Cardiac stress testing is a non-invasive procedure that tests for problems with the heart's blood supply. One type of stress test is the exercise treadmill test (ETT). In this test, the patient walks on a treadmill while connected to an ECG monitor. The cardiologist looks for changes in the ECG during exercise, which could possibly indicate an abnormality with the heart's blood supply.
Another type of stress test is stress echocardiography. This test involves obtaining ultrasound images of the heart before and after the patient exercises on a treadmill. These images show the ability of the heart to increase its pumping action during exercise. Patients who are unable to exercise on a treadmill can be given a medication called dobutamine, which will increase the heart rate and contractility (dobutamine stress echocardiography). The advantages of stress echocardiography are:
- The ability to obtain an echocardiogram detecting ischemic wall motion abnormalities immediately after exercise testing.
- No reperfusion necessary.
- No radiation required.
- Results available for cardiologist to view immediately after the exam.
Nuclear cardiology obtains information about the heart's blood supply through the use of a small amount of radioactive tracer material. Myocardial perfusion imaging studies involve the use of tracer materials called thallium, Sestamibi (Cardiolite), or a combination of the two (dual isotopes). The specific isotope used is determined by a set of criteria, which includes the patient's height and weight. The radioactive isotopes used for the studies produce less radiation than most x-ray procedures.
If a patient is unable to walk on the treadmill, a stress agent, otherwise known as a pharmacologic stress medication, will be injected through a small intravenous catheter placed in an arm vein. The injected medication provides the "heart stress" needed in place of the exercise to achieve test results. 40-50% of our patients are tested using a pharmacologic agent.
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