Diagnosis of Endocarditis

The diagnosis of endocarditis may be suggested by the patient's symptoms and by physical examination. Unfortunately, the symptoms are often nonspecific and may only suggest the condition.

In most cases, patients with endocarditis experience fever. During physical examination, the physician often discovers a new heart murmur. Heart murmurs are sounds heard with a stethoscope that occur when there is abnormal, turbulent blood flow in the heart. The development of a leaky heart valve caused by infection-induced damage to the heart valve can result in this turbulent blood flow.

Bacteria in the bloodstream are highly suggestive of endocarditis and if endocarditis is suspected, multiple sets of blood cultures usually are obtained. Approximately a tablespoon of blood is withdrawn from a vein and mixed with a special nutrient-containing solution. This mixture is then observed to determine if any bacteria grow in it. If bacteria are present in the sampled blood, growth is usually observed within 1 or 2 days.

Most patients suspected of having endocarditis undergo an echocardiogram (cardiac echo). During this noninvasive procedure, a microphone-like device (transducer) is used to transmit and receive special ultrasound waves that travel through the chest wall to the heart and then are reflected back to the transducer. These reflected sound waves are translated into video images of the walls and valves of the heart.

During the echocardiogram, images of the valves are obtained to detect signs of infection. Physicians may refer to heart valve infections as vegetations. Echocardiogram is able to detect vegetations on infected heart valves in about 45–75 percent of cases. In some cases, images obtained by echocardiogram are not clear or the vegetations are too small to be detected. Therefore, a negative echocardiogram does not rule out a diagnosis of endocarditis.

In some cases of suspected endocarditis, a special type of echocardiogram called a transesophageal echo (TEE) may be performed. A transesophageal echo uses a long tube with a special microphone-like device mounted on one end. The tube is passed through the mouth and throat and then down the esophagus (organ that connects the throat to the stomach, located directly behind the heart). This allows the imaging part of the transesophageal echo to be placed in close proximity to the heart and enables the doctor to obtain high-quality images of the heart and the heart valves.

This procedure is able to detect more than 90 percent of heart valve infections. During TEE, the mouth and throat usually are sprayed with numbing medicine and patients are given a sedative to help them relax.

Treatment for Endocarditis

Primary treatment for endocarditis involves an intensive course of antibiotics (e.g., penicillin, nafcillin [Nafcil, Unipen], gentamicin [Gentacidin, Garamycin]), usually for at least 4 to 6 weeks. For much, if not all of this time, the antibiotics are administered intravenously (i.e., through a vein). To increase the chances of successfully treating the infection, a combination of antibiotics is often used.

Several additional blood cultures usually are obtained during antibiotic therapy to make sure that bacteria are not continuing to grow in the bloodstream.

Sometimes, the infection is not controlled with antibiotics, and the bacteria continue to grow on the infected heart valve, and possibly in the blood. If this occurs, open heart surgery may be necessary to remove and replace the infected heart valve.

Endocarditis Prevention

Some cases of endocarditis cannot be prevented. High-risk patients may be given antibiotics before dental or surgical procedures, body piercing, or tattooing to reduce the risk (called endocarditis prophylaxis). Maintaining good oral hygiene by brushing and flossing regularly and by having periodic dental examinations also may help reduce the risk for endocarditis.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 30 Jun 2000

Last Modified: 14 Sep 2015