How to read the ECG? How can I decode an electrocardiogram myself? What the ECG shows

Electrocardiograph (ECG) - a device that allows you to assess cardiac activity, as well as to diagnose the condition of this organ. During the examination, the doctor receives the data in the form of a curve. How to read the ECG curve? What kind of teeth are there? What changes are visible on the ECG? Why do doctors need this method of diagnosis? What does the ECG show? This is far from all the questions that interest people who are faced with electrocardiography. . First you need to find out how the heart is arranged .

The heart of a man consists of two atria and two ventricles. The left side of the heart is more developed than the right side, since it puts a heavy load on it. It is this ventricle that most often suffers. Despite the difference in size, both sides of the heart should work stably, cohesively.

Learning to read an electrocardiogram yourself

How to read the ECG correctly? This is not so difficult as it might seem at first glance. First you should look at the cardiogram. It is printed on special paper with cells, and two types of cells are clearly visible: large and small.

Conclusion ECG is read by these cells. What do ECG- teeth show , cells? These are the main parameters of the cardiogram. Let's try to learn how to read the ECG from scratch.

The value of cells (cells)

On paper for printing the result of the survey there are two types of cells: large and small. They all consist of vertical and horizontal guides. Vertical is the voltage, and horizontal is the time.

Large squares consist of 25 small cells. Each small cell is 1 mm and corresponds to 0.04 seconds in the horizontal direction. The large squares are 5 mm and 0.2 seconds. In the vertical direction, the centimeter of the strip is equal to 1 mV of voltage.

Zubtsy

To read the ECG conclusion, you need to know which teeth are there and what they mean.

A total of five teeth are identified. Each of them on the graph displays the work of the heart.

1. P - ideally this tooth should be positive within the range of 0.12 to 2 seconds.
2. Q - a negative tooth, shows the condition of the interventricular septum.
3. R - displays the state of the myocardium of the ventricles.
4. S - negative tooth, shows the completion of processes in the ventricles.
5. T - a positive prong, shows the restoration of the potential in the heart.

All ECG teeth have their own reading characteristics.

Zubets R

All the electrocardiogram teeth have a definite value for the diagnosis.

The very first tooth of the graph is called P. It denotes the time between the palpitations. To measure it, it is best to select the beginning and end of the tooth with vertical lines, and then count the number of small cells. Normally the tooth P should be between 0.12 and 2 seconds.

However, measuring this indicator only on one site will not give exact results. To make sure that the heartbeat is smooth, it is necessary to determine the interval of the P wave at all sites of the electrocardiogram.

Prong R

Knowing how to read an electrocardiogram in an easy way, you can understand if there are pathologies of the heart. The next important tooth of the graph is R. It's easy to find it - it's the highest peak on the chart. This will be a positive prong. Its highest part is marked on the cardiogram R, and its lower parts Q and S.

The QRS complex is called ventricular, or sinus. In a healthy person, the sinus rhythm on the ECG is narrow, high. The figure clearly shows the teeth of ECG R, they are the highest:

Between these peaks, the number of large squares indicates the heart rate (heart rate). This indicator is calculated by the following formula:

300 / number of large squares = heart rate.

For example, between the peaks are four full squares, then the calculation will look like this:

300/4 = 75 beats per minute.

Sometimes on the cardiogram, the QRS complex is extended more than 0.12 s, which indicates the blockade of the bundle of His.

Interval between teeth PQ

PQ is the interval from the P wave to Q. It corresponds to the time of excitation of the atria to the ventricular myocardium. The norm of the PQ interval at different ages is different. Usually it is 0.12-0.2 seconds.

With age, the interval increases. Thus, in children under 15 years of age, PQ can reach 0.16 s. At the age of 15 to 18 years, PQ increases to 0.18 s. In adults, this figure is equal to a fifth of a second (0.2).

When the interval is extended to 0.22 s, they speak of a bradycardia.

Interval between QT teeth

To know how to read the ECG correctly, you need to understand the intervals. After the determination of the teeth, the calculation of the QT interval begins. Normally, it is 400-450 ms.

If this complex is longer, then we can assume IHD, myocarditis or rheumatism. With a shortened type, hypercalcemia can be noted.

Interval ST

Normally, this indicator is located at the midline level, but it can be higher than it by two cells. This segment shows the process of restoring the depolarization of the heart muscle.

In rare cases, the indicator may rise three cells above the midline.

Norm

Decoding of the cardiogram in the norm should look like this:

• Segments Q and S should always be below the midline, that is, negative.
• R и T в норме должны располагаться выше средней линии, т. е. будут положительными. The teeth R and T should normally be located above the midline, that is, they will be positive.
• QRS-complex should not be wider than 0.12 s.
• The heart rate should be between 60 and 85 beats per minute.
• There must be a sinus rhythm on the ECG.
• R should be higher than the tooth of S.

ECG in pathologies: sinus arrhythmia

And how to read the ECG for various pathologies? One of the most frequent heart diseases is a sinus rhythm disturbance . It can be pathological and physiological. The latter type is usually diagnosed in people involved in sports, with neuroses.

With sinus arrhythmia, the cardiogram has the following form: sinus rhythms are preserved, fluctuations of the RR intervals are observed, but during the delay of breathing the graph is flat.

With pathologic arrhythmia, the preservation of the sinus pulse is observed continuously, regardless of the delay in breathing, while wave-like changes are observed at all RR intervals.

Manifestation of an infarction on the ECG

When there is a myocardial infarction, changes on the ECG are clearly pronounced. The signs of pathology are:

• Increased heart rate;
• The ST segment is upgraded;
• In the ST leads there is a fairly persistent depression;
• The QRS complex increases.

In case of a heart attack, the cardiogram is the main means of recognizing the necrosis zones of the heart muscle. With its help you can determine the depth of the organ damage.

With an infarction on the chart, an increase in the ST segment is observed, and the R wave is lowered down, giving the ST a shape reminiscent of the cat's back. Sometimes, in pathology, there may be changes in the Q wave.

Ischemia

If there is an ischemia on the ECG, you can see in which part it is located.

• Location of ischemia at the anterior wall of the left ventricle. Diagnosed with symmetrical pointed T-teeth.
• Location of the left ventricle epicardium. T-tooth pointed, symmetrical, directed downward.
• Transmural type of ischemia of the left ventricle. T is pointed, negative, symmetrical.
• Ischemia in the myocardium of the left ventricle. T is smoothed, slightly raised.
• The defeat of the heart by ischemic disease is indicated by the condition of the T wave.

Changes in the ventricles

ECG shows changes in the ventricles. Most often they appear in the left ventricle. This kind of cardiogram occurs in people with prolonged additional workload, for example, with obesity. With this pathology, the electric axis deviates to the left, against which the tooth S becomes higher than R.

The Holter method

And how to learn to read the ECG, if it is not always clear what teeth and how are located? In such cases, a continuous recording of the cardiogram using a mobile device is prescribed. . He constantly writes ECG data to a special tape .

This method of examination is necessary in those cases, if the classical ECG can not detect pathologies. During the diagnosis of Holter, a detailed diary is always kept, where the patient records all his actions: sleep, walks, sensations during activity, all activity, rest, symptoms of illness.

Usually, data are recorded within 24 hours. However, there are times when it is necessary to take readings for up to three days.

Schemes of ECG decoding

When decoding the cardiogram, it is recommended to follow a certain sequence.

1. Conductivity and heart rhythm are analyzed. To do this, the heart rate is assessed regularly, the number of heart rate is calculated, and the conducting system is determined.
2. Axial rotations are detected: the position of the electric axle in the frontal plane is determined; Around the transverse, longitudinal axis.
3. The tooth R.
4. The QRS-T is analyzed. The state of the QRS complex, RS-T, T wave, and the QT interval are evaluated.
5. A conclusion is drawn.

According to the duration of the RR-cycle, there is talk about the regularity and rate of heart rhythm. When evaluating the heart, not one RR gap is assessed, but all. Normally, deviations are allowed within 10% of the norm. In other cases, the abnormal (pathological) rhythm is determined.

To establish the pathology, the QRS complex and a certain time section are taken. It calculates how many times the segment is repeated. Then the same time interval is taken, but further on the cardiogram, again counted. If in equal parts of time the amount of QRS is the same, then this is the norm. At different amounts - the pathology is assumed, while they are oriented to the teeth of P. They should be positive and stand in front of the QRS complex. Throughout the chart, the form P should be the same. This option speaks about the sinus rhythm of the heart.

At the atrial rhythms, the tooth P is negative. It is followed by the QRS segment. In some people, the P tooth on the ECG may be absent, completely merging with QRS, which indicates the pathology of the atria and ventricles, which the impulse achieves simultaneously.

The ventricular rhythm is shown on the electrocardiogram by deformed and expanded QRS. In this connection, the relationship between P and QRS is not visible. Between the teeth R is large distances.

Cardiac conduction

The cardiac conductance is determined from the ECG. At the tooth P, the atrial pulse is determined, normally this should be 0.1 s. The P-QRS interval displays the overall rate of conduction in the atria. The rate of this indicator should be in the range of 0.12 to 0.2 s.

The segment QRS shows conduction through the ventricles, the norm is the limit from 0.08 to 0.09 s. When the intervals increase, the cardiac conduction slows down.

What the ECG shows, patients do not need to know. This must be understood by a specialist. Only a doctor can correctly decipher a cardiogram and put the correct diagnosis, given the degree of deformation of each individual tooth, segment.

It is not always possible to read the result of an electrocardiogram independently due to a lack of experience and fuzzy teeth, segments, intervals, and also paper features.