Ulrich Sigwart
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Ulrich Sigwart (born March 9, 1941 in Wuppertal, Germany) is a cardiologist known for his pioneering role in the conception and clinical use of vascular stents.
"Professor Ulrich Sigwart was central to the greatest revo- lution in interventional cardiology since Andreas Gruentzig founded the specialty with the introduction of percutaneous transluminal coronary angioplasty (PTCA). He has been credited with the concept and realization of endoluminal stenting, a procedure that has revolutionized coronary and peripheral arterial revascularization, and also enabled the percutaneous catheter approach to carotid artery stenoses and other techniques requiring stenting." [1]
Biography
He was born in Germany on March 9, 1941, and was the fifth child of August R. Sigwart, a scientist who worked for Bayer Industries, and his wife Elizabeth. Sigwart has his origins in Tübingen (Germany) where - for several centuries - his family played an important role at the local university. Most of his father’s ancestors were doctors, philosophers, or theologians, and a street in Tübingen is named after one of them.
He had his medical education in Freiburg (Germany), Basel (Switzerland) and Munster (Germany). After some years in the U.S. (Boston and Houston) followed by additional training in Zurich (Switzerland) he was charged in 1973 to set up an invasive cardiology program at the Gollwitzer-Meier Institute in Bad Oeynhausen in Germany, which became the nidus for Heart and Diabetes Center North-Rhine Westphalia. From 1979 to 1989 he headed the section of invasive cardiology at the University Hospital in Lausanne (Switzerland). From 1989 to 2001 he was director of the department of invasive cardiology at the Royal Brompton Hospital in London and occupied the chair of cardiology at the University of Geneva (Switzerland) until his retirement in 2006.
Sigwart believed in the concept of intravascular scaffolding. In 1987, after several years of preliminary work in animals, he published a landmark paper on the use intravascular stents in humans to prevent occlusion and re-stenosis after angioplasty of coronary and peripheral arteries.[2] In 1994 he introduced percutaneous alcohol septal ablation (ASA, TASH, PTSMA), a non-surgical method for the treatment of hypertrophic obstructive cardiomyopathy, which often allows symptomatic patients to avoid open heart surgery.[3] During the years 1974–1978 he created the basis for the automated analysis of hemodynamic data and studied the repercussions of myocardial ischemia (Sigwart curve)[4] and the performance of artificial heart valves.
Ulrich Sigwart's place in the history of arterial stenting
"Following on from the ground-breaking successes of coronary angioplasty developed by Andreas Gruentzig who sadly died in a plane crash in 1985, even more inventive methods for dealing with the problem of arterial plaques have been trialled and developed. Many such trials have allowed comparison between angioplasty techniques and bypass surgery, and several new and refined devices for angioplasty have appeared. One such device was the double-lumen catheter through which on one side a motor driven cutter could be used to actually shave plaque from the arterial lumen. Other devices include the rotablater which is a high-speed rotating, pulverizing device which, by employing a vacuum system, aspirates the shaved plaque segments back into the shaft of the equipment. There have also been several laser devices and we have now moved on to the use of endoluminal stents to act as a form of ‘scaffolding’ to improve procedural success, prevent restenosis and to help prevent any possible acute vessel closure following balloon angioplasty procedures.
Woven mesh stent
The concept of employing vascular stents was first introduced by Charles Dotter in a paper written in 1964 in which he expressed the view that: ‘Once a pathway has been created across the occluded segment, repeated dilatation or the temporary use of a Silastic endovascular (or, in some cases paravascular) splint could maintain an adequate false lumen until natural processes of fibrosis and re-intimalization has taken place.
Dotter went on to experiment in 1969 with stainless steel and later in 1983 with Nitinol coils inserted into the peripheral arteries of dogs with somewhat mixed results. Later in the 1980s, three more stent designs appeared, the first designed rather like a spring in that its diameter size could be constrained and later expanded to fit the necessary pre-determined arterial size on removal of the constraint. Self expanding mesh stent
Self expanding mesh stent
Thermal memory stents provided a further design consideration: made from the metal Nitinol such stents were capable of expansion from small to a large diameter on warming to body temperature.
Julio Palmaz and colleagues experimented with balloon expandable stents based on the concept of the deformation of metal beyond its elastic limit, thus negating any possibility of later collapse. The Palmaz design had certain positive features including ease of delivery and a minimal amount of metal in its surface area after expansion. The early self-expanding stents were not without problems, however, as they were plagued by stent migration and geometric instability; perfection is never that easily achieved!
In these various stent designs, cellular and histology responses demonstrated that with maintenance of the arterial outflow, there followed a mild formation of thrombus, fibroblast proliferation, and a growth of viable endothelium. Before moving on to human trials, Palmaz and colleagues decided that it was important to test the thrombogenicity of the stents particularly since the initial thrombus deposit would undoubtedly influence later neointimal growth. In animal studies, they found that those animals treated with aspirin, dipyridamole, heparin, and dextran showed appreciably less thrombus than was found in stents from a control group that had been given various combinations of such drugs.
In a paper published in ‘Circulation’ in 1989, Richard Schatz, MD, Director of Research and Education at the Arizona Heart Institute Foundation, pointed out that the ‘success of a vascular stent should depend on minimal thrombosis and rapid endothelialisation’.2 He went on to stress that ‘because endothelium cannot grow on bare metal but can develop on a thin layer of fibrin and thrombus, thrombosis is essential for healing but it must be controlled’.
Andreas Gruentzig had recognized the problem of restenosis after angioplasty and the need for a suitable form of coronary stenting in the hope of reducing or preventing this problem. The first human implants of such vascular stents were undertaken and reported by Ulrich Sigwart. These vascular stents implanted in peripheral and coronary circulation were multi-filament self-expanding, spring-like devices and thus Sigwart became the next link in the chain initiated by Gruentzig's revolutionary developments in angioplasty, and at last, the concept of overcoming coronary stenosis percutaneously rather than by the very invasive bypass surgery might be realized.
Stent Delivery
Professor Ulrich Sigwart in 1973 Sigwart returned to Europe. After a spell of additional training at University Hospital, Zurich, he was recruited to Bad Oeynhausen, Germany, where he set up an invasive cardiology programme. He then moved to Lausanne, Switzerland, where at the University Hospital between 1979 and 1989, he played an important role in the concept and development of coronary stenting.
Sigwart's early stenting work received great interest and many travelled to Lausanne to observe the technique in practice. In a 1987 paper entitled ‘Intravascular stents to prevent occlusion and restenosis after transluminal angioplasty’, Sigwart et al. gave an interesting account of the clinical use of stents to prevent occlusion and restenosis. Sigwart's work also provided him with an opportunity to observe the outcomes and indeed the shortcomings resulting from stent therapy.
The agony and the ecstasy …
One such case was that of a patient who, 3 months after implantation in the proximal left anterior descending artery, developed severe chest pain and angiography showed severe restenosis. Sigwart urged the surgeon to remove the stented segment and reported how ‘Gazing at the massive tissue obstructing the stent lumen, the hypothesis of mechanical support for the prevention of restenosis looked like an illusion and that a combination of mechanical and biologic factors would be the sine qua non to overcome the problem of recurrence.
In 1989, Sigwart took up the directorship of the Department of Invasive Cardiology at the Royal Brompton Hospital in London, England, and during his 12-year tenure at this post, he put forward the first plan aimed at comparing percutaneous coronary intervention employing stents with the relatively well-accepted coronary bypass surgery. As with all procedures, there are ‘pros’ and ‘cons’, and in this case, the research and questions remain ongoing." (Diana Berry,Oxford Journals, Medicine, European Heart Journal, Volume 30, Issue 14, Pp. 1677-1686.) [5]
Awards
European Society of Cardiology Medal 1996,
ESC Andreas Gruentzig Award 1996,
Doctor honoris causa of the University of Lausanne 1999,
Werner Forssmann Prize 2001,
Sven Effert Prize 2003,
King Faisal International Prize for Medicine 2004,
Swiss Cardiac Society Grüntzig Award 2006,
Polzer Prize of the European Academy of Sciences and Arts 2007,
American College of Cardiology Maseri-Florio International Award 2007
American College of Cardiology Paul Dudley White Award 2012
American College of Cardiology Distinguished Scientist Award 2013
Books
U. Sigwart Automation in Cardiac Diagnosis: The Computer-Assisted Acquisition of Cardiac Catheterization Data, Schwabe 1978,
U. Sigwart and P. H. Heintzen (Editors): Ventricular Wall Motion, Thieme 1984,
U. Sigwart and G. I. Frank (Editors): Coronary Stents, Springer 1992 (ISBN 10: 0387545417, ISBN 13: 9780387545417) (Coronary Stents)
U. Sigwart: Endoluminal Stenting, W. B. Saunders 1996 (ISBN 10: 070202046X / ISBN 13: 9780702020469) (Endoluminal Stenting)
Ulrich Sigwart, Michel Bertrand, Patrick W. Serruys (Editors): Handbook on Cardiovascular Interventions, Churchill Livingstone, 1996
References
- ^ http://onlinelibrary.wiley.com/doi/10.1002/clc.20322/pdf
- ^ Sigwart U, Puel J, Mirkovitch V, Joffre F, Kappenberger L: Intravascular stents to prevent occlusion and restenosis after transluminal angioplasty. N Engl J Med 1987;316:701–706
- ^ Sigwart U: Non-surgical myocardial reduction for hypertrophic obstructive myocardial infarction. Lancet 1995;346:211–214
- ^ Sigwart U, Grbic M, Payot M, Goy J-J, Essinger A, et al.: Ischemic events during coronary artery balloon occlusion. In: Rutishauser W, Roskamm H, eds. Silent Myocardial Ischemia. Berlin: SpringerVerlag; 1984; 29–36
- ^ http://eurheartj.oxfordjournals.org/content/30/14/1677.full