Diving with Patent Foramen Ovale (PFO)

Patent Foramen Ovale (PFO) is a topic of constant interest to divers - DAN Medical Services field dozens of PFO-related calls every year.

This is understandable as the heart is a complex and critically important organ and more than a quarter of all adults have a PFO.
But given the uncertainty about the condition’s implications, and divers’ desire to minimise risk in the water, some amount of consternation is entirely reasonable.

For dive professionals who experience greater frequency of exposure to decompression stress and who may rely on their fitness to dive to make a living, it’s especially important to understand how a PFO could affect their work and health. So take a moment to improve your understanding of PFO and learn how it could affect your risks, and your students’ risks, while diving.

What is a PFO?

A PFO is an opening in the wall separating the upper chambers of the heart, the left and right atria. The opening is a remnant of a flap valve present in developing foetuses that shunts oxygenated blood from the mother directly from one atrium to the other. In most cases this flap closes permanently after birth, but in as many as 27% of adults this flap never shuts completely. The defect is relatively benign and rarely detected and it typically poses little or no risk to otherwise healthy adults in the normal course of life.

What are the risks?

Complications from a PFO are rare in otherwise healthy adults. Most people with a PFO will never be diagnosed with, or experience complications from it. For divers, however, PFOs can present problems because of the inert-gas bubbles that arise following dives. Gas bubbles that occur in venous blood after a dive can potentially pass through a PFO of adequate size and bypass the pulmonary filter (the lungs), which may cause decompression illness (DCI).

This hazard is the source of much of the concern surrounding PFOs, but people with a PFO can minimise their risk through behavioural or surgical modification.
Practical risk-management strategies for cardiac defects exist but each case is unique. If you are diagnosed with a PFO, your physician will help you determine the best course of action and risk-management practices.
Should I get tested for a PFO?

PFOs are typically identified by injecting a small quantity of bubbles into a vein and monitoring the bubbles’ travel through the heart using contrast echocardiography. During the test, the patients will be asked to sniff or perform a Valsalva manoeuvre to attempt to open a PFO, should one exist, and allow blood to travel directly from the right to the left atrium.

There are a few ways this test can be performed, but all are invasive and not considered the first step in managing a potential PFO, particularly if you have never had DCI.
For most divers, it is not worth the risk or expense to get tested for a PFO. Many divers with a PFO will never experience DCI, let alone DCI that might have resulted from bubbles shunted through a PFO. However, if you experience serious neurological DCI or repeated instances of cutaneous decompression sickness, discuss your options with a qualified physician.

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