Infective EndocarditisInfective endocarditis is an infection that can seriously damage heart valves and cause other seriouscomplications if it is not treated quickly with antibiotics. Surgery to replace, or repair, damagedvalves is also often needed. If you are at increased risk of this infection, do report promptly to yourdoctor any symptoms that you think may be due to infective endocarditis. The earlier the condition isdiagnosed and treated, the better the likely outcome.

What is infective endocarditis?Infective endocarditis is an infection that affects some part of the endocardium. The endocardium is the tissuethat lines the inside of the heart chambers. The infection usually involves one or more heart valves which are partof the endocardium. It is a serious infection that is life-threatening.

How does infective endocarditis occur and progress?Most cases are caused by infection with bacteria. A small number of cases are caused by infection with fungi. Todevelop this infection, you need to have some bacteria or fungi in the bloodstream. The blood usually does notcontain any bacteria or fungi. However, some may get into the blood if you have an infection or wound in anotherpart of the body. In particular, dental and mouth infections are situations where bacteria can quite easily get intothe bloodstream.

People who inject street drugs may also inject bacteria or fungi into their bloodstream if they use dirty orcontaminated needles.

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Most bacteria that get into the bloodstream are killed by the immune system. However, sometimes some bacteriasurvive and settle on a heart valve (particularly if the valve is already damaged in some way), or on anothersection of the endocardium. Once a small focus of infection develops in the endocardium it is difficult for theimmune system to clear it.

In time, small clumps of material called vegetations may develop on infected valves. The vegetations containbacteria or fungi, small blood clots, and other debris from the infection. The vegetations may prevent affectedvalves from opening and closing properly. The infection can also damage affected valves, and may spread toother areas of the endocardium or heart tissue. Fragments of the vegetations may also break off and travel in thebloodstream to other parts of the body.

Who gets infective endocarditis?Endocarditis is uncommon. In the UK it occurs in about 20 in a million people each year. It can occur in anybody,but the risk of developing it is increased in people who have:

Heart valve problems or an artificial heart valve. Heart valves that are already damaged or abnormalare more likely to become infected.Had surgery to a heart valve.Certain congenital heart defects.A heart condition called hypertrophic cardiomyopathy.Had a previous episode of infective endocarditis.Been injecting street drugs such as heroin, with dirty or contaminated needles.A poor immune system - for example, people with AIDS.

What are the symptoms and signs of infective endocarditis?Slowly developing infectionIn many cases the infection develops quite slowly. This is sometimes called subacute bacterial endocarditis(SBE). Symptoms can develop gradually, over weeks or months, and can be vague at first. You tend to feelgenerally unwell and may have general aches and pains, tiredness, and be off your food. A fever (a hightemperature) develops at some stage in most cases. As these first symptoms can be caused by a lot of otherconditions, the cause of the symptoms may not be diagnosed for some time.

Heart murmurs tend to develop. These are sounds that can be heard by a doctor listening to your heart with astethoscope. Murmurs are caused by abnormal flow of blood through faulty or damaged valves. If you alreadyhave a heart murmur from an existing valve problem, the murmur may change or become more intense. A newor changing murmur is often what alerts a doctor to suspect infective endocarditis.

Rapidly developing infectionIn some cases the symptoms develop quite quickly and you can become very unwell over a few days. The speedat which the illness develops partly depends on which bacterium or fungus is causing the infection. Somebacteria are more virulent (aggressive) than others.

What are the possible complications?Complications usually develop if the infection is left untreated, or if treatment is delayed.

Complication in the heartThe infection can damage heart valves. This can lead to serious problems such as heart failure. (See separateleaflet called Heart Failure.) In some cases, the infection spreads and can damage other parts of the heart. Forexample, the infection may spread to affect the conducting (electrical) system of the heart and cause theheartbeat to become erratic. In some cases, an abscess (ball of pus) forms in the heart muscle nearby.

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Complications in other parts of the bodySmall bits may break off from the vegetations on the infected heart valves. These are called infected emboli andget carried in the bloodstream, and lodge in other parts of the body. This can cause various symptoms - forexample:

Small spots may appear under fingernails, in the eyes, or on other parts of the body.Infections may develop in other parts of the body.The spleen may enlarge, as it is the main organ that fights off blood infections.If a larger chunk of vegetation breaks off then it can block the blood flow in a main artery. For example,if it gets stuck in an artery in the brain it can cause a stroke or sudden loss of vision in one eye.

What tests are needed?You will be admitted to hospital if infective endocarditis is suspected. You will have several blood samples takenwhich are tested for bacteria and fungi. If any bacteria are detected in the blood, they are tested against variousantibiotics to find which is the best one to use. (Some bacteria are resistant to some antibiotics. Therefore, thebest antibiotic to use can vary from case to case.)

An ultrasound scan of the heart, called echocardiography, is the most useful test to confirm infectiveendocarditis. This test uses reflected sound waves to create an image of the heart. It can detect vegetations, andlook for damage to heart valves and other heart structures.

Various other tests or scans may be done to find out the extent of the infection, and to assess the damage to theheart or other affected organs.

What is the treatment for infective endocarditis?MedicationAs soon as the condition is suspected you will be given regular doses of antibiotics that are injected directly into avein. Sometimes the type of antibiotics are changed once the results of the blood samples are back and the bestantibiotics to use are found. The course of antibiotics is for at least 2-4 weeks, but it is often longer. The length ofcourse depends on the bacterium causing the infection, and whether there are complications.

If the cause of the infection is found to be a fungus then antifungal medicines will be given.

If you develop complications to the heart or to other parts of the body, you may need other medication - forexample, medicines to counter heart failure, or erratic heartbeats, should they develop.

SurgeryAntibiotic treatment is all that is required in many cases. However, an operation is needed in up to half of caseswhen the infection is more severe. An operation can be life-saving. Operations that may be done include:

Replacing a damaged valve with an artificial valve.Valve repair if the damage is less severe and repair is possible.Drainage of any abscesses (collections of pus) that may develop in the heart muscle or in other partsof the body.

What is the prognosis (outlook)?The outlook is good if the infection is diagnosed and treated early. Many people are cured with a course ofantibiotics. However, it is quite common for the infection to be quite advanced before the diagnosis is made andtreatment is started. Therefore, serious damage to the heart occurs in some cases. Some people die from thecomplications.

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Can infective endocarditis be prevented?If you inject street drugsYour risk of infective endocarditis can be reduced by always using a clean needle and other injecting equipment.

Dental healthGood oral and dental hygiene is also thought to be important. In particular, if you have any condition whichincreases your risk of developing infective endocarditis (see above), then, don't let any dental problems, such asa dental abscess or gum disease, go untreated. These dental conditions increase the chance of bacteria gettinginto the bloodstream.

If you have dental and surgical proceduresUntil early 2008, it had been usual medical practice to advise people with an increased risk of developing infectiveendocarditis to take a short course of antibiotics (antibiotic cover) during certain procedures. These included:various dental procedures; looking into the stomach (endoscopy); looking into the bowel (colonoscopy); lookinginto the bladder (cystoscopy). The logic was that these procedures might push some bacteria into thebloodstream and that antibiotic cover would kill bacteria that get into the blood before they settle on theendocardium or heart valves.

However, in March 2008 the National Institute for Health and Clinical Excellence (NICE) published new guidanceon the use of antibiotic prophylaxis (antibiotic cover) against infective endocarditis. This recommended an end tothe practice of prescribing antibiotics for at-risk patients during dental and other procedures. NICE recommendsthat you should now only be offered antibiotic cover if the procedure is at a site where there is already asuspected infection. The reason for this change in practice is because NICE found that research studies do notsupport the use of antibiotics to prevent infective endocarditis during dental or other procedures. Also, takingantibiotics carries its own risk (such as side-effects, and sometimes serious reactions to antibiotics).

However, this national NICE guideline is controversial. It has caused a lot of debate, especially from somecardiologists (heart doctors) and dentists. See the references below for details of some articles that deal with thiscontroversy. For example, guidelines produced by the European Society of Cardiology in 2009 proposed thatantibiotic prophylaxis be given to people with the highest risk of developing infective endocarditis if they undergohigh-risk dental procedures. (Details of what is considered high risk is in the guideline - cited below and availableonline). Your own doctor or dentist will advise for your own particular circumstance.

A final pointIf you have an increased risk of developing infective endocarditis, do report promptly to your doctor anysymptoms that you think may be due to infective endocarditis. The earlier the condition is diagnosed and treated,the better the likely outcome.

Further help & informationBritish Heart FoundationGreater London House, 180 Hampstead Road, London, NW1 7AW

Tel: (Heart Helpline) 0300 330 3311, (Admin) 020 7554 0000

Web: www.bhf.org.uk

Further reading & referencesProphylaxis against infective endocarditis: Antimicrobial prophylaxis against infective endocarditis in adults and childrenundergoing interventional procedures; NICE Clinical Guideline (March 2008)Guidelines for the diagnosis and antibiotic treatment of endocarditis in adults, British Society for AntimicrobialChemotherapy (2012)2008 Focused Update Incorporated Into the ACC/AHA 2006 Guidelines for the Management of Patients With Valvular HeartDisease; American College of Cardiology/American Heart Association Task Force on Practice GuidelinesKang DH, Kim YJ, Kim SH, et al; Early surgery versus conventional treatment for infective endocarditis. N Engl J Med. 2012Jun 28;366(26):2466-73. doi: 10.1056/NEJMoa1112843.

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Brusch JL et al; Infective Endocarditis, Medscape, Sep 2012Guidelines on Prevention, Diagnosis and Treatment of Infective Endocarditis ; European Society of Cardiology (2009)

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medicalconditions. EMIS has used all reasonable care in compiling the information but make no warranty as to itsaccuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions.For details see our conditions.

Original Author:Dr Tim Kenny

Current Version:Dr Colin Tidy

Peer Reviewer:Dr Hannah Gronow

Document ID:4680 (v44)

Last Checked:20/11/2012

Next Review:20/11/2015

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