| FHS | fetal heart sound; fetal hydantoin syndrome; Floating Harbor syndrome |
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| FSS | focal segmental sclerosis; Freeman-Sheldon syndrome; French steel sound |
| Lp | lipoprotein; sound pressure level |
| LSD | laryngeal sound discrimination; least significant difference; least significant digit; low-sodium di... |
| LSV | lateral sacral vein; left subclavian vein; longitudinal sound velocity |
| 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) |
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| 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 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) |
| 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) |