Accelerated idioventricular rhythm
Encyclopedia
In accelerated idioventricular rhythm, the rate of cardiac contraction is determined by the intrinsic rate of depolarisation of the cardiac cells.
It can be present at birth.
in the atria depolarises at a rate of 70 beats per minute as an effect of the parasympathetic autonomic nervous system (otherwise the SA node would depolarise at a rate of 120 beats per minute). This suppresses the intrinsic depolarisation of the other parts of the heart.
The accelerated idioventricular rhythm occurs when depolarization rate of a normally suppressed focus increases to above that of the "higher order" focuses (the sinoatrial node and the atrioventricular node
). This most commonly occurs in the setting of a sinus bradycardia
.
Accelerated idioventricular rhythm is also the most common reperfusion arrhythmia in humans. However, ventricular tachycardia and ventricular fibrillation remain the most important causes of sudden death following spontaneous restoration of antegrade flow.
but is benign and doesn't need any treatment. It can most easily be distinguished from VT in that the rate is less than 120 and usually less than 100 bpm.
It can be present at birth.
Pathophysiology
In normal hearts the sinoatrial nodeSinoatrial node
The sinoatrial node is the impulse-generating tissue located in the right atrium of the heart, and thus the generator of normal sinus rhythm. It is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava...
in the atria depolarises at a rate of 70 beats per minute as an effect of the parasympathetic autonomic nervous system (otherwise the SA node would depolarise at a rate of 120 beats per minute). This suppresses the intrinsic depolarisation of the other parts of the heart.
The accelerated idioventricular rhythm occurs when depolarization rate of a normally suppressed focus increases to above that of the "higher order" focuses (the sinoatrial node and the atrioventricular node
Atrioventricular node
The atrioventricular node is a part of the electrical control system of the heart that coordinates heart rate. It electrically connects atrial and ventricular chambers...
). This most commonly occurs in the setting of a sinus bradycardia
Sinus bradycardia
Sinus bradycardia is a heart rhythm that originates from the sinus node and has a rate of under 60 beats per minute.-Signs and symptoms:The decreased heart rate can cause a decreased cardiac output resulting in symptoms such as lightheadedness, dizziness, hypotension, vertigo, and syncope...
.
Accelerated idioventricular rhythm is also the most common reperfusion arrhythmia in humans. However, ventricular tachycardia and ventricular fibrillation remain the most important causes of sudden death following spontaneous restoration of antegrade flow.
Appearance
AIVR appears similar to ventricular tachycardiaVentricular tachycardia
Ventricular tachycardia is a tachycardia, or fast heart rhythm, that originates in one of the ventricles of the heart...
but is benign and doesn't need any treatment. It can most easily be distinguished from VT in that the rate is less than 120 and usually less than 100 bpm.