CPAP suppression of awake right-to-left shunting through patent foramen ovale in a patient with obstructive sleep apnoea.

The prevalence of an echocardiographically visible patent foramen ovale (PFO) is higher in patients with obstructive sleep apnoea syndrome (OSAS) than in normal controls. We report a patient who presented with OSAS and right-to-left shunting (RLS) through the PFO in whom the RLS disappeared after treatment for 1 week with nocturnal continuous positive airway pressure (CPAP). This case shows the role of OSA in generating an awake RLS through a PFO and its possible reversibility by CPAP. The mechanism of reversible awake RLS through PFO in OSAS is discussed.