EVOLUTION OF VASCULAR SUBSTITUTES

Prof. Dr. Bonno van BellenChief of the Department for Vascular

Surgery and Angiology the Beneficencia Portuguesa Hospital of São Paulo

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

Seated on her chair, a cocoon felt in her cup She unraveled the tiny threads that formed the cocoon, made bya small white caterpillar

She discovered silkDiscovery was keps secret untill the year

300DC

• Silk was China´s 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

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

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

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

• 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

• Some technique to “see” the blood vessels had to be discovered

• Some way to impede clotting of blood had to be discovered

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

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

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.

• We had the fundamentals of the vascular surgical techniques - Carrel

• We had the ways to “see” the arterial disease - Roentgen > Moniz

• We had heparin making direct access to the blood vessels possible without clotting > McLean and Howell

• 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 1940’s by Robert Gross in Boston

• 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

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

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 135:332, 1952

Ann Surg 135:332, 1952

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.

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

The problem of kinking of the graft was solved by Sterling Edwards andJames Trapp who introduced the method of crimping in 1955 The grafts we use untill today are very similar to those developed at that time

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

Other vascular substitutes

• Gore (PTFE - expanded politetrafluoretylene)– A superb isolative garment used for

extreme temperatures– C.D. Campbell used itas vascular substitute for small vessels in 1976

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