Hypoxemia after implantation of a permanent pacemaker

We describe a case in which the patient developed profound, intermittent hypoxemia after implantation of a permanent pacemaker and subsequently after revision of its leads. Cardiac catheterization demonstrated right-to-left shunting at the level of the atria in the presence of a patent foramen ovale that required closure, resulting in the resolution of symptoms. Our report highlights the fact that the presence of a patent foramen ovale with intermittent right-to-left shunting should be considered in a differential diagnosis of hypoxemia after implantation of heart rhythm devices.