title: The role of persistent foramen ovale and other shunts in decompression illness.
abstract: A persistent foramen ovale (PFO) and other types of right-to-left shunts are associated with neurological, cutaneous and cardiovascular decompression illness (DCI). A right-to-left shunt is particularly likely to be implicated in causation when these types of DCI occur after dives that are not provocative. It is believed that venous nitrogen bubbles that form after decompression pass through the shunt to circumvent the lung ﬁlter and invade systemic tissues supersaturated with nitrogen (or other inert gas) and as a result there is peripheral ampliﬁcation of bubble emboli in those tissues. Approximately a quarter of the population have a PFO, but only a small proportion of the population with the largest right-to-left shunts are at high risk of shunt-mediated DCI. The increased risk of DCI in people with migraine with aura is because migraine with aura is also associated with right-to-left shunts and this increased risk of DCI appears to be conﬁ ned to those with a large PFO or other large shunt. Various ultrasound techniques can be used to detect and assess the size of right-to-left shunts by imaging the appearance of bubble contrast in the systemic circulation after intravenous injection. In divers with a history of shunt-mediated DCI, methods to reduce the risk of recurrence include cessation of diving, modiﬁcation of future dives to prevent venous bubble liberation and transcatheter closure of a PFO.
authors.affiliation: Dr Wilmshurst was Guest Speaker at the SPUMS Annual Scientiﬁ c Meeting, Bali, May 2014, Consultant Cardiologist, Royal Stoke University Hospital, Stoke-on-Trent ST4 6QG, UK, E-mail: peter.wilmshurst@tiscali.co.uk, Phone: +44-(0)1782-675982.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Wilmshurst
mesh_terms: D003664:Decompression / Q000009:adverse effects; D003665:Decompression Sickness / Q000209:etiology*; D054092:Foramen Ovale, Patent / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D006344:Heart Septal Defects, Atrial / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D020325:Migraine with Aura / Q000150:complications; D009929:Organ Size; D012307:Risk Factors; D012871:Skin Diseases / Q000209:etiology; D014463:Ultrasonography
keywords: Right-to-left shunt; arterial gas embolism; bubbles; decompression illness; percutaneous closure; review article; persistent foramen ovale (PFO)