Patent Foramen Ovale (PFO) is a topic of perennial interest to divers — DAN Medical Services fields dozens of PFO-related calls every year. This is understandable; the heart is a complex and critically important organ, and more than a quarter of all adults have a PFO. With uncertainty about the condition’s implications and divers’ desire to minimize risk in the water, some amount of consternation is entirely reasonable. Take a moment to improve your understanding of the condition, and learn how it could affect your 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 fetuses 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. 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 the condition. 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 minimize their risk through behavioral 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. In the course of the test, the patients will be asked to sniff or perform a Valsalva maneuver 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 are 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. If you experience serious neurological DCI or repeated instances of cutaneous decompression sickness, however, discuss your options with a qualified physician.
For more information about PFOs, visit DAN.org/Health