The aim of this study is to determine whether catheter-based closure of patent foramen ovale (PFO) is effective in preventing paradoxical embolization of nitrogen bubbles after simulated dives.~Ultrasonographic detection of venous and arterial nitrogen bubbles will be performed in divers after surfacing from simulated dives in hyperbaric chambers. Divers will be observed after two different dive profiles - Dive A (dive to 18 m for 80 min bottom time) and dive B (dive to 50 m for 20 min bottom time), both performed according to US Navy Air decompression procedure 1996. For both dives two groups will be compared: Divers with PFO and divers after previous catheter-based closure of PFO.~The study will be observational. Sonographic detection of bubbles will be performed after simulated dives that are part of a training program of the divers. Two different dives, previously documented to generate significant amount of venous nitrogen bubbles, were chosen.~The primary end-point will be a positive transcranial doppler test (defined as one or more bubbles detected either during native breathing or after Valsalva maneuver).~Inclusion criteria are: 1) previously diagnosed PFO or a PFO that has been occluded by a catheter-based procedure, 2) signed informed consent~Exclusion criteria: 1) another dive performed in the preceding 24 hours, 2) another previously diagnosed right-to-left shunt, 3) disagreement to be included in the study~This study will be single-center.
The aim of this study is to determine whether catheter-based closure of patent foramen ovale is effective in preventing paradoxical embolization of nitrogen bubbles after simulated dives.