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We congratulate Sarioğlu and colleagues [1Sarioğlu T. Arnaz A. Saygili A. Accessory miniature mitral valve causing subaortic obstruction (letter).Ann Thorac Surg. 2015; 99: 1868-1869Abstract Full Text Full Text PDF Scopus (2) Google Scholar] for their successfully managed case of an accessory miniature mitral valve (AMMV) causing left ventricle outflow tract obstruction (LVOTO) in a 4-year-old child. Congenital malformations of the mitral valve are rare, often complex, and affect multiple segments of the valve apparatus. They occur in isolation or in association with other congenital heart defects. Accessory mitral valve tissue (AMVT) is an extremely rare anomaly of the mitral valve, first reported by MacLean who described the first surgical resection of an accessory mitral valve leaflet in 1963. Since then, there have been an increasing number of reports, enough for a classification to be proposed by Prifti and colleagues [2Prifti E. Bonacchi M. Bartolozzi F. Frati G. Leacche M. Vanini V. Postoperative outcome in patients with accessory mitral valve tissue.Med Sci Monit. 2003; 9: RA126-RA133PubMed Google Scholar] on the basis of its intraoperative description; type-I defined as a fixed mass, nodular (type IA), or membranous (type IB). Type II occurs as a mobile mass, pedunculated (type IIA), or leaflet-type (type IIB). Type IIB is further divided into those with rudimentary chordae tendineae (type IIB1) or well-developed chordae tendineae (type IIB2). An AMVT can be an incidental echo finding or more commonly presents with symptoms of LVOTO. Complications include systemic embolization, arrhythmias, endocarditis, aortic or mitral valve dysfunction. Echocardiography is the gold standard diagnostic modality; three-dimensional echocardiography and cardiac magnetic resonance imaging can better delineate the anatomy of an AMVT. Indication for surgery is debatable, particularly in asymptomatic patients without other cardiac lesions; however, the indication can be diagnosis to prevent serious complications. Surgery involves resecting the AMVT while preserving functional mitral and aortic valves without any residual LVOTO. A transaortic approach provides an excellent access [3El-Eshmawi A. Castillo J.G. Rhee A.J. Pawale A. Anyanwu A.C. Accessory mitral valve leaflet.Ann Thorac Surg. 2014; 98: 344Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar]. Alternative approaches include left atriotomy, systemic ventriculotomy in small infants, and resection through an associated ventricular septal defect. Prognosis of AMVT is generally benign; however, prognosis can be guarded if prosthetic valve replacement is required. The case report presented by Sarioglu and colleagues represents a supernumerary complete duplicate mitral valve apparatus with 2 separate leaflets, papillary muscles, and chordal sets that make it unique from other case reports of accessory mitral leaflet. Future reports should allow us to better define the anatomic subtypes of such an extremely rare mitral valve anomaly. Accessory Miniature Mitral Valve Causing Subaortic ObstructionThe Annals of Thoracic SurgeryVol. 99Issue 5PreviewWe have read the article by Ahmed El-Eshmawi and colleagues [1] titled “Accessory mitral valve leaflet” with great interest. Accessory mitral tissue is one of the rare lesions that may cause left ventricular outflow tract obstruction (LVOTO). We have seen an extremely rare lesion an “accessory miniature mitral valve” leading to severe obstruction at the left ventricular outflow tract (LVOT) in a 4-year-old boy (Fig 1A). This accessory miniature mitral valve had two separate leaflets, chordae, and papillary muscles (Fig 1C). Full-Text PDF