title: Reactivity to low-flow as a potential determinant for brachial artery flow-mediated vasodilatation.
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.
authors.affiliation: Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK k.aizawa@exeter.ac.uk.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Aizawa
authors.affiliation: 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.
authors.forename: Salim
authors.initials: S
authors.lastname: Elyas
authors.affiliation: Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK.
authors.forename: Damilola D
authors.initials: DD
authors.lastname: Adingupu
authors.affiliation: Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Casanova
authors.affiliation: Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK.
authors.forename: Kim M
authors.initials: KM
authors.lastname: Gooding
authors.affiliation: 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.
authors.forename: W David
authors.initials: WD
authors.lastname: Strain
authors.affiliation: Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: Diabetes and Vascular Medicine Research Centre, University of Exeter Medical School, Exeter, UK NIHR Exeter Clinical Research Facility, Exeter, UK.
authors.forename: Phillip E
authors.initials: PE
authors.lastname: Gates
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001916:Brachial Artery / Q000254:growth & development / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D018056:Hemorheology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014664:Vasodilation
keywords: Brachial artery; cardiovascular disease; endothelial function; shear stress; ultrasound