Hi Shannah - glad it was timely for you. I've copied it here in case that helps you print it out.
And Otis - great to know that someone has experience with this. Thanks. sb
Pharmacological Stress Test
Philipa Corning, Ph D
Vice President
Quest 61, 2003
In the last issue of Quest, the article entitled, ME/CFS Post-Exertional Malaise/Fatigue and Exercise by Marjorie van de Sande, described abnormal responses to exercise exhibited by ME/CFS patients and the consequent dangers of exercise stress tests for these patients. In view that some ME/CFS patients may require a stress test in special circumstances, such as following a heart attack, this article presents an alternative stress test, which is safer for ME/CFS patients.
Stress Tests
The purpose of any type of stress test is to determine if the heart muscle is getting the blood supply it needs in order to function properly. When your heart works harder, it requires more oxygen, which is carried by the red blood cells. If it does not get the required increased oxygen during increased workloads, you experience chest pain, irregular heart rhythms (arrhythmias) and other problems.
Usually a treadmill stress test is administered. While appropriate for many people, the article in the last issue of Quest described abnormal, adverse reactions to treadmill stress tests, which can cause severe relapses in ME/CFS patients. The treadmill stress test is inappropriate for ME/CFS patients as it has been demonstrated that it can cause decreased cerebral blood flow, cerebral oxygen, body temperature, breathing irregularities, impaired oxygen delivery to the muscles and cognitive processing, and gait abnormalities. The maximum oxygen uptake during exercise is approximately one half of sedentary controls. Most importantly, ME/CFS patients usually have an elevated resting heart rate, a reduced heart rate during exercise, and can not achieve age-predicted target heart rates. As these abnormalities can be due to a sub-optimal level of heart functioning and/or autonomic disturbances, not only is it inappropriate for ME/CFS patients to undergo a treadmill stress test or be pushed toward age-predicted target heart rates, but this is potentially DANGEROUS.
The Cardiolite Stress Test
The pharmacological or Cardiolite stress test provides the doctor with an alternative method to assess the hearts ability to work under stress for the individual who cannot perform a treadmill test. This two-stage study allows the physician to see pictures of the heart when it is first at rest, and second, following stress. An intravenous line (IV) is placed in the arm before the first injection of pharmaceuticals. During the resting study, a small amount of radioactive material or tracer (Cardiolite) is injected to create pictures of the heart at rest. In the stress study, Persantine is administered to induce stress, and then another injection of Cardiolite is given to take pictures of the heart under stress.
Cardiolite, the radioactive tracer, decays in order to reach a more stable state and in doing so emits energy in the form of gamma rays. This tracer temporarily marks the red blood cells, which allows the doctor to document blood flow to you heart muscles. The level of radioactivity used is extremely low and has no side effects. In fact, the amount of radioactivity received is about the same amount a person is exposed to in 1 to 2 years from natural (background) radiation present in the environment.
A special camera (gamma scintillation camera), which detects the gamma rays emitted from the radioactive tracer, is installed in a piece of equipment similar to a CAT or MRI scan. The individual is placed inside the cylinder of the scanning device and the camera takes pictures of the heart at various angles. These pictures will show the amount of the radioactive tracer that reaches the heart muscle. As the tracer moves through the heart muscle, areas that have good blood flow absorb the tracer. If an area of heart muscle does not adequately absorb the tracer, it means either that blood flow is severely reduced (ischemia) and/or there has been a previous heart attack. The tracer is eliminated by the body, usually in the urine or stool in less than 24 hours.
Preparation for the Stress Test
Before a pharmacological (medication) stress test:
* Talk with your doctor regarding things you must do to prepare for the test and any other concerns or questions you may have;
* Absolutely no foods, drinks or drugs containing caffeine can be taken for 24 hours prior to the test in order to avoid (1) stomach upset and (2) major redirection of blood flow toward the digestive tract during the procedure
* Patients may or may not be able to take heart and blood pressure medications, depending on whether or not they interfere with the accuracy and effectiveness of the test
* Wear unrestricting clothes so that you will be more comfortable during the procedure; and
* Prior to the test you may be asked to sign a consent form. Read it carefully and question the doctor or technician supervising the test regarding any concerns you may have.
Important Info to Provide Physician
For women, it is important to notify your supervising physician regarding:
* pregnancy, and nursing. The scan is contraindicated in these cases.
* presence of breast implants. These can obscure the pictures.
* advise the supervising physician that you have ME/CFS.
The Resting Study
Following the first injection of Cardiolite, the patient is placed under the special camera in the scanning device. Pictures are taken and information is relayed to a computer that generates a corresponding image. The camera, which does not produce any radiation, is placed close to the chest, and pictures are taken for approximately 30 40 minutes. During that time it is important for the patient to remain very still while the pictures are being taken. Following the study, EKG electrodes are placed on the chest to constantly monitor the heart during the stress test.
The Stress Study
Instead of using treadmill exercise, the heart is stressed with the use of medication (Perdantine), which causes the healthy coronary arteries (but not the blocked ones) to dilate or get wider thus increasing the blood flow to the heart. During the test, the patient is constantly monitored by a nurse or physician. The preparation takes up to 30 minutes, but the actual stress portion of the test takes about 10 to15 minutes. Before the end of the stress test, a second injection (Cardiolite) is administered. This radiopharmaceutical is taken up by the heart muscle and can be visualized by the camera in the same manner as the rest study. The imaging portion of the stress study takes approximately 45 minutes.
Common Responses Experienced During Studies
Normal responses during testing include feeling tired, shortness of breath, sweating and discomfort in the chest, arm or jaw. Severe shortness of breath, extreme tiredness, dizziness, lightheadedness, leg cramps or soreness should be reported to the technologist immediately. The supervising practitioner will alter or stop the test early if it is unsafe to continue.
After the Stress Test
When the test is over, patients may eat or drink and return to their normal routine. They may resume all medications.
Data Comparison
The images and other data of the resting stage study are compared with those of the stress study to give the doctor the information needed to evaluate how you heart is functioning. Your doctor will provide you with feedback.
Summary
The pharmacological stress test provides more precise information on heart function that a treadmill stress test, such as:
* its images provide valuable information as to why you may be experiencing chest pain or angina;
* if you have recently had a heart attack, it can assist the doctor in determining the damage sustained by the heart during the attack;
* if you are about to experience surgery, it can help the physician assess whether the heart is strong enough to withstand a long or complicated operation; and
* the images reliably identifies Coronary Artery Disease in women, which is advantageous if diagnosed early, as it provides the opportunity for effective early treatment.
If you require a stress test, it may be of assistance to provide your doctor with the article, ME/CFS Post-Exertional Malaise/Fatigue and Exercise as well as this one.
