MMCTS
(November 29, 2005). doi:10.1510/mmcts.2004.000893
Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure
Quadrangular resection for repair of posterior leaflet prolapse
Patrick Perier*
Herz und Gefäss Klinik, Cardiac Surgery, Salzburger Leite 1, D-97615 Bad Neustadt/Saale, Germany
* Corresponding author: * Tel.: +49-9771 662 416; fax: +49-9771 651 219. E-mail: pperier{at}club-internet.fr
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Summary
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Quadrangular resection is the gold standard technique with thirty years results for correction of posterior leaflet prolapse. In most cases, resection removes the prolapsed area, which will correct the dysfunction. The posterior leaflet is repaired with either plication of the annulus or with sliding plasty in the case of excess of tissue as seen in Barlow's diseases, to minimize the risks of systolic anterior motion (SAM). After a quadrangular resection, the insertion of a ring completes the repair.
Key Words: Mitral valve repair • Mitral prolapse • Mitral valve surgery • Posterior leaflet • Quadrangular resection • Systolic anterior motion
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Introduction
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Prolapse of the posterior leaflet is the most common dysfunction of the degenerative mitral valve [1] and has been the first abnormality of the regurgitant mitral valve to undergo surgical correction [2]. Quadrangular resection followed by either annulus plication [3] or sliding leaflet plasty [4,5] has become, over the years, the gold standard method to repair posterior leaflet prolapse. Unlike the anterior leaflet, the method for dealing with the posterior leaflet is straightforward and reproducible [6,7]. However, as shown by the STS database [8], or the Euro Heart Survey [9], the proportion of patients having a repair in comparison to replacement is only around 40%, and in most instances the majority of these were simple annuloplasty with no resection of the leaflets. This is a reminder that quadrangular resection is not just merely a technique that can be blindly applied. On the contrary, like all techniques of mitral valve repair, it requires a 3-D understanding of the dysfunction, a vision of the goal of restoring the surface of coaptation, and an experience that will help to answer strategically the different questions that may arise during the repair. The contribution of echocardiography is an absolute must requiring the need for a team approach with an echocardiographer.
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Surgical technique
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Intraoperative echocardiography
After the induction of general anaesthesia, a transoesophageal probe is placed. A detailed echocardiographic (Video 1) assessment is performed following a standardized protocol to examine the dysfunction:
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Video 1 Intraoperative echocardiography demonstrating a typical posterior leaflet prolapse Type II P2. The free edge of the posterior leaflet overrides the plan of the annulus.
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- A functional analysis allows to classify the dysfunction, in our case a prolapse of the posterior leaflet.
- A segmental analysis allows localizing the dysfunction in P1, P2 or P3.
The echocardiographic examination confirms the etiology of the mitral disease and recognizes the lesions. It also provides valuable information not accessible during the operation, like the dynamic aspect of the dysfunction, the size and shape of the left ventricle and the thickness of the interventricular septum. These points are critical since they point out the risk factors for SAM.
Valve exposure
A quadrangular resection may be performed minimally invasively with a limited right thoracotomy or via a total or partial sternotomy. This issue will not be raised in this work. Whatever the approach is, the exposure of the mitral valve must be excellent and stable throughout the operation (Schematic 1). This may be difficult and require some time and all extra techniques, but it is essential.
Valve analysis
A surgical valve analysis (Video 2) is the first step of the operation. Usually the anterior scallop of the posterior leaflet (P1) is free from prolapse and is used as a reference point to compare all other segments. With the help of nerve hooks passed around chordae, the free edge of A1 is compared to P1, then A2, A3, P2 and P3. Step by step, it is possible to get a good understanding of the mitral valve and to confront the results of the surgical analysis to the findings of intraoperative echocardiography.
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Video 2 Surgical valve analysis. Step by step, it is possible to get a good understanding of the mitral valve and to confront the results of the surgical analysis to the findings of intraoperative echocardiography.
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Quadrangular resection
The prolapsed area of the posterior leaflet is identified. 2-0 stay sutures are passed around normal chordae on each side of the prolapsed area. These stay sutures limit the prolapsed area and they improve the exposure (Video 3).
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Video 3 Identification and exposure of the prolapsed area of the posterior leaflet. The prolapsed area of the posterior leaflet is identified. 2-0 stay sutures are passed around normal chordae on each side of the prolapsed area.
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A gentle traction on the stay sutures will expose the prolapsed area well. The quadrangular resection is performed. It is advisable to leave 0.5 cm of tissue on both sides of the resection to reduce the extent of resection. This will leave, at the end of the operation, a 1 cm of free edge on the posterior leaflet unsupported by chordae, which is compatible with good function of the posterior leaflet. It is necessary to pay attention to the base of the resection; the annulus must be cleaned from any mucoïd or calcific deposit to facilitate the next steps of the operation. It is possible to resect up to 1/3 of the posterior leaflet, but when the prolapse is extensive, other techniques are to be used (Video 4).
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Video 4 Quadrangular resection of the prolapsed area.
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Quadrangular resection with annulus plication
In case of normal posterior leaflet, a 2-0 suture is placed through the mitral annulus 0.5 cm away from the base of the quadrangular resection on both sides. This suture will be used later on to secure the annuloplasty ring. A 2-0 figure of eight suture is placed through the annulus starting at the middle of the resected area and then 0.2 mm away from the base of the resected area. Tying this suture plicates the annulus, it is important that as a result, the two leaflet remnants come in close apposition with a little overlap (Video 5).
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Video 5 Plication of the annulus. A 2-0 figure of eight suture is placed through the annulus starting at the middle of the resected area and then 0.2 mm away from the base of the resected area. Tying this suture plicates the annulus.
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Quadrangular resection with sliding leaflet plasty
When there is excess tissue and the posterior leaflet height is greater than 2 cm, a sliding leaflet plasty is necessary to reduce the height of the posterior leaflet to minimize the risk of SAM. The posterior leaflet is detached from the annulus at a distance which is approximately twice as much as the width of the resected area (Video 6).
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Video 6 Posterior leaflet detachment for sliding plasty. The posterior leaflet is detached from the annulus of a distance which is approximately twice as much as the width of the resected area.
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When the excess of tissue is large, both sides of the posterior leaflet may be detached from the annulus (Schematic 2). When the excess of tissue is more localized, only one side may have to be detached. In any case, the length of the detachment should be atleast twice as much as the width of the resection.
2-0 annulus sutures are easily placed at the level of the detached posterior leaflet, since the mitral annulus is well exposed (Video 7 and Schematic 3).
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Video 7 Annuloplasty suture placement. 2-0 annulus sutures are easily placed at the level of the detached posterior leaflet, since the mitral annulus is well exposed.
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The posterior leaflet remnants are reattached to the annulus with a running 4-0 monofilament. Care has to be taken to start the sliding plasty from the beginning of the suture to ensure that tension on the posterior leaflet is regularly distributed and that the gap of the posterior leaflet is adequately covered. It is important that the posterior leaflet remnants come in close apposition with a little overlap (Video 8 and Schematic 4).
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Video 8 Reattachment of the posterior leaflet to annulus. The posterior leaflet remnants are reattached to the annulus with a running 4-0 monofilament.
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Last steps of the operation
The two leaflet remnants are affixed to each other with a running 5-0 monofilament. It is important that this suture is performed without any tension (Video 9).
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Video 9 Reapproximation of posterior leaflet remnants. The two leaflet remnants are affixed to each other with a running 5-0 monofilament.
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2-0 annuloplasty sutures are placed all around the mitral valve annulus (Video 10).
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Video 10 Annuloplasty suture placement. 2-0 annuloplasty sutures are placed all around the mitral valve annulus.
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The annuloplasty ring is sized according to the surface area of the anterior leaflet (Video 11).
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Video 11 Sizing annuloplasty ring. The annuloplasty ring is sized according to the surface area of the anterior leaflet.
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After placement of the annuloplasty ring (Video 12), valve competence is assessed by injecting saline into the left ventricle, or by giving anterograde cardioplegia to fill the left ventricle (Video 13). Not only should the mitral valve show good competency, but the line of closure should lie posteriorly and run parallel to the annuloplasty ring.
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Video 12 Placement of the annuloplasty ring.
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Video 13 Intraoperative testing. valve competence is assessed by injecting saline into the left ventricle, or by giving anterograde cardioplegia to fill the left ventricle.
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The post-repair transoesophageal echocardiogram (Video 14) confirms good results and studies methodically the surface of coaptation, ensuring that it does not move anteriorly towards the outflow tract of the left ventricle producing a SAM. The height of the surface of coaptation is also measured, ensuring that it is more than 8 mm (Photo 1).
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Video 14 Post-repair transoesophageal echocardiography. The post-repair transoesophageal echocardiogram confirms a good result.
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Photo 1 Image of the postoperative echocardiography showing the measurement of the height of the surface of coaptation.
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Results
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Long-term survival of patients after quadrangular resection for posterior leaflet prolapse is good [10]. Reoperations in patients having quadrangular resection were attributable to technical factors (residual regurgitation, SAM) which could have been recognized with the systematic use of intraoperative echocardiography, as proved by others [6]. Using either annulus plication or sliding leaflet plasty after quadrangular resection has maintained the incidence of SAM extremely low, about 1%. It has been shown that long-term survival was identical to expected survival when operating on patients with severe mitral valve regurgitation when they are still asymptomatic [11]. This strategy is particularly important for posterior leaflet prolapse since, with experience, it can be carried out in almost 100% of the patients with a very low operative mortality.
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Acknowledgements
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The author thanks Jinny Lee for her editorial assistance.
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References
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Summary
Introduction
