What is cardiac arrest?
A cardiac arrest is the cessation of normal circulation of the blood due to failure of the ventricles of the heart to contract effectively during systole. The resulting lack of blood supply results in cell death from oxygen starvation. Cerebral hypoxia, or lack of oxygen supply to the brain, causes victims to immediately lose consciousness and stop breathing. Cardiac arrest is a medical emergency with absent or inadequate contraction of the left ventricle of the heart that immediately causes
bodywide circulatory failure. The signs and symptoms include loss of consciousness; rapid shallow breathing progressing to apnea (absence of breathing); profoundly low blood pressure (hypotension) with no pulses that can be felt over major arteries; and no heart sounds.
Cardiac arrest is one of the greatest of all medical emergencies. Within several minutes, there is lack of oxygen (tissue hypoxia), leading to multiple organ injury. Unless cardiac arrest is quickly corrected, it is fatal.
During a heart attack, there may be disturbances in the heart rhythm. The most serious form of this is called 'ventricular fibrillation'. This is when the electrical activity of the heart becomes so chaotic that the heart stops pumping and quivers or 'fibrillates' instead. This is a cardiac arrest. It can sometimes be corrected by giving a large electric shock through the chest wall, using a device called a defibrillator. This is often successful in restoring a normal heartbeat and afterwards the person can do just as well as if they had not had the cardiac arrest.
If a person has a cardiac arrest, they lose consciousness almost at once. There are also no other signs of life such as breathing. This is the most extreme emergency. Unless someone starts cardiopulmonary resuscitation (CPR) within three to four minutes, the person may suffer permanent damage to the brain and other organs.
The most common causes of cardiac arrest are electrical problems in the heart with ventricular fibrillation representing the major type. In ventricular fibrillation, there is loss of coordinated ventricular contractions leading to immediate loss of effective output of blood by the heart, resulting in circulatory arrest.