could not complete nuclear stress test, could not reach target heart rate on treadmill, what could that mean

Dear Anon, I am sure this was a pretty frightening experience for you. All the uncertainty can also increase your stress levels. May I ask you your age? Weight? History of heart problems? Here is what I know about nuclear stress tests. A nuclear stress test usually refers to stress testing (i.e. EKG) that is performed in combination with a nuclear imaging test, such as SPECT scan or a PET scan. In either case, the test can reveal more detailed information than a conventional exercise EKG test.

In general, a nuclear stress test is more accurate and provides more information than a standard exercise EKG. Your doctor may have evaluated your condition and has decided that a nuclear stress test may provide a better diagnostic result that the most common EKG. However, these tests do have drawbacks. They are more expensive and require more time, and there is exposure to a small amount of radioactive substances.

A nuclear stress test can help measure:

1. Extent of artery blockage
2. Prognosis of patients who have recently suffered a heart attack (myocardial infarction)
3. Effectiveness of cardiac procedures previously performed, such as coronary stenting (in which a wire mesh metal tube is inserted into an artery to keep it open), or balloon angioplasty (in which a balloon-tipped catheter is used to push plaque back against artery walls, improving blood flow)
4. Cause(s) of chest pain
5. Level of exercise that a patient can safely perform

In every case patients are advised to refrain from eating or drinking for about four to six hours before the test. An empty stomach will help evaluate the heart’s performance more effectively as it will prevent cramping during exertion. Patients are also advised to refrain from taking caffeine and certain medications in the days or hours leading up to the test. You probably were told all of this, in addition you were advised of possible minor discomfort when injected with the radionuclide substance.

I was wondering if before the nuclear component of the nuclear stress test you performed the standard stress test (EKG. If so, the next step would probably have been the stress test (which involves physical exertion) or a pharmacological stress test (which involves a medication that mimics the effects of exertion on the heart).

Regardless of how the heart rate is elevated, you would have obtained pictures after stress has been placed on the heart through either exercise (usually on a treadmill) or medication. Once the desired heart rate has been reached, the thallium (or technetium or sestamibi) is injected.

Based on your posting, it appears that you only got to the stress test phase where they put you on a treadmill. If you were not able to complete this portion, there are many possible causes which your doctor will be able to provide to you. But I think you are going to need to complete the nuclear test to identify the root cause of your symptoms.

Studies have shown that the period of time between the exercise test (treadmill) and the imaging will affect the test results. Some studies have shown that the best results are obtained when three image sets are taken: during stress, during the post-stress redistribution period, and after reinjection. By comparing the three sets of images, physicians can tell which parts of the heart muscle absorbed the isotope and how deeply it penetrated. So I suggest you go through with all the testing and work with your physician to make sure you get to the bottom of the problem.