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Stress and Test October 16, 2007

Posted by tomography in Nuclear Medicine, Picture of the week, SPECT.
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heartvascularstimage1.jpgThe stress test shows if your heart receives enough blood from its own arteries to work harder, safely. Taking the stress test also helps your doctor know what type of exercise and how much is right for you.

The role of nuclear cardiology

The resting heart muscle’s blood supply needs are usually well met even in the presence of blocked arteries. When the heart is stressed either by exercise or chemicals, the demand for blood increases. The blood flow through the blocked arteries – while adequate at rest – may not be able to keep up with the demands of a stressed heart. This can show up on the pictures of the heart taken after stress. This is the principle behind all the stress tests. The word stress test is used for any means used to increase heart muscle’s demand for blood. This can be done by exercise or by chemical means.

The patient either walks on a treadmill, or is given iv. (intravenous) medication which simulates exercise, while connected to an ECG machine, used to record a 12-lead ECG. The level of exercise is increased by 3 minute stages, of progressively increased grade (incline) and speed. The patient’s symptoms, and blood pressure (BP) response are repeatedly checked.

However, some patients cannot exercise adequately. Patients with lung disease, arthritis, or disease in the leg vessels may not be able to walk. Patients with some medical conditions should not walk on the treadmill. For these patients the doctor can use a drug to affect the blood supply to the heart and simulate the effects of exercise.

It is done to identify the cause of chest pain or chest discomfort which can occur with blockages in blood flow to the heart, to monitor heart function in people with known heart disease, and to determine the response to medications or after angioplasty or bypass surgery.

If radioactive isotopes are also used (commonly, Technetium Tc99m Sestamabi and rarely, Thallium-201), then it is usually called a Nuclear Stress Test (NST).stresstest_1.jpg

The most commonly used NST is the Dobutamine Nuclear Stress Test (Cardiolite). (There are four types of cardiolite stress test. Excersize, Persantine, Adenosine and Dobutamine stress test.)

It is similar to excersize stress test except for the fact that a medicine called Dobutamine is used to stress the heart. During this test, Dobutamine is infused at a gradually increasing rate to increase the heart rate to a desired level. This drug has the effect of increasing the force of contraction of the heart, the heart rate and blood pressure. This stresses the heart muscle, which simulates exercise.

“Cardiolite is a short-lived, radioactive element that is absorbed by the heart muscle and allows your heart to be seen by the camera. Cardiolite images allow the physician to indirectly look at the blood flow to your heart.”

Areas that do not have adequate blood supply pick up the tracer very slowly or not at all.

Take a look at one of the “picture of the week”s.

Cardiolite is injected while you are at rest and while your heart is under stress. Rest and stress images are taken to allow doctors to compare how much blood flows through the heart muscle during stress and at rest.
(Most patients experience no side effects.)

Persantine is a coronary vasodilator that is used as a diagnostic agent in nuclear stress testing. Persantine works by increasing the blood vessel circumference of the coronary arteries (arteries that feed the heart) in order to increase blood flow to the heart.”

Adenosine is an antiarrhytmic agent, works as a vasodilatator, similar to Persantine. Side effects include: chest pain/pressure, headache, nausea, dizziness, shortness of breath. Some patients experience a burning or stinging sensation at their IV site because Persantine is more acidic than your blood. Persantine is contraindicated in patients who have a hypersensitivity to this drug. If needed, the antidote Aminophylline is given to the patient.

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Comments»

1. Stress Management » Stress and Test - October 18, 2007

[…] Find the link to this great post here […]

2. Raymond L Masters - November 17, 2007

Hi; I need to find graphic excersize charts so my mother-in law can do excersizes at home. she has heart and lung problems and her Dr suggested excersizes but she will not go out and he does not have charts showing her what excersizes to do. He wants her to go to a clinic but she will not go out. Can you give me any information as to where we can get the information on paper so she can see the excersizes and do them at home with my wifes help?
Thanking you in advance: Ray Masters

3. tomography - November 19, 2007

Dear Raymond!

Our first advice would be for you to persuade your mother-in-law to go out. If possible and it really doesn’t mean her a big effort physically, you should start with simple walking outside. As she has lung disease as well, it is advisable anyway to stay outside because of fresh air. Walking can help a lot! Don’t forget to “train” gradually!
BUT as we don’t know what problems she has with her heart and lungs exactly, honestly we shall not give you sort of “tele”advices or rehab training programs. Your health care provider can help you find a program that matches your level of fitness and physical condition.
If you want your mother-in-law to do some homework anyway, you can find many exercise guidelines on internet – wherefrom you can choose the best one for her condition. DON’T forget to be gradual!
Apropos! Diet is very important also.
If you have any questions (maybe you want us to be more factual), feel free, we’ll try to answer.
András and Imre

4. Susan - June 10, 2008

Yesterday I had a nuclear stress test, using the treadmill. I came through with flying colors. But I have had a vicious headache for over 24 hours. I thought it was because I was getting a flu or something but then realized that maybe it was from the injection. If it is, how long will the symptoms last? I think it is easing up, but is still significant.

5. tomography - June 11, 2008

Susan,
we usually do not give medical advice, but I think in this case I can make an exemption. The headache you are feeling is probably a mild reaction of your body’s to the pharmaceutical, and it should clear up soon. If it does not go away by 2-3 days, consult your physician! Don’t be scared, though.
Andras

6. Andros - October 31, 2008

Let’s see if I can ask the question in a way which you might actually answer…

Are there any adverse side affects to the meds used in the ‘induced exercise’ stress tests which could cause an irregular heartbeat?

Thank you.


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