An ECG is a very common and important examination method that can be used to record the electrical activity of the heart muscle cells. "Electro" describes the electrical excitation, "cardio" refers to the heart and "gram" means writing. This is why the ECG is also referred to as cardiac writing.
Every heartbeat is controlled by electrical excitation, which originates from the so-called sinus node (pacemaker) and spreads throughout the entire heart and all heart muscle cells. The heart can only beat well and powerfully if this excitation is regular and coordinated.
The ECG as the so-called "cardiac transcript" can reveal excitation disorders and thus damage to the heart muscles and cardiac arrhythmia. This is very important in the event of a heart attack, for example, and can be life-saving.
The ECG is particularly important for specialists who specialize in heart disease. These include cardiologists and cardiac surgeons in particular. However, due to its ease of use and the fact that it can be performed anywhere, the ECG is used very frequently in all specialties, both in hospitals and in medical practices. Reading an ECG and recognizing important findings is part of medical training. Rare and complex findings, however, fall under the specialty of cardiology.
Even though it involves measuring electrical activity, an ECG is a completely painless examination with no side effects. No electric shocks are administered, as you might think on first reading. During the ECG, measuring electrodes are applied to the chest and extremities from the outside. These are either glued in place or fixed with special suction electrodes.
This test method is simple and can be carried out anywhere. It is supplemented by measuring the pulse and blood pressure, but is much more specific and accurate with regard to clarifying cardiac rhythm and conduction disorders.
An ECG is usually first used to rule out heart disease. This is why it is used, for example, for preventive examinations. An ECG is also often performed before major operations in order to detect previously undetected and asymptomatic heart problems. However, it is much more common for an ECG to be unremarkable so that serious heart disease can be ruled out. Further examinations are then no longer necessary in such cases and the anesthetist has no objections to the operation. Patients can thus be spared a cardiac catheterization.
However, if there are abnormalities in the ECG, further examinations are necessary for more precise clarification and complete decoding of the clinical picture. In addition to the cardiac catheterization, this also includes a cardiac ultrasound examination and sometimes an MRI scan of the heart muscles and coronary vessels(cardiac MRI).
There are different types of ECGs that are based on the same principle. A resting ECG is performed once on a patient who is in a normal physical state. The rhythm, frequency and intensity of the pumping function are not affected by external influences, especially physical exertion.
The exercise ECG is used while the patient is physically exerting themselves. The performance is compared with ergometric specifications in order to reveal deviations from the norm.
In order to obtain more meaningful results and to listen to the body in a situation-specific manner, a long-term ECG is used. The patient usually wears a device on their body for 24 hours, which measures their heart rate around the clock. The electrodes of the ECG device are attached and the device is placed in a small bag that the patient can wear. A long-term ECG is usually performed in hospital, but can also be carried out on an outpatient basis at home. The subsequent evaluation is carried out by a heart disease specialist.
Resting ECGs are used when an anamnesis (discussion of the patient's medical history) and general physical examination, especially blood pressure and pulse, give rise to the suspicion of heart disease.
For example
- a pulse that is too fast or irregular and
- blood pressure abnormalities (both upwards and downwards) should always be regarded as suspicious. But even with already
- known heart diseases
- to check the condition after a heart attack or
- an ECG is routinely performed before major surgical procedures.
The ECG is then part of the further routine examinations which should reveal the cause of any malfunctions in the functioning of the cardiovascular system.
A resting ECG is performed to get an initial impression of how well the heart is functioning. In most cases, the resting ECG is suitable for ruling out serious heart disease. If the patient has an unremarkable medical history and denies heart pain at rest and during exercise, an unremarkable resting ECG is sufficient and further examinations are not necessary.
The ECG can provide indications of a variety of diseases, some important examples are listed below:
The clinical pictures listed can be detected by an ECG before the patient expresses any major complaints. It can also monitor the condition and success of a therapy measure after the treatment of a disease, for example heart valve surgery, and provide early indications if problems occur again.
An exercise ECG is ordered when
This allows constrictions in the stents or in the bypass to be detected at an early stage by changes in the ECG during exercise. However, it is important that the exercise is moderate so as not to trigger a cardiac complication during exercise. In the first weeks and sometimes months after a heart bypass operation, physical exertion and exercise ECGs are contraindicated, which means that they should not be performed.
Anyone planning a major sporting competition should also have an exercise ECG performed. A sports medical check-up is recommended, for example, for all athletes who are planning to run a marathon or regularly take part in one. In addition to a detailed physical examination and a blood test, the sports medical check-up also includes an exercise ECG. If the findings are normal, a certificate of fitness for sport is issued. For some competitions, this sports medical certificate is a prerequisite for being allowed to take part in such a sporting event.
In most cases, the ECG is not an indicator of the severity of a heart condition. It merely shows that there is a disturbance in the excitation of heart muscle cells. The ECG can be used to make a suspected diagnosis, so to speak, which can be confirmed by further examinations such as ultrasound or an MRI scan.
The gold standard for confirming the diagnosis of coronary heart disease, which is understood to mean narrowing of the coronary arteries as the cause of a heart attack, is coronary angiography. However, this is an invasive examination that requires a catheter to be inserted into the body. The ECG is non-invasive, which means that the integrity of the body is guaranteed.
In order to be able to make more precise statements about heart disease in the case of abnormal ECGs, further examinations are necessary. These include above all the cardiac ultrasound examination ("cardiac echo"), which has no risks or side effects and can be repeated as often as required. The cardiac ultrasound examination can be used, for example, to assess the heart valves, the heart cavities and the blood flow.
To summarize, the ECG is a non-invasive, painless method for checking the performance of the heart. Its precise information on the health of the heart is comprehensive and can be analyzed by all medical professionals, especially cardiologists, to produce detailed findings. It is one of the most important examinations in medicine and has become an indispensable part of everyday clinical practice