| atrial auricula | A small conical ("ear-shaped") pouch projecting from the upper anterior portion of each atrium of the heart, increasing slightly the atrial volume. See: auricle of left atrium, auricle of right atrium. Synonym: auricula atrialis, atrial auricle, atrial auricula, auricle, auricula, auricular appendage, auricular appendix, skin tag. (05 Mar 2000) |
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| atrial bigeminy | Pairing of atrial beats, as when an atrial extrasystole is coupled to each sinus beat. (05 Mar 2000) |
| 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) |
| 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 complex | P wave in the electrocardiogram. Synonym: auricular complex. (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 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) |