Pressure and flow in the umbilical cord |
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| Institution: | 1. School of Mathematical Sciences, The University of Adelaide, Australia;2. Department of Mathematics, Macquarie University, Australia;3. School of Medicine, The University of Adelaide, Australia;1. Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Tèc)cnico, Universidade de Lisboa, Lisboa, Portugal;2. Department of Mathematics and CEMAT, Instituto Superior Tèc)cnico, Universidade de Lisboa, Av. Rovisco Pais, No. 1, 1049-001 Lisboa, Portugal;1. Fetal Medicine Unit, St. George’s Hospital, London, United Kingdom;2. Chikitsa Diagnostic and Ultrasound Training Centre, 6,7 Mahinder Chambers, W T Patil Marg, Chembur, Mumbai, India;1. Women''s Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway and Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway;2. Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden;1. Faculty of Medical Science, State University of Piauí, Teresina, Piauí, Brazil;2. Postgraduate Animal Science Program, Federal University of Piauí, Teresina, Piauí, Brazil;3. Veterinary Medicine Undergraduate Course, Federal University of Piauí, Teresina, Piauí, Brazil;4. Federal Rural University of Pernambuco, Garanhuns, Pernambuco, Brazil;5. State University of Maranhão, São Luís, Maranhão, Brazil;6. Department of Veterinary Clinic and Surgery, Federal University of Piauí, Teresina, Piauí, Brazil;7. Department of Veterinary Morphophysiology, Federal University of Piauí, Teresina, Piauí, Brazil |
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| Abstract: | A fluid dynamic study of blood flow within the umbilical vessels of the human maternal-fetal circulatory system is considered. It is found that the umbilical coiling index (UCI) is unable to distinguish between cords of significantly varying pressure and flow characteristics, which are typically determined by the vessel curvature, torsion and length. Larger scale geometric non-uniformities superposed over the inherent coiling, including cords exhibiting width and/or local UCI variations as well as loose true knots, typically produce a small effect on the total pressure drop. Crucially, this implies that a helical geometry of mean coiling may be used to determine the steady vessel pressure drop through a more complex cord. The presence of vessel constriction, however, drastically increases the steady pressure drop and alters the flow profile. For pulsatile-flow within the arteries, the steady pressure approximates the time-averaged value with high accuracy over a wide range of cords. Furthermore, the relative peak systolic pressure measured over the period is virtually constant and approximately 25% below the equivalent straight-pipe value for a large range of non-straight vessels. Interestingly, this suggests that the presence of vessel helicity dampens extreme pressures within the arterial cycle and may provide another possible evolutionary benefit to the coiled structure of the cord. |
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| Keywords: | Umbilical cord UCI Blood flow Helical tube Computational fluid dynamics |
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