FIRST AID

The heart is one of the critical organs of an animal's body, as it pumps oxygenated blood to feed the body's biological functions. The cessation of the heartbeat, referred to as cardiac arrest, is a critical emergency. Without intervention, death can occur within minutes of cardiac arrest since the brain requires a continuous supply of oxygen and cannot survive for long if that supply is cut off.

If a person is encountered in cardiac arrest, cardiopulmonary resuscitation (CPR) should be started and help called. Use of a defibrillator is preferred, if available, to attempt to restore a normal heartbeat; many public areas have portable defibrillators available for such emergencies. Usually, if there is enough time, the person can be rushed to the hospital where he or she will be resuscitated in the Emergency Department.

Electrical innervation of the heart in health is supplied by two closely intertwined mechanisms. The first mechanism is well demonstrated in electrical coil systole (interpreted by the electrocardiogram as QRS) as an individualized myocardial electrical tree initiated by the sinoatrial node. Secondary diastolic electrical control is posited to represent autonomic recoil control from the vagus nerve and cardiac branches and the thoracic ganglia.