Infective endocarditis is an infection of the lining of the heart (endocardium) and often involves the valves of the heart as well as any areas with abnormal connections between the chambers of the heart or its blood vessels.  It occurs when bacteria in the bloodstream clump on previously injured heart valves. Risk factors for endocarditis include injection drug use; compromised immune system; congenital heart defects; having a prosthetic (artificial) heart valve, pacemaker, or defibrillator; and deteriorated heart valves due to the aging process.   Acute bacterial endocarditis usually begins suddenly with a high fever, tachycardia, and fatigue.  Rapid and extensive heart valve damage occurs as a result.

Subacute bacterial endocarditis occurs gradually, causing symptoms like fatigue, low-grade fever, tachycardia, weight loss, diaphoresis, and anemia. Diagnostic tests for endocarditis include an echocardiograph to detect the damaged heart valves, a complete blood count, and blood cultures to identify the bacteria causing the infection.  Treatments include high doses of antibiotics that are given intravenously, but sometimes surgery is needed to repair or replace damaged heart valves.  Infective endocarditis affects twice as many men as women in all age groups. More than 25% of all cases occur in individuals over 60 years old. 

Non-infective endocarditis occurs when blood clots that do not have bacterial contamination form on the heart valves and endocardium.  It can progress to infective endocarditis if bacteria enter the bloodstream and attaches to the clots.  In both infective and non-infective endocarditis blood clots can break free from the endocardium and heart valves, causing blockage of the arteries at major organs and stroke.  

Risk Factors

The highest risk of Infective Endocarditis is in people who 

Inject illicit drugs

Individuals  who inject illicit drugs are at high risk of endocarditis because they are likely to inject bacteria directly into their bloodstream through dirty needles, syringes, or drug solutions. 

Have a weakened immune system

A weakened immune system cannot effectively fight the bacteria, which will quickly overgrow the bloodstream.  

Have a prosthetic heart valve, pacemaker or defibrillator

People who have a replacement heart valve are also at high risk. For them, the risk of infective endocarditis is greatest during the first year after heart valve surgery. After the first year, the risk decreases but remains slightly higher than normal. For unknown reasons, the risk is always greater with a replacement aortic valve than with a replacement mitral valve and with a mechanical valve rather than with a valve made from an animal.

Other risk factors for infective endocarditis are congenital birth defects of the heart, valves, and major blood vessels; heart valve damage from rheumatic fever; deterioration of heart valves because of the aging process; and calcium deposits on the valves.   

CAUSES OF INFECTIVE ENDOCARDITIS?

While bacteria are not usually found in the blood, an injury to the skin, lining of the mouth, or gums can allow a small number of bacteria to enter the bloodstream. Infections like those of the skin, gums and other areas of the body can also introduce bacteria into the bloodstream, as can certain dental, medical and surgical procedures.  Individuals with normal heart valves typically are not affected by this small number of bacteria in their bloodstream, as the body’s immune system activates and quickly destroys the bacteria.  For those individuals with damaged heart valves, the bacteria may clump on the valves, lodge in the endocardium, and begin to multiply.  Sepsis can also introduce a large number of bacteria in the bloodstream, effectively overwhelming the immune system, from which endocarditis can develop even in individuals with normal heart valves.  If the cause of infective endocarditis is associated with the injection of drugs or prolonged use of intravenous lines, the tricuspid valve (which opens from the right atrium into the right ventricle) is most often infected. With most other causes of endocarditis, the mitral valve or the aortic valve is infected.

In our next post, we will discuss the symptoms and diagnosis of Infective Endocarditis. All posts are from The Correctional Nurse Educator class entitled Endocarditis for the Correctional Nurse.

Have you had a patient with endocarditis in your Correctional Nursing practice? Share your experiences in the comments section of this post.