Posts tagged: bioengineering

Cardiovascular Research Symposium /03 May 2011

Cardiovascular Research Conference 2011

- 03 May 2011

Eindhoven- Netherland

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Computer-Aided Patient-Specific Coronary Artery Graft Design Improvements Using CFD Coupled Shape Optimizer

Onur Dur, Sinan Tolga Coskun, Kasim Oguz Coskun, David Frakes, Levent Burak Kara and Kerem Pekkan

This study aims to (i) demonstrate the efficacy of a new surgical planning framework for complex cardiovascular reconstructions, (ii) develop a computational fluid dynamics (CFD) coupled multi-dimensional shape optimization method to aid patient-specific coronary artery by-pass graft (CABG) design and, (iii) compare the hemodynamic efficiency of the sequential CABG, i.e., raising a daughter parallel branch from the parent CABG in patient-specific 3D settings. Hemodynamic efficiency of patient-specific complete revascularization scenarios for right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) bypasses were investigated in comparison to the stenosis condition. Multivariate 2D constraint optimization was applied on the left internal mammary artery (LIMA) graft, which was parameterized based on actual surgical settings extracted from 2D CT slices. The objective function was set to minimize the local variation of wall shear stress (WSS) and other hemodynamic indices (energy dissipation, flow deviation angle, average WSS, and vorticity) that correlate with performance of the graft and risk of re-stenosis at the anastomosis zone. Once the optimized 2D graft shape was obtained, it was translated to 3D using an in-house ?sketch-based? interactive anatomical editing tool. The final graft design was evaluated using an experimentally validated second-order non-Newtonian CFD solver incorporating resistance based outlet boundary conditions. 3D patient-specific simulations for the healthy coronary anatomy produced realistic coronary flows. All revascularization techniques restored coronary perfusions to the healthy baseline. Multi-scale evaluation of the optimized LIMA graft enabled significant wall shear stress gradient (WSSG) relief (~34%). In comparison to original LIMA graft, sequential graft also lowered the WSSG by 15% proximal to LAD and diagonal bifurcation. The proposed sketch-based surgical planning paradigm evaluated the selected coronary bypass surgery procedures based on acute hemodynamic readjustments of aorta-CA flow. This methodology may provide a rational to aid surgical decision making in time-critical, patient-specific CA bypass operations before in vivo execution.

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Inverse Problems in Science and Engineering

A meshless CFD approach for evolutionary shape optimization of bypass grafts anastomoses

Improving the blood flow or hemodynamics in the synthetic bypass graft end-to-side distal anastomosis (ETSDA) is an important element for the long-term success of bypass surgeries. An ETSDA is the interconnection between the graft and the operated-on artery. The control of hemodynamic conditions through the ETSDA is mostly dictated by the shape of the ETSDA. Thus, a formal ETSDA shape optimization would serve the goal of improving the ETSDA flowfield. Computational fluid dynamics (CFD) is a convenient tool to quantify hemodynamic parameters; also, the genetic algorithm (GA) is an effective tool to identify the ETSDA optimal shape that modify those hemodynamic quantities such that the optimization objective is met. The present article introduces a unique approach where a meshless CFD solver is coupled to a GA for the purpose of optimizing the ETSDA shape. Three anastomotic models are optimized herein: the conventional ETSDA, the Miller cuff ETSDA and the hood ETSDA. Results demonstrate the effectiveness of the proposed integrated optimization approach in obtaining anastomoses optimal shapes.

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Z. El Zahaba; E. Divob; A. Kassaba

Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL, USA
Department of Engineering Technology, University of Central Florida, Orlando, FL, USA


The posts will be about current news and researches about cardiovascular mechanics and biofluid dynamics in Turkey.