| AP | accessory pathway; accounts payable; acid phosphatase; acinar parenchyma; action potential; active p... |
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| LAP | laparoscopy; laparotomy; left arterial pressure; left atrial pressure; leucine aminopeptidase; leuke... |
| AAT | Aachen Aphasia Test; academic aptitude test; alanine aminotransferase; alkylating agent therapy; alp... |
| AS | acetylstrophanthidin; acidified serum; acoustic schwannoma; acoustic stimulation; active sarcoidosis... |
| LAA | left atrial appendage; left atrial area; leukemia-associated antigen; leukocyte ascorbic acid |
| atrial premature complexes | Premature contractions of the heart arising from an ectopic atrial focus. With ventricular premature complexes, they represent one of the most common causes of irregular pulse. They are more apt to occur if there is atrial or conduction system disease such as left atrial enlargement in mitral stenosis. In community prospective studies, atrial premature complexes are not related to sudden death, as are ventricular premature beats in coronary disease. (12 Dec 1998) |
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| atrial premature contraction | <cardiology> An premature heartbeat of atrial origin. Generally nonserious and typically exacerbated by stimulant use (for example alcohol, decongestants, caffeine, nicotine). (27 Sep 1997) |
| atrial septal defect | <cardiology> An inherited condition where there is nonclosure of the foramen ovale at birth, resulting in congenital heart disease. Usually asymptomatic until the third or fourth decades of life. Symptoms include exertional shortness of breath, fatigue and palpitations. Acronym: ASD (12 Jan 1998) |
| atrial septum | The wall between the two upper chambers (the right and left atrium) of the heart. (12 Dec 1998) |
| atrial sound | The sound produced in late diastole in association with ventricular filling due to atrial systole and related to reduced ventricular compliance. It is a low frequency oscillation that may be normal at older ages owing to a physiologic decline in ventricular compliance but is nearly always abnormal at younger ages if it is of high intensity or palpable. It is common in ventricular hypertrophy, particularly with hypertension, and is almost invariable during acute myocardial infarction. Fourth heart sounds may arise from the right or left ventricle or both. Synonym: atrial sound. (05 Mar 2000) |
| atrial systole | Contraction of the atria. Synonym: auricular systole. (05 Mar 2000) |
| atrial tachycardia | Paroxysmal tachycardia originating in an ectopic focus in the atrium. Synonym: auricular tachycardia. (05 Mar 2000) |
| atrial transport function | The role of the atria in filling and stretching the ventricles by their presystolic contraction, without which the force of ventricular contraction and hence the cardiac output may significantly decrease. (05 Mar 2000) |
| atrial ventricular canal defect | A defect caused by deficient or absent septal tissue immediately above and below the normal level of the atrioventricular valves, including the region normally occupied by the A-V septum in hearts with two ventricles. The A-V valves are abnormal to a varying degree. (05 Mar 2000) |
| atrial-well technique | An obsolete semi-closed surgical technique for repairing atrial septal defects and other cardiac abnormalities. (05 Mar 2000) |
| receptors, atrial natriuretic factor | Cell surface proteins that bind atrial natriuretic factor with high affinity and trigger intracellular changes influencing the behaviour of cells. (12 Dec 1998) |
| paroxysmal atrial tachycardia | Bouts of rapid, regular heart beating originating in the atrium (upper chamber of the heart). Due to abnormalities in the av node relay station that lead to rapid firing of electrical impulses from the atrium which bypass the av node under certain conditions. These conditions include alcohol excess, stress, caffeine, overactive thyroid or excessive thyroid hormone intake, and certain drugs. Pat is an example of an arrhythmia where the abnormality is in the electrical system of the heart, while the heart muscle and valves may be normal. (12 Dec 1998) |
| medial atrial vein | A vein that drains deep portions of the parietal and occipital lobes; it runs in the medial wall of the lateral ventricle to empty into the internal cerebral vein or the great cerebral vein. Synonym: vena ventriculi lateralis medialis, medial atrial vein, medial vein of lateral ventricle. (05 Mar 2000) |
| multifocal atrial tachycardia | A rapid heart rate that is generated from multiple locations within the atria. Multifocal atrial tachycardia (MAT) tends to be in the range of 100 to 180 beats per minute. MAT can be seen in association with COPD, pneumonia, CHF, lung cancer, diabetes, pulmonary embolism, theophylline toxicity, coronary artery disease or digoxin toxicity. Origin: Gr. Kardia = heart (27 Sep 1997) |
| heart septal defects, atrial | Defects in the septum between the atria of the heart, due to failure of fusion between either the septum secundum or the septum primum and the endocardial cushions. (12 Dec 1998) |