(CPR) is a combination of rescue breathing
and chest compressions delivered to victims thought to be in cardiac arrest
. When cardiac arrest occurs, the heart stops pumping blood. CPR can support a small amount of blood flow to the heart and brain to “buy time” until normal heart function is restored.
Cardiac arrest is often caused by an abnormal heart rhythm called ventricular fibrillation
(VF). When VF develops, the heart quivers and doesn't pump blood. The victim in VF cardiac arrest needs CPR and delivery of a shock to the heart, called defibrillation
. Defibrillation eliminates the abnormal VF heart rhythm and allows the normal rhythm to resume. Defibrillation is not effective for all forms of cardiac arrest but it is effective to treat VF, the most common cause of sudden cardiac arrest.