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Montino Pelagi G, Regazzoni F, Huyghe JM, Baggiano A, Alì M, Bertoluzza S, Valbusa G, Pontone G, Vergara C. Modeling cardiac microcirculation for the simulation of coronary flow and 3D myocardial perfusion. Biomech Model Mechanobiol 2024:10.1007/s10237-024-01873-z. [PMID: 38995488 DOI: 10.1007/s10237-024-01873-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 07/01/2024] [Indexed: 07/13/2024]
Abstract
Accurate modeling of blood dynamics in the coronary microcirculation is a crucial step toward the clinical application of in silico methods for the diagnosis of coronary artery disease. In this work, we present a new mathematical model of microcirculatory hemodynamics accounting for microvasculature compliance and cardiac contraction; we also present its application to a full simulation of hyperemic coronary blood flow and 3D myocardial perfusion in real clinical cases. Microvasculature hemodynamics is modeled with a compliant multi-compartment Darcy formulation, with the new compliance terms depending on the local intramyocardial pressure generated by cardiac contraction. Nonlinear analytical relationships for vessels distensibility are included based on experimental data, and all the parameters of the model are reformulated based on histologically relevant quantities, allowing a deeper model personalization. Phasic flow patterns of high arterial inflow in diastole and venous outflow in systole are obtained, with flow waveforms morphology and pressure distribution along the microcirculation reproduced in accordance with experimental and in vivo measures. Phasic diameter change for arterioles and capillaries is also obtained with relevant differences depending on the depth location. Coronary blood dynamics exhibits a disturbed flow at the systolic onset, while the obtained 3D perfusion maps reproduce the systolic impediment effect and show relevant regional and transmural heterogeneities in myocardial blood flow (MBF). The proposed model successfully reproduces microvasculature hemodynamics over the whole heartbeat and along the entire intramural vessels. Quantification of phasic flow patterns, diameter changes, regional and transmural heterogeneities in MBF represent key steps ahead in the direction of the predictive simulation of cardiac perfusion.
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Affiliation(s)
- Giovanni Montino Pelagi
- LABS, Dipartimento di Chimica, Materiali e Ingegneria Chimica Giulio Natta, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan, 20133, Italy.
| | - Francesco Regazzoni
- MOX, Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan, 20133, Italy
| | - Jacques M Huyghe
- School of Engineering, University of Limerick, Limerick, V94 T9PX, Ireland
- Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - Andrea Baggiano
- Perioperative Cardiology and Cardiovascular Imaging Department, Centro Cardiologico Monzino IRCCS, Via Carlo Parea 4, Milan, 20138, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Marco Alì
- Bracco Imaging S.p.A., Via Caduti di Marcinelle 13, Milan, 20134, Italy
- Department of Diagnostic Imaging and Stereotactic Radiosurgery, Centro Diagnostico Italiano S.p.A., Via Saint Bon 20, Milan, 20147, Italy
| | | | - Giovanni Valbusa
- Bracco Imaging S.p.A., Via Caduti di Marcinelle 13, Milan, 20134, Italy
| | - Gianluca Pontone
- Perioperative Cardiology and Cardiovascular Imaging Department, Centro Cardiologico Monzino IRCCS, Via Carlo Parea 4, Milan, 20138, Italy
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, 20134, Italy
| | - Christian Vergara
- LABS, Dipartimento di Chimica, Materiali e Ingegneria Chimica Giulio Natta, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan, 20133, Italy
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2
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Fan L, Wang H, Kassab GS, Lee LC. Review of cardiac-coronary interaction and insights from mathematical modeling. WIREs Mech Dis 2024; 16:e1642. [PMID: 38316634 PMCID: PMC11081852 DOI: 10.1002/wsbm.1642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/10/2023] [Accepted: 01/08/2024] [Indexed: 02/07/2024]
Abstract
Cardiac-coronary interaction is fundamental to the function of the heart. As one of the highest metabolic organs in the body, the cardiac oxygen demand is met by blood perfusion through the coronary vasculature. The coronary vasculature is largely embedded within the myocardial tissue which is continually contracting and hence squeezing the blood vessels. The myocardium-coronary vessel interaction is two-ways and complex. Here, we review the different types of cardiac-coronary interactions with a focus on insights gained from mathematical models. Specifically, we will consider the following: (1) myocardial-vessel mechanical interaction; (2) metabolic-flow interaction and regulation; (3) perfusion-contraction matching, and (4) chronic interactions between the myocardium and coronary vasculature. We also provide a discussion of the relevant experimental and clinical studies of different types of cardiac-coronary interactions. Finally, we highlight knowledge gaps, key challenges, and limitations of existing mathematical models along with future research directions to understand the unique myocardium-coronary coupling in the heart. This article is categorized under: Cardiovascular Diseases > Computational Models Cardiovascular Diseases > Biomedical Engineering Cardiovascular Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Lei Fan
- Joint Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Haifeng Wang
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
| | - Ghassan S Kassab
- California Medical Innovations Institute, San Diego, California, USA
| | - Lik Chuan Lee
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
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3
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Warne CM, Essajee SI, Tucker SM, Figueroa CA, Beard DA, Dick GM, Tune JD. Oxygen-sensing pathways below autoregulatory threshold act to sustain myocardial oxygen delivery during reductions in perfusion pressure. Basic Res Cardiol 2023; 118:12. [PMID: 36988670 PMCID: PMC10797605 DOI: 10.1007/s00395-023-00985-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023]
Abstract
The coronary circulation has an innate ability to maintain constant blood flow over a wide range of perfusion pressures. However, the mechanisms responsible for coronary autoregulation remain a fundamental and highly contested question. This study interrogated the local metabolic hypothesis of autoregulation by testing the hypothesis that hypoxemia-induced exaggeration of the metabolic error signal improves the autoregulatory response. Experiments were performed on open-chest anesthetized swine during stepwise changes in coronary perfusion pressure (CPP) from 140 to 40 mmHg under normoxic (n = 15) and hypoxemic (n = 8) conditions, in the absence and presence of dobutamine-induced increases in myocardial oxygen consumption (MVO2) (n = 5-7). Hypoxemia (PaO2 < 40 mmHg) decreased coronary venous PO2 (CvPO2) ~ 30% (P < 0.001) and increased coronary blood flow ~ 100% (P < 0.001), sufficient to maintain myocardial oxygen delivery (P = 0.14) over a wide range of CPPs. Autoregulatory responsiveness during hypoxemia-induced reductions in CvPO2 were associated with increases of autoregulatory gain (Gc; P = 0.033) but not slope (P = 0.585) over a CPP range of 120 to 60 mmHg. Preservation of autoregulatory Gc (P = 0.069) and slope (P = 0.264) was observed during dobutamine administration ± hypoxemia. Reductions in coronary resistance in response to decreases in CPP predominantly occurred below CvPO2 values of ~ 25 mmHg, irrespective of underlying vasomotor reserve. These findings support the presence of an autoregulatory threshold under which oxygen-sensing pathway(s) act to preserve sufficient myocardial oxygen delivery as CPP is reduced during increases in MVO2 and/or reductions in arterial oxygen content.
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Affiliation(s)
- Cooper M Warne
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - Salman I Essajee
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - Selina M Tucker
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - C Alberto Figueroa
- Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - Daniel A Beard
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, USA
| | - Gregory M Dick
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - Johnathan D Tune
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA.
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4
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Sahoo KP, Dash A, Ghosh N, Patra A, Sinha A, Khandelwal S. Simulating Stenotic Conditions of the Coronary Artery in a Lumped Parameter Model of the Cardiovascular System. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:3993-3996. [PMID: 36086231 DOI: 10.1109/embc48229.2022.9871066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Coronary flow control mechanisms maintain the average coronary blood flow (CBF) at 4% of the cardiac output (CO) in normal adults, with no prior diagnosis of coronary artery disease (CAD), under resting conditions. This paper explores a pulsatile sixth order lumped parameter (LP) model of the cardiovascular system (CVS) which utilizes the average CBF approximated from CO along with arterial blood pressure (ABP) waveform to estimate the coronary microvascular resistance using non-linear least square optimization technique. The CVS model includes a third order model of the coronary vascular bed and is shown to achieve phasic coronary flow. The coronary epicardial resistance is varied to emulate different degrees of stenosis and achieve realistic behavior of coronary microvascular resistance under these conditions.
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Munneke AG, Lumens J, Arts T, Delhaas T. A Closed-Loop Modeling Framework for Cardiac-to-Coronary Coupling. Front Physiol 2022; 13:830925. [PMID: 35295571 PMCID: PMC8919076 DOI: 10.3389/fphys.2022.830925] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/24/2022] [Indexed: 01/09/2023] Open
Abstract
The mechanisms by which cardiac mechanics effect coronary perfusion (cardiac-to-coronary coupling) remain incompletely understood. Several coronary models have been proposed to deepen our understanding of coronary hemodynamics, but possibilities for in-depth studies on cardiac-to-coronary coupling are limited as mechanical properties like myocardial stress and strain are most often neglected. To overcome this limitation, a mathematical model of coronary mechanics and hemodynamics was implemented in the previously published multi-scale CircAdapt model of the closed-loop cardiovascular system. The coronary model consisted of a relatively simple one-dimensional network of the major conduit arteries and veins as well as a lumped parameter model with three transmural layers for the microcirculation. Intramyocardial pressure was assumed to arise from transmission of ventricular cavity pressure into the myocardial wall as well as myocardial stiffness, based on global pump mechanics and local myofiber mechanics. Model-predicted waveforms of global epicardial flow velocity, as well as of intramyocardial flow and diameter were qualitatively and quantitatively compared with reported data. Versatility of the model was demonstrated in a case study of aortic valve stenosis. The reference simulation correctly described the phasic pattern of coronary flow velocity, arterial flow impediment, and intramyocardial differences in coronary flow and diameter. Predicted retrograde flow during early systole in aortic valve stenosis was in agreement with measurements obtained in patients. In conclusion, we presented a powerful multi-scale modeling framework that enables realistic simulation of coronary mechanics and hemodynamics. This modeling framework can be used as a research platform for in-depth studies of cardiac-to-coronary coupling, enabling study of the effect of abnormal myocardial tissue properties on coronary hemodynamics.
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Affiliation(s)
- Anneloes G Munneke
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
| | - Joost Lumens
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
| | - Theo Arts
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
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6
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Razavi A, Sachdeva S, Frommelt PC, LaDisa JF. Computational Assessment of Hemodynamic Significance in Patients With Intramural Anomalous Aortic Origin of the Coronary Artery Using Virtually Derived Fractional Flow Reserve and Downstream Microvascular Resistance. J Biomech Eng 2022; 144:1119460. [PMID: 34505124 DOI: 10.1115/1.4052368] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Indexed: 11/08/2022]
Abstract
Anomalous aortic origin of a coronary artery (AAOCA) is the second most common cause of sudden cardiac death in young athletes. One of the hypothesized mechanisms of ischemia in these patients is the lateral compression of the anomalous artery with an intramural or interarterial course. The presence of a narrowing in the anomalous artery will cause physiologic changes in downstream resistance that should be included for computational assessment of possible clinical ramifications. In this study, we created different compression levels, i.e., proximal narrowing, in the intramural course of a representative patient model and calculated hyperemic stenosis resistance (HSR) as well as virtual fractional flow reserve (vFFR). Models also included the effect of the distal hyperemic microvascular resistance (HMR) on vFFR. Our results agreed with similar FFR studies indicating that FFR is increased with increasing HMR and that different compression levels could have similar FFR depending on the HMR. For example, vFFR at HSR: 1.0-1.3 and HMR: 2.30 mmHg/cm/s is 0.68 and close to vFFR at HSR: 0.6-0.7 and HMR: 1.6 mmHg/cm/s, which is 0.7. The current findings suggest that functional assessment of anomalous coronary arteries through FFR should consider the vascular resistance distal to the narrowing in addition to the impact of a proximal narrowing and provides computational approaches for implementation of these important considerations.
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Affiliation(s)
- Atefeh Razavi
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53233; Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Shagun Sachdeva
- Pediatric Cardiology, Baylor College of Medicine, Houston, TX 77030
| | - Peter C Frommelt
- Department of Pediatrics, Division of Pediatric Cardiology, Medical College of Wisconsin Children's Wisconsin, Milwaukee, WI 53226
| | - John F LaDisa
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53233; Departments of Pediatrics, Cardiovascular Medicine and Physiology, Medical College of Wisconsin, Wauwatosa, WI 53226
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7
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Liu H, Soares JS, Walmsley J, Li DS, Raut S, Avazmohammadi R, Iaizzo P, Palmer M, Gorman JH, Gorman RC, Sacks MS. The impact of myocardial compressibility on organ-level simulations of the normal and infarcted heart. Sci Rep 2021; 11:13466. [PMID: 34188138 PMCID: PMC8242073 DOI: 10.1038/s41598-021-92810-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 05/25/2021] [Indexed: 11/09/2022] Open
Abstract
Myocardial infarction (MI) rapidly impairs cardiac contractile function and instigates maladaptive remodeling leading to heart failure. Patient-specific models are a maturing technology for developing and determining therapeutic modalities for MI that require accurate descriptions of myocardial mechanics. While substantial tissue volume reductions of 15-20% during systole have been reported, myocardium is commonly modeled as incompressible. We developed a myocardial model to simulate experimentally-observed systolic volume reductions in an ovine model of MI. Sheep-specific simulations of the cardiac cycle were performed using both incompressible and compressible tissue material models, and with synchronous or measurement-guided contraction. The compressible tissue model with measurement-guided contraction gave best agreement with experimentally measured reductions in tissue volume at peak systole, ventricular kinematics, and wall thickness changes. The incompressible model predicted myofiber peak contractile stresses approximately double the compressible model (182.8 kPa, 107.4 kPa respectively). Compensatory changes in remaining normal myocardium with MI present required less increase of contractile stress in the compressible model than the incompressible model (32.1%, 53.5%, respectively). The compressible model therefore provided more accurate representation of ventricular kinematics and potentially more realistic computed active contraction levels in the simulated infarcted heart. Our findings suggest that myocardial compressibility should be incorporated into future cardiac models for improved accuracy.
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Affiliation(s)
- Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - João S Soares
- Engineered Tissue Multiscale Mechanics and Modeling Laboratory, Virginia Commonwealth University, Richmond, VA, USA
| | - John Walmsley
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - David S Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - Samarth Raut
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - Reza Avazmohammadi
- Computational Cardiovascular Bioengineering Lab, Texas A&M University, College Station, TX, USA
| | - Paul Iaizzo
- Visible Heart Lab, University of Minnesota Twin Cities, Minneapolis, MN, USA
| | - Mark Palmer
- Corporate Core Technologies, Medtronic, Inc., Minneapolis, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA.
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8
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McCallinhart PE, Scandling BW, Trask AJ. Coronary remodeling and biomechanics: Are we going with the flow in 2020? Am J Physiol Heart Circ Physiol 2020; 320:H584-H592. [PMID: 33185115 DOI: 10.1152/ajpheart.00634.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Under normal conditions, coronary blood flow (CBF) provides critical blood supply to the myocardium so that it can appropriately meet the metabolic demands of the body. Dogmatically, there exist several known regulators and modulators of CBF that include local metabolites and neurohormonal factors that can influence the function of the coronary circulation. In disease states such as diabetes and myocardial ischemia, these regulators are impaired or shifted such that CBF is reduced. Although functional considerations have been and continued to be well studied, more recent evidence builds upon established studies that collectively suggest that the relative roles of coronary structure, biomechanics, and the influence of cardiac biomechanics via extravascular compression may also play a significant role in dictating CBF. In this mini review, we discuss these regulators of CBF under normal and pathophysiological conditions and their potential influence on the control of CBF.
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Affiliation(s)
- Patricia E McCallinhart
- Center for Cardiovascular Research, The Heart Center, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, Ohio
| | - Benjamin W Scandling
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio.,Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Aaron J Trask
- Center for Cardiovascular Research, The Heart Center, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, Ohio.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio
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Razavi A, Sachdeva S, Frommelt PC, LaDisa JF. Patient-Specific Numerical Analysis of Coronary Flow in Children With Intramural Anomalous Aortic Origin of Coronary Arteries. Semin Thorac Cardiovasc Surg 2020; 33:155-167. [PMID: 32858220 DOI: 10.1053/j.semtcvs.2020.08.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 08/21/2020] [Indexed: 11/11/2022]
Abstract
Unroofing surgery for anomalous aortic origin of a coronary artery (AAOCA) alters coronary anatomy by opening the intramural segment so that the anomalous coronary orifice arises perpendicularly from appropriate aortic sinus. Computational fluid dynamics modeling (CFD) allows for quantification of hemodynamics linked to morbidity such as wall shear stress (WSS), relative to patient-specific features like the angle of origin (AO). We hypothesize that CFD will reveal abnormal WSS indices in unroofed arteries that are related to AO. Six AAOCA patients (3 left, 3 right) status post unroofing (median = 13.5 years, range 9-17) underwent cardiac magnetic resonance imaging. CFD models were created from pre (n = 2) and postunroofing (n = 6) cardiac magnetic resonance imaging data, for the anomalous and contralateral normally-arising arteries. Downstream vasculature was represented by lumped parameter networks. Time-averaged WSS (TAWSS) and oscillatory shear index (OSI) were quantified relative to AO and measured hemodynamics. TAWSS was elevated along the outer wall of the normally-arising left vs right coronary arteries, as well as along unroofed left vs right coronary arteries (n = 6/group). No significant differences were noted when comparing unroofed and same-sided normally-arising coronaries. TAWSS was reduced after unroofing (eg, 276 ± 28 dyne/cm2 vs 91 ± 15 dyne/cm2; n = 2/group). Models with more acute preoperative AO indicated lower TAWSS at the proximity of ostium. Differences in OSI were not significant. Different flow patterns exist natively between right and left coronary arteries. Unroofing may normalize TAWSS but with variance related to the AO. This study suggests CFD may help stratify risk in AAOCA.
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Affiliation(s)
- Atefeh Razavi
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin.
| | | | - Peter C Frommelt
- Children's Hospital of Wisconsin, Milwaukee, Wisconsin; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - John F LaDisa
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin; Departments of Cardiovascular Medicine and Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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10
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Magder S. Diastolic pressure should be used to guide management of patients in shock: PRO. J Crit Care 2020; 51:241-243. [PMID: 31126439 DOI: 10.1016/j.jcrc.2018.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/30/2018] [Accepted: 09/04/2018] [Indexed: 01/08/2023]
Abstract
Based primarily on the rational that adequate diastolic pressure is needed to maintain sufficient coronary blood for myocardial needs, diastolic pressure has been proposed as a treatment target for patients in shock. To date, clinical evidence supporting this is limited to observational data. Key points are that what is important for tissues is flow not pressure; the coronary circulation has very large flow reserves and can maintain flow with a low pressure; raising arterial pressure by only increasing vascular resistance does not alter tissue perfusion and could even increase myocardial oxygen demand. Targeting diastolic pressure can lead to over use of vasopressors, which studies have associated with worse outcome. Pressor management in shock should include assessment of indicators of tissue perfusion and changes in flow if possible.
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Affiliation(s)
- Sheldon Magder
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, Quebec H4A 3J1, Canada..
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11
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Hughes AD, Parker KH. The modified arterial reservoir: An update with consideration of asymptotic pressure ( P∞) and zero-flow pressure ( Pzf). Proc Inst Mech Eng H 2020; 234:1288-1299. [PMID: 32367773 PMCID: PMC7705641 DOI: 10.1177/0954411920917557] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This article describes the modified arterial reservoir in detail. The modified arterial reservoir makes explicit the wave nature of both reservoir (Pres) and excess pressure (Pxs). The mathematical derivation and methods for estimating Pres in the absence of flow velocity data are described. There is also discussion of zero-flow pressure (Pzf), the pressure at which flow through the circulation ceases; its relationship to asymptotic pressure (P∞) estimated by the reservoir model; and the physiological interpretation of Pzf . A systematic review and meta-analysis provides evidence that Pzf differs from mean circulatory filling pressure.
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Affiliation(s)
- Alun D Hughes
- MRC Unit for Lifelong Health and Ageing at UCL, Department of Population Science and Experimental Medicine, Institute of Cardiovascular Science, University College London, London, UK
| | - Kim H Parker
- Department of Bioengineering, Imperial College London, London, UK
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12
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Gewirtz H. Coronary circulation: Pressure/flow parameters for assessment of ischemic heart disease. J Nucl Cardiol 2019; 26:459-470. [PMID: 29637523 DOI: 10.1007/s12350-018-1270-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 03/23/2018] [Indexed: 01/10/2023]
Abstract
Both invasive and non-invasive parameters have been reported for assessment of the physiological status of the coronary circulation. Fractional flow reserve and coronary (or myocardial) flow reserve may be obtained by invasive or non-invasive means. These metrics of coronary stenosis severity have achieved wide clinical acceptance for guiding revascularization decisions and risk stratification. Other indices are obtained invasively (e.g., instantaneous wave-free ratio, iFR; hyperemic stenosis resistance) or non-invasively (e.g., PET absolute myocardial blood flow (mL/min/g)) and have been used for the same purposes. Both iFR, and whole-cycle distal coronary to aortic mean pressure (Pd/Pa) are measured under basal condition and used for assessment of hemodynamic stenosis severity as is index of basal stenosis resistance (BSR). These metrics typically are dichotomized at an empirically derived cut point into "normal" and "abnormal" categories for purposes of clinical decision making and data analysis. Once dichotomized the indices do not always point in the same direction and so confusion may arise. This review, therefore, will present basic principles relevant to understanding commonly employed metrics of the physiological status of the coronary circulation, potential strengths and weaknesses, and hopefully an improved appreciation of the clinical information provided by each.
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Affiliation(s)
- Henry Gewirtz
- Department of Medicine (Cardiology Division), Harvard Medical School, Massachusetts General Hospital, Boston, MA, 02114, USA.
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13
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Mohy-Ud-Din H, Boutagy NE, Stendahl JC, Zhuang ZW, Sinusas AJ, Liu C. Quantification of intramyocardial blood volume with 99mTc-RBC SPECT-CT imaging: A preclinical study. J Nucl Cardiol 2018; 25:2096-2111. [PMID: 28695406 PMCID: PMC5985225 DOI: 10.1007/s12350-017-0970-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 06/13/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Currently, there is no established non-invasive imaging approach to directly evaluate myocardial microcirculatory function in order to diagnose microvascular disease independent of co-existing epicardial disease. In this work, we developed a methodological framework for quantification of intramyocardial blood volume (IMBV) as a novel index of microcirculatory function with SPECT/CT imaging of 99mTc-labeled red blood cells (RBCs). METHODS Dual-gated myocardial SPECT/CT equilibrium imaging of 99mTc-RBCs was performed on twelve canines under resting conditions. Five correction schemes were studied: cardiac gating with no other corrections (CG), CG with attenuation correction (CG + AC), CG + AC with scatter correction (CG + AC + SC), dual cardiorespiratory gating with AC + SC (DG + AC + SC), and DG + AC + SC with partial volume correction (DG + AC + SC + PVC). Quantification of IMBV using each approach was evaluated in comparison to those obtained from all corrections. The in vivo SPECT estimates of IMBV values were validated against those obtained from ex vivo microCT imaging of the casted hearts. RESULTS The estimated IMBV with all corrections was 0.15 ± 0.03 for the end-diastolic phase and 0.11 ± 0.03 for the end-systolic phase. The cycle-dependent change in IMBV (ΔIMBV) with all corrections was 23.9 ± 8.6%. Schemes that applied no correction or partial correction resulted in significant over-estimation of IMBV and significant under-underestimation of ΔIMBV. Estimates of IMBV and ΔIMBV using all corrections were consistent with values reported in the literature using invasive techniques. In vivo SPECT estimates of IMBV strongly correlated (R2 ≥ 0.70) with ex vivo measures for the various correction schemes, while the fully corrected scheme yielded the smallest bias. CONCLUSIONS Non-invasive quantification of IMBV is feasible using 99mTc-RBCs SPECT/CT imaging, however, requires full compensation of physical degradation factors.
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Affiliation(s)
- Hassan Mohy-Ud-Din
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA.
- Shaukat Khanum Memorial Cancer Hospital and Research Center, 7-A, Block R-3, Johar Town, Lahore, 54000, Pakistan.
| | - Nabil E Boutagy
- Section of Cardiovascular Medicine, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - John C Stendahl
- Section of Cardiovascular Medicine, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Zhen W Zhuang
- Section of Cardiovascular Medicine, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Albert J Sinusas
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
- Section of Cardiovascular Medicine, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Chi Liu
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA.
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14
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Ge X, Yin Z, Fan Y, Vassilevski Y, Liang F. A multi-scale model of the coronary circulation applied to investigate transmural myocardial flow. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3123. [PMID: 29947132 DOI: 10.1002/cnm.3123] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/03/2018] [Accepted: 06/17/2018] [Indexed: 06/08/2023]
Abstract
Distribution of blood flow in myocardium is a key determinant of the localization and severity of myocardial ischemia under impaired coronary perfusion conditions. Previous studies have extensively demonstrated the transmural difference of ischemic vulnerability. However, it remains incompletely understood how transmural myocardial flow is regulated under in vivo conditions. In the present study, a computational model of the coronary circulation was developed to quantitatively evaluate the sensitivity of transmural flow distribution to various cardiovascular and hemodynamic factors. The model was further incorporated with the flow autoregulatory mechanism to simulate the regulation of myocardial flow in the presence of coronary artery stenosis. Numerical tests demonstrated that heart rate (HR), intramyocardial tissue pressure (Pim ), and coronary perfusion pressure (Pper ) were the major determinant factors for transmural flow distribution (evaluated by the subendocardial-to-subepicardial (endo/epi) flow ratio) and that the flow autoregulatory mechanism played an important compensatory role in preserving subendocardial perfusion against reduced Pper . Further analysis for HR variation-induced hemodynamic changes revealed that the rise in endo/epi flow ratio accompanying HR decrease was attributable not only to the prolongation of cardiac diastole relative to systole, but more predominantly to the fall in Pim . Moreover, it was found that Pim and Pper interfered with each other with respect to their influence on transmural flow distribution. These results demonstrate the interactive effects of various cardiovascular and hemodynamic factors on transmural myocardial flow, highlighting the importance of taking into account patient-specific conditions in the explanation of clinical observations.
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Affiliation(s)
- Xinyang Ge
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhaofang Yin
- Department of Cardiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Yuqi Fan
- Department of Cardiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Yuri Vassilevski
- Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, 119333, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700, Russia
- Sechenov University, Moscow, 119991, Russia
| | - Fuyou Liang
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai Jiao Tong University, Shanghai, 200240, China
- Sechenov University, Moscow, 119991, Russia
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15
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Kiel AM, Goodwill AG, Baker HE, Dick GM, Tune JD. Local metabolic hypothesis is not sufficient to explain coronary autoregulatory behavior. Basic Res Cardiol 2018; 113:33. [PMID: 30073416 DOI: 10.1007/s00395-018-0691-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 06/19/2018] [Accepted: 07/04/2018] [Indexed: 01/21/2023]
Abstract
The local metabolic hypothesis proposes that myocardial oxygen tension determines the degree of autoregulation by increasing the production of vasodilator metabolites as perfusion pressure is reduced. Thus, normal physiologic levels of coronary venous PO2, an index of myocardial oxygenation, are proposed to be required for effective autoregulation. The present study challenged this hypothesis through determination of coronary responses to changes in coronary perfusion pressure (CPP 140-40 mmHg) in open-chest swine in the absence (n = 7) and presence of euvolemic hemodilution (~ 50% reduction in hematocrit), with (n = 5) and without (n = 6) infusion of dobutamine to augment MVO2. Coronary venous PO2 decreased over similar ranges (~ 28-15 mmHg) as CPP was lowered from 140 to 40 mmHg in each of the groups. However, coronary venous PO2 was not associated with changes in coronary blood flow (r = - 0.11; P = 0.29) or autoregulatory gain (r = - 0.29; P = 0.12). Coronary zero-flow pressure (Pzf) was measured in 20 mmHg increments and determined to be directly related to vascular resistance (r = 0.71; P < 0.001). Further analysis demonstrated that changes in coronary blood flow remained minimal at Pzf > 20 mmHg, but progressively increased as Pzf decreased below this threshold value (r = 0.68; P < 0.001). Coronary Pzf was also positively correlated with autoregulatory gain (r = 0.43; P = 0.001). These findings support that coronary autoregulatory behavior is predominantly dependent on an adequate degree of underlying vasomotor tone, independent of normal myocardial oxygen tension.
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Affiliation(s)
- Alexander M Kiel
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA.,Weldon School of Biomedical Engineering, Purdue University, 206 S Martin Jischke Dr, West Lafayette, IN, 47907, USA
| | - Adam G Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Hana E Baker
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Gregory M Dick
- California Medical Innovations Institute, 11107 Roselle Street, San Diego, CA, 92121, USA
| | - Johnathan D Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA.
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16
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Mynard JP, Penny DJ, Smolich JJ. Major influence of a 'smoke and mirrors' effect caused by wave reflection on early diastolic coronary arterial wave intensity. J Physiol 2018; 596:993-1017. [PMID: 29318640 DOI: 10.1113/jp274710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/02/2018] [Indexed: 01/25/2023] Open
Abstract
KEY POINTS Coronary wave intensity analysis (WIA) is an emerging technique for assessing upstream and downstream influences on myocardial perfusion. It is thought that a dominant backward decompression wave (BDWdia ) is generated by a distal suction effect, while early-diastolic forward decompression (FDWdia ) and compression (FCWdia ) waves originate in the aorta. We show that wave reflection also makes a substantial contribution to FDWdia , FCWdia and BDWdia , as quantified by a novel method. In 18 sheep, wave reflection accounted for ∼70% of BDWdia , whereas distal suction dominated in a computer model representing a hypertensive human. Non-linear addition/subtraction of mechanistically distinct waves (e.g. wave reflection and distal suction) obfuscates the true contribution of upstream and downstream forces on measured waves (the 'smoke and mirrors' effect). The mechanisms underlying coronary WIA are more complex than previously thought and the impact of wave reflection should be considered when interpreting clinical and experimental data. ABSTRACT Coronary arterial wave intensity analysis (WIA) is thought to provide clear insight into upstream and downstream forces on coronary flow, with a large early-diastolic surge in coronary flow accompanied by a prominent backward decompression wave (BDWdia ), as well as a forward decompression wave (FDWdia ) and forward compression wave (FCWdia ). The BDWdia is believed to arise from distal suction due to release of extravascular compression by relaxing myocardium, while FDWdia and FCWdia are thought to be transmitted from the aorta into the coronary arteries. Based on an established multi-scale computational model and high-fidelity measurements from the proximal circumflex artery (Cx) of 18 anaesthetized sheep, we present evidence that wave reflection has a major impact on each of these three waves, with a non-linear addition/subtraction of reflected waves obscuring the true influence of upstream and downstream forces through concealment and exaggeration, i.e. a 'smoke and mirrors' effect. We also describe methods, requiring additional measurement of aortic WIA, for unravelling the separate influences of wave reflection versus active upstream/downstream forces on coronary waves. Distal wave reflection accounted for ∼70% of the BDWdia in sheep, but had a lesser influence (∼25%) in the computer model representing a hypertensive human. Negative reflection of the BDWdia at the coronary-aortic junction attenuated the Cx FDWdia (by ∼40% in sheep) and augmented Cx FCWdia (∼5-fold), relative to the corresponding aortic waves. We conclude that wave reflection has a major influence on early-diastolic WIA, and thus needs to be considered when interpreting coronary WIA profiles.
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Affiliation(s)
- Jonathan P Mynard
- Heart Research, Clinical Sciences, Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia.,Department of Cardiology, Royal Children's Hospital, Parkville, VIC 3052, Australia
| | - Daniel J Penny
- Heart Research, Clinical Sciences, Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia.,Department of Cardiology, Royal Children's Hospital, Parkville, VIC 3052, Australia.,Institute of Reproduction and Development, Monash University, Clayton, VIC, Australia
| | - Joseph J Smolich
- Heart Research, Clinical Sciences, Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia.,Institute of Reproduction and Development, Monash University, Clayton, VIC, Australia
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17
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Boileau E, Pant S, Roobottom C, Sazonov I, Deng J, Xie X, Nithiarasu P. Estimating the accuracy of a reduced-order model for the calculation of fractional flow reserve (FFR). INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34. [PMID: 28600860 DOI: 10.1002/cnm.2908] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/06/2017] [Accepted: 06/06/2017] [Indexed: 06/07/2023]
Abstract
Image-based noninvasive fractional flow reserve (FFR) is an emergent approach to determine the functional relevance of coronary stenoses. The present work aimed to determine the feasibility of using a method based on coronary computed tomography angiography (CCTA) and reduced-order models (0D-1D) for the evaluation of coronary stenoses. The reduced-order methodology (cFFRRO ) was kept as simple as possible and did not include pressure drop or stenosis models. The geometry definition was incorporated into the physical model used to solve coronary flow and pressure. cFFRRO was assessed on a virtual cohort of 30 coronary artery stenoses in 25 vessels and compared with a standard approach based on 3D computational fluid dynamics (cFFR3D ). In this proof-of-concept study, we sought to investigate the influence of geometry and boundary conditions on the agreement between both methods. Performance on a per-vessel level showed a good correlation between both methods (Pearson's product-moment R=0.885, P<0.01), when using cFFR3D as the reference standard. The 95% limits of agreement were -0.116 and 0.08, and the mean bias was -0.018 (SD =0.05). Our results suggest no appreciable difference between cFFRRO and cFFR3D with respect to lesion length and/or aspect ratio. At a fixed aspect ratio, however, stenosis severity and shape appeared to be the most critical factors accounting for differences in both methods. Despite the assumptions inherent to the 1D formulation, asymmetry did not seem to affect the agreement. The choice of boundary conditions is critical in obtaining a functionally significant drop in pressure. Our initial data suggest that this approach may be part of a broader risk assessment strategy aimed at increasing the diagnostic yield of cardiac catheterisation for in-hospital evaluation of haemodynamically significant stenoses.
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Affiliation(s)
- Etienne Boileau
- Zienkiewicz Centre for Computational Engineering, Engineering Central, College of Engineering, Swansea University Bay Campus, Swansea, SA1 8EN, UK
| | - Sanjay Pant
- Zienkiewicz Centre for Computational Engineering, Engineering Central, College of Engineering, Swansea University Bay Campus, Swansea, SA1 8EN, UK
| | - Carl Roobottom
- Derriford Hospital and Peninsula Medical School, Plymouth Hospitals NHS Trust, Derriford Rd, Crownhill, Plymouth, PL6 8DH,, UK
| | - Igor Sazonov
- Zienkiewicz Centre for Computational Engineering, Engineering Central, College of Engineering, Swansea University Bay Campus, Swansea, SA1 8EN, UK
| | - Jingjing Deng
- Department of Computer Science, Swansea University, Swansea, SA2 8PP, UK
| | - Xianghua Xie
- Department of Computer Science, Swansea University, Swansea, SA2 8PP, UK
| | - Perumal Nithiarasu
- Zienkiewicz Centre for Computational Engineering, Engineering Central, College of Engineering, Swansea University Bay Campus, Swansea, SA1 8EN, UK
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18
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Gewirtz H. PET measurements of myocardial blood flow post myocardial infarction: Relationship to invasive and cardiac magnetic resonance studies and potential clinical applications. J Nucl Cardiol 2017; 24:1883-1892. [PMID: 28577226 DOI: 10.1007/s12350-017-0930-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 05/17/2017] [Indexed: 01/10/2023]
Abstract
This review focuses on clinical studies concerning assessment of coronary microvascular and conduit vessel function primarily in the context of acute and sub acute myocardial infarction (MI). The ability of quantitative PET measurements of myocardial blood flow (MBF) to delineate underlying pathophysiology and assist in clinical decision making in this setting is discussed. Likewise, considered are physiological metrics fractional flow reserve, coronary flow reserve, index of microvascular resistance (FFR, CFR, IMR) obtained from invasive studies performed in the cardiac catheterization laboratory, typically at the time of PCI for MI. The role both of invasive studies and cardiac magnetic resonance (CMR) imaging in assessing microvascular function, a key determinant of prognosis, is reviewed. The interface between quantitative PET MBF measurements and underlying pathophysiology, as demonstrated both by invasive and CMR methodology, is discussed in the context of optimal interpretation of the quantitative PET MBF exam and its potential clinical applications.
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Affiliation(s)
- Henry Gewirtz
- Department of Medicine, Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Yawkey 5E, 55 Fruit St, Boston, MA, 02114, USA.
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19
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Soares JS, Li DS, Lai E, Gorman JH, Gorman RC, Sacks MS. Modeling of Myocardium Compressibility and its Impact in Computational Simulations of the Healthy and Infarcted Heart. FUNCTIONAL IMAGING AND MODELING OF THE HEART : ... INTERNATIONAL WORKSHOP, FIMH ..., PROCEEDINGS. FIMH 2017; 10263:493-501. [PMID: 31080965 PMCID: PMC6510496 DOI: 10.1007/978-3-319-59448-4_47] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Simulation of heart function requires many components, including accurate descriptions of regional mechanical behavior of the normal and infarcted myocardium. Myocardial compressibility has been known for at least two decades, however its experimental measurement and incorporation into compu-tational simulations has not yet been widely utilized in contemporary cardiac models. In the present work, based on novel in-vivo ovine experimental data, we developed a specialized compressible model that reproduces the peculiar unim-odal compressible behavior of myocardium. Such simulations will be extremely valuable to understand etiology and pathophysiology of myocardium remodeling and its impact on tissue-level properties and organ-level cardiac function.
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Affiliation(s)
- Joao S Soares
- Center for Computational Simulation, Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
| | - David S Li
- Center for Computational Simulation, Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
| | - Eric Lai
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- Center for Computational Simulation, Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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20
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Commentary on: CMR study of systolic myocardial volume gain in the dilated, hypertrophied, and normal heart. Clin Radiol 2017; 72:293-294. [DOI: 10.1016/j.crad.2017.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 01/03/2017] [Indexed: 11/17/2022]
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21
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Echavarria-Pinto M, Petraco R, van de Hoef TP, Gonzalo N, Nijjer S, Tarkin JM, Ibanez B, Sen S, Jimenez-Quevedo P, Nunez-Gil IJ, Nombela-Franco L, Alfonso F, Fernandez-Ortiz A, Macaya C, Piek JJ, Davies J, Escaned J. Fractional flow reserve and minimum Pd/Pa ratio during intravenous adenosine infusion: very similar but not always the same. EUROINTERVENTION 2017; 11:1013-9. [PMID: 25366652 DOI: 10.4244/eijy14m10_09] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
AIMS Maximum and stable hyperaemia are critical prerequisites for the accurate measurement of fractional flow reserve (FFR). However, in some patients in whom hyperaemia is induced through a central vein (IV) the minimum distal coronary pressure to aortic pressure ratio (Pd/Pa ratio) develops before the stabilisation of hyperaemia. We sought to describe the prevalence, magnitude and clinical implications of this phenomenon. METHODS AND RESULTS The FFR tracing archive of a single institution was reviewed and a total of 104 high-quality IV-FFR recordings from 90 patients were identified. Whenever the minimum Pd/Pa ratio was found before the onset of stable hyperaemia, a search for the lowest Pd/Pa ratio within the steady-state hyperaemic plateau was performed and labelled as FFRstable. Whilst in most cases the minimum Pd/Pa ratio developed during stable hyperaemia, in 19 cases (prevalence of 18.3% [95% CI: 12.0% to 26.8%]) this value was found before the stabilisation of the hyperaemic state. In such cases, the minimum Pd/Pa ratio stabilised later at a higher level (0.77±0.09 vs. 0.81±0.08, p<0.001) (mean difference, 0.03±0.02, range, 0.01 to 0.10). In terms of dichotomous classification of stenosis severity and if FFRstable had been used to decide on revascularisation, reclassification would have occurred in three (2.9%) cases, all presenting a minimum Pd/Pa ratio ≤0.80 with FFRstable >0.80. CONCLUSIONS During IV adenosine infusion, the minimum Pd/Pa ratio occurs before the stabilisation of hyperaemia in a significant proportion of cases. While the overall difference between the minimum Pd/Pa ratio and its FFRstable counterpart is small, reclassification of stenosis severity might occur, if choosing between the minimum and stable values of FFR within the same trace.
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Affiliation(s)
- Mauro Echavarria-Pinto
- Hospital Clinico San Carlos and Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
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22
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Lu X, Kassab GS. Integrins mediate mechanical compression-induced endothelium-dependent vasodilation through endothelial nitric oxide pathway. ACTA ACUST UNITED AC 2016; 146:221-32. [PMID: 26324675 PMCID: PMC4555471 DOI: 10.1085/jgp.201411350] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Integrins mediate endothelial NO production and vasodilation in response to the compression of muscle arterioles. Cardiac and skeletal muscle contraction lead to compression of intramuscular arterioles, which, in turn, leads to their vasodilation (a process that may enhance blood flow during muscle activity). Although endothelium-derived nitric oxide (NO) has been implicated in compression-induced vasodilation, the mechanism whereby arterial compression elicits NO production is unclear. We cannulated isolated swine (n = 39) myocardial (n = 69) and skeletal muscle (n = 60) arteriole segments and exposed them to cyclic transmural pressure generated by either intraluminal or extraluminal pressure pulses to simulate compression in contracting muscle. We found that the vasodilation elicited by internal or external pressure pulses was equivalent; moreover, vasodilation in response to pressure depended on changes in arteriole diameter. Agonist-induced endothelium-dependent and -independent vasodilation was used to verify endothelial and vascular smooth muscle cell viability. Vasodilation in response to cyclic changes in transmural pressure was smaller than that elicited by pharmacological activation of the NO signaling pathway. It was attenuated by inhibition of NO synthase and by mechanical removal of the endothelium. Stemming from previous observations that endothelial integrin is implicated in vasodilation in response to shear stress, we found that function-blocking integrin α5β1 or αvβ3 antibodies attenuated cyclic compression–induced vasodilation and NOx (NO−2 and NO−3) production, as did an RGD peptide that competitively inhibits ligand binding to some integrins. We therefore conclude that integrin plays a role in cyclic compression–induced endothelial NO production and thereby in the vasodilation of small arteries during cyclic transmural pressure loading.
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Affiliation(s)
- Xiao Lu
- Department of Biomedical Engineering, Department of Cellular and Integrative Physiology, Department of Surgery, and Indiana Center for Vascular Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
| | - Ghassan S Kassab
- Department of Biomedical Engineering, Department of Cellular and Integrative Physiology, Department of Surgery, and Indiana Center for Vascular Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 Department of Biomedical Engineering, Department of Cellular and Integrative Physiology, Department of Surgery, and Indiana Center for Vascular Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 Department of Biomedical Engineering, Department of Cellular and Integrative Physiology, Department of Surgery, and Indiana Center for Vascular Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 Department of Biomedical Engineering, Department of Cellular and Integrative Physiology, Department of Surgery, and Indiana Center for Vascular Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
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23
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Arthurs CJ, Lau KD, Asrress KN, Redwood SR, Figueroa CA. A mathematical model of coronary blood flow control: simulation of patient-specific three-dimensional hemodynamics during exercise. Am J Physiol Heart Circ Physiol 2016; 310:H1242-58. [PMID: 26945076 PMCID: PMC4867386 DOI: 10.1152/ajpheart.00517.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 03/01/2016] [Indexed: 01/07/2023]
Abstract
This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit.
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Affiliation(s)
- Christopher J Arthurs
- Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, United Kingdom;
| | - Kevin D Lau
- Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, United Kingdom; Departments of Surgery and Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Kaleab N Asrress
- King's College London British Heart Foundation Centre of Excellence, The Rayne Institute, St. Thomas' Hospital Campus, London, United Kingdom; and
| | - Simon R Redwood
- King's College London British Heart Foundation Centre of Excellence, The Rayne Institute, St. Thomas' Hospital Campus, London, United Kingdom; and
| | - C Alberto Figueroa
- Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, United Kingdom; Departments of Surgery and Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
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24
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Lee J, Nordsletten D, Cookson A, Rivolo S, Smith N. In silico coronary wave intensity analysis: application of an integrated one-dimensional and poromechanical model of cardiac perfusion. Biomech Model Mechanobiol 2016; 15:1535-1555. [PMID: 27008197 PMCID: PMC5106513 DOI: 10.1007/s10237-016-0782-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 03/08/2016] [Indexed: 01/09/2023]
Abstract
Coronary wave intensity analysis (cWIA) is a diagnostic technique based on invasive measurement of coronary pressure and velocity waveforms. The theory of WIA allows the forward- and backward-propagating coronary waves to be separated and attributed to their origin and timing, thus serving as a sensitive and specific cardiac functional indicator. In recent years, an increasing number of clinical studies have begun to establish associations between changes in specific waves and various diseases of myocardium and perfusion. These studies are, however, currently confined to a trial-and-error approach and are subject to technological limitations which may confound accurate interpretations. In this work, we have developed a biophysically based cardiac perfusion model which incorporates full ventricular–aortic–coronary coupling. This was achieved by integrating our previous work on one-dimensional modelling of vascular flow and poroelastic perfusion within an active myocardial mechanics framework. Extensive parameterisation was performed, yielding a close agreement with physiological levels of global coronary and myocardial function as well as experimentally observed cumulative wave intensity magnitudes. Results indicate a strong dependence of the backward suction wave on QRS duration and vascular resistance, the forward pushing wave on the rate of myocyte tension development, and the late forward pushing wave on the aortic valve dynamics. These findings are not only consistent with experimental observations, but offer a greater specificity to the wave-originating mechanisms, thus demonstrating the value of the integrated model as a tool for clinical investigation.
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Affiliation(s)
- Jack Lee
- Department of Biomedical Engineering, King's College London, 3rd Floor, Lambeth Wing, St Thomas' Hospital, London, UK.
| | - David Nordsletten
- Department of Biomedical Engineering, King's College London, 3rd Floor, Lambeth Wing, St Thomas' Hospital, London, UK
| | - Andrew Cookson
- Department of Biomedical Engineering, King's College London, 3rd Floor, Lambeth Wing, St Thomas' Hospital, London, UK
| | - Simone Rivolo
- Department of Biomedical Engineering, King's College London, 3rd Floor, Lambeth Wing, St Thomas' Hospital, London, UK
| | - Nicolas Smith
- Department of Biomedical Engineering, King's College London, 3rd Floor, Lambeth Wing, St Thomas' Hospital, London, UK
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Wijntjens GWM, van Lavieren MA, van de Hoef TP, Piek JJ. Physiological assessment of coronary stenosis: a view from the coronary microcirculation. Interv Cardiol 2015. [DOI: 10.2217/ica.15.24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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26
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One-Dimensional Modelling of the Coronary Circulation. Application to Noninvasive Quantification of Fractional Flow Reserve (FFR). ACTA ACUST UNITED AC 2015. [DOI: 10.1007/978-3-319-15799-3_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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27
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Nolte F, van de Hoef TP, de Klerk W, Baan J, Lockie TP, Spaan JA, Piek JJ, Siebes M. Functional coronary stenosis severity assessed from the mean pressure gradient-velocity relationship obtained by contrast medium-induced submaximal hyperaemia. EUROINTERVENTION 2014; 10:320-8. [DOI: 10.4244/eijv10i3a55] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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28
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van Slochteren FJ, van der Spoel TIG, Hansen HHG, Bovendeerd PHM, Doevendans PA, Sluijter JPG, Chamuleau SAJ, de Korte CL. Layer-specific radiofrequency ultrasound-based strain analysis in a porcine model of ischemic cardiomyopathy validated by a geometric model. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:378-388. [PMID: 24315396 DOI: 10.1016/j.ultrasmedbio.2013.09.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 09/05/2013] [Accepted: 09/26/2013] [Indexed: 06/02/2023]
Abstract
Local layer-specific myocardial deformation after myocardial infarction (MI) has not been studied extensively although the sub-endocardium is more vulnerable to ischemia and interstitial fibrosis deposition. Radiofrequency (RF) ultrasound-based analysis could provide superior layer-specific radial strain estimation compared with clinically available deformation imaging techniques. In this study, we used RF-based myocardial deformation measurements to investigate layer-specific differences between healthy and damaged myocardium in a porcine model of chronic MI. RF data were acquired epicardially in healthy (n = 21) and infarcted (n = 5) regions of a porcine chronic MI model 12 wk post-MI. Radial and longitudinal strains were estimated in the sub-endocardial, mid-wall and sub-epicardial layers of the left ventricle. Collagen content was quantified in three layers of healthy and infarcted regions in five pigs. An analytical geometric model of the left ventricle was used to theoretically underpin the radial deformation estimated in different myocardial layers. Means ± standard errors of the peak radial and longitudinal strain estimates of the sub-endocardial, mid-wall and sub-epicardial layers of the healthy and infarcted tissue were: 82.7 ± 5.2% versus 39.9 ± 10.8% (p = 0.002), 63.6 ± 3.3% versus 38.8 ± 7.7% (p = 0.004) and 34.3 ± 3.0% versus 35.1 ± 5.2% (p = 0.9), respectively. The radial strain gradient between the sub-endocardium and the sub-epicardium had decreased 12 wk after MI, and histologic examination revealed the greatest increases in collagen in the sub-endocardial and mid-wall layers. Comparable normal peak radial strain values were found by geometric modeling when input values were derived from the in vivo measurements and literature. In conclusion, the estimated strain values are realistic and indicate that sub-endocardial radial strain in healthy tissue can amount to 80%. This high value can be explained by the cardiac geometry, as was illustrated by geometric modeling. After MI, strain values were decreased and collagen content was increased in the sub-endocardial and mid-wall layers. Layer-specific peak radial strain can be assessed by RF strain estimation and clearly differs between healthy and infarcted tissue. Although the relationship between tissue stiffness and tissue strain is not strictly local, this novel technique provides a valuable way to assess layer-specific regional cardiac function in a variety of myocardial diseases.
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Affiliation(s)
| | | | - Hendrik H G Hansen
- Medical Ultrasound Imaging Center, Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Peter H M Bovendeerd
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Pieter A Doevendans
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Joost P G Sluijter
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Steven A J Chamuleau
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
| | - Chris L de Korte
- Medical Ultrasound Imaging Center, Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Mynard JP, Penny DJ, Smolich JJ. Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation. Am J Physiol Heart Circ Physiol 2013; 306:H517-28. [PMID: 24363304 DOI: 10.1152/ajpheart.00603.2013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Multiscale modeling is a promising tool for the study of coronary hemodynamics. A key strength of this approach is that it accounts for microvascular properties and extravascular forces that differ regionally and transmurally, as well as wave propagation effects in the conduit arteries. However, little validation of such models has been reported and no models of the newborn coronary circulation have been described. We therefore validated a multiscale model of the left coronary circulation using high-fidelity data from nine adult sheep and nine newborn lambs and investigated whether wave propagation effects are more prominent in adults, whose body size (and hence wave transit distance) is greater. The model consisted of a one-dimensional (1D) network of the major conduit arteries and a lumped parameter model of microvascular beds. Intramyocardial pressure was considered to arise via contraction-related myocyte thickening and transmission of ventricular cavity pressure into the heart wall. 1D network geometry from published human anatomical data was scaled using myocardial weights, while subject-specific aortic pressure/flow and ventricular pressure formed model inputs. Total vascular resistance was determined iteratively from measured mean circumflex coronary flow (CxQ), but no fitting of phasic aspects of the waveform was performed. Excellent agreement was obtained between simulated and measured CxQ waveforms in most cases. Detailed flow waveform analysis did not clearly reveal a greater prominence of wave propagation effects in adults compared with newborns. This multiscale model is likely to be useful for investigating wave phenomena and phasic aspects of coronary flow in adults and during development.
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Affiliation(s)
- Jonathan P Mynard
- Heart Research Group, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
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Laughlin MH, Davis MJ, Secher NH, van Lieshout JJ, Arce-Esquivel AA, Simmons GH, Bender SB, Padilla J, Bache RJ, Merkus D, Duncker DJ. Peripheral circulation. Compr Physiol 2013; 2:321-447. [PMID: 23728977 DOI: 10.1002/cphy.c100048] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Blood flow (BF) increases with increasing exercise intensity in skeletal, respiratory, and cardiac muscle. In humans during maximal exercise intensities, 85% to 90% of total cardiac output is distributed to skeletal and cardiac muscle. During exercise BF increases modestly and heterogeneously to brain and decreases in gastrointestinal, reproductive, and renal tissues and shows little to no change in skin. If the duration of exercise is sufficient to increase body/core temperature, skin BF is also increased in humans. Because blood pressure changes little during exercise, changes in distribution of BF with incremental exercise result from changes in vascular conductance. These changes in distribution of BF throughout the body contribute to decreases in mixed venous oxygen content, serve to supply adequate oxygen to the active skeletal muscles, and support metabolism of other tissues while maintaining homeostasis. This review discusses the response of the peripheral circulation of humans to acute and chronic dynamic exercise and mechanisms responsible for these responses. This is accomplished in the context of leading the reader on a tour through the peripheral circulation during dynamic exercise. During this tour, we consider what is known about how each vascular bed controls BF during exercise and how these control mechanisms are modified by chronic physical activity/exercise training. The tour ends by comparing responses of the systemic circulation to those of the pulmonary circulation relative to the effects of exercise on the regional distribution of BF and mechanisms responsible for control of resistance/conductance in the systemic and pulmonary circulations.
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Affiliation(s)
- M Harold Laughlin
- Department of Medical Pharmacology and Physiology, and the Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA.
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van de Hoef TP, Meuwissen M, Escaned J, Davies JE, Siebes M, Spaan JAE, Piek JJ. Fractional flow reserve as a surrogate for inducible myocardial ischaemia. Nat Rev Cardiol 2013; 10:439-52. [DOI: 10.1038/nrcardio.2013.86] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Towards patient-specific modeling of coronary hemodynamics in healthy and diseased state. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:393792. [PMID: 23533537 PMCID: PMC3603622 DOI: 10.1155/2013/393792] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/25/2012] [Accepted: 01/03/2013] [Indexed: 01/09/2023]
Abstract
A model describing the primary relations between the cardiac muscle and coronary circulation might be useful for interpreting coronary hemodynamics in case multiple types of coronary circulatory disease are present. The main contribution of the present study is the coupling of a microstructure-based heart contraction model with a 1D wave propagation model. The 1D representation of the vessels enables patient-specific modeling of the arteries and/or can serve as boundary conditions for detailed 3D models, while the heart model enables the simulation of cardiac disease, with physiology-based parameter changes. Here, the different components of the model are explained and the ability of the model to describe coronary hemodynamics in health and disease is evaluated. Two disease types are modeled: coronary epicardial stenoses and left ventricular hypertrophy with an aortic valve stenosis. In all simulations (healthy and diseased), the dynamics of pressure and flow qualitatively agreed with observations described in literature. We conclude that the model adequately can predict coronary hemodynamics in both normal and diseased state based on patient-specific clinical data.
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van de Hoef TP, Nolte F, Rolandi MC, Piek JJ, van den Wijngaard JPHM, Spaan JAE, Siebes M. Coronary pressure-flow relations as basis for the understanding of coronary physiology. J Mol Cell Cardiol 2011; 52:786-93. [PMID: 21840314 DOI: 10.1016/j.yjmcc.2011.07.025] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 07/27/2011] [Accepted: 07/28/2011] [Indexed: 12/21/2022]
Abstract
Recent technological advancements in the area of intracoronary physiology, as well as non-invasive contrast perfusion imaging, allow to make clinical decisions with respect to percutaneous coronary interventions and to identify microcirculatory coronary pathophysiology. The basic characteristics of coronary hemodynamics, as described by pressure-flow relations in the normal and diseased heart, need to be understood for a proper interpretation of these physiological measurements. Especially the hyperemic coronary pressure-flow relation, as well as the influence of cardiac function on it, bears great clinical significance. The interaction of a coronary stenosis with the coronary pressure-flow relation can be understood from the stenosis pressure drop-flow velocity relationship. Based on these relationships the clinically applied concepts of coronary flow velocity reserve, fractional flow reserve, stenosis resistance and microvascular resistance are discussed. Attention is further paid to the heterogeneous nature of myocardial perfusion, the vulnerability of the subendocardium and the role of collateral flow on hyperemic coronary pressure-flow relations. This article is part of a Special Issue entitled "Coronary Blood Flow".
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Affiliation(s)
- Tim P van de Hoef
- Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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34
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Laughlin MH, Korthuis RJ, Duncker DJ, Bache RJ. Control of Blood Flow to Cardiac and Skeletal Muscle During Exercise. Compr Physiol 2011. [DOI: 10.1002/cphy.cp120116] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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35
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Kaimovitz B, Lanir Y, Kassab GS. A full 3-D reconstruction of the entire porcine coronary vasculature. Am J Physiol Heart Circ Physiol 2010; 299:H1064-76. [PMID: 20622105 PMCID: PMC2957345 DOI: 10.1152/ajpheart.00151.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 07/08/2010] [Indexed: 11/22/2022]
Abstract
We have previously reconstructed the entire coronary arterial tree of the porcine heart down to the first segment of capillaries. Here, we extend the vascular model through the capillary bed and the entire coronary venous system. The reconstruction was based on comprehensive morphometric data previously measured in the porcine heart. The reconstruction was formulated as a large-scale optimization process, subject to both global constraints relating to the location of the larger veins and to local constraints of measured morphological features. The venous network was partitioned into epicardial, transmural, and perfusion functional subnetworks. The epicardial portion was generated by a simulated annealing search for the optimal coverage of the area perfused by the arterial epicardial vessels. The epicardial subnetwork and coronary arterial capillary network served as boundary conditions for the reconstruction of the in-between transmural and perfusion networks, which were generated to optimize vascular homogeneity. Five sets of full coronary trees, which spanned the entire network down to the capillary level, were reconstructed. The total number of reconstructed venous segments was 17,148,946 ± 1,049,498 (n = 5), which spanned the coronary sinus (order -12) to the first segment of the venous capillary (order 0v). Combined with the reconstructed arterial network, the number of vessel segments for the entire coronary network added up to 27,307,376 ± 1,155,359 (n = 5). The reconstructed full coronary vascular network agreed with the gross anatomy of coronary networks in terms of structure, location of major vessels, and measured morphometric statistics of native coronary networks. This is the first full model of the entire coronary vasculature, which can serve as a foundation for realistic large-scale coronary flow analysis.
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Affiliation(s)
- Benjamin Kaimovitz
- Faculty of Biomedical Engineering, Israel Institute of Technology, Haifa, Israel
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36
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Diastolic dysfunction in diabetic patients assessed with Doppler echocardiography: relationship with coronary atherosclerotic burden and microcirculatory impairment. Rev Esp Cardiol 2010; 62:1395-403. [PMID: 20038406 DOI: 10.1016/s1885-5857(09)73534-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
INTRODUCTION AND OBJECTIVES Diabetes mellitus (DM) is associated with the development of both impaired left ventricular diastolic function (LVDF) and pathological changes in the coronary macro- and microcirculation. The aim of this study was to investigate the relationship between these manifestations of diabetic heart disease. METHODS The severity of atherosclerosis in the left anterior descending coronary artery (LAD) was quantified using intravascular ultrasound (IVUS) in 13 patients with DM and ischemic heart disease. The coronary flow velocity reserve (CFVR), instantaneous hyperemic diastolic velocity pressure slope index (IHDVPS) and zero-flow pressure were derived from digital intracoronary pressure and flow velocity measurements. The relationships between indices of LVDF (i.e. E/A and E/e' ratios) and intracoronary measurements were assessed. RESULTS The left ventricular ejection fraction was 66+/-7%, and the LVDF indices were: E/A=0.92+/-0.38 and E/e'=9.90+/-2.80. There was a direct proportional relationship (r=0.62; P=.02) between E/e' and coronary resistance (1.93+/-0.74 mmHg/s) and an inverse proportional relationship (r=-0.64; P=.02) between E/e' and IHDVPS (1.56+/-0.50 cm/s/mmHg). However, no significant relationship was found between either LVDF index and CFVR (2.43+/-0.56) or coronary zero-flow pressure (40.41+/-10.66 mmHg). The volume of atheroma in the proximal 20 mm of the LAD (179.34+/-57.48 .l, with an average plaque area of 8.39+/-2.20 mm2) was not related to either LVDF index. CONCLUSIONS In patients with DM and coronary atherosclerosis, there appeared to be a relationship between LVDF impairment (assessed by the E/e' ratio) and structural changes in the microcirculation.
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37
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Disfunción diastólica del paciente diabético estimada con ecocardiografía Doppler: relación con la ateromatosis y la disfunción microcirculatoria coronarias. Rev Esp Cardiol 2009. [DOI: 10.1016/s0300-8932(09)73125-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Huo Y, Kassab GS. Effect of compliance and hematocrit on wall shear stress in a model of the entire coronary arterial tree. J Appl Physiol (1985) 2009; 107:500-5. [PMID: 19541733 PMCID: PMC2724323 DOI: 10.1152/japplphysiol.91013.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Accepted: 06/12/2009] [Indexed: 11/22/2022] Open
Abstract
A hemodynamic analysis is implemented in the entire coronary arterial tree of diastolically arrested, vasodilated pig heart that takes into account vessel compliance and blood viscosity in each vessel of a large-scale simulation involving millions of vessels. The feed hematocrit (Hct) is varied at the inlet of the coronary arterial tree, and the Fahraeus-Lindqvist effect and phase separation are considered throughout the vasculature. The major findings are as follows: 1) vessel compliance is the major determinant of nonlinearity of the pressure-flow relation, and 2) changes in Hct influence wall shear stress (WSS) in epicardial coronary arteries more significantly than in transmural and perfusion arterioles because of the Fahraeus-Lindqvist effect. The present study predicts the flow rate as a second-order polynomial function of inlet pressure due to vessel compliance. WSS in epicardial coronary arteries increases >15% with an increase of feed Hct from 45% to 60% and decreases >15% with a decrease of feed Hct from 45% to 30%, whereas WSS in small arterioles is not affected as feed Hct changes in this range. These findings have important implications for acute Hct changes under vasodilated conditions.
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Affiliation(s)
- Yunlong Huo
- Department of Biomedical Engineering, Surgery, and Cellular and Integrative Physiology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
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Knaapen P, Camici PG, Marques KM, Nijveldt R, Bax JJ, Westerhof N, Götte MJW, Jerosch-Herold M, Schelbert HR, Lammertsma AA, van Rossum AC. Coronary microvascular resistance: methods for its quantification in humans. Basic Res Cardiol 2009; 104:485-98. [PMID: 19468781 PMCID: PMC2722717 DOI: 10.1007/s00395-009-0037-z] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 05/11/2009] [Accepted: 05/13/2009] [Indexed: 12/20/2022]
Abstract
Coronary microvascular dysfunction is a topic that has recently gained considerable interest in the medical community owing to the growing awareness that microvascular dysfunction occurs in a number of myocardial disease states and has important prognostic implications. With this growing awareness, comes the desire to accurately assess the functional capacity of the coronary microcirculation for diagnostic purposes as well as to monitor the effects of therapeutic interventions that are targeted at reversing the extent of coronary microvascular dysfunction. Measurements of coronary microvascular resistance play a pivotal role in achieving that goal and several invasive and noninvasive methods have been developed for its quantification. This review is intended to provide an update pertaining to the methodology of these different imaging techniques, including the discussion of their strengths and weaknesses.
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Affiliation(s)
- Paul Knaapen
- Department of Cardiology, VU University Medical Center, Amsterdam, The Netherlands.
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40
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Jacobs J, Algranati D, Lanir Y. Lumped flow modeling in dynamically loaded coronary vessels. J Biomech Eng 2009; 130:054504. [PMID: 19045528 DOI: 10.1115/1.2979877] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Most of the myriad (order of 10(9)) interconnected coronary vessels interact nonlinearly with their embedding contracting myocardium. Their dynamic flow can be simulated based on a nonlinear distributive segmental flow model involving highly nonlinear partial differential equations. Such network flow analysis, although of high accuracy, is computationally excessively complex. On the other hand, a corresponding nonlinear lumped analysis is significantly less demanding since it involves ordinary differential equations. This is, however, at the detriment of accuracy. In the present technical report, a nonlinear lumped representation of coronary segmental flow is presented and tested against predictions of the corresponding distributive analysis. The results suggest that under physiological conditions, the proposed lumped model achieves similar accuracy to the distributive one, yet with considerably higher computational speed.
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Affiliation(s)
- J Jacobs
- Faculty of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
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Abstract
Exercise is the most important physiological stimulus for increased myocardial oxygen demand. The requirement of exercising muscle for increased blood flow necessitates an increase in cardiac output that results in increases in the three main determinants of myocardial oxygen demand: heart rate, myocardial contractility, and ventricular work. The approximately sixfold increase in oxygen demands of the left ventricle during heavy exercise is met principally by augmenting coronary blood flow (∼5-fold), as hemoglobin concentration and oxygen extraction (which is already 70–80% at rest) increase only modestly in most species. In contrast, in the right ventricle, oxygen extraction is lower at rest and increases substantially during exercise, similar to skeletal muscle, suggesting fundamental differences in blood flow regulation between these two cardiac chambers. The increase in heart rate also increases the relative time spent in systole, thereby increasing the net extravascular compressive forces acting on the microvasculature within the wall of the left ventricle, in particular in its subendocardial layers. Hence, appropriate adjustment of coronary vascular resistance is critical for the cardiac response to exercise. Coronary resistance vessel tone results from the culmination of myriad vasodilator and vasoconstrictors influences, including neurohormones and endothelial and myocardial factors. Unraveling of the integrative mechanisms controlling coronary vasodilation in response to exercise has been difficult, in part due to the redundancies in coronary vasomotor control and differences between animal species. Exercise training is associated with adaptations in the coronary microvasculature including increased arteriolar densities and/or diameters, which provide a morphometric basis for the observed increase in peak coronary blood flow rates in exercise-trained animals. In larger animals trained by treadmill exercise, the formation of new capillaries maintains capillary density at a level commensurate with the degree of exercise-induced physiological myocardial hypertrophy. Nevertheless, training alters the distribution of coronary vascular resistance so that more capillaries are recruited, resulting in an increase in the permeability-surface area product without a change in capillary numerical density. Maintenance of α- and ß-adrenergic tone in the presence of lower circulating catecholamine levels appears to be due to increased receptor responsiveness to adrenergic stimulation. Exercise training also alters local control of coronary resistance vessels. Thus arterioles exhibit increased myogenic tone, likely due to a calcium-dependent protein kinase C signaling-mediated alteration in voltage-gated calcium channel activity in response to stretch. Conversely, training augments endothelium-dependent vasodilation throughout the coronary microcirculation. This enhanced responsiveness appears to result principally from an increased expression of nitric oxide (NO) synthase. Finally, physical conditioning decreases extravascular compressive forces at rest and at comparable levels of exercise, mainly because of a decrease in heart rate. Impedance to coronary inflow due to an epicardial coronary artery stenosis results in marked redistribution of myocardial blood flow during exercise away from the subendocardium towards the subepicardium. However, in contrast to the traditional view that myocardial ischemia causes maximal microvascular dilation, more recent studies have shown that the coronary microvessels retain some degree of vasodilator reserve during exercise-induced ischemia and remain responsive to vasoconstrictor stimuli. These observations have required reassessment of the principal sites of resistance to blood flow in the microcirculation. A significant fraction of resistance is located in small arteries that are outside the metabolic control of the myocardium but are sensitive to shear and nitrovasodilators. The coronary collateral system embodies a dynamic network of interarterial vessels that can undergo both long- and short-term adjustments that can modulate blood flow to the dependent myocardium. Long-term adjustments including recruitment and growth of collateral vessels in response to arterial occlusion are time dependent and determine the maximum blood flow rates available to the collateral-dependent vascular bed during exercise. Rapid short-term adjustments result from active vasomotor activity of the collateral vessels. Mature coronary collateral vessels are responsive to vasodilators such as nitroglycerin and atrial natriuretic peptide, and to vasoconstrictors such as vasopressin, angiotensin II, and the platelet products serotonin and thromboxane A2. During exercise, ß-adrenergic activity and endothelium-derived NO and prostanoids exert vasodilator influences on coronary collateral vessels. Importantly, alterations in collateral vasomotor tone, e.g., by exogenous vasopressin, inhibition of endogenous NO or prostanoid production, or increasing local adenosine production can modify collateral conductance, thereby influencing the blood supply to the dependent myocardium. In addition, vasomotor activity in the resistance vessels of the collateral perfused vascular bed can influence the volume and distribution of blood flow within the collateral zone. Finally, there is evidence that vasomotor control of resistance vessels in the normally perfused regions of collateralized hearts is altered, indicating that the vascular adaptations in hearts with a flow-limiting coronary obstruction occur at a global as well as a regional level. Exercise training does not stimulate growth of coronary collateral vessels in the normal heart. However, if exercise produces ischemia, which would be absent or minimal under resting conditions, there is evidence that collateral growth can be enhanced. In addition to ischemia, the pressure gradient between vascular beds, which is a determinant of the flow rate and therefore the shear stress on the collateral vessel endothelium, may also be important in stimulating growth of collateral vessels.
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Maasrani M, Verhoye JP, Corbineau H, Drochon A. Analog electrical model of the coronary circulation in case of multiple revascularizations. Ann Biomed Eng 2008; 36:1163-74. [PMID: 18425580 DOI: 10.1007/s10439-008-9500-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 04/07/2008] [Indexed: 12/01/2022]
Abstract
In this work, we propose an analog electrical model of the coronary circulation for patients with obstructive disease undergoing revascularization. In this clinical situation, the collateral circulation to the occluded artery is difficult to ascertain via preoperative measurements and well-developed collaterals might induce long-term restenosis of the revascularized artery due to flow competition mechanisms. The proposed model allows an original biomechanical analysis of per-operative hemodynamic data in order to assess quantitative evaluation of pressures and flows inside the native stenosed arteries, the collateral network and the bypass grafts. Average cardiac cycle values are analysed. In the case of 3-vessel disease and chronic occlusion of the right coronary artery, the quantitative results confirm the protective effects of the collateral flows in the pathological situation, but also show that the revascularization of the occluded right artery is fully justified since the collateral flows remain low, even when the left territory is revascularized. The model thus provides a computational tool to evaluate therapeutic strategies for each patient.
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Affiliation(s)
- Mahmoud Maasrani
- Department of Biomedical Engineering, IUL University, Beirut, Lebanon
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Waves in arteries: A review of wave intensity analysis in the systemic and coronary circulations. Artery Res 2008. [DOI: 10.1016/j.artres.2008.02.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Van Herck PL, Carlier SG, Claeys MJ, Haine SE, Gorissen P, Miljoen H, Bosmans JM, Vrints CJ. Coronary microvascular dysfunction after myocardial infarction: increased coronary zero flow pressure both in the infarcted and in the remote myocardium is mainly related to left ventricular filling pressure. Heart 2007; 93:1231-7. [PMID: 17395671 PMCID: PMC2000925 DOI: 10.1136/hrt.2006.100818] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVE To investigate the underlying mechanisms of a decreased coronary flow reserve after myocardial infarction (MI) by analysing the characteristics of the diastolic hyperaemic coronary pressure-flow relationship. DESIGN Prospective study. SETTING Tertiary care hospital. PATIENTS 68 patients with a recent MI and 27 patients with stable angina pectoris (AP; control group). MAIN OUTCOME MEASURES The intercept with the pressure axis (the zero flow pressure or Pzf) and slope index of the pressure-flow relationship (SIPF) were calculated from the simultaneously recorded hyperaemic intracoronary blood flow velocity and aortic pressure after successful coronary stenting. RESULTS A stepwise increase in Pzf from AP (14.6 (8.0) mm Hg), over non-Q-wave MI (22.5 (9.1) mm Hg), to Q-wave MI (37.1 (12.9) mm Hg; p<0.001) was observed. Similar changes in Pzf were found in a reference artery perfusing the non-infarcted myocardium. Multivariate analysis showed that in both regions the left ventricular end-diastolic pressure (LVEDP) was the most important determinant of the Pzf. The SIPF was not statistically different in the treated vessel between patients with MI and AP, but was increased in MI patients with a markedly increased LVEDP. CONCLUSIONS After an MI, the coronary pressure-flow relationship is shifted to the right both in the infarcted and in the non-infarcted remote myocardium, as shown by the increased Pzf. The correlation with Pzf suggests that elevated left ventricular filling pressures contribute to the impediment of myocardial perfusion in patients with infarction.
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Affiliation(s)
- P L Van Herck
- Department of Cardiology, Antwerp University Hospital, Edegem, Belgium.
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Li XF, Wang YP. Laser Doppler flowmetry for assessment of myocardial microperfusion in the beating rat heart. Vascul Pharmacol 2007; 46:207-14. [PMID: 17127098 DOI: 10.1016/j.vph.2006.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2006] [Accepted: 10/03/2006] [Indexed: 11/25/2022]
Abstract
Although laser Doppler flowmetry (LDF) is widely used for measuring microperfusion, it is rarely used to measure coronary microcirculation. The present in vivo study investigated the use of LDF to measure myocardial microperfusion in beating rat hearts. Ascending aortic flow and other hemodynamic parameters were simultaneously recorded. A needle probe with a holder was adhered to the epicardium of the left ventricular myocardium close to the left anterior descending coronary artery in an anaesthetized open-chest rat. Myocardial microperfusion was measured in response to bolus intravenous administration of both two representative vasodilators (captopril and nifedipine) and a vasoconstrictor (pituitrin). Myocardial microperfusion was found to be predominately diastolic, and in an opposing phase to the ascending aortic flow. Captopril (5 or 10 mg/kg) increased the initial myocardial microperfusion phase. Nifedipine at 75 microg/kg caused a sustained myocardial microperfusion elevation with a peak increase of 7.1+/-1.1%, but this was not observed using 150 microg/kg nifedipine. Both drugs caused an increase in the cardiac index. In contrast, myocardial microperfusion decreased (28.7+/-0.1% maximum decrease) in response to 1 IU/kg pituitrin. In conclusion, LDF provided a means of assessing myocardial microperfusion in beating rat hearts, and can be applied to evaluate the coronary microcirculation response to drugs.
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Affiliation(s)
- Xiao-Fen Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China
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Bovendeerd PHM, Borsje P, Arts T, van De Vosse FN. Dependence of intramyocardial pressure and coronary flow on ventricular loading and contractility: a model study. Ann Biomed Eng 2006; 34:1833-45. [PMID: 17048105 PMCID: PMC1705493 DOI: 10.1007/s10439-006-9189-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Accepted: 08/29/2006] [Indexed: 12/01/2022]
Abstract
The phasic coronary arterial inflow during the normal cardiac cycle has been explained with simple (waterfall, intramyocardial pump) models, emphasizing the role of ventricular pressure. To explain changes in isovolumic and low afterload beats, these models were extended with the effect of three-dimensional wall stress, nonlinear characteristics of the coronary bed, and extravascular fluid exchange. With the associated increase in the number of model parameters, a detailed parameter sensitivity analysis has become difficult. Therefore we investigated the primary relations between ventricular pressure and volume, wall stress, intramyocardial pressure and coronary blood flow, with a mathematical model with a limited number of parameters. The model replicates several experimental observations: the phasic character of coronary inflow is virtually independent of maximum ventricular pressure, the amplitude of the coronary flow signal varies about proportionally with cardiac contractility, and intramyocardial pressure in the ventricular wall may exceed ventricular pressure. A parameter sensitivity analysis shows that the normalized amplitude of coronary inflow is mainly determined by contractility, reflected in ventricular pressure and, at low ventricular volumes, radial wall stress. Normalized flow amplitude is less sensitive to myocardial coronary compliance and resistance, and to the relation between active fiber stress, time, and sarcomere shortening velocity.
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Affiliation(s)
- Peter H M Bovendeerd
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands.
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Westerhof N, Boer C, Lamberts RR, Sipkema P. Cross-Talk Between Cardiac Muscle and Coronary Vasculature. Physiol Rev 2006; 86:1263-308. [PMID: 17015490 DOI: 10.1152/physrev.00029.2005] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cardiac muscle and the coronary vasculature are in close proximity to each other, and a two-way interaction, called cross-talk, exists. Here we focus on the mechanical aspects of cross-talk including the role of the extracellular matrix. Cardiac muscle affects the coronary vasculature. In diastole, the effect of the cardiac muscle on the coronary vasculature depends on the (changes in) muscle length but appears to be small. In systole, coronary artery inflow is impeded, or even reversed, and venous outflow is augmented. These systolic effects are explained by two mechanisms. The waterfall model and the intramyocardial pump model are based on an intramyocardial pressure, assumed to be proportional to ventricular pressure. They explain the global effects of contraction on coronary flow and the effects of contraction in the layers of the heart wall. The varying elastance model, the muscle shortening and thickening model, and the vascular deformation model are based on direct contact between muscles and vessels. They predict global effects as well as differences on flow in layers and flow heterogeneity due to contraction. The relative contributions of these two mechanisms depend on the wall layer (epi- or endocardial) and type of contraction (isovolumic or shortening). Intramyocardial pressure results from (local) muscle contraction and to what extent the interstitial cavity contracts isovolumically. This explains why small arterioles and venules do not collapse in systole. Coronary vasculature affects the cardiac muscle. In diastole, at physiological ventricular volumes, an increase in coronary perfusion pressure increases ventricular stiffness, but the effect is small. In systole, there are two mechanisms by which coronary perfusion affects cardiac contractility. Increased perfusion pressure increases microvascular volume, thereby opening stretch-activated ion channels, resulting in an increased intracellular Ca2+transient, which is followed by an increase in Ca2+sensitivity and higher muscle contractility (Gregg effect). Thickening of the shortening cardiac muscle takes place at the expense of the vascular volume, which causes build-up of intracellular pressure. The intracellular pressure counteracts the tension generated by the contractile apparatus, leading to lower net force. Therefore, cardiac muscle contraction is augmented when vascular emptying is facilitated. During autoregulation, the microvasculature is protected against volume changes, and the Gregg effect is negligible. However, the effect is present in the right ventricle, as well as in pathological conditions with ineffective autoregulation. The beneficial effect of vascular emptying may be reduced in the presence of a stenosis. Thus cardiac contraction affects vascular diameters thereby reducing coronary inflow and enhancing venous outflow. Emptying of the vasculature, however, enhances muscle contraction. The extracellular matrix exerts its effect mainly on cardiac properties rather than on the cross-talk between cardiac muscle and coronary circulation.
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Affiliation(s)
- Nico Westerhof
- Laboratory of Physiology and Department of Anesthesiology, Institute for Cardiovascular Research Vrije Universiteit, VU University Medical Center, Amsterdam, The Netherlands
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Rodriguez I, Ennis DB, Wen H. Noninvasive measurement of myocardial tissue volume change during systolic contraction and diastolic relaxation in the canine left ventricle. Magn Reson Med 2006; 55:484-90. [PMID: 16408273 PMCID: PMC2887312 DOI: 10.1002/mrm.20786] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In coronary circulation the flow in epicardial arteries and veins is observed to be pulsatile and out of phase with each other. Theoretical considerations predict that this phenomenon extends to all levels of the vascular tree and leads to a cyclic fluctuation of regional tissue volume. Intramyocardial tissue volume change between end-systole and end-diastole was measured noninvasively with MRI in 10 closed-chest beagles. The displacement encoding with stimulated-echo technique was used to obtain pixel-by-pixel tissue displacement field between end-diastole and end-systole and vice versa in the midlevel left ventricle, from which the 3D strain matrix and volume changes were calculated. The volume change was between 0.8+/-0.5% (mean+/-STD) in the epicardial layer and 1.5+/-0.6% in the subendocardial layer of the left ventricle. Tissue volume fluctuation reflects the amount of arterial inflow in a heartbeat under the assumption that regional arterial inflow and venous outflow have little time overlap. The corresponding perfusion level was estimated to be from (1.0+/-0.6) ml/min/g in the epicardial layer to (1.7+/-0.6) ml/min/g in the subendocardial layer, in good agreement with microsphere measurements in the same dog model. The result supports the notion of high arterial resistance at the microvascular level from intramyocardial pressure during systole.
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Affiliation(s)
- Ignacio Rodriguez
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Daniel B. Ennis
- Department of Radiology, Stanford University, Palo Alto, California, USA
| | - Han Wen
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
- Correspondence to: Han Wen, Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1061, USA.
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Kaimovitz B, Lanir Y, Kassab GS. Large-scale 3-D geometric reconstruction of the porcine coronary arterial vasculature based on detailed anatomical data. Ann Biomed Eng 2006; 33:1517-35. [PMID: 16341920 DOI: 10.1007/s10439-005-7544-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Accepted: 07/20/2005] [Indexed: 10/25/2022]
Abstract
The temporal and spatial distribution of coronary blood flow, pressure, and volume are determined by the branching pattern and three-dimensional (3-D) geometry of the coronary vasculature, and by the mechanics of heart wall and vascular tone. Consequently, a realistic simulation of coronary blood flow requires, as a first step, an accurate representation of the coronary vasculature in a 3-D model of the beating heart. In the present study, a large-scale stochastic reconstruction of the asymmetric coronary arterial trees (right coronary artery, RCA; left anterior descending, LAD; and left circumflex, LCx) of the porcine heart has been carried out to set the stage for future hemodynamic analysis. The model spans the entire coronary arterial tree down to the capillary vessels. The 3-D tree structure was reconstructed initially in rectangular slab geometry by means of global geometrical optimization using parallel simulated annealing (SA) algorithm. The SA optimization was subject to constraints prescribed by previously measured morphometric features of the coronary arterial trees. Subsequently, the reconstructed trees were mapped onto a prolate spheroid geometry of the heart. The transformed geometry was determined through least squares minimization of the related changes in both segments lengths and their angular characteristics. Vessel diameters were assigned based on a novel representation of diameter asymmetry along bifurcations. The reconstructed RCA, LAD and LCx arterial trees show qualitative resemblance to native coronary networks, and their morphological statistics are consistent with the measured data. The present model constitutes the first most extensive reconstruction of the entire coronary arterial system which will serve as a geometric foundation for future studies of flow in an anatomically accurate 3-D coronary vascular model.
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Affiliation(s)
- Benjamin Kaimovitz
- Department of Biomedical Engineering, Israel Institute of Technology, Haifa, Israel
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