Endocarditis pathophysiology
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Endocarditis Microchapters |
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Diagnosis |
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2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease |
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Endocarditis pathophysiology On the Web |
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Risk calculators and risk factors for Endocarditis pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The turbulent blood flow around the heart valves is a risk factor for the development of endocarditis. The valves may be damaged congenitally, from surgery, by auto-immune mechanisms, or simply as a consequence of old age. The damaged endothelium of these areas becomes a site for attachment of infectious agents in infectious endocarditis. Dental procedures, colorectal cancer, urinary tract infections and intravenous drug use are the most common routes of introducing the infectious agent into the bloodstream. The three most common pathogens are strepotococcus viridans, staphylococcus and enterococcus. In non-bacterial thrombotic endocarditis (NBTE), the damaged part of a heart valve becomes covered with a blood clot which organizes.
Pathophysiology
Pathogenesis
Infective Endocarditis
The pathogenesis of infective endocarditis includes:[1][2]
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Nonbacterial thrombotic endocarditis
Nonbacterial thrombotic endocarditis (NBTE), also called marantic endocarditis is most commonly found on previously undamaged valves.[2] As opposed to infective endocarditis, the vegetations in NBTE are small, sterile, and tend to aggregate along the edges of the valve or the cusps.[2] Also unlike infective endocarditis, NBTE does not cause an inflammation response from the body.[2] NBTE usually occurs due to hypercoaguable states such as systemic bacterial infection or pregnancy.[2] NBTE may also occur in patients with cancer, particularly mucinous adenocarcinoma.[2] Libman-Sacks endocarditis is another form of sterile endocarditis; this form occurs more often in patients with lupus erythematosus and is thought to be due to the deposition of immune complexes. Libman-Sacks endocarditis involves small vegetations, while infective endocarditis is composed of large vegetations.[2] These immune complexes precipitate an inflammatory reaction, which helps to differentiate it from NBTE.[2] Also unlike NBTE, Libman-Sacks endocarditis does not seem to have a preferred location of deposition and may form on the undersurfaces of the valves or even on the endocardium.[2]
Associated Conditions
Gross Pathology
Microscopic Pathology
Causes of Bacteremia
Dental Procedures
The bacteremia is often caused by dental procedures, such as a cleaning or extraction of a tooth. It is important that a dentist or a dental hygienist therefore be told of any heart problems before beginning the procedure. Prophylactic antibiotics are administered to patients with certain heart conditions as a precaution.
Entrance of Bacteria Into the Bloodstream
Another cause of infective endocarditis is a scenario in which an excess number of bacteria enter the bloodstream. Colorectal cancer, serious urinary tract infections, and IV drug use can all introduce large numbers of such bacteria. When a large burden of bacteria are introduced, a normal heart valve may be infected. A more virulent organism (such as Staphylococcus aureus, but see below for others) is often responsible for infecting a normal valve.
Intravenous Drug Use
Infections of the tricuspid valve and less frequently the pulmonic valve tend to occur in intravenous drug users given the high pathogen burden from their introduction in the vein. The diseased valve is most commonly affected when there is a pre-existing disease. In rheumatic heart disease this is the aortic valve and the mitral valves, on the left side of the heart.
Pathology
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Heart; Breast intraductal papilloma metastasis. Thrombotic Nonbacterial Endocarditis (Infected): Gross mitral valve natural color vegetations well illustrated these were secondarily infected with staphylococcus case of 8 year survival breast intraductal papillary adenocarcinoma with extensive metastases. Aortic valve also involved -
Thrombotic Nonbacterial Endocarditis Infected: Micro low mag H&E fibrin vegetation with masses of staphylococci and inflammatory cells in valve secondarily infected case 8 year survival breast papillary intraductal adenocarcinoma with extensive metastases gross is aortic valve lesions.
