Cardiac arrest

A halt in the pumping action of the heart that occurs when its rhythmic muscular activity ceases. The most common cause of cardiac arrest is a myocardial infarction (heart attack). Other causes include respiratory arrest, electrical injury, loss of blood, hypothermia, drug overdose, and anaphylactic shock. Cardiac arrest causes sudden collapse, loss of consciousness, and absence of pulse and breathing. The diagnosis is confirmed by monitoring the electrical activity of the heart by ECG. This distinguishes between ventricular fibrillation and asystole, the 2 abnormalities of heart rhythm that cause cardiac arrest. Ventricular fibrillation may be corrected by defibrillation. Asystole, the complete absence of heart muscle activity, is more difficult to reverse but may respond to injection of adrenaline.


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