Introduction
A nuclear stress test is an imaging test that is done to diagnose and monitor heart problems such as coronary artery disease. The healthcare provider injects a small amount of radioactive substance into the bloodstream, and a picture of the blood flow in and around is taken with the help of a special camera. There are two phrases for the test: during rest and after exercise. This test usually takes 3 to 4 hours, and although a small amount of radiation is exposed to the person, this test is considered safe by medical experts. The test may also be called cardiac positron emission tomography (PET), cardiac single-photon emission tomography (SPECT), and myocardial perfusion imaging (MPI).
What Is Nuclear Stress Test?
The nuclear stress test is an imaging test that is done to view the blood flow to the heart at rest and during exercise and help diagnose heart disease. A small amount of radioactive substance is injected by the healthcare provider, known as a tracer or radiopharmaceutical, into the bloodstream. The tracer is absorbed by the blood vessels and heart muscle, making them more visible in images. A specific camera is used by the provider which is used to take pictures of blood flow in and around the heart.
What Does the Nuclear Stress Test Show?
Nuclear stress test is used to diagnose and monitor coronary artery disease, showing blood flow to the heart. When there is blockage of blood vessels or clogged, coronary artery disease occurs. The test is also used to determine whether the heart's pumping is proper, whether poor blood flow can be identified, and whether the heart is damaged and blocked arteries are located. This test is also used in individuals with bundle branch block, congestive heart failure, acute coronary syndrome, and other confirmed or suspected heart problems.
What Are the Benefits of a Nuclear Stress Test?
The benefits to nuclear stress test are it helps doctors to diagnose certain heart conditions by providing important information about an individual’s heart, such as if there is narrowing or blockage, damage from any previous heart attacks, the best course of treatment is determined for a person’s chest discomfort and previous heart procedures can be checked whether blood flow has improved.
Additional benefits of nuclear tests are that they help in the early diagnosis of coronary artery disease in individuals at risk of heart attack, help to assess an individual's risk of developing coronary artery disease, and have better accuracy than treadmill testing, exercise or ECG stress test.
How Is a Nuclear Stress Test Done with Exercise and Without Exercise?
In nuclear stress tests with exercise, the tracer is injected by the doctor into veins in an individual's arm. The tracer is absorbed, and the gamma camera takes a picture of the heart. Individuals will be in a lying position while the medical professionals are performing the test. The doctor injects another tracer dose when the individual’s heart works hard while moving on a treadmill or stationary bicycle. The exercise can be resumed once absorbed. The photos of the person’s heart are taken with a gamma camera.
When the individual cannot do physical exercise due to mobility issues or conditions such as arthritis, chemical or pharmacological stress tests are performed. For individuals who are undergoing chemical stress tests, medical professionals will inject medication such as adenosine, dobutamine, and dipyridamole. This medication will help to increase an individual's heart rate by mimicking the effects of exercise.
What Happens during a Nuclear Stress Test?
Individuals are asked to lie down on the examination table, and an IV line is inserted into the vein in the arm by the healthcare professional, and a tracer will flow into the IV line and the bloodstream. The tracer will be absorbed after 15-40 minutes by the person’s heart, and then the person's blood is picked up by a gamma camera when they are resting. Electrodes are flat metal disks the healthcare provider applies to a person’s arm, legs, and chest. The electrodes are then connected to an Electrocardiogram (ECG), and ECG will monitor an individual's heart rate and will also let the gamma camera know when to take a picture. More tracer is then injected by the healthcare provider when the individual’s heart is working at its peak activity level and is then asked to wait for 15 to 40 minutes for the tracer to absorb. The exercise can be restarted, and a gamma camera will take more pictures of an individual's blood flow.
What Happens After a Nuclear Stress Test?
After a nuclear stress test, the individual is monitored for 10-15 minutes by the healthcare provider. The injected tracer will pass through the individual's body and into their urine; to remove it faster, the individual can drink plenty of water. If the blood flow is typical of an individual during both rest and exercise portions of the test, the result is the heart is functioning as expected. If the result shows reduced blood flow to the individual heart, it could be due to coronary artery disease, scarring from a previous heart attack, or poor physical health. During nuclear stress tests, individuals should avoid bringing babies or young children for the rest of the day as they can have residual radiation due to the test.
What Are the Side Effects of a Nuclear Stress Test?
Headache and feeling flushed are the most common side effects of a nuclear stress test, and other possible side effects are nausea, dizziness, and chest pain. Sometimes, the individual might be allergic to the tracer used during the test. There is a rare risk of heart attack and sudden death due to two drugs used in this test, Lexicon, and Adenoscan, and the healthcare provider uses these drugs to stimulate exercise in individuals who are not able to do physical exercise.
There is an increase in blood flow with the use of these drugs, which helps to identify the blockages. Sometimes, there can be more blood flow to unobstructed areas that will leave problem areas without blood. Therefore, these drugs should be avoided by healthcare professionals in individuals with unstable angina or any other cardiac instability.
Conclusion
A nuclear stress test helps to detect certain heart conditions, and this test is considered generally safe. This test is not advised for pregnant women and individuals with heart attack risk.
