Between 800 and 1000 people die in Gipuzkoa each year as a result of sudden death. These deaths are thus certified because the fatal outcome is unexpected. It affects apparently healthy persons or ill people but who lead normal lives. In many cases the outcome itself is the first sign of the illness. Most cases have a cardiovascular origin. The cardiac rhythm undergoes a change known as ventricular fibrillation. This involves a very rapid arrhythmia - more than 400 beats a minute. The heart cannot pump blood and it stops. Given a case of sudden death, it is vital to administer treatment immediately. If it is not administered within ten minutes, death is certain. On the other hand, if the treatment takes place within two minutes, there is a 100% survival rate. An electrical discharge with a defibrillator makes the difference between life and death. This is why, in order to avoid avoidable deaths, there is an increasing number of public locations where automatic, user-friendly defibrillators are installed. Although in half of the cases the symptoms manifest themselves unexpectedly, there are persons who have a higher risk of dying suddenly. These are patients with cardiac complaints or who have already had a heart attack. Their risk can be quantified. In some cases, to avoid the crisis and thereby, death, an IAD is implanted. Policlínica Guipúzcoa and the Hospital Donostia are two of the centres where implants are carried out. These devices consist of a number of wires connected to the heart and to a central unit located under the skin; the programming is personalised and stores in its memory all the arrhythmias and electrical discharges undergone by the patient. About 70 defibrillators of this type are implanted every year in Gipuzkoa - with excellent results. The IAD controls the patient’s heart and is automatically activated in a crisis. The defibrillator comes into action within 8 seconds. The patient recovers the heartbeat without even realising that a crisis has taken place, although they will feel a small electrical discharge. After 4 years of IAD implants, 80% of the patients have suffered a crisis. The IAD does not interfere with their daily lives but, above all, they stay alive. The number of persons who have been saved from certain death is the same as the number of devices implanted. In the last few years a new type defibrillator has been tested – it is similar but with the difference that it is placed onto the skin of the patient. It is suitable for situations of transitory risk and enables its fitting and its removal without any surgery.