Tuesday, December 16, 2008

Bacterial Endocarditis

(Infective Endocarditis)
Bacterial endocarditis is an infection of the endocardium. This is a thin membrane that covers the inner surface of the heart muscles and valves. Infection occurs when bacteria attach to the endocardium and grow.
Bacterial endocarditis is most common when the heart or valves have already been damaged. It can be life-threatening. It can permanently impair the heart valves. This can lead to serious health problems, including congestive heart failure.
Bacterial Endocarditis

Bacteria enter the bloodstream and travel to the heart where, under certain conditions, they may attach to the endocardium. Bacteria may enter due to an infection elsewhere in the body or during an activity that repeatedly breaks the skin or mucous membranes. This activity can be dental work, surgery, or intravenous (IV) drug use. Only certain bacteria cause endocarditis. The most common are: streptococci, staphylococci, and enterococci.
If the heart is normal, with no valve defects or scarring, endocarditis rarely results. But if the heart has certain abnormalities in which blood flow is obstructed or abnormally pooled (ie, cardiac arrhythmias or valvular defects), the bacteria can lodge there and cause an infection. The infection causes growths on the valves or other areas of the heart. Pieces of these growths can break off, travel to other parts of the body, and cause serious complications.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
The following conditions put you at greater risk during certain procedures:
• Heart valve scarring, due to rheumatic fever or other conditions
• Artificial heart valve
• Congenital heart defect
• Cardiomyopathy
• Prior episode of endocarditis
• Mitral valve prolapse, with significant regurgitation (abnormal backflow of blood)
If you have one of the conditions listed above, a procedure causing bacteria to enter the bloodstream increases your risk of endocarditis. This includes:
• Intravenous drug use; risk is extremely high when needles are shared
• Any dental procedure, even cleanings
• Removal of tonsils or adenoids, and other procedures involving the ears, nose, and throat
• Bronchoscopy (viewing the airways though a thin, lighted tube)
• Surgery on the gastrointestinal or urinary tracks, including the gallbladder and prostate
Symptoms vary from mild to severe, depending on:
• The bacteria causing the infection
• The amount of bacteria in the bloodstream
• The extent of structural heart defects
• Your body's ability to fight infection
• Your overall health
Symptoms usually begin within two weeks of the bacteria entering the bloodstream. They include:
• Fever
• Chills
• Fatigue
• Weakness
• Malaise
• Unexplained weight loss
• Poor appetite
• Muscle aches
• Joint pain
• Coughing
• Shortness of breath
• Little red dots on the skin, inside the mouth, and/or under the nails
• Bumps on the fingers and toes
Note: The first symptom may be a stroke or other complication from a piece of the infected heart growth breaking off and traveling to another organ.
The doctor will ask about your symptoms and medical history, and perform a physical exam. The doctor will listen to your heart for a murmur.
Tests may include:
• Blood cultures to test for the presence of bacteria
• Blood tests indicating signs of infections and complications related to endocarditis
• CT scan – a type of x-ray that uses a computer to make pictures of the inside of the chest
• Electrocardiogram (ECG, EKG) – a test that records the heart's activity by measuring electrical currents through the heart muscle
• Echocardiogram – a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart. The standard echocardiogram is done through the chest wall. Another type of echocardiogram might be indicated called transesophageal echocardiogram, in which the ultrasound is passed through your mouth into the esophageus. This allows doctors to visualize heart valves better.
Treatment aims to eliminate the infection from the blood and endocardium.
Antibiotics are given through a vein. You must be admitted to the hospital to begin this therapy. Antibiotic therapy may last for 4-6 weeks.
If the antibiotics fail to remove the bacteria or the infection returns, surgery may be considered. Patients with a failing heart due to a malfunctioning valve or other heart defect may need surgery to correct the problem. Surgery also may be needed if an artificial valve becomes unstable or an abscess develops.
The best way to prevent endocarditis is to avoid the use of illegal IV drugs. Certain heart conditions (eg, prosthetic heart valves, prior history of endocarditis, etc.) may increase your risk of endocarditis. The American Heart Association recommends that patients with high and moderate risk for endocarditis take antibiotic prophylaxis prior and after certain dental and nondental medical procedures. Talk to your doctor to find out whether you are at increased risk for this condition.
In addition:
• Take an antibiotic just before and after any procedure that may put you at risk
• Tell your dentist and other health professionals about your heart condition
• Maintain good oral hygiene:
o Brush your teeth twice daily
o Floss daily
o Visit your dentist for a cleaning at least every six months
• See your dentist if dentures cause discomfort
• Seek medical care immediately for symptoms of an infection