It is well accepted that the majority of patients with degenerative mitral valve disease who require surgery will have an improved quality of life with less morbidity and better long-term survival with valve repair as opposed to replacement.¹ This is attributable primarily to prosthesis-related morbidity, including higher reoperation rates, greater risk of endocarditis, and the need for anticoagulation with mechanical valves. Anticoagulation is particularly problematic for young, active patients and women in the child-bearing age group.

Therefore, when feasible, repair is preferred to replacement. The two keys to repair feasibility are the condition of the mitral valve and the experience of the surgeon. In most cases, mitral valve repair is technically no more complex than valve replacement. Mastery of only a handful of repair techniques enables repair of more than 90 percent of degenerative valves. A successful mitral valvuloplasty for degenerative disease provides most patients with an extremely durable valve, with many patients remaining free of reoperation 30 years after valve repair.²

The choice of repair technique for a given mitral valve depends upon the site of prolapse. We will present, in sequence, repair options for posterior, anterior, commissural, and bileaflet prolapse.

Posterior Leaflet Prolapse

Approximately 75 percent of patients with mitral regurgitation (MR) caused by degenerative disease have isolated prolapse of the posterior leaflet, most commonly the P2 segment (middle scallop).³ Several techniques have been developed to deal with this anatomical site of prolapse.

Quadrangular Resection

This is the classic technique for managing P2 prolapse, with or without a sliding repair.⁴ The sliding repair was developed to reduce the risk of postrepair systolic anterior motion (SAM) in the setting of excessive leaflet tissue and/or a small, hyperdynamic left ventricle.⁵ The classic quadrangular resection, which includes annular plication, is rarely employed today and has been largely replaced by a triangular resection technique. Similarly, a folding repair technique has replaced the sliding repair.

Triangular Resection

In the patient with segmental posterior leaflet prolapse, MR is caused by lack of leaflet coaptation at the site of posterior chordal rupture or elongation. Hence, it is logical to target the free edge of the prolapsing or flail leaflet.^6,7 A triangular resection comprises resection of the localized prolapsed or flail segment, with incisions in the leaflet angled toward one another as the incisions approach the annular level. No annular plication sutures are necessary. This simplified resection technique is particularly useful in minimally invasive right thoracotomy or robotic approaches as it saves operative time. As with most mitral repairs, this repair is completed with placement of a posterior flexible annuloplasty band (Fig. 36-1).

Folding Plasty

The folding plasty technique is used to treat posterior leaflet prolapse when there is a high risk of SAM, replacing the sliding repair for this indication.⁸ The prolapsing portion of the posterior leaflet is resected as for a quadrangular resection, leaving tall posterior leaflet remnants on either side (Fig. 36-2). A suture is passed through the midportion of the cut leaflet edge on each side, and this suture is then passed through the annulus at the midportion of the area of resection; this maneuver reduces the posterior leaflet height. If necessary, suture placement is modified to ensure that the leaflet remnants are of similar height. Leaflet tissue is then approximated to the annulus, closing the gap at the annular level and uniformly reducing the height of the posterior leaflet in this region. The leaflet edges are reapproximated centrally and an annuloplasty band completes the repair.

Artificial Chordae

There is growing enthusiasm for the use of artificial chordae to correct posterior leaflet prolapse. The chordae are constructed from ePTFE (Gore-Tex, W.L. Gore and Assoc, Flagstaff, AZ).

Two general chordal replacement techniques may be used. Chordal loops can be fashioned and affixed to a papillary muscle, creating multiple new chordae (loops) of the same length; usually this length is approximately 10 mm when treating posterior prolapse. Each of the chordal loops is attached to the free edge of the prolapsing leaflet with a figure-of-eight suture. The chordae are spaced on the leaflet edge at distances of 7 to 10 mm.^9,10 (Fig. 36-3)

Alternatively, a figure-of-eight ePTFE suture is taken through the tip of a papillary muscle, and then each needle is brought up through the free edge of the leaflet twice, each time from the ventricular to the atrial side. The annuloplasty band is placed next. Then the ventricle is insufflated with saline and the chordae are adjusted to a length such that there is no leakage. Care is taken when tying the chordae at the leaflet edge, as excessive tension at tying will cause the chordae to be too short, resulting in leaflet restriction (Fig. 36-4).

Anterior Leaflet Prolapse

Anterior leaflet prolapse has traditionally posed a challenge for surgeons performing mitral valve repair. Repair techniques include artificial chordae, chordal transfer, commissuroplasty, and the Alfieri edge-to-edge repair. Freedom from reoperation after anterior leaflet repair has been inferior to that after posterior repair. There is no question that repair of P2 leaflet prolapse by posterior resection and annuloplasty is technically simpler than anterior leaflet repair. However, standardization of anterior repair through the use of artificial chordae provides a relatively simple and durable repair.

Artificial Chordae

The key challenge in using artificial chordae is the proper determination of chordal length; there are many techniques for estimating chordal length.^9,10 If chordal loops are used, the surgeon uses a caliper to measure the length of a normal chord from the head of the papillary muscle to the level of the annulus. Chordal loops of this length—usually 21 to 23 mm—are constructed, affixed to a papillary muscle and then to the free edge of the leaflet. Alternatively, the free-hand technique for chordal construction can be used. As with posterior leaflet prolapse, this involves a figure-of-eight ePTFE suture passed through the papillary muscle, followed by two passes through the free edge of the prolapsing leaflet, and tying the suture with the annuloplasty band in place and the ventricle filled with saline to assure valve competence.

Chordal Transfer

This technique consists of excising a portion of the posterior leaflet with normal chordae and transferring it to support a portion of the anterior leaflet to which chordae have ruptured or elongated. Essentially, the posterior leaflet and its chords are “flipped over” to the anterior leaflet. The posterior leaflet is reconstructed in standard fashion and an annuloplasty band completes the repair (Fig. 36-5). The limitation of this technique is that it requires manipulation of a previously normal posterior leaflet in order to address anterior leaflet pathology. For this reason, we currently favor creation of artificial chordae to correct anterior leaflet prolapse.

Edge-to-Edge Repair

Described by Alfieri and coworkers, the edge-to-edge repair is the simplest maneuver for correction of prolapse.¹¹ With this technique, the prolapsing segment of the anterior leaflet is sutured to normal posterior leaflet directly opposite, ensuring coaptation and preventing prolapse. Sutures are taken several millimeters deep into the leaflet and span the entire region of prolapse. The suture line should not exceed 1 cm in length. Of note, the edge-to-edge technique can also be employed to manage posterior prolapse and bileaflet prolapse; however, it is rarely our primary repair technique for these pathologies.