An echo, short for echocardiogram, is an ultrasound of your heart. It uses sound waves to create a real-time, moving picture of your heart’s chambers, valves, and blood flow. It’s one of the most commonly ordered heart tests because it’s painless, doesn’t use radiation, and gives doctors a detailed look at how well your heart is pumping.
How an Echo Creates Images of Your Heart
An echocardiogram works the same way sonar does. A small handheld device called a transducer sends high-frequency sound waves (between 2 and 12 MHz, far above what human ears can detect) into your chest. Those waves bounce off your heart’s structures and return to the transducer, which feeds the data to a computer that builds a live image on screen.
The machine calculates two things from each returning wave: how long it took to come back (which reveals how deep the structure is) and how much the wave’s strength changed along the way (which reveals what type of tissue it hit). Dense structures reflect more sound energy and appear brighter on the image, while blood and soft tissue let more sound pass through. Because blood and most soft tissue transmit sound at the same speed, about 1,540 meters per second, the machine can reliably map everything inside the heart using that single assumed speed.
Higher-frequency sound waves produce sharper images but can’t penetrate as deeply into tissue. Lower frequencies reach deeper but sacrifice some detail. The technician adjusts the frequency depending on what part of the heart needs the closest look.
What an Echo Can Detect
An echocardiogram reveals a surprising amount about your heart’s structure and function in a single test. It shows how your heart valves open and close, which makes it especially useful for spotting leaky valves (regurgitation) or valves that have become too narrow (stenosis). It also measures the size of your heart’s four chambers. Conditions like high blood pressure, damaged valves, or heart muscle disease can cause the walls to thicken or the chambers to enlarge, and an echo picks up these changes.
One of the most important numbers that comes from an echo is your ejection fraction: the percentage of blood your left ventricle pumps out with each beat. A normal ejection fraction falls between about 50% and 70%. A number below that range suggests the heart isn’t pumping efficiently, which helps doctors gauge the severity of heart failure or monitor how well a treatment is working.
A Doppler echocardiogram, often performed as part of the same test, measures the speed and direction of blood flow through the heart and its vessels. Color flow imaging layers color onto the picture so the technician can visually spot areas where blood is flowing backward through a leaky valve or moving in an abnormal direction. Together, these techniques give a comprehensive picture of both the heart’s structure and its performance.
Types of Echocardiograms
The two main types are transthoracic (TTE) and transesophageal (TEE). TTE is by far the more common one. It’s noninvasive: a technician presses the transducer against your chest wall while you lie on an exam table, typically on your left side. In some cases you’ll receive a minor injection, but there’s no sedation, no insertion of any instruments, and no recovery time.
TEE is used when a standard echo doesn’t produce clear enough images. Because the esophagus sits directly behind the heart, a small ultrasound probe guided down your throat can capture much sharper detail, especially of the heart’s back-facing structures and valves. TEE is more invasive, requiring sedation and a short recovery period, so it’s reserved for situations where the extra clarity is genuinely needed.
Contrast Echocardiograms and Bubble Studies
Sometimes a standard echo image isn’t quite sharp enough, and your doctor will order a contrast echocardiogram. This involves injecting a contrast agent into a vein, which improves the visibility of the heart’s inner borders on screen. The only FDA-approved use of these specialized contrast agents for cardiac imaging is to better outline the left ventricle, though they’re also used during stress echocardiograms and to assess blood flow through the heart muscle.
A “bubble study” is a simpler version. Agitated saline solution (essentially tiny air bubbles mixed into saltwater) is injected into a vein. These microbubbles show up brightly in the right side of the heart. If bubbles appear on the left side, it signals a hole or abnormal connection between the heart’s chambers, known as a right-to-left shunt. This is one of the quickest ways to detect conditions like a patent foramen ovale, a small opening between the upper chambers that some people are born with.
What to Expect During the Test
A standard transthoracic echo is straightforward. You’ll change into a hospital gown and lie on an exam table, usually on your left side so the heart sits closer to the chest wall. The technician applies a gel to your chest (it helps the sound waves transmit clearly) and moves the transducer to different positions to capture views from multiple angles. You may be asked to breathe in, breathe out, or hold your breath briefly so the technician can get cleaner images.
The test typically takes 30 to 60 minutes. It’s painless, though you might feel some pressure when the transducer is pressed firmly against your ribs. There’s no special preparation for a standard TTE: you can eat, drink, and take your medications as usual beforehand. Results are often available within a day or two, depending on how quickly a cardiologist reviews the images.
Why Your Doctor Might Order One
Echocardiograms are ordered for a wide range of reasons. If you’re experiencing shortness of breath, chest pain, heart palpitations, or unexplained fatigue, an echo can help determine whether a structural heart problem is responsible. It’s also a primary tool for diagnosing and monitoring conditions like heart failure, valve disease, and hypertrophic cardiomyopathy, a condition where the heart muscle becomes abnormally thick.
For people with a family history of certain heart conditions, echocardiographic screening plays an important role even before symptoms appear. Current guidelines recommend that first-degree relatives of someone diagnosed with hypertrophic cardiomyopathy undergo echo screening, with follow-up exams every one to five years depending on age and genetic testing results. Children and adolescents from affected families are screened every one to two years, while adults with no symptoms may only need a repeat echo every three to five years.
An echo is also commonly performed before and after heart surgery, during pregnancy in women with known heart conditions, and as a follow-up tool to track whether treatments are improving heart function over time. Because it’s safe, repeatable, and provides real-time information, it remains one of the most versatile diagnostic tools in cardiology.