Herzpulsation und Blutbewegung

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

“…It was introduced in the 1950s by the German cardiologist Gerhart Liebau (1955a). 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). He found that rhythmic compression of this tube at asymmetric positions along its length generated unidirectional fluid flow, while compression at the point of symmetry (middle) did not generate unidirectional flow (Fig.…”

“…5;Liebau, 1955b). Based on these findings and on his textbook knowledge of the anatomy of the early embryonic heart, he speculated that the pumping function of the embryonic heart tube might be based on his newly discovered valveless pumping phenomenon (Liebau, 1955a(Liebau, ,b, 1968(Liebau, , 1970.…”

“…Furthermore, we should note that Liebau's research did not exclusively focus on physical pump models with only a single center of active compressions. He also reported on a few experiments in physical models with two, sequentially acting compression sites suggesting that the tubular hearts of higher vertebrate embryos may work as ''bi-'' or ''multi-segmental'' Liebau pumps (Liebau, 1955a(Liebau, , 1970. For unknown reasons, however, research on the Liebau effect has exclusively focused on mono-segmental pump models, while the bi-segmental models did not receive much recognition during the past 50 years.…”

Application of a Valveless Impedance Pump in a Liquid Cooling System

“…In his series of experiments [15][16][17][18], he used elastic tubes with different diameters and different elastic properties and demonstrated the occurrence of a valveless pumping effect. Therefore, the impedance-pumping phenomenon is sometimes referred to as Liebau phenomenon.…”