Mitral valve repair has been popularised by Carpentier and others and now represents a recognised option in the treatment of mitral valve disease. Advocates argue that all mitral valves should be considered for repair first, and only those that are not suitable should be replaced. Mitral valve repair offers real advantages over replacement, chiefly low operative risk (around 2%1,2), avoidance of the risks of long term anticoagulation (in patients who are in sinus rhythm), very low risk of endocarditis, and probably better long term preservation of left ventricular function. The last aspect may not be as clear cut as once thought as techniques to replace the mitral valve while still preserving the sub-valvular chordal apparatus, which is so important in regulating ventricular geometry, may offer many of the advantages once held to be the sole preserve of repair techniques.3 A potential disadvantage of mitral valve repair is the less certain surgical outcome of the technique which relies on a greater degree of judgement, and the possible need for future redo surgery in around 10% of cases. The standard use of annuloplasty rings has improved results and reduced the need for redo surgery, but not to zero, and this point needs to be discussed with patients prior to choosing an approach.
Different valvular lesions are more or less amenable to mitral valve repair, and require that different techniques be employed:
Increased leaflet motion (Carpentier type II)
The patient with pure mitral regurgitation due to either a floppy myxomatous valve, or posterior leaflet chordal rupture represents the easiest and most successful case and the valve can be repaired by quadrangular resection of the posterior leaflet. Repair of anterior leaflet prolapse is a more complex undertaking and requires either a transfer of chordae from the posterior to the anterior leaflet, or the use of synthetic chordae. An alternative is to suture the free edges of the two leaflets together at their mid-points creating a double orifice valve, the so called Alfieri bow-tie repair.
Normal leaflet motion (Carpentier type I)
In some patients annular dilatation contributes to mitral regurgitation and requires correction with an annuloplasty ring.
Decreased leaflet motion (Carpentier type III)
This is the most difficult lesion to correct. It may require a combination of leaflet augmentation using patches of pericardium, and also elongation or replacement of any restricted chordae. Restricted leaflet motion due to poor ventricular function remains a particularly difficult problem to correct by repair techniques.
Features which indicate a low chance of successful repair
These include:
- Rheumatic valvular disease
- Thickened valve leaflets
- Multiple mechanisms of valve dysfunction
- Extensive prolapse of both leaflets
- Commissural regurgitation
- Annular calcification
- Dissection of valve leaflets complicating endocarditis.
In general all valves that can be repaired should be, although some patients may opt for valve replacement to avoid the (small) risk of needing further surgery due to failure of the repair. Because of the low operative risk, absence of the need for anticoagulation and avoidance of the risks of prosthetic valve endocarditis following valve repair, a further group of patients may be offered valve repair at an early stage of their disease where, on the balance of risks, valve replacement would not yet be justified.
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