More on PFO, “That Perfectly Formed Hole”

After our November item on patent foramen ovale (PFO), the heart issue in which there is a tiny hole between chambers, Mike Hofman (San Francisco, CA) wrote about having his (PFO) plugged:

"I was diagnosed January 2015 (after 20 years or so of skin bends, hip pain, and related symptoms which previously had been ascribed by a neurologist as lower disk compression) and had it closed in July 2015. The interventionist cardiologist had researched PFOs and inserted the 'plug' with no problem. After six months, I was cleared for diving (until then, I could go only to 30 feet). A side benefit (maybe just imaginary) was slightly more energy and fewer headaches.

"For six months, I could make no dives deeper than 30 feet. I now have no restrictions to my diving and a letter from my cardiologist to that effect."

A recent abstract in the journal of the Undersea & Hyperbaric Medical Society states that PFO problems in divers is much less than one might predict:

"A PFO is highly associated with complex injuries in divers, including severe neurological decompression sickness, inner ear decompression, and cutis marmorata. While 20-30 percent of divers are expected to have a PFO based on PFO incidence in the general population, DCS in recreational divers with PFO occurs in only 0.05-0.08 percent of dives. This is a much lower incidence than the one-to-five PFO cases expected if every diver with a PFO developed DCS. Recreational divers are generally not screened for PFOs unless a severe case of DCS develops or DCS occurs despite adherence to recreational dive limits." (UHM 2021, Vol48 No3)

Undercurrent also had an email from Dr. Peter Germonpré of the European Underwater & Baromedical Society, and author of PFO and the Diver, who took issue with our explanation of a PFO and its closure.

He says, "A PFO has no influence, that we know of, on the speed of off-gassing, and only allows inert gas bubbles to re-enter the circulation towards the tissues.

"The bubbles enter directly into the arterial circulation (in the oxygenated blood) and may embolize into the brain and other tissues, where they can remain trapped and grow because of the residual nitrogen (inert gas) still present in the tissue.

"Cardiologists tend to be overly invasive, and the closure procedure has in itself risks that are much higher than diving 'correctly' with a PFO. So, the first option should be modifying the dive profiles and behavior to reduce the possibility of venous inert gas bubbles. Closing the PFO should never be the first option. It is costly, has a higher risk than diving conservatively, and as illustrated [in the original article in Undercurrent], diving extremely may still get you bent."