A report on Arrhythmia and Atrioventricular node

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

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

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

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Overall
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.

Atrial fibrillation

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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.
Normal rhythm tracing (top) Atrial fibrillation (bottom)
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.

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

An example of an ECG tracing typical of uncommon AV nodal reentrant tachycardia. Highlighted in yellow is the P wave that falls after the QRS complex.

AV nodal reentrant tachycardia

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Type of abnormal fast heart rhythm.

Type of abnormal fast heart rhythm.

An example of an ECG tracing typical of uncommon AV nodal reentrant tachycardia. Highlighted in yellow is the P wave that falls after the QRS complex.
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.

Atrial flutter with varying A-V conduction (5:1 and 4:1)

Atrial flutter

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Atrial flutter with varying A-V conduction (5:1 and 4:1)
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.

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

Heart; conduction system. 1. SA node. 2. AV node. 3. Bundle of His. 8. Septum

Electrical conduction system of the heart

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The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node in the heart to cause contraction of the heart muscle.

The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node in the heart to cause contraction of the heart muscle.

Heart; conduction system. 1. SA node. 2. AV node. 3. Bundle of His. 8. Septum
Overview of the system of electrical conduction which maintains the rhythmical contraction of the heart
Principle of ECG formation. Note that the red lines represent the depolarization wave, not bloodflow.
Different wave shapes generated by different parts of the heart's action potential

The pacemaking signal generated in the sinoatrial node travels through the right atrium to the atrioventricular node, along the Bundle of His and through bundle branches to cause contraction of the heart muscle.

Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow.