Chapitre 1.D.19.4 Les prothèses en chirurgie cardiaque Chapitre 1.D.19.4.a Introduction of a flexible polymeric heart valve prosthesis with special design for aortic position 1 Historique : The first commercially available heart valve prosthesis was the Starr-Edwards mechanical valve designed for the aortic position (1961) 2 . Prior to that, at the end of the 1950s, sporadic implantation of aortic valve prostheses in humans had been performed with valves made of flexible polymers 3 . 1 . Daebritza et al., European Journal of Cardio-thoracic Surgery 25 (2004) 946–952 2 . Starr A, Edwards ML. Mitral valve replacement: clinical experience with a ball valve prosthesis. Ann Surg 1961;154:726. 3 . Roe BB, Moore D. Design and fabrication of prosthetic valves. Exper Med Surg 1958;16:167–77.
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Chapitre 1.D.19.4 Les prothèses en chirurgie
cardiaque
Chapitre 1.D.19.4.a Introduction of a flexible polymeric heart
valve prosthesis with special design for aortic position1
Historique : The first commercially available heart valve prosthesis was the
Starr-Edwards mechanical valve designed for the aortic position (1961)2. Prior
to that, at the end of the 1950s, sporadic implantation of aortic valve prostheses
in humans had been performed with valves made of flexible polymers3.
1. Daebritza et al., European Journal of Cardio-thoracic Surgery 25 (2004) 946–952
2. Starr A, Edwards ML. Mitral valve replacement: clinical experience with a ball valve
prosthesis. Ann Surg 1961;154:726. 3. Roe BB, Moore D. Design and fabrication of prosthetic valves. Exper Med Surg
1958;16:167–77.
Notre cœur est composé de quatre grandes parties : le ventricule gauche,
l'oreillette gauche, le ventricule droit et l'oreillette droite. La valve mitrale est
située entre l'oreillette et le ventricule gauche et permet au sang de passer entre
les deux. Cette valve joue un rôle majeur dans la circulation dite systémique
(vers le cerveau, les reins, etc.) puisqu'elle empêche le sang de refluer dans
l'oreillette gauche lors de la contraction ventriculaire (systole) qui expulse le
sang en dehors du ventricule gauche vers les artères. "Mais malheureusement,
dans un certain nombre de cas, cette valvule mitrale est incompétente et laisse
donc refluer du sang du ventricule gauche vers l'oreillette gauche, souligne le
Professeur Lancellotti. C'est ce que l'on appelle une insuffisance mitrale."
Current prosthetic heart valves need permanent anticoagulation or have
limited durability and impaired hemodynamic performance compared to natural
valves. Recently a polymeric valve prostheses with special design for mitral
position demonstrated excellent in vitro and in vivo results with improved
durability and no need for permanent anticoagulation.
The aortic prosthesis (ADIAMw lifescience AG, Erkelenz, Germany) is
entirely made of polycarbonaturethane. The tri-leaflet flexible prosthesis
mimicks the natural aortic valve and has a diminished pressure loss and reduced
stress and strain peaks at the commissures. The valve underwent long-term in
vitro testing and in vivotesting in a growing calve animal model (20 weeks, 7
aortic valves) and was compared to two different commercial bioprostheses.
Conclusion: The new flexible polymeric aortic valve prosthesis is
superior to current bioprostheses in animal testing.
Chapitre 1.D.19.4.b Prévention du processus de
calcification des valves5
Background : Stentless porcine aortic valve bioprostheses, which are used for
both aortic valve replacement and right ventricular bypass procedures in
congenital heart disease surgery, have provided an important alternative to stent-
mounted valves because of their more favorable characteristics including lower
pressure gradients6. It has been reported that these devices enhance patient
survival rate as a consequence of improved flow characteristics and restoration
of left ventricular function 7,8. Unfortunately, calcification of the aortic wall in
the root segment of stentless bioprosthetic valves remains a problem 9.
Dystrophic calcification is the most frequent contributing factor to
the failure of glutaraldehyde-fixed bioprosthetic valves1011
, resulting in stenosis
and/or regurgitation, and subsequent valve replacement.
5. Clark et al., Prevention of Calcification of Bioprosthetic Heart Valve Cusp and Aortic Wall
With Ethanol and Aluminum Chloride, Ann Thorac Surg 2005;79:897–904. 6. David TE, Feindel CM, Scully HE, Bos J, Rakowski H. Aortic valve replacement with
stentless porcine aortic valves: a ten-year experience. J Heart Valve Dis 1998;7:250–4. 7. Westaby S. Stentless bioprostheses in aortic root disease. Semin Thorac Cardiovasc Surg
2001;13:273– 82. 8 Westaby S, Horton M, Jin XY, et al. Survival advantage of stentless aortic bioprotheses.
Ann Thorac Surg 2000;70:785–91. 9. Herijgers P, Ozaki S, Verbeken E, et al. Calcification characteristics of porcine stentless
valves in juvenile sheep. Eur J Cardiothorac Surg 1999;15:134–42. 10
. Schoen FJ, Kujovich JL, Levy RJ, St. John Sutton M. Bioprosthetic heart valve pathology:
clinicopathologic features of valve failure and pathobiology of calcification. Cardiovasc Clin
1988;18:289 –317. 11
. Schoen FJ, Levy RJ, Piehler HR. Pathological considerations in replacement cardiac
valves. Cardiovasc Pathol 1992;1:29–52.
Hypothèse de travail : It was hypothesized that differential pretreatment
with ethanol-aluminum chloride will prove safe and efficacious for inhibiting
the calcification of both the porcine aortic valve bioprosthetic cusp and the
aortic wall.
Méthodes : Glutaraldehyde-fixed porcine aortic valves were subjected to
differential aluminum chloride (AlCl3) and ethanol pretreatment; aortic wall
segments were treated exclusively with AlCl3 (0.1 moles/L) for 45 minutes, 6
hours, or 8 hours (groups 3A, B, and C, respectively), followed by valve cusp
incubations in ethanol (80%, pH 7.4). Nontreated control bioprosthetic valves
were either stent-mounted porcine aortic valve bioprostheses (Carpentier-
Edwards, group 1) (Edwards, Santa Anna, CA) or St. Jude Toronto SPV valves
(St. Jude Medical, St. Paul, MN) (group 2). Mitral valve replacements were
carried out in juvenile sheep for 150 days.
Toxicité : Aluminum Evaluation
Aluminum levels were measured in both the bioprosthetic cusp and aortic
wall of control and aluminum chloride treated valves. In the control (groups 1
and 2)and group 3A cusps, aluminum levels were extremely low, while valves
subjected to aluminum chloride for 6 hours and 8 hours showed higher amounts
(Fig 7).
Indeed, differential pretreatment for 6 hours demonstrated significantly
increased Al levels compared to group 3A (p _ 0.006). As expected, aluminum
levels in the aortic wall were significantly greater for all differentially treated
valves compared to control glutaraldehyde-fixed valves (Fig 8).
Chapitre 1.D.19.4.c Caractérisation des microcalcifications pathologiques de
valves aortiques12
La valve qui subit la pression la plus forte est la valve aortique. C’est elle
qui est le plus souvent calcifiée. La valve mitrale est peu souvent calcifiée alors
que la valve tricuspide et la valve pulmonaire ne le sont quasiment jamais.
12
. Stage de licence LIII physique et matériaux,
Echantillonage
Spectroscopie Infra Rouge
Chapitre 1.D.19.4.d Polyester vascular prostheses coated with a
cyclodextrin polymer and activated with antibiotics: Cytotoxicity and
microbiological evaluation13
Polyester (polyethyleneterephtalate, PET) vascular grafts are used to
replace or bypass damaged arteries.
14
Principal défaut : One of the major adverse outcomes following PET
grafts implantation is infection, diagnosed in one person per year and per
100,000 residents.
This amounts to about 350 patients every year in France (6% of the
annual surgical procedures).
13
. Blanchemain et al., Acta Biomaterialia 4 (2008) 1725–1733 14