Electrocardiography (ECG) is one of the electrophysiological methods of registration of biopotentials of the heart. Electrical impulses in cardiac tissue are transmitted to the cutaneous electrodes placed on the arms, legs and chest. This data is then displayed either graphically on paper or displayed.
The content of the article
In the classic version, depending on the location of the electrode is isolated, so-called, standard, reinforced and chest leads. Each of them shows bioelectric impulses taken from the heart muscle from a certain angle. Through this approach, eventually emerges in the electrocardiogram, a complete characterization of each portion of the heart tissue.
Figure 1. ECG strip image data
What does an ECG of the heart? With this common diagnostic method to determine the specific location in which the pathological process. In addition to any disorders in the myocardium (heart muscle), ECG shows the spatial location of the heart in the chest.
The main problem of electrocardiography
- Timely identification of violations of rhythm and heart rate (detection of arrhythmias and extrasystoles).
- Definition of acute (myocardial infarction) or chronic (ischemia) organic changes of the heart muscle.
- Detection of violations of intracardiac nerve impulses (conduction of electrical impulse in conducting system of the heart (blockade)).
- Determination of some acute (pulmonary embolism – pulmonary embolism) and chronic (chronic bronchitis with respiratory failure) pulmonary diseases.
- Identification of electrolyte (potassium, calcium) and other myocardial changes (degeneration, hypertrophy (increase in thickness of the heart muscle)).
- Indirect registration of inflammatory heart disease (myocarditis).
The disadvantages of the method
The main disadvantage of electrocardiography is a short-term registration parameters. I.e. recording shows the heart only at the time of ECG at rest. Due to the fact that the above disorders can be transient (appear and disappear at any time), professionals often resort to daily monitoring and recording ECG with load (load tests).
Indications for ECG
Electrocardiography is performed on a regular or emergency basis. Routine ECG is recorded during the management of pregnancy, when a patient in the hospital, in the process of preparing a person for surgery or complicated medical procedures, for evaluation of cardiac activity after a specific treatment or immediate medical intervention.
Prophylactic ECG is assigned:
- people with high blood pressure;
- for atherosclerosis;
- in the case of obesity;
- if giperholesterinemia (increased levels of cholesterol in the blood);
- after some infectious diseases (sore throat, etc.);
- in diseases of the endocrine and nervous systems;
- persons over the age of 40 and people who are prone to stress;
- rheumatologic diseases;
- people with occupational risks and hazards for evaluation of competency (pilots, sailors, athletes, drivers…).
In case of emergency, i.e. “in the moment” ECG is assigned:
- pain or discomfort behind the breastbone or in the ribcage;
- in case of sudden shortness of breath;
- prolonged severe pain in the abdomen (especially in the upper parts);
- in case of persistent high blood pressure;
- if you experience unexplained weakness;
- loss of consciousness;
- in trauma of the chest (in order to avoid heart damage);
- at the time of or after the cardiac arrhythmia;
- for pain in the thoracic spine and the back (especially the left);
- when severe pain in the neck and lower jaw.
Contraindications to ECG
Absolute contraindications to ECG no. Relative contraindications to electrocardiography can be various violations of the integrity of the skin in areas of attachment of the electrodes. Remember, however, that in the event of an emergency, paramedics ECG must be removed without exception.
Preparation for electrocardiography
Special preparation for the ECG also does not exist, but there are some nuances of the procedure, which patient should notify physician.
- It is necessary to know whether the patient takes heart medications (should be marked on the form of direction).
- During the procedure, it is impossible to speak and move, you need to lie down, relax and breathe calmly.
- To listen to and follow simple commands of the medical staff, if necessary (to breathe in and not breathe for several seconds).
- It is important to know that the procedure is painless and safe.
Distortion of the electrocardiogram recording is possible with the movements of the patient or in case of improper earthing of the machine. Cause the wrong entries are also can be a loose fit of the electrodes to the skin or improper connection. Noise in the recording often when muscular tremor or in case of electrical fire.
Conducting ECG or EKG how do
Figure 2. The imposition of the ECG electrodes When recording the ECG, the patient lies on his back on a horizontal surface, arms stretched along the body, legs straight and not bent at the knees, Breasts exposed. Ankles and wrists are attached to one electrode according to the generally accepted scheme:
- to the right hand red electrode;
- to the left hand – yellow;
- to the left leg.
- to the right leg – black.
Then the chest is overlaid with 6 electrodes.
After full connection of the patient to the ECG device is of record that in modern electrocardiographs lasts no more than one minute. In some cases, the health care provider asks the patient to inhale and hold your breath for 10-15 seconds and holds at this time of additional recording.
At the end of the procedure, ECG tape, you specify the age, name of patient and the rate at which removed cardiogram. Then the specialist is a transcript.
Transcript of ECG and interpretation
Transcript of the electrocardiogram is conducted by a cardiologist or a doctor of functional diagnostics, or paramedic (in terms of the ambulance). The data is compared with a reference ECG. ECG usually there are five main teeth (P, Q, R, S, T) and the subtle U-wave.
ECG decoding in adults, the rate in the table
Various changes of teeth (their width) and spacing may indicate a slowing of conduction of nerve impulses in the heart. The inversion of tooth T and/or the rise or decline of the ST interval relative to isometric line indicates possible damage to the myocardial cells.
During the decoding of ECG, in addition to learning shapes and spacing of all teeth, conduct a comprehensive assessment of the entire electrocardiogram. In this case, we study the amplitude and direction of all waves in standard and reinforced leads. These include I, II, III, avR, avL and avF. (see Fig.1) Having the total picture of these elements of the ECG can be judged on the EOS (electrical axis of the heart), which indicates the presence of blockages and helps to determine the location of the heart in the chest.
For example, in obese individuals, EOS may be rejected left and down. Thus, the ECG interpretation contains all the information about the source of the heart rate, conductivity, size of cardiac chambers (Atria and ventricles), changes of the myocardium and electrolyte disorders in the cardiac muscle.
The main and most important clinical significance of ECG is myocardial infarction, violations conductivity heart. Analyzing the electrocardiogram, it is possible to obtain information about the focus of necrosis (localized myocardial infarction) and its limitations. It should be remembered that the evaluation of the ECG should be performed in conjunction with echocardiography, daily (Holter) ECG monitoring and functional load tests. In some cases, the ECG can be almost uninformative. This occurs when massive intraventricular blockades. For example, PBLNK (full blockade of the left leg of the beam gissa). In this case, it is necessary to resort to other diagnostic methods.