Patent Foramen Ovale
If you’ve been diving a while and have any interest in diving physiology you’ve probably at some point heard the term PFO. But what is it and how exactly does it affect diving? A PFO, or Patent Foramen Ovale, is a common congenital heart defect. About a quarter of the population has one and most never know, as it generally doesn’t affect most people. But what is it?
When we’re in the womb, we have a hole in our hearts called a foramen ovale. This hole allows blood to pass between the left and right atria, as we cannot breathe yet. Once we’re born and start to breathe, the hole is supposed to close. When it doesn’t completely seal shut it becomes a patent foramen ovale. As previously said, this doesn’t affect most people and most never know they have one. The issue occurs when something that is supposed to be filtered out of our blood stream via our lungs doesn’t filter, like a blood clot, or - relevant to divers - a gas bubble.
An average person will not get diagnosed with a PFO. They generally only get diagnosed if they start causing issues. In most people the issues show up as severe migraines or strokes. It has been found that 40% – 50% of people who have a stroke from unknown causes have a PFO as well. For divers, issues show up as neurological and cutaneous (skin) decompression illness (DCI). People with PFOs are 2.5 times more likely to get DCI, and 4 times more likely to get neurological DCI.
Now this being said, the important thing to note is although the risk of getting DCI is increased, it is still low. The risk is so low that it is not necessary to include PFO testing into a routine dive medical evaluation. Many divers with PFOs go their entire diving career without ever having DCI or any reason to suspect a PFO. Occasionally there are people who get undeserved DCI hits and a PFO may then be something to look into.
If your doctor agrees that a PFO may be present, you’ll need testing to confirm. If a PFO is confirmed, you have three options: stop diving, dive more conservatively, or get it shut. All these options have positives and negatives and would call for a serious talk with your doctor. Getting a PFO shut generally no longer involves open heart surgery, but it is still a surgery that involves risks.
Over the summer I had some intestinal surgery, and while the doctors were checking to make sure I was healthy post-surgery, they did two echocardiograms. One showed I had a PFO, and one did not. A neurologist called me to let me know and started off by explaining about blood flow and heart function and the hole we have as newborns. I interrupted him asking if he was talking about a PFO. He seemed surprised I knew what it was, but said yes, and skipped explaining what it was and started talking about how they generally aren’t an issue so we didn’t need to do further testing. Again, I interrupted him to say I was a dive instructor.
From there our conversation changed. Right away he said oh, well I guess you know all about PFOs. So, in my case, we had to get it tested to confirm if I had one. He explained the testing process, then said if I do have one, we would get it closed as soon as possible. He went on to explain the closing process to me. To close it, they would do surgery on my leg, placing a small device in my leg vein. From there the device would travel through my blood stream into my heart closing the hole. He made it sound simple and fairly non-invasive for heart surgery. After the surgery I had just had, this didn’t worry me. He also said no diving until we find out and can evaluate it. Although this was very disappointing, I was still recovering from my intestinal surgery, so it didn’t really disrupt my life too much.
A couple months later I finally got my test. The test I had done is called a TEE, or Transesophageal Echocardiogram. For this test, they would sedate me and put a tube with a camera down my throat. With this camera they would be able to see my heart from the other side than they would for a regular echocardiogram. Seeing the heart from the “back” would result in much better images and they’d be able to have a clearer picture of what’s going on.
From my experience the test was easy. I arrived at the hospital and right away was taken to a ward where I was directed to a bed with a robe on it. I got changed and sat on the bed. A nurse came by shortly after that and started taking my vitals and asking the standard hospital questions (allergies, when I last ate, any health conditions). They put an IV in my arm and then left me alone for a bit. A few minutes later one of the doctors came to meet me and went over the process and risks, again usual hospital procedures. He told me I would have a sore throat after the test, and may cough up some pink tissue and that if I did that would be fine.
Next the anesthesiologist came by to see me. Again, I was asked the usual questions about medication, drugs, alcohol and any previous conditions. He told me when I got in the testing room, they’d give me some sedation that would make me feel sleepy and out of it, then give me a spray in the back of my throat to numb it, then give me some more sedation at which point I would probably fall asleep. After our chat, the nurse came back and gave me a chance to go to the bathroom, then she wheeled me into the testing room. They administered the first bit of sedation, and I felt the head rush from it right away. The next thing I remember is waking up back in the ward to the doctor telling me it was
done. Straight away I tried to ask if I had a PFO. My throat was scratchy and hurt but I got the words out. He said no. He went on to say my heart looked really good and said more positive things, but after confirming I did not have a PFO I was bursting with happiness and sedation, so I quickly fell back to sleep.
When I woke again a nurse asked how I was doing and if I wanted to try to sit up. I did with a bit of phlegmy coughing. My throat burned, so she gave me a lozenge. She said coughing and sore throat was normal, so I laid there for a bit sucking on my lozenge. She came back and asked if I wanted to sit up again, and that went well, so she said they wanted me to eat and drink to ensure my esophagus was doing ok. She gave me apple juice and a sandwich. It hurt to swallow, but otherwise everything went down fine. I got up and walked around a bit, and was feeling fine, so I was good to go. I had arranged a ride before the appointment and so my ride arrived and took me home. For the next couple days my throat was sore when I swallowed, but otherwise no effects from the test, just confirmation that my heart was healthy.
Overall, this experience was very informative, and probably good to have. Although I wasn’t allowed to dive for a bit while everything was unknown, I was still healing from surgery, so it really didn’t matter too much. Hopefully now by reading about my experience, anyone out there who is questioning why they got an undeserved DCI hit knows a chat they may need to have with their doctor and knows that the PFO testing process is an easy one.