The area ratio of normal arterial junctions and its implications in pulse wave reflections

Papageorgiou, G.L.; Jones, Barrie N; Redding, V. J.; Hudson, Norah M.

doi:10.1093/cvr/24.6.478

Cited by 35 publications

(28 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is in close agreement with the data on arteries by Suwa and co‐workers ( K A,k ~ 1·19, Suwa et al. 1963; Milnor 1989) and Papageorgiou and co‐workers ( K A,k ~ 1·14, Papageorgiou et al. 1990; Brown 1993), all favouring the constant wall‐thickness model.…”

Section: Critical Assumptionssupporting

confidence: 91%

Revisiting the evolutionary origin of allometric metabolic scaling in biology

Apol¹,

Etienne

Olff

2008

Functional Ecology

View full text Add to dashboard Cite

Summary 1.In 1997 West, Brown & Enquist published a theoretical explanation for the long-known empirical observation of 3/4-power scaling of organismal metabolic rates with body mass, using an attractive combination of general physical and physiological principles with evolutionary optimization. This model generated hundreds of studies, exploring its implications for physiology, populations, biodiversity, whole-ecosystem functioning, and even medical, engineering and social sciences. 2. However, the evolutionary optimization part of the model has never been carefully scrutinized. 3. In this article we perform the evolutionary optimization as proposed by the authors rigorously and show that it actually leads to a biologically irrelevant network, i.e. a single vessel. 4. Moreover, we find that by relaxing some assumptions in a realistic way we obtain a feasible network but with isometric scaling of metabolism, which is in conflict with Kleiber's empirical law of an allometric exponent of around 3/4. 5. Hence, we conclude that the West-Brown-Enquist model cannot account for the observed universal metabolic scaling relation. 6. As possible solutions to this paradox, we discuss (weak) body-size dependence of capillary properties (leading to different predictions of intra-and inter-specific metabolic scaling), and expanding the West-Brown-Enquist model to an integrated network model (including body shape and oxygen transport to and from the arterial system). Alternatively, the ultimate explanation for the observed allometric patterns may need to be found outside the framework of flow-limited network theory. 7. We conclude that Kleiber's law is still as theoretically unexplained as ecologically important.

show abstract

Section: Critical Assumptionssupporting

confidence: 91%

Revisiting the evolutionary origin of allometric metabolic scaling in biology

Apol¹,

Etienne

Olff

2008

Functional Ecology

View full text Add to dashboard Cite

show abstract

“…When the waves encounter a change in the properties of the vessel, either at a bifurcation or a resistance element used to model the terminal vessels of our model, they are reflected and transmitted with magnitudes determined by a reflection coefficient which depend upon the properties of the vessels at the junction. From measurements of the geometrical and elastic properties of arterial bifurcations, it has been suggested that most arterial junctions are well matched for forward wave transmission so that RE0 (Papageorgiou and Jones, 1988;Papageorgiou et al, 1990). A less-well-recognised implication of this observation is that the arterial system is poorly matched for backward waves because a bifurcation well matched in one direction is necessarily ill matched in the other.…”

Section: Discussionmentioning

confidence: 99%

Wave propagation in a model of the arterial circulation

Wang

Parker

2004

Journal of Biomechanics

229

247

View full text Add to dashboard Cite

“…We also see that there is no reflection, C = 0 for symmetrical bifurcations if a % 1:15; This is generally referred to as the well-matched condition. Interestingly, extensive measurements of area ratios of human arterial bifurcations found a mean value a = 1.14 ± 0.03 [11]. Looking only at the coronary circulation, they found a mean value a = 1.18 ± 0.04.…”

Section: Reflection and Transmission Of Wavesmentioning

confidence: 99%

An introduction to wave intensity analysis

Parker

2009

Med Biol Eng Comput

277

324

View full text Add to dashboard Cite

Wave intensity analysis applies methods first used to study gas dynamics to cardiovascular haemodynamics. It is based on the method of characteristics solution of the 1-D equations derived from the conservation of mass and momentum in elastic vessels. The measured waveforms of pressure P and velocity U are described as the summation of successive wavefronts that propagate forward and backward through the vessels with magnitudes dP (+/-) and dU (+/-). The net wave intensity dPdU is the flux of energy per unit area carried by the wavefronts. It is positive for forward waves and negative for backward waves, providing a convenient tool for quantifying the timing, direction and magnitude of waves. Two methods, the PU-loop and the sum of squares, are given for calculating the wave speed c from simultaneous measurements of P and U at a single location. Given c, it is possible to separate the waveforms into their forward and backward components. Finally, the reservoir-wave hypothesis that the arterial and venous pressure can be conveniently thought of as the sum of a reservoir pressure arising from the total compliance of the vessels (the Windkessel effect) and the pressure associated with the waves is discussed.

show abstract

The area ratio of normal arterial junctions and its implications in pulse wave reflections

Cited by 35 publications

References 0 publications

Revisiting the evolutionary origin of allometric metabolic scaling in biology

Revisiting the evolutionary origin of allometric metabolic scaling in biology

Wave propagation in a model of the arterial circulation

An introduction to wave intensity analysis

Contact Info

Product

Resources

About