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Congenital Mitral Disease: Anomalous Mitral Arcade in a Young Man

2010; Elsevier BV; Volume: 89; Issue: 2 Linguagem: Inglês

10.1016/j.athoracsur.2009.07.070

1552-6259

Duccio Federici, Elisabetta Palmerini, Matteo Lisi, Luca Centola, Mario Chiavarelli, Sergio Mondillo,

Congenital Heart Disease Studies

We present the case of a 33-year-old man referred to our institution with a diagnosis of severe mitral valvular stenosis and insufficiency. We realized the valvular disease was due to an "anomalous mitral arcade," a rare congenital malformation of the mitral tensor apparatus characterized by enlarged papillary muscles connected to mitral leaflets by a typical fibrous tissue bridge. This arrangement creates a fibrous continuity between valvular and subvalvular apparatus. The reported echocardiographic images shows in detail the anatomic and functional features of this rare condition. We present the case of a 33-year-old man referred to our institution with a diagnosis of severe mitral valvular stenosis and insufficiency. We realized the valvular disease was due to an "anomalous mitral arcade," a rare congenital malformation of the mitral tensor apparatus characterized by enlarged papillary muscles connected to mitral leaflets by a typical fibrous tissue bridge. This arrangement creates a fibrous continuity between valvular and subvalvular apparatus. The reported echocardiographic images shows in detail the anatomic and functional features of this rare condition. Anomalous mitral arcade is a rare congenital malformation of the mitral valve and of its tensor apparatus that was first described by Layman Edwards [1Layman T.E. Edwards J.E. Anomalous mitral arcade: a type of congenital mitral insufficiency.Circulation. 1967; 35: 389-395Crossref PubMed Scopus (88) Google Scholar] in 1967. This anomaly is characterized by enlarged and elongated papillary muscles connected to each other and to the free edge of the anterior mitral leaflet by a bridge of fibrous tissue. The lack of interposition of chordae between the fibrous bridge and anterior leaflet creates a fibrous continuity that restricts valvular motion and prevents normal leaflets apposition. Generally, posterior leaflet chordae arise from the apices of papillary muscles. These may appear as few, short, and dysplastic; however, the posterior leaflet mobility is usually preserved. The natural history of the malformation is characterized by progressive worsening of valvular regurgitation or stenosis, or both. A patient who reaches adulthood usually undergoes mitral valve repair or replacement [2Castaneda A.R. Anderson R.C. Edwards J.E. Congenital mitral stenosis resulting from anomalous arcade and obstructing papillary muscles: report of correction by use of ball valve prosthesis.Am J Cardiol. 1969; 24: 237-240Abstract Full Text PDF PubMed Scopus (45) Google Scholar]. A 33-year-old man was admitted to our institution with evidence of effort dyspnea (New York Heart Association functional class II) and atrial fibrillation. We also appreciated an apical systolic murmur (grade 3/6) that had been casually diagnosed when the patient was 12 years old (grade 2/6). There was no history of tonsillitis or rheumatic fever. The first echocardiographic assessment was performed at the age of 20 when the patient was still asymptomatic, and posed the diagnosis of moderate mitral regurgitation associated with a mild grade of stenosis without evidence of rheumatic calcification. At the age of 32, an echocardiogram was repeated because of the onset of effort dyspnea. This study, performed in another institution, showed severe mitral regurgitation associated with moderate grade of stenosis. At admission to our institution 1 year later, the patient was in atrial fibrillation and was referred for worsening effort dyspnea. The echocardiographic evaluation performed in our department confirmed a severe mitral insufficiency with moderate valvular stenosis and left atrial enlargement without signs of rheumatic degeneration. The subvalvular mitral apparatus showed an "arc-like" configuration formed by enlarged papillary muscles and a characteristic fibrous tissue bridge connecting the muscles to each other and to the free edge of the anterior mitral leaflet (Fig 1). The posterior leaflet also showed a fibrous continuity with the fibrous bridge without interposition of chordae (Fig 2); this aspect represents a discordant feature from the usual manifestation of the anomaly. The resulting restriction in the motion of the anterior mitral leaflet caused severe valvular regurgitation by lack of coaptation and moderate degree of stenosis. Therefore, we made the diagnosis of anomalous mitral arcade.Fig 2Transthoracic apical 2-chamber view shows the direct fibrous tissue bridge (FB) continuity between the leaflets and the papillary muscles (P). (LA = left atrium; LV = left ventricle.)View Large Image Figure ViewerDownload (PPT) The patient was referred to the cardiac surgeon and underwent mitral valve repair after surgical confirmation of echocardiographic diagnosis. The repair consisted of posteromedial papillary splitting, interposition of 2 artificial polytetrafluoroethylene chordae (Gore-Tex, W. L. Gore and Associates, Flagstaff, AZ) at the P1 level after resection of an anterior papillary head and removal of fibrous tissue, and finally, application of complete mitral annuloplasty ring (Sovering No. 38, Sorin Biomedica, Italy). The procedure was successful. The patient's postoperative course was uneventful. An echocardiogram on postoperative day 4 showed normal mitral leaflets coaptation and no residual regurgitation (Fig 3). The patient was promptly discharged from the hospital with bisoprolol and warfarin therapy. Since the first description of this mitral anomaly in 1967, 14 cases have been reported. Most were detected when the patients were aged younger than 3 years. To date, only 3 adult patients have been described [3Kim S.J. Shin E.S. Park M.K. Choi S.H. Lee S.G. Congenital mitral insufficiency caused by anomalous mitral arcade in an elderly patient.Circ J. 2005; 69: 1560-1563Crossref PubMed Scopus (15) Google Scholar, 4Peretz J.A. Herzberg A.J. Reimer K.A. Bashore T.M. Congenital mitral insufficiency secondary to anomalous mitral arcade in an adult.Am Heart J. 1987; 114: 894-895Abstract Full Text PDF PubMed Scopus (15) Google Scholar, 5Myers M.L. Goldbach M.M. Sears G.A. Silver M.D. Anomalous mitral arcade: a rare cause of mitral valve disease in an adult.Can J Cardiol. 1987; 3: 60-62PubMed Google Scholar]. In this report we present a 33-year-old man in whom we evidenced the presence of an anomalous mitral arcade characterized by the typical arc-like configuration of subvalvular tensor apparatus causing restrictive motion of mitral leaflets. Of all reported cases to date, only 2 were diagnosed preoperatively by echocardiography; here we present a preoperative echocardiographic evaluation showing in detail the anatomic and functional characteristics of the anomaly. Therefore, echocardiography is a valuable tool for the diagnosis of this congenital malformation by virtue of its noninvasiveness and easy reproducibility. Echocardiography may also be helpful for the cardiac surgeon in planning the operation mainly for the choice of the best reparative technique. A careful echocardiographic evaluation of mitral leaflets structure is essential in diagnosis of anomalous mitral arcade. In fact, the lack of commissural fusion and calcific degeneration along with the subvalvular arc-like configuration enables the physicians to recognize this anomaly among other causes of mitral disease. In conclusion, in all cases of mitral stenosis or insufficiency, mainly in people who have not a history of rheumatic disease, it would be appropriate to consider the possibility of an anomaly in the development of the mitral arcade.