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 Vascular Grafts

Vascular graft interfacial histology

  • Protein absorption.
  • Platelet adhesion.
  • Neutrophil infiltration.
  • Monocyte recruitment.
  • Endothelial cell and smooth muscle cell ingrowth.

Mechanisms of vascular graft healing

  • The role of platelets.
  • The role of macrophages.
  • The role of endothelial cells and smooth muscle cells.

Characteristics of grafts

  • Composition.
  • Porosity.
  • Durability.
  • Flexibility.
  • Compliance.

Modes of graft failure

  • Thrombogenicity.
  • Anastomotic pseudointimal hyperplasia.

Current vascular grafts

  • Aortic grafts (knitted Dacron grafts coated with albumin, gelatin or collagen, ePTFE grafts: characteristics, advantages, disadvantages).
  • Femoral-popliteal/tibial grafts (autogenous saphenous vein, ePTFE grafts, Dacron grafts, glutaraldehyde-stabilized human umbilical vein graft, homologous vein: characteristics, advantages, disadvantages).

Experimental biohybrid prostheses

  • Synthetic materials impregnated with antimicrobial agents.
  • Anticoagulant substances affixed to synthetic graft surfaces.
  • Synthetic grafts impregnated with growth factors.

Bioresorbable synthetic grafts

  • Bioserorbable grafts (polyglycolic acid, polyglactin 910, polydioxanone grafts).
  • Grafts of compound yarns containing both resorbable (polyglycolic acid, polyglactin 910, polydioxanone) and a nonresorbable (Dacron or polypropylene) material.

References

Pasquinelli G, Freyrie A, Preda P, Curti T, D'Addato M, Laschi R. Healing of prosthetic arterial grafts. Scanning Microsc 1990;4:351-362.

The healing of prosthetic arterial grafts in animals and in humans is described in this paper. New strategies and approaches, such as endothelial cell seeding, that have recently been attempted to improve the patency of synthetic vascular grafts are also outlined.

Greenwald SE, Berry CL. Improving vascular grafts: the importance of mechanical and haemodynamic properties. J Pathol 2000;190:292-299.

The importance of mechanical and hemodynamic factors for the development of intimal hyperplasia at the graft anastomotic site is analyzed in this article. Disturbed flow at the anastomosis leading to fluctuations in shear stress at the endothelium (a known cause of intimal hyperplasia in normal arteries), injury due to suturing and stress concentration at the anastomosis are explained in detail with equations, graphs and schematic representations.

Bos GW, Poot AA, Beugeling T, van Aken WG, Feijen J. Small-diameter vascular graft prostheses: current status. Arch Physiol Biochem 1998;106:100-115.

In this overview article, the strategies used to improve the patency of these small-diameter grafts, the current status in clinical trials, and further perspectives in the field of artificial vascular graft development are reviewed. It is concluded that, in view of recent developments in tissue engineering approaches, the future of small-diameter vascular prostheses looks promising.

Liu SQ. Biomechanical basis of vascular tissue engineering. Crit Rev Biomed Eng 1999;27:75-148.

Biomechanical engineering approaches can be used to reduce tensile stress and strain due to exposure to arterial blood pressure and to prevent eddy blood flow in vein grafts. In this article, the background, principles, clinical potentials, as well as the limitations of vascular biomechanical engineering are discussed.

Teebken OE, Haverich A. Tissue engineering of small diameter vascular grafts. Eur J Vasc Endovasc Surg 2002;23:475-485.

Tissue engineering, using either polymer or biological based scaffolds, represents the newest approach to overcoming limitations of small diameter prosthetic vascular grafts. This current review represents an overview about previous and contemporary studies in the field of artificial vascular conduits development regarding arterial and venous autografts, allografts, xenografts, alloplastic prostheses, and tissue engineering.

Posted June 2010