| AI | accidental injury; accidentally incurred; adiposity index; aggregation index; allergy and immunology... |
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| AS | acetylstrophanthidin; acidified serum; acoustic schwannoma; acoustic stimulation; active sarcoidosis... |
| AVA | activity vector analysis; antiviral antibody; aortic valve area; aortic valve atresia; arteriovenous... |
| AVO | aortic valve opening; aortic valve orifice; atrioventricular opening |
| SAR | scatter/air ratio; seasonal allergic rhinitis; sexual attitude reassessment; slowly adapting recepto... |
| aortic orifice | The opening from the left ventricle into the ascending aorta; it is guarded by the aortic valve. Synonym: ostium aortae, aortic ostium. (05 Mar 2000) |
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| aortic ostium | The opening from the left ventricle into the ascending aorta; it is guarded by the aortic valve. Synonym: ostium aortae, aortic ostium. (05 Mar 2000) |
| aortic pseudo-coarctation | <radiology> Aortic kinking, rare congenital anomaly of aortic arch, long, redundant thoracic aorta, 3-sign, associated with aortic valve abnormalities (bicuspid valve, AI, AS), can develop aneurysms, no haemodynamic obstruction, no congenital heart disease Cf: coarctation (12 Dec 1998) |
| aortic-pulmonic window | The indentation of the left side of the mediastinum by the lung partially interposed between the aortic arch and the left pulmonary artery, seen on frontal radiographs of the chest. Synonym: aortic-pulmonic window. (05 Mar 2000) |
| aortic reflex | A fall in blood pressure due to peripheral vasodilation and cardiac inhibition by stimulations of terminations of a cardiac depressor nerve in the aortic arch and base of the heart. Synonym: aortic reflex, depressor reflex. (05 Mar 2000) |
| aortic regurgitation | 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 regurgitation: aetiology | <radiology> INTRINSIC VALVE DISEASE, congenital bicuspid valve, rheumatic endocarditis, bacterial endocarditis (perforation / prolapse of cusp), myxomatous valve associated with cystic medial necrosis, prosthetic valve: mechanical break, thrombosis, paravalvular leak PRIMARY DISEASE OF ASCENDING AORTA, dilatation of the aortic annulus, syphilitic aortitis, ankylosing spondylitis (5-10%), Reiter disease, rheumatoid arthritis, cystic medial necrosis: Marfan syndrome, laceration, decelerating trauma; hypertension see: aortic regurgitation (12 Dec 1998) |
| aortic rupture | Tearing of aortic tissue. It may be rupture of an aneurysm or it may be due to trauma. (12 Dec 1998) |
| aortic sac | In mammalian embryos, the endothelially lined dilation just distal to the truncus arteriosus; it is the primordial vascular channel from which the aortic arches arise and is homologous to the ventral aorta of gill-bearing vertebrates. (05 Mar 2000) |
| aortic septal defect | A small congenital opening between the aorta and pulmonary artery about 1 cm above the semilunar valves, e.g., aorticopulmonary window. Synonym: aorticopulmonary window. (05 Mar 2000) |
| aortic sinus | The space between the superior aspect of each cusp of the aortic valve and the dilated portion of the wall of the ascending aorta, immediately above each cusp. Synonym: sinus aortae, Petit's sinus, Valsalva's sinus. Arlt's sinus, an inconstant depression on the lower portion of the internal surface of the lacrimal sac. Barber's pilonidal sinus, pilonidal sinus occurring in barbers, usually in the web between the fingers, due to the burying of exogenous hairs by the alternate loosening and tightening of tissues of the hand by the manipulation of scissors. (05 Mar 2000) |
| aortic sinus aneurysm | Abnormal dilation of one or more of the three aortic sinuses situated behind the three aortic valve cusps. (05 Mar 2000) |
| aortic spindle | A fusiform dilation of the aorta immediately beyond the isthmus. Synonym: His' spindle. (05 Mar 2000) |
| aortic stenosis | Progressive narrowing of the aortic valve resulting in the obstructed passage of blood from the left ventricle into the aorta. Causes for aortic stenosis include rheumatic fever, congenital and idiopathic sclerosis. Chronic stenosis can lead to left ventricular enlargement and congestive heart failure. (27 Sep 1997) |
| aortic sulcus | A broad deep groove on the medial aspect of the left lung above and behind the hilum receiving the arch of the aorta and the thoracic aorta. Synonym: sulcus aorticus. (05 Mar 2000) |