An echocardiogram shows the structure, movement, and blood flow of your heart in real time. It reveals the size and shape of all four chambers, how well your heart muscle contracts, whether your valves open and close properly, and how blood moves through the heart with each beat. It’s the most common test used to evaluate heart function, and it can detect everything from weakened heart muscle to blood clots to congenital defects.
Heart Chambers and Valves
Your heart has four chambers: two upper chambers (the right and left atria) and two lower chambers (the right and left ventricles). An echocardiogram shows all four, along with the four valves that control blood flow between them. The test also captures surrounding structures like the aorta (the large artery leaving the heart), the pericardium (the protective sac around the heart), and the inferior vena cava (the large vein returning blood to the heart).
The technician captures several different “views” by angling the ultrasound probe at different positions on your chest. One view might show the left ventricle, left atrium, and aorta side by side. Another shows all four chambers at once, making it easy to compare their sizes. A cross-sectional view cuts through the heart like slicing a loaf of bread, letting the cardiologist examine the valve leaflets and the thickness of the heart muscle walls from a different angle. Together, these views build a comprehensive picture of your heart’s anatomy.
How Well Your Heart Pumps
One of the most important numbers from an echocardiogram is your ejection fraction, which measures the percentage of blood your left ventricle pushes out with each beat. A normal ejection fraction is 50% to 70%, though the exact range differs slightly between men (52% to 72%) and women (54% to 74%).
An ejection fraction of 40% to 49% is considered mildly reduced, meaning your heart is pumping slightly below normal. Below 39% qualifies as heart failure with reduced ejection fraction, a condition where the heart can no longer meet the body’s demands efficiently. This single number gives your doctor a quick, reliable gauge of overall heart strength and often determines the next steps in treatment.
Valve Problems: Narrowing and Leaking
Echocardiograms are the primary tool for diagnosing valve disease, which comes in two main forms. Stenosis means a valve has narrowed and doesn’t open fully, forcing the heart to work harder to push blood through. Regurgitation means a valve doesn’t close completely, allowing blood to leak backward.
The test detects both problems using Doppler technology, which measures the speed and direction of blood flow. When blood squeezes through a narrowed valve, it accelerates, much like water through a pinched garden hose. The echocardiogram measures that speed and converts it into a pressure reading. For example, blood flowing across a severely narrowed aortic valve reaches speeds of 4 meters per second or higher, corresponding to a pressure buildup of at least 40 mmHg. A normal valve creates almost no pressure difference at all.
For leaking valves, the test measures how far back the jet of leaking blood extends and how much volume escapes with each heartbeat. A severely leaking mitral valve, for instance, allows 60 milliliters or more of blood to flow backward into the upper chamber per beat. The echocardiogram grades the severity as mild, moderate, or severe, which directly influences whether you need monitoring, medication, or surgery.
Blood Flow and Pressure Estimates
Doppler ultrasound works by detecting shifts in sound wave frequency as they bounce off moving red blood cells. Blood flowing toward the probe shifts the frequency up; blood flowing away shifts it down. This lets the echocardiogram map the speed and direction of blood throughout the heart in real time, displayed as color-coded images where red typically indicates flow toward the probe and blue indicates flow away.
Beyond valve assessment, these flow measurements help estimate pressures inside the heart and lungs. Elevated pressure in the lung arteries, for example, can be estimated by measuring the speed of a small jet of blood leaking back through the tricuspid valve. The cardiologist can also assess how the heart fills during relaxation, which helps identify a type of heart failure where the heart pumps normally but stiffens and doesn’t fill properly.
Wall Motion and Heart Muscle Damage
An echocardiogram shows how each segment of the heart muscle contracts. In a healthy heart, all walls squeeze inward symmetrically with each beat. After a heart attack, the damaged section stops moving normally, and this is clearly visible on the screen.
There are distinct patterns the test can identify. Hypokinesis means a section moves weakly. Akinesis means it doesn’t contract at all. Dyskinesis means it actually bulges outward when the rest of the heart squeezes, a sign of significant scarring. Wall thinning in these areas confirms that muscle tissue has been replaced by scar. These regional wall motion abnormalities are important because persistent damage after a heart attack increases the risk of heart failure and further complications. If the heart muscle recovers normal motion after treatment, the outlook is significantly better than when these abnormalities persist.
Conditions an Echocardiogram Can Diagnose
The range of conditions detectable on an echocardiogram is broad:
- Cardiomyopathy: diseases of the heart muscle that cause it to enlarge, thicken, or stiffen
- Valve disease: narrowing or leaking of any of the four heart valves
- Congenital heart defects: structural problems present from birth, such as holes between chambers
- Pericardial effusion and pericarditis: fluid buildup or inflammation in the sac surrounding the heart
- Blood clots: clots forming inside the heart chambers, which can cause stroke if they travel to the brain
- Heart tumors: growths inside the heart, whether cancerous or benign
- Infective endocarditis: a serious infection of the heart valves
- Aortic aneurysm: a dangerous bulge in the aorta within the chest
Types of Echocardiograms
The standard echocardiogram is a transthoracic echo, where the technician applies gel to your chest and moves a handheld probe across it. It’s completely noninvasive, requires no fasting or sedation, and typically takes 30 to 60 minutes. This is the version most people get, and it provides excellent images for the majority of clinical questions.
A transesophageal echo takes a different approach. After sedation, a thin ultrasound probe is guided through your mouth and into your esophagus, which sits directly behind the heart. Because the sound waves don’t have to pass through skin, muscle, ribs, or lung tissue, the images are significantly sharper. This version is used when the standard test doesn’t provide clear enough pictures, often due to obesity or lung disease, or when the cardiologist needs a closer look at specific structures like the mitral valve or the left atrial appendage (a common site for blood clots).
Stress echocardiograms combine the test with exercise or medication that makes your heart beat faster. By comparing images at rest and under stress, the cardiologist can spot areas of the heart that don’t get enough blood flow during exertion, a hallmark of coronary artery disease. One limitation is that image quality can decrease during exercise, particularly at high heart rates when the filling phases of the heartbeat start to overlap.
What an Echo Can and Cannot Tell You
Echocardiography is highly specific, meaning that when it identifies a problem, the finding is usually reliable. Its sensitivity, however, is more limited for certain conditions. It excels at detecting structural problems: enlarged chambers, thickened walls, malfunctioning valves, and fluid around the heart. It provides good estimates of pressures and blood flow. But it can miss subtler forms of heart failure, particularly the type where the heart pumps normally but doesn’t relax properly. In those cases, specialized measurements or additional testing may be needed.
The test also cannot directly visualize the coronary arteries. A stress echo can suggest blocked arteries by revealing wall motion problems that appear only during exercise, but to see the arteries themselves, you’d need a different test like a coronary angiogram or CT scan. Despite these limits, the echocardiogram remains the single most versatile cardiac imaging tool, providing more information about heart function in one sitting than almost any other noninvasive test.