Mitral atresia with normal aortic valve: a study of eighteen cases and a review of the literature.

Eighteen cases of mitral atresia with normal aortic valve plus 68 cases from the literature are analyzed. A new classification based on anatomical findings is proposed. Pulmonary stenosis or atresia is frequent in the type with transposition of the great arteries. The rare instances of normal or large left ventricle are due to a large ventricular septal defect, or to straddling or displaced tricuspid valve. The clinical, radiologic and electrocardiographic findings have been summarized and correlated with the different physiopathological situations. In our catheterized cases an oxygen saturation step-up was found in the right atrium together with left atrial hypertension. In seven cases mitral atresia was demonstrated by selective left atrial contrast injection. The average age at death was six months. Among the cases surviving one year or more, the association of atrial septal defects or pulmonary stenosis was frequent. Enlargement of the interatrial communication, accompanied by other palliative measures, is the only available surgical procedure.