Atlas of Mitral Valve Repair, 1st Edition

5

Overview of Mitral Valve Repair

PREOPERATIVE AND PERIOPERATIVE ASSESSMENT

Details of the assessment of the mitral valve with echocardiography are reviewed in Chapter 4. It is important to review the echocardiogram prior to beginning the operative procedure. The echocardiogram will provide dynamic details about the abnormality of the valve that are unavailable with the heart arrested, such as which leaflet prolapses—the posterior, the anterior, or both? Does the whole leaflet prolapse or part of the leaflet? Where is the jet, central or lateral? Which direction is the jet positioned? Anteriorly— suggesting posterior-leaflet pathology, or posteriorly—suggesting anterior leaflet pathology. Are their ruptured chords? Is the annulus dilated? Is there calcification in the annulus or leaflet? Is leaflet motion restricted? This provides valuable information when deciding how to complete the repair.

An important area to focus on is the location and degree of prolapse. The anterior leaflet is considered to prolapse if it protrudes above the annular plane during systole. When assessing the anterior leaflet in the flaccid arrested heart it will always appear to prolapse, emphasizing the value of reviewing the echocardiogram.

Once the heart is arrested and the atrium is opened, inspection of the atrium and valvular structures will determine the necessary components of the repair. Adequate visualization of the valve is important. The mitral valve can be approached via transseptal or right lateral approaches. Visualization via the lateral approach is facilitated by dissection of the intraatrial groove.

Jet lesions in the atrium can direct attention to the site of abnormality. Hooks allow examination of the leaflets and subvalvular apparatus for mobility and integrity. Classifying the leaflet abnormality as Types I, II, or III will also guide the repair (Figs. 5.1,5.2,5.3,5.4,5.5,5.6,5.7).

GENERAL PRINCIPLES OF REPAIR

The goal of the various repair techniques is to identify the abnormality causing the leak then repair or compensate for the abnormality. Ideally correct application of repair techniques will produce appropriate coaptation. The rough zones of the leaflet should be in contact. The ratio of leaflet surface area to valve orifice area should be corrected to its natural 2:1 ratio. Because annular dilatation is a component of chronic mitral regurgitation, some type of annular support is necessary. Annuloplasty often completes the repair but cannot compensate for an inadequate repair.

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Figure 5.1 Dissection of the intraatrial groove. (Clip 2, Case 5) 

 

Figure 5.2 Intraoperative evaluation demonstrating a myxomatous valve with bileaflet proplapse and posterior stretched chords. . (Clip 1, Case 6) 

 

Figure 5.3 Intraoperative evaluation demonstrating a myxomatous valve with a posterior flail leaflet and ruptured chords to P2 and a P1-P2 cleft. (Clip 2, Case 1) 

 

Figure 5.4 Intraoperative evaluation demonstrating a rheumatic valve with stiff leaflets, commissural and cleft fusion, and thickened, shortened chords. (Clip 2, Case 3) 

 

Figure 5.5 Intraoperative evaluation demonstrating anterior leaflet prolapse. (Clip 2, Case 4) 

 

Figure 5.6 Intraoperative evaluation demonstrating normal leaflet structure and a dilated annulus. (Clip 3, Case 2) 

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Figure 5.7 Intraoperative evaluation demonstrating a normal appearing valve with a dilated annulus. (Clip 3, Case 5) 

Sequence of Repair

In general, sequential performance of the components of repair should be logical with previous steps supporting subsequent steps. After analyzing the defects and deciding on the necessary components, placement of the sutures that will be used to secure the annuloplasty ring will help bring the valve into view. Leaflet components should be repaired before performing procedures to secure leaflet excursion. Securing the ring in place prior to tying artificial chordae will allow for more accurate length determination.

Suture Material and Placement

For suturing the leaflets, fine 4-0 monofilament suture (e.g., polypropylene) has been recommended. However, Lim et al. reported reoperation necessitated by perforation of the apposing leaflet by the stiff tail of a polypropylene suture used for a previous leaflet repair (1). They recommend using a soft braided suture (e.g., polyester) for leaflet repair. For insertion of the annuloplasty ring or band 2-0 braided polyester sutures are adequate. For artificial chordae 2-0, 4-0, or 5-0 Goretex is recommended. One author considers 5-0 too weak and prone to rupture.

GENERAL PRINCIPLES FOR CLOSURE OF LEAFLET DEFECTS

Whether closing a gap at the commissure or between scallops or closing a defect after leaflet excision, the suture repair must be strong and must not distort the leaflet anatomy. The sturdiness of the tissue is very important. Thin tissue will not hold sutures and will easily tear. Avoid creating pleats in the valve tissue and foreshortening it by using an interrupted or a running-locking suture (Fig. 5.8). An additional advantage of a running-locking suture is to avoid knots at the site of leaflet apposition.

 

Figure 5.8 Running-locking suture to prevent crimping along the suture line. The suture is started at the edge and tied on the ventricular side of the leaflet, then brought up through the atrial side. Sutures are placed horizontally, locking the previous loop then pulled up and set before the next suture bite is taken.

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One-Leaflet versus Two-Leaflet Repair

The goal of the classic principles of mitral valve repair outlined above is to create two functional leaflets. Specifically if both leaflets prolapse then reparative techniques must be applied to both. Another alternative is to simplify the task by repairing the posterior leaflet to function as a buttress for the anterior leaflet, creating a functional unileaflet valve. This concept was specifically addressed by Gillinov et al., examining the outcomes in patients who had bileaflet prolapse with no chordal abnormalities (rupture or elongation) that underwent isolated posterior-leaflet repair and annuloplasty (2). This approach was preferentially used in 93 patients with excellent long-term results (3).

REFERENCES

  1. Lam BK, Gillinov AM, Cosgrove DM 3rd. Failed mitral valve repair caused by polypropylene suture. Ann Thorac Surg.2003; 76:1716-1717.
  2. Gillinov AM, Cosgrove DM 3rd, Wahi S, et al. Is anterior leaflet repair always necessary in repair of bileaflet mitral valve prolapse? Ann Thorac Surg.1999; 68:820-823.
  3. Cho L, Gillinov AM, Cosgrove DM 3rd, et al. Echocardiographic assessment of the mechanisms of correction of bileaflet prolapse causing mitral regurgitation with only posterior leaflet repair surgery. Am J Cardiol.2000 Dec 15; 86(12):1349-1351.