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Lindsey BD, Jing B, Kim S, Collins GC, Padala M. 3-D Intravascular Characterization of Blood Flow Velocity Fields with a Forward-Viewing 2-D Array. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:2560-2571. [PMID: 32616428 PMCID: PMC7429285 DOI: 10.1016/j.ultrasmedbio.2020.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 04/06/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
Risk stratification in coronary artery disease is an ongoing challenge for which few tools are available for quantifying physiology within coronary arteries. Recently, anatomy-driven computational fluid dynamic modeling has enabled the mapping of local flow dynamics in coronary stenoses, with derived parameters such as WSS exhibiting a strong capability for predicting adverse clinical events on a patient-specific basis. As cardiac catheterization is common in patients with coronary artery disease, minimally invasive technologies capable of identifying pathologic flow in situ in real time could have a significant impact on clinical decision- making. As a step toward in vivo quantification of slow flow near the arterial wall, proof-of-concept for 3-D intravascular imaging of blood flow dynamics is provided using a 118-element forward-viewing ring array transducer and a research ultrasound system. Blood flow velocity components are estimated in the direction of primary flow using an unfocused wave Doppler approach, and in the lateral and elevation directions, using a transverse oscillation approach. This intravascular 3-D vector velocity system is illustrated by acquiring real-time 3-D data sets in phantom experiments and in vivo in the femoral artery of a pig. The effect of the catheter on blood flow dynamics is also experimentally assessed in flow phantoms with both straight and stenotic vessels. Results indicate that 3-D flow dynamics can be measured using a small form factor device and that a hollow catheter design may provide minimal disturbance to flow measurements in a stenosis (peak velocity: 54.97 ± 2.13 cm/s without catheter vs. 51.37 ± 1.08 cm/s with hollow catheter, 6.5% error). In the future, such technologies could enable estimation of 3-D flow dynamics near the wall in patients already undergoing catheterization.
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Affiliation(s)
- Brooks D Lindsey
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Electrical and Computer Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA; Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA, USA.
| | - Bowen Jing
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Saeyoung Kim
- Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA, USA; Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Graham C Collins
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Muralidhar Padala
- Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA, USA; Division of Cardiothoracic Surgery, Joseph P. Whitehead Department of Surgery, Emory University School of Medicine, Atlanta, GA, USA; Structural Heart Research and Innovation Laboratory, Carlyle Fraser Heart Center at Emory University Hospital Midtown, Atlanta, GA, USA
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Cole JS, Watterson JK, O'Reilly MJG. Numerical investigation of the haemodynamics at a patched arterial bypass anastomosis. Med Eng Phys 2002; 24:393-401. [PMID: 12135648 DOI: 10.1016/s1350-4533(02)00038-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Intimal hyperplasia at arterial bypass graft anastomoses is a major factor responsible for graft failure. A revised surgical technique, incorporating a Taylor vein patch into the distal anastomosis of PTFE grafts, results in a decrease in intimal hyperplasia and improved patency rates. Numerical simulations of pulsatile, non-Newtonian blood flow through life-like femorodistal bypass models have been performed to determine whether haemodynamic benefits arise from the modified geometry of the Taylor anastomosis. In a conventional bypass, the distal anastomotic flow exhibited considerable spatial and temporal variations. Steep spatial gradients in the shearing force acted along the floor during systole. The effect of the Taylor geometry was to reduce gradually the momentum of the blood approaching the junction. Thus, flow disturbances were abated, undesirable flow separation at the toe was diminished, and a less adverse floor shear stress distribution prevailed in that case. Intimal thickening should be alleviated at the toe in the Taylor model where separation is reduced, and where the thrombogenic graft surface is replaced with a vein patch. Intimal hyperplasia on the floor may be inhibited in the Taylor model due to more favourable shear stresses. The improved flow through the patched anastomosis should contribute to its enhanced performance.
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Affiliation(s)
- J S Cole
- School of Aeronautical Engineering, The Queen's University of Belfast, Belfast BT9 5AG, Northern Ireland, UK.
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