Oftentimes, additional information provided by nuclear imaging can be helpful in giving more accurate information about any blockages in the blood supply to the heart. A nuclear stress testing (either done with a chemical or combined with exercise stress test) can be performed to provide that information.
The nuclear stress test can be performed in a number of different protocols. In a typical protocol, you would be given a nuclear tracer during rest. The tracer goes to the heat muscle cells and can be visualized with a special cameral. For the stress portion, if an exercise protocol is used, you will walk/jog on the treadmill and the nuclear tracer is again given at peak exercises. The “stress” image is then compared to the “rest” image and differences in the images can give information about any blood flow issues. If you are unable to walk/run on a treadmill, then a chemical may be used to simulate stress. Typically, this is done with lexiscan or dipyridamole. After lexiscan is given, the tracer would be given approximately 1 minutes later and then the stress image obtained.
Stat! Cardiologist is able to perform a number of these tests to provide an accurate picture of your heart. Results are usually available same day. If the imaging detects any issues, further plan of care will be discussed and a strategy developed (with your input) regarding how to best manage. Oftentimes, stable symptoms can be managed with medications alone. However, for symptoms that are progressing or uncontrolled with medications, it may require intervention (such as balloon angioplasty or coronary stent).
In addition to stress testing, nuclear tracers can be utilized to do viability testing. Viability testing allows us to see if a part of the heart muscle is still alive and whether an intervention is worthwhile. This utilizes a different protocol and different tracers (such as Thallium or FDG utilizing PET). Nuclear tracers can be used to do even other studies such as a MUGA scan which is used to evaluate heart function. However, this can also be done with echocardiography.
The amount of radiation involved in nuclear stress testing is actually quite low. The amount of tracer used is recorded by their radiation. For a typical stress test which will utilize technetium 99m sestamibi, a typical rest dose may be 6 grey. Typical Stress dose may be 15 grey.
Things to do before stress test:
-Avoid drinking any coffee or any drink that would have caffeine as that may invalidate the test. You must avoid such drinks for at least 12 hrs prior to the test.
-If you have asthma or COPD, bring your inhaler with you. The chemical stress test may often cause shortness of breath.
-Wear comfortable clothes.