Among the examinations that are often performed as part of a hypertension diagnosis is the ECG.
ECG stands for Electrocardiogram. The term indicates that it has something to do with electricity and the heart (cardio). It is an examination of the heart. The history of the ECG dates back to 1882 when physiologist Waller succeeded in deriving the first ECG. Around 1900, the method was further developed and refined for clinical application. In 1924, the Dutchman Willem Einthoven received the Nobel Prize for his groundbreaking advancements in the method. He is considered the inventor of the ECG.
How is the ECG performed?
For the ECG examination, the upper body must be undressed, and the forearms and lower legs must be accessible, as the ECG electrodes are either glued on or attached to the skin using light suction. Both methods are completely painless. In cases of pronounced body hair, the necessary areas are shaved to ensure the electrodes adhere properly.
What types of ECG are there?
In the doctor's office, three different types of ECG are usually used: the resting ECG, the stress ECG, and possibly the long-term ECG. Additionally, there are several other types that are primarily used in hospitals or emergency services. We explain the most common variants used in the doctor's office.
Resting ECG
A resting ECG is performed while lying down and takes only a short time. The patient lies relaxed on the examination table, and the electrodes are attached. After a short waiting period to allow the patient to calm down, the ECG is recorded.
Stress ECG
The stress ECG records the heart's activity under stress and the subsequent phase until the resting state is reached again. The patient usually sits on a bicycle ergometer (stationary bike), is also equipped with ECG electrodes, and then begins to cycle. The load increases at set intervals until the individual stress limit is reached - after which the resting phase follows. Throughout this time, the ECG is recorded to observe the heart's activity under stress as well as during the following resting phase.
Long-term ECG
The long-term ECG is a small box connected to the electrodes via cables. These are attached to the patient's upper body. The patient then wears the device continuously until the next day. During this time, the ECG is recorded. This allows the doctor to see how the heart has functioned during the wearing period.
What is recorded during an ECG?
Just before each heartbeat, an electrical excitation forms in our heart, spreading like a wave through the various regions of the heart, causing the heart muscle fibers to contract. This is referred to as conduction of excitation.
These weak currents can be measured using electrodes on the skin and made visible as lines, waves, and spikes - the so-called ECG curve - through the ECG device. The ECG curve thus represents the course of excitation in the heart.
Through the commonly used 12-lead ECG in most practices, where a total of twelve electrodes are placed on the upper body and on the arms and legs, twelve different leads can be recorded, which have high diagnostic value.
What does the doctor see on an ECG?
First of all, the heart rhythm is visible - the more or less regular sequence of spikes. This also indicates how fast the heart is beating. The shapes and sequences of the lines, waves, and spikes reveal even more to the doctor about the heart. He can observe the formation, spread, and recovery of excitation. From this, he can draw conclusions about the atria and ventricles of the heart (whether the heart is enlarged, whether there is an acute or older heart attack, and so on), in addition to the rhythm and heart rate.
This makes the ECG an important and highly informative examination method that can guide the way to further procedures.
ECG devices for home use and smartwatches
Various very handy ECG devices are available that are suitable for use by the patient themselves. These devices record the heart rhythm over a short period - usually about 30 seconds - and provide immediate feedback on whether deviations are present. Most of the devices work with a single lead, for which no electrodes need to be attached. The device is held between the hands, against the chest, on the wrist, or on the ankle to record the heart rhythm. The data is then transferred to an app or software, allowing it to be documented and possibly presented to the doctor. The diagnostic value of these 1-lead ECGs is limited - they are primarily suitable for detecting heart rhythm disorders (arrhythmias).
Other devices offer the possibility to derive a 3-lead ECG using a supplied cable and electrodes. This provides more interpretative options, but the potential for errors due to incorrect electrode placement is also greater. The interpretation of the recorded ECG is the responsibility of the doctor, as appropriate training and experience are necessary for this.
Various smartwatches also offer the ability to record an ECG. This is a simple 1-lead ECG that can provide information about certain rhythm disorders. This function can be particularly helpful for detecting atrial fibrillation, which often occurs sporadically.
Sources:
- https://www.netdoktor.de/diagnostik/ekg/
- http://flexikon.doccheck.com/de/Elektrokardiogramm
- http://flexikon.doccheck.com/de/Einkanal-EKG
- https://www.aerzteblatt.de/archiv/134914/Mobiles-EKG-Geraet
- https://www.apotheken-umschau.de/e-health/ekg-mit-smartwatch-wie-zuverlaessig-sind-die-messungen-1111157.html
By Sabine Croci. This article is medically reviewed. Last updated (11/2024).
Information on the website and within the app cannot replace a consultation with a doctor, but can certainly complement it.
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