What Are Myocardial Ischemia and Infarction?

I have been writing about things I experience in the hospital setting. Of course, we take care of many patients experiencing myocardial ischemia and infarction (a.k.a. heart attacks). I am aware that many in this community have experienced one or both of these, so I decided these conditions were worthy of a discussion here in this community.

So, what is myocardial ischemia? What are heart attacks? Who is at risk? How might they contribute to heart failure? What are the symptoms? What do you do when you experience these symptoms? Here is what to know.

Basic anatomy

Your heart is a muscle. Heart muscle consists of many cells. Like all cells, heart cells require oxygen to do their work. They rely on a series of blood vessels to supply them with oxygen called coronary arteries.¹

You inhale oxygen. Inside your lungs, oxygen enters your arterial blood system. This is a system of blood vessels that contain freshly oxygenated blood from your lungs.¹

This oxygenated blood enters one of four pulmonary veins. Two pulmonary veins exit the right lung and two exit your left lung. These are large vessels that carry oxygenated blood from your lungs to the left side of your heart. Your left heart then pumps this oxygenated blood to your aorta. This is the largest artery inside your body.^1-2

From there, oxygenated blood branches out to all the arteries in your body, and to all the cells of your body, including your heart. So, in effect, your heart is responsible for feeding oxygen to all the cells of your body, including itself.^1,3

The arteries that feed your heart are called coronary arteries. There are four main coronary arteries that branch off of the aorta. These in turn branch out to feed the various parts of your heart.^1,3

What is myocardial ischemia?

Myocardial ischemia basically means that a part of the heart isn’t getting enough oxygen. This can happen when a coronary artery (or one of its branches) is partially blocked.^{1, 4-5}

Ischemia may present with symptoms, such as angina (chest pain, pressure), neck pain, jaw pain, shoulder pain, arm pain, fast heartbeat, irregular heartbeat, shortness of breath at rest, shortness of breath with activity, feeling light-headed, fatigue, nausea, vomiting, and sweating.^5-6

Symptoms may vary from one person to the next. For instance, while one person may experience severe chest pain, another person may experience mild chest pain. Some people may present with no symptoms at all. This type of ischemia is often referred to as “silent ischemia.”^1,4,7,9

If you feel these symptoms, it is important to seek immediate medical attention. Prolonged and untreated ischemia can cause a heart attack. In many cases, ischemia can be reversed with immediate treatment, thereby preventing a heart attack.

Silent ischemia can be very troubling. This is because there are no warning signs to seek action. This may explain why 25% of heart attacks occur with no symptoms at all.^1,4,7

What is a myocardial infarction?

Myocardial infarction is a medical term for heart attack. It results from ongoing or prolonged ischemia. It’s caused by a coronary artery that is completely blocked or occluded. This prevents oxygen from getting to the areas of the heart fed by that coronary artery, causing heart tissue in that area to die.^1,7-9

Heart attack symptoms are the same as those listed above. It may damage or weaken heart muscle in such a way as to cause heart rhythm changes or even heart failure. It may also cause death. This is why it is so important to call 911 if you are experiencing any of these symptoms.¹ Another interesting tidbit here is that heart attacks are the most common cause of heart failure.¹⁰

What are the potential causes?

Potential causes of myocardial ischemia or myocardial infarction include:^5,6,11

• Coronary artery disease (CAD). This is also called atherosclerosis and is where plaque and cholesterol build ups up over time alongside the walls of the coronary arteries. This causes the lumen (opening) inside these arteries to become narrow. This narrowing causes resistance to the flow of blood, slowing it down. This can make it so not enough oxygenated blood gets to heart tissue. This is the most common cause of ischemia and heart attacks.
• Blood clots. Here, parts of plaque from CAD break off. These form clots that can obstruct coronary arteries.
• Vasoconstriction. The coronary artery may spasm where the plaque is present.
• Anemia. Not enough blood to carry an adequate supply of oxygen to the heart.
• Hypoxemia. There is enough blood, but not enough oxygen in arterial blood. Again, this prevents an adequate supply of blood from getting to the heart. This may be due to severe flare-ups of asthma, cystic fibrosis, or heart failure.

What to know

If you call 911, you will be rushed to the emergency room. If you drive yourself and say you are having chest pain, you will be sent right to the emergency room. Once you arrive, our doctors and nurses are specially trained to diagnose and rapidly begin treatment.