Notice - Mark Hill
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Introduction
Before birth there are three identified "shunts" in the cardiovascular system:
- the foramen ovale, within the heart between the atria
- the ductus arteriosus, within the aortic arch
- the ductus venosus, within the liver
Some Recent Findings
- Prenatal cardiovascular shunts in amniotic vertebrates[1] "During amniotic vertebrate development, the embryo and fetus employ a number of cardiovascular shunts. These shunts provide a right-to-left shunt of blood and are essential components of embryonic life ensuring proper blood circulation to developing organs and fetal gas exchanger, as well as bypassing the pulmonary circuit and the unventilated, fluid filled lungs. In this review we examine and compare the embryonic shunts available for fetal mammals and embryonic reptiles, including lizards, crocodilians, and birds. These groups have either a single ductus arteriosus (mammals) or paired ductus arteriosi that provide a right-to-left shunt of right ventricular output away from the unventilated lungs. The mammalian foramen ovale and the avian atrial foramina function as a right-to-left shunt of blood between the atria. The presence of atrial shunts in non-avian reptiles is unknown. Mammals have a venous shunt, the ductus venosus that diverts umbilical venous return away from the liver and towards the inferior vena cava and foramen ovale. Reptiles do not have a ductus venosus during the latter two thirds of development. While the fetal shunts are well characterized in numerous mammalian species, much less is known about the developmental physiology of the reptilian embryonic shunts. In the last years, the reactivity and the process of closure of the ductus arteriosus have been characterized in the chicken and the emu. In contrast, much less is known about embryonic shunts in the non-avian reptiles. It is possible that the single ventricle found in lizards, snakes, and turtles and the origin of the left aorta in the crocodilians play a significant role in the right-to-left embryonic shunt in these species."
- Preferential streaming of the ductus venosus and inferior caval vein towards the right heart is associated with left heart underdevelopment in human fetuses with left-sided diaphragmatic hernia[2] "Left heart underdevelopment is commonly observed in fetuses with left diaphragmatic hernia. This finding has been attributed to compression of the left atrium by herniated abdominal organs, redistribution of fetal cardiac output and/or low pulmonary venous return. As preferential right or left heart underdevelopment is usually not a feature of right diaphragmatic hernia, we searched for an alternative mechanism. Since in normal fetuses the major fraction of left heart filling is provided by the ductus venosus via the inferior caval vein and oval foramen, our study focused in particular on the streaming direction of these structures."
|
Foramen Ovale
Ductus Arteriosus
Ductus Venosus
Textbooks
- Human Embryology (2nd ed.) Larson Ch7 p151-188 Heart
- The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Ch14: p304-349
- Before we Are Born (5th ed.) Moore and Persaud Ch12; p241-254
- Essentials of Human Embryology Larson Ch7 p97-122 Heart
- Human Embryology Fitzgerald and Fitzgerald Ch13-17: p77-111
Molecular
Abnormalities
References
- ↑ <pubmed>21513818</pubmed>
- ↑ <pubmed>20702536</pubmed>
Reviews
<pubmed>21513818</pubmed>
Articles
<pubmed>12589721</pubmed>
<pubmed>6832717</pubmed>
Search PubMed
Search Pubmed: heart valve development | cardiovascular shunts
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Cite this page: Hill, M.A. (2024, June 20) Embryology Cardiovascular System - Developmental Shunts. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Cardiovascular_System_-_Developmental_Shunts
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- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G