Nuclear Cardiology and Stress Testing

About Stress Testing

A stress test is used to help your doctor determine how your heart handles a greater workload or increased physiological stress. This is induced through exercise or by giving you a medication that mimics the effects of exercise. By increasing the workload of your heart, we can detect decreased or compromised blood flow in the arteries that supply blood to your heart. If decreased blood flow during stress is detected it can indicate a blockage in one or more of your coronary arteries.

How to prepare for your test:

• First schedule your appointment on a day where you can dedicate 3-4 hours of your time.
• Discuss medications with your doctor before your stress test is scheduled to determine whether any of your medications including over the counter medications and vitamins need to be stopped.
• Do not eat food or drink caffeinated drinks 6 hours before your stress test. If you are diabetic, you may eat a light meal 3 hours before.
• Wear comfortable clothing and walking shoes.
• Avoid wearing an underwire bra or metal buttons.

Pre-caution: If you are breast feeding, are pregnant or think you may be pregnant please tell your doctor.

Exercise Tolerance Test

Also known as Treadmill Stress Test

This test involves walking on a treadmill for approximately 10-15 minutes or until target heart rate is reached while we monitor your heart rhythm and blood pressure for changes.

Exercise Myocardial Perfusion Test

Also known as a Exercise Nuclear Stress Test

This test is similar to the treadmill test stated above with the addition of a radioactive tracer. A small intravenous catheter is placed in your arm to inject a radioactive material that travels to the arteries of your heart.  Soon afterwards you will like down under a gamma camera for about 20 minutes to take pictures of your heart while resting.  These images are repeated after walking on a treadmill for several minutes. Your heart doctor will compare the before and after pictures to assess for areas of decreased blood flow. This test can take 3-4 hours to complete in a single day or you may have the option to complete it in two days. The radiation exposure during this test is considered acceptable and safe.

Pharmacologic Myocardial Perfusion Test

Also known as a Pharmacologic Nuclear Stress Test

This test is exactly like the one stated above except it uses an IV medication called Regadenoson (Lexi scan). This medication is administered over 30 seconds and can cause symptoms such as flushing, chest tightness and headache. This medication mimics the stress of exercise without actually physically moving. This test is reserved for those with mobility issues that cannot tolerate physical exercise.

Nuclear stress test

A nuclear stress test uses radioactive dye and an imaging machine to create pictures showing the blood flow to your heart. The test measures blood flow while you are at rest and are exerting yourself, showing areas with poor blood flow or damage in your heart.

The test usually involves injecting radioactive dye, then taking two sets of images of your heart — one while you’re at rest and another after exertion.

Risks

A nuclear stress test is generally safe, and complications are rare. As with any medical procedure, there is a risk of complications, including:

• Allergic reaction. Though rare, you could be allergic to the radioactive dye that’s injected during a nuclear stress test.
• Abnormal heart rhythms (arrhythmias). Arrhythmias brought on during a stress test usually go away shortly after you stop exercising or the medication wears off. Life-threatening arrhythmias are rare.
• Heart attack (myocardial infarction). Although extremely rare, it’s possible that a nuclear stress test could cause a heart attack.
• Dizziness or chest pain. These symptoms can occur during a stress test. Other possible signs and symptoms include nausea, shakiness, headache, flushing, shortness of breath and anxiety. These signs and symptoms are usually mild and brief, but tell your doctor if they occur.
• Low blood pressure. Blood pressure may drop during or immediately after exercise, possibly causing you to feel dizzy or faint. The problem should go away after you stop exercising.

Before a nuclear stress test

First, your doctor will ask you some questions about your medical history and how often and strenuously you exercise. This helps determine the amount of exercise that’s appropriate for you during the test. Your doctor will also listen to your heart and lungs for any abnormalities that might affect your test results.

During nuclear stress test

Before you start the test, a technician inserts an intravenous (IV) line into your arm and injects a radioactive dye (radiopharmaceutical or radiotracer).

The radiotracer may feel cold when it’s first injected into your arm. It takes about 20 to 40 minutes for your heart cells to absorb the radiotracer.

A nurse or technician will place sticky patches (electrodes) on your chest, legs and arms. Some areas may need to be shaved to help them stick. The electrodes have wires connected to an electrocardiogram machine, which records the electrical signals that trigger your heartbeats. A cuff on your arm checks your blood pressure during the test. You may be asked to breathe into a tube during the test to show how well you’re able to breathe during exercise.

For an exercise stress test, you’ll probably walk on a treadmill or ride a stationary bike. You’ll start slowly, and the exercise gets more difficult as the test progresses. You can use the railing on the treadmill for balance. Don’t hang on tightly, as this may skew the results.

You’ll continue exercising until either your heart rate has reached a set target, you develop symptoms that don’t allow you to continue or you develop:

• Moderate to severe chest pain.
• Severe shortness of breath.
• Abnormally high or low blood pressure.
• An abnormal heart rhythm.
• Dizziness.
• Certain changes in your electrocardiogram.

After a nuclear stress test

After you stop exercising, you might be asked to stand still for several seconds and then lie down for a period of time with the monitors in place. Your doctor can watch for any abnormalities as your heart rate and breathing return to normal.