[Patent foramen ovale: an underrated risk for divers?]

The foramen ovale which is the fetal connection between the right and left atrium persists in about 30 % of the adult population. In the presence of a persistent foramen ovale (PFO) shunting of blood may occur from the right to the left atrium, and bubbles can reach the systemic circulation during or after the decompression phase of a dive with compressed air. Therefore, divers with PFO may have an increased risk to develop ischemic cerebral lesions and neurologic decompression sickness (DCS). Significant right-to-left shunting may be diagnosed using transcranial doppler ultrasound of the medial cerebral artery and echocardiography with echo contrast media and Valsalva provocation. However, there are no official guidelines concerning PFO screening in medical fitness exams for professional or recreational divers in Germany. Therefore, it remains in the diver's choice to be screened for PFO. Divers with a history of DCS should be monitored for PFO, especially when diving strictly adhered to decompression tables. Divers with PFO who refuse to stop diving after DCS should be advised to adhere to very save dive profiles.