What can EKGs, stress tests, and other diagnostic tests tell you about your heart?
What Does a Stress Test Measure?
The main goal of a stress test is to see if the blood flow of the heart changes when there is increased demand for blood (which happens when a person is working hard—like when exercising). The plaques I discussed in my last article can narrow the blood vessel. The narrowed vessel may be able to supply the heart with blood at rest, but under increased demand (like with exercise), the heart can become starved for oxygen.
What Does an Abnormal Stress Test Mean?
An abnormal stress test usually indicates there is a narrowing of an artery supplying blood to the heart, although there are some cases where the test is abnormal on someone with a normal heart. But please be aware that a negative stress test does not mean there is nothing wrong either; you can still have less-severe narrowing of the arteries that can still lead to a heart attack. But it is reassuring if the test is normal.
What is a Cardiac Catheterization?
If the doctor thinks there is a high likelihood of narrowed blood vessels, even if a stress test or EKG were normal, the next step is a cardiac catheterization. In this diagnostic test, the coronary arteries are injected with dye and narrowing is identified.
A heart with narrowing in the coronary arteries is much more likely to have trouble in the future: either from a heart attack or from a fatal heart rhythm caused by decreased blood flow. What is done about the narrowing depends on how bad it is. A normal catheterization means that the likelihood of a heart attack in the near future is very low.
What is a Heart Calcium Score?
One test that is still quite controversial is the coronary calcium score. This test is a CT scan of the heart that looks for small amounts of calcium in the coronary arteries. That calcium isn’t a problem in itself, but it is a marker for the presence of fatty plaques that can lead to heart attacks. If calcium is absent from the coronary arteries, the chance of there being significant plaque build-up is very low.
So why is it controversial? First off, it exposes the person to a lot of radiation. That radiation is not dangerous in itself, but if added to other tests over a person’s lifetime, scientists fear that it could do harm. The second problem is that we don’t know how to interpret it. It’s not hard on either extreme: either a score of zero, or a very high score – indicating a lot of plaque. But what happens if someone low-risk gets a score that is low, but not zero? We really don’t know.
The only time I have found these tests useful is if I am trying to decide if someone needs to start on medication for cholesterol or blood pressure. The main purpose of these medications is to reduce future risk of heart attack, so the presence of heart plaque is key in my decision-making process. Don’t get it done unless your doctor recommends it.
What is an Echocardiogram?
The last diagnostic test I am going to mention is the echocardiogram, or the sonogram of the heart. This test uses sound waves from a probe placed on the chest to make a picture of the heart while it’s beating.
What Does an Echocardiogram Measure?
Conditions that are picked up by an echocardiogram include:
Past heart attacks
Valve problems, such as mitral valve prolapse
Congestive heart failure – which is when the heart is damaged enough that its pumping can’t keep up with the body’s demands.
Inflammation of the sack that surrounds the heart.
They do not, however, tell if someone is at risk for a heart attack or even if they have any plaque on their coronary arteries. Coronary artery catheterization is the right test for that.
So once bad stuff is identified, what can be done about it? That’s information for a future article.
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Let me once again remind you that this podcast is for informational purposes only. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.
Catch you next time! Stay Healthy!