Nuclear exercise stress test also known as thallium stress test is an imaging test used to diagnose how the blood flows from the heart while exercising and resting.
In this test, a small amount of radioactive element like thallium is injected into the patients through a vein which will flow along with the blood and will finally reach the heart.
A special camera known as gamma camera will then detect the radiation that is released by the tracer element and hence, will produce an image showing whether the heart is healthy or not.
This test helps to determine the conditions of heart like the size of the heart chamber, the ventricular functions, the myocardial perfusion, or if there is any harm to the heart muscle or any scar due to a heart attack.
This test, when combined with the exercise, will reveal the blood flow rate to the heart when a person is exercising as compared to when a person is resting.
2 Reasons for Procedure
The main reasons a patient may be recommended for nuclear stress test is if a doctor suspects any of the following conditions:
If there not enough blood flow from the heart under stress condition like exercising.
Normally, a patient can tolerate the test very well, but along with undergoing nuclear stress test comes potential risks.
The patient may experience wound kind of a feeling due the medication that stimulates exercise which will be followed by a warm feeling. The patient may also experience a headache, nausea, and a racing heart.
The radioactive material will be removed from the body through urine but in very rare cases, following complications may occur:
Arrhythmias (irregular heart beat)
Increased angina (pain from poor blood flow in the heart)
The patient will have to inform the doctor if he/she experiences any of these problems.
4 Preparing for your Procedure
In preparing for your nuclear stress test, you must follow your doctor’s orders. The doctor may advise the patient not to eat or drink for 4 hours before the test and if the patient is supposed to take a medicine then he/she is advised to take small sips of water in order to swallow the medicine.
The doctor will ask the patient to not to have products like coffee, tea, chocolate and other products that have caffeine, for 24 hours before the test.
There are certain guidelines which are needed to be followed regarding the intake of medicines:
Medications with caffeine: The patients are asked to not to have the medicines consisting of caffeine for example Excedrin®, Anacin®, diet pills and No Doz® for 24 hours before the test.
Asthma: If the patient is suffering from asthma then he/she will be advised not to take theophylline for 48 hours before the test and also to bring the inhaler along.
Diabetes: if the patient is having diabetes and is taking insulin in order to control the blood sugar level then he/she must notify the doctor. The doctor will tell the patient to take half amount of the insulin than the amount the patient take regularly and also to eat a light meal 4 hours before the test.
If the patient is taking a pill for controlling the sugar, then he/she is advised not to take them till the test is complete. If the patient feels that he/she is having low blood sugar, then this needs to the told to the doctor before the test.
Any heart medication: The patients are advised not to take following heart medicines on the day of the test:
Isosorbide dinitrate (for example Dilatrate, Isordil)
Isosorbide mononitrate (for example Imdur, ISMO, Monoket)
Nitroglycerin (for example Minitran®, Nitropatches, Nitrostat)
Dipyridamole (Persantine®): Stop taking 48 hours before the test.
The patient is also told to wear comfortable clothes on the day of the test. Further, the area where the test is to be conducted is under the supervision of the doctor. The approximate time the test will take is 2-3 hours, while the exercise part will last for 7-12 minutes.
5 What to Expect
Read on to learn more about what to expect before, during, and after your nuclear stress test. The test is always performed in the hospital or medical center under the supervision of the doctor.
The health care person or the nurse will insert an IV (an intravenous line) in the arm or hand through which a radioisotope or a radiopharmaceutical for example thallium or sestamibi, is injected.
This radioisotope molecule will flow along the blood and reach the heart. With the help of gamma camera, the radiations produced will be detected.
The test will be done two phases: (1) Resting phase; (2) Exercise phase and the doctor will decide which one will be performed first.
The patient is led onto a bed for 15-45 minutes so that the medication will reach the heart and then the patient will be led to an examination table where the patient will be told to keep the arms above the head and a gamma camera with the patient will click the pictures.
In this part, the patient will have to walk on a treadmill or pedal on a bicycle. If the patient is not able to do so, the doctor can also give some medication in order to stimulate the heart beat rate.
The blood pressure and the rhythm of the heart are also monitored during the exercise and when the heart starts working harder, the exercise will be stopped.
After around 30 minutes the patient will be led onto an examination table again and the gamma camera will picture the condition.
6 Procedure Results
The result of the nuclear stress test is mainly dependent on the reason for which the test is conducted, the age of the patient, any heart problem history and if any other medical condition persists.
The results can be categorized under two heading:
Normal results: The result is said to be normal if the blood flow in the coronary artery is at a normal rate.
Abnormal results: The results are said to be abnormal in following conditions:
Reduced blood flow
Any kind of scarring in the heart muscle due to heart attack
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