Endocarditis, also called infectious endocarditis is an infection and inflammation of the membrane and valves inside the heart chambers, called the endocardium. Endocarditis occurs when infectious organisms such as bacteria or fungi, enter the bloodstream and lodge in the heart.
In most cases, these organisms are streptococci, staphylococci or species of bacteria that normally live in the surface regions of the body. Infectious organisms enter the bloodstream through a break in the skin caused by a problem or injury to the skin, dental or medical intervention, or a cut in the skin, especially among people who use drugs into the veins.
Depending on the aggressiveness (virulence) of the infectious agent, the heart damage caused by endocarditis can be rapid and severe (acute endocarditis) or slower and less dramatic (subacute endocarditis).
Endocarditis Acute: occurs when an aggressive species of skin bacteria, especially staphylococcus, enters the bloodstream and attack a normal heart valve is not damaged. Once bacteria multiply within the heart, leaving small groups of bacteria called septic emboli into the bloodstream to spread the infection to other organs, especially kidneys, lungs and brain. People who use intravenous drugs (within the veins) are at high risk for acute endocarditis because many needle pricks staphylococci give many opportunities to enter the bloodstream through the skin lesions. The elements that are used in conjunction with drugs increase risk. If untreated, this form of endocarditis can be fatal in less than six weeks.
Subacute endocarditis: this form of endocarditis is caused by one of the viridans group streptococci (Streptococcus sanguis, mutans, mitis or milleri) that normally live in the mouth and throat. The streptococcus bovis or Streptococcus equinus may also cause subacute endocarditis, usually in patients who have some form of gastrointestinal cancer, colon cancer usually. Subacute endocarditis tends to affect the heart valves are already damaged in some way, usually, unlike acute endocarditis are less likely to cause septic emboli. If untreated, subacute bacterial endocarditis can worsen over a year until it becomes a deadly disease.
Endocarditis strikes approximately 19,000 people each year in the United States and causes over 2,000 deaths. Men develop endocarditis more than women and the disease is most common among people who have one or more of the following risk factors:
- a congenital (at birth) heart or heart valve, or mitral valve prolapse with valve regurgitation.
- a heart valve damaged by rheumatoid fever or valve thickening with calcium deposits, related to the age of the person.
- a device implanted in the heart (pacemaker wire, an artificial heart valve)
history of intravenous drug use
- a chronic medical condition that weakens the immune system (alcoholism, diabetes, cancer chemotherapy)
In about 20 percent of patients who have artificial heart valves and not intravenous drug users, may not identify a heart problem that could increase the risk for endocarditis. In 10 to 20 percent of patients with endocarditis who have artificial heart valves, infections that occur within 60 days after valve surgery are often caused by staph, while endocarditis that appears later is often caused by a streptococcus.
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