Hemodynamic Factors Changing Blood Flow Velocity Waveform and Profile in Normal Human Brachial Artery

Baccelli, G; Pignoli, P; Corbellini, Ezio; Pizzolati, Pier Luigi; Bassini, Mario; Longo, T; Zanchetti, Alberto

doi:10.1177/000331978503600101

Cited by 21 publications

(21 citation statements)

References 6 publications

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“…The current results may indeed be explained by this classic work. Our rationale was that increased MSNA would lead to increases in downstream vascular resistance, thus enhancing retrograde flow as previously suggested (2). While this was noted in situations in which arterial blood pressure remained unchanged, when blood pressure was concomitantly increased with MSNA, this may have altered the pressure gradient to one that favored decreases in retrograde flow.…”

Section: Discussionmentioning

confidence: 92%

“…The rationale for considering elevated MSNA as a potential candidate stemmed from previous reports proposing that increased peripheral vascular resistance may influence flow profiles (2,29). Indeed, the well-characterized observation that conduit artery blood flow is entirely antegrade during reactive hyperemia (induced by transient occlusion) suggests that retrograde flow can be abolished when selectively lowering downstream vascular resistance (29).…”

Section: Discussionmentioning

confidence: 99%

“…In consideration of the recognized impact of oscillatory shear patterns on vascular phenotype, it appears fundamental to devote efforts toward elucidating factors that may influence flow profiles in peripheral conduit arteries. Previous (2) and more recent (33) observations that inflating a pressure cuff on the forearm results in greater retrograde flow at the brachial artery strongly suggests that changes in peripheral vascular resistance may explain differences in flow patterns. On this basis, it is tempting to speculate that factors altering vascular tone may be prime candidates participating in the regulation of upstream oscillatory shear patterns.…”

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confidence: 95%

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Increased muscle sympathetic nerve activity acutely alters conduit artery shear rate patterns

Padilla¹,

Young²,

Simmons³

et al. 2010

American Journal of Physiology-Heart and Circulatory Physiology

107

119

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Padilla J, Young CN, Simmons GH, Deo SH, Newcomer SC, Sullivan JP, Laughlin MH, Fadel PJ. Increased muscle sympathetic nerve activity acutely alters conduit artery shear rate patterns. Am J Physiol Heart Circ Physiol 298: H1128 -H1135, 2010. First published February 12, 2010 doi:10.1152/ajpheart.01133.2009.-Escalating evidence indicates that disturbed flow patterns, characterized by the presence of retrograde and oscillatory shear stress, induce a proatherogenic endothelial cell phenotype; however, the mechanisms underlying oscillatory shear profiles in peripheral conduit arteries are not fully understood. We tested the hypothesis that acute elevations in muscle sympathetic nerve activity (MSNA) are accompanied by increases in conduit artery retrograde and oscillatory shear. Fourteen healthy men (25 Ϯ 1 yr) performed three sympathoexcitatory maneuvers: graded lower body negative pressure (LBNP) from 0 to Ϫ40 Torr, cold pressor test (CPT), and 35% maximal voluntary contraction handgrip followed by postexercise ischemia (PEI). MSNA (microneurography; peroneal nerve), arterial blood pressure (finger photoplethysmography), and brachial artery velocity and diameter (duplex Doppler ultrasound) in the contralateral arm were recorded continuously. All maneuvers elicited significant increases in MSNA total activity from baseline (P Ͻ 0.05). Retrograde shear (Ϫ3.96 Ϯ 1.2 baseline vs. Ϫ8.15 Ϯ 1.8 s Ϫ1 , Ϫ40 LBNP, P Ͻ 0.05) and oscillatory shear index (0.09 Ϯ 0.02 baseline vs. 0.20 Ϯ 0.02 arbitrary units, Ϫ40 LBNP, P Ͻ 0.05) were progressively augmented during graded LBNP. In contrast, during CPT and PEI, in which MSNA and blood pressure were concomitantly increased (P Ͻ 0.05), minimal or no changes in retrograde and oscillatory shear were noted. These data suggest that acute elevations in MSNA are associated with an increase in conduit artery retrograde and oscillatory shear, an effect that may be influenced by concurrent increases in arterial blood pressure. Future studies should examine the complex interaction between MSNA, arterial blood pressure, and other potential modulatory factors of shear rate patterns. sympathetic tone; blood pressure; blood flow; endothelium; atherosclerosis ATHEROSCLEROSIS IS A POTENTIALLY life-threatening disease of large and medium-size arteries that is strongly associated with systemic risk factors such as physical inactivity, obesity, hypercholesterolemia, hypertension, smoking, and diabetes (30). However, the predictable distribution of atherosclerosis indicates that localized hemodynamic environments may also influence the atherosclerotic disease process (31). Indeed, postmortem (36) and in vivo imaging studies (10) demonstrate that atherosclerotic lesions are preferentially located in regions distinguished by oscillatory (bidirectional blood flow) and low mean shear stress, whereas areas exposed to unidirectional and moderate shear are protected. A causal link between disturbed flow patterns and a proatherogenic endothelial cell phenotype has been extensively confirmed by in vitro studi...

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 95%

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Increased muscle sympathetic nerve activity acutely alters conduit artery shear rate patterns

Padilla¹,

Young²,

Simmons³

et al. 2010

American Journal of Physiology-Heart and Circulatory Physiology

107

119

View full text Add to dashboard Cite

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“…4 In humans, acute rises in sympathetic vasoconstrictor nerve traffic to skeletal muscle, as elicited reflexively by graded lower body negative pressure, increase conduit artery retrograde and oscillatory shear rates. 3 Stepwise increases in brachial artery retrograde flow, induced by distal cuff inflation, influence only slightly antegrade flow, but augment markedly retrograde peak velocity 5 and attenuate flow-mediated dilation. 6 Thus, our interpretation of the observation illustrated is that, in this individual, spontaneous OSA triggered hypoxia-induced sympathetic activation causing arteriolar vasoconstriction.…”

Section: Neurogenic Retrograde Arterial Flow During Obstructive Sleepmentioning

confidence: 99%

Neurogenic Retrograde Arterial Flow During Obstructive Sleep Apnea: A Novel Mechanism for Endothelial Dysfunction?

Millar¹,

Murai²,

Floras

2011

Hypertension

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Letters to the Editor will be published, if suitable, as space permits. They should not exceed 1000 words (typed double-spaced) in length and may be subject to editing or abridgment. Neurogenic Retrograde Arterial Flow During Obstructive Sleep Apnea: A Novel Mechanism for Endothelial Dysfunction?To the Editor: Patients with obstructive sleep apnea (OSA) exhibit impaired brachial artery flow-mediated dilation during wakefulness, a phenomenon that has been attributed to a carryover into the awake state of the consequences of recurrent cycles of hypoxia and reperfusion during sleep, resulting in decreased NO bioavailability and vascular inflammation. 1 However, recent prospective studies have failed to identify clearly an independent predictive relationship between markers of oxidative stress and endothelial function. 2 Our unanticipated detection of retrograde arterial flow during spontaneous obstructive apnea in an experimental subject who fell asleep when studied during the daytime leads us to propose a novel, additional mechanism for the development of this marker of endothelial dysfunction.A 67-year-old man (blood pressure: 142/84 mm Hg; heart rate: 49 bpm) with known severe untreated OSA (apnea-hypopnea index: 63 events per hour) and treated hypertension (40 mg of fosinopril), whose apneas precipitated marked arterial oxygen desaturation (down to 60%), was participating in a study of muscle sympathetic nerve activity in hypertension. The experimental protocol entailed simultaneous measurements of breathing, continuous digital blood pressure (Portapres, Finapres Medical Systems BV, Amsterdam, the Netherlands), heart rate, muscle sympathetic nerve activity (microneurography), and assessment of brachial artery diameter and blood velocity (Vivid 7, GE Medical Systems, Milwaukee, WI) to determine the flow-mediated vasodilator response. All of the study protocols were approved by the University Health Network Research Ethics Board, and informed written consent was obtained.During the acquisition of baseline measurements, the subject drifted off to sleep and was observed to spontaneously develop cycles of obstructive apnea. As anticipated, these were accompanied by marked increases in efferent muscle sympathetic nerve activity ( Figure A). Not expected was the conversion of unidirectional brachial artery flow during normal breathing to an oscillation between antegrade and retrograde flow during apneas ( Figure A and B). To our knowledge, this is the first reported description of this vascular phenomenon with spontaneous apneas. Anecdotal evidence suggests that this observation may also be present with voluntary apneas in healthy younger men. 3 In experimental models, retrograde and oscillatory shear stress profiles can promote atherogenic and thrombogenic vascular states. 4 In humans, acute rises in sympathetic vasoconstrictor nerve traffic to skeletal muscle, as elicited reflexively by graded lower body negative pressure, increase conduit artery retrograde and oscillatory shear rates. 3 Stepwise increases in brach...

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“…The pressure gradient generated by a stenosis can be mea sured as can the reduction in blood flow and alterations in the velocity pulse both proximally and distally to the lesion [5].…”

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confidence: 99%

Ultrasound Evaluation of Atherosclerosis

Pignoli¹,

Longo²

1986

Eur Surg Res

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The evaluation of atherosclerosis requires the definition of the object to be measured and of the questions the investigation is required to answer. In the first part of this paper some of the problems that arise when planning and defining evaluation of atherosclerosis are discussed. The second part is a review of the principal methods based on ultrasound technology. The working principles and clinical applications of each method are discussed. The rationale of each type of instrument with respect to others is highlighted.

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Hemodynamic Factors Changing Blood Flow Velocity Waveform and Profile in Normal Human Brachial Artery

Cited by 21 publications

References 6 publications

Increased muscle sympathetic nerve activity acutely alters conduit artery shear rate patterns

Increased muscle sympathetic nerve activity acutely alters conduit artery shear rate patterns

Neurogenic Retrograde Arterial Flow During Obstructive Sleep Apnea: A Novel Mechanism for Endothelial Dysfunction?

Ultrasound Evaluation of Atherosclerosis

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