What is nuclear heart testing? — Nuclear heart testing is a way for doctors to check how healthy your heart is. A nuclear heart test is an imaging test that can show:

  • How much blood flows to your heart muscle
  • How well your heart pumps blood to the rest of your body

Usually, people have a test called a “stress test” along with a nuclear heart test. A stress test measures how well the heart works when it is pumping very fast. When the heart pumps fast, it needs more blood. A stress test shows if the heart gets enough blood during these times. When a stress test is done with a nuclear heart test, it’s called a “nuclear stress test.”

Why might my doctor order a nuclear heart test? — Your doctor might order a nuclear heart test or a nuclear stress test to:

  • Check if your heart muscle is getting enough blood
  • Look for certain heart conditions or follow a known heart condition
  • Check your heart after a heart attack or heart surgery
  • See how well your heart pumps blood to the rest of your body

How do I prepare for a nuclear heart test? — Before you have a nuclear heart test, your doctor will ask about all of the medicines you take. He or she might have you stop or change some of your medicines before the test. He or she will tell you when to stop eating and drinking before your test. Your doctor also might ask you not to drink anything that has caffeine in it for 24 hours beforehand.

What happens during a nuclear heart test? — First, the doctor, nurse, or technician will do a test called an “ECG.” An ECG records your heart rate and rhythm by measuring the electrical activity in your heart (figure 1).

Then, the doctor, nurse, or technician will have you lie down on a table. He or she will put an IV (needle) in your arm and put a radioactive substance, called a “tracer,” into the IV. The tracer will travel through the blood to your heart. A camera outside your body will follow the tracer’s signals. The camera will take pictures and create images that show the blood flowing to and through your heart.

If you have a nuclear stress test, you will have 1 set of pictures done while you rest and 1 set done when your heart is pumping fast. To “stress” your heart and raise your heart rate, the doctor will do 1 of the following:

  • Have you run or walk on a treadmill (figure 2)
  • Have you pedal a stationary bike (a bike that doesn’t move, except for the pedals)
  • Give you medicine to make your heart pump faster – People who can’t exercise can get medicine instead.

After the stress test, the doctor will take another set of pictures. That way, he or she can compare the results from the 2 different times.

What are the downsides of nuclear heart tests? — Nuclear heart tests do involve a small amount of radiation. Too much radiation can cause serious health problems, like cancer. The amount of radiation in nuclear tests will not cause any long-term problems in most people. But your doctor will talk with you about the possible long-term side effects of radiation.

Other downsides of nuclear heart tests can include:

  • Pain or redness where the IV was in the arm
  • Side effects from the stress test – When people exercise and their heart pumps very fast, they can get symptoms such as chest pain, trouble breathing, an abnormal heartbeat, or feeling dizzy or faint.

What if I am pregnant? — If you are pregnant, let your doctor know. He or she might postpone the nuclear heart test until after your baby is born.