The Driving Mechanism for Unidirectional Blood Flow in the Tubular Embryonic Heart.
The embryonic heart of vertebrate embryos, including humans, has a tubular thick-wall structure when it first starts to beat. The tubular embryonic heart (TEH) does not have valves, and yet, it produces an effective unidirectional blood flow. The actual pumping mechanism of the TEH is still controversial with pros and cons for either peristaltic pumping (PP) or impedance pumping (IP). On the other hand, observation of movies of the contractile TEH of the quail revealed a propagating wave from the venous end towards the arterial end that occludes the lumen behind the leading edge. This pattern of contraction represents a complex PP with a duty cycle, and was defined here as biological pumping (BP). In this work we developed a heart-like model that represents the main features of the chick TEH and allows for numerical analysis of all the three pumping mechanisms (i.e., IP, PP, and BP) as well as a comprehensive sensitivity evaluation of the structural, operating, and mechanical parameters. The physical model also included components representing the whole circulatory system of the TEH. The simulations results revealed that the BP mechanism yielded the level and time-dependent pattern of blood flow and blood pressure, as well as contractility that were observed in experiments.
Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, 69978, Tel Aviv, Israel. pavelko1@post.tau.ac.il.
Pavel
P
Kozlovsky
School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia.
Robert J
RJ
Bryson-Richardson
Ultrasound Unit in Obstetrics and Gynecology, Lis Maternity Hospital, Tel-Aviv Sourasky Medical Center, 64239, Tel Aviv, Israel.|Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.
Ariel J
AJ
Jaffa
School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, 69978, Tel Aviv, Israel.
Moshe
M
Rosenfeld
Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, 69978, Tel Aviv, Israel.
David
D
Elad
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D002642:Chick Embryo; D002645:Chickens; D006321:Heart / Q000196:embryology*; D006801:Humans; D008955:Models, Cardiovascular
Embryonic heart; Fluid–Structure Interaction; Impedance pumping; Peristaltic pumping; Valveless pumping