What Does an Electrocardiogram Show?

You have had blood tests and an ECG, and now the doctor has advised you to undergo an echocardiography (echo). What is it that an echocardiogram shows that an ECG cannot? The echocardiogram displays the heart's structure and function in real-time motion, unlike an ECG, which records the heart's electrical activity. It allows the doctor to see the heart beating, as well as the chambers filling and emptying. The valves open and close, allowing the blood to flow through.

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If you experience chest pain, shortness of breath, fatigue, or lightheadedness, and your ECG is inconclusive, an echocardiogram can help diagnose heart disease.

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In this blog, we will explore why an echo is recommended, what it reveals, and its limitations.

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What is an electrocardiogram?

Cardiac echocardiography is a safe and noninvasive test that enables doctors to use cardiac function data to diagnose heart diseases.

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Echocardiography utilizes sound waves to generate real-time images of the heart. The image is called an echocardiogram. It enables doctors to assess the heart's and its valves' functioning.

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Working principle of an echocardiogram

A probe or transducer emits sound waves at a frequency that the human ear cannot hear. The transducer is placed on the chest at certain locations and angles. It causes the sound waves to bounce off the heart structures. These sound waves are sent to a computer, which creates moving images of the heart on the screen.

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Types of echocardiograms

• Transthoracic echocardiogram (TTE)

It is the standard echocardiogram, which creates pictures of the heart from outside the body.

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• Transesophageal echocardiogram (TEE)

A clear and detailed picture of the heart structures can be obtained using this method when the probe is inserted into the esophagus. It provides details about the structure of the aortic valve and the body’s main artery, called the aorta.

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• Fetal echocardiogram

It allows healthcare professionals to see the heart of an unborn baby and is usually performed in the second trimester of pregnancy.

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• Stress echocardiogram

It is done. To check how the heart responds to physical activity or stress. It is usually done when it is suspected that you are having coronary artery disease.

Healthy heart function

A normal heart has chambers, vessels (arteries and veins), and valves- the blood flows in a circulatory pattern from

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body - heart - lungs - heart - body

When all chambers and valves function correctly, the blood is pumped through the heart to the lungs for oxygen, then back to the heart, and out of the body to supply oxygen. When valves, vessels, or chambers are malformed, this circulatory pattern is disturbed.

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What does an echocardiogram show?

It shows the structure and how well the heart is pumping blood. It  shows

• Heart conditions
• Valve problems
• Muscle damage
• Structural abnormalities

The primary function of an echo is to help in calculating the ejection fraction and assessing the condition of the heart valves.

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• Pumping efficiency

They help evaluate ejection fraction, which indicates how well the heart pumps blood.

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• Heart valve function

It reveals if valves are leaking (regurgitation) or are narrowed (stenosis).

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• Heart muscle damage

Areas of the heart muscle that cannot contract normally because of damage due to a heart attack or other conditions

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• Heart size and shape

It shows enlarged heart chambers and thickened heart walls.

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• Blood flow patterns

Doppler and Color imaging show how well the blood is flowing and help to identify blockages or leaks.

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• Presence of fluid

It detects fluid buildup around the heart, as in pericardial effusion

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• Congenital heart defects

It helps identify problems or deformities in the structure that have been present since birth.

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Echocardiograms help to detect

• Aortic aneurysms are bulges in the aorta, the large artery that supplies the body with blood. They have thin walls and can burst.

• Aortic dissection or tear in the aorta is caused by blunt injury and can be life-threatening.

• Blood clots. Excessive blood clotting can block blood flow, a life-threatening condition. The impact depends on the location of the clot in the heart; it can cause a heart attack, a stroke, or a pulmonary embolism in the lungs.

• Congenital heart disease: Failure of the heart to develop properly

• Endocarditis is an infection of the heart valves

• Heart attack damage is caused to the muscles

• In heart failure, the heart muscles are weakened, and the heart cannot pump blood efficiently.

• In cardiomyopathy, the heart muscles get thickened or enlarged

• Pericardial effusion is a buildup of fluid around the heart

• Pericarditis is inflammation of the sac surrounding the heart

• Valvular heart disease is a malfunction of the heart valves

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Limitations of echocardiography

Despite echocardiography being a valuable imaging technique, it has certain limitations. The body structure, inter- and intra-observer variability in measurements, and limitations in visualizing anatomical structures create hindrances in interpreting the echocardiogram.

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Image quality visualization

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1. Patient's body

Obese individuals have poor acoustic windows (openings that permit sound waves to be reflected), which makes it difficult to obtain a clear image.

Inter and intra-observer variability

Different sonographers measure and interpret echocardiograms in different ways.

Echocardiogram

Certain cardiac abnormalities, such as coronary artery anomalies, make it difficult to interpret an echo.

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2. Flow dependence and measurement

Narrowing of the valve (Aortic stenosis)

The flow of blood through the aortic valve helps the doctor determine how narrow the valve is. If the heart is pumping more, as in fever, anemia, or stress, it may overestimate the problem of narrowing. However, if the pumping is diminished, the problem may be underestimated.

Cardiac output

The echo measures how much blood the heart pumps in one beat. Small errors in measuring the heart size affect the accuracy of the results

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3 Limitations in other echocardiograms

Fetal echocardiography may not detect all cardiac abnormalities

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4 Other limitations

Transesophageal echocardiography often requires sedation and can cause injury to the esophagus.

Different ultrasound machines and software can produce varying results

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Conclusion

Echocardiography helps to diagnose heart problems. It evaluates how well a person’s heart pumps blood and if there are any structural defects. It even detects weak heart muscles, blood clots, and improperly functioning heart walls. You may be required to undergo an echocardiogram test if you have symptoms such as shortness of breath, neck swelling, or irregular heartbeat.