New published paper on PFOs

[tridacna]

Doesn't this depend on the type of PFO? Some are only detectable on autopsy by using a probe. They don't usually have an associated shunt. Even clearing your ears using a Valsalva can push blood right to left across a PFO. So even if it's just probe patent, you could cause a R -> L shunt.

 

[Duke Dive Medicine]

Doesn't this depend on the type of PFO? Some are only detectable on autopsy by using a probe. They don't usually have an associated shunt. Even clearing your ears using a Valsalva can push blood right to left across a PFO. So even if it's just probe patent, you could cause a R -> L shunt.

I think what you're asking is whether the size and morphology (shape/structure) of the PFO influence the amount of shunting; if so, then definitely yes. As you pointed out, some are so small or tight that they don't shunt at all. Others shunt only with increased intrathoracic pressure, and others will shunt at rest. The Valsalva maneuver that divers are taught to perform in order equalize their middle ear spaces (with apologies in advance to @Angelo Farina ) is different than the Valsalva maneuver used to increase intrathoracic pressure when testing for PFO. The latter involves bearing down as if trying to have a bowel movement. Hopefully nobody is trying to clear their ears that vigorously.

PFO testing involves injecting some form of ultrasound contrast material, either sterile 0.9% saline solution that's been agitated to create microbubbles or a manufactured product. The contrast will appear in the right side of the heart soon after it's injected. The sonographer will look for shunting to the left side of the heart at rest, then will ask the patient to bear down and look for shunting with Valsalva as described above. When papers on PFO mention bubble grades, they're talking about the microbubbles in the agitated saline that have shunted during testing. Higher bubble grades mean a more robust shunt.

Best regards,
DDM

 

[tridacna]

I think what you're asking is whether the size and morphology (shape/structure) of the PFO influence the amount of shunting; if so, then definitely yes. As you pointed out, some are so small or tight that they don't shunt at all. Others shunt only with increased intrathoracic pressure, and others will shunt at rest. The Valsalva maneuver that divers are taught to perform in order equalize their middle ear spaces (with apologies in advance to @Angelo Farina ) is different than the Valsalva maneuver used to increase intrathoracic pressure when testing for PFO. The latter involves bearing down as if trying to have a bowel movement. Hopefully nobody is trying to clear their ears that vigorously.

PFO testing involves injecting some form of ultrasound contrast material, either sterile 0.9% saline solution that's been agitated to create microbubbles or a manufactured product. The contrast will appear in the right side of the heart soon after it's injected. The sonographer will look for shunting to the left side of the heart at rest, then will ask the patient to bear down and look for shunting with Valsalva as described above. When papers on PFO mention bubble grades, they're talking about the microbubbles in the agitated saline that have shunted during testing. Higher bubble grades mean a more robust shunt.

Best regards,
DDM

Thanks for the edification. My point is this 25% boogeyman that is constantly mentioned (# of PFO in gen pop). I wonder what the size criteria is that could effect a DCS incident in a susceptible diver? How robust does the shunt have to be?

 

[Duke Dive Medicine]

Thanks for the edification. My point is this 25% boogeyman that is constantly mentioned (# of PFO in gen pop). I wonder what the size criteria is that could effect a DCS incident in a susceptible diver? How robust does the shunt have to be?

There are a lot of individual variables. 25-30% of the population has a PFO, but only 8-10% have a detectable shunt. Someone with a PFO that only shunts on valsalva could suffer sudden-onset DCS while straining to move tanks around after a provocative dive, while another diver with a relatively large PFO that shunts at rest could dive for 30 years and never suffer from DCS depending on how conservatively they dive and their individual tendency to bubble after diving.

Best regards,
DDM

 

[wetb4igetinthewater]

The latter involves bearing down as if trying to have a bowel movement. Hopefully nobody is trying to clear their ears that vigorously.

Hahahahahahaha!!! Now I have an image in my head of divers clenching down, their eyes closed, faces grimacing, hands balled up into a fist. Thanks for the laugh to start my day!

 

[Esprise Me]

Apparently the Warhammer can kill you before your buddies get the chance!

 

[tridacna]

Apparently the Warhammer can kill you before your buddies get the chance!

I saw the original Warhammer pics. There was no strain involved. Au contraire - through the eye of a needle at 50 paces!

 

[sea_ledford]

Hahahahahahaha!!! Now I have an image in my head of divers clenching down, their eyes closed, faces grimacing, hands balled up into a fist. Thanks for the laugh to start my day!

I've seen divers do that. Freaks me out every time. I'm sure my "Stop effing doing that!" signal is pretty funny too!

 

[Marie13]

Hahahahahahaha!!! Now I have an image in my head of divers clenching down, their eyes closed, faces grimacing, hands balled up into a fist. Thanks for the laugh to start my day!

That goes so well with a certain recent thread.

 

[rddvet]

I had my pfo closed 3 weeks ago as of yesterday. Procedure wasn’t nearly as bad as it could’ve been. I could have gone to work the next day, but took off. I have had one very big issue. As of Sunday (2.5 weeks post surgery) I am having a pretty severe allergic reaction to Plavix. The reaction is not fun. I had to go to urgent care Sunday because my lips, eyes, and entire trunk were covered in hives. I’m better every day, though it will likely be another week for all symptoms to resolve. I would still at this point do the procedure again.
Plavix reactions are apparently very very common. Initially I was concerned it was a reaction to the device