Patent foramen ovale and hypoxemia in chronic obstructive pulmonary disease.

In an obese 50 year-old heavy cigarette smoker with finger clubbing, persistent hypoxemia following an episode of right heart failure proved to be caused in part by a 12% right-to-left shunt through a patent foramen ovale. In this case report, we review the mechanisms of hypoxemia in patients with such a combination of diseases and suggest that the functional opening of a patent foramen ovale is likely to occur in some 25% of patients with right heart failure.