| quadruple rhythm | A quadruple cadence to the heart sounds due to the easy audibility of both third and fourth heart sounds, indicative of serious myocardial disease. Synonym: trainwheel rhythm. (05 Mar 2000) |
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| theta rhythm | Brain waves in the electroencephalogram which have a frequency of 4 to 7 per second. They occur mainly in children but also in adults during periods of emotional stress. (12 Dec 1998) |
| ectopic rhythm | Any cardiac rhythm arising from a centre other than the normal pacemaker, the sinus node. (05 Mar 2000) |
| tic-tac rhythm | A condition in which the cadence of the heart sounds resembles that of the foetus, the first and second sounds becoming alike and evenly spaced; a sign of serious myocardial disease. Synonym: pendulum rhythm, tic-tac rhythm, tic-tac sounds. Origin: embryo-+ G. Kardia, heart (05 Mar 2000) |
| trainwheel rhythm | A quadruple cadence to the heart sounds due to the easy audibility of both third and fourth heart sounds, indicative of serious myocardial disease. Synonym: trainwheel rhythm. (05 Mar 2000) |
| trigeminal rhythm | A cardiac arrhythmia in which the beats are grouped in trios, usually composed of a sinus beat followed by two extrasystoles. Synonym: trigeminy. (05 Mar 2000) |
| triple rhythm | A triple cadence to the heart sounds at any heart rate, due to the easy audibility of a third (usually) or fourth heart sound, or at faster rates a summation sound due to coincidence of the third and fourth heart sounds. (05 Mar 2000) |
| junctional rhythm | Rhythms originating anywhere within the A-V junction. Formerly, "A-V nodal" or simply "nodal" rhythms. (05 Mar 2000) |
| ultradian rhythm | See: ultradian. (05 Mar 2000) |
| arrhythmias, atrial | Abnormal heart rhythm due to electrical disturbances in the atria (the upper chambers of the heart) or the AV node relay station , leading to fast heart beats. Examples of atrial arrhythmias includes atrial fibrillation, atrial flutter, and paroxysmal atrial tachycardia (PAT). (12 Dec 1998) |
| atrial | <anatomy> Pertaining to an atrium. (16 Dec 1997) |
| atrial appendage | The small projection from each atrium hanging over like a small ear, more marked on the left, with a small cavity of its own. (05 Mar 2000) |
| atrial arrhythmias | See Arrhythmias, atrial. (12 Dec 1998) |
| atrial arteries | Branches of the right and left coronary arteries distributed to the muscle of the atria. Synonym: arteriae atriales. (05 Mar 2000) |
| atrial auricle | The auricle of atrium. See: left atrium, right atrium. (05 Mar 2000) |