| 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) |
| 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) |
| 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) |