What is pharmacologic stress testing?
Pharmacologic stress testing is a method of testing the functioning capacity of the heart by administering certain medications (pharmacologic agents). These medications mimic the response of the heart to physical stress (exercise). You may get a pharmacologic stress test done if you are unable to exercise (e.g., walk or run on a treadmill). During the test, drugs such as adenosine, dobutamine, regadenoson or dipyridamole make the heart respond as if you are exercising.
These medications may increase your heart rate and the strength of contractions (pumping) of the heart muscles. This causes an increase in the blood flow and may cause the blood vessels supplying blood to the heart (coronary arteries) to widen so that there will be more blood flow to the heart. Through this test, the doctor can learn how your heart responds to stress, but without making you ramp up your heart rate through exercise. Pharmacologic stress testing is used in combination with other tests such as electrocardiography (ECG) and radionuclide imaging for gauging heart health.
What is pharmacologic stress testing used for?
You may require pharmacologic stress testing if you cannot exercise but have symptoms related to heart disease. According to the American College of Cardiology Foundation (ACCF), pharmacologic stress testing is generally performed in the following cases:
- Elderly patients with decreased functional capacity and possible coronary artery disease (CAD) (a medical condition in which the blood flow through the coronary arteries is compromised)
- Patients with poor general health and possible CAD
- Younger patients with functional impairment due to injury, arthritis, orthopedic problems, peripheral neuropathy or peripheral vascular disease, in which a maximal heart rate is not easily achieved with routine exercise stress testing, usually because of early onset of fatigue due to muscle, bone, neurologic or vascular problems rather than cardiac ischemia (decreased blood flow to the heart)
- Patients taking beta-blockers or other medications that slow the heart rate and prevent an adequate heart response to exercise
Your doctor may use the test to:
How is pharmacologic stress testing performed?
The test is performed as an outpatient procedure, which means you may go back home the same day unless you are admitted for some health conditions.
Before the test
Your doctor may
- Ask you to not eat or drink anything other than water and refrain from smoking for three hours before the test.
- Ask you to not consume anything with caffeine, including products that say “decaffeinated” or “caffeine-free,” after midnight, the night before the test.
- Ask you to wear comfortable clothing.
- Ask you to bring a list of all current medications, along with times and dosages.
- Ask you to withdraw medications that will interfere with the results if possible, for 24 hours before the test.
- Ask you to avoid strenuous activities (jogging, running) before the appointment.
- Explain the procedure along with the risks involved.
- Ask you to shave your chest.
During the test
- Anesthesia is not used in pharmacologic stress testing.
- Some centers prefer to use pharmacologic stress testing along with echocardiogram, magnetic resonance imaging (MRI) and computed tomography (CT) scanning.
- Blood pressure, heart rate and electrocardiography (ECG) are monitored before, during and after the test. Imaging is obtained at specified times.
- An intravenous (IV) line is placed in a vein of your arm.
- A small amount of radioactive tracer is given through the IV line. The tracer releases radiation detected by a special “gamma camera,” to produce computer images of the heart.
- The healthcare provider will place electrodes (sticky patches) on your chest. The electrodes are attached to wires that send the electrical activity of your heart to the ECG monitor.
- A baseline ECG will be performed before giving the medication.
- Your healthcare provider will administer the medicine slowly through the IV line.
- They will record many ECGs during and after the medicine is administered.
- The doctor may continue monitoring for at least four minutes after the effects of the pharmacologic stress testing agent have resolved.