Echo with contrast

An echocardiogram is a test used to assess the structure and function of the heart by using sound waves. A contrast echocardiogram is used to improve echocardiographic resolution and provide an assessment of dynamic blood flow. A contrast or a special dye (a contrast agent), when used with an echocardiogram (echo), gives clear pictures of the heart. It is useful in patients who are obese, have lung problems, or have had previous chest surgery.

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In this blog, we will explore what an echocardiogram with contrast is, the dyes used for contrast, and their benefits and risks.

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What is a contrast echo?

It is a standard echocardiogram, with the exception that it requires an injection. A contrast medium is inserted into the vein of the arm in the presence of a cardiologist.

Two types of injections can be given:-

• Contrast echo ultrasound uses a contrast medium or a dye.
• Contrast bubble study using salt water.

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Types of echocardiogram

Different types of echocardiograms are:-

• Transthoracic echocardiogram.
• Transesophageal echocardiogram.
• Stress echocardiogram.

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Each has different benefits in diagnosing and managing heart disease.

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Techniques used in echocardiography

Several techniques are used to create pictures of the heart. Some of them are:-

1. Two-dimensional ultrasound is the most common approach.

2. Three-dimensional ultrasound: Advances in technology have made 3D imaging efficient and useful. A 3D echocardiogram enables us to view various parts of the heart from different angles.

3. Doppler ultrasound: It shows the speed with which the blood flows and its direction.

4. Color Doppler ultrasound: It shows the direction of blood flow using different colors to highlight the direction.

5. Strain imaging: It reveals which heart muscles are under strain and helps detect early changes in the heart.

6. Contrast imaging: A contrast agent is injected into the vein, which is visible in the images of the heart.

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Contrast materials and how they work?

When undergoing an ultrasound, CT scan, or MRI, the type selected depends on the specific information it can provide about the targeted body parts. Contrast materials, also known as contrast agents, enhance the diagnostic ability of these imaging tests.

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The contrast materials alter the way imaging tools interact with the body, making structures or tissues appear different in the image. It helps physicians to diagnose medical conditions by improving the visibility of the structure they intend to see.

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Contrast materials are used in the following ways:

• Swallowing by mouth.
• Administered by enema through the anus
• Injected intravenously or intra-arterially through veins or arteries
• Injected into spaces in the body

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The contrast material is absorbed by the body and eliminated through urine or bowel following the procedure.

Contrast bubble study using salt water

It is used to assess a tiny hole or a problem at the back of the heart and is usually carried out in people who have suffered a stroke at a young age with no apparent cause.

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The saltwater is agitated in the syringe to create bubbles, which are then injected into a vein. The scan will help a doctor identify when the bubbles cross from the right side of the heart to the left side. The tiny bubbles dissolve into the bloodstream and are expelled from the body through the lungs.

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It is usually repeated two or three times along with the Valsalva maneuver. (Holding your breath, you blow the air into your cheeks.)

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How do microbubble contrast agents work?

• The microbubble contrast agents are made up of tiny gas bubbles, which are smaller than RBCs
• These bubbles reflect ultrasound waves, enhancing the ultrasound image of the heart and producing clear pictures.
• When injected into the bloodstream, the ultrasound machine can detect the difference between gas in the bubbles and the surrounding tissues, creating sharper and more detailed images.
• These bubbles are safe and dissolve within 10 to 15 minutes; the air is removed when we exhale.

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Why is contrast needed in echocardiography?

The contrast makes it possible for us to see the heart chambers and walls easily, especially in patients with obesity, lung disease, or those who have had a previous surgery.

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The contrast enables us to see blood flow to the heart muscle and is useful in stress echocardiography, where the heart is monitored under stress for poor blood supply or any blockage.

• Even and full contrast filling shows the heart muscle to have normal blood flow and function.
• Poor or uneven contrast signals reduced blood supply
• No contrast in a non-moving part of the heart indicates that the heart muscle is no longer alive

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Improved visualization

It increases the visibility of heart chambers and walls, especially of the left ventricle.

It enhances the accuracy of edge detection, which aids in accurately measuring heart size and function.

Helps to see heart segments that are not seen well on standard echo

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Assessment of blood flow

Improves Doppler signals, especially for areas like the aorta and pulmonary veins

Shows blood flow in the heart muscle, which is essential in stress echocardiography to check for poor circulation or blockages

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Detection of heart conditions

It detects blood clots in the left ventricle and distinguishes them from tumors.

It diagnoses cardiomyopathies or abnormal heart motion

Filling defects that help us assess ventricular function, the ejection fraction

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Other applications

An agitated saline bubble study helps detect holes or congenital heart defects, such as PFO or ASD.

It evaluates blood flow in patients suspected of coronary artery disease.

Contraindications to contrast echocardiography

• Contraindications for contrast echocardiography include known hypersensitivity to contrast agents or their components. Hypersensitivity to the contrast agents is rare.
• Ventricular arrhythmia or high risk for arrhythmias due to QT prolongation
• Respiratory failure
• Emphysema, pulmonary embolism, and pulmonary hypertension
• In bidirectional shunts, microbubbles bypass the lungs and enter the arterial circulation, causing complications.
• A contrast agent should not be injected into the arteries; instead, it should be administered intravenously.
• Pregnancy and lactation: The Safety of contrast agents during pregnancy and lactation has not been established, so they are contraindicated
• Hepatic disease is a relative contraindication, as liver metabolism is responsible for the clearance of contrast agents
• Recent myocardial infarction
• Patients experiencing worsening symptoms for the last seven days
• Patients with recent acute coronary syndrome or unstable cardiac disease

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Risks and complications

Risks and possible complications of contrast echo are:

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The IV site may develop swelling and bruising because of excessive bleeding

Allergic reactions to contrast material may occur, resulting in rashes, hives, difficulty in breathing, swelling in the face, mouth, lips, or tongue.

Allergic reactions may cause dizziness, weakness, fatigue, palpitations, headache, and nausea.

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The procedure

Echocardiography uses sound waves to take pictures of the heart as it beats. During the test, a contrast agent is injected into the vein to obtain detailed and clear images of the heart. A contrast echo is performed when the standard echo does not provide clear images or detailed information about the heart. From start to finish, it takes about 30 minutes to complete.

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Before the test

Do not take a heavy meal before the test.

Wear a two-piece outfit, as you may be required to undress above the waist and wear a hospital gown.

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Inform the technician if you have

• A heart or a lung problem
• If you are allergic to any blood products or medicines
• If you are taking any medicines, vitamins, or herbs
• Pregnant or breastfeeding

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During the test

• An IV line is placed into a vein in your arm or hand
• Small electrodes are placed on the chest to monitor the heart rate
• Gel is placed on your chest, and a handheld device called a transducer is moved over the chest in the region of the heart. The transducer sends sound waves and receives them, creating pictures on the monitor of a computer
• The contrast agent is injected through the highway line into the blood
• You may often be asked to change your position and hold your breath to get sharp images
• After the test is completed, the IV line and gel are removed from the chest

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After the test

• Depending on the results of the echocardiogram, you may need to rest for a short period.
• You may be monitored until your vital signs return to normal, after which you will be able to go home.

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Conclusion

An echocardiogram with contrast is a specialized type of heart ultrasound that utilizes a contrast agent or dye, injected into a vein, to enhance the clarity of the images. The contrast helps doctors see the heart’s chambers, valves, and movements clearly, especially in cases where standard ultrasound images are blurry. Contrast echocardiography at Gauze improves image quality during both rest and stress echocardiography, providing a safe assessment of cardiac structure, function, and coronary flow.