Pathogenesis
As previously mentioned, altered blood flow around the valves contributes to 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 part of a heart valve leads to formation of a local blood clot, a condition known as non-bacterial thrombotic endocarditis (NBTE). Altered blood flow, and thus infective endocarditis, are more likely in high pressure areas. Consequently, ventricular septal defects create more susceptibility than atrial septal defects. Damaged vascular endothelium will also promote platelet and fibrin deposition, upon which bacteria can take hold. Valvular lesions are a major cause of such damage, as are jet lesions resulting from ventricular septal defects or patent ductus arteriosus.
Read more about this topic: Infective Endocarditis