A report on Arrhythmia, Atrial fibrillation and Atrioventricular node

Ventricular fibrillation (VF) showing disorganized electrical activity producing a spiked tracing on an electrocardiogram (ECG)

Leads aVL and aVF of an electrocardiogram showing atrial fibrillation. There are irregular intervals between heart beats. No P waves are seen and there is an erratic baseline between QRS complexes. The heart rate is about 125 beats per minute.

Image showing the conduction system of the heart. The AV node is labelled 2.

Broad classification of arrhythmias according to region of heart required to sustain the rhythm

Normal rhythm tracing (top) Atrial fibrillation (bottom)

Isolated heart conduction system showing atrioventricular node

Normal sinus rhythm, with solid black arrows pointing to normal P waves representative of normal sinus node function, followed by a pause in sinus node activity (resulting in a transient loss of heartbeats). Note that the P wave that disrupts the pause (indicated by the dashed arrow) does not look like the previous (normal) P waves – this last P wave is arising from a different part of the atrium, representing an escape rhythm.

How a stroke can occur during atrial fibrillation

Non-modifiable risk factors (top left box) and modifiable risk factors (bottom left box) for atrial fibrillation. The main outcomes of atrial fibrillation are in the right box. BMI=Body Mass Index.

A 12-lead ECG showing atrial fibrillation at approximately 132 beats per minute

Diagram of normal sinus rhythm as seen on ECG. In atrial fibrillation the P waves, which represent depolarization of the top of the heart, are absent.

ECG of atrial fibrillation (top) and normal sinus rhythm (bottom). The purple arrow indicates a P wave, which is lost in atrial fibrillation.

3D Medical Animation still shot of Left Atrial Appendage Occlusion

Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm (arrhythmia) characterized by rapid and irregular beating of the atrial chambers of the heart.

- Atrial fibrillation

Supraventricular tachycardias include atrial fibrillation, atrial flutter and paroxysmal supraventricular tachycardia.

- Arrhythmia

This also protects the ventricles from excessively fast rate response to atrial arrhythmias (see below).

- Atrioventricular node

This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter.

- Atrioventricular node

The impulse initially causes both atria to contract, then activates the atrioventricular node (AV node), which is normally the only electrical connection between the atria and the ventricles (main pumping chambers).

- Arrhythmia

These disorganized waves conduct intermittently through the atrioventricular node, leading to irregular activation of the ventricles that generate the heartbeat.

- Atrial fibrillation

2 related topics with Alpha

Atrial flutter

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Type I atrial flutter, counterclockwise rotation with 3:1 and 4:1 AV nodal block.

Atrial flutter with a two to one block. Note the P waves hiding in the T waves in leads V1 and V2

Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart.

It is typically not a stable rhythm, and often degenerates into atrial fibrillation (AF).

Impulses from the atria are conducted to the ventricles through the atrio-ventricular node (AV node).

AV nodal reentrant tachycardia

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Type of abnormal fast heart rhythm.

During typical AVNRT, electrical impulses travel down the slow pathway of the AV node and back up the fast pathway.

AVNRT termination following administration of adenosine

AVNRT occurs when a reentrant circuit forms within or just next to the atrioventricular node.

All these ECG-based technologies also enable the distinction between AVNRT and other abnormal fast heart rhythms such as atrial fibrillation, atrial flutter, sinus tachycardia, ventricular tachycardia and tachyarrhythmias related to Wolff-Parkinson-White syndrome, all of which may have symptoms that are similar to AVNRT.