Sudden cardiac arrest is one of the most common causes of death in the United States . Around 450,000 Americans suffer from cardiac arrest each year and around 80 per cent of people die before they reach the hospital.

 

In most of these cases, the conditions that caused the cardiac arrests could be treated or monitored by defibrillators.  There are two basic types of defibrillators- external and implantable.

 

Implantable defibrillators are small electronic devices installed inside the chest to prevent sudden death from cardiac arrest due to life threatening conditions such as abnormally fast heart rhythm or tachycardia.

 

When the heart is beating normally, the defibrillator remains inactive. If the heart develops a life-threatening tachycardia, the defibrillator delivers an electrical shock to the heart to terminate the abnormal rhythm and return the heart rhythm to normal.

 

The symptoms of tachycardia include palpitations or fluttering sensations in the heart; lightheadedness, fainting spells or loss of consciousness, fatigue and weakness and a flushing sensation. The defibrillators monitor the heart rhythm and start to work only when the heart rhythm becomes abnormal.

Defibrillators usually deliver a strong electrical shock to the fibrillating heart without delay. Irreversible brain and other organ damages can occur if the defibrillator does not begin to work within minutes of a cardiac arrest. Most patients can potentially be saved if shocks are delivered quickly to convert the fibrillation to normal rhythm before irreversible brain damages occur.

The electrical shocks delivered by defibrillators can be mild or strong; it depends on what the heart requires. Most doctors will implant defibrillators in individuals with high risk of cardiac problems. In case of patients known to be at risk of developing life-threatening tachycardia, defibrillators can be implanted in their chests as a preventive measure to terminate tachycardia and fibrillation and avert cardiac arrest.

External defibrillators are available. They are usually present in every emergency room and they are used by physicians at the hospital during a cardiac arrest. External defibrillators usually need to be given by individuals who have been trained on it. Usually people who have done CPR courses know how to operate defibrillators.