A New Paradigm for the Repair of Posterior Leaflet Prolapse: Respect Rather Than Resect

Postoperative echocardiocardiography showing the extent of the surface of coaptation.

Exposure. Neochordal repair of the posterior leaflet is a versatile technique that can be applied via sternotomy or with a minimally invasive approach. Whatever the approach, the first critical step is to have an optimal and stable exposure of the mitral valve. All the tips and tricks of each method are to be used to obtain a full view of the mitral valve. To improve exposure, a 3-0 suture is passed around and below the inferior vena cava. Next, it takes a superficial bite of the left atrial endothelium of the left atrial endothelium about 1.5 cm behind the mitral valve annulus, at approximately 5 o’clock on the mitral annulus, and then passes back behind and below the inferior vena cava. Applying a gentle tug on this suture will improve the exposure of the mitral valve. Time may have to be spent to achieve this result, but it will be regained all along the operation.

Valve analysis. Once the desired exposure is achieved, a thorough surgical valve analysis is performed. Usually, the anterolateral scallop of the posterior leaflet (P1) is free from prolapse and can be used as a reference point to compare all other segments. With the help of a nerve hook, the free edge of P1 is compared with A1, then with A2, P2, A3, and P3. By using such a step-by-step exploration of the entire mitral valve, it is possible to achieve a good three-dimensional understanding of the mitral valve. This maneuver should clearly show the prolapse of the posterior leaflet located in P2 in which the free edge of the posterior leaflet overrides the free edge of the anterior leaflet because of the ruptured chords. The result of the surgical valve analysis should be compared with the intraoperative echocardiographic findings. The time spent to understand the dysfunction and to recognize the lesions is critical for a successful operation. Failure to perfectly understand the mechanism of the mitral dysfunction may lead to a failure of the repair.

Analysis of the prolapsed area. Once the prolapsed area of the posterior leaflet is identified, one 2-0 stay sutures are passed around normal chordae on each side of the prolapsed area of the posterior leaflet to delineate the pathological zone. Gentle exertion of the suture will provide exposure to the prolapsed area. Analysis of the prolapsed area is directed toward 2 aspects of the tissue: the quality of the tissue and the quantity/amount of tissue which corresponds to the height of the posterior leaflet in this area.

The quality of tissue. The aim of the operation is to construct a vertical buttress in which the surface area should be smooth, flat, and regular to ensure an even surface of coaptation. From time to time, mucoid degeneration is too anarchic, producing bulging pockets and making the surface of coaptation uneven and irregular. In such a case, a localized resection to remove this pathological uneven area is necessary.

It may also happen that the mucoid process is too excessive at the base of the posterior leaflet, reducing the pliability of the junction between annulus and leaflet. This can displace the surface of coaptation anteriorly, which may increase the risk of SAM. A localized resection is also needed in such a case.

The quantity of tissue. It is at this point that the height of the posterior leaflet is evaluated. An excess of tissue is present when the height of the posterior leaflet exceeds 2 cm. It is important to take note of this situation, because it will affect the length of the artificial chordae to be used.

Placement of e-PTFE through the papillary muscle. To provide a better view of the subvalvular apparatus, 2-0 stay sutures are passed around chordae of the anterior leaflet arising from the anterior and posterior papillary muscle. In most cases, two are usually sufficient. Gentle traction on these sutures, when combined with gentle pulling on the stay sutures of the posterior leaflet, provides good views and access into the left ventricular cavity and to the papillary muscles. With a forceps, it is then convenient to grasp the anterior papillary muscle to improve its exposure and stability. A mattress suture of 4-0 e-PTFE is placed through the fibrotic part of the top of the anterior papillary muscle. It is desirable that the exit point of this suture is oriented toward the prolapsed area. The suture is then tied down (3-4 knots) on the papillary muscle. The same maneuver is repeated for the posterior papillary muscle. If the prolapsed area is greater than the middle portion of P2, additional artificial chordae may be needed. It is important that these sutures are placed through the papillary muscle head that anchors the diseased chordae to respect the geometry of the subvalvular apparatus.

Placement of e-PTFE through the free edge of the posterior leaflet. The 2 e-PTFE sutures are then brought up through the free margin of the leaflet. One suture is placed between the indentation P1-P2 and the middle of P2, and the other suture between the middle of P2 and the indentation P2-P3. The double-armed sutures are brought from the auricular side of the leaflet directly at the free edge, where the original chordae are attached to the ventricular side and then back to the auricular side 4 mm to 5 mm from the free edge. The distance between the 2 arms of a suture should be approximately 3 mm to avoid plication of the tissue, which would impair the smoothness and regularity of the surface of coaptation.

Placement of e-PTFE through the free edge of the posterior leaflet. The 2 e-PTFE sutures are then brought up through the free margin of the leaflet. One suture is placed between the indentation P1-P2 and the middle of P2, and the other suture between the middle of P2 and the indentation P2-P3. The double-armed sutures are brought from the auricular side of the leaflet directly at the free edge, where the original chordae are attached to the ventricular side and then back to the auricular side 4 mm to 5 mm from the free edge. The distance between the 2 arms of a suture should be approximately 3 mm to avoid plication of the tissue, which would impair the smoothness and regularity of the surface of coaptation.

Tying the e-PTFE at the proper length. The next step is to tie off the artificial chordae at the proper length. The stay sutures of the posterior leaflet are removed, so that the free edge may be freely mobilized. The goal is not only to correct the prolapse, but also to transform the posterior leaflet into a vertical buttress against which the anterior leaflet will come into apposition. It is important that the free edge of the posterior leaflet will not be able to move anteriorly toward the outflow tract of the left ventricle. The length of the artificial chordae is selected to compensate for any excess of tissue of the posterior leaflet. If there is no excess of tissue, then the artificial chordae length is selected to bring the free edge of the posterior leaflet to the level of the plane of the annulus as shown in Fig 7A. If there is excess of tissue, then the artificial chordae length is selected to bring the free edge of the posterior leaflet to a lower level, typically between 5 mm to 8 mm underneath the plane of the annulus, depending on the height of the posterior leaflet, as shown in Fig 7B. Once the free edge has been brought at the desired level, the e-PTFE sutures are gently tied on the atrial surface (3-4 knots are necessary).

Tying the e-PTFE at the proper length. The next step is to tie off the artificial chordae at the proper length. The stay sutures of the posterior leaflet are removed, so that the free edge may be freely mobilized. The goal is not only to correct the prolapse, but also to transform the posterior leaflet into a vertical buttress against which the anterior leaflet will come into apposition. It is important that the free edge of the posterior leaflet will not be able to move anteriorly toward the outflow tract of the left ventricle. The length of the artificial chordae is selected to compensate for any excess of tissue of the posterior leaflet. If there is no excess of tissue, then the artificial chordae length is selected to bring the free edge of the posterior leaflet to the level of the plane of the annulus as shown in Fig 7A. If there is excess of tissue, then the artificial chordae length is selected to bring the free edge of the posterior leaflet to a lower level, typically between 5 mm to 8 mm underneath the plane of the annulus, depending on the height of the posterior leaflet, as shown in Fig 7B. Once the free edge has been brought at the desired level, the e-PTFE sutures are gently tied on the atrial surface (3-4 knots are necessary).

The e-PTFE sutures are passed on the ventricular side of the leaflet. The artificial chordae are then passed again through the leaflet tissue, and then tied on the ventricular surface. Because it is a rather slippery material, a total of 10 to 12 knots are necessary, which leaves a rather prominent remnant. There are two reasons to tie the knots on the ventricular side: to avoid any irregularity of the surface of coaptation due to the prominent remnant and to avoid any motion of the leaflet along the artificial chordae, which may create unnecessary repeated tension on the leaflet and/or chordae.

Suture of the indentations. The indentations between P1 and P2 and between P2 and P3 are analyzed. If they are deep, they may interfere with the goal of transforming the posterior leaflet into a smooth and regular vertical buttress. In a natural mitral valve, these indentations serve the physiological purpose of making possible for the posterior leaflet to expand and to follow the diastolic dilation of the annulus without tension on the free edge. However, because the annulus is to be fixed into the systolic position by the implantation of an annuloplasty ring, the indentations will no longer serve their useful role. On the contrary, the indentions may be the cause of residual leak attributed by an irregular surface of coaptation. Accordingly, when the indentations are deep, it may be desirable to suture them with a 5-0 monofilament running suture, as shown in Fig 9, to ensure a perfect result of the repair.

Ring implantation and valve testing. Two to 0 braided sutures are passed through the mitral annulus and then into the annuloplasty ring. The sutures should be placed in a way in which they respect the geometry of the mitral valve. Routinely, 4 sutures are placed at the level of the anterior leaflet between the 2 commissures. It is important that the middle of the anterior leaflet corresponds to the middle of the ring to avoid any distortion of the mitral valve.

The role of the ring is not only to reduce the size of the annulus but also to remodel the shape of the mitral valve, which has been deformed as a consequence of the mitral valve insufficiency. In fixing the mitral valve in a systolic position, the ring will prevent any further annular dilation. The size of the ring is selected according to the surface area of the anterior leaflet and/or the intertrigonal distance, as in any other repair of organic mitral valve disease.

After ring implantation, and before closure of the left atrium, the result of the repair is tested by injecting saline solution into the left ventricle. Two points are important; the absence of regurgitation and the aspect of the line of closure. The line of closure should be symmetrical, close to the ring, and parallel to the posterior aspect of the ring. A posterior line of closure is a sign that the surface of coaptation is away from the outflow tract.

After closure of the left atrium and normal hemodynamic function is restored, an echocardiographic analysis will control the quality of the result. The absence of regurgitation as well as a free outflow tract will signal a successful repair. The height of the surface of coaptation can be measured, usually between 12 mm and 18 mm.