22/08/2026
This is a PFO. 🫧
A patent foramen ovale is a small flap-like opening between the two upper chambers of the heart. Everyone has it before birth. In most of us it seals over afterward. In roughly 1 in 4 people, it stays open. In everyday life, it's almost always harmless, and most people never know they have one.
So why do divers talk about it?
That little flap can let nitrogen bubbles slip from the right side of the heart to the left, skipping the lungs' natural filter and passing straight into your circulation. That's the link between a PFO and decompression sickness, and it's why it can show up after an "undeserved" hit that doesn't match your dive profile, inner-ear symptoms like vertigo, or a mottled rash after a dive.
It's not part of a standard dive medical. It's found with a bubble-contrast echo, often called a bubble study.
And here's the part that matters most: a diagnosis does not have to mean hanging up your fins. With a diving physician you have real options, from diving more conservatively to a catheter-based closure. Plenty of divers keep diving safely with the right plan. 💙
Educational only. Always speak with a diving physician.
