[Paradoxical embolization and patent foramen ovale in scuba divers: screening possibilities]

The cause of decompression sickness (DCS) in scuba-divers is bubble formation in tissues and in venous blood during ascent. Divers with patent foramen ovale (PFO) have an increased risk of paradoxical embolization to the brain or other vital organs. The aim of our study was to assess the incidence of PFO in scuba-divers with DCS, to compare the group with asymptomatic controls, and to evaluate ultrasound contrast methods suitable for screening.

We examined 28 scuba-divers (more than 100 dives). The right-to-left shunt detection was performed by bubble contrast transthoracic echocardiographic examination (TTE) and transcranial Doppler sonography over arteria cerebri media (TCD) in all divers. In divers with shunting, transoesophageal echocardiography (TEE) was performed to prove PFO.

15 divers had DCS associated with the ascent. In this group, PFO was diagnosed in 53% (8/15). The symptoms of all of them retrospectively were of paradoxical embolization (neurological form of DCS). In the group of asymptomatic divers, PFO was proven on the basis of right-to-left shunt screening in 1 diver (8% 1/13). TCD proved right-to-left shunt in all divers with PFO.

DCS can unmask a so far asymptomatic intracardiac right-to-left shunting. PFO is a risk factor for paradoxical embolization in divers. TCD is suitable for screening; TEE is a gold standard in PFO detection. Our results showed that PFO detection is a useful clinical tool after repeated DCS and in all frequent divers and instructors.