[Right-to-left interatrial shunt with normal pulmonary pressures after pneumonectomy. Apropos of a case with severe cyanosis following left pneumonectomy].

Atrial septal defects usually give rise to left-to right in the absence of obstruction of the pulmonary outflow tract or pulmonary hypertension. The authors report a case of atrial septal defect with a right-to-left shunt despite normal pulmonary pressures at catheterisation in a 56 year-old-man who had undergone left pneumonectomy 6 months previously. The shunt was responsible for major arterial desaturation aggravated by the left lateral or dorsal decubitus position. Surgical closure of the defect resulted in cure with disappearance of cyanosis and normalisation of blood gases. The physiopathological mechanisms of these right-to-left shunts with normal pulmonary pressures are discussed with reference to previously reported cases in the literature.