Probably every adult at least once in his life has come across such a method of examination as an ECG. Many people know that this abbreviation stands for “electrocardiogram” and with its help the heart rhythm is recorded. On this, perhaps, for most patients, all knowledge ends and on the resulting tape they see nothing but a broken line.
For especially curious people who want to find out about their state of health even before visiting a specialist, let's try to figure out how the ECG is decoded and what can be learned from it.
Moreover, on our website you can always get advice from a qualified cardiologist who can interpret the data on the cardiogram tape in detail and accurately.
ECG is not only a modern, but also the most accessible method for determining the characteristics of heart activity. Thanks to portable devices, the procedure can be carried out and read in almost extreme conditions: on the street, at home, in an ambulance or in other transport, and it takes only 5-7 minutes.
Indications for this procedure can be any unpleasant sensations that appear in the chest, with “echoes” of pain in the back, left arm, and abdominal cavity. In addition, a doctor of any specialization can refer a patient to an ECG as part of a routine examination or if he has:
- severe shortness of breath;
- hypertension;
- interruptions in the rhythm of the heart or noise in it;
- frequent fainting (or after a single case);
- causeless weakness;
- swelling of the extremities, etc.
Patients who have had a heart attack or stroke should be examined according to the prescription of the attending physician. In some cases, it is necessary to record the indicators of the daily work of the heart or with loads. And in order to prevent malfunctions in the work of the organ, even a healthy person should undergo an electrocardiography procedure at least 1 time in 1-2 years.
Can the heart be recorded?
To understand how to decipher a cardiogram, you should learn a little about the principle of the human heart and the method of taking an ECG.
On the wall of the right atrium there is a sinus node, from which the propagation of impulses normally begins. Passing through the muscles of the atrium, the excitation reaches the antroventricular node, then into the bundle of His and along its legs, the impulse propagates through the tissues of the ventricles. All this causes 4 sections of the heart to contract. It is this pattern of excitations that is normal and gives rise to sinus rhythm.
As you know, the human body has electrical conductivity, so the biocurrents of the heart can be projected onto its surface and recorded using ECG devices.
From the point of view of physics, an electrocardiogram is nothing more than a registration of electrical signals, which is carried out from several sections of the heart muscle. To do this, plates are attached to certain points of the body that transmit signals to the ECG apparatus.
In practice, 3 standard bipolar leads (I, II, III), 3 reinforced unipolar leads (aVR, aVL, aVF), which are attached to the limbs, and 6 reinforced unipolar chest leads (V 1 -V 6) are used. But, despite the simplicity of their layout, only a trained physician can correctly fix the electrodes, otherwise the ECG results will be incorrect. Three more leads (V 7 -V 9) are less commonly used, which provide more accurate information about abnormalities in the myocardium of the posterior wall of the left ventricle.
From the video below, you can learn more about the propagation of impulses in the heart and the correct application of electrodes during an ECG.
Prongs and intervals
All received electrical signals are converted into graphic information and applied to a special tape, which is divided into squares of 1 mm 2 . Thus, we see the whole process of the work of our heart as a curve with pronounced teeth, for convenience they have their own “names”: P, Q, R, S, T.
Each tooth reflects certain actions of the heart muscle and their duration:
- P - excitation of the right and then the left atrium, united by one tooth (at least 0.12 s.);
- Q - excitation of the interventricular septum (0.03 s);
- R - excitation of the apex of the heart with the adjacent area (0.05 s.);
- S - excitation of the base of the organ (0.02 s.);
The Q, R, S waves are considered as a single ventricular complex (0.10 s).
- T - this wave displays repolarization, that is, the restoration of the initial state of all parts of the heart.
The teeth form corresponding segments and intervals between themselves.
When deciphering a cardiogram, specialists usually adhere to a certain sequence.
Heart rate and frequency
Normally, the rhythm should be sinus, that is, the impulse "originates" in the sinus node. This will be indicated by the P wave, which should precede the QRS complex and be positive in all leads except aVR. If this is not the case, then we can talk about the pathology of the heart. In case of weakness of the sinus node, the atrioventricular node, bundles of His, or Purkinje fibers can become the pacemaker. This information can be indicated by the functional diagnostician on the ECG tape. In addition, it indicates the heart rate (HR), which, however, can be calculated independently. To do this, it is enough to find out at what speed the ECG was recorded and find out the distance R-R (count the number of small squares between them).
If the writing speed is 25 mm / s, then it should be calculated according to the following formula:
HR= 60/R-R*0.04;
If - 50 mm / s, then heart rate \u003d 60 / R-R * 0.02;
For an adult, the normal heart rate is 60-90 beats per minute. For children, all indicators of the cardiogram change and "grow" with them. For example, the frequency varies from 110 in the first months of life to 90 strokes in adolescence.
If the rhythm is accelerated, then this indicates tachycardia, if slowed down, then bradycardia, and if the R-R distance is not the same, then this condition is called arrhythmia.
The figure shows examples of normal heart rhythm (a), tachycardia (b), bradycardia (c) and irregular rhythm (arrhythmia) of an adult (d).
Electrical axis of the heart
Next, the specialist draws attention to the location of the EOS. It can be not only normal, but also have a vertical, horizontal orientation, or be deviated to one of the sides. This indicator may depend on several factors at once - high growth, overweight, age, pregnancy, etc., therefore, it is not worth immediately and unequivocally making conclusions about deviations in the work of an adult organ. However, as well as ignore the changes, especially if the axis shift happened quite abruptly. This may indicate problems with the respiratory system, the development of heart disease, changes in the myocardium, atherosclerosis, etc. In this case, an additional examination of the patient will be scheduled.
When reading an ECG to determine the EOS, the following algorithm is used.
Wave and spacing analysis
ECG analysis is not complete without monitoring the waves and intervals. It all starts with the P wave, which, as mentioned above, should be sinus. If it has an increased amplitude or duration in the second lead, then this may indicate hypertrophy of the right or left atrium, respectively. Further, by evaluating the PQ interval, it is possible to identify the blockade of the antroventricular node, which is characterized by an increased duration of the PQ interval or its complete absence.
A separate point in the analysis of the ECG is the reading of the QRS complex. Normally, its duration is 60-100 ms. Its elongation is evidence of a conduction disturbance in the legs of the His bundle. Below are examples of areas of the ECG, where the blockade of the right and left legs is clearly visible.
Moreover, a Q wave deeper than 1/3 of the R wave may indicate myocardial infarction.
The QT interval displays the duration of ventricular contraction and is 390-450 ms. Its lengthening indicates the development of coronary heart disease, and its shortening indicates hypercalcemia. The ST segment normally should not rise above the isoline by more than 1 mm and decrease by more than 0.5 mm. Violation of the first condition indicates an acute infarction or pericarditis, and the second - about ischemia.
The video shows the sequence and more detailed decoding of all the teeth of the ECG intervals:
But no matter how detailed such information is presented, it should be understood that only a specialist can correctly interpret the cardiogram.
The ruler is an indispensable assistant
Sometimes it happens that a person's life depends on precious minutes, during which the doctor must understand what is the reason for the deterioration of the patient's condition and take appropriate measures. Ambulance paramedics sometimes have to make a diagnosis right at the patient's home, relying only on electrocardiography indicators. It goes without saying that the analysis in such a situation must be carried out extremely quickly and at the same time correctly. For such emergencies and to help medical students, a ruler was developed for interpreting the obtained ECG.
With its help, you can quickly read the ECG: determine the heart rate, measure and compare intervals with the norm, their duration, and also determine the EOS. Such an invention as a ruler can also become useful when trying to decipher the ECG on your own.
Other ways to look into the "motor" of the human body
In addition to the electrocardiogram, modern medicine has methods for examining the heart, such as echocardiography and the method of daily heart rate monitoring.
Holter method
This method allows you to obtain continuous data on the work of the heart for 24 hours (and sometimes even up to 7 days). Daily monitoring allows you to identify pathologies that are determined in special conditions. To do this, 2 or 3 electrodes (rarely more) are attached to the patient's body, a registrar is worn on the belt or over the shoulder on the belt, which keeps a continuous record. At the same time, the subject leads a normal life, with the usual physical activity, recording the time and circumstances in which unpleasant sensations appeared.
Recorders are divided into those that record on magnetic media and those that have digital memory. The analysis of the accumulated information is carried out on a computer with the software installed for this, but it is not complete without adjusting the results by a specialist. The conclusion on daily monitoring of the work of the heart contains the same mandatory items as in a conventional ECG. Only information about well-being is added, according to the diary, prescribed loads and related changes.
Echocardiogram
Like any organ, the heart is subject to ultrasound. The doctor performing the procedure sees a real-time video of the beating heart on the screen. Like conventional ultrasound, echocardiography is absolutely painless and has no contraindications. EchoCG may be prescribed if the patient:
- Murmurs in the heart;
- Signs of ventricular failure;
- IHD in chronic or acute form;
- chest trauma;
- Suspicion of aortic aneurysm or other vascular abnormalities, etc.
During echocardiography, a functional diagnostician can establish:
- Condition of all heart valves;
- The dimensions of all chambers of the heart and the thickness of their walls;
- Direction of blood flows and their speed;
- Pressure in the pulmonary artery.
To identify hidden pathologies or abnormalities that are not diagnosed at rest, certain loads can be assigned to the patient during echocardiography. This is called stress echo.
As practice shows, three factors can affect the results of echocardiography:
- Features of the patient, for example, obesity, specific location of the heart, chest deformity, emphysema.
- Experience and qualifications of a functional diagnostician.
- Ultrasound class.
Therefore, only one result of echocardiography does not make final conclusions about the health of the heart and does not make diagnoses. This procedure is usually prescribed in combination with electrocardiography.
conclusions
This article is more of a fact-finding character, because only a cardiologist who has been studying the heart for many years can read an electrocardiogram correctly. Thus, each person will be able to determine whether he has a sinus rhythm, heart rate, compare the duration of the intervals with the norm, and, guided by the proposed algorithm, set the EOS.
But it is worth reminding once again, if you find any abnormalities on your ECG, do not rush to diagnose yourself and take medication - wait for the doctors' opinion.
An electrocardiogram is the most accessible, common way to make a diagnosis, even in conditions of emergency intervention in an ambulance situation.
Now every cardiologist in the field team has a portable and lightweight electrocardiograph capable of reading information by fixing on the recorder the electrical impulses of the heart muscle - myocardium at the time of contraction.
Deciphering the ECG is within the power of every even a child, given the fact that the patient understands the basic canons of the heart. Those same teeth on the tape are the peak (response) of the heart to contraction. The more often they are, the faster the myocardial contraction occurs, the smaller they are, the slower the heartbeat occurs, and in fact the transmission of the nerve impulse. However, this is just a general idea.
To make a correct diagnosis, it is necessary to take into account the time intervals between contractions, the height of the peak value, the age of the patient, the presence or absence of aggravating factors, etc.
An ECG of the heart for diabetics, who, in addition to diabetes, also have late cardiovascular complications, allows us to assess the severity of the disease and intervene in time in order to delay further progression of the disease, which can lead to serious consequences in the form of myocardial infarction, pulmonary embolism and etc.
If the pregnant woman had a bad electrocardiogram, then repeated studies are prescribed with possible daily monitoring.
However, it is worth considering the fact that the values on the tape in a pregnant woman will be somewhat different, since in the process of fetal growth, a natural displacement of the internal organs occurs, which are displaced by the expanding uterus. Their heart occupies a different position in the chest area, therefore, there is a shift in the electrical axis.
In addition, the longer the period, the greater the load experienced by the heart, which is forced to work harder in order to satisfy the needs of two full-fledged organisms.
However, you should not worry so much if the doctor, according to the results, reported the same tachycardia, since it is she who can most often be false, provoked either intentionally or out of ignorance by the patient himself. Therefore, it is extremely important to properly prepare for this study.
In order to correctly pass the analysis, it is necessary to understand that any excitement, excitement and experience will inevitably affect the results. Therefore, it is important to prepare yourself in advance.
Invalid
- Drinking alcohol or any other strong drinks (including energy drinks, etc.)
- Overeating (best taken on an empty stomach or a light snack before going out)
- Smoking
- Use of medicines that stimulate or suppress heart activity, or drinks (such as coffee)
- Physical activity
- Stress
It is not uncommon for a patient, being late to the treatment room at the appointed time, to become very worried or frantically rush to the cherished office, forgetting about everything in the world. As a result, his leaf was mottled with frequent sharp teeth, and the doctor, of course, recommended that his patient re-examine. However, in order not to create unnecessary problems, try to calm yourself as much as possible before entering the cardiology room. Moreover, nothing bad will happen to you there.
When the patient is invited, it is necessary to undress behind the screen to the waist (women take off their bra) and lie down on the couch. In some treatment rooms, depending on the alleged diagnosis, it is also required to free the body from below the torso to the underwear.
After that, the nurse applies a special gel to the abduction sites, to which he attaches electrodes, from which multi-colored wires are stretched to the reading machine.
Thanks to special electrodes, which the nurse places at certain points, the slightest cardiac impulse is captured, which is recorded by means of a recorder.
After each contraction, called depolarization, a tooth is displayed on the tape, and at the moment of transition to a calm state - repolarization, the recorder leaves a straight line.
Within a few minutes, the nurse will take a cardiogram.
The tape itself, as a rule, is not given to patients, but is transferred directly to a cardiologist who deciphers. With notes and transcripts, the tape is sent to the attending physician or transferred to the registry so that the patient can pick up the results himself.
But even if you pick up a cardiogram tape, you will hardly be able to understand what is depicted there. Therefore, we will try to slightly open the veil of secrecy so that you can at least a little bit appreciate the potential of your heart.
ECG interpretation
Even on a blank sheet of this type of functional diagnostics, there are some notes that help the doctor with decoding. The recorder, on the other hand, reflects the transmission of an impulse that passes through all parts of the heart over a certain period of time.
To understand these scribbles, it is necessary to know in what order and how exactly the impulse is transmitted.
The impulse, passing through different parts of the heart, is displayed on the tape in the form of a graph, which conditionally displays marks in the form of Latin letters: P, Q, R, S, T
Let's see what they mean.
P value
The electrical potential, going beyond the sinus node, transmits excitation primarily to the right atrium, in which the sinus node is located.
At this very moment, the reading device will record the change in the form of a peak of excitation of the right atrium. After the conduction system - the interatrial bundle of Bachmann passes into the left atrium. Its activity occurs at the moment when the right atrium is already fully covered by excitation.
On the tape, both of these processes appear as the total value of excitation of both right and left atria and are recorded as a P peak.
In other words, the P peak is a sinus excitation that travels along the conduction pathways from the right to the left atria.
Interval P - Q
Simultaneously with the excitation of the atria, the impulse that has gone beyond the sinus node passes along the lower branch of the Bachmann bundle and enters the atrioventricular junction, which is otherwise called atrioventricular.
This is where the natural delay occurs. Therefore, a straight line appears on the tape, which is called isoelectric.
In evaluating the interval, the time it takes for the impulse to pass through this connection and subsequent departments plays a role.
The count is in seconds.
Complex Q, R, S
After the impulse, passing along the conducting paths in the form of a bundle of His and Purkinje fibers, reaches the ventricles. This whole process is presented on the tape as a QRS complex.
The ventricles of the heart are always excited in a certain sequence, and the impulse travels this path in a certain amount of time, which also plays an important role.
Initially, the septum between the ventricles is covered by excitation. This takes about 0.03 sec. A Q wave appears on the chart, extending just below the main line.
After the impulse for 0.05. sec. reaches the apex of the heart and adjacent areas. A high R wave forms on the tape.
After that, it moves to the base of the heart, which is reflected in the form of a falling S wave. This takes 0.02 seconds.
Thus, the QRS is an entire ventricular complex with a total duration of 0.10 seconds.
S-T interval
Since myocardial cells cannot be in excitation for a long time, there comes a moment of decline when the impulse fades. By this time, the process of restoring the original state that prevailed before the excitement starts.
This process is also recorded on the ECG.
By the way, in this case, the initial role is played by the redistribution of sodium and potassium ions, the movement of which gives this same impulse. All this is called in one word - the process of repolarization.
We will not go into details, but only note that this transition from excitation to extinction is visible from the S to the T wave.
ECG norm
These are the main designations, looking at which one can judge the speed and intensity of the beating of the heart muscle. But in order to get a more complete picture, it is necessary to reduce all the data to some single standard of the ECG norm. Therefore, all devices are configured in such a way that the recorder first draws control signals on the tape, and only then begins to pick up electrical vibrations from the electrodes connected to the person.
Typically, such a signal is equal in height to 10 mm and 1 millivolt (mV). This is the same calibration, control point.
All measurements of the teeth are made in the second lead. On the tape, it is indicated by the Roman numeral II. The R wave must correspond to the control point, and based on it, the rate of the remaining teeth is calculated:
- height T 1/2 (0.5 mV)
- depth S - 1/3 (0.3 mV)
- height P - 1/3 (0.3 mV)
- depth Q - 1/4 (0.2 mV)
The distance between teeth and intervals is calculated in seconds. Ideally, look at the width of the P wave, which is equal to 0.10 sec, and the subsequent length of the teeth and intervals is equal to 0.02 sec each time.
Thus, the width of the P wave is 0.10±0.02 sec. During this time, the impulse will cover both atria with excitation; P - Q: 0.10±0.02 sec; QRS: 0.10±0.02 sec; for passing a full circle (excitation passing from the sinus node through the atrioventricular connection to the atria, ventricles) in 0.30 ± 0.02 sec.
Let's look at a few normal ECGs for different ages (in a child, in adult men and women)
It is very important to take into account the age of the patient, his general complaints and condition, as well as current health problems, since even the slightest cold can affect the results.
Moreover, if a person goes in for sports, then his heart “gets used” to work in a different mode, which affects the final results. An experienced doctor always takes into account all relevant factors.
ECG norm of a teenager (11 years old). For an adult, this will not be the norm.
The norm of the ECG of a young man (age 20 - 30 years).
The description of the resulting diagram is made according to a certain template:
- An assessment of the heart rate is carried out with the measurement of heart rate (heart rate) at the norm: the rhythm is sinus, the heart rate is 60-90 beats per minute.
- Calculation of intervals: Q-T at a rate of 390 - 440 ms.
This is necessary to estimate the duration of the contraction phase (they are called systoles). In this case, Bazett's formula is used. An extended interval indicates coronary heart disease, atherosclerosis, myocarditis, etc. A short interval may be associated with hypercalcemia.
- Assessment of the electrical axis of the heart (EOS)
This parameter is calculated from the isoline, taking into account the height of the teeth. In a normal heart rhythm, the R wave should always be higher than S. If the axis deviates to the right, and S is higher than R, then this indicates disorders in the right ventricle, with a deviation to the left in leads II and III - left ventricular hypertrophy.
- Q-R-S Complex Assessment
Normally, the interval should not exceed 120 ms. If the interval is distorted, then this may indicate various blockades in the conductive pathways (peduncles in the bundles of His) or conduction disturbances in other areas. According to these indicators, hypertrophy of the left or right ventricles can be detected.
- an inventory of the S-T segment is being conducted
It can be used to judge the readiness of the heart muscle to contract after its complete depolarization. This segment should be longer than the Q-R-S complex.
What do Roman numerals on an ECG mean?
Each point to which the electrodes are connected has its own meaning. It captures electrical vibrations and the recorder reflects them on the tape. In order to correctly read the data, it is important to correctly install the electrodes on a specific area.
For example:
- the potential difference between two points of the right and left hand is recorded in the first lead and is denoted by I
- the second lead is responsible for the potential difference between the right arm and left leg - II
- the third between the left hand and left foot - III
If we mentally connect all these points, then we get a triangle, named after the founder of electrocardiography, Einthoven.
In order not to confuse them with each other, all electrodes have wires of different colors: red is attached to the left hand, yellow to the right, green to the left leg, black to the right leg, it acts as a ground.
This arrangement refers to a bipolar lead. It is the most common, but there are also single-pole circuits.
Such a single-pole electrode is indicated by the letter V. The recording electrode, mounted on the right hand, is indicated by the sign VR, on the left, respectively, VL. On the leg - VF (food - leg). The signal from these points is weaker, so it is usually amplified, there is an “a” mark on the tape.
The chest leads are also slightly different. The electrodes are attached directly to the chest. Receiving impulses from these points is the strongest, clearest. They don't require amplification. Here the electrodes are arranged strictly according to the agreed standard:
| designation | electrode attachment point |
| V1 | in the 4th intercostal space at the right edge of the sternum |
| V2 | in the 4th intercostal space at the left edge of the sternum |
| V3 | midway between V2 and V4 |
| V4 | |
| V5 | in the 5th intercostal space on the mid-clavicular line |
| V6 | at the intersection of the horizontal level of the 5th intercostal space and the midaxillary line |
| V7 | at the intersection of the horizontal level of the 5th intercostal space and the posterior axillary line |
| V8 | at the intersection of the horizontal level of the 5th intercostal space and the mid-scapular line |
| V9 | at the intersection of the horizontal level of the 5th intercostal space and the paravertebral line |
The standard study uses 12 leads.
How to identify pathologies in the work of the heart
When answering this question, the doctor pays attention to the diagram of a person and, according to the main designations, he can guess which particular department began to fail.
We will display all the information in the form of a table.
| designation | myocardial department |
| I | anterior wall of the heart |
| II | total display I and III |
| III | posterior wall of the heart |
| aVR | right side wall of the heart |
| aVL | left anterior-lateral wall of the heart |
| aVF | posterior inferior wall of the heart |
| V1 and V2 | right ventricle |
| V3 | interventricular septum |
| V4 | apex of the heart |
| V5 | anterior-lateral wall of the left ventricle |
| V6 | lateral wall of the left ventricle |
Considering all of the above, you can learn how to decipher the tape at least according to the simplest parameters. Although many serious deviations in the work of the heart will be visible to the naked eye, even with this set of knowledge.
For clarity, we will describe some of the most disappointing diagnoses so that you can simply visually compare the norm and deviations from it.
myocardial infarction
Judging by this ECG, the diagnosis will be disappointing. Here, from the positive, only the duration of the Q-R-S interval, which is normal.
In leads V2 - V6 we see ST elevation.
This is the result acute transmural ischemia(AMI) of the anterior wall of the left ventricle. Q waves are seen in the anterior leads.
On this tape, we see a conduction disturbance. However, even with this fact, acute anterior-septal myocardial infarction against the background of blockade of the right leg of the bundle of His.
The right chest leads dismantle the S-T elevation and positive T waves.
Rimm - sinus. Here, there are high regular R waves, the pathology of the Q waves in the posterolateral sections.
Visible deviation ST in I, aVL, V6. All this indicates a posterolateral myocardial infarction with coronary heart disease (CHD).
Thus, the signs of myocardial infarction on the ECG are:
- tall T wave
- elevation or depression of the S-T segment
- pathological Q wave or its absence
Signs of myocardial hypertrophy
Ventricular
For the most part, hypertrophy is characteristic of those people whose heart has experienced additional stress for a long time as a result of, say, obesity, pregnancy, some other disease that negatively affects the non-vascular activity of the whole organism as a whole or individual organs (in particular, lungs, kidneys).
The hypertrophied myocardium is characterized by several signs, one of which is an increase in the time of internal deflection.
What does it mean?
Excitation will have to spend more time passing through the cardiac departments.
The same applies to the vector, which is also larger, longer.
If you look for these signs on the tape, then the R wave will be higher in amplitude than normal.
A characteristic symptom is ischemia, which is the result of insufficient blood supply.
Through the coronary arteries to the heart there is a blood flow, which, with an increase in the thickness of the myocardium, encounters an obstacle on the way and slows down. Violation of the blood supply causes ischemia of the subendocardial layers of the heart.
Based on this, the natural, normal function of the pathways is disrupted. Inadequate conduction leads to failures in the process of excitation of the ventricles.
After that, a chain reaction is launched, because the work of other departments depends on the work of one department. If there is hypertrophy of one of the ventricles on the face, then its mass increases due to the growth of cardiomyocytes - these are cells that are involved in the process of transmitting a nerve impulse. Therefore, its vector will be larger than the vector of a healthy ventricle. On the tape of the electrocardiogram, it will be noticeable that the vector will be deviated towards the localization of hypertrophy with a shift in the electrical axis of the heart.
The main features include a change in the third chest lead (V3), which is something like a transshipment, transition zone.
What kind of zone is this?
It includes the height of the R tooth and the depth S, which are equal in their absolute value. But when the electrical axis changes as a result of hypertrophy, their ratio will change.
Consider specific examples
In sinus rhythm, left ventricular hypertrophy is clearly visible with characteristic high T waves in the chest leads.
There is nonspecific ST depression in the inferolateral region.
EOS (electrical axis of the heart) deviated to the left with an anterior hemiblock and prolongation of the QT interval.
High T waves indicate that a person has, in addition to hypertrophy, also hyperkalemia most likely developed against the background of renal failure and, which are characteristic of many patients who have been ill for many years.
In addition, a longer QT interval with ST depression indicates hypocalcemia that progresses in advanced stages (chronic renal failure).
This ECG corresponds to an elderly person who has serious kidney problems. He is on the edge.
atrial
As you already know, the total value of atrial excitation on the cardiogram is shown by the P wave. In case of failures in this system, the width and / or height of the peak increases.
With right atrial hypertrophy (RAA), P will be higher than normal, but not wider, since the peak of the excitation of the PP ends before the excitation of the left. In some cases, the peak takes on a pointed shape.
With HLP, there is an increase in the width (more than 0.12 seconds) and height of the peak (double-hump appears).
These signs indicate a violation of the conduction of the impulse, which is called intra-atrial blockade.
blockades
Blockades are understood as any failures in the conduction system of the heart.
A little earlier, we looked at the path of the impulse from the sinus node through the conducting paths to the atria, at the same time, the sinus impulse rushes along the lower branch of the Bachmann bundle and reaches the atrioventricular junction, passing through it, it undergoes a natural delay. Then it enters the conduction system of the ventricles, presented in the form of His bundles.
Depending on the level at which the failure occurred, a violation is distinguished:
- intra-atrial conduction (sinus impulse block in the atria)
- atrioventricular
- intraventricular
Intraventricular conduction
This system is presented in the form of a trunk of His, divided into two branches - the left and right legs.
The right leg "supplies" the right ventricle, inside which it branches into many small networks. It appears as one wide bundle with branches inside the muscles of the ventricle.
The left leg is divided into anterior and posterior branches, which "adjoin" the anterior and posterior wall of the left ventricle. Both of these branches form a network of smaller branches within the LV musculature. They are called Purkinje fibers.
Blockade of the right leg of the bundle of His
The course of the impulse first covers the path through the excitation of the interventricular septum, and then the first unblocked LV is involved in the process, through its normal course, and only after that the right one is excited, to which the impulse reaches the distorted path through the Purkinje fibers.
Of course, all this will affect the structure and shape of the QRS complex in the right chest leads V1 and V2. At the same time, on the ECG we will see bifurcated peaks of the complex, similar to the letter "M", in which R is the excitation of the interventricular septum, and the second R1 is the actual excitation of the pancreas. S, as before, will be responsible for the excitation of the left ventricle.
On this tape we see incomplete RBBB and 1st degree AB block, there are also p ubtsovye changes in the posterior diaphragmatic region.
Thus, the signs of blockade of the right leg of the bundle of His are as follows:
- elongation of the QRS complex in standard lead II for more than 0.12 sec.
- an increase in the time of internal deflection of the right ventricle (on the graph above, this parameter is presented as J, which is more than 0.02 sec in the right chest leads V1, V2)
- deformation and splitting of the complex into two "humps"
- negative T wave
Blockade of the left leg of the bundle of His
The course of excitation is similar, the impulse reaches the LV through detours (it does not pass along the left leg of the His bundle, but through the network of Purkinje fibers from the pancreas).
Characteristic features of this phenomenon on the ECG:
- widening of the ventricular QRS complex (more than 0.12 sec)
- an increase in the time of internal deviation in the blocked LV (J is greater than 0.05 sec)
- deformation and bifurcation of the complex in leads V5, V6
- negative T wave (-TV5, -TV6)
Blockade (incomplete) of the left leg of the bundle of His
It is worth paying attention to the fact that the S wave will be “atrophied”, i.e. he will not be able to reach the isoline.
Atrioventricular block
There are several degrees:
- I - slow conduction is characteristic (heart rate is normal within 60 - 90; all P waves are associated with the QRS complex; P-Q interval is more than normal 0.12 sec.)
- II - incomplete, divided into three options: Mobitz 1 (heart rate slows down; not all P waves are associated with the QRS complex; the P-Q interval changes; periodicals appear 4:3, 5:4, etc.), Mobitz 2 (also most, but the interval P - Q is constant; periodicity 2:1, 3:1), high-grade (significantly reduced heart rate; periodicity: 4:1, 5:1; 6:1)
- III - complete, divided into two options: proximal and distal
Well, we will go into details, but only note the most important:
- the time of passage through the atrioventricular junction is normally 0.10±0.02. Total, no more than 0.12 sec.
- reflected on the interval P - Q
- here there is a physiological impulse delay, which is important for normal hemodynamics
AV block II degree Mobitz II
Such violations lead to failures of intraventricular conduction. Usually people with such a tape have shortness of breath, dizziness, or they quickly overwork. In general, this is not so scary and is very common even among relatively healthy people who do not particularly complain about their health.
Rhythm disturbance
Signs of arrhythmia are usually visible to the naked eye.
When excitability is disturbed, the response time of the myocardium to the impulse changes, which creates characteristic graphs on the tape. Moreover, it should be understood that not in all cardiac departments the rhythm can be constant, taking into account the fact that there is, say, some kind of blockade that inhibits the transmission of impulses and distorts signals.
So, for example, the following cardiogram indicates atrial tachycardia, and the one below it indicates ventricular tachycardia with a frequency of 170 beats per minute (LV).
The sinus rhythm with a characteristic sequence and frequency is correct. Its characteristics are as follows:
- frequency of P waves in the range of 60-90 per minute
- RR spacing is the same
- the P wave is positive in the II standard lead
- P wave is negative in lead aVR
Any arrhythmia indicates that the heart is working in a different mode, which cannot be called regular, habitual and optimal. The most important thing in determining the correctness of the rhythm is the uniformity of the interval of the P-P waves. Sinus rhythm is correct when this condition is met.
If there is a slight difference in the intervals (even 0.04 sec, not exceeding 0.12 sec), then the doctor will already indicate a deviation.
The rhythm is sinus, irregular, since the RR intervals differ by no more than 0.12 sec.
If the intervals are more than 0.12 seconds, then this indicates an arrhythmia. It includes:
- extrasystole (most common)
- paroxysmal tachycardia
- flicker
- flutter, etc.
Arrhythmia has its own focus of localization, when a rhythm disturbance occurs in certain parts of the heart (in the atria, ventricles) on the cardiogram.
The most striking sign of atrial flutter is high-frequency impulses (250 - 370 beats per minute). They are so strong that they overlap the frequency of sinus impulses. There will be no P waves on the ECG. In their place, sharp, sawtooth low-amplitude “teeth” (no more than 0.2 mV) will be visible on lead aVF.
ECG Holter
This method is otherwise abbreviated as HM ECG.
What it is?
Its advantage is that it is possible to carry out daily monitoring of the work of the heart muscle. The reader itself (recorder) is compact. It is used as a portable device capable of recording signals from electrodes on a magnetic tape for a long period of time.
On a conventional stationary device, it is quite difficult to notice some intermittent jumps and malfunctions in the work of the myocardium (given the asymptomaticity) and the Holter method is used to make sure the diagnosis is correct.
The patient is invited to keep a detailed diary on his own after medical instructions, since some pathologies can manifest themselves at a certain time (the heart “collapses” only in the evenings and then not always, in the mornings something “presses” on the heart).
While observing, a person writes down everything that happens to him, for example: when he was at rest (sleep), overworked, ran, quickened his pace, worked physically or mentally, was nervous, worried. At the same time, it is also important to listen to yourself and try to describe as clearly as possible all your feelings, symptoms that accompany certain actions, events.
The time of data collection usually lasts no longer than a day. For such daily monitoring of the ECG allows you to get a clearer picture and determine the diagnosis. But sometimes the data collection time can be extended to several days. It all depends on the person's well-being and the quality and completeness of previous laboratory tests.
Usually, the basis for prescribing this type of analysis is the painless symptoms of coronary heart disease, latent hypertension, when doctors have suspicions, doubts about any diagnostic data. In addition, they can prescribe it when prescribing new drugs for the patient that affect the functioning of the myocardium, which are used in the treatment of ischemia or if there is an artificial pacemaker, etc. This is also done in order to assess the patient's condition in order to assess the degree of effectiveness of the prescribed therapy, and so on.
How to prepare for HM ECG
Usually there is nothing complicated in this process. However, it should be understood that other devices, especially emitting electromagnetic waves, can affect the device.
Interaction with any metal is also not desirable (rings, earrings, metal buckles, etc. should be removed). The device must be protected from moisture (complete body hygiene under the shower or bath is unacceptable).
Synthetic fabrics also negatively affect the results, as they can create static voltage (they become electrified). Any such “splash” from clothes, bedspreads and other things distorts the data. Replace them with natural ones: cotton, linen.
The device is extremely vulnerable and sensitive to magnets, do not stand near a microwave oven or an induction hob, avoid being near high-voltage wires (even if you drive a car through a small section of the road over which high-voltage lines lie).
How is data collected?
Usually, the patient is given a referral, and at the appointed time he comes to the hospital, where the doctor, after some theoretical introductory course, installs electrodes on certain parts of the body, which are connected by wires to a compact recorder.
The registrar itself is a small device that captures any electromagnetic vibrations and remembers them. It fastens on the belt and hides under the clothes.
Men sometimes have to shave in advance some parts of the body on which the electrodes are attached (for example, to “free” the chest from hair).
After all preparations and installation of equipment, the patient can go about his usual activities. He should merge into his daily life as if nothing had happened, though not forgetting to take notes (it is extremely important to indicate the time of manifestation of certain symptoms and events).
After the period set by the doctor, the “subject” returns to the hospital. The electrodes are removed from it and the reading device is taken away.
The cardiologist, using a special program, will process the data from the recorder, which, as a rule, is easily synchronized with a PC and will be able to make a specific inventory of all the results obtained.
Such a method of functional diagnostics as an ECG is much more effective, since thanks to it even the slightest pathological changes in the work of the heart can be noticed, and it is widely used in medical practice in order to identify life-threatening diseases in patients like a heart attack.
It is especially important for diabetics with cardiovascular late complications that have developed against the background of diabetes mellitus to undergo it periodically at least once a year.
If you find an error, please select a piece of text and press Ctrl+Enter.
ECG interpretation is performed by a qualified specialist. This method of functional diagnostics checks:
- Heart rate: what is the state of the generators of the electrical impulse and the cardiac systems that conduct these impulses.
- Cardiac muscle: its condition and performance, damage, inflammation and other pathological processes that could affect the condition of the heart.
- ECG control;
- Holter (monitoring of the work of the heart throughout the day);
- Ultrasound of the heart muscle;
- Treadmill (a test for the performance of the heart during exercise).
- functional (manifested against the background of panic and nerves);
- organic (if a person has heart defects, myocarditis and congenital problems with the cardiovascular system).
- 1. Isolated cases of manifestation of the disease up to 60 times every hour, united by one focus (monotopic).
- 2. Constant monotopic changes, manifested in an amount of more than 5-6 times every minute.
- 3. Permanent polymorphic (have a different shape) and polytopic (have a different focus of occurrence) changes.
- 4. Paired or group, accompanied by episodic attacks of paroxysmal tachycardia.
- 5. Early manifestation of extrasystoles.
- 1. Sinoatrial blockade: the passage of the impulse directly from the sinus node is difficult. Then this blockade develops into a syndrome of weakness of the sinus node, leads to a decrease in the number of contractions until a new blockade, disruption of the blood supply to the peripheral section, shortness of breath, weakness, dizziness and loss of consciousness.
- 2. Blockade of Samoilov-Wenckebach - the second degree of the sinoatrial blockade.
- 3. Atrioventricular block is delayed excitation of the atrioventricular node for more than 0.09 seconds. There are 3 degrees of blockade of this type. At the highest degree of the disease, the ventricles are more likely to contract. Therefore, in the highest stages, circulatory disturbances become more severe.
Show all
Heartbeat
Patients collect the electrocardiogram along with its results. It cannot be decrypted by itself. To read the diagram, you will need a special medical education. No need to be nervous before meeting with a functional diagnostician. At the appointment, he will tell you all the risks of the diagnosis, prescribing an effective treatment. But if the patient is diagnosed with a serious illness, then a consultation with a cardiologist will be required.
When the decoding of the ECG did not give clear results, the doctor may prescribe additional studies:
The results of measurements using these studies are an accurate indicator of the work of the heart. If there are no failures in the work of the myocardium, the tests will have good results.
On the ECG of a healthy person, the inscription "Sinus rhythm" is found. If the frequency of beats per minute up to 90 is added to this inscription, the results are good, the heart works without interruption. Sinus rhythm is a measure of the rhythm of the sinus node, which is the main rhythm producer for regulating and generating electrical impulses with which the heart muscle contracts. The description of the electrocardiogram, which includes sinus rhythm, is the norm, indicating the health of the sinus node and the heart muscle itself.
If the cardiogram of the heart does not have any other notes in its description, it indicates the overall health of the heart. Sinus rhythm can be replaced by atrial, atrioventricular or ventricular. These types of rhythms indicate that contractions are carried out precisely by these parts of the heart, which is considered a pathology.
What is a lipidogram and lipid spectrum of blood - decoding of the analysis
What is sinus arrhythmia?
Sinus arrhythmia is a common diagnosis in childhood and adolescence. It is characterized by different time intervals between sinus contractions of the heart muscle. Experts say that this pathology can be caused by changes at the physiological level. Up to 40% of sinus arrhythmias should be monitored by a cardiologist. Patients should be examined and re-examined every 3-4 months. Such precautions will protect you as much as possible from the development of more serious heart diseases.
Sinus bradycardia is the rhythm of heart contractions up to 50 times per minute. This phenomenon is also possible in healthy people during sleep or in professional athletes. Pathological bradycardia may be a sign of sick sinus syndrome. This case implies a severe bradycardia, reaching up to 35 heartbeats per minute. You can observe such a pathology all the time, and not just at night.
If bradycardia consists of pauses between contractions of up to 3 seconds during the day and up to 5 seconds at night, there may be a violation of the supply of oxygen to the tissues, which usually leads to fainting. Only a pacemaker of electrical origin, which is placed directly on the heart during surgery, will help get rid of this problem. The installation takes place at the site of the sinus node, which further allows the heart to work without failures.
Causes of a poor cardiogram may be related to sinus tachycardia, which is a heart rate contraction of more than 90 times per minute. It is divided into physiological and pathological tachycardia. Healthy people may experience sinus tachycardia during physical and emotional stress, drinking coffee or strong tea, alcohol-containing drinks and energy drinks. Sinus tachycardia after active pastime is a brief manifestation. After the manifestation of an increased number of strokes, the rhythm returns to its normal state in a fairly short time after a decrease in the intensity of physical activity.
With pathological tachycardia, a rapid heartbeat worries the patient all the time. The cause of increased heart rate can be: fever, infection, blood loss, dehydration, anemia, and more. Treat the underlying cause causing tachycardia. Relief of sinus tachycardia occurs only in the case of myocardial infarction or acute coronary syndrome.
How is extrasystole manifested?
The specialist can determine this pathology immediately, since this is a change in rhythm, the nature of which is the foci behind the sinus rhythm. They give extra contractions of the heart muscle. After this process, a pause doubled in time appears, the name of which is compensatory. Patients believe that such a change in the heartbeat occurs on the basis of nervous stress. Rhythm can be both rapid and slow, sometimes chaotic. The patient himself can notice the dips that occur in the rhythm of the heartbeat.
An example of deciphering an ECG with extrasystole is an example with a pathology that is visible even to non-specialists. Some patients complain not only of changes in rhythm, but also of unpleasant and painful sensations in the chest area. They experience jolts, tingling, a constricting feeling of fear rising in the abdomen.
Such manifestations are not always pathological and life-threatening.
Many types of extrasystoles do not depress blood circulation and do not reduce the efficiency of the heart.
Extrasystoles are divided into 2 types:
In 20% of cases, the cause of the disease is intoxication or surgery in the heart area. A single manifestation of extrasystole occurs rarely (up to 5 times in 1 hour). Such dips are functional in nature, they are not an obstacle to normal blood supply. There are times when paired extrasystoles occur. They appear after a series of normal contractions. It is this rhythm that is an obstacle to the normal functioning of the heart muscle. For an accurate diagnosis of this manifestation, an additional ECG analysis and Holter are prescribed with a setting for a day.
The main classes of pathology
Extrasystoles also have the appearance of allorhythmia. When an extrasystole appears on every second contraction, specialists diagnose bigeminia, on every third - trigeminia, on every fourth - quadrigeminia. According to Laum's classification, ventricular extrasystoles are divided into 5 classes depending on the daily examination indicators:
For treatment, medications are not prescribed. With the manifestation of the disease less than 200 times a day (Holter monitoring will help to establish the exact number), extrasystoles are considered safe, so you should not worry about their manifestations. Regular examinations by a cardiologist every 3 months are required.
If the patient's electrocardiogram revealed pathological contractions more than 200 times every day, then additional examinations are prescribed. Specialists prescribe ultrasound of the heart and magnetic resonance imaging (MRI) of the heart muscle. The treatment of the manifestation is specific and requires a special approach, since it is not extrasystoles that are treated, but the root causes of their occurrence.
Paroxysmal tachycardia
Paroxysm is a manifestation of an attack. A similar process of increased heart rate can last for several hours or several days. The electrocardiogram displays the same intervals between muscle contractions. But the rhythm changes and can reach more than 100 beats in 1 minute (the average is 120-250 times).
Doctors distinguish supraventricular and ventricular types of tachycardia. The basis of this pathology lies in the abnormal circulation of an electrical impulse in the cardiovascular system. You can get rid of this manifestation at home, but for a while: you need to hold your breath, start coughing angrily or dip your face in cold water. But such methods are ineffective. Therefore, there is a medical method for the treatment of paroxysmal tachycardia.
One of the varieties of supraventricular tachycardia is Wolff-Parkinson-White syndrome. The title includes the names of all the doctors who described it. The reason for this type of tachycardia is the appearance between the atria and ventricles of an extra bundle of nerves that conducts the rhythm faster than the main driver. As a result - the occurrence of one extra time of contraction of the heart. Such a pathology can be cured conservatively or surgically. The operation is prescribed only in case of low efficiency or allergy in the patient to the active components of the treatment, with atrial fibrillation or heart defects of a different nature.
Clerk-Levy-Christesco syndrome is a manifestation similar to the previous pathology, but it is characterized by an earlier than normal stimulation of the ventricles with the help of an additional bundle through which the nerve impulse passes. The syndrome is a congenital pathology. If you decipher the cardiogram of the heart, its manifestation can be seen immediately by attacks of rapid heartbeat.
Atrial fibrillation
During fibrillation, irregular contractions of the heart muscle are observed with intervals of varying length between contractions. This is explained by the fact that the rhythm is not set by the sinus node, but by other cells of the atria. The frequency of contractions can even reach 700 beats in 1 minute. A full-fledged atrial contraction is simply absent, it falls on muscle fibers that do not allow the ventricles to be completely filled with blood. The consequence of this process is the deterioration of the ejection of blood by the heart, which leads to oxygen starvation of organs and tissues of all body systems.
Atrial fibrillation has another name: atrial fibrillation. In fact, not all atrial contractions go directly to the ventricles. This results in a decrease in the normal heart rate (bradysystole, which has a rate of less than 60 beats per minute). But the contraction of the heart can be normal (normosystole, 60-90 times per minute) and increased (tachysystole, more than 90 times per minute).
Determining atrial fibrillation on an electrocardiogram is easy, since attacks are difficult to miss. The beginning of an attack in 90% of cases is a strong push of the heart muscle. Then there is the development of a series of non-rhythmic fluctuations of the heart with an increased or normal frequency. The patient's condition also worsens: he becomes weak, sweaty, dizzy. The patient wakes up with a pronounced fear of death. There may be shortness of breath and an excited state. Sometimes there is a loss of consciousness. It is also easy to read the cardiogram at the final stage of the attack: the rhythm returns to normal. But the patient feels a strong desire to urinate, during which a sufficiently large amount of fluid comes out.
The relief of the disease is carried out using reflex methods, drugs in the form of tablets or injections. Less commonly, specialists perform cardioversion - stimulation of the heart muscle using an electric defibrillator. If attacks of ventricular fibrillation are not eliminated within 2 days, complications may occur. Pulmonary embolism, stroke may occur.
A constant form of flicker, in which neither medication nor electrical stimulation of the heart helps, becomes commonplace in the patient's life and is felt only during tachysystole (increased heart rate). If the electrocardiogram revealed tachysystole and atrial fibrillation, then it is necessary to reduce the number of heart contractions to normal without trying to make them rhythmic. Atrial fibrillation can appear against the background of coronary heart disease, thyrotoxicosis, heart defects of various nature, diabetes mellitus, sick sinus syndrome, intoxication after alcohol poisoning.
atrial flutter
Atrial flutter - constant and frequent contractions of the atria (more than 200 times per minute) and ventricles (less than 200 times). Flutter in 90% of cases has an acute form, but it is much better tolerated and easier than fibrillation, since changes in blood circulation are less pronounced. The development of flutter is possible against the background of heart disease (cardiomyopathy, heart failure), after surgery on the heart muscle. With obstructive pulmonary disease, it practically does not manifest itself. Reading an ECG with this disease is easy, as it is manifested by frequent rhythmic heartbeats, swollen veins in the neck, shortness of breath, increased sweating and weakness.
In the normal state, an electrical excitation is formed in the sinus node, which passes through the conducting system. It experiences a delay of a physiological nature for literally a fraction of a second in the region of the atrioventricular node. The atria and ventricles, whose function is to pump blood, are stimulated by this impulse. If the impulse is delayed in some part of the system, it reaches other areas of the heart later, which leads to disturbances in the normal operation of the pumping system. Changes in conduction are called blockade.
The occurrence of blockades is a functional disorder. But the reason for their occurrence in 75% of cases is alcohol or drug intoxication and organic diseases of the heart muscle. There are several types of blockades:
Conduction disorders in the ventricles
The electrical signal travels inside the ventricles to special cells made of muscle tissue. The propagation of this signal is carried out through systems such as the bundle of His, its legs and their branches. The cause of a bad cardiogram is the occurrence of disturbances in the conduction of an electrical signal. Specialists easily diagnose this deviation from the norm on the ECG. At the same time, the diagram clearly shows that one of the ventricles is stimulated later than the second, because the signaling is made with a delay, passing along bypass routes due to blockade of the desired area.
The blockade is classified not only by the place of occurrence, but also by type. There are complete and incomplete blockades, permanent and non-permanent. The root causes of blockades inside the ventricles are the same as in other diseases with poor conductivity: ischemic disease, cardiomyopathy, defects of a different nature, fibrosis, cancers in the heart. The consumption of antiarrhythmic drugs, an increase in the level of potassium in the blood, oxygen starvation, and more can affect the occurrence of the disease.
Most often there is a blockage of the upper branch on the left leg of the bundle of His. The second place is occupied by the blockade of the entire area of the right leg. It does not occur on the basis of other heart diseases. The blockade of the left leg occurs with myocardial lesions in a number of diseases. The lower branch of the left leg suffers from pathological changes in the structure of the human chest. It can also occur when overloading the right ventricle.
Thanks
The site provides reference information for informational purposes only. Diagnosis and treatment of diseases should be carried out under the supervision of a specialist. All drugs have contraindications. Expert advice is required!
Electrocardiogram is a widely used method of objective diagnostics various pathologies of the human heart, which is used today almost everywhere. An electrocardiogram (ECG) is taken in a clinic, in an ambulance, or in a hospital department. An ECG is a very important recording that reflects the condition of the heart. That is why the reflection of a variety of options for cardiac pathology on the ECG is described by a separate science - electrocardiography. Electrocardiography also deals with the problems of correct ECG recording, decoding issues, interpretation of controversial and unclear points, etc.Definition and essence of the method
An electrocardiogram is a record of the work of the heart, which is represented as a curved line on paper. The cardiogram line itself is not chaotic, it has certain intervals, teeth and segments that correspond to certain stages of the heart.To understand the essence of the electrocardiogram, you need to know what exactly the device called the electrocardiograph records. The ECG records the electrical activity of the heart, which changes cyclically, in accordance with the onset of diastole and systole. The electrical activity of the human heart may seem like a fantasy, but this unique biological phenomenon exists in reality. In reality, there are so-called cells of the conduction system in the heart, which generate electrical impulses that are transmitted to the muscles of the organ. It is these electrical impulses that cause the myocardium to contract and relax with a certain rhythm and frequency.
An electrical impulse propagates through the cells of the conduction system of the heart in a strictly sequential manner, causing contraction and relaxation of the corresponding departments - the ventricles and atria. The electrocardiogram reflects exactly the total electrical potential difference in the heart.
decoding?
An electrocardiogram can be taken at any clinic or general hospital. You can contact a private medical center where there is a specialist cardiologist or therapist. After recording the cardiogram, the tape with curves is examined by the doctor. It is he who analyzes the recording, deciphers it and writes the final conclusion, which reflects all visible pathologies and functional deviations from the norm. An electrocardiogram is recorded using a special device - an electrocardiograph, which can be multi-channel or single-channel. The ECG recording speed depends on the modification and modernity of the device. Modern devices can be connected to a computer, which, if there is a special program, will analyze the recording and issue a ready-made conclusion immediately after the procedure is completed.
Any cardiograph has special electrodes that are applied in a strictly defined order. There are four clothespins in red, yellow, green and black, which are placed on both hands and both legs. If you go in a circle, then the clothespins are applied according to the "red-yellow-green-black" rule, from the right hand. Remembering this sequence is easy thanks to the student saying: "Every-Woman-Worst-Hell." In addition to these electrodes, there are also chest electrodes, which are installed in the intercostal spaces.
As a result, the electrocardiogram consists of twelve curves, six of which are recorded from chest electrodes, and are called chest leads. The remaining six leads are recorded from electrodes attached to the arms and legs, with three of them called standard and three more reinforced. The chest leads are designated V1, V2, V3, V4, V5, V6, the standard ones are simply Roman numerals - I, II, III, and the reinforced leg leads are the letters aVL, aVR, aVF. Different leads of the cardiogram are necessary to create the most complete picture of the activity of the heart, since some pathologies are visible on the chest leads, others on the standard leads, and still others on the enhanced ones.
The person lies down on the couch, the doctor fixes the electrodes and turns on the device. While the ECG is being written, the person should be absolutely calm. We must not allow the appearance of any stimuli that can distort the true picture of the work of the heart.
How to make an electrocardiogram with the subsequent
decoding - video
The principle of decoding the ECG
Since the electrocardiogram reflects the processes of contraction and relaxation of the myocardium, it is possible to trace how these processes proceed and to identify the existing pathological processes. The elements of the electrocardiogram are closely related, and reflect the duration of the phases of the cardiac cycle - systole and diastole, that is, contraction and subsequent relaxation. The interpretation of the electrocardiogram is based on the study of the teeth, from the position relative to each other, duration, and other parameters. For analysis, the following elements of the electrocardiogram are studied:1. teeth.
2. intervals.
3. Segments.
All sharp and smooth bulges and concavities on the ECG line are called teeth. Each tooth is designated by a letter of the Latin alphabet. The P wave reflects the contraction of the atria, the QRS complex - the contraction of the ventricles of the heart, the T wave - the relaxation of the ventricles. Sometimes after the T wave on the electrocardiogram there is another U wave, but it does not have a clinical and diagnostic role.
An ECG segment is a segment enclosed between adjacent teeth. For the diagnosis of heart pathology, the P-Q and S-T segments are of great importance. The interval on the electrocardiogram is a complex that includes a wave and an interval. The P-Q and Q-T intervals are of great importance for diagnosis.
Often in the conclusion of a doctor you can see small Latin letters, which also denote teeth, intervals and segments. Small letters are used if the prong is less than 5 mm long. In addition, several R-waves may appear in the QRS complex, which are commonly referred to as R ’, R ”, etc. Sometimes the R wave is simply missing. Then the whole complex is denoted by only two letters - QS. All this is of great diagnostic value.
ECG interpretation plan - a general scheme for reading the results
When deciphering the electrocardiogram, the following parameters are required to reflect the work of the heart: - the position of the electrical axis of the heart;
- determination of the correctness of the heart rhythm and the conductivity of the electrical impulse (blockades, arrhythmias are detected);
- determination of the regularity of contractions of the heart muscle;
- determination of heart rate;
- identification of the source of the electrical impulse (determine whether the rhythm is sinus or not);
- analysis of the duration, depth and width of the atrial P wave and the P-Q interval;
- analysis of the duration, depth, width of the complex of teeth of the ventricles of the heart QRST;
- analysis of the parameters of the RS-T segment and the T wave;
- analysis of the parameters of the interval Q - T.
In the conclusion on the electrocardiogram, the doctor must necessarily reflect the following parameters:
- sinus rhythm or not;
- rhythm regularity;
- heart rate (HR);
- position of the electrical axis of the heart.
An example of decoding an electrocardiogram
At the very beginning of the electrocardiogram tape there should be a calibration signal, which looks like a capital letter "P" 10 mm high. If this calibration signal is absent, then the electrocardiogram is uninformative. If the height of the calibration signal is below 5 mm in standard and enhanced leads, and below 8 mm in the chest leads, then the electrocardiogram voltage is low, which is a sign of a number of heart pathologies. For the subsequent decoding and calculation of some parameters, it is necessary to know how much time fits into one cell of graph paper. At a tape speed of 25 mm / s, one cell 1 mm long is 0.04 seconds, and at a speed of 50 mm / s - 0.02 seconds.Checking the regularity of heart beats
It is estimated by intervals R - R. If the teeth are located at the same distance from each other throughout the entire recording, then the rhythm is regular. Otherwise, it is called correct. Estimating the distance between the R-R waves is very simple: the electrocardiogram is recorded on graph paper, which makes it easy to measure any gaps in millimeters.Calculation of heart rate (HR)
It is carried out by a simple arithmetic method: they count the number of large squares on graph paper that fit between two R teeth. Then the heart rate is calculated by the formula, which is determined by the speed of the tape in the cardiograph: 1. The belt speed is 50 mm/s - then the heart rate is 600 divided by the number of squares.
2. The belt speed is 25 mm/s - then the heart rate is 300 divided by the number of squares.
For example, if 4.8 large squares fit between two R teeth, then the heart rate, at a tape speed of 50 mm / s, will be 600 / 4.8 = 125 beats per minute.
If the rhythm of heart contractions is incorrect, then the maximum and minimum heart rates are determined, taking as a basis also the maximum and minimum distances between the R waves.
Finding the Source of the Rhythm
The doctor studies the rhythm of heart contractions and finds out which node of nerve cells causes cyclic processes of contractions and relaxations of the heart muscle. This is very important for determining blockades.ECG interpretation - rhythms
Normally, the sinus ganglion is the pacemaker. And such a normal rhythm itself is called sinus - all other options are pathological. In various pathologies, any other node of the nerve cells of the conduction system of the heart can act as a pacemaker. In this case, cyclic electrical impulses are confused, and the rhythm of heart contractions is disturbed - an arrhythmia occurs.In sinus rhythm on the electrocardiogram in lead II, there is a P wave in front of each QRS complex, and it is always positive. On one lead, all P waves should have the same shape, length and width.
With atrial rhythm the P wave in the II and III leads is negative, but is present in front of each QRS complex.
Atrioventricular rhythms characterized by the absence of P waves on cardiograms, or the appearance of this wave after the QRS complex, and not before it, as is normal. With this type of rhythm, the heart rate is low, ranging from 40 to 60 beats per minute.
Ventricular rhythm characterized by an increase in the width of the QRS complex, which becomes large and rather intimidating. The P waves and the QRS complex are completely unrelated to each other. That is, there is no strict correct normal sequence - the P wave, followed by the QRS complex. The ventricular rhythm is characterized by a decrease in heart rate - less than 40 beats per minute.
Identification of the pathology of the conduction of an electrical impulse in the structures of the heart
To do this, measure the duration of the P wave, the P-Q interval and the QRS complex. The duration of these parameters is calculated from the millimetric tape on which the cardiogram is recorded. First, consider how many millimeters each tooth or interval occupies, after which the resulting value is multiplied by 0.02 at a writing speed of 50 mm / s, or by 0.04 at a writing speed of 25 mm / s.The normal duration of the P wave is up to 0.1 seconds, the P-Q interval is 0.12-0.2 seconds, the QRS complex is 0.06-0.1 seconds.
Electrical axis of the heart
Referred to as angle alpha. It can have a normal position, horizontal or vertical. Moreover, in a thin person, the axis of the heart is more vertical relative to the average values, and in full people it is more horizontal. The normal position of the electrical axis of the heart is 30-69 o , vertical - 70-90 o , horizontal - 0-29 o . Angle alpha, equal to from 91 to ±180 o reflects a sharp deviation of the electrical axis of the heart to the right. Angle alpha, equal to from 0 to -90 o , reflects a sharp deviation of the electrical axis of the heart to the left. The electrical axis of the heart can deviate in various pathological conditions. For example, hypertension leads to a deviation to the right, a conduction disorder (blockade) can shift it to the right or to the left.
Atrial P wave
The atrial P wave should be:- positive in I, II, aVF and chest leads (2, 3, 4, 5, 6);
- negative in aVR;
- biphasic (part of the tooth lies in the positive region, and part - in the negative) in III, aVL, V1.
Pathological forms of the P wave may indicate the following pathologies:
1.
High and sharp teeth in II, III, aVF leads appear with hypertrophy of the right atrium ("cor pulmonale");
2.
The P wave with two peaks with a large width in I, aVL, V5 and V6 leads indicates left atrial hypertrophy (for example, mitral valve disease).
P–Q interval
The P–Q interval has a normal duration of 0.12 to 0.2 seconds. An increase in the duration of the P-Q interval is a reflection of atrioventricular block. On the electrocardiogram, three degrees of atrioventricular (AV) blockade can be distinguished:- I degree: simple prolongation of the P-Q interval with the preservation of all other complexes and teeth.
- II degree: prolongation of the P-Q interval with partial loss of some QRS complexes.
- III degree: lack of communication between the P wave and QRS complexes. In this case, the atria work in their own rhythm, and the ventricles in their own.
Ventricular QRST complex
The ventricular QRST-complex consists of the QRS-complex itself and the S-T segment. The normal duration of the QRST-complex does not exceed 0.1 seconds, and its increase is detected with blockades of the Hiss bundle legs. QRS complex consists of three teeth, respectively Q, R and S. The Q wave is visible on the cardiogram in all leads except 1, 2 and 3 chest. A normal Q wave has an amplitude up to 25% of that of an R wave. The duration of the Q wave is 0.03 seconds. The R wave is recorded in absolutely all leads. The S wave is also visible in all leads, but its amplitude decreases from the 1st chest to the 4th, and in the 5th and 6th it may be completely absent. The maximum amplitude of this tooth is 20 mm.
The S–T segment is very important from a diagnostic point of view. It is by this tooth that one can detect myocardial ischemia, that is, a lack of oxygen in the heart muscle. Usually this segment runs along the isoline, in 1, 2 and 3 chest leads, it can rise up to a maximum of 2 mm. And in the 4th, 5th and 6th chest leads, the S-T segment can shift below the isoline by a maximum of half a millimeter. It is the deviation of the segment from the isoline that reflects the presence of myocardial ischemia.
T wave
The T wave is a reflection of the process of eventual relaxation in the cardiac muscle of the ventricles of the heart. Usually with a large amplitude of the R wave, the T wave will also be positive. Negative T wave is recorded normally only in lead aVR.Q-T interval
The Q - T interval reflects the process of ultimately contracting in the myocardium of the ventricles of the heart.ECG interpretation - norm indicators
The transcript of the electrocardiogram is usually recorded by the doctor in the conclusion. A typical example of a normal heart ECG looks like this:1. PQ - 0.12 s.
2. QRS - 0.06 s.
3. QT - 0.31 s.
4. RR - 0.62 - 0.66 - 0.6.
5. Heart rate is 70 - 75 beats per minute.
6. sinus rhythm.
7. the electrical axis of the heart is located normally.
Normally, the rhythm should be only sinus, the heart rate of an adult is 60-90 beats per minute. The P wave is normally no more than 0.1 s, the P-Q interval is 0.12-0.2 seconds, the QRS complex is 0.06-0.1 seconds, Q-T is up to 0.4 s.
If the cardiogram is pathological, then specific syndromes and abnormalities are indicated in it (for example, partial blockade of the left leg of the Hiss bundle, myocardial ischemia, etc.). Also, the doctor can reflect specific violations and changes in the normal parameters of the teeth, intervals and segments (for example, shortening of the P wave or Q-T interval, etc.).
Deciphering the ECG in children and pregnant women
In principle, in children and pregnant women, the normal values of the electrocardiogram of the heart are the same as in healthy adults. However, there are certain physiological features. For example, the heart rate in children is higher than in adults. The normal heart rate of a child under 3 years of age is 100 - 110 beats per minute, 3-5 years - 90 - 100 beats per minute. Then gradually the heart rate decreases, and in adolescence it is compared with that of an adult - 60 - 90 beats per minute.In pregnant women, a slight deviation of the electrical axis of the heart in late gestation is possible due to compression by the growing uterus. In addition, sinus tachycardia often develops, that is, an increase in heart rate to 110-120 beats per minute, which is a functional state, and passes on its own. An increase in heart rate is associated with a large volume of circulating blood and increased workload. Due to the increased load on the heart in pregnant women, an overload of various parts of the organ can be detected. These phenomena are not a pathology - they are associated with pregnancy, and will pass on their own after childbirth.
Deciphering an electrocardiogram in a heart attack
Myocardial infarction is a sharp cessation of oxygen supply to the cells of the heart muscles, as a result of which necrosis of a tissue site that has been in a state of hypoxia develops. The reason for the violation of oxygen supply can be different - most often it is a blockage of a blood vessel, or its rupture. A heart attack captures only part of the muscle tissue of the heart, and the extent of the lesion depends on the size of the blood vessel that is clogged or ruptured. On the electrocardiogram, myocardial infarction has certain signs by which it can be diagnosed. In the process of development of myocardial infarction, four stages are distinguished, which have different manifestations on the ECG:
- acute;
- acute;
- subacute;
- cicatricial.
Sometimes it is possible to catch the phase of myocardial ischemia preceding the most acute one, which is characterized by high T waves.
Acute stage myocardial infarction lasts 2-3 weeks. During this period, a wide and high-amplitude Q wave and a negative T wave are recorded on the ECG.
Subacute stage lasts up to 3 months. A very large negative T wave with a huge amplitude is recorded on the ECG, which gradually normalizes. Sometimes the rise of the S-T segment is revealed, which should have leveled off by this period. This is an alarming symptom, as it may indicate the formation of an aneurysm of the heart.
Cicatricial stage a heart attack is the final one, since a connective tissue is formed at the damaged site, incapable of contraction. This scar is recorded on the ECG in the form of a Q wave, which will remain for life. Often the T wave is flattened, has a low amplitude, or is completely negative.
Deciphering the most common ECGs
In conclusion, doctors write the result of ECG decoding, which is often incomprehensible, since it consists of terms, syndromes, and simply a statement of pathophysiological processes. Consider the most common ECG findings that are incomprehensible to a person without a medical education. Ectopic rhythm means not sinus - which can be both a pathology and a norm. The ectopic rhythm is the norm when there is a congenital abnormal formation of the conduction system of the heart, but the person does not make any complaints and does not suffer from other cardiac pathologies. In other cases, an ectopic rhythm indicates the presence of blockades.
Change in repolarization processes on the ECG reflects a violation of the process of relaxation of the heart muscle after contraction.
Sinus rhythm is the normal heart rate of a healthy person.
Sinus or sinusoidal tachycardia means that a person has a regular and regular rhythm, but an increased heart rate - more than 90 beats per minute. In young people under 30 years of age, it is a variant of the norm.
Sinus bradycardia- This is a low number of heartbeats - less than 60 beats per minute against the background of a normal, regular rhythm.
Nonspecific ST-T wave changes mean that there are minor deviations from the norm, but their cause may be completely unrelated to the pathology of the heart. A complete examination is required. Such non-specific ST-T changes can develop with an imbalance of potassium, sodium, chloride, magnesium ions, or various endocrine disorders, often during menopause in women.
Biphasic R wave in conjunction with other signs of a heart attack indicates damage to the anterior wall of the myocardium. If no other signs of a heart attack are detected, then a biphasic R wave is not a sign of pathology.
QT prolongation may indicate hypoxia (lack of oxygen), rickets, or overexcitation of the nervous system in a child, which is a consequence of birth trauma.
Myocardial hypertrophy means that the muscular wall of the heart is thickened, and works with a huge load. This may result in:
- heart failure;
- arrhythmias.
Moderate diffuse changes in the myocardium mean that the nutrition of tissues is disturbed, dystrophy of the heart muscle has developed. This is a reparable condition: you need to see a doctor and undergo an adequate course of treatment, including the normalization of nutrition.
Deviation of the electrical axis of the heart (EOS) left or right is possible with hypertrophy of the left or right ventricle, respectively. EOS can deviate to the left in obese people, and to the right in thin people, but in this case this is a variant of the norm.
Left type ECG- EOS deviation to the left.
NBPNPG- an abbreviation for "incomplete blockade of the right leg of the bundle of His". This condition can occur in newborns, and is a variant of the norm. In rare cases, NBBBB can cause arrhythmia, but generally does not lead to the development of negative consequences. The blockade of the bundle of Hiss is quite common in people, but if there are no complaints about the heart, then this is absolutely not dangerous.
BPVLNPG- an abbreviation meaning "blockade of the anterior branch of the left leg of the bundle of His". It reflects a violation of the conduction of an electrical impulse in the heart, and leads to the development of arrhythmias.
Small R wave growth in V1-V3 may be a sign of ventricular septal infarction. To accurately determine if this is the case, another ECG study needs to be done.
CLC syndrome(Klein-Levy-Kritesko syndrome) is a congenital feature of the conduction system of the heart. May cause arrhythmias. This syndrome does not require treatment, but it is necessary to be regularly examined by a cardiologist.
Low voltage ECG often recorded with pericarditis (a large amount of connective tissue in the heart, replacing muscle). In addition, this symptom may be a reflection of exhaustion or myxedema.
Metabolic changes are a reflection of malnutrition of the heart muscle. It is necessary to be examined by a cardiologist and undergo a course of treatment.
Conduction retardation means that the nerve impulse passes through the tissues of the heart more slowly than normal. By itself, this condition does not require special treatment - it may be a congenital feature of the conduction system of the heart. Regular follow-up with a cardiologist is recommended.
Blockade 2 and 3 degrees reflects a serious violation of the conduction of the heart, which is manifested by arrhythmia. In this case, treatment is necessary.
Rotation of the heart with the right ventricle forward may be an indirect sign of the development of hypertrophy. In this case, it is necessary to find out its cause, and undergo a course of treatment, or adjust the diet and lifestyle.
The price of an electrocardiogram with a transcript
The cost of an electrocardiogram with decoding varies significantly, depending on the specific medical institution. So, in public hospitals and clinics, the minimum price for the procedure for taking an ECG and decoding it by a doctor is from 300 rubles. In this case, you will receive films with recorded curves and a doctor's conclusion on them, which he will make himself, or with the help of a computer program.If you want to get a thorough and detailed conclusion on the electrocardiogram, an explanation by the doctor of all parameters and changes, it is better to contact a private clinic that provides such services. Here the doctor will be able not only to write a conclusion by deciphering the cardiogram, but also to calmly talk to you, slowly explaining all the points of interest. However, the cost of such a cardiogram with interpretation in a private medical center ranges from 800 rubles to 3600 rubles. You should not assume that bad specialists work in an ordinary clinic or hospital - it’s just that a doctor in a state institution, as a rule, has a very large amount of work, so he simply has no time to talk with each patient in great detail.
Electrocardiography (ECG) is an instrumental diagnostic method that allows you to evaluate the work of the heart and displays the quality of electrical impulses. The result is displayed on paper. This method has been used for a long time and remains the main one in diagnosing heart diseases. Its popularity lies in the fact that it is absolutely harmless, there are no contraindications to its use, and it also takes only a few minutes to carry it out.
Everyone needs to undergo a cardiogram, regardless of whether there are complaints or not. That is, an ECG is performed during a regular preventive examination once a year, also with certain complaints and symptoms in patients.
For example, one might note:
Also, when contacting specialists, patients over 40 years of age must be sent for an ECG. It should be noted that it is important to frequently undergo this study for patients with diabetes mellitus and rheumatism, quite often an ECG is performed during pregnancy and childbirth, and the work of the heart is also examined before various surgical operations.
If a heart attack or stroke has been previously transferred, then the ECG should be done frequently to monitor the performance of the heart.
ECG indicators
The cardiogram of a healthy person consists of such elements as:
- The teeth are a convex or concave element;
- A segment is a part of a line that is located between two teeth;
- An interval is an element consisting of a tooth and a segment.
ECG interpretation
| teeth | Characteristic | Amplitude in mm | Duration | |
|---|---|---|---|---|
| seconds | millimeters | |||
| R | this tooth normally has a positive appearance. It shows excitation (depolarization) of the atria | 1,5 – 2,5 | 0,1 | 5 |
| P-Q interval (R) | This segment represents the spread of depolarization from the atria to the ventricles. | — | 0,12 – 0,20 | 6-10 |
| Q | Normally, this tooth looks like a negative one. Indicates the beginning of the process of excitation of the ventricles | — | 0,03 | 1,5 |
| R | Normally, the tooth looks positive. It is the main element of ventricular depolarization | VFI - up to 20 V 1-6 - up to 25 |
— | — |
| S | This is a negative prong. It shows the final stage of depolarization | no more than 20 | — | — |
| QRS | This is a ventricular complex, it reflects the entire process of RV and LV depolarization. | — | up to 0.12 | until 6 |
| T | This wave is positive in I, II, III, aVL, aVF and negative in aVR. It shows the process of repolarization, that is, the fading | VF1 - up to 6 V 1-6 - up to 17 |
0,16 — 0,24 | 8 – 12 |
ECG interpretation plan
There is a certain scheme by which the doctor deciphers the results of the ECG. Namely, the analysis of 4 main indicators is carried out:
Regularity and heart rate
In order to assess the regularity, that is, the correctness of the rhythm, the doctor evaluates the duration of R-R, which should be between successive cycles. Namely, in a healthy person, the duration should be the same, the difference can be within 10%. All situations that go beyond this rule are diagnosed as an abnormal or irregular heart rhythm.
With the correct rhythm, to calculate the heart rate, you need to divide the duration of the R-R interval by 60 (seconds).
If the rhythm is incorrect, then the doctor considers how many ventricular complexes have appeared in a certain amount of time. And thus calculates the frequency of the rhythm.
Source of rhythm
When analyzing the excitation source, it is estimated how the pulse propagates along the PP and LP. This is established by the appearance of the P wave. In the normal state, it is positive, rounded, located in front of the QRS. In pathological conditions, this tooth has a pointed shape, and it can also be forked.
In atrial rhythm, P may be negative (II, III), and QRS is unchanged. If the rhythms originate from the AV node, then the P wave may not appear, that is, merge with the ventricular complex. And also, if the impulse first reaches the ventricles and then to the atria, then the P wave is negative after the QRS complex. The complex is not changed.
If a ventricular rhythm is manifested, then P with QRS has no connection, while the complex is expanded and deformed.
In order to evaluate the conduction system, the doctor must calculate:
If the indicators of the duration of the teeth and intervals increase, it means that the passage of the impulse is slowed down in the lead.
Electrical axis of the heart
You can calculate the position of the EOS graphically. For this, the algebraic sum of the amplitudes of all elements of the QRS complex in leads I and III is calculated. These leads are located in the frontal plane. The resulting indicator is plotted on the corresponding axis (positive or negative) and in the corresponding assignment on the conditional coordinate system.
Electrical axis of the heart
You can also use another method. This determines the angle. These measurements are carried out according to 2 principles. The first is that the maximum value of the algebraic sum of the QRS complex is recorded in the lead, which corresponds to the location of the EOS. The mean value is plotted in the same lead. The second principle is that RS with zero algebraic sum is recorded in a lead that is perpendicular to the EOS.
Determination of the rotation of the heart around the longitudinal axis, which conditionally passes through the upper part of the heart and its base, consists in determining the configuration of the ventricular complex in the chest leads. This is because these axes are horizontal. The QRS complex in lead V6 is assessed to determine rotation.
Conduction disorder
Conduction disorders are blockades that can manifest themselves at different stages of the conduction system. This violation can manifest itself in 3 degrees. 1 - this is when the impulses pass, but with a delay. 2 - at this stage, only a part of the impulses is carried out. 3 - this is a complete blockade, while the impulse does not pass at all.
On the electrocardiogram, grade 1 rarely manifests itself.
heart block
With sinoauricular blockade of the 2nd degree, after a contraction, a pause may occur, which takes 2 cycles in duration. That is, the full PQRST complex falls out.
Atrioventricular block. At grade 1, PQ slows down, the duration of this interval can increase up to 0.2 seconds. And the ventricular QRS complex does not change at the same time, it can be deformed if the conductivity slows down in all the legs of the His at the same time.
In grade 2 AV block, the P wave appears regularly, but there is no QRS complex behind it (the PQ interval is also absent). The ventricular complex appears with regularity once, after 2-3 P waves. This means that the number of atrial contractions is much greater than the ventricular contractions.
Heart block on EKG
3 degree AV blockade on the ECG looks like a separation of the P wave and the QRS complex, that is, there is no PQ interval.
If the proximal form is manifested, then the QRS is not changed, and in the distal form, its expansion and deformation appear.
reading teeth
Prong P - this element indicates the depolarization of PP and LP. Normally R is positive.
The Q wave reflects depolarization of the interventricular septum. This element is negative. Its normal size is considered to be ¼ of the R wave, its duration is 0.3 seconds. If it is increased, then this may indicate diseases of the myocardium.
R wave - this element shows the depolarization of the apex of the heart. Reading this wave provides information about the activity of the ventricular walls. The R wave should be the same in all leads, if this is not the case, then this may mean the presence of RV or LV hypertrophy.
The S wave is negative. Its size is about 2 mm. The S wave shows the final process of RV and LV depolarization.
The T wave reflects the repolarization of the ventricles, that is, the process of their extinction. It has a positive appearance, but in the VR lead it is negative. If this tooth is changed, then this may indicate the presence of hyperkalemia or hypokalemia.
The PQ interval is an element that consists of the end of P and the beginning of Q. It shows the complete process of atrial depolarization and the propagation of the impulse to the AV node and along the bundle of His. PQ duration is 0.12-0.18 seconds.
The QT interval is estimated by calculating it according to the formula, that is, a fixed coefficient is multiplied by the duration of the R-R interval. For men, the coefficient becomes 0.37, and for women - 0.40.
ECG norm in adults
It should be noted that during an ECG, the heart rate becomes 60-90 beats per minute. The duration of the R-R intervals is the same, the deviation can be within 10%. Norms for adults:
Loading...