Prevalence of patent foramen ovale in subjects with obstructive sleep apnea: a transcranial Doppler ultrasound study

Background: Under particular conditions a patent foramen ovale (PFO) can potentially give rise to ischemic stroke by means of paradoxic embolization. In obstructive sleep apnea syndrome (OSAS) right to left shunting (RLSh) can occur through PFO during periods of nocturnal apnea. Our study aimed to evaluate the prevalence of PFO diagnosed by means of transcranial Doppler (TcD) in subjects with OSAS. Methods: Seventy-eight consecutive subjects with OSAS (mean age 53±12 years) and 89 normal controls (mean age 48±9 years) underwent TcD with intravenous application of agitated physiological saline solution. The test was performed on patients at rest and during Valsalva maneuver. Results: PFO was present in 21 out of 78 patients with OSA (27%) and in 13 out of 89 control patients (15%). Seventeen out of 21 patients with OSA showed PFO only during Valsalva maneuver (85%) with respect to 12 out of 13 subjects of the control group (92%). Prevalence of PFO in OSAS was statistically different with respect to the control group ( P