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O'Meara S, Cunnane EM, Croghan SM, Cunnane CV, Walsh MT, O'Brien FJ, Davis NF. Mechanical characteristics of the ureter and clinical implications. Nat Rev Urol 2024; 21:197-213. [PMID: 38102385 DOI: 10.1038/s41585-023-00831-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2023] [Indexed: 12/17/2023]
Abstract
The ureteric wall is a complex multi-layered structure. The ureter shows variation in passive mechanical properties, histological morphology and insertion forces along the anatomical length. Ureter mechanical properties also vary depending on the direction of tensile testing and the anatomical region tested. Compliance is greatest in the proximal ureter and lower in the distal ureter, which contributes to the role of the ureter as a high-resistance sphincter. Similar to other human tissues, the ureteric wall remodels with age, resulting in changes to the mechanical properties. The passive mechanical properties of the ureter vary between species, and variation in tissue storage and testing methods limits comparison across some studies. Knowledge of the morphological and mechanical properties of the ureteric wall can aid in understanding urine transport and safety thresholds in surgical techniques. Indeed, various factors alter the forces required to insert access sheaths or scopes into the ureter, including sheath diameter, safety wires and medications. Future studies on human ureteric tissue both in vivo and ex vivo are required to understand the mechanical properties of the ureter and how forces influence these properties. Testing of instrument insertion forces in humans with a focus on defining safe upper limits and techniques to reduce trauma are also needed. Last, evaluation of dilatation limits in the mid and proximal ureter and clarification of tensile strength anisotropy in human specimens are necessary.
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Affiliation(s)
- Sorcha O'Meara
- Department of Surgery, Royal College of Surgeons of Ireland (RCSI), Dublin, Ireland.
- Department of Urology, Blackrock Clinic, Blackrock, Co., Dublin, Ireland.
| | - Eoghan M Cunnane
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, University of Limerick, Limerick, Ireland
| | - Stefanie M Croghan
- Department of Surgery, Royal College of Surgeons of Ireland (RCSI), Dublin, Ireland
- Department of Urology, Blackrock Clinic, Blackrock, Co., Dublin, Ireland
| | - Connor V Cunnane
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, University of Limerick, Limerick, Ireland
| | - Michael T Walsh
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, University of Limerick, Limerick, Ireland
| | - Fergal J O'Brien
- Tissue Engineering Research Group, Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
- Advanced Materials and Bioengineering Research Centre (AMBER), RCSI and TCD, Dublin, Ireland
| | - Niall F Davis
- Department of Surgery, Royal College of Surgeons of Ireland (RCSI), Dublin, Ireland
- Department of Urology, Blackrock Clinic, Blackrock, Co., Dublin, Ireland
- Department of Urology and Transplant Surgery, Beaumont Hospital, Dublin, Ireland
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2
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Naessens DMP, de Vos J, Richard E, Wilhelmus MMM, Jongenelen CAM, Scholl ER, van der Wel NN, Heijst JA, Teunissen CE, Strijkers GJ, Coolen BF, VanBavel E, Bakker ENTP. Effect of long-term antihypertensive treatment on cerebrovascular structure and function in hypertensive rats. Sci Rep 2023; 13:3481. [PMID: 36859481 PMCID: PMC9977931 DOI: 10.1038/s41598-023-30515-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/24/2023] [Indexed: 03/03/2023] Open
Abstract
Midlife hypertension is an important risk factor for cognitive impairment and dementia, including Alzheimer's disease. We investigated the effects of long-term treatment with two classes of antihypertensive drugs to determine whether diverging mechanisms of blood pressure lowering impact the brain differently. Spontaneously hypertensive rats (SHR) were either left untreated or treated with a calcium channel blocker (amlodipine) or beta blocker (atenolol) until one year of age. The normotensive Wistar Kyoto rat (WKY) was used as a reference group. Both drugs lowered blood pressure equally, while only atenolol decreased heart rate. Cerebrovascular resistance was increased in SHR, which was prevented by amlodipine but not atenolol. SHR showed a larger carotid artery diameter with impaired pulsatility, which was prevented by atenolol. Cerebral arteries demonstrated inward remodelling, stiffening and endothelial dysfunction in SHR. Both treatments similarly improved these parameters. MRI revealed that SHR have smaller brains with enlarged ventricles. In addition, neurofilament light levels were increased in cerebrospinal fluid of SHR. However, neither treatment affected these parameters. In conclusion, amlodipine and atenolol both lower blood pressure, but elicit a different hemodynamic profile. Both medications improve cerebral artery structure and function, but neither drug prevented indices of brain damage in this model of hypertension.
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Affiliation(s)
- Daphne M. P. Naessens
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands ,Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands ,grid.484519.5Amsterdam Neuroscience, Neurovascular Disorders, Amsterdam, The Netherlands
| | - Judith de Vos
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands ,Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands ,grid.484519.5Amsterdam Neuroscience, Neurovascular Disorders, Amsterdam, The Netherlands
| | - Edo Richard
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Public and Occupational Health, Amsterdam, The Netherlands ,grid.10417.330000 0004 0444 9382Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Micha M. M. Wilhelmus
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location Vrije Universiteit Amsterdam, Anatomy and Neurosciences, Amsterdam, The Netherlands ,grid.484519.5Amsterdam Neuroscience, Neurodegeneration, Amsterdam, The Netherlands
| | - Cornelis A. M. Jongenelen
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location Vrije Universiteit Amsterdam, Anatomy and Neurosciences, Amsterdam, The Netherlands
| | - Edwin R. Scholl
- grid.5650.60000000404654431Amsterdam UMC Location University of Amsterdam, Medical Biology, Electron Microscopy Center Amsterdam, Amsterdam, The Netherlands
| | - Nicole N. van der Wel
- grid.5650.60000000404654431Amsterdam UMC Location University of Amsterdam, Medical Biology, Electron Microscopy Center Amsterdam, Amsterdam, The Netherlands
| | - Johannes A. Heijst
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location Vrije Universiteit Amsterdam, Neurochemistry Laboratory, Clinical Chemistry, Amsterdam, The Netherlands
| | - Charlotte E. Teunissen
- grid.484519.5Amsterdam Neuroscience, Neurodegeneration, Amsterdam, The Netherlands ,grid.509540.d0000 0004 6880 3010Amsterdam UMC Location Vrije Universiteit Amsterdam, Neurochemistry Laboratory, Clinical Chemistry, Amsterdam, The Netherlands ,grid.484519.5Amsterdam Neuroscience, Neuroinfection and -Inflammation, Amsterdam, The Netherlands
| | - Gustav J. Strijkers
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Bram F. Coolen
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands ,Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands
| | - Ed VanBavel
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands ,Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands ,grid.484519.5Amsterdam Neuroscience, Neurovascular Disorders, Amsterdam, The Netherlands
| | - Erik N. T. P. Bakker
- grid.509540.d0000 0004 6880 3010Amsterdam UMC Location University of Amsterdam, Biomedical Engineering and Physics, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands ,Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands ,grid.484519.5Amsterdam Neuroscience, Neurovascular Disorders, Amsterdam, The Netherlands
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Manoj R, Raj Kiran V, Nabeel PM, Sivaprakasam M, Joseph J. Evaluation of Nonlinear Wave Separation Method to Assess Reflection Transit Time: A Virtual Patient Study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:5551-5554. [PMID: 34892382 DOI: 10.1109/embc46164.2021.9630464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Conventional methods to calculate reflection transit time (RTT) is based on pulse counter analysis. An alternative to this approach is separating forward and backward components from a pulse waveform to calculate the RTT. State-of-the-art in wave separation requires simultaneously measured pressure and flow velocity waveforms. Practically, getting a simultaneous measurement from a single arterial site has its limitations, and this has made the translation of wave separation methods to clinical practice difficult. We propose a new method of wave separation analysis that requires only a single pulse waveform measurement using a multi-Gaussian decomposition approach. The novelty of the method is that it does not require any measured or modelled flow velocity waveform. In this method, the pulse waveform is decomposed into the sum of Gaussians and reconstructed based on model criteria. RTT is calculated as the time difference between normalized forward and backward waveform. The method's feasibility in using RTT as a potential surrogate is demonstrated on 105 diverse selections of virtual subjects. The results were statistically significant and had a strong correlation (r>79, p<0.0001) against clinically approved artery stiffness markers such as Peterson's elastic modulus (Ep), pulse wave velocity (PWV), specific stiffness index (β), and arterial compliance (AC). Out of all the elasticity markers, a better correlation was found against AC.Clinical Relevance-This simulation study supplements the evidence for the dependence of pulse wave reflections on arterial stiffness. It provides a new method to study wave reflections using only a single pulse waveform.
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van der Bruggen MM, Reesink KD, Spronck PJM, Bitsch N, Hameleers J, Megens RTA, Schalkwijk CG, Delhaas T, Spronck B. An integrated set-up for ex vivo characterisation of biaxial murine artery biomechanics under pulsatile conditions. Sci Rep 2021; 11:2671. [PMID: 33514757 PMCID: PMC7846753 DOI: 10.1038/s41598-021-81151-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/07/2020] [Indexed: 01/19/2023] Open
Abstract
Ex vivo characterisation of arterial biomechanics enables detailed discrimination of the various cellular and extracellular contributions to arterial stiffness. However, ex vivo biomechanical studies are commonly performed under quasi-static conditions, whereas dynamic biomechanical behaviour (as relevant in vivo) may differ substantially. Hence, we aim to (1) develop an integrated set-up for quasi-static and dynamic biaxial biomechanical testing, (2) quantify set-up reproducibility, and (3) illustrate the differences in measured arterial stiffness between quasi-static and dynamic conditions. Twenty-two mouse carotid arteries were mounted between glass micropipettes and kept fully vasodilated. While recording pressure, axial force (F), and inner diameter, arteries were exposed to (1) quasi-static pressure inflation from 0 to 200 mmHg; (2) 300 bpm dynamic pressure inflation (peaking at 80/120/160 mmHg); and (3) axial stretch (λz) variation at constant pressures of 10/60/100/140/200 mmHg. Measurements were performed in duplicate. Single-point pulse wave velocities (PWV; Bramwell-Hill) and axial stiffness coefficients (cax = dF/dλz) were calculated at the in vivo value of λz. Within-subject coefficients of variation were ~ 20%. Dynamic PWVs were consistently higher than quasi-static PWVs (p < 0.001); cax increased with increasing pressure. We demonstrated the feasibility of ex vivo biomechanical characterisation of biaxially-loaded murine carotid arteries under pulsatile conditions, and quantified reproducibility allowing for well-powered future study design.
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Affiliation(s)
- Myrthe M van der Bruggen
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Room 3.359, 6229ER, Maastricht, The Netherlands
| | - Koen D Reesink
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Room 3.359, 6229ER, Maastricht, The Netherlands
| | | | - Nicole Bitsch
- Muroidean Facility, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Jeroen Hameleers
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Room 3.359, 6229ER, Maastricht, The Netherlands
| | - Remco T A Megens
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Room 3.359, 6229ER, Maastricht, The Netherlands.,Institute for Cardiovascular Prevention, Ludwig-Maximilians-Universität, Munich, Germany
| | - Casper G Schalkwijk
- Department of Internal Medicine, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Room 3.359, 6229ER, Maastricht, The Netherlands
| | - Bart Spronck
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Room 3.359, 6229ER, Maastricht, The Netherlands. .,Department of Biomedical Engineering, School of Engineering & Applied Science, Yale University, New Haven, CT, USA.
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Impaired Glymphatic Transport in Spontaneously Hypertensive Rats. J Neurosci 2019; 39:6365-6377. [PMID: 31209176 DOI: 10.1523/jneurosci.1974-18.2019] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 03/31/2019] [Accepted: 05/30/2019] [Indexed: 12/21/2022] Open
Abstract
The glymphatic system is a brainwide CSF transport system that uses the perivascular space for fast inflow of CSF. Arterial pulsations are a major driver of glymphatic CSF inflow, and hypertension that causes vascular pathologies, such as arterial stiffening and perivascular alterations, may impede the inflow. We used dynamic contrast-enhanced MRI to assess the effect of hypertension on glymphatic transport kinetics in male young and adult spontaneously hypertensive (SHR) rats compared with age-matched normotensive Wistar-Kyoto rats (WKY). We anesthetized the rats with dexmedetomidine/isoflurane and infused paramagnetic contrast (Gd-DOTA) into the cisterna magna during dynamic contrast-enhanced MRI to quantify glymphatic transport kinetics. Structural MRI analysis showed that cerebroventricular volumes are larger and brain volumes significantly smaller in SHR compared with WKY rats, regardless of age. We observed ventricular reflux of Gd-DOTA in SHR rats only, indicating abnormal CSF flow dynamics secondary to innate hydrocephalus. One-tissue compartment analysis revealed impeded glymphatic transport of Gd-DOTA in SHR compared with WKY rats in both age groups, implying that glymphatic transport, including solute clearance from brain parenchyma, is impaired during evolving hypertension in young SHR, an effect that worsens in states of chronic hypertension. The study demonstrates the suppression of glymphatic clearance in SHR rats and thus offers new insight into the coexistence of hypertension and concomitant vascular pathologies in Alzheimer's disease. The study further highlights the importance of considering the distribution of tracers in the CSF compartment in the analysis of the glymphatic system.SIGNIFICANCE STATEMENT The glymphatic system contributes to the removal of amyloid β from the brain and is disrupted in Alzheimer's disease and aging. Using a rat model of hypertension, we measured gross CSF flow and tracked glymphatic influx and efflux rates with dynamic contrast-enhanced MRI, showing that glymphatic transport is compromised in both early and advanced stages of hypertension. The study provides a new perspective on the importance for brain metabolite and fluid homeostasis of maintaining healthy blood vessels, an increasingly pertinent issue in an aging population that in part may explain the link between vascular pathology and Alzheimer's disease.
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Model-based analysis of arterial pulse signals for tracking changes in arterial wall parameters: a pilot study. Biomech Model Mechanobiol 2019; 18:1629-1638. [PMID: 31073807 DOI: 10.1007/s10237-019-01165-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
Abstract
Arterial wall parameters (i.e., radius and viscoelasticity) are prognostic markers for cardiovascular diseases (CVD), but their current monitoring systems are too complex for home use. Our objective was to investigate whether model-based analysis of arterial pulse signals allows tracking changes in arterial wall parameters using a microfluidic-based tactile sensor. The sensor was used to measure an arterial pulse signal. A data-processing algorithm was utilized to process the measured pulse signal to obtain the radius waveform and its first-order and second-order derivatives, and extract their key features. A dynamic system model of the arterial wall and a hemodynamic model of the blood flow were developed to interpret the extracted key features for estimating arterial wall parameters, with no need of calibration. Changes in arterial wall parameters were introduced to healthy subjects ([Formula: see text]) by moderate exercise. The estimated values were compared between pre-exercise and post-exercise for significant difference ([Formula: see text]). The estimated changes in the radius, elasticity and viscosity were consistent with the findings in the literature (between pre-exercise and 1 min post-exercise: - 11% ± 4%, 55% ± 38% and 28% ± 11% at the radial artery; - 7% ± 3%, 36% ± 28% and 16% ± 8% at the carotid artery). The model-based analysis allows tracking changes in arterial wall parameters using a microfluidic-based tactile sensor. This study shows the potential of developing a solution to at-home monitoring of the cardiovascular system for early detection, timely intervention and treatment assessment of CVD.
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Spronck B, Humphrey J. Arterial Stiffness: Different Metrics, Different Meanings. J Biomech Eng 2019; 141:2731248. [PMID: 30985880 PMCID: PMC6808013 DOI: 10.1115/1.4043486] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Indexed: 12/18/2022]
Abstract
Findings from basic science and clinical studies agree that arterial stiffness is fundamental to both the mechanobiology and the biomechanics that dictate vascular health and disease. There is, therefore, an appropriately growing literature on arterial stiffness. Perusal of the literature reveals, however, that many different methods and metrics are used to quantify arterial stiffness, and reported values often differ by orders of magnitude and have different meanings. Without clear definitions and an understanding of possible inter-relations therein, it is increasingly difficult to integrate results from the literature to glean true understanding. In this paper, we briefly review methods that are used to infer values of arterial stiffness that span studies on isolated cells, excised intact vessels, and clinical assessments. We highlight similarities and differences and identify a single theoretical approach that can be used across scales and applications and thus could help to unify future results. We conclude by emphasizing the need to move toward a synthesis of many disparate reports, for only in this way will we be able to move from our current fragmented understanding to a true appreciation of how vascular cells maintain, remodel, or repair the arteries that are fundamental to cardiovascular properties and function.
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Affiliation(s)
- Bart Spronck
- Department of Biomedical Engineering Yale University, New Haven, CT, USA
| | - Jay Humphrey
- Department of Biomedical Engineering Yale University, New Haven, CT, USA; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
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Abstract
In patients with uncomplicated essential hypertension, cardiac output remains within normal ranges and intravascular volume is normal or low, assuming the presence of a sufficient Windkessel effect and usual resistance and compliance calculations. However, mean circulatory pressure is elevated in these patients. In addition, vascular resistance is augmented, and most importantly, the viscoelasticity of the cardiovascular system is substantially impaired. Such considerations are essential to understanding the mechanisms behind carotid-femoral arterial stiffness, a major risk factor in individuals with hypertension. Arterial stiffness, measured from pulse wave velocity, is substantially increased in hypertension even independently of blood pressure levels. Structural vascular changes and endothelial dysfunction are consistently associated with vessel impairments in animal models of hypertension. Increased arterial stiffness has a major effect on pulse pressure (the difference between systolic and diastolic blood pressure), wave reflections, kidney function, and above all, cardiovascular risk. This increased cardiovascular risk is particularly deleterious in patients with hypertension and/or type 2 diabetes mellitus, who are at risk of both renal and cardiovascular events. In this Review, we discuss the importance of arterial stiffness in the diagnosis and management of hypertension and the need for new approaches for the treatment of hypertension in patients with or without diabetes and/or renal impairment.
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Lacolley P, Regnault V, Segers P, Laurent S. Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease. Physiol Rev 2017; 97:1555-1617. [DOI: 10.1152/physrev.00003.2017] [Citation(s) in RCA: 332] [Impact Index Per Article: 47.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 05/15/2017] [Accepted: 05/26/2017] [Indexed: 12/18/2022] Open
Abstract
The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.
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Affiliation(s)
- Patrick Lacolley
- INSERM, U1116, Vandœuvre-lès-Nancy, France; Université de Lorraine, Nancy, France; IBiTech-bioMMeda, Department of Electronics and Information Systems, Ghent University, Gent, Belgium; Department of Pharmacology, European Georges Pompidou Hospital, Assistance Publique Hôpitaux de Paris, France; PARCC INSERM, UMR 970, Paris, France; and University Paris Descartes, Paris, France
| | - Véronique Regnault
- INSERM, U1116, Vandœuvre-lès-Nancy, France; Université de Lorraine, Nancy, France; IBiTech-bioMMeda, Department of Electronics and Information Systems, Ghent University, Gent, Belgium; Department of Pharmacology, European Georges Pompidou Hospital, Assistance Publique Hôpitaux de Paris, France; PARCC INSERM, UMR 970, Paris, France; and University Paris Descartes, Paris, France
| | - Patrick Segers
- INSERM, U1116, Vandœuvre-lès-Nancy, France; Université de Lorraine, Nancy, France; IBiTech-bioMMeda, Department of Electronics and Information Systems, Ghent University, Gent, Belgium; Department of Pharmacology, European Georges Pompidou Hospital, Assistance Publique Hôpitaux de Paris, France; PARCC INSERM, UMR 970, Paris, France; and University Paris Descartes, Paris, France
| | - Stéphane Laurent
- INSERM, U1116, Vandœuvre-lès-Nancy, France; Université de Lorraine, Nancy, France; IBiTech-bioMMeda, Department of Electronics and Information Systems, Ghent University, Gent, Belgium; Department of Pharmacology, European Georges Pompidou Hospital, Assistance Publique Hôpitaux de Paris, France; PARCC INSERM, UMR 970, Paris, France; and University Paris Descartes, Paris, France
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Lee P, Carlson BE, Chesler N, Olufsen MS, Qureshi MU, Smith NP, Sochi T, Beard DA. Heterogeneous mechanics of the mouse pulmonary arterial network. Biomech Model Mechanobiol 2016; 15:1245-61. [PMID: 26792789 PMCID: PMC4956606 DOI: 10.1007/s10237-015-0757-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/25/2015] [Indexed: 10/22/2022]
Abstract
Individualized modeling and simulation of blood flow mechanics find applications in both animal research and patient care. Individual animal or patient models for blood vessel mechanics are based on combining measured vascular geometry with a fluid structure model coupling formulations describing dynamics of the fluid and mechanics of the wall. For example, one-dimensional fluid flow modeling requires a constitutive law relating vessel cross-sectional deformation to pressure in the lumen. To investigate means of identifying appropriate constitutive relationships, an automated segmentation algorithm was applied to micro-computerized tomography images from a mouse lung obtained at four different static pressures to identify the static pressure-radius relationship for four generations of vessels in the pulmonary arterial network. A shape-fitting function was parameterized for each vessel in the network to characterize the nonlinear and heterogeneous nature of vessel distensibility in the pulmonary arteries. These data on morphometric and mechanical properties were used to simulate pressure and flow velocity propagation in the network using one-dimensional representations of fluid and vessel wall mechanics. Moreover, wave intensity analysis was used to study effects of wall mechanics on generation and propagation of pressure wave reflections. Simulations were conducted to investigate the role of linear versus nonlinear formulations of wall elasticity and homogeneous versus heterogeneous treatments of vessel wall properties. Accounting for heterogeneity, by parameterizing the pressure/distention equation of state individually for each vessel segment, was found to have little effect on the predicted pressure profiles and wave propagation compared to a homogeneous parameterization based on average behavior. However, substantially different results were obtained using a linear elastic thin-shell model than were obtained using a nonlinear model that has a more physiologically realistic pressure versus radius relationship.
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Affiliation(s)
- Pilhwa Lee
- Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA
| | - Brian E Carlson
- Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA
| | - Naomi Chesler
- Department of Biomedical Engineering, University of Wisconsin-Madison, 2146 ECB; 1550 Engineering Drive, Madison, WI, 53706-1609, USA
| | - Mette S Olufsen
- Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC, 27502, USA
| | - M Umar Qureshi
- Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC, 27502, USA
| | - Nicolas P Smith
- Imaging Sciences and Biomedical Engineering Division, St Thomas' Hospital, King's College London, London, SE1 7EH, UK
- Faculty of Engineering, 20 Symonds St, Auckland, 1010, New Zealand
| | - Taha Sochi
- Imaging Sciences and Biomedical Engineering Division, St Thomas' Hospital, King's College London, London, SE1 7EH, UK
| | - Daniel A Beard
- Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA.
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Safar ME. A reappraisal of clinical research on arterial stiffness in hypertension in France. ACTA ACUST UNITED AC 2016; 10:482-8. [PMID: 27189796 DOI: 10.1016/j.jash.2016.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/25/2016] [Accepted: 04/06/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Michel E Safar
- Diagnosis and Therapeutic Center, AP-HP, Paris Descartes University, Paris, France.
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12
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Boekhoven RW, Peters MFJ, Rutten MCM, van Sambeek MR, van de Vosse FN, Lopata RGP. Inflation and Bi-Axial Tensile Testing of Healthy Porcine Carotid Arteries. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:574-585. [PMID: 26598396 DOI: 10.1016/j.ultrasmedbio.2015.09.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 09/16/2015] [Accepted: 09/16/2015] [Indexed: 06/05/2023]
Abstract
Knowledge of the intrinsic material properties of healthy and diseased arterial tissue components is of great importance in diagnostics. This study describes an in vitro comparison of 13 porcine carotid arteries using inflation testing combined with functional ultrasound and bi-axial tensile testing. The measured tissue behavior was described using both a linear, but geometrically non-linear, one-parameter (neo-Hookean) model and a two-parameter non-linear (Demiray) model. The shear modulus estimated using the linear model resulted in good agreement between the ultrasound and tensile testing methods, GUS = 25 ± 5.7 kPa and GTT = 23 ± 5.4 kPa. No significant correspondence was observed for the non-linear model aUS = 1.0 ± 2.7 kPa vs. aTT = 17 ± 8.8 kPa, p ∼ 0); however, the exponential parameters were in correspondence (bUS = 12 ± 4.2 vs. bTT = 10 ± 1.7, p > 0.05). Estimation of more complex models in vivo is cumbersome considering the sensitivity of the model parameters to small changes in measurement data and the absence of intraluminal pressure data, endorsing the use of a simple, linear model in vivo.
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Affiliation(s)
- Renate W Boekhoven
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Mathijs F J Peters
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Marcel C M Rutten
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Marc R van Sambeek
- Vascular Surgery, Catharina Hospital Eindhoven, Eindhoven, The Netherlands
| | - Frans N van de Vosse
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Richard G P Lopata
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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13
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Yongming P, Zhaowei C, Yichao M, Keyan Z, Liang C, Fangming C, Xiaoping X, Quanxin M, Minli C. Involvement of peroxisome proliferator-activated receptors in cardiac and vascular remodeling in a novel minipig model of insulin resistance and atherosclerosis induced by consumption of a high-fat/cholesterol diet. Cardiovasc Diabetol 2015; 14:6. [PMID: 25592139 PMCID: PMC4300051 DOI: 10.1186/s12933-014-0165-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/27/2014] [Indexed: 11/10/2022] Open
Abstract
Background A long-term high-fat/cholesterol (HFC) diet leads to insulin resistance (IR), which is associated with inflammation, atherosclerosis (AS), cardiac sympathovagal imbalance, and cardiac dysfunction. Peroxisome proliferator-activated receptors (PPARs) and nuclear factor ĸB (NF-κB) are involved in the development of IR-AS. Thus, we elucidated the pathological molecular mechanism of IR-AS by feeding an HFC diet to Tibetan minipigs to induce IR and AS. Methods Male Tibetan minipigs were fed either a normal diet or an HFC diet for 24 weeks. Thereafter, the minipigs were tested for physiological and biochemical blood indices, blood pressure, cardiac function, glucose tolerance, heart rate variability (HRV), and PPAR-associated gene and protein expression levels. Results HFC-fed minipigs exhibited IR through increased body weight, fasting blood glucose levels, plasma cholesterol and its composition, and insulin and free fatty acid (FFA) levels; decreased insulin sensitivity; impaired glucose tolerance; and hypertension. Increased C-reactive protein (CRP) levels, cardiac dysfunction, depressed HRV, and the up-regulation of PPAR expression in the abdominal aorta concomitant with down-regulation in the heart tissue were observed in HFC-fed minipigs. Furthermore, the levels of NF-κBp65, IL-1β, TNF-α, MCP-1, VCAM-1, ICAM-1, MMP-9, and CRP proteins were also significantly increased. Conclusions These data suggest that HFC-fed Tibetan minipigs develop IR and AS and that PPARs are involved in cardiovascular remodeling and impaired function.
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Affiliation(s)
- Pan Yongming
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Cai Zhaowei
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Ma Yichao
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Zhu Keyan
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Chen Liang
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Chen Fangming
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Xu Xiaoping
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Ma Quanxin
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
| | - Chen Minli
- Experimental Animal Research Center, Zhejiang Chinese Medical University, No. 548 Binwen Road, Binjiang District, Hangzhou, 310053, China.
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Abstract
BACKGROUND Patho-physiological and pharmacological studies have consistently noticed that, with the exception of subjects with end-stage renal disease, total intravascular blood volume is not increased in patients with chronic hypertension. METHODS Because the mean circulatory pressure is enhanced in such subjects, it was postulated that the compliance of the cardiovascular system could be abnormally low in this particular population. This simple observation has influenced a great part of our experimental and clinical research directed toward subjects with hypertension and their relationship with the compliance of the vascular system. RESULTS These works started between 1970 and 1980 by methodological investigations and validations followed by analysis of clinical situations that showed that venous and mostly arterial stiffness were significantly increased in hypertensive patients independently of blood pressure level. During the same time, we assessed the role of endothelium on the large arterial wall mechanical properties in normotensive and hypertensive rats. Thereafter more specific directions have been developed, affecting large arteries structure and function and arterial wall remodeling, including their consequences on central and peripheral hemodynamics. In parallel, epidemiological studies identified the pulsatile hemodynamic parameters as major independent predictors of cardiovascular risks. CONCLUSIONS The consequences of these alterations on clinical pharmacology and therapeutics in hypertension are analyzed in detail.
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Affiliation(s)
- Michel E Safar
- Paris Descartes University, AP-HP, Diagnosis and Therapeutic Center, Paris, France;
| | - Bernard I Levy
- PARCC, INSERM U970, AP-HP, Service d'Explorations Fonctionnelles, Hôpital Lariboisière, Paris, France
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15
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Bakker ENTP, Groma G, Spijkers LJA, de Vos J, van Weert A, van Veen H, Everts V, Arribas SM, VanBavel E. Heterogeneity in arterial remodeling among sublines of spontaneously hypertensive rats. PLoS One 2014; 9:e107998. [PMID: 25251068 PMCID: PMC4175999 DOI: 10.1371/journal.pone.0107998] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 08/21/2014] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVES Spontaneously hypertensive rats (SHR) have been used frequently as a model for human essential hypertension. However, both the SHR and its normotensive control, the Wistar Kyoto rat (WKY), consist of genetically different sublines. We tested the hypothesis that the pathophysiology of vascular remodeling in hypertension differs among rat sublines. METHODS AND RESULTS We studied mesenteric resistance arteries of WKY and SHR from three different sources, at 6 weeks and 5 months of age. Sublines of WKY and SHR showed differences in blood pressure, body weight, vascular remodeling, endothelial function, and vessel ultrastructure. Common features in small mesenteric arteries from SHR were an increase in wall thickness, wall-to-lumen ratio, and internal elastic lamina thickness. CONCLUSIONS Endothelial dysfunction, vascular stiffening, and inward remodeling of small mesenteric arteries are not common features of hypertension, but are subline-dependent. Differences in genetic background associate with different types of vascular remodeling in hypertensive rats.
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Affiliation(s)
- Erik N. T. P. Bakker
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands
- * E-mail:
| | - Gergely Groma
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands
| | - Léon J. A. Spijkers
- Department of Vascular Medicine and Nephrology, Academic Medical Center, Amsterdam, the Netherlands
| | - Judith de Vos
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands
| | - Angela van Weert
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands
| | - Henk van Veen
- Van Leeuwenhoek Center for Advanced Microscopy, Department of Cell Biology, Academic Medical Center, Amsterdam, the Netherlands
| | - Vincent Everts
- Van Leeuwenhoek Center for Advanced Microscopy, Department of Cell Biology, Academic Medical Center, Amsterdam, the Netherlands
| | - Silvia M. Arribas
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Ed VanBavel
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands
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16
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Wang Z, Lakes RS, Golob M, Eickhoff JC, Chesler NC. Changes in large pulmonary arterial viscoelasticity in chronic pulmonary hypertension. PLoS One 2013; 8:e78569. [PMID: 24223157 PMCID: PMC3819365 DOI: 10.1371/journal.pone.0078569] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 09/14/2013] [Indexed: 02/06/2023] Open
Abstract
Conduit pulmonary artery (PA) stiffening is characteristic of pulmonary arterial hypertension (PAH) and is an excellent predictor of mortality due to right ventricular (RV) overload. To better understand the impact of conduit PA stiffening on RV afterload, it is critical to examine the arterial viscoelastic properties, which require measurements of elasticity (energy storage behavior) and viscosity (energy dissipation behavior). Here we hypothesize that PAH leads to frequency-dependent changes in arterial stiffness (related to elasticity) and damping ratio (related to viscosity) in large PAs. To test our hypothesis, PAH was induced by the combination of chronic hypoxia and an antiangiogenic compound (SU5416) treatment in mice. Static and sinusoidal pressure-inflation tests were performed on isolated conduit PAs at various frequencies (0.01–20 Hz) to obtain the mechanical properties in the absence of smooth muscle contraction. Static mechanical tests showed significant stiffening of large PAs with PAH, as expected. In dynamic mechanical tests, structural stiffness (κ) increased and damping ratio (D) decreased at a physiologically relevant frequency (10 Hz) in hypertensive PAs. The dynamic elastic modulus (E), a material stiffness, did not increase significantly with PAH. All dynamic mechanical properties were strong functions of frequency. In particular, κ, E and D increased with increasing frequency in control PAs. While this behavior remained for D in hypertensive PAs, it reversed for κ and E. Since these novel dynamic mechanical property changes were found in the absence of changes in smooth muscle cell content or contraction, changes in collagen and proteoglycans and their interactions are likely critical to arterial viscoelasticity in a way that has not been previously described. The impact of these changes in PA viscoelasticity on RV afterload in PAH awaits further investigation.
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MESH Headings
- Angiogenesis Inhibitors/adverse effects
- Animals
- Blood Pressure
- Chronic Disease
- Collagen/chemistry
- Elastic Modulus
- Familial Primary Pulmonary Hypertension
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/complications
- Hypertension, Pulmonary/pathology
- Hypoxia/complications
- Hypoxia/pathology
- Indoles/adverse effects
- Male
- Mice
- Mice, Inbred C57BL
- Myocytes, Smooth Muscle/chemistry
- Myocytes, Smooth Muscle/pathology
- Proteoglycans/chemistry
- Pyrroles/adverse effects
- Stress, Mechanical
- Vascular Stiffness
- Ventricular Dysfunction, Right/chemically induced
- Ventricular Dysfunction, Right/complications
- Ventricular Dysfunction, Right/pathology
- Viscosity
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Affiliation(s)
- Zhijie Wang
- Department of Biomedical Engineering, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
| | - Roderic S. Lakes
- Department of Biomedical Engineering, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
- Department of Engineering Physics, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
- Department of Material Science, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
| | - Mark Golob
- Department of Material Science, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
| | - Jens C. Eickhoff
- Department of Biostatistics and Medical Informatics, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
| | - Naomi C. Chesler
- Department of Biomedical Engineering, University of Wisconsin – Madison, Madison, Wisconsin, United States of America
- * E-mail:
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Menon A, Eddinger TJ, Wang H, Wendell DC, Toth JM, LaDisa JF. Altered hemodynamics, endothelial function, and protein expression occur with aortic coarctation and persist after repair. Am J Physiol Heart Circ Physiol 2012; 303:H1304-18. [PMID: 23023871 DOI: 10.1152/ajpheart.00420.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Coarctation of the aorta (CoA) is associated with substantial morbidity despite treatment. Mechanically induced structural and functional vascular changes are implicated; however, their relationship with smooth muscle (SM) phenotypic expression is not fully understood. Using a clinically representative rabbit model of CoA and correction, we quantified mechanical alterations from a 20-mmHg blood pressure (BP) gradient in the thoracic aorta and related the expression of key SM contractile and focal adhesion proteins with remodeling, relaxation, and stiffness. Systolic and mean BP were elevated for CoA rabbits compared with controls leading to remodeling, stiffening, an altered force response, and endothelial dysfunction both proximally and distally. The proximal changes persisted for corrected rabbits despite >12 wk of normal BP (~4 human years). Computational fluid dynamic simulations revealed reduced wall shear stress (WSS) proximally in CoA compared with control and corrected rabbits. Distally, WSS was markedly increased in CoA rabbits due to a stenotic velocity jet, which has persistent effects as WSS was significantly reduced in corrected rabbits. Immunohistochemistry revealed significantly increased nonmuscle myosin and reduced SM myosin heavy chain expression in the proximal arteries of CoA and corrected rabbits but no differences in SM α-actin, talin, or fibronectin. These findings indicate that CoA can cause alterations in the SM phenotype contributing to structural and functional changes in the proximal arteries that accompany the mechanical stimuli of elevated BP and altered WSS. Importantly, these changes are not reversed upon BP correction and may serve as markers of disease severity, which explains the persistent morbidity observed in CoA patients.
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Affiliation(s)
- Arjun Menon
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI, USA
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18
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Narayan J, Amatoury J, Cho JG, Verma M, Kairaitis K, Wheatley J, Amis T. Snoring effects on the baroreflex: an animal model. Respir Physiol Neurobiol 2012; 180:342-51. [PMID: 22244879 DOI: 10.1016/j.resp.2011.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
Abstract
Baroreflex sensitivity (BRS) is reduced in humans during snoring, however the mechanisms are unknown. We used an anaesthetised rabbit induced snoring (IS) model, to test: (1) whether IS was associated with reduced BRS; and (2) if snoring related vibration transmission to peri-carotid tissues influenced BRS levels. BRS was quantified using the spontaneous sequence technique. During IS, BRS fell by 40%, without any associated change in blood pressure (BP) but accompanied by an increase in heart rate (HR). Direct application of a snore frequency and intensity matched vibratory stimulus to the peri-carotid tissues of non-snoring tracheostomised rabbits had no effect on BRS, HR or BP. In conclusion, IS induced depression of BRS is likely mediated via a HR driven change in BRS operating point that is unrelated to snoring-related vibration transmission to carotid baroreceptors. The anaesthetised IS rabbit provides a model in which mechanistic interactions between snoring and BRS can be further explored.
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Affiliation(s)
- Jyotishna Narayan
- Ludwig Engel Centre for Respiratory Research, Sydney, NSW, Australia.
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19
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Lawrence AR, Gooch KJ. Differences in transmural pressure and axial loading ex vivo affect arterial remodeling and material properties. J Biomech Eng 2010; 131:101009. [PMID: 19831479 DOI: 10.1115/1.3200910] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Arterial axial strains, present in the in vivo environment, often become reduced due to either bypass grafting or the normal aging process. Since the prevalence of hypertension increases with aging, arteries are often exposed to both decreased axial stretch and increased transmural pressure. The combined effects of these mechanical stimuli on the mechanical properties of vessels have not previously been determined. Porcine carotid arteries were cultured for 9 days at normal and reduced axial stretch ratios in the presence of normotensive and hypertensive transmural pressures using ex vivo perfusion techniques. Measurements of the amount of axial stress were obtained through longitudinal tension tests while inflation-deflation test results were used to determine circumferential stresses and incremental moduli. Macroscopic changes in artery geometry and zero-stress state opening angles were measured. Arteries cultured ex vivo remodeled in response to the mechanical environment, resulting in changes in arterial dimensions of up to approximately 25% and changes in zero-stress opening angles of up to approximately 55 degrees . While pressure primarily affected circumferential remodeling and axial stretch primarily affected axial remodeling, there were clear examples of interactions between these mechanical stimuli. Culture with hypertensive pressure, especially when coupled with reduced axial loading, resulted in a rightward shift in the pressure-diameter relationship relative to arteries cultured with normotensive pressure. The observed differences in the pressure-diameter curves for cultured arteries were due to changes in artery geometry and, in some cases, changes in the arteries' intrinsic mechanical properties. Relative to freshly isolated arteries, arteries cultured under mechanical conditions similar to in vivo conditions were stiffer, suggesting that aspects of the ex vivo culture other than the mechanical environment also influenced changes in the arteries' mechanical properties. These results confirm the well-known importance of transmural pressure with regard to arterial wall mechanics while highlighting additional roles for axial stretch in determining mechanical behavior.
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Affiliation(s)
- Amanda R Lawrence
- Department of Bioengineering and Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, 19104, USA
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20
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Safar ME. Thirty-five years of clinical works on arterial stiffness and wave reflections in hypertension. Artery Res 2009. [DOI: 10.1016/j.artres.2009.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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21
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Guerrisi M, Vannucci I, Toschi N. Differential response of peripheral arterial compliance-related indices to a vasoconstrictive stimulus. Physiol Meas 2008; 30:81-100. [PMID: 19104136 DOI: 10.1088/0967-3334/30/1/006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Peripheral arterial elastic properties are greatly affected by cardiovascular as well as other pathologies, and their assessment can provide useful diagnostic indicators. The photoplethysmographic technique can provide finger blood volume and pressure waveforms non-invasively, which can then be processed statically or beat-to-beat to characterize parameters of the vessel wall mechanics. We employ an occlusion-deflation protocol in 48 healthy volunteers to study peripheral artery compliance-related indices over positive and negative transmural pressure values as well as under the influence of a valid vasoconstrictor (cigarette smoking). We calculate beat-to-beat indices (compliance index CI, distensibility index DI, three viscoelastic model parameters (compliance C, viscosity R and inertia L), pressure-volume loop areas A and damping factor DF as well as symmetrical (C(max)) and asymmetrical (C(A)(max)) static compliance estimates, and their distributions over transmural pressure. All distributions are bell-shaped and centred on negative transmural pressure values. Distribution heights were significantly lower in the smoking group (w.r.t. the non-smoking group) for C, CI, DI and significantly higher in R and DF. The estimated volume signal time lag was also significantly lower in the smoking group. Left and right distribution widths were significantly different in all parameters/groups but DI (both groups), C(A)(max), A (smoking group) and L (non-smoking group), and positions of maxima/minima were significantly altered in C(A)(max), R and DF. C, DF and CI are seen to be most sensitive under this protocol, while C(max) and C(A)(max) are seen to be insensitive. These quantities provide complementary, time- and transmural pressure-dependent information about arterial wall mechanics, and the choice of index should depend on the physiological conditions at hand as well as relevant time resolution and transmural pressure range.
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Affiliation(s)
- Maria Guerrisi
- Sezione di Fisica Medica, Facoltá di Medicina e Chirurgia, Università degli Studi di Roma Tor Vergata, Rome, Italy.
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Jagomägi K, Raamat R, Talts J, Ragun U, Länsimies E, Jurvelin J. Recording of dynamic arterial compliance changes during hand elevation. Clin Physiol Funct Imaging 2006; 25:350-6. [PMID: 16268987 DOI: 10.1111/j.1475-097x.2005.00636.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Finger arterial compliance has been studied on the beat-to-beat basis by using the digital arterial pressure and volume waveforms and performing measurements at zero transmural pressure during arm elevation in 11 volunteers. Continuous non-invasive finger blood pressure was measured by applying the Finapres monitor and the finger volume pulses were recorded by the UT9201 physiograph by using the photoplethysmographic principle of registration. Estimation of the beat-to-beat finger arterial compliance is based on (i) the recorded volume and pressure wave amplitudes (Vpulse and Ppulse) and (ii) on the calculation of the slope of the pressure-volume relationship from the first derivatives dV/dt and dP/dt of the recorded volume and pressure pulses near the point of the maximum slope. The results of the study demonstrate that the applied two methods similarly (correlation coefficient r = 0.97) describe the changes of the beat-to-beat compliance during hand elevation test. At the same time the second estimate was 18% higher than the first one (P = 0.003).
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Affiliation(s)
- Kersti Jagomägi
- Institute of Physiology, University of Tartu, Tartu, Estonia.
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23
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Safar ME, Laurent P. Pulse pressure and arterial stiffness in rats: comparison with humans. Am J Physiol Heart Circ Physiol 2003; 285:H1363-9. [PMID: 12969878 DOI: 10.1152/ajpheart.00513.2003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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24
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Mukai S, Gagnon M, Iloputaife I, Hamner JW, Lipsitz LA. Effect of systolic blood pressure and carotid stiffness on baroreflex gain in elderly subjects. J Gerontol A Biol Sci Med Sci 2003; 58:626-30. [PMID: 12865478 DOI: 10.1093/gerona/58.7.m626] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Aging is associated with diminished baroreflex sensitivity (gain), which predisposes elderly people to orthostatic hypotension, syncope, and cardiovascular morbidity. Aging is also associated with systolic blood pressure (SBP) elevation and carotid artery stiffness, which may both affect baroreflex gain. METHODS We examined the relation between SBP, carotid artery stiffness, and baroreflex gain in 34 healthy elderly (71 +/- 4 years) and 10 healthy young (31 +/- 3 years) subjects. SBP (Finapres) and carotid artery stiffness (ultrasound measures of relative carotid artery diameter changes during each blood pressure pulse) were measured. The gain of the transfer function relating the R-R interval to SBP fluctuations at a frequency of 0.05-0.15 Hz was used to assess cardiovagal baroreflex gain. RESULTS Elderly subjects had higher carotid artery stiffness (14.2 +/- 5.1 vs 6.6 +/- 1.8, p <.05), higher SBP (146 +/- 24 vs 125 +/- 8 mmHg, p =.012), and lower baroreflex gain (8.2 +/- 6.4 vs 16.3 +/- 7.4, p <.05) than young subjects. Among all subjects, SBP and carotid artery stiffness both correlated with baroreflex gain (r = -.39, p =.02 for both). Although SBP was related to stiffness across all subjects, this relation was not present among the elderly subjects. Within the elderly group, only SBP was independently related to baroreflex gain (R(2) =.51, p =.009). CONCLUSIONS SBP elevation in elderly people may affect the neural or cardiac response to blood pressure fluctuations, independent of the mechanical properties of barosensory regions in the carotid artery. Future studies should examine the effect of pharmacologic treatment of hypertension on baroreflex gain in elderly people.
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Affiliation(s)
- Seiji Mukai
- Research and Training Institute, Hebrew Rehabilitation Center for Aged, Gerontology Division, Beth Israel Deaconess Medical Center, and Division on Aging, Harvard Medical School, Boston, Massachusetts 02131, USA
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van Dijk RA, Dekker JM, Nijpels G, Heine RJ, Bouter LM, Stehouwer CD. Brachial artery pulse pressure and common carotid artery diameter: mutually independent associations with mortality in subjects with a recent history of impaired glucose tolerance. Eur J Clin Invest 2001; 31:756-63. [PMID: 11589717 DOI: 10.1046/j.1365-2362.2001.00884.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Decreased large artery function, as reflected by increased brachial artery pulse pressure and increased carotid artery diameter and stiffness, may contribute to the increased mortality risk that is observed in subjects with impaired glucose tolerance. We therefore investigated the association between brachial artery pulse pressure and carotid artery diameter and stiffness, which are estimates of central artery stiffness and arterial remodelling, respectively, and mortality in subjects with a recent history of impaired glucose tolerance. DESIGN A prospective, population-based cohort study. We measured brachial artery pulse pressure by oscillometric blood pressure measurements, and common carotid artery diameter and distensibility and compliance coefficients by ultrasound in 140 subjects with a recent history of impaired glucose tolerance. During a median 6.6-year follow-up, 16 subjects died. RESULTS Brachial artery pulse pressure and common carotid artery diameter were positively related to all-cause mortality [hazard ratios per standard deviation, 1.7 (1.2-2.5) and 2.1 (1.3-3.3), respectively]. Results were similar after adjustment for gender, age, waist-to-hip ratio, body mass index, total cholesterol concentration, pre-existent cardiovascular disease, and hypertension, and after additional mutual adjustment. Common carotid artery distensibility and compliance coefficients were not statistically significantly associated with mortality. CONCLUSIONS Among subjects with a recent history of impaired glucose tolerance, brachial artery pulse pressure and common carotid artery diameter are independently associated with mortality risk. Stiffness of the central arteries may explain the association between pulse pressure and mortality risk. The association between carotid diameter and mortality risk is more likely to reflect arterial remodelling in response to atherosclerosis than that in response to increased local stiffness.
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Affiliation(s)
- R A van Dijk
- Institute for Cardiovascular Research Vrije Universiteit and Department of Internal Medicine, University Hospital Vrije Universiteit, Amsterdam, the Netherlands.
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Spencer EB, Sheafor DH, Hertzberg BS, Bowie JD, Nelson RC, Carroll BA, Kliewer MA. Nonstenotic internal carotid arteries: effects of age and blood pressure at the time of scanning on Doppler US velocity measurements. Radiology 2001; 220:174-8. [PMID: 11425992 DOI: 10.1148/radiology.220.1.r01jl33174] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To assess the effects of age and blood pressure at the time of scanning on internal carotid artery velocities and cross-sectional diameter at Doppler ultrasonography (US). MATERIALS AND METHODS During 12 months, 1,020 consecutive patients underwent internal carotid artery Doppler US. No or minimal arterial disease was found in 142 patients (67 women, 75 men). Blood pressure was recorded prior to examination. The angle-corrected internal carotid artery peak systolic and end-diastolic velocities were obtained. The effects of systolic blood pressure, diastolic blood pressure, pulse pressure, age, chronic hypertension, and medications for hypertension on velocities were evaluated by using linear regression analysis. RESULTS Peak systolic velocity was influenced by age (P =.008), systolic blood pressure (P =.009), diastolic blood pressure (P =.003), and pulse pressure (P =.017) but not history of hypertension (P =.53) or antihypertensive medication use (P =.77). Increasing age decreased peak systolic velocity by 0.34 cm/sec/y. End-diastolic velocity was influenced by age (P <.001) but not by systolic, diastolic, or pulse pressure (all P values were >.13). CONCLUSION Internal carotid artery peak systolic velocities decrease with advancing age and increase with increasing pulse pressure. The effects of blood pressure at the time of scanning are small, but isolated systolic hypertension could cause increases in spurious velocity.
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Affiliation(s)
- E B Spencer
- Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710, USA
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Blondel WC, Didelon J, Maurice G, Carteaux JP, Wang X, Stoltz JF. Investigation of 3-D mechanical properties of blood vessels using a new in vitro tests system: results on sheep common carotid arteries. IEEE Trans Biomed Eng 2001; 48:442-51. [PMID: 11322532 DOI: 10.1109/10.915710] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In order to investigate the three-dimensional (3-D) mechanical properties of blood vessels, a new experimental device is described allowing in vitro static and dynamic measurements on segments of arteries with high technical performances. Static tests are applied to sheep common carotid arteries. Considering a thick-walled cylindrical model of orthotropic material under large deformations, a classical 3-D approach based on strain energy density is used to calculate the resulting mechanical behavior law in radial and circumferencial directions and stresses distribution throughout the wall thickness. Results are presented with reference to unloaded and zero-stress initial state thanks to simple measurements of inner and outer circumferences. A particular ratio relating the two main stresses (circumferential and longitudinal) is calculated that put into the forth the progressive modifications in the direction of the predominant stress in the wall and the specific radial location where these changes occur. We observe that this point location is a function of the test conditions of the specimen, i.e., stretching length and level of pressure.
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Affiliation(s)
- W C Blondel
- Department, UMR CNRS 7563 and IFR CNRS W0070, Faculté de médecine, Vandoeuvre-lés-Nancy, France.
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van Dijk RA, Nijpels G, Twisk JW, Steyn M, Dekker JM, Heine RJ, Donker AJ, Stehouwer CD. Change in common carotid artery diameter, distensibility and compliance in subjects with a recent history of impaired glucose tolerance: a 3-year follow-up study. J Hypertens 2000; 18:293-300. [PMID: 10726716 DOI: 10.1097/00004872-200018030-00009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To assess the development of common carotid artery properties (diameter, distensibility and compliance) in a cohort of 140 subjects (mean age 65.8 years, SD 7.5 years) originally diagnosed as impaired glucose tolerant in a population-based study, and to explore determinants of changes observed. DESIGN An observational, longitudinal study over a 3-year-period. METHODS Vessel wall movement detector system based on ultrasonography, linear generalized estimating equations. RESULTS Carotid artery diameter rose from 6.87-7.02 mm (+ 2.2%, P<0.001). Distensibility decreased from 11.8 to 10.9 x 10-3 kPa-1 (-8.3%, P=0.009). Compliance decreased from 0.44-043 mm2 kPa-1 (P=0.17). Changes in blood pressure level were negatively associated with changes in distensibility and compliance. Baseline fasting glucose levels were positively associated with changes in diameter, while fasting insulin levels were negatively associated with changes in distensibility and compliance in men, but not in women. CONCLUSIONS In subjects with a recent history of impaired glucose tolerance, we observed an increase in carotid artery diameter and a decrease in distensibility. Change in blood pressure level and baseline fasting glucose and HbA1c levels were positively related to the increase in diameter. In men, but not in women, baseline fasting insulin levels were associated with an acceleration of these changes.
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Affiliation(s)
- R A van Dijk
- Institute for Cardiovascular Research Vrije Universiteit and Department of Internal Medicine, University Hospital Vrije Universiteit, Amsterdam, The Netherlands
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