A heart attack is a medical emergency that occurs when blood supply to part of the heart is suddenly cut off.

The heart muscles are supplied by the coronary arteries, which branch off from a major artery called the aorta. Heart attack occurs when one or more of the coronary arteries becomes blocked. This lack of blood supply and oxygen can cause injury to the heart muscle and if supply is prevented for more than 20 minutes, the part of the muscle tissue failing to receive blood may die. The medical term for a heart attack is myocardial infarction or MI.

Symptoms

• Chest pain – The chest may feel tight, pressured and heavy as if it is being squeezed
• Pain in other areas – The pain may radiate to other parts of the body such as the arms (usually the left arm), the neck, jaw, back and abdomen
• Feeling dizzy or lightheaded
• Sweating
• Shortness of breath
• Nausea and vomiting
• Coughing or wheezing
• Severe anxiety that is often described as a sense of impending doom

Not all chest pain indicates a heart attack. Indigestion commonly causes chest pain and can be mistaken for a heart attack, if severe. Conversely, a mild heart attack can be mistaken for indigestion. Some cases of heart attack are completely painless, particularly among the elderly, women and people with diabetes.

Diagnosis and treatment

A diagnosis of heart attack is based on the findings of an electrocardiogram (ECG). People admitted to hospital with suspected heart attack will be given an ECG within ten minutes of arrival. An ECG machine records the electrical signals generated by the heartbeat and a doctor can interpret this information to assess how well the heart is functioning. The treatment approach to heart attack depends on the type of heart attack the patient has had. Segment elevation myocardial infarction is the most severe form of heart attack and a patient with this condition will immediately be assessed for treatment to unblock the coronary artery.

The surgical procedures available to treat heart attack include coronary angioplasty and coronary artery bypass graft. Medications that may be administered to break down the clots include reteplase, alteplase, and streptokinase.