| LAA | left atrial appendage; left atrial area; leukemia-associated antigen; leukocyte ascorbic acid |
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| LAC | La Crosse [virus]; lactase; left atrial circumflex [artery]; left atrial contraction; linguoaxiocerv... |
| PAS | para aminosalicylate; Parent Attitude Scale; patient administration system; patient appointments and... |
| RAI | radioactive iodine; radioactive isotope; resident assessment instrument; resting ankle index; right ... |
| CLIP | Corticotropin-Like Intermediate Peptide |
| atrial granule serine proteinase | <enzyme> Converts pro-atrial natriuretic factor to anf by cleaving the arg98-ser99 bond; n-terminal 26-residue amino acid sequence given in first source Registry number: EC 3.4.21.- (26 Jun 1999) |
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| atrial myxoma | <cardiology, oncology, tumour> A very rare primary cardiac tumour, composed of connective tissue, located in the left or right atrium. Symptoms include chest pains, shortness of breath, orthopnoea, paroxysmal nocturnal dyspnoea, fainting, palpitations, dizziness and syncope. Diagnosis is confirmed by echocardiogram. Treatment involves the surgical excision of the tumour. (27 Sep 1997) |
| atrial natriuretic factor | <chemical> A potent natriuretic and vasodilatory peptide or mixture of different-sized low molecular weight peptides derived from a common precursor and secreted by the heart atria. All these peptides share a sequence of about 20 amino acids. Chemical name: Atriopeptin (12 Dec 1998) |
| atrial natriuretic peptide | <hormone> This cardiac hormone (28 amino acid residues) regulates salt and water balance in body fluids and blood pressure, it has potential as a medication to treat heart and kidney failure and the buildup of excess fluid in tissue. (09 Oct 1997) |
| 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) |
| 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 synchronous pulse generator | A ventricular stimulating pulse whose rate of discharge is directly determined by the atrial rate. Synonym: atrial triggered pulse generator. (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 triggered pulse generator | A ventricular stimulating pulse whose rate of discharge is directly determined by the atrial rate. Synonym: atrial triggered pulse generator. (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) |