Atrial septal defect in adult identical twins: a variation in theme.

The diagnosis of atrial septal defect was established in monozygotic twin females at age 63. Each patient mimicked a different acquired heart disease. One twin had congestive heart failure and atrial fibrillation and was diagnosed as having rheumatic mitral insufficiency. The other twin had atypical chest pain and systemic hypertension and was thought to have arteriosclerotic heart disease. In each case the correct diagnosis was made at cardiac catheterization. Although the same basic congenital heart lesion was present in both patients, the symptoms and findings differed. Symptomatic improvement was achieved by different therapeutic modalities. One patient had open heart surgery, while the other twin improved with medical therapy.