Electrical conduction system of the heart: what is it and how does it work?

This set of body parts allows the circulatory system to function well.

Have you ever wondered how the heart beats? In order for the heart to beat and pump Blood to the different parts of our organism, it operates through the so-called electrical conduction system of the heart.

In this article we will briefly explain what the human heart looks like and how it works, what the electrical conduction system of the heart consists of and how it operates.. Finally, we will talk about arrhythmias, a disturbance that occurs when this system fails.

The heart

Before talking about the electrical conduction system of the heart, and how it works, we will briefly explain what the heart is and what are its functions.

The word heart comes from the Latin word cor, and it is the main organ of the circulatory system. The circulatory system is used to transport internally the different substances that living beings need to live: hormones, nutrients, oxygen, carbon dioxide...

In terms of its characteristics, the heart is a hollow muscular organ. It works like a pump, propelling blood through the arteries, in order to distribute it throughout the body.It works like a pump, propelling blood through the arteries in order to distribute it throughout our body. Its size is that of a fist, and its weight is between 250 and 300 grams (in women) and 300 and 350 grams (in men). This is approximately 0.4% of our body weight. Anatomically, the heart is located in the center of the thoracic cavity, between the lungs.

Thus, the heart is the pump of the muscular tissue, which pumps blood through the organism. On the other hand, the electrical conduction system of the heart coordinates the contraction of the different chambers of the heart. of the heart.

Structures of the heart

What structures are part of the heart, and thus of the heart's electrical conduction system? There are 4 of them:

• Right atrium (RA)
• Right ventricle (RV)
• Left atrium (LA)
• Left Ventricle (LV)

Now let's take a look at how the electrical conduction system of the heart works.

Electrical conduction system of the heart

The heart's electrical conduction system has the primary function of allowing the blood that is pumped by the heart to be distributed throughout the body (i.e., pumped throughout the body). It coordinates the contractions of the heart chambers so that the heart beats correctly.

More specifically, it is a system that allows the impulse generated by a node of the heart, the sinus node, to propagate and stimulate an important cardiac muscle, the myocardium. In this way, the myocardium contracts.

Thus, this system involves a series of myocardial coordinations, which cause the heart to the heart to contract efficiently, and, as we said, this is how the heart contracts.and, as we said, the blood is pumped throughout the body.

Components, location and function.

The main components of the electrical conduction system of the heart are two, the sinoatrial (SA) or sinus node and the atrioventricular node. We will explain what each of them consists of, and how the electrical conduction system of the heart operates through these nodes (i.e. how the heart beats):

1. sinoatrial (SA) node.

It could be said that the sinoatrial node is the natural pacemaker of the heart. This module also goes by other names, such as sinus node, Keith and Flack node or heart pacemaker.. Anatomically, the SA is located in the posterior superior part of the right atrium of the heart, just at the entrance of the superior vena cava.

In terms of its characteristics, it is the largest cardiac pacemaker, and its shape is oval. It is in this node where the electrical impulse is born, which travels and spreads throughout the atria.. It does so through pathways called internodal pathways, causing the atria to contract.

In healthy adults, the sinus node discharges at a rate of 60 impulses per minute (60 contractions per minute), i.e. the electrical stimulus is generated regularly between 60 and 100 times per minute.

2. Atrioventricular (AV) node

It is then that the electrical impulse reaches the next node, the atrioventricular node (also called the Aschoff-Tawara node). Its size is 40% of the size of the previous node, the sinus node. It is oval in shape, and is located on the left side of the right atrium, specifically in a structure called the septum.It is oval in shape, and is located in the left side of the right atrium, specifically in a structure called the interatrial septum.

Almost always (in 90% of cases), the atrioventricular node is supplied by a branch located in the right coronary artery. This node has two types of innervation: sympathetic and parasympathetic..

It is in the atrioventricular node where the electrical impulse (or electrical wave) stops for less than 1 second (specifically, for 0.13 seconds).

And then what...?

After this pause of the electrical impulse in the atrioventricular node, this impulse The His bundle, a bundle of fibers that acts as a bridge between the nodal which acts as a bridge between the node and the branches of the ventricles.

This bundle divides into two more branches: the right and the left. Another division appears on the left: the anterior left bundle, the posterior left bundle and the middle or septal bundle. From From this last fascicle the electrical impulse is distributed to the ventricles, through the Purkinje fibers, fibers that allow the contraction of the ventricles.The Purkinje fibers, fibers that allow ventricular contraction.

Abnormal functioning of the electrical conduction system of the heart

We have talked about how the electrical conduction system of the heart works in normal or healthy conditions, that is, when our heart beats normally and the different parts of the body receive blood pumping normally.

But... what happens when there is a malfunction? Then situations or phenomena such as arrhythmias occur.

Arrhythmias

An arrhythmia is a disorder of the heart rate or heart rhythm.In these cases, the heart may beat faster than usual (tachycardia), it may beat too slowly (bradycardia) or it may beat irregularly.

In other words, arrhythmias involve abnormal heartbeats. The arrhythmias themselves may not be harmful, although they are sometimes a sign of underlying problems, or of imminent danger.or of an imminent danger to our health.

When and why do arrhythmias occur? They can occur in different cases and situations. The three most frequent are the following:

• When another part of the heart acts as a pacemaker (i.e. takes over this role).
• When the natural pacemaker of our heart (i.e. the sinus node) produces an abnormal rhythm (rate).
• When the normal conduction pathway is interrupted for some reason.

Symptoms

As we can see, when the heart's electrical conduction system fails, arrhythmias may appear. But, what symptoms does this disorder or alteration of the heart rhythm produce? Mainly arrhythmias produce 4 symptoms: shortness of breath, dizziness, fainting and palpitations.

To evaluate this problem, an electrocardiogram (ECG) is used to evaluate this problem.which makes it possible to determine and analyze the rhythm of our heart. An ECG is a painless test that records the cardiac electrical activity through different electrodes placed on the chest.

Sometimes, when the electrical rhythm is not normal, medication or surgery may be necessary. A specialist physician should always be consulted to evaluate and treat our case.