A real-time device for converting Doppler ultrasound audio signals into fluid flow velocity

Herr, Michael D.; Hogeman, Cynthia S.; Koch, Dennis W.; Krishnan, Anandi; Momen, Afsana; Leuenberger, Urs A.

doi:10.1152/ajpheart.00713.2009

Cited by 62 publications

(54 citation statements)

References 18 publications

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“…With the use of technology developed by Herr et al (18), the Doppler audio information from the ultrasound was converted into a real-time digital flow velocity signal using fast Fourier transform (18). This method of signal processing has been validated by both in vitro and in vivo methods (18). Beat-to-beat brachial artery blood velocity and blood pressure (arterial catheter; Transpac IV Monitoring Kit; ICU Medical; San Clemente, CA) were obtained throughout each trial.…”

Section: Methodsmentioning

confidence: 99%

β-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase

Limberg

Johansson

Peltonen

et al. 2016

American Journal of Physiology-Heart and Circulatory Physiology

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Limberg JK, Johansson RE, Peltonen GL, Harrell JW, Kellawan JM, Eldridge MW, Sebranek JJ, Schrage WG. ␤-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase. Am J Physiol Heart Circ Physiol 310: H756 -H764, 2016. First published January 8, 2016 doi:10.1152/ajpheart.00886.2015.-We tested the hypothesis that women exhibit greater vasodilator responses to ␤-adrenoceptor stimulation compared with men. We further hypothesized women exhibit a greater contribution of nitric oxide synthase and cyclooxygenase to ␤-adrenergic-mediated vasodilation compared with men. Forearm blood flow (Doppler ultrasound) was measured in young men (n ϭ 29, 26 Ϯ 1 yr) and women (n ϭ 33, 25 Ϯ 1 yr) during intra-arterial infusion of isoproterenol (␤-adrenergic agonist). In subset of subjects, isoproterenol responses were examined before and after local inhibition of nitric oxide synthase [N Gmonomethyl-L-arginine (L-NMMA); 6 male/10 female] and/or cyclooxygenase (ketorolac; 5 male/5 female). Vascular conductance (blood flow Ϭ mean arterial pressure) was calculated to assess vasodilation. Vascular conductance increased with isoproterenol infusion (P Ͻ 0.01), and this effect was not different between men and women (P ϭ 0.41). L-NMMA infusion had no effect on isoproterenol-mediated dilation in men (P Ͼ 0.99) or women (P ϭ 0.21). In contrast, ketorolac infusion markedly increased isoproterenol-mediated responses in both men (P Ͻ 0.01) and women (P ϭ 0.04) and this rise was lost with subsequent L-NMMA infusion (men, P Ͻ 0.01; women, P Ͻ 0.05). ␤-Adrenergic vasodilation is not different between men and women and sex differences in the independent contribution of nitric oxide synthase and cyclooxygenase to ␤-mediated vasodilation are not present. However, these data are the first to demonstrate ␤-adrenoceptor activation of cyclooxygenase suppresses nitric oxide synthase signaling in human forearm microcirculation and may have important implications for neurovascular control in both health and disease.isoproterenol; blood flow; prostaglandin; sex differences; skeletal muscle NEW & NOTEWORTHYIn contrast to present thought, ␤-adrenergic-mediated vasodilation, and the independent contributions of nitric oxide synthase and cyclooxygenase, are remarkably similar in young men and women. These data are also the first to demonstrate ␤-adrenoceptor activation of the cyclooxygenase pathway actively suppresses nitric oxide synthase signaling in human forearm microcirculation.YOUNG WOMEN EXHIBIT LOWER cardiovascular disease risk compared with men (26). Part of this cardioprotection may be attributed to increased peripheral ␤-adrenergic-mediated vasodilation. For example, the relationship between sympathetic nervous system activity and total peripheral resistance observed in young men is present in women only during ␤-adrenoceptor blockade (16). Furthermore, when ␤-adrenoceptors are blocked, sympathetically-mediated vasoconstriction is increased in women but not in men (16). Consistent with this idea, young wom...

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Section: Methodsmentioning

confidence: 99%

β-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase

Limberg

Johansson

Peltonen

et al. 2016

American Journal of Physiology-Heart and Circulatory Physiology

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“…In Protocols 1 and 3, a commercial interface unit (Multigon Industries, Yonkers, NY) processed the angle-corrected, intensity-weighted Doppler audio information into a flow velocity signal that was sampled in real time. In Protocol 2, the Doppler audio information was converted into a real-time digital flow velocity signal using Fast Fourier Transform (Herr et al 2010). This method of signal processing has been validated by both in vitro and in vivo methods (Herr et al 2010).…”

Section: Methodsmentioning

confidence: 99%

“…In Protocol 2, the Doppler audio information was converted into a real-time digital flow velocity signal using Fast Fourier Transform (Herr et al 2010). This method of signal processing has been validated by both in vitro and in vivo methods (Herr et al 2010). All data were recorded continuously on a computer and analyzed offline (PowerLab Chart5, ADInstruments, Colorado Springs, CO).…”

Section: Methodsmentioning

confidence: 99%

Potentiation of the NO-cGMP pathway and blood flow responses during dynamic exercise in healthy humans

Limberg

Malterer

Kellawan³

et al. 2016

Eur J Appl Physiol

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Purpose Previous work has shown nitric oxide (NO) contributes to ~15% of the hyperemic response to dynamic exercise in healthy humans. This NO-mediated vasodilation occurs, in part, via increases in intracellular cyclic guanosine monophosphate (cGMP), which is catabolized by phosphodiesterase. We sought to examine the effect of phosphodiesterase-5 (PDE-5) inhibition on forearm blood flow (FBF responses to dynamic handgrip exercise in healthy humans and the role of NO. We hypothesized exercise hyperemia would be augmented by sildenafil citrate (SDF, PDE-5 inhibitor). We further hypothesized any effect of SDF on exercise hyperemia would be abolished with intra-arterial infusion of the NO synthase (NOS) inhibitor L-NG-monomethyl arginine (L-NMMA). Methods FBF (Doppler ultrasound) was assessed at rest and during 5 minutes of dynamic forearm handgrip exercise at 15% of maximal voluntary contraction under control (saline) conditions and during 3 experimental protocols: 1) oral SDF (n=10), 2) intra-arterial L-NMMA (n=20), 3) SDF and L-NMMA (n=10). FBF responses to intra-arterial sodium nitroprusside (NTP, NO donor) were also assessed. Results FBF increased with exercise (p<0.01). Intra-arterial infusion of L-NMMA resulted in a reduction in exercise hyperemia (17±1 to 15±1 mL/dL/min, p<0.01). Although the hyperemic response to NTP was augmented by SDF (Area under the curve: 41±7 vs 61±11 AU, p<0.01), there was no effect of SDF on exercise hyperemia (p=0.33). Conclusions Despite improving NTP-mediated vasodilation, oral SDF failed to augment exercise hyperemia in young, healthy adults. These observations reflect a minor contribution of NO and the cGMP pathway during exercise hyperemia in healthy young humans.

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“…Measurements were made with a fixed insonation angle of ≤60°, with the sample volume adjusted to cover the width of the brachial artery (Limberg et al 2010, 2013). The audio signal from the Vivid 7 was sampled real-time by a custom-made device which converted velocity information into a digital signal using fast Fourier transform, which was calibrated to a specific pulsed Doppler frequency (5 MHz) (Herr et al 2010). Brachial arterial diameter was measured on B-mode images in the part of the artery running perpendicular to the ultrasound beam (Limberg et al 2010, 2013).…”

Section: Methodsmentioning

confidence: 99%

Exercise vasodilation is greater in women: contributions of nitric oxide synthase and cyclooxygenase

et al. 2015

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Purpose We hypothesized exercise vasodilation would be greater in women due to nitric oxide synthase (NOS) and cyclooxygenase (COX) signaling. Methods 45 healthy adults (23 women, W, 22 men, M, 26 ± 1 years) completed two 10-min trials of dynamic forearm exercise at 15 % intensity. Forearm blood flow (FBF; Doppler ultrasound), arterial pressure (brachial catheter), and forearm lean mass were measured to calculate relative forearm vascular conductance (FVCrel) = F BF 100 mmHg−1 100 g−1 lean mass. Local intra-arterial infusion of L-NMMA or ketorolac acutely inhibited NOS and COX, respectively. In Trial 1, the first 5 min served as control exercise (CON), followed by 5 min of L-NMMA or ketorolac over the last 5 min of exercise. In Trial 2, the remaining drug was infused during 5–10 min, to achieve combined NOS–COX inhibition (double blockade, DB). Results Are mean ± SE. Women exhibited 29 % greater vasodilation in CON (AFVCrel, 19 ± 1 vs. 15 ± 1, p = 0.01). L-NMMA reduced AFVCrel (p < 0.001) (W: Δ −2.3 ± 1.3 vs. M: Δ −3.7 ± 0.8, p = 0.25); whereas, ketorolac modestly increased ΔFVCrel (p = 0.04) similarly between sexes (W: Δ 1.6 ± 1.1 vs. M: Δ 2.0 ± 1.6, p = 0.78). DB was also found to be similar between the sexes (p = 0.85). Conclusion These data clearly indicate women produce a greater exercise vasodilator response. Furthermore, contrary to experiments in animal models, these data are the first to demonstrate vascular control by NOS and COX is similar between sexes.

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A real-time device for converting Doppler ultrasound audio signals into fluid flow velocity

Cited by 62 publications

References 18 publications

β-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase

β-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase

Potentiation of the NO-cGMP pathway and blood flow responses during dynamic exercise in healthy humans

Exercise vasodilation is greater in women: contributions of nitric oxide synthase and cyclooxygenase

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