Deformation of the valves increases a person's risk of developing infective endocarditis. Bacteria penetrating the blood stream can seed on the roughened surfaces of the valves. Here they may trigger acute, or, more frequently, chronic inflammation that leads to the development of friable vegetative growths on the valve flaps. These growths are composed of fibrin, inflammatory cells and bacteria, and can embolise or cause further deterioration in valve function. (16) Common causative organisms are streptococcus viridans and other bacteria that form part of the normal flora of the mouth. These may penetrate the bloodstream during dental care, making prophylactic antibiotic therapy essential for people with RHD undergoing dental procedures