What is it?
A long-term ECG is the permanent recording of an electrocardiogram, usually lasting 24 hours. An ECG measures electrical potentials via electrodes that are attached to the skin at various points on the body. The measurements through the electrodes lead to a cassette-like recorder which is hung around the neck with a tape.
The measurement is performed permanently without the patient noticing anything. In contrast to long-term blood pressure, no cuff is inflated and the measurement is not noticeable. This means that even sleep at night is not disturbed by the recorder or the electrodes.
During the 24 hours, the patient keeps a log of which activities were performed at a certain time. On the basis of this, the doctor can assess which everyday situation has an influence on the heart activity. The measurement usually starts early in the morning in the cardiological practice.
About 24 hours later, the device is delivered to the practice. After that it takes a few days to weeks until the doctor has evaluated the results and made a diagnosis. On this basis, further examinations or therapies can be discussed.
Every single heartbeat through the heart muscle cells is triggered by electrical impulses. For this purpose, the heart has an excitation conduction system consisting of numerous nerve cells that runs from the left atrium through the entire heart. Due to its own excitation system, the heart works independently and does not need a permanent drive from the brain.
It can only be influenced in force, speed and excitability. Between excited and unexcited areas of the heart there are electrical voltage changes that can be measured on the skin surface. Therefore, at least two electrodes are needed to measure the signals.
Depending on the change in voltage, it is possible to trace how the electrical excitation spreads in the heart. By using up to six electrodes, the position and propagation of the excitation can be assessed more accurately. In contrast to clinical routine, long-term ECG recordings are made over 24 hours in order to be able to examine the excitation of the heart in different phases of everyday life outside the practice.