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Thorn CE, Gates PE, Casanova F, Ramalli A, Tortoli P, Palombo C, Shore AC, Aizawa K. Interaction of macro- and microvascular function underlies brachial artery flow-mediated dilation in humans. Am J Physiol Heart Circ Physiol 2024; 327:H268-H274. [PMID: 38787380 DOI: 10.1152/ajpheart.00158.2024] [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: 04/10/2024] [Revised: 05/21/2024] [Accepted: 05/21/2024] [Indexed: 05/25/2024]
Abstract
Brachial artery flow-mediated dilation (BAFMD) is induced by hyperemic wall shear rate (WSR) following forearm ischemia. In older adults, there appears to be a reduced brachial hyperemic WSR and altered stimulus-response relationship compared with young adults. However, it is unclear if an altered forearm microvascular response to ischemia influences brachial hyperemic WSR in older adults. We determined associations between brachial hyperemic WSR and forearm skeletal muscle oxygen saturation in young and older adults. Healthy young (n = 17, 29 ± 7 yr) and older (n = 32, 65 ± 4 yr) adults participated in the study. BAFMD by a multigate spectral Doppler system and forearm skeletal muscle oxygen saturation by near-infrared spectroscopy were concurrently measured. When compared with the young, older adults showed reduced oxygen extraction kinetics (OE, 0.15 [0.12-0.17] vs. 0.09 [0.05-0.12]%s-1) and magnitude (So2deficit, 3,810 ± 1,420 vs. 2,723 ± 1,240%s) during ischemia, as well as oxygen resaturation kinetics (So2slope, 2.5 ± 0.7 vs. 1.7 ± 0.7%s-1) upon reperfusion (all P < 0.05). When OE in the young and So2slope in older adults were stratified by their median values, young adults with OE above the median had greater hyperemic WSR parameters compared with those below the median (P < 0.05), but So2slope in older adults did not show clear differences in hyperemic WSR parameters between those above/below the median. This study demonstrates that, in addition to a reduced microvascular response to ischemia, there may be a dissociation between microvascular response to ischemia and brachial hyperemic WSR in older adults, which may result in a further impairment of BAFMD in this cohort.NEW & NOTEWORTHY Microvascular response to ischemia and subsequent reperfusion is diminished in older adults compared with the young. Furthermore, there appears to be a dissociation between the microvascular response to ischemia and brachial hyperemic WSR in older adults, which may further disturb the BAFMD process in this cohort. A reduced BAFMD in older adults may be a result of multiple alterations occurring both at macro- and microcirculation.
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Affiliation(s)
- Clare E Thorn
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- National Institute of Health and Care Research Exeter Clinical Research Facility, Exeter, United Kingdom
- Department of Health and Care Professions, Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Phillip E Gates
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- National Institute of Health and Care Research Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Francesco Casanova
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- National Institute of Health and Care Research Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Alessandro Ramalli
- Department of Information Engineering, University of Florence, Florence, Italy
| | - Piero Tortoli
- Department of Information Engineering, University of Florence, Florence, Italy
| | - Carlo Palombo
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Angela C Shore
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- National Institute of Health and Care Research Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Kunihiko Aizawa
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- National Institute of Health and Care Research Exeter Clinical Research Facility, Exeter, United Kingdom
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Millinger J, Langenskiöld M, Nygren A, Österberg K, Nordanstig J. Arterial Blood Flow and Effects on Limb Tissue Perfusion During Endoshunting of the Common Iliac Artery in an Experimental Porcine Model. EJVES Vasc Forum 2024; 61:54-61. [PMID: 38375024 PMCID: PMC10875111 DOI: 10.1016/j.ejvsvf.2024.01.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/10/2023] [Accepted: 01/22/2024] [Indexed: 02/21/2024] Open
Abstract
Objective Temporary arterial shunting is an established method to prevent tissue ischaemia. Although less well established, shunting might also be achieved through endovascular and hybrid techniques, known as endoshunting. Endoshunting offers advantages, for example, enabling minimally invasive access and avoiding complete occlusion of the donor artery. In an ex vivo bench test, volume flow in various interconnected endoshunt systems has been tested previously. This study aimed to investigate the capacity of the best performing endoshunt system in vivo. Methods Six anaesthetised pigs had their common iliac arteries (CIAs) explored, with the left CIA serving as the experimental and the right CIA as the control. Mean arterial pressure, regional blood flow, endoshunt flow, and regional oxygen extraction and lactate production were recorded. Distal muscle perfusion was monitored using near infrared spectroscopy (NIRS). Each experiment involved baseline registration, cross clamping of the left CIA, a 120 minute endoshunt session, and restoration of native flow. Results During cross clamping, NIRS values on the experimental side reached the lowest measurable value. Following endoshunt activation, there were no NIRS value differences between the experimental and control extremities whereas the average arterial flow decreased in both the experimental (270-140 mL/min, p = .028) and control extremities (245-190 mL/min, p = .25), with a greater drop on the endoshunted side (48% vs. 22%, respectively). Lactate levels temporarily increased by 42% in the endoshunted limb on endoshunt activation but were normalised within an hour. Oxygen extraction remained constant at 55% on the control side but increased to 70% on the endoshunted side (p = .068). Conclusion In this animal model, a flow optimised endoshunt system appeared to provide sufficient blood flow and restored stable tissue perfusion. Although arterial flow was slightly lower and oxygen extraction slightly higher on the endoshunted side, the endoshunt seemed to deliver adequate perfusion to prevent significant ischaemia.
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Affiliation(s)
- Johan Millinger
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Vascular Surgery, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Marcus Langenskiöld
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Vascular Surgery, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Andreas Nygren
- Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Anaesthesiology and Intensive Care Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Klas Österberg
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Joakim Nordanstig
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Vascular Surgery, Sahlgrenska University Hospital, Gothenburg, Sweden
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Trigger Points and Contracture/Contraction Knots: What’s in a Name? Reply to Dommerholt, J.; Gerwin, R.D. Contracture Knots vs. Trigger Points. Comment on “Ball et al. Ultrasound Confirmation of the Multiple Loci Hypothesis of the Myofascial Trigger Point and the Diagnostic Importance of Specificity in the Elicitation of the Local Twitch Response. Diagnostics 2022, 12, 321”. Diagnostics (Basel) 2022; 12:diagnostics12102366. [DOI: 10.3390/diagnostics12102366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
We are responding to the comment by Dommerholt and Gerwin that we have reverse-defined “myofascial trigger point” (MTrP) and “contracture/contraction knot.” In attempting to maintain philosophical agreement with specific and implied aspects of their integrated hypothesis of trigger-point formation (namely a MTrP being ischemic and hypoxic), we referred to the MTrP as the small hyperechoic signal rather than the larger hypoechoic (and therefore hyperperfused) structure surrounding it. It was never our intent to re-define nor contribute to confusion. In making this concession with respect to Dommerholt and Gerwin’s preferred nomenclature, however, we must instead now reconcile what we image as a hypoechoic (and therefore hyperperfused) MTrP with it being concurrently hypoxic.
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Fredriksson I, Larsson M, Strömberg T, Iredahl F. Vasomotion analysis of speed resolved perfusion, oxygen saturation, red blood cell tissue fraction, and vessel diameter: Novel microvascular perspectives. Skin Res Technol 2021; 28:142-152. [PMID: 34758168 PMCID: PMC9907591 DOI: 10.1111/srt.13106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 08/21/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Vasomotion is the spontaneous oscillation in vascular tone in the microcirculation and is believed to be a physiological mechanism facilitating the transport of blood gases and nutrients to and from tissues. So far, Laser Doppler flowmetry has constituted the gold standard for in vivo vasomotion analysis. MATERIALS AND METHODS We applied vasomotion analysis to speed-resolved perfusion, oxygen saturation, red blood cell tissue (RBC) tissue fraction, and average vessel diameter from five healthy individuals at rest measured by the newly developed Periflux 6000 EPOS system over 10 minutes. Magnitude scalogram and the time-averaged wavelet spectra were divided into frequency intervals reflecting endothelial, neurogenic, myogenic, respiratory, and cardiac function. RESULTS Recurrent high-intensity periods of the myogenic, neurogenic, and endothelial frequency intervals were found. The neurogenic activity was considerably more pronounced for the oxygen saturation, RBC tissue fraction, and vessel diameter signals, than for the perfusion signals. In a correlation analysis we found that changes in perfusion in the myogenic, neurogenic, and endothelial frequency intervals precede changes in the other signals. Furthermore, changes in average vessel diameter were in general negatively correlated to the other signals in the same frequency intervals, indicating the importance of capillary recruitment. CONCLUSION We conclude that vasomotion can be observed in signals reflecting speed resolved perfusion, oxygen saturation, RBC tissue fraction, and vessel diameter. The new parameters enable new aspects of the microcirculation to be observed.
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Affiliation(s)
- Ingemar Fredriksson
- Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - Marcus Larsson
- Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - Tomas Strömberg
- Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - Fredrik Iredahl
- Department of Health, Medicine and Caring Sciences, Linköping University, Division of Community Medicine, Linköping, Sweden.,Department of Primary health care, Region Östergötland, Linköping, Sweden
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Meertens R, Knapp KM, Strain WD, Casanova F, Ball S, Fulford J, Thorn C. In vivo Measurement of Intraosseous Vascular Haemodynamic Markers in Human Bone Tissue Utilising Near Infrared Spectroscopy. Front Physiol 2021; 12:738239. [PMID: 34630158 PMCID: PMC8497693 DOI: 10.3389/fphys.2021.738239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/25/2021] [Indexed: 11/13/2022] Open
Abstract
Objective: Poor vascular health is associated with reduced bone strength and increased risk of fragility fracture. However, direct measurement of intraosseous vascular health is difficult due to the density and mineral content of bone. We investigated the feasibility of using a commercially available continuous wave near infrared spectroscopy (NIRS) system for the investigation of vascular haemodynamics in human bone in vivo. Approach: An arterial occlusion (AO) protocol was developed for obtaining haemodynamic measurements of the proximal tibia and lateral calf, including assessment of the protocol’s intra operator reproducibility. For 36 participants, intraosseous haemodynamics derived by NIRS were compared to alternative tests of bone health based on dual x-ray absorptiometry (DXA) testing and MRI. Main Results: Near infrared spectroscopy markers of haemodynamics of the proximal tibia demonstrated acceptable reproducibility, comparable with reproducibility assessments of alternative modalities measuring intraosseous haemodynamics, and the use of NIRS for measuring muscle. Novel associations have been demonstrated between haemodynamic markers of bone measured with NIRS and body composition and bone mineral density (BMD) measurements obtained with both DXA and MRI. Significance: Near infrared spectroscopy provides inexpensive, non-invasive, safe, and real time data on changes in oxygenated and deoxygenated haemoglobin concentration in bone at the proximal tibia. This study has demonstrated the potential for NIRS to contribute to research investigating the pathophysiological role of vascular dysfunction within bone tissue, but also the limitations and need for further development of NIRS technology.
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Affiliation(s)
- Robert Meertens
- College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Karen M Knapp
- College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | | | - Francesco Casanova
- College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Susan Ball
- NIHR Applied Research Collaboration South West Peninsula (PenARC), College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Jon Fulford
- NIHR Exeter Clinical Research Facility, College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Clare Thorn
- College of Medicine and Health, University of Exeter, Exeter, United Kingdom
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Davies T, Gilbert-Kawai E, Wythe S, Meale P, Mythen M, Levett D, Mitchell K, Grocott M, Clough G, Martin D. Sustained vasomotor control of skin microcirculation in Sherpas versus altitude-naive lowlanders: Experimental evidence from Xtreme Everest 2. Exp Physiol 2018; 103:1494-1504. [PMID: 30182473 DOI: 10.1113/ep087236] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 08/21/2018] [Indexed: 12/20/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do Sherpa highlanders, when exposed to graded hypobaric hypoxia, exhibit enhanced vasomotor and neurovascular control to maintain microcirculatory flux, and thus tissue oxygenation, when compared with altitude-naive lowlanders? What is the main finding and its importance? Sherpas, when exposed to hypobaric hypoxia at high altitude, demonstrated superior preservation of their peripheral microcirculatory perfusion, a greater oxygen unloading rate and sustained microvascular reactivity with enhanced vasomotion, when compared with altitude-naive lowlanders. These differences have not been reported previously and may improve our understanding of the multifactorial responses to sustained environmental hypoxia. ABSTRACT Enhanced oxygen delivery, consequent to an increased microvascular perfusion, has been postulated to play a key role in the physiological adaptation of Tibetan highlanders to the hypobaric hypoxia encountered at high altitude. We tested the hypothesis that Sherpas, when exposed to graded hypobaric hypoxia, demonstrate enhanced vasomotor and neurovascular control to maintain microcirculatory flux, and thus tissue oxygenation, when compared with altitude-naive lowlanders. Eighty-three lowlanders [39 men and 44 women, 38.8 (13.1) years old; mean (SD)] and 61 Sherpas [28 men and 33 women, 27.9 (6.9) years old] were studied on ascent to Everest Base Camp over 11 days. Skin blood flux and tissue oxygen saturation were measured simultaneously using combined laser Doppler fluximetry and white light spectroscopy at baseline, 3500 and 5300 m. In both cohorts, ascent resulted in a decline in the sympathetically mediated microvascular constrictor response (P < 0.001), which was more marked in lowlanders than in Sherpas (P < 0.001). The microvascular dilator response evaluated by postocclusive reactive hyperaemia was significantly greater in Sherpas than in lowlanders at all sites (P < 0.002). Spectral analysis of the blood flux signals revealed enhanced myogenic (vasomotion) activity in Sherpas, which was unaffected by ascent to 5300 m. Although skin tissue oxygenation was lower in Sherpas than in lowlanders, the oxygen unloading rate was faster, and deoxyhaemoglobin levels higher, at all altitudes. Together, these data suggest that Sherpas, when exposed to hypobaric hypoxia, demonstrated superior preservation of peripheral microcirculatory perfusion compared with altitude-naive lowlanders. The physiological differences in local microvasculature vasomotor and neurovascular control may play a key role in Sherpa adaptation to high-altitude hypobaric hypoxia by sustaining local perfusion and tissue oxygenation.
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Affiliation(s)
- Thomas Davies
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
| | - Edward Gilbert-Kawai
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
| | - Stephen Wythe
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
| | - Paula Meale
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
| | - Monty Mythen
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
| | - Denny Levett
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK.,Faculty of Medicine (CES) and Institute for Life Science, University of Southampton, Southampton, UK.,NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK.,Centre for Human Integrative Physiology, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Kay Mitchell
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
| | - Michael Grocott
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK.,Faculty of Medicine (CES) and Institute for Life Science, University of Southampton, Southampton, UK.,NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK.,Centre for Human Integrative Physiology, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Geraldine Clough
- Institute of Developmental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Daniel Martin
- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK.,Critical Care Unit, Royal Free Hospital, London, UK
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- University College London Centre for Altitude Space and Extreme Environment Medicine, UCLH NIHR Biomedical Research Centre, Institute of Sport and Exercise Health, London, UK
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Kuliga KZ, Gush R, Clough GF, Chipperfield AJ. Time-dependent Behavior of Microvascular Blood Flow and Oxygenation: a Predictor of Functional Outcomes. IEEE Trans Biomed Eng 2017; 65:1049-1056. [DOI: 10.1109/tbme.2017.2737328] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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