Effects of fluid flow shear rate and surface roughness on the calcification of polymeric heart valve leaflet.

Surface defects, blood flow shear rates and mechanical stresses are contributing factors in the calcification process of polymeric devices exposed to the blood flow. A number of experiments were performed to evaluate the effect of surface defects such as roughness and cracks and flow shear rate on the calcification process of a polyurethane material used in the design of prosthetic heart valves. Results showed that polyurethane surface gets calcified and the calcification is more pronounced at the lower shear rates. Roughness and cracks both increase the calcification levels. The results also suggest very little diffusion of calcium to the subsurface indicating that calcification of a polyurethane material, is a surface phenomenon. Based on a simple peeling test, the bond strength between the calcified layer and polyurethane was found to be extremely weak, suggesting that the bonding is in the form of Van-der-Waals. A limited set of experiments with polycarbonate showed that polycarbonate is less prone to calcification compared to polyurethane (p values less than 0.05), indicating its potential application in medical devices exposed to blood flow.

[1]  C. Pieper,et al.  Comparison of survival after mitral valve replacement with biologic and mechanical valves in 1139 patients. , 2001, The Journal of thoracic and cardiovascular surgery.

[2]  W G Henderson,et al.  A comparison of outcomes in men 11 years after heart-valve replacement with a mechanical valve or bioprosthesis. Veterans Affairs Cooperative Study on Valvular Heart Disease. , 1993, The New England journal of medicine.

[3]  C. Schmidt,et al.  Acellular vascular tissues: natural biomaterials for tissue repair and tissue engineering. , 2000, Biomaterials.

[4]  Young Ha Kim,et al.  In vivo biocompatibility of sulfonated PEO-grafted polyurethanes for polymer heart valve and vascular graft. , 2006, Artificial organs.

[5]  A. Ajdari,et al.  In vitro and computational thrombosis on artificial surfaces with shear stress. , 2010, Artificial organs.

[6]  F. R. Rosendaal,et al.  Thromboembolic and Bleeding Complications in Patients With Mechanical Heart Valve Prostheses , 1994, Circulation.

[7]  W S Pierce,et al.  A polyurethane trileaflet cardiac valve prosthesis: in vitro and in vivo studies. , 1982, Transactions - American Society for Artificial Internal Organs.

[8]  M. Narkis,et al.  An unusual visual microcracking/healing phenomenon in polycarbonate at room temperature , 1982 .

[9]  C K Breuer,et al.  Tissue engineering heart valves: valve leaflet replacement study in a lamb model. , 1995, The Annals of thoracic surgery.

[10]  Frederick J Schoen,et al.  Calcification of tissue heart valve substitutes: progress toward understanding and prevention. , 2005, The Annals of thoracic surgery.

[11]  F J Schoen,et al.  Pathological considerations in replacement cardiac valves. , 1992, Cardiovascular pathology : the official journal of the Society for Cardiovascular Pathology.

[12]  F J Schoen,et al.  Calcification of bovine pericardium used in cardiac valve bioprostheses. Implications for the mechanisms of bioprosthetic tissue mineralization. , 1986, The American journal of pathology.

[13]  Scott J Hollister,et al.  Tissue-engineered heart valve prostheses: 'state of the heart'. , 2008, Regenerative medicine.

[14]  Richard A. Lange,et al.  Prosthetic heart valves. , 1996, The New England journal of medicine.

[15]  R. Levy,et al.  Initiation of mineralization in bioprosthetic heart valves: studies of alkaline phosphatase activity and its inhibition by AlCl3 or FeCl3 preincubations. , 1991, Journal of biomedical materials research.

[17]  D. J. Wheatley,et al.  A dynamicin vitro method for studying bioprosthetic heart valve calcification , 1992 .

[18]  B Glasmacher,et al.  Primary tissue failure of bioprostheses: new evidence from in vitro tests. , 2001, The Thoracic and cardiovascular surgeon.

[19]  G. Golomb,et al.  Development of a new in vitro model for studying implantable polyurethane calcification. , 1991, Biomaterials.

[20]  D. Urry,et al.  Elastin coacervate as a matrix for calcification. , 1973, Biochemical and biophysical research communications.

[21]  Ulrich Steinseifer,et al.  Polyurethane heart valves: past, present and future , 2011, Expert review of medical devices.

[22]  P. Cipriano,et al.  Calcification of Porcine Prosthetic Heart Valves: A Radiographic and Light Microscopic Study , 1982, Circulation.