The most common nuclear cardiology procedure is the Gated SPECT (Single Photon Emission Computerized Tomography) Myocardial Perfusion Stress Test. This test uses a standard treadmill stress test to increase a patient's heart rate to a certain level, which is determined by age and gender. At the moment this heart rate is reached, a small dose of radioactive medication (radioisotope) is injected intravenously. The radioisotope travels through the blood stream to the heart, where it is taken up by the heart muscle (mycardium) in a pattern reflective of the blood flow to the muscle. This information is gathered by gamma camera imaging. The second portion of the test, called the rest study, uses the same radioisotope but is injected while the patient is at rest. Images by the gamma camera are again acquired, and a computer analysis of both the stress and rest acquisitions is examined by the nuclear cardiologist.

Nuclear cardiology services may include testing without exercise. A Persantine (dipyridamole) perfusion study uses medication instead of a treadmill to prepare the heart for radioactive imaging. Patients with pacemakers, or certain types of electrocardiogram patterns are likely to have a Persantine stress test, as well as those who cannot reach their target heart rate due to lung or musculoskeletal problems. Preoperative clearance for certain vascular surgeries many times include Persantine studies.

Another rest study, a MUGA (multiunit-gated acquisition) scan, measures the efficiency of the heart's pumping or output. A radioisotope is injected at rest, and imaging is performed while a simplified cardiac monitor called a "gate" records the patient's heart beats. The physician then interprets the final computer analysis to assess how well the heart is functioning.

We often see individuals who undergo a standard stress test to determine if they are fit for exercise, or ready for planned surgery or other events that may be stressful to the heart. When these test results are questionable, a nuclear cardiology study can often provide the information needed to reassure the patient of the absence of significant underlying heart disease. The radioisotopes that are used for nuclear diagnostic testing do expose the patient to radiation, but the maximum dose to any part of the body is less than the exposure from a routine back X-ray.

For further information about nuclear cardiology or stress testing, please write to Dr. Drout
or email atinfo@rmadoctors.com.