Comparison of the Graft Angles Effects on the Temporal Wall Shear Stress Gradients in the Aorto-Coronary and Coronary-Coronary Bypasses

Document Type: Research Note


Biomedical and Electrical Faculty, Shahand University of Technology, Tabriz, I.R. IRAN


In this theoretical study, the effect of various types of bypass graft angles on the flow field, has been investigated specially on the temporal Wall Shear Stress (WSS) on the toe, heel and some locations on the bed of the Left Anterior Descending (LAD) artery at the anastomoses areas in the Aorto-Coronary (AC) and Coronary-Coronary (CC) bypasses. Flow fields in both bypasses with angles of 20º, 30º and 40º by 75% stenosis were simulated using Fluent software. The results show high restenosis potential in the side-to-end anastomosis, heel and host artery bed in the CC bypass, and also high restenosis potential at end-to-side in comparing of the AC bypass. Effects of variable graft angles on the WSS on the upper and lower heels in the CC bypass were negligible and the length of the bed influenced by variation of the graft angle was restricted to one diameter distal to the toe in AC bypass and one diameter distal to the lower toe in the CC bypass and finally use of graft angles near 30º was of other important results.  


Main Subjects

[1] Hartman C. W., Kong Y., et al., Aortocoronary Bypass Surgery: Correlation of Angiographic, Symptomatic and Functional Improvement at 1 Year, Am. J. Cardiol., 37, p. 352 (1976).

[2] Hofer M., Rappitsch G., Perktold K., Tuble W., Schima H., Numerical Study of Wall Mechanics and Fluid Dynamics in End-to-Side Anastomoses and Correlation to Intimal Hyperplasia, J. Biomechanics 29, p. 1297 (1996).

[3] Bassiouny H.S., White S.,Glagov S.,Choi E., Giddens D.P., Zarins C. K., Anastomotic Intimal Hyperplasia: Mechanical Injury or Flow Induced, J. Vascular Surgery, 15, p. 708-717 (1992).

[4] Moringa K., Okadome K., Kuoki M., MiyazakiT., Muto Y., Inokuchi K., Effect of Arterially Transported Autogenous Vein in Dogs, J. Vascular Surgery, 2, p. 430 (1985).

[5] Rittgers S. E., Karayannacos P. E., Guy J. F., Velocity Distribution and Intimal Proliferation in Autologous Vein Grafts in Dogs, Circulation Research, 42, p. 792 (1978).

[6] Lei M., Kleinstreuer C., Trusky G., Numerical Analysis and Prediction of Atherogenic Sites in Branching Arteries, ASME J., Biomechanical Engineering, 117, p. 350 (1995).

[7] Kleinstreuer C., Lei M., Buchanan J., Archie J., Hemodynamics of Femoral Graft-Artery  Connector Mitigating Restenosis, In: Hull M. (Ed.), Proceedings of the 1995 Bioengineering Conference, BED- Vol. 31, ASME Press, New York, p. 171-172 (1995).

[8] Ojha M., Wall Shear Stress Temporal Gradient and Anastomotic Intimal Hyperplasia, Circulation Research, 7, p. 1227 (1994).

[9] Leuprecht A. et al., Numerical Study of Hemodynamics and Wall Mechanics in Distal End-to-Side Anastomoses of Bypass Grafts, J. Biomechanics, 35, p. 225 (2002).

[10] Wentzel J. J., et al., Coronary Stent Implantation Changes 3-D Vessel Geometry and 3-D Shear Stress Distribution, J. Biomechanics, 33(10), p. 1287 (2000).

[11] Loudon C., et al., The Use of the Dimensionless Womersley Number to Characterize the Unsteady Nature of Internal Flow, J. Theor. Biol., 191 (1), p. 63 (1998).

[12] Weston S.J. et al., Combined MRI and CFD Analysis of Fully Developed Steady and Pulsatile Laminar Flow through a Bend, J. Magn. Reson. Imaging, 8 (5), p. 1158 (1998).

[13] Rindt C. C., and Steenhoven A. A., Unsteady Flow in a 3-D Model of the Carotid Artery Bifurcation,
J. Biomechanical Eng., 118(1), p. 90 (1996).

[14] Ahmadlouie darab M., Simulation of Pulsatile Blood Flow in the Bypassed Coronary Arteries and study the Restenosis Reasons, MSc Thesis, Biomed. Group, Chem.Eng.Dep.,Sharif University of Technology,Tehran,Iran, Mar., (2004).

[15] Giddens D.P., Zarins C.K., Glogov S., Response of Arteries near Wall Fluid Dynamic Behavior, Appl. Mech. Rev., 43, p. 98 (1990).