rhythm (redirected from sinoatrial 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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rhythm (rm)

n.

Movement or variation characterized by the regular recurrence or alternation of different quantities or conditions, as in the heartbeat.

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rhythm,

n recurring pattern of waves, vibrations, or sounds.

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rhythm (rith´m),

n a measured movement; the recurrence of an action or function at regular intervals.

rhythm, heart,

n the rhythm pattern in the sequence of heart beats, which may be altered in the presence of cardiac disease.

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rhythm

a measured movement; the recurrence of an action or function at regular intervals.

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alpha rhythm

a uniform rhythm of waves in the normal electroencephalogram.

beta rhythm

a rhythm in the electroencephalogram consisting of waves smaller than those of the alpha rhythm, having an average frequency of 25 per second, typical during periods of intense activity of the nervous system. See also electroencephalography.

biological r's

the cyclic changes that occur in physiological processes of living organisms; called also biorhythms. These rhythms are so persistent throughout the living kingdom that they probably should be considered a fundamental characteristic of life, as are growth, reproduction, metabolism and irritability. Many of the physiological rhythms occur in animals about every 24 hours (circadian rhythm). Examples include the peaks and troughs that are manifested in body temperature, vital signs, brain function and muscular activity. Biochemical analyses of urine, blood enzymes and plasma serum also have demonstrated rhythmic fluctuations in a 24-hour period.

It has long been believed that the cyclic changes observed in plants and animals were totally in response to environmental changes and, as such, were exogenous or of external origin. This hypothesis is now being rejected by some chronobiologists who hold that the biological rhythms are intrinsic to the organisms, and that the organisms possess their own physiological mechanism for keeping time. This mechanism has been called the 'biological clock'.

circadian rhythm

see circadian rhythm.

circamensual rhythm

that which occurs in cycles of about one month (30 days).

circannual rhythm

the recurrence of a phenomenon in cycles of about one year.

circaseptan rhythm

that which occurs in cycles of about 7 days (one week).

coupled rhythm

heartbeats occurring in pairs, the second beat of the pair usually being a ventricular premature beat.

escape rhythm

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

gallop rhythm

an auscultatory finding of three or four heart sounds, the extra sounds by convention being in diastole and related to atrial contraction (fourth sound, presystolic gallop), to early rapid filling of a ventricle with an altered ventricular compliance (protodiastolic gallop), or to concurrence of atrial contraction and ventricular early rapid filling (summation gallop).

idioventricular rhythm

a series of ventricular escape complexes occuring at a regular rate.

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

heart rhythm initiated in the specialized junctional tissue, i.e. the atrioventricular node and the main (His) bundle.

nyctohemeral rhythm

a day and night rhythm.

pendulum rhythm

alternation in the rhythm of the heart sounds in which the diastolic sound is equal in time, character and loudness to the systolic sound, the beat of the heart resembling the tick of a watch.

sinus rhythm

normal heart rhythm originating in the sinoatrial node.

Electrocardiogram showing normal sinus rhythm in a dog. By permission from Darke P, Kelly DF, Bonagura JD, Color Atlas of Veterinary Cardiology, Mosby, 1995

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

the ventricular contractions which occur in cases of complete heart block.