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Transcripts: 514-1 and 514-2
Week: 514.1 Guest: Louis Grenzer, M.D. Topic: Heart Stress Test - Part One Host: Richard Roeder Producer: Ed Graham
NEMA : This is the first half of a discussion on the cardiological stress test with cardiologist Dr. Louis Grenzer from Baltimore, Maryland.
NEMA : Dr. Grenzer, one thing that a lot of people who go to their cardiologist hear at some time of their lives is a "stress test." Would you describe what a stress test is and why you would ask that a patient have a stress test in the first place.
GRENZER: Let me first answer why we would do a stress test and by far the most common indication for doing a stress test is a patient presenting with chest pain. Now if the pain is clearly coming from the heart by the history and even by the resting EKG, we still may want to do a stress test to quantitate how much exercise you can do before getting changes and before getting chest pain, however, if you have a typical chest pain so that we're not sure whether it's the heart, it is of course very important to exclude that because that is a serious condition requiring further treatment and investigation. So chest pain would be the most common indication. There's a number of other indications. Nowadays we're doing a lot of stress tests in people just to screen them for heart disease, particularly high risk patients. There's a tendency nowadays to do stress tests in people in high risk occupations. I'm seeing a lot of patients who've had stress tests as part of a routine examination if they're a fireman or a policeman and an older person or a middle-aged person who wants to start exercising, we may do a stress test to make sure that they can do that safely. Those are the major indications for why we do a stress test. There are other ones, of course, and how do we do it? Well, a stress test first involves taking a history from a patient and examining the patient to make sure that there's not some reason we shouldn't do the stress test. For instance, a patient with blockage of his aortic valve would not be a patient that we would ordinarily do a stress test on because it might be dangerous. A patient with severe anemia probably should not have a stress test until that condition is corrected. As a matter of fact, any unstable condition is a reason not to do a stress test. Get the patient well first from his pneumonia or whatever other unstable condition there is and then consider doing the stress test. Once we've done that, how do we do a stress test? First we do a resting EKG to make sure that you haven't, for instance, had a recent heart attack which would be another reason not to do it and then, if that resting EKG is satisfactory, we hook the patient up to an EKG machine with electrodes that are pasted on so that they're not going to fall off in the middle of the test if you start perspiring or something and then we put you on a treadmill, we start it off at a slow rate of speed and a slight elevation. We exercise you for three minutes at that level and then we increase it to a higher speed and a higher elevation aiming at a specific heart rate which is the target heart rate for you determined by your age and sex and of course we might have to stop the test anywhere along the line if you get symptoms, if you have EKG changes, if the blood pressure drops too much or goes up too much but if those things don't happen, we keep exercising you until we at least hit that target heart rate.
NEMA : Join me for the second half of my conversation on the heart stress test with Dr. Louis Grenzer.
Week: 514.2 Guest: Louis Grenzer, M.D. Topic: Heart Stress Test - Part Two Host: Richard Roeder Producer: Ed Graham
NEMA : This is the second half of a discussion on stress testing the heart with cardiologist Dr. Louis Grenzer.
NEMA : Is there any kind of preparation out of the ordinary as far as diet or medication or anything that is required on the patient's part leading up to a stress test?
GRENZER: Not a whole lot. We ask people of course to come with comfortable clothing, shoes that are not going to slide and so forth so they can perform the exercise. Ordinarily I would not tell a patient that he can't eat that morning. We don't like someone to come immediately after eating, for instance, a large breakfast or lunch and pretty much, that's all you have to do is show up without having just eaten a large meal and in comfortable clothing that you'll be able to do the exercise in.
NEMA : On the average, and I realize there are probably variations for various reasons, but on the average how long does it take from the time a patient starts the stress test till it's completed?
GRENZER: Well of course, there's a certain amount of time it takes to actually hook you up to the EKG machine which would take maybe 10 minutes or so and then once we start the exercise, each stage is three minutes. A younger person, for instance, who is in good shape might go through four stages which would be 12 minutes and then we keep recording the EKG for an additional six minutes to make sure there aren't any late changes so that it would really in a healthy person maybe the total time, from the time you begin the exercise to the time when we're ready to unhook you would be maybe 18, 20 minutes. An older person or a person who because of disease is not able to do that much exercise, of course the test would be reduced by that amount of time.
NEMA : Now once you've completed a stress test on a patient, tell me what you learn from it and what kind of data you're looking at to determine the next stage in the process, whether that's treatment or no need for treatment.
GRENZER: The most important thing we're looking for is to see whether the patient has coronary artery disease, whether we have evidence by the results of that stress test that the heart, with exercise, is not getting enough oxygen which would ordinarily indicate there's a blockage somewhere in one of your arteries. The way we determine that is by symptoms that might develop while you're exercising such as chest pain or shortness of breath and then correlating those symptoms with changes in the waves on the EKG. When the heart doesn't get enough oxygen, the waves on the EKG change and if that happens at about the time or a little before you get chest pain, that would be a positive test. In some cases, there's also an additional part of the test. In some cases, we inject a slightly radioactive material, usually thallium, into your vein and then after the exercise is completed, we take pictures of the heart. If part of your heart is not getting enough blood flow during that test, a hole will form there which indicates that part of the heart is not getting enough oxygen. Later on, we take some late pictures and if that hole fills in, it means that that's an area that was temporarily not getting enough blood flow. If the hole does not fill in, it means you have a previous heart attack, a previous area of damage, that there's a scar there that is not viable muscle tissue in the heart.
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