�ber ein ventilloses Pumpprinzip

Liebau, G.

doi:10.1007/bf00644490

Cited by 79 publications

(72 citation statements)

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“…Liebau became interested in valveless pumping phenomena as a result of his own observations on the hemodynamics of the healthy and failing human cardiovascular system. He constructed and tested physical models for the peripheral vascular bed and for the embryonic and mature human heart and, thereby, discovered a valveless pumping phenomenon that was unknown at his time (Liebau, 1954a(Liebau, ,b, 1955a(Liebau, ,b, 1968(Liebau, , 1970. The simplest physical model in which he observed this pumping phenomenon-later called the ''Liebau effect'' (Moser et al, 1998;Kenner, 2004)-was an open tube system consisting of a water-filled flexible tube of finite length placed horizontally in a water-filled bath (Liebau, 1955a).…”

Section: Historical Evolution Of the Liebau Pump Theorymentioning

confidence: 99%

“…Apart from his speculations on the pumping action of tubular hearts, Liebau used his observations on physical models primarily to explain some physiological as well as some clinically important pathophysiological phenomena of the mature human cardiovascular system (Liebau, 1954a(Liebau, ,b, 1955a(Liebau, ,b, 1968(Liebau, , 1970. It thus might be surprising to note that the Liebau effect has remained unnoticed by the majority of physicians and biologists for a long time.…”

Section: Historical Evolution Of the Liebau Pump Theorymentioning

confidence: 99%

“…Recent hemodynamic data from zebrafish embryos suggest that the tubular hearts of vertebrate embryos are dynamic suction pumps that work on the basis of the so-called Liebau effect (Forouhar et al, 2006). This effect is a nonperistaltic valveless pumping phenomenon that was discovered in physical models of valveless tubular pumps-so-called ''Liebau pumps''-in the 1950s (Liebau, 1954a(Liebau, ,b, 1955a. The Liebau effect is relatively unknown among biologists and physicians.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

How does the tubular embryonic heart work? Looking for the physical mechanism generating unidirectional blood flow in the valveless embryonic heart tube

Männer

Wessel

Yelbuz

2010

Developmental Dynamics

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The heart is the first organ to function in vertebrate embryos. The human heart, for example, starts beating around the 21st embryonic day. During the initial phase of its pumping action, the embryonic heart is seen as a pulsating blood vessel that is built up by (1) an inner endothelial tube lacking valves, (2) a middle layer of extracellular matrix, and (3) an outer myocardial tube. Despite the absence of valves, this tubular heart generates unidirectional blood flow. This fact poses the question how it works. Visual examination of the pulsating embryonic heart tube shows that its pumping action is characterized by traveling mechanical waves sweeping from its venous to its arterial end. These traveling waves were traditionally described as myocardial peristaltic waves. It has, therefore, been speculated that the tubular embryonic heart works as a technical peristaltic pump. Recent hemodynamic data from living embryos, however, have shown that the pumping function of the embryonic heart tube differs in several respects from that of a technical peristaltic pump. Some of these data suggest that embryonic heart tubes work as valveless ''Liebau pumps.'' In the present study, a review is given on the evolution of the two above-mentioned theories of early cardiac pumping mechanics. We discuss pros and cons for both of these theories. We show that the tubular embryonic heart works neither as a technical peristaltic pump nor as a classic Liebau pump. The question regarding how the embryonic heart tube works still awaits an answer.

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Section: Historical Evolution Of the Liebau Pump Theorymentioning

confidence: 99%

Section: Historical Evolution Of the Liebau Pump Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

How does the tubular embryonic heart work? Looking for the physical mechanism generating unidirectional blood flow in the valveless embryonic heart tube

Männer

Wessel

Yelbuz

2010

Developmental Dynamics

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“…The ability to reverse flow direction by adjusting the frequency of excitations has been reported in several open and closed loop experimental set ups. 10,11,14,6 In the MIP positive flow, i.e., flow exiting the pump from the extremity the farthest to the compression zone, is achieved for frequencies close to the resonant frequency ͓f = ͑9 Hz, 12 Hz͔͒ and reaches maximum at resonance ͑f res = 10.1 Hz͒. Negative flow is observed at frequencies below the resonant frequency ͓f = ͑8 Hz,9 Hz͔͒.…”

Section: -9mentioning

confidence: 99%

Resonant pumping in a multilayer impedance pump

2008

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This paper introduces the concept of multilayer impedance pump, a novel pumping mechanism inspired by the embryonic heart structure. The pump is a composite two-layer fluid-filled elastic tube featuring a thick gelatinous internal. Pumping is based on the impedance pumping mechanism. In an impedance pump, elastic waves are generated upon external periodic compressions of the elastic tube. These waves propagate along the tube's walls, reflect at the tube's extremities, and drive the flow in a preferential direction. The originality in the multilayer impedance pump design relies on the use of the thick internal gelatinous layer to amplify the elastic waves responsible for the pumping. As a consequence, only small excitations are needed to produce significant flow. This fully coupled fluid-structure interaction problem is solved for the flow and the structure using the finite element method over a relevant range of frequencies of excitation. Results show that the multilayer impedance pump is a complex system that exhibits a resonant response. Flow output and inner wall motion are maximal when the pump is actuated at the resonant frequency. The wave interaction mechanism present in an impedance pump is described here in details for the case of a multilayer impedance pump. Using energy balance for the passive portion of the elastic tube, we show that the elastic tube itself works as a pump and that at resonance maximum energy transmission between the elastic tube and the fluid occurs. Finally, the pump is especially suitable for many biomedical applications.

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“…William Harvey, in his 1628 treatise entitled "De Motu Cordis et Sanguinis" assigned the movement of blood around the cardiovascular circuit to the valve equipped pumping heart alone (Harvey, 1628). During the 1950s, the physician Liebau (Liebau, 1954) challenged this position by demonstrating that valveless, fluid dynamic, closed loop models of his own construction could generate average flow around the closed loop as a result of periodic local compression and release. Despite support by fluid-dynamicists, Liebau was unable to offer an explanation and interest waned until a quantitative interpretation was published in 1998 (Moser et al, 1998).…”

Section: Discussionmentioning

confidence: 99%