Right-to-left interatrial shunting with normal right ventricular pressure. A puzzling haemodynamic picture associated with some rare congenital malformations of the right ventricle and tricuspid valve.

Haemodynamic and angiographic findings are described in 5 cases with rare anomalies of the right ventricle and the second there was isolated congenital 'absence' of the tricuspid valve. The remaining 3 cases all had isolated congenital hypoplasia of the right ventricle; in 2 of these 3 cases closure of the atrial septal defect was successful in abolishing cyanosis and symptoms,while the third is awaiting surgical correction.