Introduction
The ECG is a procedure that can be used to record electrical signals from the heart. It is a very simple and inexpensive examination method, so it is available almost everywhere. In principle, the ECG can provide initial indications of heart disease, but it is not particularly specific for the diagnosis of myocardial inflammation. This is mainly because myocarditis itself can take on very different clinical manifestations. Therefore, the ECG is very valuable as the first diagnostic tool, but depending on the findings, other procedures such as imaging (X-ray, ultrasound or MRI) may need to be consulted.
What ECG changes does a myocardial infarction cause?
The ECG changes caused by myocarditis are very diverse and present themselves as differently as the clinical symptoms of the disease. Since the ECG records the electrical currents in the heart, cardiac arrhythmia in particular can be detected. These disturbances range from a heartbeat that is too fast (tachycardia) to additional heartbeats (extrasystoles) to a severe arrhythmia in which the heart can no longer produce efficient beats.
Because the electrical currents of the heart are conducted at different locations, disturbances in the excitation conduction can be localized well. In addition, it is possible to estimate the size of the affected area and thus the severity of the disease. In myocarditis, a phenomenon similar to a heart attack can occur.
It is called ST-segment elevation. In the recorded ECG, the distance between the S-wave and the T-wave is elevated and is no longer at the zero line. However, an ST segment depression or T-wave negation, in which the normally positive T-wave points in the opposite direction, is just as possible.
In addition, severe disturbances of the excitation conduction affecting an entire heart chamber can be diagnosed. Such a disturbance is called a thigh block. A heartbeat consists of the tension phase (systole) and the relaxation phase (diastole).
In diastole, the heart chambers fill with blood, which is pumped into the circulation in systole by the tensing of the heart muscles. Extrasystoles are additional beats of the heart. They are sometimes also called cardiac stumbling.
They usually occur as a result of a disturbed excitation conduction. This disturbance can be triggered by an inflammation of the heart muscle, for example. A distinction is made between ventricular extrasystole, where the conduction disorder is located in the ventricles, and supraventricular extrasystole, where the conduction disorder is located in the atria.
Tachycardia is the technical term for a too fast heartbeat. This can, for example, be the result of inflammation of the heart muscle. The inflammation causes the excitation conduction system of the heart to be disrupted.
The electrical impulses that generate a normal heartbeat are transmitted incorrectly and send signals to the heart muscle cells in the atria or ventricles that are too fast. These contract and pass on the too fast signal to the next cells. This can throw the entire heart rhythm out of balance.
Between the atria and the ventricles is the so-called AV node. This node conducts the electrical excitation from the atria into the ventricles, where it causes the muscle cells to contract. This conduction can be disturbed by myocarditis.
In this case, the AV node blocks the transmission of electrical currents and the heart twitches irregularly. This is called an AV block. In most cases, the atria and ventricles beat independently of each other and no longer evenly.
If this electrical conduction disturbance occurs a little further down, a thigh block can occur. The left thigh of the heart is often affected, so that this is referred to as a left thigh block. A left bundle branch block therefore means that no electrical signals are transmitted to the left ventricle. As a result, they do not move and no blood is pumped into the circulation. This part of the heart therefore stands still.
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