles show any severe tissue changes, e.g. as a result of calcification or severe tissue thickening. Typically, reconstruction is only possible in cases that involve an enlargement of the valve apparatus, which results in the valve not closing properly (regurgitation).

Although pathological changes to any of these components will result in the disruption of normal valve closure, a number of components may be affected. A whole range of techniques are available that can restore individual components to their normal function. 



Annuloplasty

The shape and size of the annulus can be stabilized using a pre-shaped ring made of synthetic materials. 



Leaflet reconstruction

The valve leaflets can be tightened, reduced in size, or enlarged.



Chordal replacement / transposition

The chordae tendineae can be tightened, transposed, stretched or replaced/reinforced with artificial chords.



Papillary muscle shortening / transposition

The papillary muscles can be shortened or transposed. Their function, however, which is reminiscent of a parachutist actively pulling on the chords of a parachute, cannot be restored.



In an ideal case scenario, and even when different parts of the valve are severely affected, reconstruction can achieve results close to restoring normal function. However, a valve can only be restored to its full function in cases involving very minor, clearly defined changes. 



A diagnostic assessment using cardiac catheterization and echocardiography prior to surgery makes it possible to determine with certainty whether reconstruction is feasible. The final decision, however, can only be taken in the operating room, when the surgeon is able to examine the actual valve and perform tests to establish how well its components are functioning. This type of procedure can only be performed by a highly experienced surgeon, who is able to determine during surgery whether valve repair is likely to result in adequate valve function being restored. If valve repair is unlikely to restore adequate valve function, the procedure is neither viable nor advisable and, if this is the case, valve replacement surgery is the safer alternative.



All of these procedures can be combined as required in order to ensure adequate restoration of the valve and its function.

Mitral valve surgery can also be performed using minimally-invasive techniques. Even minimally-invasive procedures, however, require the use of cardiopulmonary bypass (a heart-lung machine), which is connected via the blood vessels in the groin. Access to the heart is via a small incision in the right side of the chest. As other sections of the heart cannot be reached, this type of surgery is only suitable in patients with isolated mitral valve defects. As with open surgery, this technique is suitable for both valve reconstruction and valve replacement. However, it cannot be used in patients who have developed adhesions in the chest following surgery or radiation therapy. In spite of this, Germany has seen a steady increase in the number of patients with isolated mitral valve defects being treated with minimally-invasive procedures.