Type II posterior leaflet dysfunction is the most frequent dysfunction in mitral valve regurgitation caused by degenerative valvular disease. It can also be encountered in other etiologies such as bacterial endocarditis, and even rheumatic valvular disease in young children. The prolapse usually affects P2 but can be extended to P3 and more rarely P1. It is generally due to chordae rupture and/or elongation. A special feature of this dysfunction is the important secondary lesions affecting the prolapsed area. Over time the leaflet tissue becomes distended with proliferation of pathological tissue: the P2 segment may be two to three times the normal size. The consequence is that some portion of the excess tissue should be resected to restore a more normal valve geometry, to reduce the tension on the remaining chordae, and to stop progression of the process. The tension is reduced as a consequence of Laplace’s law, which states that the larger the radius of a portion of a sphere (i.e., the prolapsed leaflet) the greater the tension on its surface, and therefore on the chordae. As shown by very long-term results, this approach effectively prevents recurrent regurgitation in most cases. An additional advantage is that it is an easy and reliable technique, which does not require surgical correction at the subvalvular level .
Resection of a portion of excess leaflet tissue is preferable in posterior leaflet prolapse to reduce the tension on the remaining leaflet tissue and chordae.
Several techniques of reconstruction can be used depending upon the extent and mechanism of the leaflet prolapse ( Table 11-1 ).
| Limited Prolapse | Extensive Prolapse | ||
|---|---|---|---|
| <⅓ of Free Margin of Leaflet Segment | >⅓ of Free Margin of Leaflet Segment | 1 Entire Leaflet Segment | |
| Technique | Triangular leaflet resection | Quadrangular resection and annular plication | Quadrangular resection and sliding leaflet technique |
| Alternative Techniques in Chordae Rupture | Chordae transposition or replacement | Chordae transposition or replacement | Composite technique |
| Alternative Techniques in Chordae Elongation | Chordae shortening | Chordae shortening | Composite technique |
LIMITED PROLAPSE
A limited prolapse is a prolapse involving less than one third of the free margin of a posterior leaflet segment. Whenever the prolapsed segment displays only a small amount of excess tissue and discrete secondary lesions, chordae transposition or chordae replacement are elegant solutions. Most of the time, however, excess tissue or pathological tissue makes a limited triangular resection preferable, which has the advantage of operating at the valvular level and reducing the tension on the remaining leaflet and chordae. The degree of resection depends upon the extent of the prolapse and amount of grossly abnormal tissue.
Triangular Leaflet Resection
This technique evolved from the historical McGoon’s plication technique (inset) , which was efficient but had the single disadvantage of leaving a segment of pathological tissue, which could later cause fibrous proliferation or leaflet retraction. A triangular leaflet resection ( Fig. 11-1 ) avoids this drawback. It is indicated whenever the length (B) of the free margin of the prolapsed segment is limited to less than one third of the total length (A) of the leaflet segment involved (B ≤ A/3) (b) .
To perform a limited triangular resection, two 2-0 stay sutures are passed around the non-elongated chordae at the limits of the prolapsed portion of the leaflet (c) . The height (H) of the triangular resection should be slightly longer than its base (H > B) (c) . Its sides are cut slightly convex so as to preserve the curvature of the reconstructed leaflet (d) . Leaflet continuity is restored using 4-0 or 5-0 interrupted sutures (e, f) . Depending upon the thickness of the tissue, these sutures can be inverted, with the advantage that the knots are positioned on the ventricular side of the leaflet (g) . A continuous suture technique is not recommended because it impairs leaflet pliability and has the tendency to produce a purse-string effect. Once the sutures have been completed, a nerve hook is used to detect any residual defect, which would be corrected by an additional everted suture (h) . Once the leaflet continuity has been restored, the adjacent indentations are carefully examined to assess whether their edges have been separated, a potential source of leak. In this case the open indentation must be closed by two or three interrupted sutures (i) .
Transposition or Replacement of Chordae
When the prolapsed leaflet segment does not present a significant amount of excess pathological tissue, transposition of secondary or basal chordae to the free edge of the leaflet or chordae replacement are valuable alternatives. These techniques are described in Chapter 10 .
Chordae Shortening
When the prolapse is due to chordae elongation in the absence of significant excess tissue, one of the techniques of chordae shortening illustrated in Figure 10-12 can be used.
EXTENSIVE PROLAPSE
Extensive prolapse of the posterior leaflet involves more than one third of the length of the free edge of the corresponding segment ( Fig. 11-2, a ). In this case, chordae transposition or replacement is not advisable because it would leave excess tissue and therefore excess tension on the reconstructed leaflet and chordae. A large triangular resection is not recommended either because it would produce excess tension on the free edge of the leaflet, resulting in restricted leaflet motion (curtain effect) and separation of one or two adjacent indentations, a source of new sites of regurgitation (b) . These drawbacks are prevented by performing a leaflet quadrangular resection and annular plication, which reduces the tension on the leaflet remnants (c) . The quadrangular resection can be symmetrical or asymmetrical (d) , depending upon the location of the prolapse. This does not influence the technique.
A large triangular resection of the free edge of a leaflet may cause tenting of the free edge and separation of the indentations.
Quadrangular Resection with Annular Plication
This technique ( Fig. 11-3 ) is the most frequently used technique in posterior leaflet prolapse. It has the advantage of removing most pathological tissue, restoring a more normal geometry of the leaflet, and reducing the tension on the suture line of the reconstructed leaflet. The technique is simple and efficient and does not require surgery at the subvalvular level. The resection should be quadrangular with a slight trapezoidal shape and should be completed by a plication of the annulus to approximate the leaflet remnants.
Quadrangular resection of the prolapsed area with annular plication is used only in extensive posterior leaflet prolapse.
The normal chordae at the limits of the prolapse area are identified (a) . Approximately 2 to 3 mm from these normal chordae, a line of resection is projected from the free margin down to the annulus so that a trapezoid or a rectangle is formed. Whenever possible it is preferable to keep one or two indentations to facilitate the opening motion of the posterior leaflet . The leaflet tissue delineated by the trapezoid is resected (a) . The secondary chordae, close to the edges of the resection, are cut to facilitate leaflet mobilization (b) . The height of the posterior leaflet remnants is then measured. Whenever the height of the remnants is <20 mm and the residual gap is <20 mm (c) , a plication of the annulus is used (d) .
An interrupted 2-0 mattress suture is placed through the annulus at the limits of the resected area (e) . Exerting traction on this suture facilitates placement of another interrupted figure-of-eight suture to close the plicated annular segment (f) . Pledgets are not necessary since the prosthetic ring that will be implanted ensures adequate repartition of the stress. The sutures are tied, making sure that the two leaflet remnants are well approximated. If this is not the case, an additional suture is used, taking a larger bite on the annulus (g) .
The leaflet continuity is then restored (h) using everted or inverted 5-0 sutures. The suture line is examined to identify occasional residual defects (i) , which should be repaired by additional everted stitches (inset) . The repair is completed by the implantation of a prosthetic ring.
Quadrangular Resection with Leaflet Height Adjustment
When the height of one leaflet remnant ( Fig. 11-4, a ) or both remnants (b) measures more than 20 mm, a small horizontal triangular resection at the base of the leaflet remnant reduces the height to 15 mm. The edges of the leaflet remnants must be adjusted to the same length using continuous 4-0 sutures. Each detached remnant is reattached to the annulus while exerting gentle traction on the leaflet tissue (“sliding maneuver”) to reduce the gap left by the leaflet resection. The remainder of the procedure is unchanged from the procedure for quadrangular resection with annular plication, including annuloplasty.
