A heart attack occurs when a coronary artery becomes completely blocked for a period of time. The blockage stops the flow of blood to a part of the heart muscle. Without oxygen-rich blood, the heart muscle will be damaged. This damaged area will no longer work like normal heart muscle.

Injured heart muscle heals gradually after a heart attack. In time, a scar will form over the damaged muscle.* You need to limit your activity while the scar tissue is forming. As the scar becomes stronger, you will be able to resume more and more of your normal routine.

• The scar normally forms in 4 to 6 weeks after a heart attack.
• If the heart attack has damaged a large part of your heart, you may have to limit your activities for a longer period of time, perhaps always.

* Over time, as coronary artery blockages were developing, blood flow to the heart muscle was reduced. The reduced flow may have caused small artery branches (collaterals) to open and allow some blood flow to the affected area. This process, called collateral circulation, may
help, but is not always enough to meet the heart’s needs.

Coronary arteries can be blocked in 3 ways

Atherosclerosis
Fatty cholesterol deposits (plaque) build up in the artery to the point where little blood can flow through to nourish the heart.

Thrombosis
This is the most frequent cause of heart attack. A blood clot forms in an artery already narrowed by fatty plaque, blocking the flow of blood through the vessel. In many cases, plaque along the artery walls may rupture or tear (plaque rupture). When this happens, blood clots form and block the flow of blood.

Spasm
The coronary artery can spasm or constrict, limiting blood flow.

What does it feel like to have a heart attack?
Heart attacks feel different from person to person. They can also feel different to the same person from one heart attack to the next. Some people never experience any symptoms. (This is called a “silent” heart attack.)

Though pain and discomfort may occur in the same area as angina, heart attack symptoms are usually more severe than angina and different in an important way: Heart attack symptoms will not go away after rest and taking 3 doses of nitroglycerin (3-5 minutes apart).

Common heart attack symptoms

• pressure, squeezing, tightness, burning or aching in your chest, jaw, neck, shoulders, back or arms
• indigestion, nausea or vomiting
• shortness of breath
• a feeling of general weakness
• sudden sweating
• a fast, pounding heartbeat (This symptom is more common for women than men.)