Andersons pediatric cardiology 1456

Background and Epidemiology ARF, a delayed autoimmune reaction to group A streptococcal infection, is now rarely seen in high-income countries, where RHD is predominantly reported in the aging population as a consequence of ARF several decades earlier, usually occurring during childhood.1 However, in the world's poorest populations, RHD remains a leading noncommunicable disease of the young.2 In 2010, an estimated 34.2 million people worldwide had RHD, resulting in 345,110 deaths and 10.1 million disability-adjusted life-years lost per annum.2 These Global Burden of Disease figures could be an underestimate due to limited global data, underdiagnosis, and scarce formal reporting systems.2,3 Regional heterogeneity exists regarding age of onset, mode of presentation, and specific valvar abnormality, which are influenced primarily by the socioeconomic and medical backgrounds of the populations involved.4,5 Global burden of disease is depicted in Fig 55.1.4 Children aged between 5 and 15 years are at greatest risk of a primary episode of ARF In endemic populations, the peak prevalence of RHD is between ages 25 and 45 years, reflecting the cumulative effect of recurrent episodes of ARF (Fig 55.2).6 FIG 55.1 Global prevalence of rheumatic heart disease from 1990 to 2013 FIG 55.2 Age and gender distribution of 3339 children and adults with rheumatic heart disease (RHD) in the international REMEDY registry of RHD Pathogenesis of Chronic Rheumatic Heart Disease The exact pathogenesis of ARF is incompletely understood RHD is thought to be the result of immune-mediated endothelial and connective tissue damage.7 Cardiac valves are especially prone to damage because of their thin structure, with a small core of connective tissue covered by two endothelial layers.7 The healing process of rheumatic valvulitis leads to varying degrees of neovascularization and fibrosis This process disturbs the delicate architecture of the valvar apparatus, leading to valvar regurgitation, stenosis, or both Clinical and echocardiographic regression and even resolution of mild to moderate disease is well documented.8–10 However, if the first episode of carditis results in more severe valvar dysfunction or if the valves are exposed to recurrent episodes of rheumatic fever, chronic deforming valvar damage and dysfunction develops.11 The pericardial effusion seen during the acute phase of rheumatic fever usually resolves with no long-term sequelae Myocardial impairment occurs only in the setting of severe valvar dysfunction, and recovery can be expected if timely surgical correction of the valvar dysfunction takes place.12–14 The hallmark of RHD is mitral valve (MV) disease: mitral regurgitation (MR), mixed MV disease, and/or pure mitral stenosis (MS) Although postmortem studies show universal MV involvement, echocardiographic studies reveal that isolated aortic valve (AV) disease occurs in approximately 2% to 8% of patients with RHD (Fig 55.3).15,16 In advanced disease, the tricuspid valve and, very rarely, the pulmonary valve may also be affected, but seldom if ever without MV involvement.17