Echocardiogram vs EKG

The short answer

These two tests answer different questions, so one does not replace the other. An EKG records the heart's electrical signals through stickers on your chest, arms, and legs. It is also written ECG, or electrocardiogram. The test takes about five minutes. It shows rhythm problems, signs of a past heart attack, and patterns of electrical strain. An echocardiogram is an ultrasound picture of the heart in motion. It shows chamber size, valve function, and the thickness of the muscle walls. It also shows fluid around the heart, and how strongly the heart squeezes. Does your cardiologist want to know how your heart behaves electrically? The EKG answers that. Is the question how your heart is built and how well it pumps? The echocardiogram answers that. Most heart workups start with an EKG, because it is quick and low cost. An echocardiogram is added when structure or pump function is in question.

How they differ at a glance

Electrocardiogram in detail

An electrocardiogram captures the electrical wave that runs through the heart with every beat. Electrodes on the skin sense that wave from twelve angles. That is why it is often called a twelve lead EKG.

Its strength is speed and breadth. Within seconds a cardiologist can see whether the rhythm is regular. The tracing shows whether the upper and lower chambers are talking to each other normally. It can suggest that an artery is blocked right now. It can also show the scar left by an old heart attack. In a chest pain workup it is the first test done, because it sorts emergencies from everything else. The American Heart Association describes this role in detail.

Its limit is the snapshot. An EKG records perhaps ten seconds. If your palpitations come twice a week, the tracing will very likely be normal. A wearable monitor is the answer then. Our Holter vs event monitor page and the arrhythmias page cover those devices.

An EKG also says little about valves. A leaking valve can produce a perfectly normal tracing.

Echocardiogram in detail

An echocardiogram uses sound waves rather than radiation. We do the standard version in our offices, transthoracic echocardiography. The probe simply rests on the outside of the chest.

It produces a live moving image. Doppler settings add color and sound to show the direction and speed of blood flow. That is how valve leaks and narrowings are graded. The most quoted result is the ejection fraction. It is the share of blood the left ventricle pushes out with each beat. A normal value sits roughly between 55 and 70 percent. The American Heart Association echocardiogram page explains what the numbers mean.

The scan also finds fluid around the heart and clots inside the chambers. It finds thickened muscle from years of high blood pressure, and heart defects present from birth.

Its limit is that it does not read rhythm. It also depends on picture quality. That quality can be poor in patients with lung disease or a larger body. Another imaging test may be needed then.

How Dr. Nanavati decides which is right for you

The symptom drives the test. Palpitations, fainting, or an irregular pulse point to the electrical side, so the EKG comes first. Shortness of breath, ankle swelling, a murmur heard on exam, or known valve disease point to ultrasound.

Order matters more than choice. Almost every new heart patient gets an EKG, because it is fast and it changes decisions. The echocardiogram follows when your history, your exam, or the EKG itself raises a question about structure.

An abnormal EKG often triggers an echocardiogram. Examples are voltage that suggests thick walls, a pattern of past heart attack, or a new bundle branch block. Each one justifies imaging the muscle directly.

Neither test measures blood flow under stress. If chest pain comes on with effort, a stress study is the right next step. Our treadmill vs nuclear stress test page explains those options.

Both tests are safe, painless, and free of radiation. So the order usually comes down to cost and to what each test can tell us, not to risk. General background on heart testing is available from MedlinePlus and the National Heart, Lung, and Blood Institute.

Questions to ask your cardiologist

• Which specific question are we trying to answer with this test?
• Will an EKG alone be enough, or should we image the heart structure too?
• What is my ejection fraction, and is it in the normal range?
• If my symptoms come and go, would a longer rhythm monitor be more useful?
• Do my results need to be repeated, and if so, how often?
• Does anything in these results change my medicines?

Talk it through with a cardiologist

Dr. Vimal Nanavati, MD, FACC is board certified in cardiology and interventional cardiology, with 32 years in practice. He founded HeartCare4life in 1997.

EKGs, echocardiograms, stress testing, vascular ultrasound, and Holter monitoring are all done in the office. Results are reviewed with you promptly.

Request an appointment online, call South San Diego at (619) 585-0476 or Redding at (530) 433-5427, see all locations including North San Diego, read about Dr. Nanavati, or browse our FAQs.