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IE can develop in people who already have abnormal blood flow through a heart valve as the result of congenital or acquired heart valve disease​. The abnormal blood flow causes blood clots to form on the surface of the valve. The blood clots make it easier for germs to attach to and infect the valve.

How is Endocarditis Diagnosed?

Your doctor will diagnose IE based on your risk factors, your medical history and signs and symptoms, and test results.

Diagnosis of IE often is based on many factors, rather than a single positive test result, sign, or symptom.

Diagnostic Tests

Blood Tests

Blood cultures are the most important blood tests used to diagnose IE. Blood is drawn several times over a 24-hour period. It's put in special culture bottles that allow bacteria to grow.

Doctors then identify and test the bacteria to see which antibiotics will kill them. Sometimes the blood cultures don't grow any bacteria, even if a person has IE. This is called culture-negative endocarditis, and it requires antibiotic treatment.

Other blood tests also are used to diagnose IE. For example, a complete blood count may be used to check the number of red and white blood cells in your blood. Blood tests also may be used to check your immune system and to check for inflammation.


Echocardiography​ (echo) is a painless test that uses sound waves to create pictures of your heart. Two types of echo are useful in diagnosing IE.

Transthoracic echo. For this painless t​​​est, gel is applied to the skin on your chest. A device called a transducer is moved around on the outside of your chest.

This device sends sound waves called ultrasound through your chest. As the ultrasound waves bounce off your heart, a computer converts them into pictures on a screen.

Your doctor uses the pictures to look for vegetations, areas of infected tissue (such as an abscess), and signs of heart damage.

Because the sound waves have to pass through skin, muscle, tissue, bone, and lungs, the pictures may not have enough detail. Thus, your doctor may recommend transesophageal echo (TEE).

Transephageal echo. For TEE, a much smaller transducer is attached to the end of a long, narrow, flexible tube. The tube is passed down your throat. Before the procedure, you're given medicine to help you relax, and your throat is sprayed with numbing medicine.

The doctor then passes the transducer down your esophagus. Because this passage is right behind the heart, the transducer can get detailed pictures of the heart's structures.


An EKG is a simple, painless test that detects your heart's electrical activity. The test shows how fast your heart is beating, whether your heart rhythm is steady or irregular, and the strength and timing of electrical signals as they pass through your heart.

An EKG typically isn't used to diagnose IE. However, it may be done to see whether IE is affecting your heart's electrical activity.

For this test, soft, sticky patches called electrodes are attached to your chest, arms, and legs. You lie still while the electrodes detect your heart's electrical signals. A machine records these signals on graph paper or shows them on a computer screen. The entire test usually takes about 10 minutes.

Source: National Heart, Lung, and Blood Institute; National Institutes of Health; U.S. Department of Health and Human Services.

Why The Heart Hospital?

The Heart Hospital Baylor Plano provides a comprehensive range of outpatient cardiology diagnostic, treatment, and management services through Outpatient Services, with locations in Plano, Denton, and McKinney. Owned and operated by The Heart Hospital Baylor Plano, Outpatient Services​ offers multidisciplinary clinic-based solutions when you need outpatient cardiology evaluation, treatment, diagnostic imaging services, educational consults and more for complex and/or chronic vascular and heart conditions.

Main phone number: 469.814.3278  469.814.3278 (HEART)

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