Attenuation of Wave Reflection by Wave Entrapment Creates a "Horizon Effect" in the Human Aorta

Justin E. Davies; Jordi Alastruey; Darrel P. Francis; Nearchos Hadjiloizou; Zachary I. Whinnett; Charlotte H. Manisty; Jazmin Aguado-Sierra; Keith Willson; Rodney A. Foale; Iqbal S. Malik; Alun D. Hughes; Kim H. Parker; Jamil Mayet

doi:10.1161/HYPERTENSIONAHA.111.180604

Attenuation of Wave Reflection by Wave Entrapment Creates a "Horizon Effect" in the Human Aorta

Justin E. Davies, Jordi Alastruey, Darrel P. Francis, Nearchos Hadjiloizou, Zachary I. Whinnett, Charlotte H. Manisty, Jazmin Aguado-Sierra, Keith Willson, Rodney A. Foale, Iqbal S. Malik, Alun D. Hughes, Kim H. Parker, Jamil Mayet

Biomedical Engineering Department

Imperial College London

Research output: Contribution to journal › Article › peer-review

71 Citations (Scopus)

Abstract

Wave reflection is thought to be important in the augmentation of blood pressure. However, identification of distal reflections sites remains unclear. One possible explanation for this is that wave reflection is predominately determined by an amalgamation of multiple proximal small reflections rather than large discrete reflections originating from the distal peripheries. In 19 subjects (age, 35-73 years), sensor-tipped intra-arterial wires were used to measure pressure and Doppler velocity at 10-cm intervals along the aorta, starting at the aortic root. Incident and reflected waves were identified and timings and magnitudes quantified using wave intensity analysis. Mean wave speed increased along the length of the aorta (proximal, 6.8 +/- 0.9 m/s; distal, 10.7 +/- 1.5 m/s). The incident wave was tracked moving along the aorta, taking 55 +/- 4 ms to travel from the aortic root to the distal aorta. However, the timing to the refection site distance did not differ between proximal and distal aortic measurement sites (proximal aorta, 48 +/- 5 ms versus distal aorta, 42 +/- 4 ms; P=0.3). We performed a second analysis using aortic waveforms in a nonlinear model of pulse-wave propagation. This demonstrated very similar results to those observed in vivo and also an exponential attenuation in reflection magnitude. There is no single dominant refection site in or near the distal aorta. Rather, there are multiple reflection sites along the aorta, for which the contributions are attenuated with distance. We hypothesize that rereflection of reflected waves leads to wave entrapment, preventing distal waves being seen in the proximal aorta. (Hypertension. 2012; 60: 778-785.).

Original language	English
Pages (from-to)	778-785
Number of pages	8
Journal	Hypertension
Volume	60
Issue number	3
Early online date	16 Jul 2012
DOIs	https://doi.org/10.1161/HYPERTENSIONAHA.111.180604
Publication status	Published - Sept 2012

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10.1161/HYPERTENSIONAHA.111.180604

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Davies, J. E., Alastruey, J., Francis, D. P., Hadjiloizou, N., Whinnett, Z. I., Manisty, C. H., Aguado-Sierra, J., Willson, K., Foale, R. A., Malik, I. S., Hughes, A. D., Parker, K. H., & Mayet, J. (2012). Attenuation of Wave Reflection by Wave Entrapment Creates a "Horizon Effect" in the Human Aorta. Hypertension, 60(3), 778-785. https://doi.org/10.1161/HYPERTENSIONAHA.111.180604

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title = "Attenuation of Wave Reflection by Wave Entrapment Creates a {"}Horizon Effect{"} in the Human Aorta",

abstract = "Wave reflection is thought to be important in the augmentation of blood pressure. However, identification of distal reflections sites remains unclear. One possible explanation for this is that wave reflection is predominately determined by an amalgamation of multiple proximal small reflections rather than large discrete reflections originating from the distal peripheries. In 19 subjects (age, 35-73 years), sensor-tipped intra-arterial wires were used to measure pressure and Doppler velocity at 10-cm intervals along the aorta, starting at the aortic root. Incident and reflected waves were identified and timings and magnitudes quantified using wave intensity analysis. Mean wave speed increased along the length of the aorta (proximal, 6.8 +/- 0.9 m/s; distal, 10.7 +/- 1.5 m/s). The incident wave was tracked moving along the aorta, taking 55 +/- 4 ms to travel from the aortic root to the distal aorta. However, the timing to the refection site distance did not differ between proximal and distal aortic measurement sites (proximal aorta, 48 +/- 5 ms versus distal aorta, 42 +/- 4 ms; P=0.3). We performed a second analysis using aortic waveforms in a nonlinear model of pulse-wave propagation. This demonstrated very similar results to those observed in vivo and also an exponential attenuation in reflection magnitude. There is no single dominant refection site in or near the distal aorta. Rather, there are multiple reflection sites along the aorta, for which the contributions are attenuated with distance. We hypothesize that rereflection of reflected waves leads to wave entrapment, preventing distal waves being seen in the proximal aorta. (Hypertension. 2012; 60: 778-785.).",

author = "Davies, {Justin E.} and Jordi Alastruey and Francis, {Darrel P.} and Nearchos Hadjiloizou and Whinnett, {Zachary I.} and Manisty, {Charlotte H.} and Jazmin Aguado-Sierra and Keith Willson and Foale, {Rodney A.} and Malik, {Iqbal S.} and Hughes, {Alun D.} and Parker, {Kim H.} and Jamil Mayet",

year = "2012",

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doi = "10.1161/HYPERTENSIONAHA.111.180604",

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T1 - Attenuation of Wave Reflection by Wave Entrapment Creates a "Horizon Effect" in the Human Aorta

AU - Davies, Justin E.

AU - Alastruey, Jordi

AU - Francis, Darrel P.

AU - Hadjiloizou, Nearchos

AU - Whinnett, Zachary I.

AU - Manisty, Charlotte H.

AU - Aguado-Sierra, Jazmin

AU - Willson, Keith

AU - Foale, Rodney A.

AU - Malik, Iqbal S.

AU - Hughes, Alun D.

AU - Parker, Kim H.

AU - Mayet, Jamil

PY - 2012/9

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N2 - Wave reflection is thought to be important in the augmentation of blood pressure. However, identification of distal reflections sites remains unclear. One possible explanation for this is that wave reflection is predominately determined by an amalgamation of multiple proximal small reflections rather than large discrete reflections originating from the distal peripheries. In 19 subjects (age, 35-73 years), sensor-tipped intra-arterial wires were used to measure pressure and Doppler velocity at 10-cm intervals along the aorta, starting at the aortic root. Incident and reflected waves were identified and timings and magnitudes quantified using wave intensity analysis. Mean wave speed increased along the length of the aorta (proximal, 6.8 +/- 0.9 m/s; distal, 10.7 +/- 1.5 m/s). The incident wave was tracked moving along the aorta, taking 55 +/- 4 ms to travel from the aortic root to the distal aorta. However, the timing to the refection site distance did not differ between proximal and distal aortic measurement sites (proximal aorta, 48 +/- 5 ms versus distal aorta, 42 +/- 4 ms; P=0.3). We performed a second analysis using aortic waveforms in a nonlinear model of pulse-wave propagation. This demonstrated very similar results to those observed in vivo and also an exponential attenuation in reflection magnitude. There is no single dominant refection site in or near the distal aorta. Rather, there are multiple reflection sites along the aorta, for which the contributions are attenuated with distance. We hypothesize that rereflection of reflected waves leads to wave entrapment, preventing distal waves being seen in the proximal aorta. (Hypertension. 2012; 60: 778-785.).

AB - Wave reflection is thought to be important in the augmentation of blood pressure. However, identification of distal reflections sites remains unclear. One possible explanation for this is that wave reflection is predominately determined by an amalgamation of multiple proximal small reflections rather than large discrete reflections originating from the distal peripheries. In 19 subjects (age, 35-73 years), sensor-tipped intra-arterial wires were used to measure pressure and Doppler velocity at 10-cm intervals along the aorta, starting at the aortic root. Incident and reflected waves were identified and timings and magnitudes quantified using wave intensity analysis. Mean wave speed increased along the length of the aorta (proximal, 6.8 +/- 0.9 m/s; distal, 10.7 +/- 1.5 m/s). The incident wave was tracked moving along the aorta, taking 55 +/- 4 ms to travel from the aortic root to the distal aorta. However, the timing to the refection site distance did not differ between proximal and distal aortic measurement sites (proximal aorta, 48 +/- 5 ms versus distal aorta, 42 +/- 4 ms; P=0.3). We performed a second analysis using aortic waveforms in a nonlinear model of pulse-wave propagation. This demonstrated very similar results to those observed in vivo and also an exponential attenuation in reflection magnitude. There is no single dominant refection site in or near the distal aorta. Rather, there are multiple reflection sites along the aorta, for which the contributions are attenuated with distance. We hypothesize that rereflection of reflected waves leads to wave entrapment, preventing distal waves being seen in the proximal aorta. (Hypertension. 2012; 60: 778-785.).

U2 - 10.1161/HYPERTENSIONAHA.111.180604

DO - 10.1161/HYPERTENSIONAHA.111.180604

M3 - Article

SN - 0194-911X

VL - 60

SP - 778

EP - 785

JO - Hypertension

JF - Hypertension

IS - 3

ER -

Attenuation of Wave Reflection by Wave Entrapment Creates a "Horizon Effect" in the Human Aorta

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