The ‘Why’ and ‘When’ of Getting a CT Angiogram

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A computer tomography angiogram, otherwise known as a CT angiogram, is a mouthful to say, but this procedure can be a very useful tool for patients having heart problems.

You may have heard of people getting CT angiograms, or regular angiograms, and wondered what this was, why it’s done and if you need to have one.

Dr. John Lesser, a cardiologist from Minneapolis Heart Institute®, is here today to tell us about this procedure, who makes a good candidate and what other options patients might have now and in the future.
The ‘Why’ and ‘When’ of Getting a CT Angiogram
Featured Speaker:
John Lesser, MD
John Lesser, MD, FACC, FASCI, FSCCT is the director of cardiovascular CT and MRI at Minneapolis Heart Institute® at Abbott Northwestern Hospital. He was the past president of the Society of Cardiovascular CT. He has 27 years of experience diagnosing and treating patients with cardiovascular diseases. Lesser also values the importance of research and he has been involved in over one hundred studies aimed at improving the quality and level of cardiovascular care offered to patients.

Learn more about John Lesser, MD
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Transcription:

Melanie Cole (Host):  A computer tomography angiogram, otherwise known as a CT angiogram, is a mouthful to say but this procedure can be a very useful tool to patients having heart problems. My guest today is Dr. John Lesser. He is a cardiologist and the Director of Cardiovascular CT and MRI from Minneapolis Heart Institute. Welcome to the show, Dr. Lesser. To begin, tell us what a CT angiogram is.

Dr. John Lesser (Guest):    Sure. Thank you. It’s nice to be here.  A CT angiogram is a test that is done generally as an outpatient. You will require an IV. You get into a CT scanner and the scanner is a special kind of scanner that is very, very fast so it can stop the motion of the heart. You inject IV dye, or contrast, in the IV and then by timing it properly, you fill up the arteries of the heart. You can see the lining of the wall of the arteries of the heart and the area that carries blood. So, you look for blockages as well as plaque that is in the wall of the artery.

Melanie:  Is this considered an invasive procedure and does it hurt?

Dr. Lesser:  Good point.  It is a non-invasive procedure, which is good. You might feel hot when they give you the contrast. It wouldn’t hurt except you have to put an IV in.

Melanie:  Once you’re doing this and, because you’re in a CT scanner, are you then able to follow up with an angioplasty at the same time or is that a whole separate procedure?  

Dr. Lesser:  Right. That’s a whole separate procedure. What a coronary CT angiogram is designed to do is to make a diagnosis. Is your symptom related to the heart; and then, how bad is it and where is it? Or, are your symptoms really from something else? The idea of being able to fix the problem you have to be in a completely different spot and that would be during an invasive procedure.

Melanie:  How is a CT angiogram different than the standard angiogram?   

Dr. Lesser:  In a standard angiogram, you numb the skin in the leg or the arm and you thread a tube up in your artery, not in the vein. The tube then gets up into the arteries that feed the heart. Then, you inject contrast directly and that outlines the arteries and you look around at multiple angles to see where a blockage might or might not be. The ability to see the blockage is very, very good when you do a direct injection. The coronary CT angiogram is a little different. That’s where you inject it in a vein. The contrast floats around the body and then you time it properly and you’re able to see the arteries themselves. The value, in addition, with the CT is you can see the wall of the arteries. With the invasive angiogram, you see the inside of the artery where the blood flows and you can get a better sense, sometimes, of what the long-term risk might be of a future heart attack by getting the CT angiogram as opposed to the invasive angiogram. The invasive angiogram is designed to make a definitive diagnosis – do you have severe blockage--and to be in a position to fix it at the same time.   

Melanie:  What a wonderful explanation. It’s absolutely fascinating. How do you determine if a patient should receive the CT angiogram? Are there certain parameters by which you go where you can tell somebody, “I’d like to do this first”?   

Dr. Lesser:   Yes. If you don’t know for sure that the problem is from the arteries of the heart and that it needs fixing, you’ll do the non-invasive test first because there’s no risk, or minimal risk. By doing the noninvasive test, then you can make your judgments much better educated. Sometimes, all you’ll need is medication and then you don’t need to go on to the next step even if the blockage is the cause of the symptoms.  

Melanie:   If a patient doesn’t have any symptoms but they are curious about their risk of heart disease, would they get this type of angiogram? How do you determine whether or not? Could this become a new screening method, Doctor?

Dr. Lesser:   That’s a really good point. When you do a screening test, there are different things about a test that you need. One, when you do a screening test you don’t want to be exposed to anything that might cause a problem because you are really doing this for large segments of the population. When you do a CT angiogram, you have to give angiogram dye and there are some people who react to that. Right now, if you have no symptoms, probably the best way to access the long-term risk you might have would be from a calcium score which is a CT scan without contrast.  If you have symptoms, that’s when adding the contrast adds the extra value.

Melanie:   As a researcher how do you see this technology changing? What do you see happening in this coming bunch of years?  

Dr. Lesser:   There are things that are going on right now. First, what a CT angiogram does it gives you the anatomy.  It shows “does the wall have plaque; does it have blockage”, but it doesn’t say “does the blockage limit flow to your heart”. We just make an assumption about that. Now, there is something called an FFR-CT. What we do is we get the CT information, we send it and analyze it through a super computer and a special technique and that tells us “is the blockage able to limit blood flow to the heart”. Not just “how does it look”, but does it actually limit blood to the heart. It is very, very accurate. It is something done by post-processing information instead of having to do something extra to a patient.

Melanie:  Are there some limitations of CT angiography?

Dr. Lesser:   Yes, there are. Sometimes you have so much calcium in your artery, you can’t see through it because calcium is very bright. At a certain point, it is not worth doing and we often would check to see what your calcium level is in the artery by a quick picture before we give the IV dye or contrast. Other times, if you can’t cooperate – if you’re moving around, you can’t hold your breath, or your heart rate is very, very fast – those are other reasons why the scan would not have the right quality.   

Melanie:   So then, talk about the results just a little bit, doctor. Who interprets those results? What goes on with follow up? What do you want patients to know about after care?

Dr. Lesser:   Good point. The person who interprets the results is someone who is already skilled and trained to do so. This requires special training. It can be either a radiologist or a cardiologist, but if it is someone who doesn’t have special training in reading the heart arteries, then it’s not a very good way to go. That is a very important part of that. Oftentimes these people will help to design the scan so you get the right information. That’s another important thing. It’s not as simple as going to get a CT scan of the abdomen.  The general set up has to be very specific for the heart. After you get that information, then the patient has to understand “what does this all mean” and that requires, really, I think, a conversation with your doctor who gets the information, who will understand what the comments are when they talk about the CT to try to make a judgment.   Do you need to be on medication to prevent a future problem like cholesterol medication? Or, are you perfectly fine and your risk would be extremely low in the next 15 years? There can be a wide range of recommendations based on what we see.

Melanie:   This is great information, doctor.  Just in the last few minutes, give patients and listeners your best advice for those who think they might have heart disease; who would like to be checked and who are considering a CT angiogram.

Dr. Lesser:  If you have no symptoms and you might have some risk factors, the calcium score – and that doesn’t have the contrast – would be your first best step if you’re going to have a scan to access your risk. If you have symptoms and you want to know “do I have plaque and is the plaque the source of my symptoms”, then the CT angiogram makes sense. I would make sure that you go somewhere that is familiar with doing that and that you have a situation where someone can explain the results to you and put it in context. So, you would know “is this really related to my current problem and what do I do for the long-term”.   

Melanie:  Thank you so much for being with us. You’re listening to The WELLcast with Allina Health. For more information you can go to AllinaHealth.org. That’s AllinaHealth.org. This is Melanie Cole. Thanks so much for listening.