What is Angina?
Across the years, people have used many words to describe the pain that comes from blocked arteries in the heart. I have heard “acute angina”, “angina pectoris”, “angina”, “chest pain”, “chest pressure”, and many permutations of chest aching/squeezing/fullness/dullness/heaviness to describe what happens when there is inadequate circulation to the heart muscle to meet its needs.
For the purpose of this discussion, we will call it “angina” and we will define it as pain originating from the heart when the blood supply to the heart muscle is insufficient to meet the demands of the heart muscle. It is a supply/demand mismatch.
There are several facts that you need to know to understand how the heart receives oxygen.
Coronary arteries arise off the aorta immediately after the aorta leaves the heart. This insures that the first organ to get oxygenated blood is the heart. Might be self-serving, but that’s how we were created.
The heart only receives blood during diastole – the relaxation phase between contractions. So diastolic blood pressure is the blood pressure at which the heart muscle receives oxygenated blood.
While other regions of the body extract a “medium” percentage of oxygen out of the blood, and retain the capability to increase the amount of oxygen they extract, the heart muscle always extracts as much oxygen from the blood as it can. While this seems more efficient than leaving oxygen on the blood cells, it limits the heart’s options to increase the oxygen supply when it needs it.
If you decide to perform some physical activity (climbing stairs, carrying a heavy item) the only thing the heart can do to increase the amount of oxygen it receives is to speed up the pulse rate. This works… to a point. If the heart speeds up too fast, there is not time for the blood to percolate into the heart muscle between beats. The innermost muscle of the heart is then deprived of blood, essentially choking it.
When the body increases its activity level, it signals the heart to beat faster, and more forcefully, to try to keep up with the higher oxygen demands of the body. The heart responds faithfully without complaining.
If there is a blockage in a coronary artery, or multiple blockages, these fixed blockages limit how much blood flow gets through those arteries.
No matter what signals the body is sending the heart to pump harder or faster, the heart is going to get a fixed amount of circulation itself, limited by the blockage in the coronary artery.
The demand (from the body) keeps rising, but the supply (from the coronary artery) is fixed. The supply/demand mismatch occurs, and a cascade of events begins that leads to lactic acid buildup, anaerobic metabolism, increased wall tension of the heart muscle, inadequate oxygen to the heart muscle and, if the situation does not end by the body taking a rest, can result in a heart attack, or even worse, cardiac arrest.
There are ways to improve the “supply” so it can meet the “demand”. Medications like nitroglycerin can dilate arteries, to permit more blood to flow through them. We often prescribe nitroglycerin for this purpose. We can purposely slow down the heart rate with medication called a beta blocker so there is more time during diastole, between beats, for the heart muscle to receive blood. We can remove offending agents that cause the coronary arteries to constrict – things like tobacco, caffeinated beverages, and certain migraine medications. The easiest way to correct the supply/demand mismatch is to reduce the demand – stop the physical activity, and rest. Since being in a stressful situation can increase the “demand” by triggering the fight-or-flight stress hormones, an important way to reduce the “demand” is by removing yourself from a stressful situation.
Why is it important to see a doctor if you get angina? Angina is a warning sign. It is like the “check engine” light on your car dashboard. Angina is a signal to you that something really bad is going to happen if you don’t make some serious life changes. These changes can be in diet, exercise, medications, habits, or jobs. The “something really bad” is a heart attack. A heart attack occurs when the heart muscle sustains actual damage from inadequate blood supply.
Usually this occurs in an artery with an existing 40-50% blockage where an “unstable flap” lifts off the artery wall and occludes the entire artery, preventing blood flow down that artery. The unstable flap may be triggered by smoking, stress, high blood pressure or oxidative stress (omega 6 fats contribute to oxidative stress).
What should you do if you get angina? Stop whatever activity you were doing and sit down to rest. Call your doctor ASAP. Avoid smoking. If the angina doesn’t resolve with 15 minutes of rest, you need to chew 4 baby aspirins, call 911 and go to the nearest hospital.
If your angina does resolve with rest, call your heart doctor and make an appointment that week. His staff will draw blood for labwork, apply stickers to your chest to perform an electrocardiogram, obtain a chest x-ray, examine your heart, and arrange heart testing to determine if you have had injury to your heart. You may need a heart catheterization to look at your coronary arteries, to determine if you need a stent of a bypass surgery.
Don’t ignore the warning signs. Angina can lead to a heart attack, which can be fatal. There is no sense trying to be a hero or appearing tough, when your heart and your life may be at risk. Take the time to learn what you can do to prevent angina, and get started on a healthier life. Your doctor will be able to help guide you.