Patent Foramen Ovale – PFO*)
PFO and Diving – My Journey from Diagnosis to Procedure
What is PFO?
PFO stands for Patent Foramen Ovale, which means an open hole in the atrial wall between the heart’s two upper chambers (atria). This hole exists naturally in fetuses but normally closes after birth. In about 25–30% of the population, it remains open, often without causing any symptoms. However, a PFO is considered to increase the risk of stroke.
PFO and Diving
For us divers, a PFO can pose an increased risk during pressure equalisation. If microbubbles of nitrogen after a dive take a shortcut through the PFO instead of being filtered by the lungs, they may reach the brain or other organs – which in rare cases can cause decompression sickness (DCS). Decompression sickness goes by many names – much like a beloved child has many names. Some of them include the bends, caisson disease (named after the pressurised work chambers used in underwater construction), and decompression illness.
Usually, the abbreviations DCS (Decompression Sickness) or DCI (Decompression Illness) are used.
DCS involves bubbles forming when dissolved nitrogen leaves tissues too quickly, forming bubbles that either don’t pass through the lungs or pass through a PFO instead of being exhaled. This can happen, for example, if one skips a safety stop or has insufficient decompression time, leading to common symptoms of decompression sickness such as:
Type 1 – Mild form
- Joint pain (especially in shoulders, arms, hips, and knees) – the most reported symptom.
- Fatigue or weakness
- Itching
- Rashes (e.g. bluish or mottled skin, especially on the torso or arms – sometimes called skin bends)
- Swelling of the skin or lymph nodes
- Pressure or aching around the affected area
- Numbness or tingling
- Paralysis or muscle weakness
- Balance issues or dizziness (vertigo)
- Coordination problems (ataxic gait)
- Visual disturbances (double vision, blurred vision)
- Headache
- Breathing difficulties or chest pain (may indicate lung involvement, e.g., “chokes”)
- Urinary retention or bowel disturbances
- Loss of consciousness or confusion
- Seizures
- Symptoms may appear immediately or with some delay – sometimes hours after surfacing. It is therefore crucial to seek hyperbaric treatment promptly when DCS is suspected.
DCI is an umbrella term covering two conditions: decompression sickness (DCS), caused by excess nitrogen dissolved in the body, and arterial gas embolism (AGE), which is caused by lung barotrauma from expanding gas. Both conditions may occur simultaneously.
AGE – considered the most dangerous consequence of too rapid ascent – arises when lung tissue ruptures. This can happen due to a faulty emergency ascent or anatomical/functional abnormalities in the lungs. Gas bubbles then enter the bloodstream and may cause a stroke or, in the worst case, death. Symptoms of AGE usually appear very quickly, often immediately after surfacing, frequently involving unconsciousness and seizures.
There are also two other types of AGE – these lead to subcutaneous or mediastinal emphysema, and pneumothorax. We won’t go into more detail here, but all of this is covered in diver training and is also explained in the PADI Encyclopaedia.
It should be noted that these conditions don’t only affect divers; they can also affect submariners, pilots, and astronauts.
My Story
I have been diving for many years and work as a diving instructor. In 2021, I visited the hyperbaric chamber here in Malta after a dive incident involving several contributing factors. After a brief treatment, I was discharged the same day. The symptoms were considered mild.
In Malta, a medical certificate is required to teach diving. Because of the 2021 incident, I was required to undergo an ultrasound to rule out PFO – a so-called bubble check. The visit to the hyperbaric chamber in 2021 was considered to increase the likelihood of me having a PFO, which later proved to be the case.
In January 2025, I underwent an ultrasound at Sophiahemmet in Stockholm. The result confirmed the presence of a mild PFO.
The short video shows the PFO, and the bubbles are the contrast fluid injected into the right atrium, which at the end of the film, leak into the left atrium. So I was among the one-third of the world’s population who “won the lottery”! 😁
The Procedure
After further examinations at Mater Dei Hospital, it was decided that a surgical procedure would be performed – a so-called PFO closure. The week before the procedure, I was prepared with blood tests and MRSA-preventive antibiotics.
On the day of the operation, I received intravenous antibiotics and was closely monitored. Everything was performed at the main public hospital here in Malta – Mater Dei Hospital.
The implant is an Amplatzer TorqVue2 PFO Closure Device from the company Abbott. As seen in the image, it is a double disc-shaped metal mesh structure that unfolds on both sides of the hole between the atria.
The short video first shows how the implant is guided into the atrium of the heart. A contrast agent is then injected, and colour is applied to ensure that the implant seals properly. In the coloured section of the film, one part of the implant is clearly visible.
During the procedure, the cardiac surgeon inserted a catheter device through the femoral vein into the heart and placed the closure implant to seal the unwanted PFO opening.
I went home with a supply of antibiotics and blood thinners in the form of aspirin – one tablet per day for at least six months.
Aspirin
Back in the day, many of us who practiced so-called technical diving took aspirin preventively before deep dives. The idea was that it facilitated nitrogen elimination from the body. Aspirin (acetylsalicylic acid) inhibits platelet aggregation, making the blood less prone to clot.
According to this older hypothesis, microbubbles in the blood after a dive could trigger local inflammation and clotting, and aspirin could thereby reduce the risk of DCS by improving blood flow and reducing the clotting response.
Results from the few older studies available from the 1970s and 1990s suggested a potential effect where aspirin or other NSAIDs (nonsteroidal anti-inflammatory drugs) could reduce microcirculatory impact and thus DCS symptoms. However, the results were not considered robust enough to recommend usage, and any potential benefit had to be weighed against the risk of bleeding.
We who took aspirin back then didn’t think much about the risks – hand on heart. That was then! Aspirin is not recommended as a prophylactic against DCS in modern dive medicine. Today, the focus is instead on:
- Optimised gas planning
- Conservative ascent profiles
- Proper hydration (i.e., avoid dehydration)
Follow-up and Future Diving
After six months, a final bubble check is to be done and, if all is well, a clean bill of health will be issued for instructors.
After undergoing a PFO closure, it’s natural to wonder when it’s safe to return to diving.
One common statement sometimes heard is that the heart “expands in size when diving,” and that this could affect the implanted closure device. But what does the science say?
When we dive, the body is subjected to increased pressure, and certain physiological changes occur:
- Venous return to the heart increases – more blood is pushed from the legs into the chest.
- Heart rate decreases (known as the “diving reflex”).
- Central blood volume pressure increases, meaning the heart’s chambers temporarily manage a larger blood volume.
However, this does not mean the heart expands in an abnormal or dangerous way. It stretches slightly – but well within the body’s normal regulatory capacity.
As for the metal PFO implant, new tissue will form over it during the first 3 to 6 months after the procedure. This secures the implant in place.
It is therefore essential to avoid sudden pressure changes during this period – especially in the first three months.
In theory, the implant could dislodge if the body is exposed to pressure changes before the implant has fully healed in place. But this is not because the heart “inflates” or physically pushes out the implant.
In other words, it’s absolutely essential to wait for the all-clear from a dive doctor (cardiologist) before resuming diving. Otherwise, the consequences could be quite serious.
At the end of August 2025, I underwent a bubble check and echocardiogram at Sophiahemmet in Stockholm. The PFO had reduced in size but had not completely closed. The examination revealed that a minor leakage remained. The cardiologist in Malta noted that six full months had not yet passed and that a new examination would be carried out in October 2025.
In early October 2025, a new bubble check was performed, and this time the “leak” was almost completely closed. The slightly elevated risk of DCI-related issues due to the PFO can be mitigated (not the same as completely avoided) by diving with enriched air (Nitrox), making an extra-long final stop before surfacing, and avoiding unnecessary overexertions. I hope to do a final bubble check within the next six months, and by then – hopefully – the PFO will be completely sealed.
I will not deny that these months without diving have been very frustrating. However, I have been swimming about three times per week and also doing strength training with my dumbells. On 8 September 2025, I could no longer resist the urge and went for a dive with a single tank and 38% oxygen (Nitrox), down to a maximum depth of 16 metres. The water was nearly 28°C and welcoming. It was a very calm and peaceful dive where I simply enjoyed being back in the water. A long 15-minute safety stop added safety to the experience. All the swimming and strength training also paid off – I felt much stronger both in my fin kicks and when climbing out of the water with full equipment after the dive. The experience, in all its simplicity, was truly memorable.
Disclaimer
*)This article is a translation from the original Swedish article. This English translation has not been translated by a certified translator. In the event of any discrepancies or inconsistencies between an English and a Swedish version, the Swedish text shall prevail.