Yong He1, Chessy M Fernandez2, Zhihua Jiang1, Ming Tao1, Kerri A O'Malley1, Scott A Berceli3. 1. Malcom Randall VAMC, Gainesville, Fla; Division of Vascular Surgery and Endovascular Therapy, Department of Surgery, College of Medicine, University of Florida, Gainesville, Fla. 2. Malcom Randall VAMC, Gainesville, Fla; Department of Biomedical Engineering, College of Engineering, University of Florida, Gainesville, Fla. 3. Malcom Randall VAMC, Gainesville, Fla; Division of Vascular Surgery and Endovascular Therapy, Department of Surgery, College of Medicine, University of Florida, Gainesville, Fla. Electronic address: bercesa@surgery.ufl.edu.
Abstract
OBJECTIVE: After vascular interventions, unidentified mechanisms disrupt the homeostasis of a focal narrowing to initiate an intimal thickening response. We hypothesize that perturbations in the hemodynamic microenvironment are the initiating event for this disruption of homeostasis and intimal thickening in vein bypass grafts. The objective of this study was to investigate the relation between local flow perturbations and its influence on the vein graft architecture. METHODS: An external ligature was used to create an 80% focal midgraft stenosis in bilateral rabbit carotid vein grafts. A unilateral distal ligation created a ninefold difference in flow rate between high-flow and low-flow grafts. Ten vein grafts were harvested at 28 days and serially sectioned for morphologic evaluation and vein graft reconstruction. Computational fluid dynamics analyses were performed to examine the hemodynamic environment within these complex flow regions. RESULTS: The largest intimal thickening occurred exclusively within the region immediately distal to the maximum stenosis in high-flow grafts, which was characterized by persistent flow separation and reversal for the entire cardiac cycle. In regions of low to moderate shear stress (<5 Pa), the typical inverse correlation between intimal thickness and wall shear was observed. CONCLUSIONS: Regions of vein bypass grafts exposed to persistent flow reversal are most at risk for intimal thickening and loss of lumen. Published by Mosby, Inc.
OBJECTIVE: After vascular interventions, unidentified mechanisms disrupt the homeostasis of a focal narrowing to initiate an intimal thickening response. We hypothesize that perturbations in the hemodynamic microenvironment are the initiating event for this disruption of homeostasis and intimal thickening in vein bypass grafts. The objective of this study was to investigate the relation between local flow perturbations and its influence on the vein graft architecture. METHODS: An external ligature was used to create an 80% focal midgraft stenosis in bilateral rabbit carotid vein grafts. A unilateral distal ligation created a ninefold difference in flow rate between high-flow and low-flow grafts. Ten vein grafts were harvested at 28 days and serially sectioned for morphologic evaluation and vein graft reconstruction. Computational fluid dynamics analyses were performed to examine the hemodynamic environment within these complex flow regions. RESULTS: The largest intimal thickening occurred exclusively within the region immediately distal to the maximum stenosis in high-flow grafts, which was characterized by persistent flow separation and reversal for the entire cardiac cycle. In regions of low to moderate shear stress (<5 Pa), the typical inverse correlation between intimal thickness and wall shear was observed. CONCLUSIONS: Regions of vein bypass grafts exposed to persistent flow reversal are most at risk for intimal thickening and loss of lumen. Published by Mosby, Inc.
Authors: Zhihua Jiang; Lizhen Wu; Brett L Miller; Darin R Goldman; Chessy M Fernandez; Zaher S Abouhamze; C Keith Ozaki; Scott A Berceli Journal: Am J Physiol Heart Circ Physiol Date: 2003-09-18 Impact factor: 4.733
Authors: Jason L Sperry; Clayton B Deming; Ce Bian; Peter L Walinsky; David A Kass; Frank D Kolodgie; Renu Virmani; Antony Y Kim; Jeffrey J Rade Journal: Circ Res Date: 2003-01-10 Impact factor: 17.367
Authors: Jinah Hwang; Aniket Saha; Yong Chool Boo; George P Sorescu; J Scott McNally; Steven M Holland; Sergei Dikalov; Don P Giddens; Kathy K Griendling; David G Harrison; Hanjoong Jo Journal: J Biol Chem Date: 2003-09-04 Impact factor: 5.157