• Manolo Beelke, Silvia Angeli, Massimo Del Sette, Fabrizio De Carli, Paola Canovaro, Lino Nobili, and Franco Ferrillo.
• Center of Sleep Medicine, DISMR, University of Genoa, Italy.
• Sleep. 2002 Dec 1;25(8):856-62.

Study ObjectivesUnder particular conditions, a patent foramen ovale (PFO) can potentially give rise to ischemic stroke by means of paradoxical embolization, due to right-to-left shunt. Our study aimed to evaluate the presence of right-to-left shunt in patients with obstructive sleep apnea syndrome (OSAS) and diagnosed PFO during sleep.Design And SettingAssessment of provocative-only PFO and concomitant OSAS. Evaluation of right-to-left shunting during sleep by means of transcranial doppler with contrast medium injected in the cubital vein.Participants10 consecutive patients affected by PFO detectable only under Valsalva maneuver during wakefulness and affected by OSAS (mean age 52.8 +/- 10.7 years).InterventionsPatients underwent transcranial doppler with injection of agitated saline solution mixed with air during normal breathing and during periods of apnea/hypopnea in nocturnal sleep.Measurements And ResultsRight-to-left shunt was present in 9 patients out of 10 and appeared during obstructive apneas longer than 17 seconds. In 1 out of 10 patients, only hypopneas occurred and no right-to-left shunt could be shown. The number of microembolic signals detected during periods of nocturnal apnea was positively correlated with the number detected during Valsalva maneuver in wakefulness (p<0.0001).ConclusionsIn the nocturnal sleep period, right-to-left shunt can occur during single obstructive apneas in patients with OSAS and concomitant presence of PFO. This can be a risk factor for cerebrovascular diseases. This risk could probably increase proportionally to the respiratory disturbance index of these patients.

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