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Wang H, Fan L, Choy JS, Kassab GS, Lee LC. Simulation of coronary capillary transit time based on full vascular model of the heart. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 243:107908. [PMID: 37931581 PMCID: PMC10872892 DOI: 10.1016/j.cmpb.2023.107908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/24/2023] [Accepted: 10/30/2023] [Indexed: 11/08/2023]
Abstract
Capillary transit time (CTT) is a fundamental determinant of gas exchange between blood and tissues in the heart and other organs. Despite advances in experimental techniques, it remains difficult to measure coronary CTT in vivo. Here, we developed a novel computational framework that couples coronary microcirculation with cardiac mechanics in a closed-loop system that enables prediction of hemodynamics in the entire coronary network, including arteries, veins, and capillaries. We also developed a novel "particle-tracking" approach for computing CTT where "virtual tracers" are individually tracked as they traverse the capillary network. Model predictions compare well with blood pressure and flow rate distributions in the arterial network reported in previous studies. Model predictions of transit times in the capillaries (1.21 ± 1.5 s) and entire coronary network (11.8 ± 1.8 s) also agree with measurements. We show that, with increasing coronary artery stenosis (as quantified by fractional flow reserve, FFR), intravascular pressure and flow rate downstream are reduced but remain non-stationary even at 100 % stenosis because some flow (∼3 %) is redistributed from the non-occluded to the occluded territories. Importantly, the model predicts that occlusion of a large artery results in higher CTT. For moderate stenosis (FFR > 0.6), the increase in CTT (from 1.21 s without stenosis to 2.23 s at FFR=0.6) is caused by a decrease in capillary flow rate. In severe stenosis (FFR = 0.1), the increase in CTT to 14.2 s is due to both a decrease in flow rate and an increase in path length taken by "virtual tracers" in the capillary network.
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Affiliation(s)
- Haifeng Wang
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA.
| | - Lei Fan
- The Joint Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jenny S Choy
- California Medical Innovations Institute, San Diego, California, USA
| | - Ghassan S Kassab
- California Medical Innovations Institute, San Diego, California, USA
| | - Lik Chuan Lee
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA
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Kang YJ. Biomechanical Investigation of Red Cell Sedimentation Using Blood Shear Stress and Blood Flow Image in a Capillary Chip. MICROMACHINES 2023; 14:1594. [PMID: 37630130 PMCID: PMC10456426 DOI: 10.3390/mi14081594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/01/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023]
Abstract
Blood image intensity has been used to detect erythrocyte sedimentation rate (ESR). However, it does not give information on the biophysical properties of blood samples under continuous ESR. In this study, to quantify mechanical variations of blood under continuous ESR, blood shear stress and blood image intensity were obtained by analyzing blood flows in the capillary channel. A blood sample is loaded into a driving syringe to demonstrate the proposed method. The blood flow rate is set in a periodic on-off pattern. A blood sample is then supplied into a capillary chip, and microscopic blood images are captured at specific intervals. Blood shear stress is quantified from the interface of the bloodstream in the coflowing channel. τ0 is defined as the maximum shear stress obtained at the first period. Simultaneously, ESRτ is then obtained by analyzing temporal variations of blood shear stress for every on period. AII is evaluated by analyzing the temporal variation of blood image intensity for every off period. According to the experimental results, a shorter period of T = 4 min and no air cavity contributes to the high sensitivity of the two indices (ESRτ and AII). The τ0 exhibits substantial differences with respect to hematocrits (i.e., 30-50%) as well as diluents. The ESRτ and AII showed a reciprocal relationship with each other. Three suggested properties represented substantial differences for suspended blood samples (i.e., hardened red blood cells, different concentrations of dextran solution, and fibrinogen). In conclusion, the present method can detect variations in blood samples under continuous ESR effectively.
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Affiliation(s)
- Yang Jun Kang
- Department of Mechanical Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
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Hyakutake T, Tsutsumi Y, Miyoshi Y, Yasui M, Mizuno T, Tateno M. Red Blood Cell Partitioning Using a Microfluidic Channel with Ladder Structure. MICROMACHINES 2023; 14:1421. [PMID: 37512732 PMCID: PMC10385109 DOI: 10.3390/mi14071421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023]
Abstract
This study investigated the partitioning characteristics of red blood cells (RBCs) within capillaries, with a specific focus on ladder structures observed near the end of the capillaries. In vitro experiments were conducted using microfluidic channels with a ladder structure model comprising six bifurcating channels that exhibited an anti-parallel flow configuration. The effects of various factors, such as the parent channel width, distance between branches, and hematocrit, on RBC partitioning in bifurcating channels were evaluated. A decrease in the parent channel width resulted in an increase in the heterogeneity in the hematocrit distribution and a bias in the fractional RBC flux. Additionally, variations in the distance between branches affected the RBC distribution, with smaller distances resulting in greater heterogeneity. The bias of the RBC distribution in the microchannel cross section had a major effect on the RBC partitioning characteristics. The influence of hematocrit variations on the RBC distribution was also investigated, with lower hematocrit values leading to a more pronounced bias in the RBC distribution. Overall, this study provides valuable insights into RBC distribution characteristics in capillary networks, contributing to our understanding of the physiological mechanisms of RBC phase separation in the microcirculatory system. These findings have implications for predicting oxygen heterogeneity in tissues and could aid in the study of diseases associated with impaired microcirculation.
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Affiliation(s)
- Toru Hyakutake
- Faculty of Engineering, Yokohama National University, 79-5 Hodogaya, Yokohama 240-8501, Japan
| | - Yuya Tsutsumi
- Graduate School of Engineering Science, Yokohama National University, 79-5 Hodogaya, Yokohama 240-8501, Japan
| | - Yohei Miyoshi
- Graduate School of Engineering Science, Yokohama National University, 79-5 Hodogaya, Yokohama 240-8501, Japan
| | - Manabu Yasui
- Kanagawa Institute of Industrial Science and Technology, 705-1 Shimoimaizumi, Ebina 243-0435, Japan
| | - Tomoki Mizuno
- Graduate School of Engineering Science, Yokohama National University, 79-5 Hodogaya, Yokohama 240-8501, Japan
| | - Mizuki Tateno
- College of Engineering Science, Yokohama National University, 79-5 Hodogaya, Yokohama 240-8501, Japan
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Rashidi Y, Simionato G, Zhou Q, John T, Kihm A, Bendaoud M, Krüger T, Bernabeu MO, Kaestner L, Laschke MW, Menger MD, Wagner C, Darras A. Red blood cell lingering modulates hematocrit distribution in the microcirculation. Biophys J 2023; 122:1526-1537. [PMID: 36932676 PMCID: PMC10147840 DOI: 10.1016/j.bpj.2023.03.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 02/04/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
The distribution of red blood cells (RBCs) in the microcirculation determines the oxygen delivery and solute transport to tissues. This process relies on the partitioning of RBCs at successive bifurcations throughout the microvascular network, and it has been known since the last century that RBCs partition disproportionately to the fractional blood flow rate, therefore leading to heterogeneity of the hematocrit (i.e., volume fraction of RBCs in blood) in microvessels. Usually, downstream of a microvascular bifurcation, the vessel branch with a higher fraction of blood flow receives an even higher fraction of RBC flux. However, both temporal and time-average deviations from this phase-separation law have been observed in recent studies. Here, we quantify how the microscopic behavior of RBC lingering (i.e., RBCs temporarily residing near the bifurcation apex with diminished velocity) influences their partitioning, through combined in vivo experiments and in silico simulations. We developed an approach to quantify the cell lingering at highly confined capillary-level bifurcations and demonstrate that it correlates with deviations of the phase-separation process from established empirical predictions by Pries et al. Furthermore, we shed light on how the bifurcation geometry and cell membrane rigidity can affect the lingering behavior of RBCs; e.g., rigid cells tend to linger less than softer ones. Taken together, RBC lingering is an important mechanism that should be considered when studying how abnormal RBC rigidity in diseases such as malaria and sickle-cell disease could hinder the microcirculatory blood flow or how the vascular networks are altered under pathological conditions (e.g., thrombosis, tumors, aneurysm).
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Affiliation(s)
- Yazdan Rashidi
- Experimental Physics, Saarland University, Saarbruecken, Germany.
| | - Greta Simionato
- Experimental Physics, Saarland University, Saarbruecken, Germany; Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Qi Zhou
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom
| | - Thomas John
- Experimental Physics, Saarland University, Saarbruecken, Germany
| | - Alexander Kihm
- Experimental Physics, Saarland University, Saarbruecken, Germany
| | - Mohammed Bendaoud
- Experimental Physics, Saarland University, Saarbruecken, Germany; Université Grenoble Alpes, CNRS, LIPhy, Grenoble, France; LaMCScI, Faculty of Sciences, Mohammed V University of Rabat, Rabat, Morocco
| | - Timm Krüger
- School of Engineering, Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh, United Kingdom
| | - Miguel O Bernabeu
- Centre for Medical Informatics, Usher Institute, University of Edinburgh, Edinburgh, United Kingdom; The Bayes Centre, University of Edinburgh, Edinburgh, United Kingdom
| | - Lars Kaestner
- Experimental Physics, Saarland University, Saarbruecken, Germany; Theoretical Medicine and Biosciences, Saarland University, Homburg, Germany
| | - Matthias W Laschke
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Michael D Menger
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Christian Wagner
- Experimental Physics, Saarland University, Saarbruecken, Germany; Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg, Luxembourg
| | - Alexis Darras
- Experimental Physics, Saarland University, Saarbruecken, Germany.
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