| ARC | accelerating rate calorimetry; acquired immunodeficiency syndrome-related complex; active renin conc... |
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| MAC | MacConkey [broth]; major ambulatory category; malignancy-associated changes; maximum allowable conce... |
| QRS | in electrocardiography, the complex consisting of Q, R, and S waves, corresponding to depolarization... |
| SFC | soluble fibrin complex; soluble fibrin-fibrinogen complex; spinal fluid count |
| APB | Atrial Premature Beat |
| atrial branches | The atrial branches, the branches of the right coronary artery and the circumflex branch of the left coronary artery distributed to the right and left atrium, respectively. Synonym: rami atriales. (05 Mar 2000) |
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| atrial capture beat | The cardiac cycle resulting when, after a period of A-V dissociation, the atria regain control of the ventricles; atrial depolarisation due to retrograde transmission from a ventricular ectopic beat or an electronically paced ventricular impulse. (05 Mar 2000) |
| atrial chaotic tachycardia | Multifocal origin of tachycardia within the atrium; often confused with atrial fibrillation during physical examination. (05 Mar 2000) |
| atrial diastole | Period of relaxation and repolarization of the atrial muscle. (05 Mar 2000) |
| atrial dipeptidyl carboxyhydrolase | <enzyme> Removes c-terminal phe-arg from atriopeptin II to give atriopeptin i; metalloenzyme with mw 240,000; also has tripeptidyl carboxyhydrolase activity; removes phe-arg-tyr from atriopeptin III to form atriopeptin i Registry number: EC 3.4.15.- (26 Jun 1999) |
| atrial dissociation | Mutually independent beating of the two atria or of parts of the atria. (05 Mar 2000) |
| atrial echo | Electrical reactivation of the atrium by a retrograde impulse returning from the A-V node while the antegrade impulse continues to the ventricle; characterised electrocardiographically, by a pair of P waves enclosing a QRS complex, the second P wave being inverted, indicating that it is the reverse (the retrograde pathway) of the pathway of the first P wave (the antegrade pathway). (05 Mar 2000) |
| atrial extrasystole | A premature contraction of the heart arising from an ectopic atrial focus. Synonym: auricular extrasystole. (05 Mar 2000) |
| atrial fibrillation | <cardiology> A condition where there is disorganised electrical conduction in the atria, resulting in ineffective pumping of blood into the ventricle. Acronym: AF (02 Jan 1998) |
| atrial flutter | <cardiology> A rapid well organised contraction of the atrium at a rate of 250-350 contractions per minute. Ventricular response rates are usually some multiple of 300. ECG shows sawtooth waves. Atrial flutter is considered a serious and potentially unstable rhythm. (27 Sep 1997) |
| atrial function | The haemodynamic and electrophysiological action of the atria. (12 Dec 1998) |
| atrial function, left | The haemodynamic and electrophysiological action of the left atrium. (12 Dec 1998) |
| atrial function, right | The haemodynamic and electrophysiological action of the right atrium. (12 Dec 1998) |
| atrial fusion beat | A beat that occurs when the atria are activated in part by the sinus impulse and in part by an ectopic or retrograde impulse from A-V junction or ventricle. (05 Mar 2000) |
| atrial gallop | Gallop rhythm in which the gallop sound follows atrial systole in late diastole and is an audible fourth heart sound due to forceful ventricular filling. Synonym: atrial gallop. Protodiastolic gallop, gallop rhythm in which the gallop sound occurs in early diastole and is an abnormal third heart sound. (05 Mar 2000) |