Air Embolism and Patent Foramen Ovale

[rwmaloney]

Dive Medicine from , M.D.
I have had a patient who logged more that 800 dives many with tri mix. She had recent minor symptoms and minor clinical occurences with suspicions for Arterial air embolization even with an END of 70 and very conservative diving dynamics. So I went looking for the level of risk she may have. First a MRI was performed revealing left frontal lobe infarct (brain) - old and assymtomatic. Cardiac ECHO revealed as expected a patent foramen ovale (pfo) with a right to left atrial shunt of blood. That means bubbles forming in the venous system are regularly moving into the arterial circulation. Remember dive tables are determined be doppler determining small bubbles forming in the venous circulation. 10-20% of the population have PFO so if you have had any concerns check it out. If you are having a cardiac echo done ask (demand) for a (bubble test) also. I have been on two dive trips where healthy divers have died this may have been the cause. With this problem you have 3 times the risk of death with each dive and 100 times with deco. Duke Univ treated 91 divers with sever life threatening Deco sickness 39 had PFO. Of those 60% 70% of the 39 had PFO.
Do not do technical deep diving without this knowledge or a huge life ins. policy
If you wish further info contact me.

 

[DocVikingo]

Hi rwmaloney,

Actually, your estimate of "10-20% of the population have PFO so if you have had any concerns check it out" is on the low side.

It's probably closer to 25% in the general population:

1. "Mayo Clin Proc. 1984 Jan;59(1):17-20.

Incidence and size of patent foramen ovale during the first 10 decades of life: an autopsy study of 965 normal hearts.Hagen PT, Scholz DG, Edwards WD.
The incidence and size of the patent foramen ovale were studied in 965 autopsy specimens of human hearts, which were from subjects who were evenly distributed by sex and age. Neither incidence nor size of the defect was significantly different between male and female subjects. The overall incidence was 27.3%, but it progressively declined with increasing age from 34.3% during the first three decades of life to 25.4% during the 4th through 8th decades and to 20.2% during the 9th and 10th decades. Among the 263 specimens that exhibited patency in our study, the foramen ovale ranged from 1 to 19 mm in maximal potential diameter (mean, 4.9 mm). In 98% of these cases, the foramen ovale was 1 to 10 mm in diameter. The size tended to increase with increasing age, from a mean of 3.4 mm in the first decade to 5.8 mm in the 10th decade of life."

2. Mayo Clin Proc. 1999 Sep;74(9):862-9.
Prevalence of potential risk factors for stroke assessed by transesophageal echocardiography and carotid ultrasonography: the SPARC study. Stroke Prevention: Assessment of Risk in a Community.

Meissner I, Whisnant JP, Khandheria BK, Spittell PC, O'Fallon WM, Pascoe RD, Enriquez-Sarano M, Seward JB, Covalt JL, Sicks JD, Wiebers DO.

Department of Neurology, Mayo Clinic Rochester, Minn 55905, USA.

OBJECTIVE: The SPARC (Stroke Prevention: Assessment of Risk in a Community) study was designed to identify risk factors for stroke and cardiovascular disease using transesophageal echocardiography and carotid ultrasonography. This protocol was undertaken to establish a cohort in which putative risk factors for stroke were identified so that subsequent follow-up could discern the roles these risk factors play in stroke incidence. SUBJECTS AND METHODS: This was a prospective, population-based study. A randomly selected cohort comprised 1475 Olmsted County, Minnesota, residents aged 45 years or older, of whom 588 agreed to participate. Transesophageal echocardiography and carotid ultrasonography were used for evaluation of the subjects. Prevalences of various cardiovascular and cerebrovascular conditions were determined. RESULTS: Transesophageal echocardiography was successfully completed in 581 subjects. The prevalence (+/-SE) of patent foramen ovale was 25.6% (+/-1.9%), and that of atrial septal aneurysm was 2.2% (+/-0.6%). The prevalence of aortic atherosclerosis increased with age and was most common in the descending aorta, particularly in subjects 75 to 84 years old. The prevalence of strands on native valve was 46.4% (+/-2.2%). Carotid ultrasonography data for 567 participants revealed minimal atherosclerotic disease. Most subjects had minimal or mild carotid occlusive disease. The prevalence of moderate (50%-79%) and severe (80%-99%) stenosis was 7.7% (+/-1.1%) and 0.3% (+/-0.2 %), respectively. CONCLUSIONS: This prospective study defines the prevalence of multiple potential cardiovascular and cerebrovascular risk factors, providing population-based data for ongoing follow-up of the risk of stroke."

3. PFO -- Cleveland Clinic
PFO, Patent Foramen Ovale in Adults - congenital heart disease

Regards,

DocVikingo

 

[Doc Intrepid]

Dive Medicine from , M.D.
I have logged more that 800 dives many with tri mix. I had recent minor symptoms and minor clinical occurences with suspicions for Arterial air embolization even with an END of 70 and very conservative diving dynamics. So I went looking for the level of risk I may have. First a MRI revealing left frontal lobe infarct (brain) - old and assymtomatic. Cardiac ECHO reveaved as expected a patent foramen ovale (pfo) with a right to left atrial shunt of blood. That means bubbles forming in the venous system are regularly moving into the arterial circulation. Remember dive tables are determined be doppler determining small bubbles forming in the venous circulation. 10-20% of the population have PFO so if you have had any concerns check it out. If you are having a cardiac echo done ask (demand) for a (bubble test) also. I have been on two dive trips where healthy divers have died this may have been the cause. With this problem you have 3 times the risk of death with each dive and 100 times with deco. Duke Univ treated 91 divers with sever life threatening Deco sickness 39 had PFO. Of those 60% 70% of the 39 had PFO.
Do not do technical deep diving without this knowledge or a huge life ins. policy
If you wish further info contact me.

Congrats on discovering PFO before rather than after a hit. Good luck with that.

I asked for a PFO test. Was told that if I had the test done and it came back positive, then the insurance would pay for the test. If I had the test done and it came back negative, then I would pay for the test. As the costs for the test totaled more than $5k, I elected to live dangerously for awhile longer. If your insurance will pay for the test, no reason not to have it done.

My .02...

 

[DocVikingo]

Hi Doc Intrepid,

You state: "If your insurance will pay for the test, no reason not to have it done."

I believe your statement merits some clarification as there in fact are issues to be considered before having it performed.

"Cardiac ECHO" as used by rwmaloney is a rather non-specific term. Basically, echocardiography of the heart comes in two forms, the transthoracic echocardiogram (TTE) and transesophageal echocardiogram (TEE). At present, TEE with bubble contrast arguably is the gold standard for detecting PFO. This latter procedure involves having the patient lie on the left side. An IV sedative is injected and the throat sprayed with a topical anesthetic. The patient then swallows a tube with an echo transducer affixed to the end. The transducer is positioned in the esophagus, directly behind the heart and rotated to provide images of heart from several different angles. Obviously this procedure is more than trivial.

While relatively safe on balance, TEE can result in breathing problems, abnormal or slow heart rhythm, reaction to the sedative and minor bleeding. In extremely rare cases, TEE may cause perforation or tear of the esophagus.

One needs to be informed about the nature of medical procedures when considering undergoing them.

As an aside, in a healthy diver who is showing no evidence of PFO or other cardiac abnormality the chances are very high that he will in fact end up paying for the entire echocardiography procedure out of his own pocket.

Regards,

DocVikingo

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.

 

[cmalinowski]

Congrats on discovering PFO before rather than after a hit. Good luck with that.

I asked for a PFO test. Was told that if I had the test done and it came back positive, then the insurance would pay for the test. If I had the test done and it came back negative, then I would pay for the test. As the costs for the test totaled more than $5k, I elected to live dangerously for awhile longer. If your insurance will pay for the test, no reason not to have it done.

My .02...

Another reason to detest insurance companies I guess I was lucky in that my doctor wrote a script for it and my insurance paid it (TTE).

Chris

 

[Saturation]

This PFO issue just never seems to end.

Primary Care Diving Medicine: PFO Risk versus DCS Diving Risk

 

[NEDU]

PFO has become quite a contentious issue in recent years. In fact, there are a few countries that exclude anyone from becoming a military diver if they have a PFO. We at NEDU have a current study to try to establish some definitive data on any link between PFO and DCS. There are some extraordinary exaggerations, myths and mischaracterizations out there amongst some real data. We hope to have the study finished up fairly soon and get our info out.

 

[Saturation]

I am extremely happy to see NEDU here, and belated welcome!

 

[DocVikingo]

This PFO issue just never seems to end.[/url]

It's not like we haven't hurled information at it:

Results of a search under PFO:

ScubaBoard - Search Results

Regards,

DocVikingo

 

[D_B]

Question ... My friend says that it's not that doing deco dives puts you significantly more at risk of having DCS if you have a PFO (properly done deco does not) but that it's the increased frequency of your diving that puts the risk higher, if you dive often, then you should be tested for one
... sorry if the answer is already in the info posted