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Thread: TCD test for PFO

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    RBW Member gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas's Avatar
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    TCD test for PFO

    I was reading on the http://www.rebreatherworld.com/showthread.php?t=35100 thread
    about the "new" TCD (Transcranial Doppler) for diagnosing PFO

    Can any one point to a recent study comparing the PFO detection methods?

    Also anyone done the test in the EU?
    (most of the google results for clinics doing the test for PFO diagnosis came from the US).
    Whats your feedback?

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    Re: TCD test for PFO

    Nothing at all scientific here, but when I had it done, the technician told me it was (apparently) about 95% as effective as the more effective of the TEE/TTE test ( I can never remember which is the better test)

    He said from what he knew, the only reason it was less effective was due to how well the operator performed the test, not inherent in the test itself.

    I believe the TCD can also detect one kind of shunt the other two tests cannot.

    I think the main limitation is you cannot easily use TCD to aid in fixing the PFO (I could be mis-remembering here) but it's far less invasive than some other methods and much cheaper (I paid $300 US about 2-3 years ago)

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    Re: TCD test for PFO

    Quote Originally Posted by gtzavelas  View Original Post
    Also anyone done the test in the EU?
    I think this was the type of test I had done (Pinch nose, blow & hope not to see any bubbles..) by Dr Peter Wilmshurst at the Royal Shrewsbury Hospital, UK. However, although this is in the EU - you can't pay to have the test done there.... you have to be errr referred

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    Re: TCD test for PFO

    Correct, it is a simple test and reliable, however it shows up all/any shunts not just PFO. I know the French Navy use this for screening recruits for diver training, quick, cheap, difficult to get wrong.

    Joe

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    Re: TCD test for PFO

    Sorry guys, but i have done the test with a detector that was placed on my thorax, above my heart, then pressure again your blocked nose (or pressure into your waist like sitting on the toilette) and when they don´t see anything from the contrast medium passed over from right to left heart you don´t have a PFO (99 %), but transcranial...?????

    I have done this at Uniklinik Düsseldorf in Germany

    We should call Doug Ebersole here on RBW....

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    Re: TCD test for PFO

    Here is my 2 cents as a rebreather diver/instructor who is also a cardiologist who closes PFOs for a living.

    Transcranial doppler is not a new test for detection of a PFO. The way it works is to inject microbubbles into a peripheral vein and then "listen" for bubbles in the arterial circulation going to the brain. The concept is that these microbubbles should go back to the right side of the heart and be filtered by the lung, thus never reaching the arterial circulation. If there is a right to left shunt (whether that is a PFO, another intracardiac shunt, or a pulmonary shunt), the bubbles can bypass the filtering effect of the lungs and show up in the arterial circulation. These bubbles are then "heard" by the transcranial doppler. For this reason, it is a very sensitive test for detecting a shunt but cannot localize where the shunt is coming from.

    Either a transthoracic (from the chest wall) or transesophageal echo (from the throat) are very good at defining a shunt coming from the heart as they both image the heart directly. A transesophageal echo (TEE) is definitely the better of the two but is, obviously, more invasive as well, requiring IV sedation. Both use an injection of microbubbles to directly image the bubbles crossing from the right to the left side of the heart. If bubbles appear in the left heart but not immediately (say, after several heart beats) this suggests the shunt is within the lungs.

    As a screening test, transcranial doppler is a good test as it is simple, noninvasive, and if it is normal you can pretty well exclude a shunt. However, if the clinical suspicion of a shunt by history is very high, it is better (in my opinion) to skip the transcranial doppler and move directly to an echo study, usually a transesophageal echo.

    The takehome message is that there is not one perfect test for every person in every clinical presentation. Like everything else in medicine, it requires judgement. You can't just have a "cook book" approach to things.

    Doug

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    Re: TCD test for PFO

    From the patient side, I just had a transesophageal echo this morning after having several mild CNS hits and it was really a piece of cake. In and out in a few hours and I feel no after effects at all. The worse part was the IV insertion (I am a bit of a needle weenee), but that was it. Seems I have a good sized one and now deciding what to do.

    Bruce

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    Re: TCD test for PFO

    Quote Originally Posted by Reefhugger  View Original Post
    From the patient side, I just had a transesophageal echo this morning after having several mild CNS hits and it was really a piece of cake. In and out in a few hours and I feel no after effects at all. The worse part was the IV insertion (I am a bit of a needle weenee), but that was it. Seems I have a good sized one and now deciding what to do.

    Bruce
    First thing to do is contact Doug Ebersole and participate in his study.

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    Re: TCD test for PFO

    Quote Originally Posted by debersole  View Original Post
    Here is my 2 cents as a rebreather diver/instructor who is also a cardiologist who closes PFOs for a living.

    Transcranial doppler is not a new test for detection of a PFO. The way it works is to inject microbubbles into a peripheral vein and then "listen" for bubbles in the arterial circulation going to the brain. The concept is that these microbubbles should go back to the right side of the heart and be filtered by the lung, thus never reaching the arterial circulation. If there is a right to left shunt (whether that is a PFO, another intracardiac shunt, or a pulmonary shunt), the bubbles can bypass the filtering effect of the lungs and show up in the arterial circulation. These bubbles are then "heard" by the transcranial doppler. For this reason, it is a very sensitive test for detecting a shunt but cannot localize where the shunt is coming from.

    Either a transthoracic (from the chest wall) or transesophageal echo (from the throat) are very good at defining a shunt coming from the heart as they both image the heart directly. A transesophageal echo (TEE) is definitely the better of the two but is, obviously, more invasive as well, requiring IV sedation. Both use an injection of microbubbles to directly image the bubbles crossing from the right to the left side of the heart. If bubbles appear in the left heart but not immediately (say, after several heart beats) this suggests the shunt is within the lungs.

    As a screening test, transcranial doppler is a good test as it is simple, noninvasive, and if it is normal you can pretty well exclude a shunt. However, if the clinical suspicion of a shunt by history is very high, it is better (in my opinion) to skip the transcranial doppler and move directly to an echo study, usually a transesophageal echo.

    The takehome message is that there is not one perfect test for every person in every clinical presentation. Like everything else in medicine, it requires judgement. You can't just have a "cook book" approach to things.

    Doug
    Doug,

    I want to thank you for your willingness to provide your considerable expertise on these matters. Having been worked up a couple times for fairly serious disorders I have learned that the physician that is interpreting the tests / reading the films etc. is a key element in the process.

    Your continued willingness to help, as both a diver and physician make RBW a valued resource.

    Tobin

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    Re: TCD test for PFO

    Quote Originally Posted by Reefhugger  View Original Post
    From the patient side, I just had a transesophageal echo this morning after having several mild CNS hits and it was really a piece of cake.
    Bruce
    hi Bruce but i must say you are on something good to say the TEE is a piece of cake. at no time did i find swallowing a probe easy or fun, not to mention the bitter taste of the lidocaine..
    IMHO as a patient the TCD is the easiest way to screen for an issue, then if there is an issue get the TEE to get the "details" per-say of the problem.
    i know doug drugged me well for my TEE as i was still stoned for two days after but it still was no piece of cake
    mel

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