What is an Echocardiogram?

Echocardiography is a procedure in which a probe or handheld device uses high-frequency sound waves to take pictures of the heart's valves and chambers. These sound waves produce dynamic images of the heart, called an echocardiogram. The heart's pumping action is shown in a graphic outline.

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Ultrasound of the heart, also known as an echocardiogram (echo), checks the heart's structure and function. It is done to observe how the heart and its valves work. It is a versatile, non-invasive, and portable test that can be easily used in sick patients, emergency rooms, or for walk-in symptomatic patients.

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It does not use ionizing radiation, as in X-rays and CT scans. Echo is often used in conjunction with Doppler ultrasound and color Doppler techniques to evaluate blood flow across the heart. This blog will explore a diagnostic imaging technique that uses ultrasound waves to assess the heart's structure and function.

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Echocardiogram versus ECG

An echocardiogram and an electrocardiogram are diagnostic tools for the heart, but they provide different types of visuals. An echocardiogram (echo) observes the overall structure and function of the heart and produces dynamic images of the heart.

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On the other hand, an ECG checks the heart's electrical activity and prepares a graph rather than pictures of it. The lines on the graph show heart rate and rhythm.

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What does an echocardiogram diagnose?

Echocardiograms help display the size, structure, and activity of the heart. They diagnose heart problems and help doctors decide the best course of action. They even monitor changes and improvements.

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• Heart attack: It can indicate a heart attack, thus helping a doctor see if the heart muscle is not pumping well.

• Blood clots or tumours: Echo is a non-invasive tool that detects thrombus and cardiac masses, such as tumours.

• Aortic aneurysm and aortic dissection: It helps locate a wide, weakened aorta, or the size of an unruptured aortic aneurysm, and identify fibrosis or thrombus in the aorta.

• Pulmonary hypertension: It helps to indicate the presence of pulmonary hypertension.

• Congenital heart disease: Septal defects and holes can be easily identified by it, especially in infants and young children.

• Heart valve disease: It can detect flow abnormalities across valves, such as regurgitation (leakage) and stenosis (narrowing), as well as abnormal growths, which may indicate infections like endocarditis. 

• Pericardium: It checks for pericarditis (inflammation of the pericardium, the outermost layer of the heart) or Pericardial effusion (when fluid or blood fills between the layers of the heart).

• Heart failure: It detects weak, stiff, or thick heart muscles, which are signs of heart failure.

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When is an echocardiogram advised?

An echocardiogram is advised if someone has heart problems. The signs and symptoms that indicate a heart condition are:

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• Arrhythmia.

• Shortness of breath.

• High blood pressure.

• Leg swelling.

• Abnormal ECG results.

• Heart murmurs, unusual sounds between heartbeats.

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Principle of echocardiography

For an echocardiogram, a probe or a handheld device uses high-frequency sound waves to take pictures of the heart's valves and chambers. It evaluates the pumping action of the heart.

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Echo is often used in conjunction with Doppler ultrasound and color Doppler techniques to evaluate blood flow across the heart. Echocardiography uses the principle of ultrasound to visualise the heart and its vessels. 

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• The sound frequency used is in the range of 1-10 MHz.

• Raising the probe frequency increases resolution, but at the cost of penetration.

• As the probe frequency increases, resolution improves, and penetration decreases.

• Due to the thick chest walls, probes with a frequency range of 2-5 MHz are used in adults.  

• The high-frequency probes (3.5 to 7.5 MHz) are used for paediatric applications due to the thin chest wall.

• Echocardiography assumes that sound travels at a constant speed through soft tissues at 15400m/s for image reconstruction.

• The transducer, which has a piezoelectric crystal, emits a beam of a given frequency, which is reflected from cardiac and other structures and returns to the transducer.

• These returned ultrasound waves then display images of cardiac structure on the monitor screen and can be stored on a hard disc or optical disc.

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Techniques used in echocardiography

Different techniques are used to perform echocardiography.

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They are:

• Two-dimensional (2D) ultrasound: It is the most commonly used technique that produces sections of heart images on the computer screen.

• Three-dimensional (3D) ultrasound: The advanced technique shows how well the heart pumps blood with greater accuracy, giving flexibility to the sonographer to observe the heart from different angles.

• Doppler ultrasound: Reveals the speed and direction of the blood flow.

• Colour Doppler ultrasound: It highlights the direction of blood flow using different colours.

• Strain imaging: It detects heart muscle movement and helps in diagnosing early signs of heart disease.

• Contrast imaging uses a contrast dye (some people are sensitive to these contrast agents) injected into one of your veins to visualize details. 

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Transthoracic echocardiogram

To most people, a heart echo means a transthoracic echocardiogram. A handheld transducer or probe is used on the side of the chest to send sound waves to the heart. The waves bounce back from different parts of the heart to the probe. It creates images that can be stored and are visible on the screen.

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Preparing for a transthoracic echocardiography

Not much preparation is required for this type of echo. In general.

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• Avoid eating or drinking excessively.

• Take your medicines as you do.

• Wear something comfortable.

• Leave all valuables at home.

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How is a transthoracic echocardiography conducted?

• You may be asked to remove all clothes from the waist up, and you will be dressed in a hospital gown.

• The sonographer places several sticky electrodes on the chest to attach the electrocardiograph monitor. The ECG will record your heart's electrical activity during the test.

• At the examination table, you may be asked to lie on your left side.

• A probe with gel will be used on several areas of your chest. The gel helps to get a clear picture.

• Swishing sounds may be heard throughout the test. It is normal.

• You may be asked to hold your breath for some time and not move to different positions.

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Transoesophageal echocardiogram

It takes pictures from the inside of the chest. It shows the heart and valves in great detail compared to a transthoracic echo. Using a long, flexible tube, the sonographer guides a small probe down the throat and oesophagus. Although it is minimally invasive, it often causes mild temporary discomfort to the throat.

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• It is done to give a detailed picture of the aorta or the back of the heart.

• To check for blood clots.

• To evaluate the mitral valve and the aortic valve.

• In obesity or lung disorders.

• If a transthoracic echo is not possible for any other reason.

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Preparing for a transoesophageal echocardiography

You must inform your doctor before your problems (if any) related to

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• Oesophagus like a hiatus hernia.

• Swallowing.

• Sleep apnea.

• IV drug use.

• Medications you are on for
  
  • Sleep issues
  • Anxiety
  • Pain

• Do not eat or drink 6 hours before the test.

• Take your medicines as usual with a small sip of water.

• Question the doctor about your diabetes medication if it applies to you.

• Wear comfortable clothes.

• The procedure is done under sedation, so someone must accompany you to drive you home.

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The procedure usually lasts 20 to 40 minutes and is done under sedation. No pain or difficulty in breathing occurs during the procedure. The throat may appear sore for a few hours. A small percentage of people experience gastric injury or bleeding.

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You can’t eat or drink anything for the next 30 to 60 minutes after the procedure, and should also avoid hot liquids. Within 24 hours, you can resume your normal duties.

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Exercise stress echocardiography test

The exercise stress echo evaluates the heart's function when it is beating rapidly or is under stress, and the test is commonly known as a stress echo or echo stress test. It is commonly done to diagnose coronary artery disease. It is also done to diagnose or monitor other conditions like

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• Cardiomyopathy.

• Congenital heart disease.

• Heart failure.

• Heart valve disease.

• Pulmonary hypertension.

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The exercise stress echocardiogram

Electrodes are attached to the chest. These electrodes are then connected to an ECG monitor that tracks heart rate and blood pressure. While you are resting, your ECG and echocardiogram are also done. 

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Exercise is performed on a treadmill or a stationary bicycle, starting slowly and gradually increasing the intensity over time. One needs to continue exercising until the symptoms or the target heart rate, depending on the age and fitness level, are reached.

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After the symptoms ( Pain or discomfort in chest, arm, or jaw, shortness of breath, dizziness, and lightheadedness) appear or the target rate is achieved, an echocardiogram is repeated. It takes almost an hour to complete the test.

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The different types of stress echocardiograms are

• M mode: It produces a simple picture of the heart and is used to obtain the heart structure.

• Doppler: This test can measure how blood flows through the structures in the heart. It helps to assess how well the heart is functioning.

• 2-D: It provides a picture of motion and structure in the heart.

• 3-D: It creates pictures in three dimensions.

• Nuclear: A contrast stress test uses a small amount of radioactive dye to produce a picture of how blood moves through the arteries.

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3D Echocardiography

A 3-dimensional echocardiogram uses transesophageal or transthoracic echocardiography to create a 3D image of the heart.  It takes multiple pictures from different angles. A contrast agent is used to gain a clear picture during imaging.

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It is used

• Before heart valve surgeries.

• Diagnose heart problems in children.

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Foetal echocardiography

It is a specialised ultrasound that examines the structure and function of the baby’s heart in the womb. The test is done between 18 and 24 weeks of pregnancy. The transducer is placed over the abdomen of the pregnant woman to check for heart problems in the fetus. It is a safe test for an unborn child as it does not use radiation like X-rays.

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Risks of an echocardiogram

An echocardiogram poses no risk, as it is a non-invasive procedure. A transoesophageal echocardiogram may cause a reaction to the sedative or cause a sore throat or minor injury, rarely. A stress echocardiogram may cause minor complications from exercise or any medication used. Other risks may even depend upon your medical history.

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Limitations of echocardiography

Echocardiography is a valuable tool for assessing heart health, but it still has limitations.

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• Echocardiograms do not give a detailed image of coronary arteries and are also unable to detect blockages or atherosclerotic plaques unless they are large.

• It does not measure pressure inside the heart chamber as it relies on sound waves that may be distorted by fluid in the chamber. It may be difficult to obtain an accurate image if the heart's anatomy interferes with sound transmission.

• Echocardiogram reveals structural defects, but is unable to identify whether they are a cause of symptoms or the problem. It identifies significant structural defects such as congenital heart disease or valve dysfunctions, but it can overlook abnormalities like septal defects or minor valve prolapse.

• It gives limited information on arrhythmias or irregular heartbeats that indicate underlying heart problems.

• When blood flow to the heart muscle is reduced, it is challenging to detect reduced flow solely by echocardiography. Functional tests, such as imaging techniques like MRI or CT scans, are needed.

• Image quality may be reduced in individuals with obesity or lung disease due to poor acoustic windows.

• It is technically complex and costly, and is often a limited resource in poor settings such as rural areas or developing countries where cardiac diseases are more prevalent. 

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Interpretation of echocardiography

An echocardiogram is an ultrasound image of the heart’s internal structure. A normal echocardiogram displays the following results:

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1. Heart size: It indicates that all four heart chambers, atria and ventricles, are of normal size; the internal dimensions of the chambers and the volume of the chambers are of normal size.

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2. Wall thickness: It indicates that the thickness of the heart's wall and septum is normal.

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3. Heart valves are intact and of normal thickness and function properly.

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4. Blood flow: It indicates that blood flows through the chambers, is normal, and flows freely without any disturbance.

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5. Ejection fraction: It measures the amount of blood pumped out in each heartbeat. It is 55% to 70% in adults, 

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6. Abnormal structures and fluid: A normal echo will show the absence of any abnormal tissue, clot, tumour, or other abnormal fluid in the pericardium.

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Conclusion

An echocardiogram is a safe, non-invasive test that uses sound waves to create dynamic images of the heart. An echocardiogram diagnoses heart conditions, such as valve problems and heart failure, as well as congenital (since birth) disabilities. The echo provides valuable information on the heart's size, pumping strength, and valve function. 

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With advanced technology and clinical expertise, Gauze delivers reports that help you take the right steps towards better health. Gauze offers AI-powered solutions, backed by an expert team of cardiologists, ensuring that every echocardiogram is carefully analyzed.