Enhanced external counterpulsation creates acute blood flow patterns responsible for improved flow-mediated dilation in humans

Gurovich, Alvaro N.; Braith, Randy W.

doi:10.1038/hr.2012.169

Cited by 50 publications

(62 citation statements)

References 40 publications

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“…During EECP, these cuffs are sequentially inflated, from distal to proximal, with target inflation pressures of 300 mmHg during cardiac diastole until rapid deflation immediately prior to systole. A single 45 min EECP session has been shown to acutely increase flow-mediated dilation (FMD) (Gurovich and Braith 2013), a surrogate of conduit artery endothelial function and nitric oxide bioavailability (Akhtar et al 2006). Chronically, administration of EECP has been shown to elicit significant improvements in FMD of the brachial (Hashemi et al 2008;Braith et al 2010;Beck et al 2014), femoral (Braith et al 2010;Beck et al 2014), and popliteal arteries .…”

Section: Introductionmentioning

confidence: 99%

Peripheral conduit and resistance artery function are improved following a single, 1-h bout of peristaltic pulse external pneumatic compression

2015

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Section: Introductionmentioning

confidence: 99%

Peripheral conduit and resistance artery function are improved following a single, 1-h bout of peristaltic pulse external pneumatic compression

2015

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“…37 At peak dilation brachial blood flow starts showing a bi-phasic flow pattern, with some retrograde laminar flow, as observed during resting measurements. Based on Womersley's approximation for pulsatile flows and an estimated hematocrit of 50%, 35,36 in the present study the blood-flow pattern at peak shear rate was confirmed as primarily antegrade and turbulent (data not shown). Normalizing FMD using AUC30 before peak dilation would include only antegrade laminar blood flow, which is known to guarantee endothelial activation.…”

Section: Discussionmentioning

confidence: 74%

“…14,15,23,24,32,33 AUC30 normalization is based on two physiological principles: (1) NO half-life 34 and (2) turbulent blood flow that might be present immediately after the cuff release, at the beginning of reactive hyperemia. 35 Peak FMD is normally observed 45-80 seconds after cuff deflation; 14 however, NO half-life is <10 seconds. 34 According to previous studies, 35,36 it is highly probable that blood flow during the first 15-30 seconds after cuff deflation is turbulent, which may inhibit endothelial function.…”

Section: Brachial Artery Flow-mediated Dilation (Fmd)mentioning

confidence: 99%

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Flow-mediated dilation is associated with endothelial oxidative stress in human venous endothelial cells

et al. 2014

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Endothelial dysfunction (ED) is the first pathophysiological step that produces atherosclerosis, which is responsible for ≈90% of all cardiovascular diseases. 1-4 ED is generally defined as the decrease in nitric oxide (NO) bio-availability within the endothelium, normally attributed to an increased endothelial oxidative stress. [1][2][3]5,6 In humans, early stages 7 and changes after interventions 8-10 of ED can be assessed non-invasively via flow-mediated dilation (FMD). [11][12][13][14][15] Briefly, FMD measures the dilatory capacity of a blood vessel, typically the brachial artery, which is exposed to a blood flow-induced stimulus (i.e. shear stress) elicited by reactive hyperemia. 12,13 Although FMD is recognized as a bioassay for ED, [11][12][13][14][15] with excellent clinical significance, 16,17 few studies have shown a relationship between FMD and endothelial oxidative stress in humans. 18 FMD is based on two physiological principles: (1) blood flow-induced shear stress activates the endothelium to produce NO; and (2) NO elicits vascular dilation via relaxation of vascular smooth muscle. 12,14 When there is an increased endothelial oxidative stress, endothelial NO synthase (eNOS) is uncoupled, producing a decrease in NO production and bioavailability. 5,6,19 Thus, an increased endothelial oxidative stress should decrease endothelial reactivity to shear stress, which will negatively impact FMD.Accordingly, the purpose of the present study was to determine if FMD is associated with endothelial oxidative Abstract Flow-mediated dilation (FMD) is recognized as a non-invasive endothelial function bioassay. However, FMD's relationship with endothelial cell oxidative stress in humans is yet to be determined. Here, we sought to determine if FMD was associated with endothelial nitric oxide synthase (eNOS) and endothelial oxidative stress in humans. Twenty-seven apparently healthy young men (26.5±5.9 years) underwent brachial artery FMD testing and endothelial cell biopsy from a forearm vein. Non-normalized FMD (%) and three different brachial artery FMD normalizations were performed: (1) peak shear rate (%/SR); (2) area under the SR curve until peak dilation (%/AUC); and (3) AUC 30 seconds before peak dilation (%/AUC30). Immunofluorescence quantification was used to assess eNOS expression and nitrotyrosine (NT), a criterion marker of endothelial oxidative stress. Values for eNOS and NT expression were reported as a ratio of endothelial cell to human umbilical vein endothelial cell average pixel intensity. NT expression was significantly correlated with FMD normalized by AUC30 (r = −0.402, p<0.05). Other FMD normalizations and non-normalized FMD were not significantly correlated with NT expression (r range = −0.364 to −0.142, all p>0.05). There were no significant correlations between eNOS expression and normalized and non-normalized FMD (r range = −0.168 to −0.066, all p>0.05). In conclusion, brachial artery FMD is associated with venous endothelial cell oxidative stress. However, this association is observed onl...

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“…Cuffs were inflated at a high pressure (up to 300 mmHg), which greatly altered arterial physiological hemodynamics [19], blood flow was retrograde and turbulent in the femoral artery but anterograde and laminar in the brachial artery [20]. Nevertheless, Gurovich et al [21] have shown, in a study that included 18 young men (25±4 years), that a single 45-min session of EECP with a pressure of 250 mmHg increased FMD in the femoral and brachial arteries compared with baseline, despite different blood flow patterns (retrograde-turbulent blood flow in the femoral artery and anterograde-laminar blood flow in the brachial artery). Both flow patterns created acute increases in endothelial shear stress.…”

Section: Discussionmentioning

confidence: 99%

Low-pressure sequential compression of lower limbs enhances forearm skin blood flow

Amah¹,

Voicu²,

Bonnin³

et al. 2016

CIM

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Low-pressure sequential compression of lower limbs enhances forearm skin blood flow Abstract Purpose: We investigated whether forearm skin blood flow could be improved when a multilayer pulsatile inflatable suit was applied at a low pressure to the lower limbs and abdomen. We hypothesized that a non-invasive purely mechanical stimulation of the lower limbs could induce remote forearm blood flow modifications. Methods:The pulsatile suit induced a sequential compartmentalized low compression (65 mmHg), which was synchronized with each diastole of the cardiac cycle with each phase evolving centripetally (lower limbs to abdomen). Modifications of the forearm skin blood flow were continuously recorded by laser Doppler flowmetry (LDF) at baseline and during the pulsatile suit application. Endothelium-dependent and endothelium-independent vasodilations of the forearm skin microcirculation were measured by LDF in response to a local transdermal iontophoretic application of acetylcholine (ACh-test) and to hyperthermia (hyperT-test).Results: Twenty-four healthy volunteers, 12 men and 12 women (43±14 years) were included in the study. LDF responses increased 1) under pulsatile suit (97±106%, p<0.01), 2) during ACh-test (338±336%, p<0.001) and 3) during hyperT-test (587±383%, p<0.001). No significant gender differences were seen. There was a significant linear positive regression between LDF response under pulsatile suit and during p=0.004). No adverse effects were reported.Conclusions: This proof-of-concept study shows that a sequential low-pressure compression applied to the lower limbs and abdomen induces a significant increase of the forearm skin blood flow, suggestive a systemic effect. Mechanisms still need to be investigated.

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Enhanced external counterpulsation creates acute blood flow patterns responsible for improved flow-mediated dilation in humans

Cited by 50 publications

References 40 publications

Peripheral conduit and resistance artery function are improved following a single, 1-h bout of peristaltic pulse external pneumatic compression

Peripheral conduit and resistance artery function are improved following a single, 1-h bout of peristaltic pulse external pneumatic compression

Flow-mediated dilation is associated with endothelial oxidative stress in human venous endothelial cells

Low-pressure sequential compression of lower limbs enhances forearm skin blood flow

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