Ann Thorac Surg 2006;82:1103-1106
© 2006 The Society of Thoracic Surgeons
Case report
Partial Hammock Valve: Surgical Repair in Adulthood
José I. Aramendi, MDa,*,
Miguel A. Rodríguez, MDa,
Roberto Voces, MDa,
Pedro Pérez, MDb,
David Rodrigo, MDb
a Division of Cardiac Surgery, Hospital de Cruces, Barakaldo, Vizcaya, Spain
b Division of Cardiology, Hospital de Cruces, Barakaldo, Vizcaya, Spain
Accepted for publication December 20, 2005.
* Address correspondence to Dr Aramendi, Division of Cardiac Surgery, Hospital de Cruces, Plaza de Cruces, Barakaldo, Vizcaya, 48903 Spain (Email: jiaramendi{at}hcru.osakidetza.net).
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Abstract
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We describe a forme frustrée of hammock valve involving only the posterior mitral leaflet. Three adult patients were referred to surgery with the diagnosis of severe mitral regurgitation due to fibrosis of the posterior mitral leaflet. The final diagnosis was done intraoperatively. In all of them the posterior leaflet was attached to some accessory papillary muscles arranged en palisade, with three to four fused muscle heads producing restrictive leaflet motion in systole. Repair consisted in division of the papillary muscles, patch augmentation, and ring annuloplasty. This previously unreported lesion is congenital but manifests itself in adulthood.
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Introduction
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Hammock mitral valve is a rare congenital malformation resulting in mitral stenosis or regurgitation, or both. The main feature is the presence of a huge unique posterior papillary muscle that gives short chordae to both mitral leaflets mimicking the shape of a hammock. In this report we describe a forme frustrée of hammock valve involving only the posterior mitral leaflet.
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Case Report
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Three adult patients were referred to surgery with the diagnosis of severe mitral regurgitation due to fibrosis of the posterior mitral leaflet. The patients were scheduled for standard mitral valve repair surgery. Therefore no institutional review board protocol was deemed necessary. An informed consent was obtained from all patients. The final diagnosis was done intraoperatively.
Patient 1
A 58-year-old woman was diagnosed with severe mitral regurgitation due to fibrosis of the central portion of the posterior mitral leaflet. She was in New York Heart Association functional class III. She was operated on in October 1995. Surgical findings were that the anterior mitral leaflet was normal with chordae arising from two normal looking heads of the anterior and posterior papillary muscles. The papillary muscles corresponding to the posterior mitral leaflet consisted of three muscle heads fused together and aligned en palisade, each giving chordae to P1, P2, and P3. The central chordae were short and fibrosed resulting in restricted motion in systole. Repair consisted in splitting the three heads longitudinally, a section of secondary chordae, and implantation of a rigid size 32 Carpentier ring (Edwards Lifesciences, Irvine, CA). The postoperative course was uneventful. In the 10-year follow-up, echocardiogram revealed a normal sized left ventricle with an ejection fraction of 62%, grade I/IV regurgitation, and a pulmonary pressure of 32 mm Hg.
Patient 2
A 61-year-old woman was referred to surgery with the diagnosis of severe mitral regurgitation due to fibrosis of the posterior leaflet. She was in New York Heart Association functional class II with severe pulmonary hypertension. During the operation, in May 2004, three fused heads of papillary muscles giving chordae to the posterior leaflet were found. After longitudinal division of the heads there was a residual restrictive leaflet motion of P2. Leaflet augmentation of P2 and P3 with a semilunar patch of bovine pericardium was performed. A size 32 Carpentier Physioring (Edwards Lifesciences) was implanted. The postoperative course was uneventful. In the follow-up, 1 year postoperatively, grade I/IV residual regurgitation was found; mitral valve area was 2 cm2.
Patient 3
A 74-year-old man was diagnosed with severe mitral regurgitation due to fibrosis of the posterior mitral leaflet (Fig 1). He was in New York Heart Association functional class III with severe pulmonary hypertension. He was operated upon in July 2004. His anterior mitral leaflet was normal. There was a palisade of four papillary muscles giving chordae to the posterior leaflet (Fig 2). There was a restrictive leaflet motion of P2. Patch augmentation was made with bovine pericardium and a size 32 Carpentier Physioring (Edwards Lifesciences) was implanted. In the follow-up, 1 year after surgery, grade I/IV residual mitral regurgitation was found. His left ventricle ejection fraction was 55%, and his pulmonary hypertension was reduced to 41 mm Hg.
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Fig 1. Two-dimensional echocardiogram. (A) Apical four-chamber view. Right, diastole: normal opening of the mitral valve. Left, systole: restrictive leaflet motion of P2 with fibrosis of chordae; severe mitral regurgitation by color-Doppler. (B) Apical two-chamber view. Right, diastole: thickening and fibrosis of P2 and its chordae. Left, systole: restrictive leaflet motion of P2.
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Fig 2. (A) Surgical view. Note the four fused muscle heads to the posterior leaflet. The arrow shows fibrosis of P2. (B) Two-dimensional echocardiogram apical two-chamber view. The arrow shows that a fibrotic accessory muscle head to P2 can be suspected.
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Comment
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Stellin and colleagues [1] proposed the terms mitral valve dysplasia as a malformation that includes a wide spectrum of congenital morphologic abnormalities that affect the mitral valve resulting in stenosis or regurgitation, or both. This term may be helpful in order to facilitate a homogeneous presentation of the results among groups, but it is ambiguous as it includes different anatomic lesions that have different outcomes and possibilities of surgical repair. The true hammock valve is one of the most difficult mitral lesions to repair, and in most instances a valvular prosthesis must be implanted [2]. Surgery is almost always required in infancy, although 1 patient reached adulthood without surgery [3]. We believe that the lesion that we describe has not been published before now. We call it a partial hammock valve because the chordal attachments of the posterior leaflet resemble the true hammock valve. We could also call it a palisade posterior mitral valve because of the special arrangement of the accessory papillary muscles forming a palisade. Rosenquist and colleagues [4] published a similar presentation of accessory papillary muscles in specimens of transposition of the great arteries, but so far, this has not been found as an isolated lesion until now. The hemodynamic lesion consists of Carpentier type III (Edwards Lifesciences) regurgitation (restricted leaflet motion in systole). The fact that the anterior leaflet is not affected explains the rather benign course of the disease. Initially the restricted leaflet motion is mild and there is sufficient surface of coaptation. With time, chordal fibrosis and shortening occurs, resulting in lack of coaptation of P2 and subsequent annular dilatation further increases the degree of regurgitation. We have been applying the technique of patch augmentation for other typical forms of restricted leaflet motion, as in ischemic mitral regurgitation with excellent results [5]. We find this technique quite reproducible and it can be applied to any situation in which restrictive leaflet motion is present. Even though the suspicion of mitral regurgitation of congenital origin could be aroused by the echocardiographic findings, the final diagnosis was done during the operation. Present two-dimensional echocardiographic techniques cannot properly identify the arrangement of the papillary muscles. The next generation of three-dimensional echocardiograms may give a better definition of the subvalvular apparatus [6]. The prevalence of this lesion is very rare. We could identify only 3 patients in 10 years. We suspect that this lesion may have been overlooked by others and was probably considered a rare form of degenerative mitral regurgitation.
In conclusion, the presence of mitral regurgitation due to restrictive motion of the posterior leaflet may be congenital. We report a new type of congenital mitral lesion consisting of accessory papillary muscles en palisade that presents itself in adulthood.
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References
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- Stellin G, Padalino M, Milanesi O, et al. Repair of congenital mitral valve dysplasia in infants and childrenis it always posible?. Eur J Cardiothorac Surg 2000;18:74-82.[Abstract/Free Full Text]
- Layman T, Edwards JE. Anomalous mitral arcade Circualtion 1967;35:389-395.[Abstract/Free Full Text]
- Zegdi R, Khabbaz Z, Chavaud S, Garçon P, Carpentier A, Deloche A. Functional classification dictates type of repair in "complex" mitral insufficiencyapplication to a case of a hammock mitral vale in an adult patient. J Thorac Cardiovasc Surg 2005;130:217-218.[Free Full Text]
- Rosenquist GC, Stark J, Taylor JFN. Congenital mitral valve disease in transposition of the great arteries Circulation 1975;51:731-737.[Abstract/Free Full Text]
- Rendón F, Aramendi JI, Rodrigo D, Baraldi C, Martínez P. Patch enlargement of the posterior mitral leaflet in ischemic regurgitation Asian Cardiovasc Thorac Ann 2002;10:248-250.[Abstract/Free Full Text]
- Barrea C, Levasseur S, Roman K, et al. Three-dimensional echocardiography improves the understanding of left atrioventricular valve morphology and function in atrioventricular septal defects undergoing patch augmentation J Thorac Cardiovasc Surg 2005;129(4):746-753.[Abstract/Free Full Text]
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Abstract
Introduction
