Does A Nuclear Stress Test Show Blocked Arteries?

Does A Nuclear Stress Test Show Blocked Arteries?

Does A Nuclear Stress Test Show Blocked Arteries

Our heart has four chambers namely right atrium and ventricle & left atrium and ventricles and has a rich blood supply, which comes from the right and left coronary arteries. When coming on systemic circulation it starts with the pumping of blood from the left ventricle into the largest artery known as the Aorta. From the aorta, it circulates to the other parts of the body. Any disturbance in the circulation of blood from arteries of heart leads to serious diseases like myocardial infarction, ischemia heart diseases, and coronary diseases. To know the disease there are many investigations are advised.

Does A Nuclear Stress Test Shows Blocked Arteries

The nuclear stress test is one of the tests which helps to detect the blockage of the arteries. This test is done with the use of a radioactive agent which is injected in the arm to know the flow of blood. This test shows the two images of your heart, first during at rest and second during at exertion. To know your heart whether it is at the risk of disease, this test will help to know the function of the heart. To come upon the accuracy of this test, its accuracy is more than other investigation but still, it depends upon the way the radioactive agent is injected. But if the abnormal nuclear stress tests result is present, the reasons for it are described below in the article.

The main purpose for performing this test is to identity the blockage of the coronary arteries. This test show the blood supply to the heart muscles when the patient is in stressed by doing exercise and stressed which is induced by giving medication and to know that which part of the heart muscle is getting low blood supply. This is done by injecting radioactive agent when it reaches to the heart and pumped to the muscles of the heart through coronary arteries. 

To know whether nuclear stress test is how much relevant so that one can go with the test, for it one should have a thorough knowledge of this test, its use, procedure, its results with interpretations and with its risk factors. This will give you knowledge regarding the questions which arise in the mind that does a nuclear stress test shows blocked arteries?

What Is Nuclear Stress Test?

The nuclear stress test is done to get an image of the function of the heart by the use of a radioactive agent called as radionuclide which is injected. This test is done in both rests as well as activity time to know the flow of blood to the heart muscles. This test is also known as Myocardial Perfusion Scan.

How to Check Block Arteries

There are two type of nuclear stress test is done

  • Nuclear stress test during exercise.
  • Nuclear stress test during pharmacological medication

Nuclear Stress Test During Exercise

This test is done to know that which area of the heart muscles is getting decreased blood supply during an exercise. This test is done by injecting the radioactive agent from the arm or hand into the veins while the patient in a rest, from which this radioactive agent get circulated in the blood and goes to the heart and from heart it goes to the muscles of the heart. To getting the image a special machine called gamma camera is used which takes the image of the heart while the patient is in the rest (lies on the table). This scanning of the heart for getting the images last for 15-20 minutes. This phase of the test is called as Rest Scan. Arteries which are blocked or any area which is getting insufficient blood supply will have appeared on the scan as a cold spot or defects because that part of the heart muscles will not able to absorb the radioactive agent.

Nuclear Stress Test During Pharmacological Medication

This test is done for those patients who are physically not fit to run on the treadmills due to any physical or medical conditions. In this method, the medicine is given to the patient by which it either dilates the coronary arteries or increases the heart rate. This medicine produces the phase which is equal to the phase which is produced due to exercise. Rest of the procedure is the same for getting the image of the heart by injecting radioactive agent. But here the next dose of radioactive agent is given to the patient when the stress is at peak level.

Instructions For The Patients Before The Procedure Is To Be Done

There are a few points which every patient should know before he/she is going for the test. These are as follows

  • Anything’s which contains caffeine in it should be avoided before 24 hrs from the test to be performed.
  • Fasting should be done before the 4 hrs from the test.
  • Do not use any cosmetic creams or any lotions on your chest area before performing the test.
  • For diabetic patients please consult your doctor before performing the test.
  • If any kind of medications or any supplements you are taking to inform the staff and doctors.
  • Before performing the test a consent form has to be filled by the patient. So read it very carefully and if you have any query you are free to ask any question.
  • If you any pacemaker or having defibrillator than inform to the staff.
  • For pregnant women’s please consult your doctor either she should go for the test or not.
  • Any medical conditions if having than also informed the staff.
  • Should be dressed in which you will feel relax and comfortable including your shoes also.

Nuclear Stress Test Procedure

This test can be performed at any medical centers or hospitals. This procedure is done under the patient’s medical conditions and the physician’s experience and practice. The following steps are to be followed for the test

  • Patient at the first is asked to remove all the ornaments. As it can creates disturbance for getting the images.
  • Intravenous catheterization is done in the arm from where the radioactive agent will be injected.
  • After than ECG machine with lead and for measuring blood pressure a cuff will be placed on the arm.
  • For nuclear stress test during exercise, the patient has to exercise on treadmill with increased intensity. After which the ECG and blood pressure will be measured. Once the patient reached at the maximum exercise point which will be determined by the patient’s age and heart rate, than the radioactive agent will be injected and the patient will have to continue the exercise for at least 2-3 min so that it circulates through the whole body and the patient will allow for rest.
  • For pharmacological medicinal nuclear test instead of exercise, the medicine is injected through intravenous which will dilate the arteries or will increase the heart rate. At this point, the heart rate and blood pressure will be noted and then the radioactive agent will be injected.

For injecting radioactive agent for this procedure mostly thallium or technetium radionuclide are used.

Results with Interpretations

The result of this test depends on the following factors. These are

  • The flow of blood to the muscles in both exercise and rest.
  • The flow of blood in rest, not in exercise.
  • Due to insufficient radioactive agent pumped to the parts of the heart.
  • Due to low blood flow in rest as well as exercise.

With proper management, the result is mostly accurate so that one can easily believe in the test. But the patient show should have adequate blood in the body so that the radioactive agent can be easily circulated in the heart muscles and shows the blocked arteries so that one will not get abnormal nuclear stress test results.

Risks of Nuclear Stress Test

Generally, it is safe, but few people can be at risk if there is any medical condition present. But these conditions are rarely presented.

  • Many people have allergic reactions to the agent.
  • Some people can have a heart attack during the test but it is most rare.
  • Some people can have abnormal heart rate (arrhythmias) during exercise or due to medications.
  • Some people can have chest pain or dizziness.
  • Some people can have low blood pressure.

After going through this article for those people who think that does nuclear stress test can show blocked arteries, hopefully, they get the full knowledge about the test. If still, they found abnormal nuclear stress test results than one should consult the doctor to know the cause of abnormal results, as mostly doctor prefer to go with this test because this nuclear stress test accuracy is more than any other investigations.

Reviewed By:

Dr. Kaushal M. Bhavsar (MBBS, MD)

Assistant Professor in Pulmonary Medicine, GMERS Medical College, Ahmedabad