It is also known as infective endocarditis (IE), bacterial endocarditis (BE), infectious endocarditis, and fungal endocarditis.
An infection of the endocardium causes endocarditis. The infection is normally caused by streptococcal or staphylococcal bacteria. Rarely, it can be caused by fungi or other infectious micro-organisms.
It is twice as common in men as in women. In the United States, over 25 percent of cases affect people aged 60 years or above.
Studies suggest that endocarditis affects at least 4 in every 100,000 people each year, and that the number is increasing.
Contents of this article:
Causes and risk factors
Endocarditis is an inflammation that affects the heart.
Endocarditis can happen when bacteria or fungi enter the body because of an infection, or when normally harmless bacteria that live in the mouth, upper respiratory tract, or other parts of the body attack the heart tissue.
Normally, the immune system can destroy these unwanted micro-organisms, but any damage to the heart valves can allow them to attach themselves to the heart and to multiply.
Clumps of bacteria and cells, or vegetation, form on the heart valves. These clumps make it harder for the heart to work properly.
They can cause abscesses on the valves and the heart muscle, damage tissue, and lead to abnormalities in electrical conduction.
Sometimes, a clump can break off and spread to other areas, such as the kidneys, lungs, and brain.
A dental problem or procedure that results in an infection can trigger it. Poor health in the teeth or gums increases the risk of endocarditis, as this makes it easier for the bacteria to get in. Good dental hygiene helps prevent heart infection.
Other surgical procedures can allow bacteria to enter, including tests to examine the digestive tract, for example, a colonoscopy. Procedures that affect the breathing tract, the urinary tract, including kidneys, bladder, and urethra, the skin, the bones and the muscles, are also risk factors.
A heart defect can increase the risk of developing endocarditis if bacteria enter the body. This can include a defect from birth, an abnormal heart valve or damaged heart tissue. People with an artificial heart valve have a higher risk.
A bacterial infection in another part of the body, for example, a skin sore or a gum disease, can lead to the spread of bacteria. Injecting drugs with unclean needles is a risk factor. Anyone who develops sepsis is at risk of endocarditis.
A candida fungal infection can cause endocarditis.
Inflammatory bowel disease (IBD) or any intestinal disorders may also increase the risk, but the risk of a person with IBD developing endocarditis is still low.
Surgical or medical tools used in treatment, such as a urinary catheter or long-term intravenous medication can increase the risk.
A person may be at higher risk of developing endocarditis if they:
- have an existing heart condition or disease
- have had heart replacement surgery or received an artificial heart valve
- have had a disease, such as rheumatic fever, which damaged at a heart valve
- have received a pacemaker
- have regularly received drugs intravenously
- are convalescing after a serious bacterial illness, such as meningitis or pneumonia
- have an immune system that is chronically suppressed, for example, because of diabetes or HIV, or if they have cancer or are receiving chemotherapy
As people age, their heart valves degenerate, increasing the risk of endocarditis.
Signs and symptoms
Symptoms vary between individuals, and individual symptoms can change over time.
In sub-acute endocarditis, symptoms appear slowly over several weeks, and possibly several months.
Rarely, the infection develops rapidly, and symptoms appear abruptly. This is called acute endocarditis, and symptoms tend to be more severe.
Endocarditis is difficult to diagnose. Symptoms may vary in severity, depending on the type of bacteria or fungi causing the infection. Patients with underlying heart problems tend to have more severe symptoms.
Symptoms may include:
Symptoms include fever, chest pain, and fatigue.
- A high temperature, or fever
- A new or different heart murmur
- Muscle pain
- Bleeding under the fingernails or toenails
- Broken blood vessels in the eyes or skin
- Chest pain
- Shortness of breath, or panting
- Small painful, red or purple lumps, or nodules, on the fingers, toes, or both
- Small, painless, flat spots on the sole of the feet or palms of the hands
- Small spots from broken blood vessels under the nails, on the whites of the eyes, on the chest, in the roof of the mouth and inside the cheeks
- Sweating, including night sweats
- Swelling of the limbs or abdomen
- Blood in the urine
- Weakness, tiredness, and fatigue
- Unexpected weight loss
These symptoms may not be specific to endocarditis.
Diagnosis and treatment
The physician will ask about the patient's medical history and identify any possible heart problems and recent medical procedures or tests, such as operations, biopsies or endoscopies.
They will also check for fever, nodules, and other signs and symptoms, such as a heart murmur, or an altered heart murmur if the patient already had one.
A series of tests may be used to confirm endocarditis. The symptoms of endocarditis may overlap with those of other conditions, so these may need to be ruled out first. This may take some time.
The following tests may be done:
- Blood culture test: to check for bacteria or fungi in the patient's blood. If any are found, they are usually tested with some antibiotics to find out which treatment is best.
- Erythrocyte sedimentation rate (ESR): this test looks at how fast the patient's blood falls to the bottom of a test tube full of liquid. The faster the cells fall, the more likely it is that there is an inflammatory condition, such as endocarditis. Most patients with endocarditis have high ESR. The blood reaches the bottom of the liquid faster than normal.
- Echocardiogram: sound waves produce images of the parts of the heart, including muscle, valves, and chambers. This shows the structure and workings of the heart in more detail. An echocardiogram can reveal clumps of bacteria and cells, known as vegetations, and infected or damaged heart tissue.
A CT scan can help to pinpoint any abscesses in the heart.
The main course of treatment is antibiotics, but sometimes surgery is necessary.
Most patients with endocarditis will receive antibiotics. These will be given intravenously, through a drip, so the patient will need to stay in the hospital. Regular blood tests will monitor the effectiveness of the medication.
Patients can usually go home when their temperature returns to normal and symptoms have subsided, but most will continue to take antibiotics at home.
The patient should keep in touch with their doctor to make sure the treatment is effective, and that side effects are not preventing recovery.
The most commonly used antibiotics are penicillin and gentamycin. Patients who are allergic to penicillin may be given vancomycin. Antibiotic treatment normally lasts from 2 to 6 weeks, depending on the severity of the infection, among other things.
If the endocarditis has damaged the heart, surgery may be necessary.
Heart surgery may be necessary if there is damage to the heart valves.
Surgery is recommended if:
- the heart valve is so damaged that it does not close tightly enough, and regurgitation occurs, where the blood flows back into the heart
- the infection continues because the patient does not respond to antibiotic or antifungal medication
- large clumps of bacteria and cells, or vegetations, are attached to a heart valve
Surgery may repair a heart defect or damaged heart valves, replace them with artificial ones, or drain the abscesses that have developed within the heart muscle.
Complications, outlook, and prevention
Complications are more likely if endocarditis is left untreated, or if treatment is delayed.
- Damaged heart valves increase the risk of heart failure.
- If heart rhythms are affected, arrhythmia, or irregular heartbeat, may occur.
- The infection can spread within the heart and to other organs, such as the kidneys, lungs, and brain.
- If vegetations break off, they can travel through the bloodstream to other parts of the body and cause infections and abscesses elsewhere.
Vegetation that finds its way to the brain and gets stuck there can cause stroke or blindness. A large vegetation can get stuck in an artery and block blood flow.
Outlook and prevention
Untreated endocarditis is always fatal, but with early treatment, involving an aggressive use of antibiotics, most patients survive.
However, it can still be fatal in older people, patients with an underlying condition, and those whose infection involves a resistant type of bacteria.
The National Heart, Lung and Blood Institute (NHLBI) encourage those who are at risk of endocarditis to have regular dental checkups and to brush and floss their teeth regularly.
Since 2007, the American Heart Association has recommended that those with a high risk of endocarditis should receive antibiotics before undergoing dental procedures.