Mitral supravalvular ring: a case report
© Serra et al; licensee BioMed Central Ltd. 2005
Received: 17 May 2005
Accepted: 11 August 2005
Published: 11 August 2005
Supravalvular mitral stenosis is a rare condition characterized by an abnormal ridge, with one or two orifices, covering and obstructing the mitral valve. Preoperative diagnosis is difficult with transtoracic echo (TTE), angiography and magnetic resonance imaging (MRI).
In this case, a 36-year-old male, was admitted to our Heart department: He experienced progressive dyspnea on effort and at rest.
Diagnosis was made by transesophageal echocardiography which showed, on apical 4-chamber section, an anulare structure attached since a membrane to the atrial wall anterior mitral valve leaflet and just proximal to the posterior mitral leaflet.
Pre-operative identification of the supravalvular mitral ring is the target for obtaining good surgical results. Cineangiography and MRI both failed in reaching this objective, whereas, transesophageal echocardiography is the best method to identify this congenital heart disease.
Using TEE the identification is not only possible but also easier.
Keywordstransesophageal echocardiography mitral supravalvular ring
Mitral supravalvular ring is a rare congenital heart defect, as descibed by Fisher , characterized by an abnormal ridge of connective tissue on the atrial side of the mitral valve. Often the supravalvular ring may enroach on the orifice of the mitral valve leaflets and restrict their movements. While a supravalvular mitral ring may allow normal haemodynamic flow from the left atrium to the left ventricle, it often causes an obstruction of the mitral valve inflow . It can occur as an isolated defect, but in nearly 90% of the patients, the supravalvular ring is found in conjunction with other congenital heart defects . In the "Shone syndrome", it coexists with parachute mitral valvar, subvalvar aortic stenosis and aortic coartation. 
These two conditions have to be determined from the abnormal partition of the left atrium (cor triatriatum).
The supravalvular mitral ring is a ridge or membrane arising from the left atrial wall overlying the mitral valve and is sometimes attached to the mitral valve anulus, variable in thickness and extension it can range from being a thin membrane to a thick fibrous ridge. The membranous variety may be difficult to detect, since the membrane often adheres to the anterior mitral valve leaflet while remaining just proximal to the posterior mitral leaflets . In the same case, adhesion to the valve may impair opening movement of the leaflets, what's more, the ring may be large enough to protrude into the mitral valve inflow and cause obstruction. Sometimes, the ring may also be incomplete and eccentric, thereby, for an unobstructed flow through the mitral valve.
Chest x-ray showed left atrial and ventricular enlargement; alveolar edema in the hilar regions of both lung fields.
The echocardiogram (TTE) showed left ventricular enlargment, atrial dilatation, moderate/severe mitral regurgitation and moderate aortic regurgitation; mitral valve masses were suspected.
Based on this diagnosis, the patient underwent a transesophageal-echo (TEE).
Additional File 1: TEE showed, on apical 4-chamber section, an anulare structure attached like a membrane to the atrial wall anterior mitral valve leaflet and just proximal to the posterior mitral leaflet. This supravalvular ring was proximal to the left atrial appendage; a severe mitral regurgitation (IV grade PISA) and a mild diastolic gradient (6 mm/Hg DP mean) was detected by the Doppler-echocardiography. A moderate/severe aortic regurgitation was seen. (MPG 2 MB)
A moderate/severe aortic regurgitation was seen. Mitral vegetations were not identified. Coronary angiography was normal; left cineventriculography showed a severe aortic and mitral regurgitation, but a mitral supravalvular structure was not noticed.
Based on TEE diagnosis, the patient underwent surgery in November 2002.
A left atriotomy enabled the identification of a membrane right above the mitral valve with 2 small openings that allowed blood to flow from the atrium to the left ventricle. The membrane was excised and the mitral and aortic valves were replaced. Follow up: after 6 month, the patient was in I NYHA class. The transtoracic echo showed a normal function of prostesis.
Supravalvular mitral ring rarely occurs as an isolated defect, and other congenital heart defects coexist in most (90%) patients [5, 6]. The mitral valve itself is often abnormal and stenotic at the valvar or subvalvar level with fusion of leaflets, small valve orifice, and abnormal papillary muscle being common abnormalities. The Shone syndrome describes 4 congenital heart defects: mitral supravalvular ring, parachute mitral valve, subvalvar aortic stenosis and aortic coartation [7, 8].
Obstruction to mitral inflow comes from reduction in the mitral valve orifice area. When significant, a diastolic pressure difference occurs between the left atrium and left ventricle and this haemodinamic condition causes, in severe cases, pulmonary edema.
Other common associated lesions in patients with supravalvular mitral ring are ventricular septal defect and tetralogy of Fallot .
Even in the rarest cases, such as the case described above, its occurrence can be isolated, as first described by Chung .
Pre-operative identification of the membrane is possible by TEE [11, 12], where angiography often fails . However, there are still many limitations in visualization of the membrane, that is usually very thin; in this case, we performed an MRI examination, but as described in other papers [14, 15], there was a failure in the detection of the supravalvular mitral ring.
Pre-operative identification of the supravalvular mitral ring is the target for obtaining good surgical results. Cineangiography and MRI both failed in reaching this objective, whereas, TEE is the best method to identify this congenital heart disease. Using TEE the identification is not only possible but also easier.
New York Heart Association
Magnetic resonance imaging
- Fisher T: Two cases of congenital disease of the left side of the heart. Br Heart J. 1902, 1: 639-641.Google Scholar
- Lynch MF, Ryan NJ, William CR, Cayler G, Richardson WR, Campbell GS, Taybih : Preoperative diagnosis and surgical correction of supravalvular mitral stenosis and ventricular septal defect. Circulation. 1962, 25: 85-61.View ArticleGoogle Scholar
- Coto EO, Judez VM, Juffe A, Rufilanchas JJ, Tellez G, Maronas J, Aymerich DF: Supravalvular stenotic mitral ring. A new case with surgical correction. J Thorac Cardiovasc Surg. 1976, 71 (4): 537-539.PubMedGoogle Scholar
- Maron BJ, Edwards JE, Ferrans VJ, Clark CE, Lebowitz EA, Henry WL, Epstein SE: Congenital heart malformations associated with disproportionate ventricular septal thickening. Circulation. 1975, 52 (5): 926-932.View ArticlePubMedGoogle Scholar
- Mychaskiw G, Sachdev V, Braden DA, Heath BJ: Supramitral ring: an unusual cause of congenital mitral stenosis. Case series and review. J Cardiovasc Surg (Torino). 2002, 43 (2): 199-202.Google Scholar
- Abelson M: Parachute mitral valve and a large ventricular septal defect in an asymptomatic adult. Cardiovasc J S Afr. 2001, 12 (4): 212-214.PubMedGoogle Scholar
- Patel JJ, Ross JJ, Chandrasekaran K: A Form Fruste of Shone's Complex Diagnosed by Transesophageal Echocardiography. Echocardiography. 1996, 13 (2): 147-150.View ArticlePubMedGoogle Scholar
- Roche KJ, Genieser NB, Ambrosino MM, Henry GL: MR findings in Shone's complex of left heart obstructive lesions. Pediatr Radiol. 1998, 28 (11): 841-845. 10.1007/s002470050478. Review.View ArticlePubMedGoogle Scholar
- Watraida S, Shiraishi S, Katsuyama K, Nakajima Y, Onoe M, Sugita T, Yamamoto R, Imura M: Supravalvular stenotic mitral ring with ventricular septal defect. J Card Surg. 1997, 12 (1): 46-48.View ArticlePubMedGoogle Scholar
- Glaser J, Yakirevich V, Vidne BA: Preoperative echographic diagnosis of supravalvular stenosing ring of the left atrium. Am Heart J. 1984, 108 (1): 169-171. 10.1016/0002-8703(84)90563-5.View ArticlePubMedGoogle Scholar
- Oglietti J, Reul GJ, Leachman RD, Cooley DA: Supravalvular stenosing ring of the left atrium. Ann Thorac Surg. 1976, 21 (5): 421-424.View ArticlePubMedGoogle Scholar
- Roche KJ, Genieser NB, Ambrosino MM, Henry G: MR findings in Shone's complex of left heart obstructive lesions. Pediatr Radiol. 1998, 28 (11): 841-845. 10.1007/s002470050478.View ArticlePubMedGoogle Scholar
- Chung KJ, Manning JA, Lipchic EO, Gramiak R, Mahoney EB: Isolated supravalvular stenosing ring of the left atrium: diagnosis before operation and successful surgical treatment. Chest. 1974, 65: 25-28.View ArticlePubMedGoogle Scholar
- Moraes F, Lapa C, Ventura C, Santana R, Tenorio E, Moraes CR: Supravalvular congenital mitral stenosis. Arq Bras Cardiol. 2002, 79 (1): 79-84. 10.1590/S0066-782X2002001000008.View ArticlePubMedGoogle Scholar
- Roche KJ, Genesier Nancy B, Ambrosino Michael M, Henry Gilian L: MR finding in Shone's complex of left heart obstructive lesion. Pediatric Radiology. 1998, 28: 841-845. 10.1007/s002470050478.View ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.