Epidemiology of pediatric pulmonary hypertension

Pulmonary hypertension (PH) is a rare condition. Data on adult PH patients is abundant, but data on pediatric PH are scarce. Nevertheless, in the past decade, increasing data concerning pediatric PH are becoming available, enabling this review of the epidemiology, characterization, and outcome of pediatric pulmonary hypertension.PH is a condition that is associated with a variety of diseases. It is a rare condition in children with a complex and age-specific presentation. Transient forms of pulmonary arterial hypertension (PAH), i.e., potentially reversible PAH, specifically occur in children and form the largest group of pediatric PH. Advanced PAH in children is predominantly idiopathic or associated with congenital heart disease. Other forms of PAH seldom occur in children. WHO PH groups 2-5 are rare in childhood; however, they may be underreported.The clinical presentation of pediatric PH is relatively nonspecific as it is in adults, with dyspnea on exertion as the most common presenting symptom. However, the clinical presentation of pediatric PH includes symptoms specific for children such as syncope. Pediatric PH frequently co-occurs with genetic and syndromal abnormalities, including Down syndrome. Right heart failure is less common in children despite a severe hemodynamic profile.PAH is a detrimental disease with a poor prognosis. Outcome of pediatric PAH differs between patients with different types of congenital heart disease. In the last decades, new PAH-targeted therapies have been developed, which have improved outcome in pediatric pulmonary arterial hypertension. However, currently reported survival rates vary and critical appraisal of patient populations, survival data, and proposed treatment approaches is necessary.</p

Epidemiology of pediatric pulmonary hypertension

Pulmonary hypertension (PH) is a rare condition. Data on adult PH patients is abundant, but data on pediatric PH are scarce. Nevertheless, in the past decade, increasing data concerning pediatric PH are becoming available, enabling this review of the epidemiology, characterization, and outcome of pediatric pulmonary hypertension.PH is a condition that is associated with a variety of diseases. It is a rare condition in children with a complex and age-specific presentation. Transient forms of pulmonary arterial hypertension (PAH), i.e., potentially reversible PAH, specifically occur in children and form the largest group of pediatric PH. Advanced PAH in children is predominantly idiopathic or associated with congenital heart disease. Other forms of PAH seldom occur in children. WHO PH groups 2-5 are rare in childhood; however, they may be underreported.The clinical presentation of pediatric PH is relatively nonspecific as it is in adults, with dyspnea on exertion as the most common presenting symptom. However, the clinical presentation of pediatric PH includes symptoms specific for children such as syncope. Pediatric PH frequently co-occurs with genetic and syndromal abnormalities, including Down syndrome. Right heart failure is less common in children despite a severe hemodynamic profile.PAH is a detrimental disease with a poor prognosis. Outcome of pediatric PAH differs between patients with different types of congenital heart disease. In the last decades, new PAH-targeted therapies have been developed, which have improved outcome in pediatric pulmonary arterial hypertension. However, currently reported survival rates vary and critical appraisal of patient populations, survival data, and proposed treatment approaches is necessary.</p

Right ventricular adaptation in congenital heart diseases

In the last four decades, enormous progress has been made in the treatment of congenital heart diseases (CHD); most patients now survive into adulthood, albeit with residual lesions. As a consequence, the focus has shifted from initial treatment to long-term morbidity and mortality. An important predictor for long-term outcome is right ventricular (RV) dysfunction, but knowledge on the mechanisms of RV adaptation and dysfunction is still scarce. This review will summarize the main features of RV adaptation to CHD, focusing on recent knowledge obtained in experimental models of the most prevalent abnormal loading conditions, i.e., pressure load and volume load. Models of increased pressure load for the RV have shown a similar pattern of responses, i.e., increased contractility, RV dilatation and hypertrophy. Evidence is accumulating that RV failure in response to increased pressure load is marked by progressive diastolic dysfunction. The mechanisms of this progressive dysfunction are insufficiently known. The RV response to pressure load shares similarities with that of the LV, but also has specific features, e.g., capillary rarefaction, oxidative stress and inflammation. The contribution of these pathways to the development of failure needs further exploration. The RV adaptation to increased volume load is an understudied area, but becomes increasingly important in the growing groups of survivors of CHD, especially with tetralogy of Fallot. Recently developed animal models may add to the investigation of the mechanisms of RV adaptation and failure, leading to the development of new RV-specific therapies.</p