An automatic tachycardia is a
cardiac arrhythmia
Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
which involves an area of the heart generating an abnormally fast rhythm, sometimes also called enhanced automaticity. These tachycardias, or fast heart rhythms, differ from reentrant tachycardias (
AVRT and
AVNRT) in which there is an abnormal electrical pathway which gives rise to the pathology. Most automatic tachycardias are
supraventricular tachycardias (SVT). It is important to recognise an automatic tachycardia because the treatment will be different to that for a reentrant tachycardia. The most useful clue will be the presence of 'warm up' and 'cool down'. This means that whereas a reentrant tachycardia will both begin and end abruptly as cardiac conduction utilises then ceases to utilise the accessory pathway, an automatic tachycardia will rise and fall gradually in rate as the automatic focus increases and decreases its automatic rate of electrical discharge.
[Lister B et al. Paediatric BASIC: Basic Assessment and Support in Paediatric Intensive Care. Department of Anaesthesia and Intensive Care of The Chinese University of Hong Kong, Hong Kong 2016.]
Types
The different types are the following:
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Sinus tachycardia
Sinus tachycardia is an elevated sinus rhythm characterized by an increase in the rate of electrical impulses arising from the sinoatrial node. In adults, sinus tachycardia is defined as a heart rate greater than 100 beats per minute (bpm). The ...
may be considered an automatic tachycardia, since the
sinoatrial node
The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approxima ...
(SAN) is discharging at an abnormally fast rate.
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Atrial ectopic tachycardia, in which the focus or foci are in the atria of the heart, is an automatic tachycardia.
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Atrial fibrillation may be considered an automatic tachycardia.
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Junctional ectopic tachycardia
Junctional ectopic tachycardia (JET) is a rare syndrome of the heart that manifests in patients recovering from heart surgery. It is characterized by cardiac arrhythmia, or irregular beating of the heart, caused by abnormal conduction from or thr ...
, in which the focus is in the
atrioventricular node
The atrioventricular node or AV node electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of t ...
(AVN), and
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Accelerated idioventricular rhythm
Accelerated idioventricular rhythm is a ventricular rhythm with a rate of between 40 and 120 beats per minute. Idioventricular means “relating to or affecting the cardiac ventricle alone” and refers to any ectopic ventricular arrhythmia. Accel ...
, involving a
ventricular focus, are also examples. Idioventricular tachycardia is notable because it is the only automatic tachycardia which is not an SVT.
Treatment
Treatment depends on the origin of the automatic tachycardia, however the mainstay of treatment is either
antidysrhythmic medication or
cardiac pacing
An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart eith ...
. Specifically
overdrive pacing may be used for all forms of automatic tachycardia; a pacemaker assumes control of the heart rhythm in overdrive pacing. In some cases
ablation
Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft material for a ...
of the ectopic focus may be necessary.
See also
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Cardiac ectopy
Ectopic beat is a disturbance of the cardiac rhythm frequently related to the electrical conduction system of the heart, in which beats arise from fibers or group of fibers outside the region in the heart muscle ordinarily responsible for impulse ...
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Clinical cardiac electrophysiology {{unreferenced, date=February 2009
Clinical cardiac electrophysiology (also referred to as cardiac electrophysiology, arrhythmia services, or electrophysiology), is a branch of the medical specialty of cardiology and is concerned with the study and ...
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Electrical conduction system of the heart
The cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through ...
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Supraventricular tachycardia
References
{{Circulatory system pathology
Cardiac arrhythmia