Cyanosis following right pneumonectomy: importance of patent foramen ovale.

A patient with chronic lung disease became cyanotic following right pneumonectomy for cancer. He was found to have right-to-left shunting through a patent foramen ovale in the absence of pulmonary hypertension, and he improved remarkable after surgical therapy. This case vividly illustrates the subtlety with which acquired right-to-left shunting may appear in the setting of chronic hypoxemia. The frequency of patent foramen ovale in the general population (20 percent) and the ease and efficacy of treatment for this lesion underscore the need for general awareness of this potential problem in the chronically or critically ill.