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An idioventricular rhythm is a cardiac rhythm characterized by a rate of <50 beats per minute (bpm), absence of conducted P waves and widening of the QRS complex. In cases where the heart rate is between 50 and 110 bpm, it is known as accelerated idioventricular rhythm and ventricular tachycardia if the rate exceeds 120 bpm. Causes of idioventricular rhythms are varied and can include drugs or a heart defect at birth. It is typically benign and not life-threatening.


Etiology

Various etiologies may contribute to the formation of an idioventricular rhythm, and include: * Heart block * Reperfusion after
myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
* Electrolyte abnormalities * Heart diseases present at birth * Certain drugs (eg.
digoxin Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...
, β-agonists, anaesthetics)


Pathophysiology

The physiological pacemaker of the heart is the
sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node, sinus node or Keith–Flack node) is an ellipse, oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of Cell (biology), cells known as pa ...
. If the sinoatrial node is rendered dysfunctional, the AV node may act as the pacemaker.{{cite book , last1=Guyton , first1=Arthur C. , last2=Hall , first2=John E. , title=Textbook of Medical Physiology , pages=120–121 , edition=11 If both of these fail, the ventricles begin to act as the dominant pacemaker in the heart. The ventricles acting as their own pacemaker gives rise to an idioventricular rhythm.


Diagnosis

An ECG trace is required for diagnosis.


Treatment

As this rhythm is not life-threatening, treatment has limited value for the patient. If underlying pathologies are identified, they should be treated appropriately. In the absence of other life-threatening arrhythmias, antiarrhythmics should be avoided as they can blunt the ventricular rate leading to hemodynamic collapse.


References

Cardiac arrhythmia