A new design for posterior leaflet resection, “butterfly resection,” is proposed. It is a combination of two triangular resections in the prolapsing posterior leaflet segment. This method minimizes resection in the target segment, and it prevents systolic anterior motion by reducing the height of the posterior leaflet according to the amount of excess tissue. We have used this technique for 60.4% (29 of 48) of posterior leaflet prolapse cases with zero hospital mortality and no morbidity. Postbypass transesophageal echocardiography identified no more than mild regurgitation and no sign of systolic anterior motion. During 13.1 ± 6.8 months of follow-up, patients neither died nor needed reoperation.
From the Division of Cardiovascular Surgery, Department of Surgery, Shiga University of Medical Science, Otsu, Japan.
Accepted for publication December 16, 2010.
Presented at the Annual Scientific Meeting of the International Society for Minimally Invasive Cardiothoracic Surgery, June 11–14, 2008, Boston, MA USA.
Address correspondence and reprint requests to Tohru Asai, MD, PhD, Division of Cardiovascular Surgery, Department of Surgery, Shiga University of Medical Science, Setatsukinowacho, Otsu, Shiga 520-2192, Japan. E-mail: firstname.lastname@example.org–med.ac.jp.
Quadrangular resection has been an established method for >20 years.1 Although artificial chordal implantation is becoming popular, the quadrangular resection is still widely used as a standard procedure for posterior leaflet prolapse. However, this technique predisposes to systolic anterior motion (SAM) for at least two reasons: it leaves a relatively tall posterior leaflet when the posterior leaflet is high or redundant in areas adjacent to the excised quadrangle; and it requires annular circumference reduction by plication. Most cases of intraoperative SAM can be managed with volume loading and by stopping inotropic drugs, but some cases require immediate revision of the repair or replacement of the mitral valve. Where a risk of SAM is anticipated, specific repair techniques are preferred. Sliding plasty can sufficiently reduce the height of a posterior leaflet and will often prevent SAM,2 but it requires excessive leaflet tissue resection with annular plication and increases the complexity of the repair. Folding plasty also reduces the height of the posterior leaflet,3 but it may cause leaflet distortion. Artificial chordae implantation seems also to prevent SAM when the neochordae pull the posterior leaflet down adequately into the left ventricle.4 However, the precise adjustment of the neochordal length needs experience, and results can be uncertain. Here we introduce the concept of “butterfly resection” (Fig. 1), which offers a solution for these problems. This technique can reduce the height of the posterior leaflet without annular plication, and shifts the coaptation line of the mitral leaflets to a safer distance from the ventricular septum, thus reducing the risks associated with SAM.
Butterfly resection is a combination of two triangular resections. The first resection, a shallow triangular resection, at the free margin is carried out between two intact chordae adjacent to the prolapsing segment (Fig. 2A). The second resection, a reverse triangular resection, has its base at the annulus (Fig. 2B). Then the conserved margins of leaflet are rotated toward the annulus (Fig. 2C), and sutured with 5-0 polypropylene sutures. The height of the new posterior leaflet is determined by the length of the free edges of the first triangle remaining after the excision of the second triangle. Plication is not necessary, and although annuloplasty is almost always added to butterfly resection, this does not involve circumferential reduction as with plication in other methods. The procedure is completed by mitral annuloplasty with a semirigid ring (Carpentier-Edwards Physio Annuloplasty Ring, Edwards LifeSciences, Irvine, CA USA) sized in accordance with the true size of the anterior leaflet (Fig. 2D).
Between November 2006 and December 2009, butterfly resection was used to repair prolapse of the posterior leaflet in 29 patients suffering from severe mitral regurgitation (mean age, 61 years; 22 men, 7 women; mean body surface area, 1.62 m2). These were 60.4% (29 of 48) of the whole series of posterior leaflet prolapse in the same period. All procedures were performed by the same surgeon (T.A.). Prolapsed segments were P1 in 2 patients, P2 in 20 patients, and P3 in 7 patients. These lesions were mostly chronic degenerative pathology, with chordal rupture in 22 patients (75.9%), chordal elongation in 6 patients (20.7%), and papillary muscle rupture in 1 patient (3.4%). The mean size of Physio Annuloplasty Ring was 28.6 mm. Concomitant procedures included nine maze, three coronary artery bypass, one aortic valve replacement, one tricuspid valve annuloplasty, and one atrial septal defect closure. Mean cardiopulmonary bypass and aortic clamp times of isolated butterfly resection repair were 95 and 67 minutes, respectively. Postbypass transesophageal echocardiography identified no more than mild regurgitation. There was no need for a second bypass run. There was no sign of left ventricular outflow tract obstruction or SAM. During 13.1 ± 6.8 months of follow-up, no patients died and no patient needed reoperation for recurrent mitral regurgitation. Mild mitral regurgitation occurred in five patients, and no patient had more than mild mitral regurgitation.
The mitral regurgitation caused by leaflet segment prolapse is characterized not only by chordal rupture or elongation but also commonly by leaflet enlargement with myxomatous changes. The pattern and degree of leaflet redundancy vary considerably from case to case. Current standard therapeutic options for posterior leaflet prolapse include quadrangular resection, triangular resection, and artificial chorda implantation without resection. SAM is an infrequent complication of standard methods of mitral valve repair, causing serious morbidities, which necessitate immediate surgical revision.5 SAM happens with anterior displacement of the leaflet coaptation line, which can be caused by repair leaving a relatively tall posterior leaflet or using a small annuloplasty ring.6 The butterfly resection achieves adjustable height reduction of the posterior leaflet segment by a similar mechanism to the sliding leaflet technique but without annular plication.
This operative design involves several advantages. First, the amount of leaflet resected in this method for the typical chronic degenerative posterior segment prolapse is smaller than in a classic quadrangular resection and is much smaller than that in the sliding leaflet technique. Second, as the conserved margins of leaflet are rotated toward the annulus, one can control the height of the new posterior leaflet as required, with minimal resection. We usually adjust the height of the new posterior segment to 10 to 15 mm. Third, the annular placation, which is required for quadrangular resection or sliding leaflet technique, is not needed for a butterfly resection.
A good indication for butterfly resection is a tall redundant posterior leaflet segment, typically with a height of >20 mm, commonly observed in chronic degenerative pathology. Although we have successfully used this technique for >60% of posterior leaflet prolapse cases in our current series, it may be contraindicated for short prolapsing lesions with no excess tissue. We simply use a small triangular resection for these shorter lesions or artificial chordate technique for wider, short lesions. We are aware that long-term durability needs to be followed. In conclusion, butterfly resection is a simple and effective technique for posterior leaflet prolapse repair of degenerative mitral valve disease, with acceptable early outcome.
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