Nuclear stress test: what is it done for?

The nuclear stress test is one of the radiology studies that are used to assess the condition of the heart. Specifically, it allows you to see the blood flow of this organ. It is done at different times, both at rest and during exercise.

It can help diagnose problems with the coronary arteries, which are those that supply the heart. In addition, it serves to guide certain treatments. Therefore, in this article we explain what it consists of and everything you need to know about the nuclear stress test.

What is the nuclear stress test?

The nuclear stress test is a technique that has been developed recently. Allows you to observe the blood flow of the heart to check for any areas that are not getting enough blood or are damaged.

This is done by measuring the flow at rest and during exercise. This is done by injecting a radioactive dye through a vein, ingested or even inhaled. This substance accumulates in the organs and emits gamma ray energy.

According to the specialists of RadiologyInfoBy means of special devices, images can be taken that allow us to observe the structure and function of the heart. The most widely used are single photon emission computed tomography (SPECT) and the gamma camera.

Multiple images are obtained. First during rest and then during effort. This way, it can be seen if the arteries of the heart are able to cope with the increased oxygen demand that occurs with exercise.

The nuclear stress test is performed in a controlled environment. Stationary bicycles or treadmills are often used to generate this effort. It is a technique that, in addition to serving to diagnose, helps to better choose the treatment.

The nuclear stress test can be ordered to evaluate a suspected disease state or to determine a treatment in already certified pathologies of the heart.

What is it done for?

According to specialists from the Mayo Clinic, one of the main purposes of the nuclear stress test is diagnose coronary artery disease. They are the blood vessels that are responsible for carrying oxygenated blood to the heart.

These arteries are prone to damage as a result of atherosclerosis. This is a pathology that consists of the accumulation of cholesterol plaques and other substances on the arterial walls. These deposits prevent blood flow from passing normally.

When we exert ourselves, the heart needs to pump blood faster and harder to reach all organs and tissues. In turn, the coronary arteries must also supply more blood to the heart in order for it to function properly.

Because of this, the arteries contract. If there is a plaque inside, it is possible that with the vasoconstriction the blood flow is interrupted. This is evidenced by a nuclear stress test.

It can also serve to see if, once the disease is diagnosed and treatment is in place, it works effectively. The usual approach is usually based on medications that help to dilate the blood vessels, such as nitroglycerin.

In this way, nuclear stress testing is often recommended for people with angina pectoris. That is, when there is chest pain similar to that of a heart attack that appears in the face of efforts or stress situations. It may also be indicated if there is an altered electrocardiogram.

You may be interested in: Angina pectoris: symptoms, causes and prevention

How to prepare for the exam

Since what is desired is to observe the cardiac function, it may be necessary to avoid certain substances and medications before going. As the specialists of Florida Cardiology, it is important not to ingest caffeine or smoke before the test.

The doctor should be aware of any treatment that is being taken before. For example, certain inhalers that are used for respiratory conditions can alter the result. Therefore, it may be indicated to remove them before the nuclear stress test.

Similarly, as we have already pointed out, exercise is required during the procedure. Hence the ideal is go with sports and comfortable clothes. Electrodes are used that are glued to the skin, so no type of cream or lotion should be applied either.

You might be interested: Recommended foods for cardiovascular health

How is the nuclear stress test performed?

The nuclear stress test usually takes hours. This is because you have to administer the radioactive drug and wait for it to be absorbed by the different tissues. Once 40 minutes have passed, images of the heart function at rest begin to be obtained. In order to get a complete picture, an electrocardiogram is also performed.

When the images have been taken at rest, the effort itself is carried out. Most often, an exercise bike or treadmill is used. Little by little the intensity of the exercise is increased and it reaches a point where the heart rate is very high or symptoms begin to appear.

At this point, the radioactive drug is injected again. Images of the heart are taken again to see if any areas are not getting enough blood flow. As the dye is distributed with the blood, the least stained areas will be those that have a circulation problem.

If at any time during the test the patient begins to feel very bad, it is stopped. It is common that, if there is a problem in the arteries, chest pain, dizziness or shortness of breath appear. After the nuclear stress test is completed, the images of rest and stress are compared.

Risks of the test

The nuclear stress test is a diagnostic method that usually does not have complications. However, that doesn't mean it's risk-free. Derivative symptoms such as dizziness, nausea, anxiety or headache are common.

Similarly, it is common for blood pressure to drop after exercise. Therefore, dizziness can be aggravated. Although it is more infrequent, in some cases arrhythmias appear. Some people may experience an allergic reaction to the radioactive drug.

The intensity of the test is progressively increased to assess the cardiac response.

Nuclear stress test results

To obtain the results of the nuclear stress test, the images of the heart obtained during rest and during exertion must be compared. This shows the areas that have not absorbed the radioactive dye well.

If you see an area that has not stained well during exercise, it is possible that there is a blocked coronary artery. Similarly, if the flow is also altered during rest, the arterial blockage may be severe. The same is also true when there was a previous myocardial infarction.

The test of choice to check for damage is coronary angiography. It is a technique that allows us to observe the interior of the coronary arteries. If there is a blocked area, a stent to increase the caliber.

Nuclear stress test is useful and safe

This technique allows to check the functioning of the heart and the state of its tissues. Not only does it help diagnose cardiac pathologies, but it can also serve to better direct treatment.

In addition, it is a safe test that has a low probability of complications. However, it is very important that the before and after instructions are followed in order to obtain adequate results.