In this diagram, the top artery is healthy. There is no plaque to restrict the flow of blood or cause angina. The middle diagram shows an artery with a substantial blockage that is limiting blood flow. It is likely that this person may suffer angina, which may include chest discomfort, shortness of breath, fatigue and dizziness. These symptoms indicate that the heart muscle is not receiving enough blood to keep it healthy. The bottom diagram shows a completely blocked artery. No blood is able to flow through the artery. When an unstable plaque ruptures, blood clot forms on top of the plaque, seen here as the red particles. The clot completely blocks the artery suddenly. This is a serious condition that may lead to a heart attack or stroke.
Angina is a problem of supply and demand. Your heart (coronary) arteries supply the muscle of the heart with oxygen and nutrients. Your heart is a muscle that beats all day, every day. The amount of work your heart has to do is determined by how hard it is to pump your blood around the body. That is the demand. As your blood pressure gets higher, your heart has to work harder to move the blood through. As your heart beats faster, that also increases the work. Exercise, anxiety or fighting with your in-laws all are examples of things that increase your blood pressure and heart rate, thus increasing the demand for oxygen and nutrient-rich blood to feed the heart muscle and meet the demand. With normal, wide open coronary arteries, the supply of this blood is not a problem.
When blockages have built up in your coronary arteries blocking most of the blood flow through the artery, there is a limit to the supply. The heart is pretty efficient, so when you are doing your usual activities, it does not demand much. But when exertion increases the work the heart needs to do, the demand for oxygen goes up. The blocked artery cannot increase supply to meet the demand, and this causes angina. And, when you sit down and stop exerting yourself, the demand goes down, supply and demand match and the angina goes away.
Blockages that have built up over time can meet a certain amount of demand, but if the demand is too great, angina occurs. This type of blockage causes stable angina; it allows for a steady reliable amount of work before it can’t keep up with the supply from the coronary arteries.
But the blockages of atherosclerosis do not grow at a steady rate like our hair or fingernails. Most commonly, they grow as a result of ruptures in the plaque. This is more similar to pimples popping up overnight. When one of these plaque ruptures changes a relatively non-obstructive blockage to a tightly obstructive blockage, supply and demand don’t match again. But when this happens the problem is a lack of supply instead of too much demand. That is why unstable angina is different. It is not related to how much exertion you do. It may happen at rest, and stopping to sit down does not make it go away. The nature of the blockage has changed and the efficient heart may not have enough supply to meet the demand--even for sitting still. That is why unstable angina is an emergency.
Coronary artery disease (CAD) is caused by atherosclerosis, the process behind the supply and demand problem that causes angina. There is no cure for CAD and atherosclerosis but it is possible to slow the process with lifestyle changes and medications. If necessary, blocked arteries can be opened with angioplasty and stenting or open-heart bypass surgery. So, If you have CAD, it is very important that you work with your cardiologist and other members of your healthcare team to develop a treatment plan to relieve your angina and reduce your risk of heart attack, stroke, and other serious problems caused by atherosclerosis, including peripheral artery disease (PAD), which can cause debilitating leg pain when you walk, as well as kidney (renal) artery disease, which can cause kidney damage and high blood pressure.
Because angina is most often caused by CAD, most of the risk factors are the same. They include:
It is also helpful to know what triggers your angina symptoms. Use the SecondsCount Tracking Your Angina Worksheet to record what you were doing each time before you had angina symptoms.
Here are some common triggers to monitor and avoid if possible:
- Very hot or very cold temperatures
- Big meals
- Physical activity
- Emotional stress
- Drinking (alcohol)
Of course, it is impossible to avoid every single trigger and it’s not good for you to give up all physical activity. In fact, regular exercise is one of the best things you can do to treat your heart disease! Talk to your doctor about your options for staying active while treating your angina. If you have not been exercising regularly, talk with your doctor before starting your program to good heart health.
You can’t change a history of heart disease in your family, but you can change what you do today and tomorrow to slow the process of atherosclerosis and feel better. See Treatment of Angina for more tools and information on making changes in your life, such as maintaining a healthy weight and eating the right foods to do everything you can to reduce your risk factors.