EVOLUTION OF VASCULAR SUBSTITUTES

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EVOLUTION OF VASCULAR SUBSTITUTES

• Prof. Dr. Bonno van Bellen
• Chief of the Department for Vascular Surgery and
  Angiology the Beneficencia Portuguesa Hospital of
  São Paulo

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But the story started some 2700 years BC

• When Si Ling Chi,
• the first empress of China
• was having a cup of tea
• while seated under a tree

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• Seated on her chair, a cocoon felt
• in her cup
• She unraveled the tiny
• threads that formed
• the cocoon, made by
• a small white caterpillar
• She discovered silk
• Discovery was keps secret untill the year 300DC

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• Silk was Chinas most important product for trade
  with the western world
• Mongolian Peace turned the Silk Road between
  China and Europe safer and it was introduced into
  the european culture

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Connection between silk and the development of
substitutes for the human arteries starts to
make sense at the very beginning of the 20st
century
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Alexis Carrel1873 - 1944

• Born in France he got in struggle with the french
  government because of his divergent political
  ideas.
• He leaved France and went to Canada
• Soon he got a laboratory at the University of
  Chicago in the USA where he continued his essays
  in experimental organ transplantation in dogs

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Alexis Carrel1873 - 1944

• In 1912 he received the Nobel Prize in Medicine
  and Physiology for his work in experimental organ
  transplantation and suture techniques for great
  and small blood vessels

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• His techniques could not be used in humans
  because the arterial diseases could not yet be
  visualized and blood used to clot when the
  arteries were submitted to some kind of operation
  

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• Some technique to see the blood vessels had to
  be discovered
• Some way to impede clotting of blood had to be
  discovered

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Wilhelm C. Roentgen1845 - 1923

• Discovered xRays in 1895 and in few years the
  majority of the hospitals where equipped with
  xRay machines
• Roentgen received the Nobel Prize of Physics in
  1901

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Egas Muniz1874 - 1955

• But only in 1943 Egas Muniz made the first
  arteriogram, opening the possibility to visualize
  the diseases of the arteries
• Received the Nobel Prize for Medicine in 1949

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Jay McLean and William Howell
1860 - 1945

• Discovered heparin in 1916, an
• anticoagulant needed to make operations upon
  blood vessels possible without clotting of blood.
• Heparin became available for human use in 1935.

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• We had the fundamentals of the vascular surgical
  techniques - Carrel
• We had the ways to see the arterial disease -
  Roentgen gt Moniz
• We had heparin making direct access to the blood
  vessels possible without clotting gt McLean and
  Howell

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• The first attempts to create a substitute for the
  great arterial vessels of the body started with
  attempts to use conserved human vessels in the
  1940s by Robert Gross in Boston

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• Attempts to substitute a diseased aorta by
  biological and non biological tubes failed
• A conserved human aorta used to dilate and
  rupture
• Non biological tubes made of steel, glass and
  other material clotted down very soon

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In 1951 Charles Dubost in France, replaced an
aortic aneurysm. This was a worthy example of
bold clinical advances with little or no
experimental preparation
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Silk, 4600 years later

• The observation that a silk suture in one of the
  chambers of the heart of a dog became covered
  with a tiny layer of cells became the crucial
  thought that fine threads woven or knitted as a
  tube could replace a sick aorta in an animal and
  maybe in the human being.
• Voorhees AB, Jaretski A and Blakemore AH The
  use of tubes constructed from vinyon-N cloth in
  bridging arterial defects. Ann Surg 135332, 1952

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Voorhees, Jarelski and Blakemore

• Created a synthetic aorta of Vinyon N and used it
  experimentally as a substitute in a dog
• Attempts were followed using other non-biological
  material Orlon, Ivalon, Teflon, and finally,
  Dacron.

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Society for Vascular Surgery

• In 1955 expressed its concern about the big
  variety of vascular substitutes and asked for a
  opinion of the leaders of the Society.
• They, wisely, expressed no opinion at all, and
  the synthetic grafts continued to improve

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The problem of kinking of the graft was solved
by Sterling Edwards and James Trapp who
introduced the method of crimping in 1955 The
grafts we use untill today are very similar to
those developed at that time
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Grafts to replace the human aorta in aneurysmal
disease continue to develop with the works of
Juan Parodi, an Argentinian surgeon who settled
the fundamentals for endovascular surgery in this
disease. So, in selected cases, minimally invase
aortic surgery for aneurysmal disease became
possible since 1991
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Other vascular substitutes

• Gore (PTFE - expanded politetrafluoretylene)
• A superb isolative garment used for extreme
  temperatures
• C.D. Campbell used it
• as vascular substitute
• for small vessels in 1976

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The great steps

• Silk 2700 BC
• Si Ling Chi
• X rays 1895
• Wilhelm C. Roentgen (Nobel)
• Vascular surgical techniques 1912
• Alexis Carrel (Nobel)
• Heparin 1935
• Jay McLean and William Howell
• Arteriogram 1943
• Egas Muniz (Nobel)
• Synthetic artery 1952
• Voorhees, Jarelski and Blakemore
• Endovascular aortic substitute 1991
• Parodi