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Children and adults with pulmonary arterial hypertension (PAH) have similarities and differences in their background characteristics, hemodynamics, and clinical manifestations. Regarding genetic background, mutations in BMPR2-related pathways seem to be pivotal; however, it is likely that other modifier genes and bioactive mediators have roles in the various forms of PAH in children and adults. In pediatric PAH, there are no clear sex differences in incidence, age at onset, disease severity, or prognosis but, as compared with adults, syncope incidence, pulmonary vascular resistance, and mean pulmonary artery pressure are higher, and vasoreactivity to acute drug testing is more frequent, among children. Nevertheless, the pharmacokinetic effects of 3 major pulmonary vasodilators appear to be similar in children and adults with PAH. This review focuses on the specific pathophysiologic features of PAH in children.

Background: Myocarditis (MC) is an important cause of cardiac dysfunction in children. Fulminant MC is sometimes fatal, and sequelae may develop during follow-up. We conducted a nationwide survey to determine the clinico-epidemiological features of MC in Japanese children and adolescents., Methods and Results: Survey questionnaires were mailed to 627 hospitals, which were asked if they had treated MC patients aged between 1 month and 17 years during the period from January 1997 through December 2002. Responses were collected until December 2005, and data were collected and analyzed until January 2008. A total of 169 patients were reported: 64 fulminant cases, 89 acute cases, and 8 chronic cases. Incidence was 43.5 cases/year and 0.26 cases/100,000. Pathogens were identified in 37 patients; coxsackie virus accounted for 60%. Major cardiovascular manifestations at onset were congestive heart failure, refractory arrhythmia, and syncope in 70, 37, and 17 patients, respectively. Intravenous immunoglobulin was administered to 73 patients. Mechanical support seemed to be effective and life-saving. Among the 169 patients, 123 survived. Cardiovascular sequelae were reported in 49 patients., Conclusions: The survival rate for children with fulminant MC was disappointing. Overall, two-thirds of survivors had no sequelae. Mechanical support may reduce the mortality and the risk of clinical worsening.