| AOS | American Ophthalmological Society; American Otological Society; anodal opening sound; anterior [o]es... |
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| AOT | accessory optic tract; Anderson Olsson table; anodal opening tetanus; Association of Occupational Th... |
| AOTe | anodal opening tetanus |
| CaOC | cathodal opening contraction |
| CaOCL | cathodal opening clonus |
| aortic body tumour | Aortic body, carotid body, chemoreceptor, or glomus jugulare tumour; nonchromaffin paraganglioma; receptoma; a relatively rare, usually benign neoplasm originating in the chemoreceptor tissue of the carotid body, glomus jugulare, and aortic bodies; consisting histologically of rounded or ovoid hyperchromatic cells that tend to be grouped in an alveolus-like pattern within a scant to moderate amount of fibrous stroma and a few large thin-walled vascular channels. Compare: paraganglioma. Synonym: aortic body tumour, carotid body tumour, chemoreceptor tumour, glomus jugulare tumour, nonchromaffin paraganglioma. Origin: chemo-+ G. Dektes, receiver, fr. Dechomai, to receive, + -oma, tumour (05 Mar 2000) |
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| aortic bulb | The dilated first part of the aorta containing the aortic semilunar valves and the aortic sinuses. Synonym: bulbus aortae, arterial bulb. (05 Mar 2000) |
| aortic coarctation | <radiology> most frequent cause of PVH and congestive heart failure in 2nd and 3rd weeks of life associated with, bicuspid aortic valve (50-80%), calcific aortic stenosis (due to bicuspid valve), patent ductus arteriosus or VSD (in most) see also: abdominal aortic coarctation (12 Dec 1998) |
| aortic curtain | An intertrigonal sheet of fibrous tissue between the aortic annulus and the anterior leaflet of the mitral valve. (05 Mar 2000) |
| aortic dissection | A pathologic process, characterised by splitting of the media layer of the aorta, which leads to formation of a dissecting aneurysm. Classified according to location as follows: type I involves the ascending aorta, transverse arch, and distal aorta; type II is confined to the ascending aorta; type III extends distally in the descending aorta. (05 Mar 2000) |
| aortic dissection: aetiology | <radiology> Usually degenerative, due to aging, increased risk: hypertension, bicuspic aortic valve, aortic coarctation, pregnancy, connective tissue disorder (Marfan, Ehlers-Danlos), skeletal abnormalities (scoliosis, pectus), mycotic aneurysm, Takayasu (giant cell) arteritis, aortic laceration see also: classification (12 Dec 1998) |
| aortic dissection: classification | <radiology> DeBakey: I ascending aorta to arch with or without descending aorta (30%), II ascending aorta only (20%), III descending aorta to thoracic aorta (50%), Stanford: A involvement of ascending aorta (regardless of origin), B aortic arch and distal aorta see also: aetiology mnemomics: 1 A.D. (DeBakey), A = Ascending (12 Dec 1998) |
| aortic dwarfism | Underdevelopment of physical stature associated with severe aortic stenosis. (05 Mar 2000) |
| aortic facies | The pale sallow complexion of one suffering from incompetence of the aortic valve. (05 Mar 2000) |
| aortic foramen | The opening in the diaphragm bounded by the two crura, the vertebral column, and the median arcuate ligament, through which pass the aorta and thoracic duct. Synonym: hiatus aorticus, aortic foramen, aortic opening. (05 Mar 2000) |
| aortic hiatus | The opening in the diaphragm bounded by the two crura, the vertebral column, and the median arcuate ligament, through which pass the aorta and thoracic duct. Synonym: hiatus aorticus, aortic foramen, aortic opening. (05 Mar 2000) |
| aortic incompetence | Defective closure of the aortic valve permitting regurgitation into the left ventricle during diastole. (05 Mar 2000) |
| aortic insufficiency | A congenital or acquired heart valve abnormality that results in the abnormal back flow of blood in the aorta, through an incompetent aortic valve and into the left ventricle. Chronic aortic insufficiency leads to enlargement of the left ventricle and pulmonary congestion. If left uncorrected, congestive heart failure will result. Aortic valve replacement is eventually necessary in most cases of significant valvular incompetence. (27 Sep 1997) |
| aortic knob | The prominent shadow of the aortic arch on a frontal chest radiograph. (05 Mar 2000) |
| aortic knuckle | The contour of the aortic arch protruding from the mediastinal silhouette in an anteroposterior (AP) radiograph of the chest. (05 Mar 2000) |