Endocarditis can be classified as either infective or non-infective, depending on whether a foreign organism is causing the problem.
Infective Endocarditis As the valves of the heart do not actually receive any blood supply of their own, which may be surprising given their location, defense mechanisms (such as white blood cells) cannot enter. So if an organism (such as bacteria) establish hold on the valves, the body cannot get rid of them.
Normally, blood flows pretty smoothly through these valves. If they have been damaged (for instance in rheumatic fever[?]) bacteria have a chance to take hold.
Nowadays, the terms short incubation (meaning about less than six weeks), and long incubation (greater than six weeks), are preferred.
surgery, by auto-immune[?] mechanisms, or simply as a consequence of old age.
In a healthy individual, a bacteraemia[?], (where bacteria get into the blood stream through a minor cut or wound,) would normally be cleared quickly with no adverse consequences. If a heart valve is damaged, this provides a place for the bacteria to multiply, and an infection is established.
Another group of causes result from a high number of bacteria getting into the bloodstream. Bowel cancer[?], bad urinary tract infections and IV drug[?] use, can all introduce large numbers of bacteria. With a large number of bacteria, even a normal heart valve may be infected. A more virulent organism (such as Staphylococcus aureus) is usually responsible for infecting a normal valve.
Intravenous drug users tend to get their right heart valves infected, the veins enter into the right side of the heart. The injured valve is most commonly affected when there is a pre-existing disease. (In rheumatic heart disease this is the aortic and the mitral valves, on the left side of the heart.)
blood culture[?], where the patient's blood is removed, and any growth is noted and identified.
Alpha-haemolytic streptococci, that are present in the mouth will often be the organism isolated if a dental procedure caused the bacteraemia.
If the bacteraemia was introduced through the skin, such as contamination in surgery, an catheterisation, or in an IV drug user, Staphylococcus epidermidis and S. aureus are common.
Some organism when isolated give valuable clues to the cause, as they tend to be specific.
antibiotics need to be used. This is also because of the limited blood supply to the valves.
This is continued for a long time. If not effective, surgical removal of the valve is possible.