Valveless Pumping in Biology and Medicine

Dear Colleagues,

Journal of Cardiovascular Development and Disease (JCDD) is launching a Special Issue on valveless pumping in biology and medicine. Our lives, as well as the function of several machines and technical systems (e.g., heating systems, pipelines), depend on the action of pumps generating unidirectional fluid flow. Based on the presence of structural elements that regulate the flow direction (valves), biological as well as technical pumping systems can be assigned to one of two different pump categories: (1) those supported by valves (valve-based pumping), and (2) those lacking valves (valveless pumping). Our perception of the generation of unidirectional fluid flow in the conduits of the cardiovascular and lymphatic systems of human beings is dominated by the action of valve-based pumps, such as the four-chambered heart and the valve-bearing segments of veins and lymphatic vessels. Proper function of these pumps is known to depend on the condition of the valves, as demonstrated by the well-known pathophysiological consequences of valve insufficiency. We therefore rarely consider the possibility that valveless pumping mechanisms may make functionally important contributions to the generation of blood or lymph flow. Biological systems use a great variety of valveless pumping mechanisms, but most of us are familiar with only two different valveless pumping phenomena: (1) the cilia-driven fluid transport in the respiratory system and the fallopian tube; and (2) the mechanism of propulsive peristalsis, which is usually attributed to the fluid transport in the gastrointestinal and urogenital systems. Other valveless pumping phenomena, such as the so-called Liebau effect, are known only by a relatively small group of researchers, although some of these phenomena seem to play important roles in the dynamics of our body fluids.

The goals of this Special Issue are (1) to stimulate, in a broad readership, the interest in valveless pumping phenomena; and (2) to inspire new thinkings and new investigations on the physiology and pathophysiology of fluid transport within our body. Valveless pumping phenomena stand at the base of the phylogeny and ontogeny of our cardiovascular system: the blood flow in the common ancestor of the chordate phylum (which includes cephalochordates, urochordates, and vertebrates) was probably generated by a central tubular heart that used a valveless pumping mechanism. Such a valveless heart, which is homologous to the central heart of vertebrates, is found in today’s urochordates such as Ciona intestinalis. Urochordates represent the sister group of vertebrates, and the heart of Ciona intestinalis has a long history as a model in cardiovascular research. The embryonic heart of humans and other vertebrates also has a tubular shape, and also acts as a valveless pump during the initial phase of its pumping activity. Valveless pumping phenomena seem to work not only during the embryogenesis of our cardiovascular system. They also seem to contribute to the physiological and pathophysiological fluid dynamics in the mature cardiovascular and lymphatic systems as well as in the circulation of the cerebrospinal fluid. Moreover, valveless pumps are promising candidates for biomedical applications, such as implantable drug delivery systems.

This Special Issue will provide a platform for the presentation of our current knowledge on valveless pumping phenomena, their roles in the physiology and pathophysiology of fluid transport within the body of humans and animals, as well as their current and prospective use in biomedical applications.

Prof. Dr. Jörg Männer
Guest Editor

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• valveless pumping
• liebau effect
• peristalsis
• transport of body fluids
• developmental physiology of the cardiovascular system