Will Happen After a Cardiac Stress Test?
It seems that no other nuclear medicine exam has more variation than a cardiac stress test. There are, at present, two commonly used radiotracers – the time-honored thallium and the newer technetium MIBI. Either of these can be combined with either standard “planar” imaging or with the newer cross-sectional imagine (“SPECT”), in which the nuclear camera rotates around the patient’s chest. To complicate matters further, a patient can either undergo “real” exercise by walking on a treadmill or else receive an intravenous injection of dipyrdamole which dilates the arteries in the heart just as exercise would.
Fortunately, some things are less variable. You will have standard EKG leads attached to your chest just as for an electrocardiogram. An intravenous line will be started in your arm. There will be two sets of images (at least!). One will be immediately after “stress,” whether due to real exercise or simulated by dipyrdamle. The other will be at “rest.”
will Happen in a Nuclear Cardiac Stress Test? Part II
(Only for the VERY interested!)
If you are able to exercise, you will be shown how to walk on a treadmill. At first the treadmill moves slowly and you may not have any problem “keeping up.” Then, as the test progresses, you will find yourself having to walk faster and faster. Your blood pressure, heart rate and electrocardiogram will be monitored as you exercise. The longer you can exercise, the better the test. However, if you have chest pain or feel dizzy, you MUST inform the physician monitoring the examination. When you feel you can exercise no longer, radiotracer will be injected through the I.V. line, and you will be helped onto a table where images of your heart will be taken by the nuclear medicine camera (stress images).
If you are NOT able to exercise, you will be given dipyrdamole slowly through your I.V. line followed by radiotracer. This simulates exercise. Pseudo “stress” images of the heart are taken as above.
In either case, you will be asked to return in about 3 to 4 hours for repeat images (called variously delayed, rest or redistribution images). Re-injection of additional radiotracer may be made depending on the radiotracer and the imagine protocol.
Long Will The Test Take?
The exercise, and the preparation for it, can take 20 to 40 minutes or more depending on how much exercise you can tolerate. Imaging of your heart can take 30 minutes or more and there is a gap of 3 hours or so between sets of images.
All told, Nuclear Cardiac Stress Testing takes the better part of a day.
What Is The Nuclear Physician Looking For?
The nuclear physician is looking for areas of the heart that have decreased blood flow during exercise (or its equivalent) but normal flow during rest.
This decreased flow during physical stress, which is often associated with chest pain, is presumed due to narrowing or partial blockage of one or more (coronary) arteries in the heart. The hope is, that with medication or with surgery, blood flow can be increased, thereby relieving chest pain and improving exercise tolerance.
Other Test Be Needed?
Depending on the results of your nuclear cardiac stress test AND your physical and clinical condition, coronary angiography and perhaps coronary artery dilation (angioplasty) may be performed.
Sometimes coronary artery bypass surgery is considered. In other situations, medical management seems more appropriate.
These alternatives should be discussed with your doctor when you get the results of your nuclear cardiac stress test.
Preparation Is Suggested?
Because there are so many different ways of going about nuclear cardiac stress testing, the best suggestion regarding eating is that you should contact the nuclear medicine department where you test will be done for their recommendations. Diabetic patients on insulin merit special consideration, and the nuclear medicine department should know about this important information so that meals can be scheduled appropriately.
Because various drugs can influence the stress test, you are encouraged to speak with your doctor to find out what cardiac medications you should be taking at the time of your examination.
If you will
be performing treadmill exercise, you would be advised to wear comfortable
clothes including walking shoes or sneakers.
A detailed note from your doctor which includes your current medication is very important.
Words For a Nuclear Cardiac Stress Test
Nuclear cardiac stress testing may seem complicated from the “WHAT WILL HAPPEN?” section above. In practice, it is not complicated because a patient will simply follow whatever protocol (plan) is being used by the nuclear medicine department where the study is being done. All approaches can yield excellent results if necessary care is taken.