Imaging Studies: Coronary Artery Disease and Atherosclerosis
Guest: Dr. Joseph Schoepf - Radiology
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I’m Dr. Linda Austin. I’m interviewing Dr. Joseph Schoepf who is Associate Professor of Radiology and Internal Medicine and a true expert in the area of imaging studies of the heart. Dr. Schoepf, we’ve talked some now about the new CT scan capability that we have, but let’s talk in more detail, if we could, about what you, as a radiologist, are looking for when you’re looking at the coronary arteries to see if there is disease. First of all, can you explain just what the coronary arteries are?
Dr. Joseph Schoepf: The coronary arteries are those very minute and small vessels that come off the aorta, the main vessel pumping blood through the body, and they supply the heart muscle. They’re very small. Every person has, typically, three of those major coronary arteries, or heart vessels, that supply different portions of the heart muscle with blood. The biggest threat, or complication, to those vessels is that they can get clogged, typically by atherosclerotic disease, stiffness of those heart vessels, so that the blood flow to different portions of the heart muscle is diminished. That’s what we refer to as a myocardial infarction, or heart attack.
Dr. Linda Austin: And what are the symptoms of that?
Dr. Joseph Schoepf: There are a number of ways in which heart attacks, or ischemia, insufficient blood flow, can manifest. A lot of people, particularly those with diabetes, are completely asymptomatic, so they can have massive heart attacks without feeling anything. Unfortunately, the most common symptom, or manifestation, of coronary artery disease is sudden cardiac death. These are people who have no idea that there’s anything wrong with their heart vessels, but they have a massive blockage of the one of those vessels which kills them almost instantly. And, unfortunately, to this day, that is the most common cause, or manifestation, of coronary heart disease.
Dr. Linda Austin: Now, I understand that you, as a radiologist specializing in this area, look at images of the heart from CT scans and angiograms which are a different kind of picture of the heart. In either case, you’re trying to get a feeling for whether there are blockages in the arteries. What, exactly, are you looking for? Are there particular criteria of how much blockage or are there some arteries that are worse if they’re blocked than others?
Dr. Joseph Schoepf: Well, there’s one coronary artery which supplies the left side of the heart with the most important portion of the heart muscle. This is referred to as the left main coronary artery, and it’s also, oftentimes, referred to as the widow maker, because it supplies such a large portion of the heart muscle. If there’s anything wrong there, it’s a very dangerous situation. So, this is the vessel that we’re most concerned about. Fortunately, this vessel is typically very large and relatively immobile, so with a CT scan, or CAT scan, of the coronary arteries, it is very easy to diagnose any major diseases of that major vessel.
Then, we have different coronary arteries that supply different portions of the heart muscle. What we typically look for in those heart vessels are signs of atherosclerotic disease of the coronary arteries, or arteriosclerosis. The most well known manifestation of coronary atherosclerosis is calcification. And we have different tests to test for calcifications, or atherosclerotic disease, of the heart vessels. The simplest application in that regard is coronary artery calcium scoring. This is a test that we offer and we can easily detect whether there are any calcifications in the coronary arteries. The best possible outcome of this test is if we don’t find any calcium, because it is extremely rare that a patient has significant coronary artery narrowing, or heart vessel narrowing, or blockages, in the absence of any calcium.
Dr. Linda Austin: So, let’s go a little bit deeper into that. In other words, then, when the artery begins to get blocked with these sort of gummy atherosclerotic, or fatty, plaques, they begin, also, to accumulate calcium, is that correct?
Dr. Joseph Schoepf: That is a somewhat simplified description but, in essence, that’s what it boils down to. The problem is that we know very little about how, exactly, atherosclerosis forms. We know very little about how those plaques get into the vessel wall. We know very little about how they progress over time. But, what you described is probably the most intuitive way of describing how atherosclerotic disease works.
Dr. Linda Austin: So, then, with this relatively simple test, this calcium scoring, you can determine if there are calcifications in the coronary arteries. How is that test done?
Dr. Joseph Schoepf: That test is done without any dye injection, so we do not really need any dye injected in the arm vein for that particular patient. What happens is, EKG leads are attached to the body, which record the patient’s heart rate. And, in synchronization with the patient’s heartbeat, the scanner table is moved through a CT scanner gantry, and we create tiny sections through the heart that allow us to detect calcifications, if they are there, or reliably rule out their presence, if they are not there.
Dr. Linda Austin: How long does that take, for the patient?
Dr. Joseph Schoepf: The test usually takes about a few seconds. So, it takes significantly longer to attach those EKG leads and get the machine ready and everything. The actual test takes about 5-10 seconds, and everything is over.
Dr. Linda Austin: So, it’s a simple painless test. Now, if a patient, let’s say, has a high calcium score, indicating that there is, in fact, a lot of calcium in these plaques, what is the next step?
Dr. Joseph Schoepf: Well, if a patient has a lot of calcium, what we typically do is compare that with the level of coronary artery calcium that can be expected in patients of the same age and gender. And, if the patient has an equal or lower amount, we’re typically not that worried. If the patient has a very high amount of coronary artery calcium, you may look into the overall history of that patient. You may want to look at their overall presentation. We know from the literature that calcium scores don’t go one on one with the overall burden of atherosclerotic disease. However, a high calcium score is an indicator that atherosclerotic disease of the heart vessels is at an advanced stage. So, you may want to throw that together with the family history of the patient, risk factors, such as smoking, and then come to an overall picture of what you would like to do. Typically, if a patient has an excessively high calcium score, we recommend risk modification, such as with lipid lowering therapy. There are a lot of drugs out there that can improve the cholesterol profile of a patient. We recommend aspirin, for example. These are all tools that we can use for risk modification.
Dr. Linda Austin: And, of course, for any patient, to quite smoking, if they are smoking, to keep their weight at a healthy level, and to eat a good diet.
Dr. Joseph Schoepf: Absolutely, all the things that are common sense.
Dr. Linda Austin: Dr. Schoepf, thank you so much.
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