The Influence of Strut-Connectors in Stented Vessels: A Comparison of Pulsatile Flow Through Five Coronary Stents
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The design of coronary stents has evolved significantly over the past two decades. However, they still face the problem of in-stent restenosis, formation of neointima within 12 months of the implant. The biological response after stent implantation depends on various factors including the stent geometry which alters the hemodynamics. This study takes five different coronary stent designs, used in clinical practice, and explores the hemodynamic differences arising due to the difference in their design. Of particular interest is the design of the segments (connectors) that connect two struts. Pulsatile blood flow analysis is performed for each stent, using 3-D computational fluid dynamics (CFD), and various flow features viz. recirculation zones, velocity profiles, wall shear stress (WSS) patterns, and oscillatory shear indices are extracted for comparison. Vessel wall regions with abnormal flow features, particularly low, reverse, and oscillating WSS, are usually more susceptible to restenosis. Unlike previous studies, which have tried to study the effect of design parameters such as strut thickness and strut spacing on hemodynamics, this work investigates the differences in the flow arising purely due to differences in stent-shape, other parameters being similar. Two factors, the length of the connectors in the cross-flow direction and their alignment with the main flow, are found to affect the hemodynamic performance. This study also formulates a design index (varying from 18.81% to 24.91% for stents used in this study) that quantifies the flow features that could affect restenosis rates and which, in future, could be used for optimization studies.
KeywordsStents Restenosis Computational fluid dynamics Coronary artery Pulsatile blood flow
Computational fluid dynamics
Wall shear stress
Coronary artery disease
Bare metal stents
Drug eluting stents
Laser doppler velocimeter
Left anterior descending
Finite element analysis
Non-uniform rational B-splines
Modified oscillatory shear index
Hemodynamic low and reverse flow index
Conflict of Interest
Pant, Bressloff, and Forrester have no financial relationships with any organizations that could influence this work. Curzen is involved in unrestricted research grants with Medtronic and Medicell. He also advises Medtronic, Boston Scientific, Cordis, Abbott, and Lilly.
- 1.Anderson, R., F. Fath-Ordoubadi, S. Younas, A. Bainbridge, R. Swallow, K. D. Dawkins, and N. P. Curzen. Drug-eluting stents for the treatment of in stent restenosis—“real world” double centre experience in consecutive patients. Int. J. Cardiovasc. Interv. 7:188–192, 2005.Google Scholar
- 8.DePaola, N., M. A. Gimbrone, P. F. Davies, and C. F. Dewey Jr. Vascular endothelium responds to fluid shear stress gradients. Arterioscler. Thromb. Vasc. Biol. 12:1254–1257, 1992.Google Scholar
- 12.Henry, F. S. Flow in stented arteries. In: Intra- and Extracorporeal Cardiovascular Fluid Dynamics, Vol. 2, edited by P. Vendonck and K. Perktold. Southampton, UK: WIT Press, 2000, pp. 333–364.Google Scholar
- 13.Hobson, A., and N. Curzen. Improving outcomes with antiplatelet therapies in percutaneous coronary intervention and stenting. Thromb. Haemostasis. 101:23–30, 2009.Google Scholar
- 15.Kastrati, A., J. Mehilli, J. Dirschinger, F. Dotzer, H. Schuhlen, F. J. Neumann, M. Fleckenstein, C. Pfafferott, M. Seyfarth, and A. Schomig. Intracoronary stenting and angiographic results: strut thickness effect on restenosis outcome (ISAR-STEREO) trial. Circulation 103:2816–2821, 2001.PubMedGoogle Scholar
- 18.Ku, D. N., C. K. Zarins, D. P. Giddens, and S. Glagov. Pulsatile flow and atherosclerosis in the human carotid bifurcation: positive correlation between plaque localization and low and oscillating shear stress. Arteriosclerosis 5:292–302, 1985.Google Scholar
- 19.LaDisa Jr., J. F., I. Guler, L. E. Olson, D. A. Hettrick, J. R. Kersten, D. C. Warltier, and P. S. Pagel. Three-dimensional computational fluid dynamics modeling of alterations in coronary wall shear stress produced by stent implantation. Ann. Biomed. Eng. 31:972–980, 2003.CrossRefPubMedGoogle Scholar
- 20.LaDisa Jr., J. F., G. Ismail, L. E. Olson, S. H. Audi, D. A. Hettrick, J. R. Kersten, D. C. Warltier, and P. S. Pagel. Stent design properties and deployment ratio influence indexes of wall shear stress: a three-dimensional computational fluid dynamics investigation within a normal artery. J. Appl. Physiol. 97:424–430, 2004.CrossRefPubMedGoogle Scholar
- 25.Serruys, P. W. Handbook of Coronary Stents, 4th edn. Martin Dunitz Publishers, 1997.Google Scholar
- 26.Weblink. Art-stent website, 2009. http://www.art-stent.com.
- 27.Weblink. Biomatrix stent website, 2009. http://www.biomatrix.com.