Radiation and coronary disease

Discussion in 'Health and medical' started by Patrick Blancha, Dec 17, 2003.

  1. http://tinyurl.com/z9w4

    Radiation appears to induce coronary artery disease. Why then have radioactive stents and external
    beam radiation (brachytherapy) become popular?

    Patrick Blanchard MD

    --
    SonoScore Winnning against heart attack and stroke http://www.sonoscore.com
     
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  2. Patrick Blanchard MD wrote:

    > http://tinyurl.com/z9w4
    >
    > Radiation appears to induce coronary artery disease. Why then have radioactive stents and external
    > beam radiation (brachytherapy) become popular?

    Brachytherapy has been shown to inhibit recurrent in-stent restenosis, Patrick.

    Humbly,

    Andrew

    --
    Dr. Andrew B. Chung, MD/PhD
    Board-Certified Cardiologist
    http://www.heartmdphd.com/
     
  3. On Mon, 15 Dec 2003 13:38:06 -0500, Dr. Andrew B. Chung, MD/PhD
    <[email protected]> wrote:

    > Patrick Blanchard MD wrote:
    >
    >> http://tinyurl.com/z9w4
    >>
    >> Radiation appears to induce coronary artery disease. Why then have radioactive stents and
    >> external beam radiation (brachytherapy) become popular?
    >
    > Brachytherapy has been shown to inhibit recurrent in-stent restenosis, Patrick.
    >
    > Humbly,
    >
    > Andrew
    >
    > --
    > Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/
    >
    >
    >
    Yes, but I understand the long term patency studies show otherwise. Long term patency rates are not
    as promising as the short term (less than 1 year). Why is this? What is it about radiation that is
    beneficial and what about it is harmful?

    --
    ~~~ Patrick Blanchard, M.D., A.B.F.P. Board Certified in Family Practice
    http://www.familydoctor.org/blanchard ~~~ SonoScore Winning against heart attack and stroke
    http://www.sonoscore.com
     
  4. "Patrick Blanchard, M.D." wrote:

    > On Mon, 15 Dec 2003 13:38:06 -0500, Dr. Andrew B. Chung, MD/PhD
    > <[email protected]> wrote:
    >
    > > Patrick Blanchard MD wrote:
    > >
    > >> http://tinyurl.com/z9w4
    > >>
    > >> Radiation appears to induce coronary artery disease. Why then have radioactive stents and
    > >> external beam radiation (brachytherapy) become popular?
    > >
    > > Brachytherapy has been shown to inhibit recurrent in-stent restenosis, Patrick.
    > >
    > > Humbly,
    > >
    > > Andrew
    > >
    > > --
    > > Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/
    > >
    > >
    > >
    > Yes, but I understand the long term patency studies show otherwise. Long term patency rates are
    > not as promising as the short term (less than 1 year). Why is this?

    Long term speaks to a process (progression of atherosclerosis) that is different from restenosis
    (neointimal hyperplasia).

    > What is it about radiation that is beneficial

    Halts neointimal hyperplasia (the over-proliferation of smooth muscle cells in response to injury).

    > and what about it is harmful?

    Damages endothelial cells increasing local rates of atherosclerosis.

    Humbly,

    Andrew

    --
    Dr. Andrew B. Chung, MD/PhD
    Board-Certified Cardiologist
    http://www.heartmdphd.com/
     
  5. Dr Chaos

    Dr Chaos Guest

    Dr. Andrew B. Chung, MD/PhD <[email protected]> wrote:
    > Halts neointimal hyperplasia (the over-proliferation of smooth muscle cells in response to
    > injury).
    >
    >> and what about it is harmful?
    >
    > Damages endothelial cells increasing local rates of atherosclerosis.

    Would you suppose that paclitaxel or sirolimus coated stents would be a superior therapy, short and
    long term, to anti-restenosis radiation then?
     
  6. On Mon, 15 Dec 2003 14:00:32 -0500, Dr. Andrew B. Chung, MD/PhD
    <[email protected]> wrote:

    > "Patrick Blanchard, M.D." wrote:
    >
    >> On Mon, 15 Dec 2003 13:38:06 -0500, Dr. Andrew B. Chung, MD/PhD
    >> <[email protected]> wrote:
    >>
    >> > Patrick Blanchard MD wrote:
    >> >
    >> >> http://tinyurl.com/z9w4
    >> >>
    >> >> Radiation appears to induce coronary artery disease. Why then have radioactive stents and
    >> >> external beam radiation (brachytherapy)
    >> become
    >> >> popular?
    >> >
    >> > Brachytherapy has been shown to inhibit recurrent in-stent restenosis, Patrick.
    >> >
    >> > Humbly,
    >> >
    >> > Andrew
    >> >
    >> > --
    >> > Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/
    >> >
    >> >
    >> >
    >> Yes, but I understand the long term patency studies show otherwise. Long term patency rates are
    >> not as promising as the short term (less than 1 year). Why is this?
    >
    > Long term speaks to a process (progression of atherosclerosis) that is different from restenosis
    > (neointimal hyperplasia).

    You did not address my question: Why is it that long term patency rates for radioactive stents or
    external beam radiation are poor?

    Certainly the data indicate radiation causes upregulation of atherosclerosis by stimulating
    neointimal hyperplasia. In fact, injury (of any kind) to the intima will cause a neointimal
    hyperplasia. Neointimal hyperplasia is considered to the be initial step of atherosclerosis induced
    by injury, is it not?

    >
    >> What is it about radiation that is beneficial
    >
    > Halts neointimal hyperplasia (the over-proliferation of smooth muscle cells in response to
    > injury).

    The radiation injures the intima, but yet it appears to initially halt the injury response. If you
    irradiate any tissue enough, it would probably halt any growth. Howver, it appears that the intima
    eventually recovers, leading to an injury response, resulting in upregulation of atherosclerosis in
    the coronary artery and eventual acceleration of the very process the radiation is supposed to be
    retarding. Don't you find this approach flawed? If you reason out the mechanism, it appears to go
    against "primum non nocere" first do no harm. I think this is an example of "hurry up and do
    something, anything".

    >
    >> and what about it is harmful?
    >
    > Damages endothelial cells increasing local rates of atherosclerosis.

    The irony is that this therapy accelerates the very process it is trying to abolish.

    >
    > Humbly,
    >
    > Andrew
    >
    > --
    > Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/
    >

    --
    ~~~ Patrick Blanchard, M.D., A.B.F.P. Board Certified in Family Practice
    http://www.familydoctor.org/blanchard ~~~ SonoScore Winning against heart attack and stroke
    http://www.sonoscore.com
     
  7. Anonymous

    Anonymous Guest

    "Dr Chaos" <[email protected]> wrote in message
    news:[email protected]...
    > Dr. Andrew B. Chung, MD/PhD <[email protected]> wrote:
    > > Halts neointimal hyperplasia (the over-proliferation of smooth muscle
    cells in
    > > response to injury).
    > >
    > >> and what about it is harmful?
    > >
    > > Damages endothelial cells increasing local rates of atherosclerosis.
    >
    > Would you suppose that paclitaxel or sirolimus coated stents would be a superior therapy, short
    > and long term, to anti-restenosis radiation then?

    Sorry to jump in here. That's what I've been told the research studies show - except at the edges of
    the stents where less of the drugs are delivered. Also the drug eluting stents are fairly new and
    most restenosis happens in the relatively near term, so I don't know how long the follow up was.

    Incidentally, I have a theory that you could use radiation at the edges, but the combination would
    be very expensive.

    Bill

    Bill
     
  8. Dr Chaos wrote:

    > Dr. Andrew B. Chung, MD/PhD <[email protected]> wrote:
    > > Halts neointimal hyperplasia (the over-proliferation of smooth muscle cells in response to
    > > injury).
    > >
    > >> and what about it is harmful?
    > >
    > > Damages endothelial cells increasing local rates of atherosclerosis.
    >
    > Would you suppose that paclitaxel or sirolimus coated stents would be a superior therapy, short
    > and long term, to anti-restenosis radiation then?

    That is the hope.

    Humbly,

    Andrew

    --
    Dr. Andrew B. Chung, MD/PhD
    Board-Certified Cardiologist
    http://www.heartmdphd.com/
     
  9. "Patrick Blanchard, M.D." wrote:

    > On Mon, 15 Dec 2003 14:00:32 -0500, Dr. Andrew B. Chung, MD/PhD <[email protected]> wrote:
    >
    > > "Patrick Blanchard, M.D." wrote:
    > >
    > >> On Mon, 15 Dec 2003 13:38:06 -0500, Dr. Andrew B. Chung, MD/PhD <[email protected]>
    > >> wrote:
    > >>
    > >> > Patrick Blanchard MD wrote:
    > >> >
    > >> >> http://tinyurl.com/z9w4
    > >> >>
    > >> >> Radiation appears to induce coronary artery disease. Why then have radioactive stents and
    > >> >> external beam radiation (brachytherapy)
    > >> become
    > >> >> popular?
    > >> >
    > >> > Brachytherapy has been shown to inhibit recurrent in-stent restenosis, Patrick.
    > >> >
    > >> > Humbly,
    > >> >
    > >> > Andrew
    > >> >
    > >> > --
    > >> > Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/
    > >> >
    > >> >
    > >> >
    > >> Yes, but I understand the long term patency studies show otherwise. Long term patency rates are
    > >> not as promising as the short term (less than 1 year). Why is this?
    > >
    > > Long term speaks to a process (progression of atherosclerosis) that is different from restenosis
    > > (neointimal hyperplasia).
    >
    > You did not address my question: Why is it that long term patency rates for radioactive stents or
    > external beam radiation are poor?
    >

    Actually, I did. To put it another way, high dose radiation, while inhibiting the neointimal
    hyperplasia that leads to in-stent restenosis does not appear to inhibit progressive
    atherosclerosis.

    >
    > Certainly the data indicate radiation causes upregulation of atherosclerosis by stimulating
    > neointimal hyperplasia.

    Not at the high doses for brachytherapy. Far field mantle radiation is associated with increased
    rates of atherosclerosis but the degree of exposure seen by the coronaries are much less than that
    for brachytherapy.

    > In fact, injury (of any kind) to the intima will cause a neointimal hyperplasia.

    Yes with the exception of high doses of radiation which impair neointimal hyperplasia.

    > Neointimal hyperplasia is considered to the be initial step of atherosclerosis induced by injury,
    > is it not?
    >

    Not really. By itself, injury, does not cause atherosclerosis.

    >
    > >
    > >> What is it about radiation that is beneficial
    > >
    > > Halts neointimal hyperplasia (the over-proliferation of smooth muscle cells in response to
    > > injury).
    >
    > The radiation injures the intima, but yet it appears to initially halt the injury response.

    Because at high enough doses, it also injures smooth muscle cells (and precursor cells) located in
    the media and adventitia, impairing their ability to either replicate or migrate into the damaged
    (and stented) area.

    > If you irradiate any tissue enough, it would probably halt any growth.

    Correct.

    > Howver, it appears that the intima eventually recovers,

    Yes.

    > leading to an injury response,

    A recovered intima inhibits the injury response.

    > resulting in upregulation of atherosclerosis in the coronary artery

    Only in those areas where the dose was not sufficient to inhibit the injury response.

    > and eventual acceleration of the very process the radiation is supposed to be retarding.

    Ditto.

    > Don't you find this approach flawed?

    It works.

    > If you reason out the mechanism, it appears to go against "primum non nocere" first do no harm.

    It prevents in-stent restenosis which would cause harm.

    > I think this is an example of "hurry up and do something, anything".

    That is one way of looking at prevention.

    >
    >
    > >
    > >> and what about it is harmful?
    > >
    > > Damages endothelial cells increasing local rates of atherosclerosis.
    >
    > The irony is that this therapy accelerates the very process it is trying to abolish.
    >

    Only in areas where the radiation dose was inadequate.

    Humbly,

    Andrew
    --
    Dr. Andrew B. Chung, MD/PhD
    Board-Certified Cardiologist
    http://www.heartmdphd.com/
     
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