What’s asystole?

The term asystole is a medical term. It describes the complete absence of electrical and mechanical action of the heart, i.e. the heart stops. Asystole is fatal within minutes if left untreated and requires immediate medical intervention. An asystole can be detected in the ECG. Clinically it is indicated by a missing pulse.

Causes of asystole

In most cases it is not a primary asystole. In most cases, the asystole is preceded by ventricular fibrillation. Ventricular fibrillation is a cardiac dysrhythmia in which the heart no longer pumps in a coordinated manner due to a disturbance in the excitation conduction, but only fibrillates very rapidly.

The actual function of the heart to pump blood through the body is no longer given. Possible causes for such a ventricular fibrillation are heart diseases such as coronary heart disease, valvular defects and cardiomyopathies. However, other diseases such as electrolyte disorders (especially potassium) or certain medications and drugs can also trigger ventricular fibrillation.

It is therefore not possible to name the causes of asystole. This has to do with the fact that every dying patient has an asystole at the time of death. So the asystole is always and in every dying person in the last phase of the ECG.


Asystole is a diagnosis that is made on the basis of the ECG. It is indicated here by a zero line. This is caused by the absence of any electrical or mechanical activity of the heart.

Asystole is clinically indicated by a missing heartbeat and therefore a missing pulse. The pulse can be felt on the wrist, groin, neck and numerous other regions. However, in the current resuscitation guideline, palpation of the pulse in a resuscitation situation is not recommended because it may take longer to find the pulse in some patients and because palpation of the pulse in the acute situation is not sufficiently reliable.

Asystole is shown in the ECG by a so-called zero line. This means that there is a horizontal line in the ECG, where normally jagged lines and curves can be seen. There is no impending asystole. However, many patients suffer from ventricular fibrillation before asystole. This is shown by uncoordinated, fast, irregular flicker waves in the ECG.

Associated symptoms

In the case of asystole, the affected person is unconscious. Breathing has stopped and no pulse can be felt because the heart is no longer beating. Unconsciousness occurs after a few seconds of asystole. The patient may still feel dizzy-like symptoms at the moment of the onset of asystole. A syncope then occurs, i.e. a fall due to sudden unconsciousness.

Treatment and resuscitation

The only effective treatment for asystole is the attempt of resuscitation. Especially if a patient is currently undergoing inpatient treatment, is older and has other serious underlying diseases, the possibility of such a situation occurring should always be discussed with the patient and relatives at the beginning. The wishes of relatives and patients must be considered.

Not all patients want resuscitation. If a patient speaks out against resuscitation in advance, it is not allowed to carry out resuscitation – in case of the worst case scenario. The procedure for resuscitation differs depending on whether the patient is in ventricular fibrillation or asystole.

Before starting resuscitation, it must be checked whether the patient is responsive or breathing, in which case resuscitation is not necessary. In layman’s resuscitation, it is essential that a call for help is made via 112 before resuscitation begins. Ideally, there should be several people on site so that one person can start the resuscitation while the other makes the emergency call.

In resuscitation, a distinction is made between cardiac massage with ventilation and defibrillation. Cardiac massage is performed 30 times at a rate of about 100/min, then two breaths are given. Cardiac pressure massage is more important than ventilation, which can be omitted by laypersons.

Defibrillation is performed with an appropriate device (AED = automatic external defibrillator for laypersons or specialist equipment). However, defibrillation, i.e. shock delivery, only takes place if the applied ECG shows ventricular fibrillation, not in case of asystole. In the case of asystole, resuscitation consists of cardiac massage and ventilation cycles of 30:2 each.

Rhythm control is performed at regular intervals via the ECG. If the patient is still asystole, this type of resuscitation is continued. If the asystole changes to ventricular fibrillation, defibrillation is performed.

If the normal rhythm returns, the patient should be palpated after a pulse is present and the patient should be addressed. In general, when resuscitation is carried out by qualified personnel, a venous access is made immediately, but resuscitation must not be significantly delayed by this. In case of asystole, adrenaline is injected immediately.

This is repeated every 3-5 minutes. In the event of resuscitation by specialist personnel, the airways are also secured. There are various possibilities for this, intubation is still the gold standard, but nowadays it is no longer necessary as there are other possibilities for an adequate airway protection (Laryngeal Tube, Combitubus, Laryngeal Mask). Resuscitation is successful if the circulation is restored.