| AH | abdominal hysterectomy; absorptive hypercalciuria; accidental hypothermia; acetohexamide; acid hydro... |
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| ALVAD | abdominal left ventricular assist device |
| A/P | abdominal/perineal; antepartum; ascites/plasma [ratio] |
| AT | abdominal thrusts; achievement test; Achilles tendon; Achard-Thiers [syndrome]; adaptive thermogenes... |
| ATI | abdominal trauma index |
| aortic | Relating to the aorta or the aortic orifice of the left ventricle of the heart. Synonym: aortal. (05 Mar 2000) |
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| aortic aneurysm | Dangeous ballooning of the aorta (the main artery leaving the heart) which is caused by disease in the artery's wall. (09 Oct 1997) |
| aortic aneurysm, thoracic | An aneurysm in the proximal portion of the descending aorta proceeding from the arch of the aorta and giving rise to the bronchial, oesophageal, pericardiac, and mediastinal branches. (12 Dec 1998) |
| aortic arch | The curved portion between the ascending and descending parts of the aorta; it begins as a continuation of the ascending aorta posterior to the sternal angle, runs posteriorly and slightly to the left as it passes over the root of the left lung, and becomes the descending aorta as it reaches and begins to course along the vertebral column; it gives rise to the brachiocephalic trunk, the left common carotid and left subclavian arteries. Any member of the several pairs of arterial channels encircling the embryonic pharynx in the mesenchyme of the brachial arches; there are potentially six pairs, but in mammals the fifth pair is poorly developed or absent. The first and second pairs are functional only in very young embryos; the third pair is involved in the formation of the carotids; the fourth arch on the left is incorporated in the arch of the aorta; the sixth pair forms the proximal part of the pulmonary arteries. A series of arterial channels encircling the embryonic pharynx in the mesenchyme of the branchial arch's. There are potentially six pairs, but in mammals the fifth pair is poorly developed or absent. The first and second pairs are functional only in very young embryos; the third pair is involved in the formation of the carotids; the fourth arch on the left is incorporated in the arch of the aorta; the sixth pair forms the proximal part of the pulmonary arteries. Synonym: arcus aortae. (05 Mar 2000) |
| aortic arch syndrome | <syndrome> Aortic arch syndrome, also referred to by many as vertebral-basilar artery disease, carotid artery occlusive syndrome and subclavian steal syndrome is characterised by a constellation of signs and symptoms which occur secondary to abnormalities in the major arteries which extend off of the aortic arch. These abnormalities are structural and most often secondary to the effects of atherosclerosis, blood clots, trauma or a congenital abnormality. Symptoms of this condition include various neurologic symptoms, reduction in pulse and changes in blood pressure. (27 Sep 1997) |
| aortic arch syndromes | Any of a group of disorders leading to occlusion of the arteries arising from the aortic arch. Such occlusion may be caused by atherosclerosis, arterial embolism, syphilitic or tuberculous arteritis, etc. (12 Dec 1998) |
| aortic area | The region of the chest wall over the second right costal cartilage, where sounds produced at the aortic orifice are often best heard. (05 Mar 2000) |
| aortic atresia | Congenital absence of the normal valvular orifice into the aorta. (05 Mar 2000) |
| aortic bodies | Small clusters of chemoreceptive and supporting cells located near the aortic arch, the pulmonary arteries, and the coronary arteries. The aortic bodies sense pH, carbon dioxide, and oxygen concentrations in the blood and participate in the control of respiration. (12 Dec 1998) |
| 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) |
| 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) |