Nitrogen Bubble Detection After Simulated Dives in Divers With PFO and After PFO Closure

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Nitrogen Bubble Detection After Simulated Dives in Divers With PFO and After PFO Closure

Conditions
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Patent Foramen Ovale

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: previously diagnosed PFO or a PFO that has been occluded by a catheter-based procedure signed informed consent Exclusion criteria: another dive performed in the preceding 24 hours another previously diagnosed right-to-left shunt disagreement to be included in the study

Ages Eligible for Study
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Minimum Age: 19 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patent foramen ovale dive A group<br>Divers with a previously diagnosed patent foramen ovale observed after Dive A. | |
| Closure dive A group<br>Divers with a patent foramen ovale previously closed by a catheter-based procedure observed after Dive A. | |
| patent foramen ovale dive B group<br>Divers with a previously diagnosed patent foramen ovale observed after Dive B. | |
| closure dive B group<br>Divers with a patent foramen ovale previously closed by a catheter-based procedure observed after Dive B. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arterial Nitrogen Bubbles After Surfacing | Arterial gas bubbles are detected by transcranial doppler ultrasonography. Positive outcome is 1 or more bubbles detected. | assesed within 1 hour after surfacing | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Patent foramen ovale, Catheter-based closure, Nitrogen bubbles, Decompression sickness