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O'Brien MW, Shivgulam ME. Mechanistic, participant, and movement-related factors that contribute to low-flow-mediated constriction. Eur J Appl Physiol 2023; 123:2687-2697. [PMID: 37804365 DOI: 10.1007/s00421-023-05332-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 09/21/2023] [Indexed: 10/09/2023]
Abstract
Endothelial function is commonly determined via the ultrasound-based flow-mediated dilation (FMD) technique which assesses arterial dilation in response to a hyperemia response following distal cuff occlusion. However, the low-flow-mediated constriction (L-FMC) response during cuff-induced ischemia is often overlooked. L-FMC provides unique information regarding endothelial function, but vascular researchers may be unclear on what this metric adds. Therefore, the objective of this review was to examine the mechanistic determinants and participant-level factors of L-FMC. Existing mechanistic studies have demonstrated that vasoreactivity to low flow may be mediated via non-nitric oxide vasodilators (i.e., endothelial hyperpolarizing factors and/or prostaglandins), inflammatory markers, and enhancement of vasoconstriction via endothelin-1. In general, participant-level factors such as aging and presence of cardiovascular conditions generally are associated with attenuated L-FMC responses. However, the influence of sex on L-FMC is unclear with divergent results between L-FMC in upper versus lower limb vessels. The ability of aerobic exercise to augment L-FMC (i.e., make more negative) is well supported, but there is a major gap in the literature concerning the mechanistic underpinnings of this observation. This review summarizes that while larger L-FMC responses are generally healthy, the impact of interventions to augment/attenuate L-FMC has not included mechanistic measures that would provide insight into non-nitric oxide-based endothelial function. Clarifications to terminology and areas of further inquiry as it relates to the specific pharmacological, individual-level factors, and lifestyle behaviors that impact L-FMC are highlighted. A greater integration of mechanistic work alongside applied lifestyle interventions is required to better understand endothelial cell function to reductions in local blood flow.
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Affiliation(s)
- Myles W O'Brien
- School of Physiotherapy (Faculty of Health) and Department of Medicine (Faculty of Medicine, Dalhousie University, Halifax, NS, Canada.
- Geriatric Medicine Research, Dalhousie University & Nova Scotia Health, Halifax, NS, B3H 4R2, Canada.
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2
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Marchena-Romero KJ, Ji X, Sommer R, Centen A, Ramirez J, Poulin JM, Mikulis D, Thrippleton M, Wardlaw J, Lim A, Black SE, MacIntosh BJ. Examining temporal features of BOLD-based cerebrovascular reactivity in clinical populations. Front Neurol 2023; 14:1199805. [PMID: 37396759 PMCID: PMC10310960 DOI: 10.3389/fneur.2023.1199805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/25/2023] [Indexed: 07/04/2023] Open
Abstract
Background Conventional cerebrovascular reactivity (CVR) estimation has demonstrated that many brain diseases and/or conditions are associated with altered CVR. Despite the clinical potential of CVR, characterization of temporal features of a CVR challenge remains uncommon. This work is motivated by the need to develop CVR parameters that characterize individual temporal features of a CVR challenge. Methods Data were collected from 54 adults and recruited based on these criteria: (1) Alzheimer's disease diagnosis or subcortical Vascular Cognitive Impairment, (2) sleep apnea, and (3) subjective cognitive impairment concerns. We investigated signal changes in blood oxygenation level dependent (BOLD) contrast images with respect to hypercapnic and normocapnic CVR transition periods during a gas manipulation paradigm. We developed a model-free, non-parametric CVR metric after considering a range of responses through simulations to characterize BOLD signal changes that occur when transitioning from normocapnia to hypercapnia. The non-parametric CVR measure was used to examine regional differences across the insula, hippocampus, thalamus, and centrum semiovale. We also examined the BOLD signal transition from hypercapnia back to normocapnia. Results We found a linear association between isolated temporal features of successive CO2 challenges. Our study concluded that the transition rate from hypercapnia to normocapnia was significantly associated with the second CVR response across all regions of interest (p < 0.001), and this association was highest in the hippocampus (R2 = 0.57, p < 0.0125). Conclusion This study demonstrates that it is feasible to examine individual responses associated with normocapnic and hypercapnic transition periods of a BOLD-based CVR experiment. Studying these features can provide insight on between-subject differences in CVR.
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Affiliation(s)
- Kayley-Jasmin Marchena-Romero
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Xiang Ji
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - Rosa Sommer
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Andrew Centen
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Joel Ramirez
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - Joshua M. Poulin
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - David Mikulis
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Division of Neuroradiology, Joint Department of Medical Imaging, University Health Network, Toronto, ON, Canada
- Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
| | - Michael Thrippleton
- Brain Research Imaging Centre, Centre for Clinical Brain Sciences, UK Dementia Research Institute Centre, The University of Edinburgh, Edinburgh, United Kingdom
| | - Joanna Wardlaw
- Brain Research Imaging Centre, Centre for Clinical Brain Sciences, UK Dementia Research Institute Centre, The University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew Lim
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Sandra E. Black
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
| | - Bradley J. MacIntosh
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
- Dr. Sandra Black Centre for Brain Resilience and Recovery, Toronto, ON, Canada
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Elyas S, Adingupu D, Aizawa K, Casanova F, Gooding K, Fulford J, Mawson D, Gates PE, Shore AC, Strain D. Cerebral small vessel disease, systemic vascular characteristics and potential therapeutic targets. Aging (Albany NY) 2021; 13:22030-22039. [PMID: 34550097 PMCID: PMC8507297 DOI: 10.18632/aging.203557] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 08/31/2021] [Indexed: 12/05/2022]
Abstract
Introduction: Cerebral small vessel disease (SVD) is prevalent in the elderly population and is associated with increased risk of dementia, stroke and disability. Currently there are no clear targets or strategies for the treatment of cerebral SVD. We set out to identify modifiable vascular treatment targets. Patients and Methods: 112 participants with and without a history of CVD underwent macrovascular, microvascular and endothelial function tests and an MRI head scan. Results: Increased carotid intima media thickness and carotid-femoral pulse wave velocity were associated with cerebral WMH (β=1·1 p=0·001 and β=1·66, p<0·0001 respectively). Adjusted cerebral resistance index (p=0·03) and brachial flow mediated dilation time to peak (p=0·001) were associated with the severity of cerebral WMH independent of age and sex. Post occlusive reactive hyperaemia time as a measure of microvascular reactivity was associated with WMH after adjustment for age and sex (p=0·03). Ankle Brachial Pressure Index and urinary albumin excretion rate predicted the severity of cerebral WMH (p=0·02 and 0·01 respectively). Age and hypertension were the most important risk factors for WMH severity (p< 0·0001). Discussion: In addition to hypertension, microalbuminuria, arterial stiffness, vascular reactivity and cerebrovascular resistance could be potential treatment targets to halt the development or progression of cerebral SVD.
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Affiliation(s)
- Salim Elyas
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK.,Academic Department of Healthcare for Older People, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Damilola Adingupu
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Kunihiko Aizawa
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Francesco Casanova
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Kim Gooding
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Jonathan Fulford
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Dave Mawson
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Phillip E Gates
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - Angela C Shore
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK
| | - David Strain
- Institute of Biomedical and Clinical Science and NIHR Exeter Clinical Research Facility, University of Exeter Medical School, Exeter EX2 5AX, UK.,Academic Department of Healthcare for Older People, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK
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4
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Shenouda N, Ramick MG, Lennon SL, Farquhar WB, Edwards DG. High dietary sodium augments vascular tone and attenuates low-flow mediated constriction in salt-resistant adults. Eur J Appl Physiol 2020; 120:1383-1389. [PMID: 32306153 DOI: 10.1007/s00421-020-04370-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 04/05/2020] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Low-flow mediated constriction (L-FMC) has emerged as a valuable and complementary measure of flow-mediated dilation (FMD) for assessing endothelial function non-invasively. High dietary sodium has been shown to impair FMD independent of changes in blood pressure (BP), but its effects on L-FMC are unknown. PURPOSE To test the hypothesis that high dietary sodium would attenuate brachial artery L-FMC in salt-resistant adults. METHODS Fifteen healthy, normotensive adults (29 ± 6 years) participated in a controlled feeding study. Following a run-in diet, participants completed a 7-day low sodium (LS; 20 mmol sodium/day) and 7-day high sodium (HS; 300 mmol sodium/day) diet in randomized order. On the last day of each diet, 24 h urine was collected and assessments of 24 h ambulatory BP and L-FMC were performed. Salt-resistance was defined as a change in 24 h ambulatory mean arterial pressure (MAP) between the LS and HS diets of ≤ 5 mmHg. Resting vascular tone and L-FMC were calculated from ultrasound-derived arterial diameters. RESULTS High dietary sodium increased serum sodium and urinary sodium excretion (p < 0.001 for both), but 24 h MAP was unchanged (p = 0.16) by design. High dietary sodium augmented vascular tone (LS: 91 ± 23%, HS: 125 ± 56%, p = 0.01) and attenuated L-FMC (LS: - 0.58 ± 0.99%, HS: 0.17 ± 1.23%, p = 0.008). CONCLUSION These findings in salt-resistant adults provide additional evidence that dietary sodium has adverse vascular effects independent of changes in BP.
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Affiliation(s)
- Ninette Shenouda
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA
| | - Meghan G Ramick
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA.,Department of Kinesiology, West Chester University, West Chester, PA, USA
| | - Shannon L Lennon
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA
| | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA
| | - David G Edwards
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA.
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Aizawa K, Ramalli A, Sbragi S, Tortoli P, Casanova F, Morizzo C, Thorn CE, Shore AC, Gates PE, Palombo C. Arterial wall shear rate response to reactive hyperaemia is markedly different between young and older humans. J Physiol 2019; 597:4151-4163. [PMID: 31245837 DOI: 10.1113/jp278310] [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: 05/15/2019] [Accepted: 06/24/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The vasodilatory response to reactive hyperaemia is impaired with advancing age, but it is unclear whether this is because of an altered wall shear rate (WSR) stimulus or an altered flow-mediated dilatation (FMD) response. Using new technology that allows detailed WSR measurement, we assessed the WSR-FMD response in healthy older people. Our data show that older people have a markedly altered and diminished WSR response to reactive hyperaemia compared to young people, but reduced WSR alone does not fully explain reduced FMD. In young people, WSR appears to be coupled to FMD but, by age ∼65 years, the arterial vasodilatory response has begun to uncouple from the WSR stimulus. These findings point to the importance and utility of comprehensively characterizing the WSR-FMD response when using reactive hyperaemia to assess vascular function, as well as giving new insight into the age-related alteration in vascular function. ABSTRACT The vasodilatory response to reactive hyperaemia is impaired with age, but it is unknown whether this is because of an altered wall shear rate (WSR) stimulus or an altered flow-mediated dilatation (FMD) response to the WSR stimulus. Inherent difficulties in measuring blood flow velocity close to the arterial wall have prevented detailed assessment of the WSR-FMD response. Using an enhanced multigate spectral Doppler ultrasound system (ultrasound advanced open platform), we aimed to produce new data on the WSR-FMD relationship in healthy older adults. Sixty healthy people, comprising 28 young (27.5 ± 5.5 years) and 32 older (64.9 ± 3.7 years) individuals, underwent FMD assessment. Raw data were post-processed using custom-designed software to obtain WSR and diameter parameters. The data revealed that older people have a much altered and diminished WSR response to reactive hyperaemia compared to younger people [e.g. WSR peak: 622 (571-673) vs. 443 (396-491) 1/s in young and older respectively; P < 0.05]. However, reduced WSR alone does not appear to fully explain the reduced FMD response in older people because associations between WSR and FMD were few and weak. This was in contrast to young adults, where associations were strong. We conclude that WSR during FMD is much altered and diminished in older people, and there appears to be an 'uncoupling' of WSR from FMD in older people that may reflect a loss of precision in the reactive hyperaemia stimulus-response relationship. These findings also point to the importance and utility of comprehensively characterizing the WSR-FMD response when using reactive hyperaemia to assess vascular function.
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Affiliation(s)
- Kunihiko Aizawa
- Diabetes and Vascular Medicine Research Centre, NIHR Exeter Clinical Research Facility, University of Exeter College of Medicine and Health, Exeter, UK
| | - Alessandro Ramalli
- Department of Information Engineering, University of Florence, Florence, Italy.,Laboratory of Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Sara Sbragi
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Piero Tortoli
- Department of Information Engineering, University of Florence, Florence, Italy
| | - Francesco Casanova
- Diabetes and Vascular Medicine Research Centre, NIHR Exeter Clinical Research Facility, University of Exeter College of Medicine and Health, Exeter, UK
| | - Carmela Morizzo
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
| | - Clare E Thorn
- Diabetes and Vascular Medicine Research Centre, NIHR Exeter Clinical Research Facility, University of Exeter College of Medicine and Health, Exeter, UK
| | - Angela C Shore
- Diabetes and Vascular Medicine Research Centre, NIHR Exeter Clinical Research Facility, University of Exeter College of Medicine and Health, Exeter, UK
| | - Phillip E Gates
- Diabetes and Vascular Medicine Research Centre, NIHR Exeter Clinical Research Facility, University of Exeter College of Medicine and Health, Exeter, UK
| | - Carlo Palombo
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy
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6
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Kranen SH, Bond B, Williams CA, Barker AR. Reliability of low-flow vasoreactivity in the brachial artery of adolescents. JOURNAL OF CLINICAL ULTRASOUND : JCU 2019; 47:133-138. [PMID: 30474121 DOI: 10.1002/jcu.22664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/01/2018] [Accepted: 10/09/2018] [Indexed: 06/09/2023]
Abstract
PURPOSE Macrovascular endothelial function is commonly assessed using flow-mediated dilation (FMD) and is nitric oxide (NO) dependent. However, the vasoreactivity to low flow during the FMD protocol may complement FMD interpretation. This study aimed to investigate in adolescents: (1) the day-to-day reliability of low-flow-mediated constriction (L-FMC) and composite vessel reactivity (CVR); and (2) the relationship between L-FMC and FMD. METHODS A retrospective analysis of data on 27 adolescents (14.3 ± 0.6 year, 12 males) was performed. Participants had two repeat measures, on separate days, of macrovascular function using high-resolution ultrasound for assessment of L-FMC, FMD, and CVR. RESULTS On average, the L-FMC response was vasoconstriction on both days (-0.59 ± 2.22% and -0.16 ± 1.50%, respectively). In contrast, an inconsistent response to low flow (vasoconstriction, dilation, or no change) was observed on an individual level. Cohen's Kappa revealed poor agreement for classifying the L-FMC measurement between visits (k = 0.04, P > .05). Assessment of the actual vessel diameter was robust with a coefficient of variation of 1.7% (baseline and peak) and 2.7% (low-flow). The between-day correlation coefficient between measures was r = .18, r = .96 and r = .52 for L-FMC, FMD, and CVR, respectively. No significant correlation between FMD and L-FMC was observed for either visit (r = -.06 and r = -.07, respectively; P > .05). CONCLUSION In adolescents, the low-flow vasoreactivity is inconsistent between days. Whereas the actual vessel diameter is reproducible, the measurement of L-FMC and CVR has poor between-day reliability compared to FMD. Finally, L-FMC, and FMD are not significantly correlated.
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Affiliation(s)
- Sascha H Kranen
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Bert Bond
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Craig A Williams
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Alan R Barker
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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7
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Ramalli A, Aizawa K, Shore AC, Morizzo C, Palombo C, Lenge M, Tortoli P. Continuous Simultaneous Recording of Brachial Artery Distension and Wall Shear Rate: A New Boost for Flow-Mediated Vasodilation. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2019; 66:463-471. [PMID: 30582536 DOI: 10.1109/tuffc.2018.2889111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vascular ultrasound has been extensively applied in the clinical setting to noninvasively assess the endothelial function by means of the so-called brachial artery flow mediated dilation (FMD). Despite the usefulness in large-scale epidemiological studies, this approach has revealed some pitfalls for assessing vascular physiology and health in individual subjects. Mainly, a reliable FMD examination should be based on the simultaneous and reliable measurement of both the stimulus, i.e., the wall shear rate (WSR), and the response, i.e., the diameter change. However, multiple technical, practical, and methodological challenges must be faced to meet this goal. In this work, we present the technical developments needed to implement a system to enable the extensive and reliable clinical ultrasound FMD examination. It integrates both a hardware part, i.e., an upgraded version of the ultrasound advanced open platform (ULA-OP), and a software part, i.e., a signal processing and data analysis platform. The system was applied for a two-center pilot clinical study on 35 young and healthy volunteers. Therefore, we present here the results of a statistical analysis on magnitude, time-course, and kinetic parameters of WSR and diameter trends that allowed us to accurately explore the vasodilatory response to the dynamic WSR changes. Our observations demonstrate that a direct and accurate estimation of WSR stimulus by multigate spectral Doppler allows understanding brachial artery vasodilatory response to reactive hyperemia. Drawing inferences on WSR stimulus from the diameter response along with an inaccurate estimation of WSR may cause further uncertainties for the accurate interpretation of the FMD response.
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8
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Aizawa K, Sbragi S, Ramalli A, Tortoli P, Casanova F, Morizzo C, Thorn CE, Shore AC, Gates PE, Palombo C. Brachial artery vasodilatory response and wall shear rate determined by multigate Doppler in a healthy young cohort. J Appl Physiol (1985) 2017; 124:150-159. [PMID: 28935823 DOI: 10.1152/japplphysiol.00310.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Wall shear rate (WSR) is an important stimulus for the brachial artery flow-mediated dilation (FMD) response. However, WSR estimation near the arterial wall by conventional Doppler is inherently difficult. To overcome this limitation, we utilized multigate Doppler to accurately determine the WSR stimulus near the vessel wall simultaneously with the FMD response using an integrated FMD system [Ultrasound Advanced Open Platform (ULA-OP)]. Using the system, we aimed to perform a detailed analysis of WSR-FMD response and establish novel WSR parameters in a healthy young population. Data from 33 young healthy individuals (27.5 ± 4.9 yr, 19 females) were analyzed. FMD was assessed with reactive hyperemia using ULA-OP. All acquired raw data were postprocessed using custom-designed software to obtain WSR and diameter parameters. The acquired velocity data revealed that nonparabolic flow profiles within the cardiac cycle and under different flow states, with heterogeneity between participants. We also identified seven WSR magnitude and four WSR time-course parameters. Among them, WSR area under the curve until its return to baseline was the strongest predictor of the absolute ( R2 = 0.25) and percent ( R2 = 0.31) diameter changes in response to reactive hyperemia. For the first time, we identified mono- and biphasic WSR stimulus patterns within our cohort that produced different magnitudes of FMD response [absolute diameter change: 0.24 ± 0.10 mm (monophasic) vs. 0.17 ± 0.09 mm (biphasic), P < 0.05]. We concluded that accurate and detailed measurement of the WSR stimulus is important to comprehensively understand the FMD response and that this advance in current FMD technology could be important to better understand vascular physiology and pathology. NEW & NOTEWORTHY An estimation of wall shear rate (WSR) near the arterial wall by conventional Doppler ultrasound is inherently difficult. Using a recently developed integrated flow-mediated dilation ultrasound system, we were able to accurately estimate WSR near the wall and identified a number of novel WSR variables that may prove to be useful in the measurement of endothelial function, an important biomarker of vascular physiology and disease.
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Affiliation(s)
- Kunihiko Aizawa
- Diabetes and Vascular Medicine Research Centre, National Institute of Health Research Exeter Clinical Research Facility, University of Exeter Medical School , Exeter , United Kingdom
| | - Sara Sbragi
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa , Pisa , Italy
| | - Alessandro Ramalli
- Department of Information Engineering, University of Florence , Florence , Italy
| | - Piero Tortoli
- Department of Information Engineering, University of Florence , Florence , Italy
| | - Francesco Casanova
- Diabetes and Vascular Medicine Research Centre, National Institute of Health Research Exeter Clinical Research Facility, University of Exeter Medical School , Exeter , United Kingdom
| | - Carmela Morizzo
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa , Pisa , Italy
| | - Clare E Thorn
- Diabetes and Vascular Medicine Research Centre, National Institute of Health Research Exeter Clinical Research Facility, University of Exeter Medical School , Exeter , United Kingdom
| | - Angela C Shore
- Diabetes and Vascular Medicine Research Centre, National Institute of Health Research Exeter Clinical Research Facility, University of Exeter Medical School , Exeter , United Kingdom
| | - Phillip E Gates
- Diabetes and Vascular Medicine Research Centre, National Institute of Health Research Exeter Clinical Research Facility, University of Exeter Medical School , Exeter , United Kingdom
| | - Carlo Palombo
- Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa , Pisa , Italy
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9
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Harbin MM, Ostrem JD, Evanoff NG, Kelly AS, Dengel DR. Intra- and inter-day reproducibility of low-flow mediated constriction response in young adults. Clin Physiol Funct Imaging 2017; 38:502-507. [PMID: 28574166 DOI: 10.1111/cpf.12448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 05/08/2017] [Indexed: 01/22/2023]
Abstract
PURPOSE When assessing brachial endothelial function by reactive hyperaemia, stopping blood flow creates a period of low-flow-mediated constriction (L-FMC). As little is known about how this parameter influences flow-mediated vasodilation (FMD), the purpose of this study was to better understand this relationship and to determine the intra- and interday reproducibility of brachial L-FMC. METHODS Brachial L-FMC and FMD were measured on 26 healthy, young adults (13 males, 13 females; 24·6 ± 2·7 years). Each participant had two assessments conducted on two separate visits, separated by a minimum of seven days. Brachial artery baseline diameter was imaged during rest. Continuous imaging of the artery was performed during the last 20 s of cuff-occlusion to 180 s postcuff release. An L-FMC was considered present if the relative change from pre-occlusion baseline to L-FMC artery diameter was less than -0·1%. RESULTS Overall, there was a strong, positive correlation between increased brachial L-FMC and blunted FMD (visit 1 test 1: r = 0·758, P<0·001; visit 1 test 2: r = 0·706, P<0·001; visit 2 test 1: r = 0·836, P<0·001; visit 2 test 2: r = 0·857, P<0·001). The reproducibility of intra- and interday L-FMC diameter was intraclass correlation coefficients (ICC) = 0·627, coefficient of variation (CV) = 54·4% and ICC = 0·734, CV = 43·5%, respectively. CONCLUSION Vasoconstriction to low-flow conditions influences the subsequent maximal dilation during reactive hyperaemia. However, L-FMC is variable as evidenced by the weak intra- and interday reproducibility of the measure. Further research should study brachial L-FMC reproducibility among varying populations and the implications L-FMC has on the interpretation of FMD results.
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Affiliation(s)
- Michelle M Harbin
- Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA
| | - Joseph D Ostrem
- Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA.,Kinesiology and Health Sciences, College of Education and Science, Concordia University, Paul, MN, USA
| | - Nicholas G Evanoff
- Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA
| | - Aaron S Kelly
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Donald R Dengel
- Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN, USA.,Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA
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10
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Aizawa K, Elyas S, Adingupu DD, Casanova F, Gooding KM, Strain WD, Shore AC, Gates PE. Reactivity to low-flow as a potential determinant for brachial artery flow-mediated vasodilatation. Physiol Rep 2016; 4:4/12/e12808. [PMID: 27335431 PMCID: PMC4923229 DOI: 10.14814/phy2.12808] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/30/2016] [Indexed: 01/17/2023] Open
Abstract
Previous studies have reported a vasoconstrictor response in the radial artery during a cuff-induced low-flow condition, but a similar low-flow condition in the brachial artery results in nonuniform reactivity. This variable reactivity to low-flow influences the subsequent flow-mediated dilatation (FMD) response following cuff-release. However, it is uncertain whether reactivity to low-flow is important in data interpretation in clinical populations and older adults. This study aimed to determine the influence of reactivity to low-flow on the magnitude of brachial artery FMD response in middle-aged and older individuals with diverse cardiovascular risk profiles. Data were analyzed from 165 individuals, divided into increased cardiovascular risk (CVR: n = 115, 85M, 67.0 ± 8.8 years) and healthy control (CTRL: n = 50, 30M, 63.2 ± 7.2 years) groups. Brachial artery diameter and blood velocity data obtained from Doppler ultrasound were used to calculate FMD, reactivity to low-flow and estimated shear rate (SR) using semiautomated edge-detection software. There was a significant association between reactivity to low-flow and FMD in overall (r = 0.261), CTRL (r = 0.410) and CVR (r = 0.189, all P < 0.05) groups. Multivariate regression analysis found that reactivity to low-flow, peak SR, and baseline diameter independently contributed to FMD along with sex, the presence of diabetes, and smoking (total R(2) = 0.450). There was a significant association between reactivity to low-flow and the subsequent FMD response in the overall dataset, and reactivity to low-flow independently contributed to FMD These findings suggest that reactivity to low-flow plays a key role in the subsequent brachial artery FMD response and is important in the interpretation of FMD data.
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Affiliation(s)
- Kunihiko Aizawa
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK
| | - Salim Elyas
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Damilola D Adingupu
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK
| | - Francesco Casanova
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK
| | - Kim M Gooding
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK
| | - W David Strain
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Angela C Shore
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK
| | - Phillip E Gates
- Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK
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