| idiojunctional rhythm | An independent rhythm, the ventricles being under control of the A-V node (A-V junction). Synonym: idiojunctional rhythm. (05 Mar 2000) |
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| idionodal rhythm | An independent rhythm, the ventricles being under control of the A-V node (A-V junction). Synonym: idiojunctional rhythm. (05 Mar 2000) |
| idioventricular rhythm | A slow independent ventricular rhythm under control of a ventricular centre (which is, by definition, ectopic). Synonym: ventricular rhythm. (05 Mar 2000) |
| quadrigeminal rhythm | A cardiac arrhythmia in which the heartbeats are grouped in fours, each usually composed of one sinus beat followed by three extrasystoles, but a repetitive group of four of any composition is quadrigeminal. Synonym: quadrigeminy. (05 Mar 2000) |
| 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) |
| 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) |
| escape rhythm | Three or more consecutive impulses at a rate not exceeding the upper limit of the inherent pacemaker; extreme range of impulse formation at the sinoatrial node is between 40 to 180 impulses per minute, that of the atrioventricular junction is normally 40 to 60 impulses per minute, and the normal rate of the ventricular myocardium (idioventricular rhythm) is 20 to 40 impulses per minute. (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) |
| Galton's delta | A more or less well-marked triangle, in a fingerprint, on either side where the straight ridges near the joint of the distal phalanx are succeeded by arches, loops, or whorls. See: Galton's system of classification of fingerprints. Synonym: triradius. (05 Mar 2000) |