Situs ambiguus is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen. Clinically heterotaxy spectrum generally refers to any defect of Left-right asymmetry and arrangement of the visceral organs; however, classical heterotaxy requires multiple organs to be affected. This does not include the congenital defect situs inversus,[1] which results when arrangement of all the organs in the abdomen and chest are mirrored, so the positions are opposite the normal placement. Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs. Situs ambiguus can also be subdivided into left-isomerism and right isomerism based on the defects observed in the spleen, lungs and atria of the heart.
Individuals with situs inversus or situs solitus do not experience fatal dysfunction of their organ systems, as general anatomy and morphology of the abdominothoracic organ-vessel systems are conserved. Due to abnormal arrangement of organs in situs ambiguus, orientation across the left-right axis of the body is disrupted early in fetal development, resulting in severely flawed cardiac development and function in 50–80% of cases. They also experience complications with systemic and pulmonary blood vessels, significant morbidity, and sometimes death.[2] All patients with situs ambiguus lack lateralization and symmetry of organs in the abdominal and thoracic cavities and are clinically considered to have a form of heterotaxy syndrome.
Heterotaxy syndrome with atrial isomerism occurs in 1 out of every 10,000 live births and is associated with approximately 3% of congenital heart disease cases.[3] Additional estimation of incidence and prevalence of isomerism proves difficult due to failure to diagnose and underestimation of the disease by clinicians. Furthermore, right isomerism is much more easily recognized than left isomerism, contributing to the failure to diagnose.[4]
Situs ambiguus is a growing field of research with findings dating back to 1973.[5]
^"heterotaxy syndrome". United States National Library of Medicine. Retrieved 23 May 2016.
^Lowenthal, A.; et al. (September 26, 2015). "Anatomy, clinical manifestations and diagnosis of heterotaxy (isomerism of the atrial appendages)". Up To Date. Retrieved November 4, 2015.
^Zhu, Lirong; Belmont, John W.; Ware, Stephanie M. (2005-10-26). "Genetics of human heterotaxias". European Journal of Human Genetics. 14 (1): 17–25. doi:10.1038/sj.ejhg.5201506. ISSN 1018-4813. PMID 16251896.
^Cite error: The named reference :1 was invoked but never defined (see the help page).
^Freedom, Robert M.; Treves, S. (1973-05-01). "Splenic Scintigraphy and Radionuclide Venography in the Heterotaxy Syndrome". Radiology. 107 (2): 381–386. doi:10.1148/107.2.381. ISSN 0033-8419. PMID 4695908.
Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs. Situsambiguus can...
isolated dextrocardia)[citation needed] and dextrocardia situs inversus. Dextrocardia situs inversus is further divided. In this form of dextrocardia...
Situs inversus (also called situs transversus or oppositus) is a congenital condition in which the major visceral organs are reversed or mirrored from...
reversal of all organs is known as situs inversus, while reversal of some organs but not others is called situsambiguus or heterotaxy. Isolated reversal...
condition called situsambiguus or heterotaxy, where organ placement or development is neither typical (situs solitus) nor totally reversed (situs inversus totalis)...
inverted disposition of organs Situsambiguus (heterotaxia), comprises mixed cases where only some organs are inverted Situ (office), a high-ranking government...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
malrotation, situs inversus, biliary atresia, and several cardiac malformations. Associated cardiac conditions include dextrocardia, atrial situsambiguus, ventricular...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
visceral organs, which can be in situs solitus, where the remainder of the organs are on normal side as well; or situs inversus, in which the viscera (stomach...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
Handedness Inventory Geschwind–Galaburda hypothesis Neuroanatomy of handedness Situs inversus Twins and handedness Podestá, María Mercedes; Raffino, Rodolfo...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
causing the misplacement of her internal organs. The condition, a form of situsambiguus, is exceptionally rare and has an occurrence of one in 60 million; only...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
anatomic abnormalities such as situs inversus (a combination of findings is known as Kartagener syndrome), and situsambiguus (also known as Heterotaxy syndrome)...
in the ants' compound eyes (differential ommatidia count). Dextrocardia Situs inversus Ellis, S. J.; Ellis, P. J.; Marshall, E.; Joses, S. (1998). "Is...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
LRRTM1 In heart Levocardia Dextrocardia In major viscera Situs solitus SitusambiguusSitus inversus In feet Footedness Footedness in boardsports Regular...
from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The vagus was also historically called the pneumogastric nerve. Upon leaving...
originates from the nucleus ambiguus in the reticular formation of the rostral medulla. Fibers leaving the nucleus ambiguus travel anteriorly and laterally...
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