People with a patent foramen ovale (PFO) may be at slightly greater risk of decompression sickness – a potentially fatal condition associated with scuba diving. Normally, gas bubbles travel through the veins during decompression. In individuals with a PFO, however, gas bubbles can travel from the right side of the heart to the left side and out to the rest of the body. When these gas bubbles travel through the arteries, they could cause a stroke or other life-threatening event. Research has shown that divers who have a PFO are more likely to have wounds or lesions in their brains.

To reduce the risk of serious health problems, divers who have a patent foramen ovale are encouraged to swim to the surface of the water slowly and not dive as deeply or as long as other divers. Depending on the size of the PFO, divers may also consider a procedure to have it closed. If they experience severe shortness of breath, they are encouraged to contact their physician right away.

German researchers have developed a fairly inexpensive test to help predict whether or not people are at risk before they dive. During the test, harmless bubbles are injected into a vein and then a painless ultrasound is performed to see if the bubbles are able to reach the brain. People who have a PFO should discuss the hazards of scuba diving with their physician before participating in diving activities.