An echo, short for echocardiogram, is an ultrasound of your heart. It uses sound waves to create real-time moving images of your heart’s chambers, valves, walls, and blood vessels, letting doctors see how well your heart is pumping and whether any structures look abnormal. A standard echo takes 40 to 60 minutes, is painless, and doesn’t use radiation.
How an Echo Creates Images of Your Heart
An echo works on the same principle as all ultrasound: a handheld device called a transducer sends pulses of high-frequency sound waves into your chest. These waves travel through tissue at about 1,540 meters per second. When they hit a boundary between two types of tissue (say, muscle and blood), some of the sound bounces back. The transducer picks up these reflected waves and a computer translates their strength, direction, and timing into a picture.
Dense structures like bone reflect more sound and appear bright white on the screen. Fluid-filled spaces reflect almost no sound and appear black. Heart muscle, valves, and blood all fall somewhere in between, creating the contrast that makes different parts of your heart visible. The machine refreshes these images at least 15 times per second, producing a live video of your heart beating in real time.
What an Echo Can Measure
One of the most important numbers from an echo is your ejection fraction, which tells you what percentage of blood your left ventricle pumps out with each beat. A normal ejection fraction falls between about 50% and 70%. A lower number can signal heart failure or weakened heart muscle.
Beyond pumping strength, an echo shows the size and thickness of your heart’s chambers, how well your valves open and close, the direction and speed of blood flow, and whether fluid has collected around the heart. For valve problems specifically, doctors can measure the area of an opening (a normal mitral valve opening is 4 to 6 square centimeters, while anything under 1.5 square centimeters indicates severe narrowing) and detect abnormal backflow of blood through a leaky valve. These measurements help determine whether a valve problem needs monitoring or intervention.
How an Echo Differs From an EKG
An EKG (electrocardiogram) records the electrical signals that trigger each heartbeat. It’s excellent for detecting rhythm problems, but it shows almost nothing about the physical structure of your heart. An echo is the opposite: it directly images the heart’s anatomy and blood flow in motion. Research comparing the two found that EKG measurements are unreliable for tracking changes in heart muscle thickness over time, while echo remains the reference method for detecting conditions like thickening of the left ventricle wall. In short, an EKG tells you about your heart’s electrical wiring. An echo tells you about the plumbing and the pump itself.
Types of Echocardiograms
Transthoracic Echo (TTE)
This is the standard, most common type. You undress from the waist up, put on a hospital gown, and lie on an exam table (usually on your left side). A technician places small electrode stickers on your chest to monitor your heart rhythm, then presses the transducer against your chest wall using a gel that helps the sound waves travel. You may be asked to hold your breath or shift positions at certain points so the technician can get clearer images. It’s completely painless.
Transesophageal Echo (TEE)
When a standard echo can’t capture enough detail, doctors may use a TEE instead. This involves threading a thin, flexible tube with a tiny transducer on its tip down your throat and into your esophagus, which sits right behind the heart. Because the probe is so close to the heart with no ribs or lung tissue in the way, the images are much more detailed. A TEE is particularly useful for finding blood clots, evaluating prosthetic heart valves, diagnosing tears in the aorta, and guiding surgeons during valve procedures.
Before a TEE, your throat is numbed with a spray and you receive sedation through an IV. You lie on your left side, and the lubricated tube is guided down your throat (you may be asked to swallow to help it along). The whole procedure is generally well tolerated, though you may have a mild sore throat for a day or two afterward.
Stress Echo
A stress echo combines a standard echo with exercise or medication to see how your heart performs under strain. Typically, images are taken at rest, then you walk or run on a treadmill, and images are taken again immediately after. If you can’t exercise, a medication can be given through an IV to make your heart beat faster and harder, mimicking the effect of physical activity. You should avoid caffeine for 24 hours before the test and follow your doctor’s guidance about any medications you’re taking that day. Some people experience chest discomfort or shortness of breath during the exercise portion, which is expected and monitored.
Fetal Echo
A fetal echo is performed during pregnancy, typically between 18 and 24 weeks, to check a developing baby’s heart. It’s done the same way as a standard pregnancy ultrasound, with a transducer on the mother’s abdomen. Doctors order it when there’s a family history of heart defects, when a routine ultrasound picks up an abnormal heart rhythm, or when the mother has conditions like diabetes, lupus, or rubella infection during the first trimester. Certain medications, including some epilepsy drugs and prescription acne treatments, can also affect fetal heart development and prompt the referral.
3D Echocardiography
Traditional echos produce flat, two-dimensional images. Newer 3D echo technology captures a full volume of the heart, which doctors can then rotate and slice from any angle. Professional cardiology guidelines now recommend 3D imaging over 2D for measuring the size of the heart’s pumping chambers and ejection fraction, because it produces more accurate and consistent results. 3D is also preferred for evaluating mitral and aortic valve disease and for guiding catheter-based valve procedures in real time. Not every facility has 3D capability, but it’s increasingly standard in cardiac imaging centers.
Common Reasons Doctors Order an Echo
An echo is typically the first imaging test ordered when a doctor suspects a structural heart problem. Common triggers include symptoms of heart failure (shortness of breath, leg swelling, fatigue), unexplained palpitations or fainting episodes, a new heart murmur heard through a stethoscope, high blood pressure with suspected thickening of the heart wall, and follow-up after heart surgery or an infection that may have reached the heart valves. It’s also used routinely to monitor known conditions over time, tracking whether a valve leak is stable or worsening, or whether heart failure treatment is improving pump function.
Because an echo is noninvasive, repeatable, and free of radiation, it can be done as often as needed without cumulative risk. For many heart conditions, it’s the single most informative test available.