First, an exercise stress test is a terrible name.  The word stress conjures up all kinds of ugly images.  Most people have enough stress in their life without having more in a test.  Although kind of clumsy, a more accurate name would be an “electrocardiographically monitored exercise test”.  This is a test that is done to evaluate people who have chest pain.   Coupled with the clinical picture, the physical examination, and the response to medications this test is a way to diagnose coronary artery disease before the arteries that supply the heart get stopped up all the way and cause a heart attack. Heart attacks are the leading cause of death in the United States.  The best way to illustrate how this test is used is to tell a story.

     A 52 year old gentleman came to the clinic much against his own wishes at the insistence of his wife and his daughter who was in nurse’s training.  He had been a smoker for many years.  He had not sought medical attention in over 12 years since he fractured his ankle playing softball.  He had been an athlete in high school and played city league basketball in the over 40 year old league.  Recently, he had noticed that he had to take himself out of the game because he was getting chest pain from playing basketball.  He knew that if he rested a few minutes, the chest pain seemed to go away and then he could play another few minutes before the pain recurred requiring a second or a third or a fourth rest.  The week before he was seen, he had been unusually fatigued and developed chest pain while he was shoveling snow off the walk even though it was only 4 inches of fluffy snow.  He didn’t know his blood pressure and he didn’t know his cholesterol.

     He described the pain as being in the middle of his chest sometimes going up into his neck but didn’t think it was a heart problem because the pain didn’t go into his left arm.  His blood pressure was 160/100, his cholesterol was seen to be 280 mg% (normal =200mg% or less) and a random blood sugar was found to be 210 mg% (normal = 110 mg% or less).  He had 4 major risk factors for developing coronary artery disease and now had symptoms that strongly suggested that parts of his heart were not getting enough blood for them to function normally.

     Normally, a heart pumps about five quarts of blood per minute.  A trained athlete running a 100 yard dash can pump as much as 20 quarts per minute.  A fifty year old, overweight diabetic, smoking, hypertensive, hypercholesterolemic, former athlete can be predicted to have a maximum cardiac output of less than ten quarts per minute.  When he would shovel snow or play basketball, his heart would have to pump more blood than the resting five quart per minute level.  In order to do that, his heart would have to work harder and would need more blood of it’s own to do its work.  If the coronary arteries that supply the heart with blood are stopped up, there is a limit to how much blood the heart can get to do its own work.   When the heart doesn’t get enough blood, it begins to hurt causing chest pain like that described by this gentleman.  When the heart is then allowed to rest, the heart doesn’t need to do as much work at that point, its blood supply in the resting state is adequate and the pain goes away in ten to thirty minutes.

     This gentleman was apprised of the situation and said he didn’t believe a word of it.  He didn’t feel that there was anything wrong with him except a little indigestion.  This is the perfect person to have an electrocardiographically monitored exercise test.

     In order to carry the test out, he came to the clinic one morning and received a tiny amount of a tracer material that would allow visualization of the blood supply to the heart.  This is a so called resting or background image.  He then had the electrocardiogram connected to monitor his heart.  He got on a treadmill and started to walk at 1.7 mph on level ground. This is a slow stroll and no real strain on the average person.  Yet his blood pressure went from 160/100 up to 190/115 by the first three minutes at this point.   This marked him as a “hot reactor”.  In other words in times of challenge, he overreacts in readiness even though there is no real physical need.

     After the first three minutes, the treadmill is raised to 10% grade and he continued to walk at 1.7 mph.  His blood pressure remained high during this time and by the end of the additional three minutes at this level, he was beginning to experience chest discomfort.  He said that it wasn’t the pain that he had had but there was a sensation in his chest.  The treadmill was raised to a 12% grade and the rate of walking increased to 2 1/2 mph.  This is a deliberate business-like walk, not really hurried.  After two minutes at this level, he experienced the chest pain that he described previously.  The electrocardiogram demonstrated that there were parts of his heart that were not getting enough blood for them to function normally.  At that point, a second tiny amount of tracer material was injected into his veins. This material ran through the heart and again outlined its blood supply.  Now it was seen that there were parts of his heart that were clearly not getting enough blood.  The test was stopped at this point even though he was not fatigued and said that if he had been shoveling snow he would have kept going even though he had the chest pain.

     To finish the story, he now had four major risk factors for development of heart disease, a clinical picture consistent with coronary artery problems and an exercise stress test that was clearly positive indicating that there were parts of his heart that did not get enough blood when he exercised.  He was referred on to the cardiologist where an angiogram demonstrated that he had significant obstructions in all three major coronary arteries.  Unfortunately, he underwent coronary artery bypass surgery but has since made a complete recovery and returned to normal activity.

     Fortunately, this gentleman did not have the hearing defects that some people do.  He did hear and understand that stopping his cigarette abuse was an important part of his care, taking the medicine to get his cholesterol down was important, that taking the blood pressure medications to get his blood pressure down was important and a weight loss program to correct his diabetic condition was important.  Now two years later, he has addressed all of the above and is still playing over 40 basketball.

     So what is an exercise stress test?  It is a test in which a person walks on a treadmill within their own capability to see if they have a heart problem.  People often say that they want to delay the test so they can “get in shape” to pass their stress test.  Actually, the test is most useful when the person is in poor physical condition.  Other people, say they don’t want to take the test because they know that their exercise capacity is too compromised.  The idea of the test is not to check how well a person can exercise.  Rather it is a test to see what happens to the person’s heart when they exercise within their own capability.  Thus, the idea of getting in shape for the test is not applicable.  As a last word, people often ask if they can stop when they want to.  Sometimes the doctor will encourage the patient to go a little further especially if a person works harder in their own world than they do on the stress test.  The doctor would like to know that the person is working at least as hard on the stress test as they do in their own world but patients are not asked to go beyond their own capabilities.  Other reasons for stopping the test include:  a drop in the person’s blood pressure, a development of chest pain, electrogram changes that are diagnostic of a heart problem, or the person reaching the maximum age related pulse.

     Exercise stress tests can be done at St. Mary’s Hospital in Pierre, and now can be done at the Gettysburg Medical Center.  By the time both scans and the test itself are done, it takes a better part of a morning to complete the test.

     Part two of this topic will be presented in next week’s column.  It will deal with the complexities of the interpretation of the test.  No test is infallible and exercise stress tests are sometime positive when there is no heart problem and sometimes they are negative when there is a big heart problem.  Discussion of how to interpret the test and who are good candidates will be placed in next week’s column.