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  1. #1
    unregistered Guest

    Default Using Bovine Carotid Artery for Stenosis Revision

    Hi Dr. Agar,

    I was reading your post about it is better using your native veins for fistula repair etc... but my question is....What if there is someone out there who has been tested and found to have no viable vein segment in the body ( leg and elsewhere) to use to bypass a stenosis?

    What is your general opinion on using a bovine carotid artery instead of a graft segment to use to bypass the stenosed area for a revision? Is this better than using graft material since it is closer to the human vein than the man made graft? It seems as there is little information on this available.

    Also, just to put this out there, since they are able to use animal tissue such as the bovine artery, why is it that they cannot use a doner vein from a sibling? If they can use decellulazrized animal tissue, why is it they do not do the same with a donor from say a brother/sister? I would think this would be much better than an animal segment?

    Any thoughts?

    thanks

  2. #2
    Join Date
    11-17-09
    Location
    Geelong, Victoria, Australia
    Posts
    413

    Default

    Interesting question ... will get to answer tomorrow afternoon

  3. #3
    Join Date
    11-17-09
    Location
    Geelong, Victoria, Australia
    Posts
    413

    Default Great question - fun answer! Thanks!

    This is a fascinating post – and thank-you for the question. It has revived old memories and stimulated forward thought - all in one post.

    I suppose I should preface by saying that research into and advances in arterio-venous fistula alternatives isn’t my area – far from it – as I guess I would class myself as a fistula user, rather than a fistula creator.

    But, back in the 70’s, and 80’s, the use of bovine (cow-derived) graft vessels for AVF use was a really ‘hot-to-trot’ topic.

    Indeed – and this is fair dinkum (OZ for ‘utterly true’) – I have exactly that - a bovine graft, about 1 foot long, nicely curved, fuzzy at its edges - sitting in 1L of saline in a sterile plastic pack, on my bookshelf, in my office, behind my office desk … if this site took photos, I’d addend it … salvaged from a research project here in the 80’s! True! I have! I was given it as a present - odd presents I get, eh? - back in the mid 80's when I was a young and, then, inquiring nephrologist.

    I have often wondered if it could still be used … don’t worry, any Geelong patients who may read this, I won’t trial it on you! But, seriously, it was a technology ‘going places’… back then!

    What’s happened since?

    Well, primarily, we have developed (potentially) better stem cell biology such that with the combination of stem cell advances and angiology (the science of growing new blood vessels … or, ‘angiogenesis’) the growth of human stem cell-derived vascular beds, probably shows greater promise.

    There is stuff happening here!

    Good stuff.

    Stuff that has at least the potential to take a patient’s cells – endothelial cells (the cells that line the internal walls of blood vessels) and attach and grow them - living cells - on an inert substrate (a backing structure) to form an artificial blood vessel … not one of a cow (bovine) but of a (1) human and (2) more importantly, the very human requiring the new blood vessel : you!

    Just as we can bone marrow, or renal, or pancreas, or heart, or lung transplant … medical science is close to specific ‘cell’ transplanting to grow ‘bits’ to measure, including vessels.

    OK … step back a moment. Close?

    Close is always a matter of degree. What is ‘close’ to a researcher needs to be ‘now’ for the recipient of the research … and ‘close’ is never ‘now’.

    So don’t go off thinking this is next year … far from it. But, coming? – in your time or the next? – yes.

    As for using brother/sister donor vessels? That’s not so easy as it seems.

    Blood vessels actually bear the brunt of any immunological attack and the laws of transplantation and rejection would still hold … yes … even for something seemingly as small and ‘insignificant’ as a section of vein. So using donor vessels for arterio-venous fistulae just ‘ain’t the answer’ … sorry … but, as they say, them’s the breaks!

    The greatest home lies in angiogenesis and autologous (from the same person) vessel engineering through stem cell or other tissue growth methods where the patient’s own cells are used to make the vessel that forms the fistula.

    Back to your bovine proposition … cow vessels seemed to die a slow, silent death. Why? Well, they never worked well, stem cell research and research into the ‘promoters’ of angiogenesis took off … and suddenly awesome, fuzzy cow vessels, like the one on the shelf in my office , looked unappealing. As I take it down and gaze at it as I type to you, I am also and again made to ponder … ‘why’.

  4. #4
    Join Date
    05-13-07
    Location
    Lynchburg, VA
    Posts
    121

    Default

    Dr. Agar,

    Thanks for the response. i just wanted to add, I have been to 3 different vascular surgeons in 3 different states for a second and third opinion. It is amazing how the 3 surgeons not only had totally different comfort levels but also 3 totally different views on salvaging a fistula. Two wanted to just start from scratch rather than try to corrent/revise it. This is a bit scary in my opinion.

    I know that you cannot give me specific recommendations, But wanted to know your general thoughts on the bovine artery to bypass a stenosed area. ( the segment would not have to be stuck with any needles)

    Dr. Agar, I want to thank you for your input. Also, I wanted to thank you for the great presentation at the NxStageUsers Conference 2 Weeks ago. If this topic comes your way again and there is anything you could share, I would apprecieate it.

    Regards,

    Miracleman
    Brian Riddle
    _________________________________
    3 Transplants - 2 living related
    CAPD Peritoneal - 13 years
    NxStage Since 4/2006
    Facebook: Dialysis Discussion Uncensored
    Member of www.HomeDialysis.org
    _________________________________

  5. #5
    Join Date
    11-17-09
    Location
    Geelong, Victoria, Australia
    Posts
    413

    Default More information about BCAG

    Dear Brian

    I have looked further. The available evidence - to my thinking - still doesn't support good outcomes bovine carotid artery (BCA) grafts ... so I stand by my previous statements that native is best and always best and should be used as the first to last resort!

    I accept that, rarely, native vein harvest may not be possible. If so, the primary failure rates and infective risks for BCA grafts still seem to exceed those for PTFE grafts in the majority of studies I can find - and these remain old studies.

    That said, I have found a reference to a recent study (completed) at the Massachussets General Hospital (MGH)into a further comparison of BCA grafts vs PTFE grafts ... but cannot find the results - the study documents say 'results not yet available'. So, clearly, some are still following the BCA line of inquiry. http://www.clinicaltrial.gov/ct2/sho...ts/NCT01021839

    This is not to say that someone somewhere isnt (a) exploring (b) have success with BCA grafts. They may be. But, let's just say that it is a procedure that is not thick on the ground right now, we don't use them here and I am personally not aware of resounding outcome stories from elsewhere.

    There has also been some work on bovine mesenteric veins . These are veins that are harvested [or taken] from the supportive web-like membrane [the mesentery] that supports the blood vessels that supply the gut with blood [mesenteric arteries] and the veins [mesenteric veins] which then drain the blood with its absorbed nutrients back to the liver for metabolic use. My understanding is ... though remember my first post comment that this is getting well out of my area of expertise ... that this work has been no more sustainedly successful, overall, than the BCA graft research.

    I also still think the longer-term future augers best (in the 'artificial' vessel field) in angiogenesis via angiogenic growth factors combined with either endothelial harvest or stem cell to endothelial transformative culture applied to a architectural vessel wall substrate to 'grow' native autologous vessels for re-use. While this is still the stuff of future years - NB: it's not now - this work is well advanced in a number of labs both here in Australia and in the US. One easy-to-read report from the Massachussets Institute of Technology (MIT: 2007) describes some of the progress of this work and can be found at http://www.technologyreview.com/biomedicine/19693/

    Till then, the best data I can find (excluding the so-far unreleased data from the MGH study in the US) is the best part of a decade old. Typing ... as I have ... 'bovine carotid artery hemodialysis' into my Google browser (where was I before Google?) yields a raft of surgical abstracts - though almost all are from the 1970s - with only the standout on recent work being the MGH research paper (as I have linked above).

    That is probably all I can provide on the topic that is of help. I hope it answers at least some of your questions.
    Last edited by John Agar; October 27, 2010 at 03:07 AM.

  6. #6
    Unregistered Guest

    Default Mass General Study Results

    Dear Dr. Agar,
    As CEO of the USA-based manufacturer of the BCA, ARTEGRAFT, I would like to send you the 3-year clinical results. The outcomes are compelling. Our graft is only sold in the USA and has been in continuous clinical use for 40 years. Please e-mail me at info@artegraft.com.
    Sincerely,
    Rick Gibson

  7. #7
    Join Date
    11-17-09
    Location
    Geelong, Victoria, Australia
    Posts
    413

    Default

    Thank you for this information.

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