An electrocardiogram (ECG, EKG) is a graphic record used to identify the changes in the way and magnitude of the electrical impulses created by the depolarization wave. Impulses pass through the ventricles and the atria. The ECG was invented by Willem Einhoven in 1901. Since then, it has become one of the least expensive and most effective methods in cardiac diagnostics.
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The ECG gives many opportunities in analyzing the heart’s state, its failures, and further treatment measures. The procedure is used for the following purposes: defining the frequency of the heartbeat; identifying the existence of extrasystoles; identifying the myocardium infarction and ischemia; discovering breaches in the metabolism of calcium, magnum, potassium, and other electrolytes; finding out breaches in the heart’s inner conductivity; screening in case of ischemia; revealing the hypertrophy of the left ventricle; obtaining information about such diseases as pulmonary embolism; diagnosing the acute heart pathologies with the help of the card iPhone. The ECG is also necessarily used in the procedure of medical screening.
This variety of functions leads to the conclusion that the ECG may be used both in a hospital by qualified specialists and by paramedics in case of emergency. The procedure plays a significant role in getting data about the illness and the heart’s state in general. It allows paramedics to give urgent help to the patient suffering from a heart attack or another cardiac disease. One of the advantages of the method is that it gives precise data.
One of the most important terms for understanding how the ECG works is the voltage gradient. It shows the difference between positive and negative charges. The electrical current takes the form of waves which demonstrate the depolarization and repolarization of the heart. This information is placed on the record and represented from various perspectives called leads (or planes).
In the case of the surface ECG, the leader demonstrates the characteristics of the heart’s activity between two poles – a negative one and a positive one. Depending on which pole the current flows to, the deflection may be either negative or positive, respectively. To detect electrical activity, electrodes are used. According to the information coming from them, the display shows positive electrical impulses as upward waves and negative ones as downward waves.
Standardly, in the ECG, three bipolar limb leads are used. This model is called the three-lead ECG. The first lead works positively on the left arm and negatively on the right one. The second and third leads are attached both to legs and arms: the second one is positive on the left leg and negative on the right arm, while the third is positive on the left leg and negative on the left arm.
Analyzing electric impulses, the ECG identifies any existing abnormalities. If the P-wave’s depolarization is changed, it may be due to the increased pressure in an atrium. It may also be an indicator of valve disease, deficiencies in conduction, or the ectopic pacemaker. In these cases, the P-wave looks peaked, notched, or prime (P’).
It is necessary to consider QRS abnormalities as they occur frequently. In this case, the wave looks upright, inverted, or notched. It is also possible that the wave’s duration is more than 0.12 seconds. All these things may happen due to the following reasons: the intraventricular conduction is disturbed; the ventricular conduction is abnormal; the ventricular is pre-excited; a ventricular ectopic pacemaker is observed; the ventricular pacing is viewed.
T-waves are significant to consider as well. In their normal state, they are in an upright position, lasting from 0.10 to 0.25 seconds, with an amplitude of 5 mm. They are characterized by ventricular repolarization. In this case, an isoelectric line is observed above or below while the wave looks rounded and lacks symmetry. If a T-wave is peaked or inverted, it may occur because of AMI/ACS, BBB, an imbalance of electrolytes, or hyperventilation.
It is necessary to provide examples of various heart diseases which are quickly and easily identified by the ECG. One group of common abnormalities exposed by the method is sinus node ones. Firstly, it is sinus tachycardia. In this case, the hiring rate exceeds 100 per minute. It may be even higher with children and babies. The disease may be caused by different reasons such as pain, virus infection, hypotension, hypoxia, use of medicaments, and stress. Secondly, the contrary to this disease is sinus bradycardia, in which the hiring rate is less than 60 per minute. It is more observed among children than among grown-ups. It may be caused by medication effects, hypothermia, high vagal tone, or hypothyroidism. This problem is typical of athletes who take special drugs. Thirdly, sinus arrhythmia is a widely-viewed problem. Usually, young people with no serious health deficiencies and with good baroreceptors suffer from it. In most cases, the disease is related to defective respiration. If it occurs among seniors, it is frequently caused by dioxin effects or IHD. However, this is not a dangerous disease, and it has no clinical significance.
Various atrial problems are also identified by the ECG. For example, multifocal atrial tachycardia implies a rate higher than 100 beats in one minute. It may be caused either by hypoxia or COPD. Usually, it is not a problematic phenomenon, but if it causes discomfort, it requires ventricular rate control combined with medical treatment. Another example of atrial problems is flutter. It is a more serious issue that may be caused by enlarged atrial tissue, high atrial pressures, valve illness, hyperthyroidism, pericardial illness, or cardiac surgery. One more instance is atrial fibrillation. It implies that a large number of chaotic impulses are observed. In this case, no P-waves or a lot of them are viewed. Atrial contraction is not seen. This heart disease is frequently caused by hypertension, valvular illness, coronary artery disease, and COPD. However, it may also be a consequence of any other heart problem. To get rid of it, rhythm control and reversion are used.
The mentioned examples show that the ECG may identify both serious heart diseases and minor cardiac problems. The equipment presupposed by this method thoroughly analyzes electric impulses created in the heart. The information obtained from the cardiogram is used to diagnose the illness and give the patient first medical aid. That is why the method is widely used both in hospitals and in emergency cars.