We report the case of a newborn baby with an unguarded mitral orifice associated with asplenia syndrome, double-outlet right ventricle, dysplastic tricuspid valve, and pulmonary stenosis. This case was accompanied by severe tricuspid regurgitation and severe right ventricular hypertrophy. The patient had a fatal clinical course due to severe hypoxia and congestive heart failure. Unguarded mitral orifice is a rare disease in which there has been no previous report of lethal clinical course during the neonatal period. Prior reports stated that unguarded mitral orifice was a new constellation of defects and that its etiology and embryology could be classified in the same category because of similar associated malformations of double-outlet right ventricle and pulmonary stenosis or atresia. However, the present case was diagnosed on autopsy as also having asplenia syndrome. Therefore, it is possible that the genetic etiology of unguarded mitral orifice in this case was different from cases of non-heterotaxy. <Learning objective: Unguarded mitral orifice is a rare disease that might be associated with asplenia syndrome and dysplastic tricuspid valve. If unguarded mitral orifice is associated with such defects, the clinical course can be fatal. Therefore, when this diagnosis is recognized, the physician should explain the possibility of neonatal death and plan the treatment of such a case to include grief therapy for the family.>.
Keywords: Asplenia syndrome; Atrioventricular valve regurgitation; Double outlet right ventricle; Dysplastic tricuspid valve; Unguarded mitral orifice.