Infective Endocarditis

To develop this infection you need to have some bacteria or fungi in the bloodstream. This can be from an infection or wound in another part of the body.  A small number of cases are caused by infection with fungi although most cases are caused by infection with bacteria.

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

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

Signs and symptoms

• Slowly developing infection
• You tend to feel generally unwell and may have aches and pains, tiredness, and be off your food.
• A fever (a high temperature) develops at some stage in most cases.

As these first symptoms can be caused by a lot of other conditions, the cause of the symptoms may not be diagnosed for some time.

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

How is infective endocarditis diagnosed?

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

An ultrasound scan of the heart called echocardiography is the most useful test to confirm infective endocarditis. It can detect vegetations, and look 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 the heart or other affected organs.

How is Infective Endocarditis treated?

Medication

As soon as the condition is suspected you will be given regular doses of antibiotics that are injected directly into a vein. Sometimes the type of the antibiotics are changed once the results of the blood samples are back and the best antibiotics to use are found. The course of antibiotics is for at least 2-4 weeks, but it is often longer. The length of course 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 anti-fungal drugs will be given.

If you develop complications to the heart or other parts of the body you may need other medication. For example, drugs to counter heart failure, or erratic heart beats, should they develop.

Surgery

Antibiotic treatment is all that is required in most cases. However, an operation is needed in about 1 in 4 cases where the infection is more severe. An operation can be life-saving.

Operations that may be performed 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 other parts of the body.

Dental Health

Good oral and dental hygiene is also thought to be important. In particular, if you have any condition which increases your risk of developing infective endocarditis, then, don't let any dental problems such as a dental abscess or gum disease go untreated. These dental conditions increase the chance of bacteria getting into the bloodstream.

Until early 2008, it had been usual medical practice to advise people with an increased risk of developing infective endocarditis 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) 
• Looking into the bladder (cystoscopy).

The logic was that these procedures might 'push' some bacteria into the bloodstream and that antibiotic cover would kill bacteria that get into the blood before they settle on the endocardium or heart valves.

Cardiac conditions for which endocarditis prophylaxis is recommended:

• Prosthetic heart valves (biological or mechanical)
• Rheumatic valvular heart disease
• Previous endocarditis
• Unrepaired cyanotic congential heart disease (includes palliative shunts and conduits)
• Surgical or catheter repair of congenital heart disease within 6 months of repair procedure.

(New Zealand Guideline for Prevention of Infective Endocarditis Associated with dental and other medical interventions).

Your own doctor or dentist will advise for your own particular circumstance.