A heart attack occurs when blood flow to the heart is obstructed. This obstruction of blood flow is usually caused by plaque that forms in the blood vessels (coronary arteries) that supply blood to the heart from a buildup of fat, cholesterol and other substances. The obstruction of blood flow can lead to damage or necrosis of part of the heart muscle. Heart attacks, also known as myocardial infarction, are diseases that can be fatal, but their treatment has improved greatly in recent years. Once you suspect you are having a heart attack, it is important to call 911 or seek emergency medical help. Common signs and symptoms of a heart attack include: 1. Pressure, tightness, pain, crushing or unbearable sharp pain in the chest area or upper extremities, which may also spread to the neck, jaw or back. 2. nausea, indigestion, heartburn or abdominal pain 3. shortness of breath 4. cold sweats 5. fatigue 6. dizziness or sudden onset of vertigo The manifestations of a heart attack can be varied, and not all patients have the same symptoms, and the severity of symptoms varies. Some patients have only mild pain; others have very severe pain. Some patients are asymptomatic, while others have cardiac arrest as their first manifestation. However, the more of these signs and symptoms are present, the greater the probability of a heart attack. Some heart attacks occur suddenly, but for many patients, there are early warning signs hours, days, or weeks before the onset of the attack. The earliest warning manifestation may be recurrent chest pain (angina) that is triggered by exercise and relieved by rest. The cause of angina is a transient decrease in blood flow to the heart. A heart attack is different from cardiac arrest (which occurs when a disturbance in the electrical current disrupts the pumping process of the heart, thus preventing blood flow from reaching parts of the body other than the heart). A heart attack may lead to cardiac arrest, but it is not the only cause of cardiac arrest.