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Eur J Cardiothorac Surg 2004;26:248-256
© 2004 Elsevier Science NL
a Laboratory of Thermodynamics in Emerging Technologies, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
b Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland
c Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
Received 10 October 2003; received in revised form 23 January 2004; accepted 4 February 2004.
* Corresponding author. Address: D Hoer 45, Secretariat, Clinic for Cardiovascular Surgery, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland. Tel.: +41-1-255-1111; fax: +41-1-255-4467
e-mail: dave.hitendu{at}usz.ch
Objective: To assess the feasibility of computationally simulating intracoronary blood flow based on real coronary artery geometry and to graphically depict various mechanical characteristics of this flow. Methods: Explanted fresh pig hearts were fixed using a continuous perfusion of 4% formaldehyde at physiological pressures. Omnipaque dye added to lead rubber solution was titrated to an optimum proportion of 1:25, to cast the coronary arterial tree. The heart was stabilized in a phantom model so as to suspend the base and the apex without causing external deformation. High resolution computerized tomography scans of this model were utilized to reconstruct the three-dimensional coronary artery geometry, which in turn was used to generate several volumetric tetrahedral meshes of sufficient density needed for numerical accuracy. The transient equations of momentum and mass conservation were numerically solved by employing methods of computational fluid dynamics under realistic pulsatile inflow boundary conditions. Results: The simulations have yielded graphic distributions of intracoronary flow stream lines, static pressure drop, wall shear stress, bifurcation mass flow ratios and velocity profiles. The variability of these quantities within the cardiac cycle has been investigated at a temporal resolution of 1/100th of a second and a spatial resolution of about 10 µm. The areas of amplified variations in wall shear stress, mostly evident in the neighborhoods of arterial branching, seem to correlate well with clinically observed increased atherogenesis. The intracoronary flow lines showed stasis and extreme vorticity during the phase of minimum coronary flow in contrast to streamlined undisturbed flow during the phase of maximum flow. Conclusions: Computational tools of this kind along with a state-of-the-art multislice computerized tomography or magnetic resonance-based non-invasive coronary imaging, could enable realistic, repetitive, non-invasive and multidimensional quantifications of the effects of stenosis on distal hemodynamics, and thus help in precise surgical/interventional planning. It could also add insights into coronary and bypass graft atherogenesis.
Key Words: Atherogenesis Coronary flow Computational flow simulation Non-invasive coronary imaging Surgical planning
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