Final answer:
Cardiac arrest is a critical emergency where the heart stops pumping blood, while a heart attack (myocardial infarction) is caused by blockage in the coronary arteries leading to tissue death. Arrhythmias are irregular heartbeats which can sometimes cause cardiac arrest and may require defibrillation.
Step-by-step explanation:
Cardiac arrest refers to the sudden loss of heart function, where the heart is unable to pump blood effectively or at all. It is a critical emergency that requires immediate medical intervention to prevent death. Often confused with a heart attack, which is technically known as myocardial infarction (MI), the two terms represent different conditions. A heart attack occurs when there's a complete blockage of the coronary arteries, causing death of cardiac muscle tissue due to lack of blood flow. The blockage is often caused by a buildup of plaque, a mixture of lipids, cholesterol, fatty acids, and white blood cells. On the other hand, cardiac arrhythmias are abnormal rhythms of the heart that can range from too slow to too fast or irregular, and might be life-threatening, sometimes necessitating the use of a cardiac defibrillator to restore normal rhythm.
Moreover, in cases of severe arrhythmias like ventricular fibrillation, defibrillation is essential as it can reset the heart's rhythm. This procedure can be life-saving and is typically administered through an automated external defibrillator (AED) in emergency situations. While cardiac arrest can result from a heart attack or arrhythmias, the direct cause is the heart's inability to pump blood, not necessarily a blockage.