Rheumatic heart disease.
Following the initial attack, ARF can be reactivated by subsequent exposure to GAS. The development of rheumatic heart disease (RHD) may occur over years or even decades, as recurrent inflammation of the endocardium, and especially the heart valves, leads to increased fibrosis and scarring. The valves of the heart become permanently thickened and retracted, and leaflets (flaps of the heart valves) may adhere to each other. This stenosis of the valves causes dysfunction, with regurgitation and reduced opening.
The mitral valve (between the left atrium and ventricle) is most commonly affected, although 25 percent of people with RHD have mitral and aortic valve involvement. Valves in the right side of the heart are only rarely involved.As the aortic valve become increasingly dysfunction (AF) develops, The combination of stagnation of flow and AF may generate thombosis, leading to strokes. It also causes increasing pressure in the pulmonary circulation and ventricular hypertrophy that eventually leads to heart failure.
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 valves function. Common causative organisms are streptococcus viridans and other bacteria that form part of the normal flora of the mouth. These may penetrate the bloodstrem during dental care, making prophylactic antibiotic therapy essential for people with RHD undergoing dental procedures.
Mortality rate for RHD in regions with no access to treatment can be as high as 20 per cent within six years of diagnosis, due to severe heart failure. Pregnancy is particularly associated, the aim is to reduce complication of RHD - treating heart failure and AF, and reducing the risks of thromboembolism and infective endocarditis. Once valve disease becomes symptomatic, valves need to be repaired or replaced. Treatment of RHD is costly and uses a lot of resources - prevention is evidently farmore cost-effective for both developed and developing nations.