A report on Atrioventricular node and Electrical conduction system of the heart

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

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

Isolated heart conduction system showing atrioventricular node

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 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.

- Atrioventricular node

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.

- Electrical conduction system of the heart

3 related topics with Alpha

Heart

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Muscular organ in most animals.

Computer-generated animation of a beating human heart

The human heart is in the middle of the thorax, with its apex pointing to the left.

Heart being dissected showing right and left ventricles, from above

Frontal section showing papillary muscles attached to the tricuspid valve on the right and to the mitral valve on the left via chordae tendineae.

Layers of the heart wall, including visceral and parietal pericardium

The swirling pattern of myocardium helps the heart pump effectively

Arterial supply to the heart (red), with other areas labelled (blue).

Development of the human heart during the first eight weeks (top) and the formation of the heart chambers (bottom). In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a very different pattern from that of an adult.

The cardiac cycle as correlated to the ECG

The x-axis reflects time with a recording of the heart sounds. The y-axis represents pressure.

Transmission of a cardiac action potential through the heart's conduction system

The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarization and repolarization. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarization and contraction of the cell; there is no resting potential.

3D echocardiogram showing the mitral valve (right), tricuspid and mitral valves (top left) and aortic valve (top right).
The closure of the heart valves causes the heart sounds.

Heart and its blood vessels, by Leonardo da Vinci, 15th century

Elize Ryd making a heart sign at a concert in 2018

The tube-like heart (green) of the mosquito Anopheles gambiae extends horizontally across the body, interlinked with the diamond-shaped wing muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei.

Basic arthropod body structure – heart shown in red

The human heart viewed from the front and from behind

Heart illustration with circulatory system

Animated Heart 3d Model Rendered in Computer

These generate a current that causes the heart to contract, traveling through the atrioventricular node and along the conduction system of the heart.

Sinoatrial node

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Group of cells known as pacemaker cells, located in the wall of the right atrium of the heart.

Figure 2: Low magnification stained image of the SA node (center-right on image) and its surrounding tissue. The SA node surrounds the sinoatrial nodal artery, seen as the open lumen. Cardiac muscle cells of the right atrium can be seen to the left of the node, and fat tissue to the right.

Figure 3: Sinoatrial node action potential waveform, outlining major ion currents involved (downward deflection indicates ions moving into the cell, upwards deflection indicates ions flowing out of the cell).

Schematic representation of the atrioventricular bundle

These cells can produce an electrical impulse (action potential) that travels through the electrical conduction system of the heart, causing it to contract.

Other cells within the heart (including the Purkinje fibers and atrioventricular node) can also initiate action potentials; however, they do so at a slower rate and therefore, if the SA node is functioning properly, its action potentials usually override those that would be produced by other tissues.

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

Arrhythmia

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Too fast or too slow.

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

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.

Arrhythmias are due to problems with the electrical conduction system of the heart.

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).