Sudden cardiac death is usually caused by ventricular fibrillation. This means the heart does not simply stop but instead beats suddenly at a frequency of over 300 beats per minute. However, ventricular fibrillation also occurs during cardiac arrest because the pump function no longer works at this high rate.
Sudden cardiac death is characterised by sudden collapse. Ventricular fibrillation is almost always the cause. The heart suddenly beats at a frequency of over 300 beats per minute, which causes the pump function of the heart to come to a halt. All of a sudden, the body is no longer supplied with oxygen. The brain reacts to this by causing the patient to lose consciousness within seconds.
Only quick action and immediate first aid can save their life in such a situation. Ventricular fibrillation must be stopped as quickly as possible with a defibrillator. If there is a defibrillator nearby, laypeople should also use it. It is easy to handle and each defibrillator comes with a set of illustrated instructions for use. If there is no defibrillator nearby, first aid must be given in the form of heart massage, along with ventilation, if need be, until the ambulance arrives. Recent studies have shown that heart massage is much more important than ventilation. Therefore, the new regulations recommend that you perform heart massage instead of ventilation if you provide first aid on your own. Heart massage should also not be performed with overly long pauses in between; the chest must be pressed inwards by 5–6 cm with both hands on the breast bone at a frequency of 100 to 120 times per minute. Do not worry that you are going to injure the patient in the process. Heart massage causes blood to be pumped through the body, and this is crucial for the patient's survival. Any possible injuries caused by heart massage are of no consequence. You should carry out heart massage until medical help arrives.
If the patient is successfully resuscitated, the reason for the ventricular fibrillation will then be sought and treated. The actual cause of ventricular fibrillation is usually coronary heart disease with a circulatory disorder. Wearable defibrillators which recognise the beginning of ventricular fibrillation and start defibrillation to prevent further ventricular fibrillation can be implanted. Find out more in the chapter entitled Surgery for cardiac arrhythmia.