Optimizing P2 Neochordal Length and Stability in Mitral Valve Repair With Use of a Polypropylene Loop

Technique

Four patients who had moderate-to-severe mitral insufficiency due to prolapse of the P2 segment and flail chordae tendineae were treated from June through November 2018. The patients were 2 men (aged 52 and 58 yr) and two women (aged 45 and 48 yr). Each provided written informed consent before treatment.

After placing the patient under general anesthesia, we performed a median sternotomy, then instituted bicaval cannulation, started cardiopulmonary bypass, and cooled the patient to 32 °C. Next, we cross-clamped the aorta and achieved cardiac arrest by means of cardioplegia. Through an incision in the Waterston groove, we resected redundant MV tissue in a triangular or quadrangular fashion and began primary repair. We placed sutures for the annuloplasty ring on the mitral annulus, then measured the annulus for ring size. After verifying that the posteromedial papillary muscle adjacent to the flail chorda was intact and functional, we placed a single 5-0 ePTFE suture (the future neochorda) with 2 felt pledgets onto the head of the muscle and tied it. We passed the ring sutures through the annuloplasty ring, and as we lowered it, we passed the ePTFE suture through the opening of the ring. Finally, we tied the ring sutures to fasten the ring to the annulus.

At this point, we modified the conventional procedure for measuring and fastening the neochorda. We used a 3-0 polypropylene suture to create a small loop posteriorly on the annuloplasty ring at the level of the P2 segment (Fig. 1A). Referring to an adjacent native chorda to estimate neochordal length, we marked the measurement in ink on the 5-0 ePTFE suture. We then passed both ePTFE needles through the prolapsed leaflet from the ventricular side to the atrial side and upward through the polypropylene loop, and repeated this action (Fig. 1A–B). Gently pulling up both sides of the ePTFE suture eliminated slack and brought the mark on the suture to the approximate level of the MV (Fig. 1C).

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Before tying the suture on the atrial side, we looked through the ventricular side to ensure that the papillary muscle had not been strained and that the neochordal length matched that of the adjacent chorda. We then tied the ePTFE suture to the valve's atrial surface (Fig. 1D). To ensure stability, we passed both needles to the ventricular side of the valve and tied the suture again. Finally, we cut and removed the polypropylene loop and completed the surgical procedure.

Intraoperatively, saline testing revealed that all patients had only mild MR, and this was confirmed on transesophageal echocardiograms after cardiopulmonary bypass was stopped. All patients recovered uneventfully and were discharged from the hospital. Their echocardiograms at one month showed trivial MR.

Discussion

Valve repair is the first treatment option for patients who have myxomatous MV disease, and it often involves using ePTFE sutures to replace chordae tendineae.⁶ Imprecise neochordal length and sliding after knotting are major challenges, and various proposed solutions have been suboptimal.

New techniques and minimally invasive surgery have helped to refine neochordal placement. An early repair method, in which a small tourniquet was used to adjust suture length, proved unsuitable when prolapsed areas were wide.⁷ In addition, using curved hemostatic forceps damaged ePTFE sutures, and knots slid when the suture was held gently during fixation.

Von Oppell and Mohr⁸ created an ePTFE chordal loop after using a ruler to measure for length. This widely used technique is the basis for many others; however, the suture loop can distort the leaflet.⁹

Surgeons have also referred to the MV annular plane when adjusting neochordal length. Rodriguez-Roda and colleagues¹⁰ passed threads of the annuloplasty ring's P2 central segment suture down into the ring with a 90° dissector and pulled them out at the commissural level beneath, thus keeping the threads in the annular plane. Instead, we used the mitral ring as the annular plane of reference. Placing the 3-0 polypropylene suture loop posteriorly on the annuloplasty ring at the level of the prolapsed P2 segment enabled us to attain the appropriate basal-marginal chordal correspondence. After passing the neochordal suture twice through the mitral leaflet and polypropylene loop, we eliminated slack by pulling up both sides of the suture before tying the knot. In addition, marking the length of an adjacent chorda on the suture enabled neochordal adjustment.

When MR involves the P1 and P3 segments, patients need to undergo more complex procedures with more neochordae, increasing the challenge. We decided to apply our technique to P2 prolapse only. We did not consider using it in patients who had undergone previous MV surgery, had wide prolapse, or were elderly.

We think that our use of a polypropylene loop to adjust neochordal length and ensure stability is simple, effective, and advantageous for surgeons who perform MV repair.