Stress Myocardial Perfusion Imaging

Purpose

Stress myocardial perfusion imaging is a nuclear cardiology test that shows how well blood flows to the muscle of the heart (the myocardium). A radioactive tracer injected into the patient’s bloodstream lets doctors view heart function using a scanner called a SPECT camera. SPECT stands for single photon emission computed tomography.

Two sets of images are taken, one with the patient at rest and one with the patient at stress, when the heart is working hardest. There are two types of stress tests:

• Exercise on a treadmill is the standard way to stress the heart.
• Drug-induced stress is used when a patient is unable to perform the exercise test due to a physical disability or other reason. The patient is given a drug which increases blood flow to the heart as exercising would.

The patient’s doctor will determine which of the stress tests is appropriate. Either test takes three to four hours to complete.

Description

1. A nuclear medicine technologist discusses the test with the patient. The patient is asked to sign a Nuclear Cardiology Registry Consent Form, which allows the department to keep an electronic record of the test in a secure database.
2. The patient receives an injection into the vein of one arm. The injection contains a small amount of radioactive material that will travel to the heart muscle.
3. Approximately 45 minutes later, the patient is asked to lie back, with both arms positioned overhead, and to remain still. A camera then takes a series of pictures. This process takes about 15 minutes.
4. After these pictures are completed, electrocardiogram leads are placed on the patient’s chest to monitor the heart rhythm, and an intravenous line is inserted in the vein of one arm.
5. A stress technologist discusses the stress portion of the test with the patient. The patient is asked to sign a Stress Test Consent Form. The patient should read it carefully and should not hesitate to ask any questions of the technologist or supervising doctor. It is important that the patient understand the entire procedure before it begins.
6. The patient then undergoes the exercise or chemical stress test as requested by the doctor. The technologist assesses the patient’s maximum level of exercise and administers a second injection of radioactive tracer. It is important for the patient to let the staff know if he or she experiences any discomfort or other symptoms during the test to allow the staff to better assess when to end the test. Also, the patient should inform staff if he or she experiences any shortness of breath, chest pain, arm pain, palpitations, difficulty walking, fatigue, headache, or other discomfort after the test.
7. When the stress test is completed, the patient has 30 to 45 minutes to eat a light meal prior to the second set of pictures. This set of pictures will again take approximately 15 minutes.
8. The nuclear technologist processes the study. A doctor experienced in the interpretation of the studies reads the test, and a report is sent to the patient’s doctor.

Patient Instructions

Prior to taking the test, patients should download, print, and read the University of Ottawa Heart Institute’s detailed diet and medication instructions (pdf).

The patient should wear loose-fitting clothing to the test, and if exercising, bring comfortable shoes as well as shorts or sweat pants.