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Updated: Sep 28, 2026

Closure of a Patent Foramen Ovale (PFO): An Intervention Sequence
Published on: December 23, 2022
Obstructive sleep apnea can be provocative for right-to-left shunting through a patent foramen ovale
Manolo Beelke1, Silvia Angeli, Massimo Del Sette
1Center of Sleep Medicine, DISMR, University of Genoa, Italy.
Study Objectives:
Under 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 Setting:
Assessment 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.
Participants:
10 consecutive patients affected by PFO detectable only under Valsalva maneuver during wakefulness and affected by OSAS (mean age 52.8 +/- 10.7 years).
Interventions:
Patients 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 Results:
Right-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).
Conclusions:
In 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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