Electrocardiogram

  First, ECG or electrocardiogram means an electrocardiogram or electrocardiograph, and in some countries such as Germany it is called EKG, i.e. (Electrocardiogram).

Diagnosing diseases depends mainly on first taking the patient's history well, along with performing some tests, and the ECG machine confirms the diagnosis of many medical conditions, and in some cases it is very important for treatment.

The ECG is very important in diagnosing many conditions, including:

1.    Changes in regular rhythmic heartbeats.

2.    It helps diagnose the cause of chest pain.

3.    The use of clot-dissolving drugs in cases of myocardial infarction depends on the ECG.

4.    It also helps diagnose the cause of breathlessness.

Always remember that by the end of this article, you will say how easy it is to read an ECG!!

I want you to follow the topic with the images provided, because they will make things easier for you.

And so that you do not get lost in the topic, we will talk about the subject of ECG in the following order:

First: We will talk about the electrical activity of the heart and how the heart beats.

Second: We will talk about the ECG machine, how an ECG is performed, and its images.

     Third: We will cover the topic of what we will read on the ECG paper.

First: Heart electricity

:  ( Heart electricity)

  The contraction of any muscle is accompanied by electrical currents called (depolarization), and these currents can be recorded by electrodes, and these electrodes are connected to the body surface. Therefore, we can record the contraction of all the body's muscles, and thus if we want to record the contraction of only the heart muscles clearly, the person must be resting and all other muscles of his body relaxed.

 Although the heart contains 4 chambers, we will see only two chambers in the electrical imaging because the atria contract together and the ventricles also.

Normal heartbeat:

The regular rhythmic heartbeats originate from within the heart muscle tissue itself, as it is self-moving, where the normal heartbeat begins with an electrical signal emitted from a specialized small-sized neuro-muscular electrical generator and regulator located in the wall of the right atrium called the (sinoatrial node), at a rate of 60-100 beats/electrical signals per minute. This electrical signal spreads very quickly to the atria, causing them to contract to push blood from the atria to the ventricles. Then this electrical signal travels to a receiver, which in the same case is considered a small-sized backup generator located between the ventricles and atria, called the (atrioventricular node), which allows the electrical signal to pass through electrical connections branching from the atrioventricular node to the ventricles in a fraction of a second, causing them to contract to push blood from the ventricles out of the heart. The right ventricle pushes deoxygenated blood to the lungs to be oxygenated, and the left ventricle pushes oxygenated blood to all parts of the body to benefit from the oxygenated blood that returns after oxygen is extracted from it to the right side of the heart, and thus one complete blood circulation is completed.

Thus, in a normal person, the electrical signals originate from the (sinoatrial node), and in this case the system is called (sinus rhythm). However, in some pathological cases, the currents can originate from another source such as the (atrioventricular node), and the system in this case is called (nodal rhythm), or it may originate from any other source such as the ventricular muscle itself, and this may be due to the failure of the sinoatrial node to emit impulses or the presence of an external source - anywhere else in the heart - beating at a higher rate than the primary pacemaker, so it takes its place.

Second: How an ECG is performed:

The wires pass from the ECG machine to electrodes, which are electrically conductive metal strips. The electrodes are placed on each arm and leg and at six points on the chest, above the heart area.

The electrodes capture the currents produced by the heart with each of its beats and transmit them to an amplifier inside the electrocardiograph. The amplified currents then flow through a very thin wire coil suspended within a magnetic field, and the wire moves due to the interaction of these currents with the magnetic field. A sensitive lever records the movement of the wire on moving graph paper, resulting in an ECG in the form of images called leads.

Each heartbeat produces a series of wave lines. The normal heartbeat of the heart gives a specific wave pattern. Certain types of heart disease change this known pattern in a recognizable way.

ECG images (leads):

Each electrode connected to the body is considered a camera, and we place 10 electrodes on the human body, one on each arm and each leg and at six points on the chest, and thus we get 10 electrodes (cameras) from different directions. Each camera produces a different image from the other camera because each one captures the heart's view from a different angle, but it is the same view, like a football match, where we find that there is more than one camera in the stadium and each one captures a certain view from a certain angle, but it is the same match...

The ECG machine produces 12 images (leads) and t