This is part 3 of a 3-part series about hearts attacks. In part 1 we covered atherosclerosis. Part 2 dealt with angina pectoris.

This part deals with the real thing – the heart attack that can be caused by the plaques in the heart’s coronary arteries.

Danger level: High

What is it?

A heart attack (or myocardial infarction by its medical name) occurs when the blood supply to part of the heart is interrupted, causing the heart cells in that part to die.

Who gets it?

People in danger of having a heart attack are the same ones who have the risk factors for developing atherosclerosis (for a reminder, see part 1).

What causes it?

In parts 1 and 2 of this series, we explained about the heart’s arteries, which supply it with oxygen, getting blocked by plaque. We also mentioned that if they get narrow and the blood supply to the heart diminishes, a pain in the chest called angina can occur.

The plaque that builds up inside the artery can eventually burst, tear or rupture. When the plaque ruptures, the body recognizes this as damage to the artery. Remember what happens when you have a wound on your skin? Within a short time it clots, sealing down the wound so that blood won’t spill from it. The same thing happens here: The “wound” in the artery clots.

How does this clotting happen? Platelets are the cells in our blood responsible for clotting. They aggregate together, helping the clot form. The clot is called a thrombus.

You might think to yourself – “the body has done its job right. The wound in the artery is healed.”. But the clotting process here is actually what brings about the heart attack. The clot in the artery can lead to an occlusion of the blood flow inside the artery, causing blood to not pass in the artery anymore. This leads to blood not reaching where it should in the heart.

When blood doesn’t reach a part of the heart, that part doesn’t get oxygen. When this happens, the cells in that part start dying. When they finally die, they can’t grow back, and that part of the heart is lost and will not function anymore.

The time it takes for the cells to die is a few hours. If the condition is treated within that time frame, the heart can be saved.

This video shows the process visually -

How does it feel?

A heart attack feels like angina, but lasts more than 30 minutes and is not relieved by nitroglycerine or by rest. Here’s a reminder of the symptoms:

1. Pain, pressure, discomfort or heaviness in the chest. It can radiate to the left arm, the neck or the jaw.
2. Sweating, nausea, vomiting or dizziness may accompany the pain.
3. Rapid or irregular heartbeats may be felt as well.

How is it discovered?

There are a few things that can be done when you reach the ER to see if you have a heart attack:

1. ECG: You can read an explanation about that in part 2.
2. Blood tests: When the cells in the heart start dying, certain materials (called enzymes) start leaking out from them and into the blood. These enzymes are called troponins. When their level in the blood is high, this hints to a heart attack.
3. Coronary angiography – (see an explanation in part 2) can be used to visualize the arteries in the heart to see if they are blocked.

How is it treated?

Perfusion is a word that means blood coming into an organ. In a heart attack, blood is not reaching the heart muscle properly. In order to bring blood back into the heart, the artery needs to be re-opened. This process is called re-perfusion.

There are 3 ways to get the artery opened:

1. Percutaneous coronary intervention (PCI) – This is a long and complicated name, but the procedure is simple to understand. Remember when we spoke about coronary angiography being able to show your heart’s arteries?
   It can also be used to treat the arteries. The catheter which is inserted into the arteries is used to do one of two things. It can inflate a balloon, which will open the block in the artery. Then it can insert something called a stent – which is a tube inserted into the artery to keep it open.

   This video shows how it works:
   
2. Thrombolysis – In this procedure a material is injected into the blood vessels, which causes the clot to “melt”. This opens the heart’s arteries back. While it sounds easier than the first method, it’s not as efficient, and not everyone is suitable for this procedure.
3. Coronary artery bypass surgery (CABG) – Sometimes neither of the first two treatments fit. In this setting, a surgery has to be performed. In it, the chest is opened and the heart is exposed. The surgeon then takes an artery or vein from somewhere else in the body and implants it to the heart’s arteries. In this way, the occlusion is bypassed by a new, open, blood vessel.

Besides those, some drugs are given to everyone having a heart attack. They include aspirin (which stops the platelets from aggregating and so slows down the process), pain killers, oxygen and others.

What happens after treatment?

Without treatment, death rates are high for people who undergo a heart attack. But even with treatment, death can occur, especially before reaching the hospital. This is mainly due to complications that can occur as part of the heart attack, such as problems with the heart rhythm, failure of the heart’s muscle to pump properly, problems with the heart’s valves and others.

The bottom line – How do I avoid it?

The best way to avoid a heart attack is to prevent the process of atherosclerosis from happening (see part 1).

If you do have atherosclerosis or if you had a heart attack before, you can prevent it from happening by visiting your doctor. They will prescribe some drugs for you (including statins, beta blockers, aspirin, and others. All have been mentioned in this 3 part series). Taking these drugs regularly will lower your chances of getting a heart attack.

What next?

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