18 June 2018
Dobutamine Stress Echocardiography
Dobutamine Stress Echocardiography
The treadmill is a cardiology exam that evaluates whether the heart receives enough oxygen during exercise.
However, for various reasons, it may be difficult or impossible for some people to walk on a treadmill and provide sufficient effort for the results of the examination be conclusive.
A substitute test may then be requested by your doctor.
The Dobutamine stress echocardiography is one of the possibilities.
What is the exam?
This exam consists of comparing the contraction of the heart at rest with its response after the injection of a product into a vein that simulates physical activity by increasing heart rate and blood pressure.
The results of a cardiac ultrasound allow for this.
The purpose of the exam
We want to "see" how the heart reacts to dobutamine as if you were exercising.
The goal maybe to replace the treadmill test for people who cannot walk on one or cannot do so efficiently.
For other patients, the goal is to confirm or clarify the result of an abnormal or inconclusive treadmill test by pinpointing the region of the heart where a coronary blockage may be present.
Relatively easy examination
Although longer than a simple ultrasound, it is a relatively easy test.
An appointment is necessary
You must schedule an appointment for this exam done externally.
No special preparation
No preparation is required. It is not necessary to be fasting. However, it is recommended to eat a light breakfast beforehand.
Any medication in the beta-blocker categoryshould be stopped 24 to 48 hours prior to this test because they counteract the effect of dobutamine on your heart.
Your doctor will give you instructions if needed.
It is easy to know if your medication is in this category. All beta-blocker pills names end with the letters "lol".
For other medication, if you have not been given any specific instructions, take them as usual.
How does it looks like?
The test has two parts: A series of photos of your heart at rest and another series of photos under the medication of dobutamine.
The preparation stage
The day of your test, present yourself at the reception.
You will then be asked to remove all your clothes and put on a hospital gown.
A list of your médication
The technologist needs the list of your medication to complete your file. Make sure your list is up to date.
A small catheter
Then, you will be asked to lie down on a bed so a small catheter can be installed in a vein in your arm.
Electrodes on your skin
Electrodes are also placed on specific places on your body. These sensors, well attached to your skin, record the electricity emitted by your heart during the exam.
For a better electric contact
The surface of our skin can modify the amplitude of the heart's electricity. To help better capture this electricity, the technologist will lightly scratch the skin with small sandpaper.
Blood pressure monitor
Your blood pressure will be recorded at different times during the examination. The necessary equipment will therefore be installed on your am prior to the exam.
Echocardiography at rest
The examination begins with a first echocardiography commonly called a trans thoracic ultrasound at rest.
Cardiac echography -1st part
A cardiac ultrasound allows the evaluation of the anatomy and the heart’s functions using ultrasound.
Same as for pregnant women
It is the same kind of test used to see the baby in pregnant women.
The difference is that, in this case, we will be looking at the heart and its ability to contract.
Trans thoracic echocardiography
The technologist or doctor places the ultrasound probe on the chest. Ultrasound will pass through the chest.
The technologist or doctor concentrates his recording on the heart’s work, particularly the left ventricle. Several shots are required to see it from different angles.
Once these images are recorded, we go on to the second part, which is that of dobutamine.
We are now ready for the "simulation at effort" part
Intravenous dobutamine -2nd part
Gradual injection of dobutamine
Dobutamine is a medication that is administered in progressive doses through the veins by evaluating its effect on your blood pressure and your heart rate.
This medication is given to you using the catheter installed in the vein of your arm.
Throughout this phase of the exam, your blood pressure and heart rate are monitored and recorded, and electrocardiograms (ECG) are recorded.
The purpose of the exam is to speed up the heart
The purpose of the exam is to have your heart rate boosted sufficiently by dobutamine for the test to be valid.
This heart rate is based on your age.
The administration of dobutamine begins
The dobutamine is injected through the catheter. The dose is gradually increased every 3 minutes. The duration of each period offers the time necessary for your heart to respond to the medication. In other words, it will accelerate and pump harder.
Once the desired heartbeat is attained, we move to the next level until we get the heart rate needed to complete your exam.
Do not be afraid
While the medication is administered, you will probably feel your heart beat faster and faster.
Do not worry because this is the purpose of the exam, as if you are gradually climbing a hill.
Second Ultrasound-Final Part
Once the target heart rate is reached, the ultrasound is repeated to compare with the resting images.
The technician or doctor may ask you to hold your breath to get better pictures.
Once images are recorded, the administration of dobutamine stops.
Effects are short-lived
The effects take a few minutes to disappear completely. You may also be given a drug to slow your heart up to the heart rate of the start of the test.
And it's over
After the exam, you can get dressed and after a moment of observation in the waiting room with the person accompanying you, you can leave.
The results are sent to your doctor
The results will be communicated to the doctor who requested the examination.
You can request a copy for another doctor
You may ask that a copy of the result be sent to another doctor. All you need to do is give the name and contact details of this doctor to the staff.
You can ask for it at any time.
Comparison of images
Once the exam is completed, the cardiologist compares your resting images with those taken during dobutamine stimulation.
Why speed up the heart? What are we looking for?
The heart is a muscle. Increasing its work requires more oxygen. It feeds on arteries that are called coronaries. Coronary heart disease is responsible for blockages in the coronaries. These blockages can limit oxygen to the heart muscle. Simulating physical activity with dobutamine stimulates the heart and increases its work as if it were exercising.
Normal examination results in increased contraction of the heart in all regions compared to resting images. If of one or more blockages prevent oxygen from being delivered in sufficient quantity, the heart suffers. The contraction will be less vigorous on certain regions of the heart compared to the images at rest.