Case Report TGA patients, Hazekemp et al.8 observed that mitral valve anomalies prevented LVOT obstruction relief, permitting either Senning or univentricular palliation. The possible rea- sons in this patient may be either the AMVT may have been overlooked or prevented LVOT obstruction relief, or it did not produce signifi- cant obstruction at that time. The reason for such severe LVOT gradient now may be pro- gressive thickening of the tissue over the years or development of fibro-muscular hyper- trophy of LVOT, as noted by some authors.4,5 At the current time, even though transthoracic echocardiography is sufficient to visualize AMVT, addition of transesophageal echocardio- graphy and three-dimensional echocardiogra- phy may further delineate the structure pre- cisely. Due to their susceptibility to neurologi- cal events, patients with AMVT are advised to take aspirin prophylaxis.7 In conclusion, AMVT should be considered in the differential diag- nosis of LVOT obstruction, specifically in pre- and post-operative congenital heart disease patients. References 1. Rovner A, Thanigaraj S, Perez JE. Accessory mitral valve in an adult popula- tion: the role of echocardiography in diag- nosis and management. J Am Soc Echo- cardiogr 2005;18:494-8. 2. Prifti E, Bonacchi M, Bartolozzi F, et al. Postoperative outcome in patients with accessory mitral valve tissue. Med Sci Monit 2003;9:126-33. 3. Prifti E, Frati G, Bonacchi M, et al. Accessory mitral valve tissue causing left ventricular outflow tract obstruction: case reports and literature review. J Heart Valve Dis 2001;10:774-8. 4. Yoshimura N, Yamaguchi M, Oshima Y, et al. Clinical and pathological features of accessory valve tissue. Ann Thorac Surg 2000;69:1205-8. 5. Uslu N, Gorgulu S, Yildirim A, Eren M. Accessory mitral valve tissue: report of two asymptomatic cases. Cardiology 2006;105: 155-7. 6. Popescu BA, Ghiorghiu I, Apetrei E, Ginghina C. Subaortic stenosis produced by an accessory mitral valve: the role of echocardiography. Echocardiography 2005; 22:39-41. 7. Yuan SM, Shinfeld A, Mishaly D, et al. Accessory mitral valve tissue: a case report and an updated review of literature. J Card Surg 2008;23:769-72. 8. Hazekamp M, Portela F, Bartelings M. The optimal procedure for the great arteries and left ventricular outflow tract obstruc- tion. An anatomical study. Eur J Cardio- thorac Surg 2007;31:879-87. 9. Sohn YS, Brizard CP, Cochrane AD, et al. Arterial switch in hearts with left ventricu- lar outflow and pulmonary valve abnormal- ities. Ann Thorac Surg 1998;66:842-8. 10. Hazekamp MG, Gomez AA, Koolbergen DR, et al. European Congenital Heart Surgeons Association. Surgery for transposition of the great arteries, ventricular septal defect and left ventricular outflow tract obstruc- tion: European Congenital Heart Surgeons Association multicentre study. Eur J Cardiothorac Surg 2010;38:699-706. [page 20] [Heart International 2011; 6:e6]