theta rhythm

rhythm (rithm) a measured movement; the recurrence of an action or function at regular intervals.rhyth´micrhyth´mical

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alpha rhythm  electroencephalographic waves having a uniform rhythm and average frequency of 10 per second, typical of a normal person awake in a quiet resting state.

atrial escape rhythm  a cardiac dysrhythmia occurring when sustained suppression of sinus impulse formation causes other atrial foci to act as cardiac pacemakers.

atrioventricular (AV) junctional rhythm  the heart rhythm that results when the atrioventricular junction acts as pacemaker.

atrioventricular (AV) junctional escape rhythm  a cardiac rhythm of four or more AV junctional escape beats at a rate below 60 beats per minute.

beta rhythm  electroencephalographic waves having a frequency of 18 to 30 per second, typical during periods of intense activity of the nervous system.

circadian rhythm  the regular recurrence in cycles of approximately 24 hours from one stated point to another, e.g., certain biological activities that occur at that interval regardless of constant darkness or other conditions of illumination.

coupled rhythm  heart beats occurring in pairs, the second beat usually being a ventricular premature beat; see also bigeminal pulse.

delta rhythm  rhythm on the electroencephalogram consisting of delta waves.

ectopic rhythm  a heart rhythm initiated by a focus outside the sinoatrial node.

escape rhythm  a heart rhythm initiated by lower centers when the sinoatrial node fails to initiate impulses, when its rhythmicity is depressed, or when its impulses are completely blocked.

gallop rhythm  an auscultatory finding of three (triple r.) or four (quadruple r.) heart sounds; the extra sounds occur in diastole and are related either to atrial contraction (S), to early rapid filling of a ventricle (S), or to concurrence of both events (summation gallop) .

idioventricular rhythm  a sustained series of impulses propagated by an independent pacemaker within the ventricles, with a rate of 20 to 50 beats per minute.

infradian rhythm  the regular recurrence in cycles of more than 24 hours, as certain biological activities which occur at such intervals, regardless of conditions of illumination.

nodal rhythm  atrioventricular junctional r.

pendulum rhythm  alternation in the rhythm of the heart sounds in which the diastolic and systolic sounds are nearly identical and the heartbeat resembles the tick of a watch.

quadruple rhythm  the gallop rhythm cadence produced when all four heart sounds recur in successive cardiac cycles.

reciprocal rhythm  a cardiac dysrhythmia established by a sustained reentrant mechanism in which impulses traveling back toward the atria also travel forward to reexcite the ventricles, so that each cycle contains a reciprocal beat, with two ventricular contractions.

reciprocating rhythm  a cardiac dysrhythmia in which an impulse initiated in the atrioventricular node travels toward both the atria and ventricles, followed by cycles of bidirectional propagation of the impulse alternately initiating from those impulses traveling up and those traveling down.

reentrant rhythm  an abnormal cardiac rhythm resulting from reentry.

sinoatrial rhythm , sinus rhythm the normal heart rhythm originating in the sinoatrial node.

supraventricular rhythm  any cardiac rhythm originating above the ventricles.

theta rhythm  rhythm on the electroencephalogram consisting of theta waves.

triple rhythm  the cadence produced when three heart sounds recur in successive cardiac cycles; see also gallop r.

ultradian rhythm  the regular recurrence in cycles of less than 24 hours, as certain biological activities which occur at such intervals, regardless of conditions of illumination.

ventricular rhythm 

1. idioventricular r.

2. any cardiac rhythm controlled by a focus within the ventricles.

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theta rhythm

a rhythmic hippocampal electrical discharge correlated with movement and locomotion.