Classification of Pulmonary Hypertension As early as 1891, Ernst von Romberg had described changes in the pulmonary vasculature in an autopsied patient with pulmonary hypertension, which he called sclerosis of the pulmonary arteries.1 Subsequently, the term primary pulmonary hypertension was coined in 1951.2 The original classification of chronic cor pulmonale was established by the World Health Organization in 1973 and has been revised numerous times The most recent adult revision occurred in Nice, France, at the Fifth World Symposium on Pulmonary Arterial Hypertension with five groups (Table 75.1).3 Because the associated diseases differ between children and adults with pulmonary hypertension, a pediatricfocused classification has also been proposed that has more emphasis on developmental and fetal origins of pulmonary hypertension (Table 75.2).4 The clinically functional classification established by the New York Heart Association for cardiac disease (Table 75.3) is used in an adapted form to assess the clinical severity and progression of the pulmonary vascular disease.3 Table 75.1 Classification of Pulmonary Hypertensive Diseases as Made by the World Health Organization (Nice, 2013) 1.1 1.2 1.21 1.22 1.23 1.3 1.4 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5 1′ 1″ 2.1 2.2 Pulmonary arterial hypertension Idiopathic Heritable BMPR2 ALK-1, ENG, SMAD9, CAV1, KCNK3 Unknown Drug and toxin induced Associated with: Connective tissue disease HIV infection Portal hypertension Congenital heart diseases Schistosomiasis Pulmonary venoocclusive disease and/or pulmonary capillary hemangiomatosis Persistent pulmonary hypertension of the newborn Pulmonary hypertension with left heart disease Left ventricular systolic dysfunction Left ventricular diastolic dysfunction 2.3 2.4 3.1 3.2 3.3 3.4 3.5 3.6 3.7 5.1 5.2 5.3 5.4 Valvar disease Congenital/acquired left heart inflow/outflow tract obstruction and congenital cardiomyopathies Pulmonary hypertension associated with lung diseases and/or hypoxemia Chronic obstructive pulmonary disease Interstitial lung disease Other pulmonary disease with mixed restrictive and obstructive pattern Sleep-disordered breathing Alveolar hypoventilation disorders Chronic exposure to high altitude Developmental lung diseases Chronic thromboembolic pulmonary hypertension Pulmonary hypertension with unclear multifactorial mechanisms Hematologic disorders: chronic hemolytic anemia, myeloproliferative disorders, splenectomy Systemic disorders: sarcoidosis, pulmonary histiocytosis, lymphangioleiomyomatosis Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders Others: Tumoral BMPR2, Bone morphogenetic protein receptor 2 Modified from Simonneau G, Gatzoulis MA, Adatia I, et al Updated clinical classification of pulmonary hypertension J Am Coll Cardiol 2013;62(25 Suppl):D34–D41 https://doi.org/10.1016/j.jacc.2013.10.029 Table 75.2 Pediatric Classification of Pulmonary Hypertension 10 Prenatal or developmental pulmonary hypertensive vascular disease Perinatal pulmonary vascular maladaptation Pediatric cardiovascular disease Bronchopulmonary dysplasia Isolated pediatric pulmonary hypertensive vascular disease (isolated pediatric PAH) Multifactorial pulmonary hypertensive vascular disease in congenital malformation syndromes Pediatric lung disease Pediatric thromboembolic disease Pediatric hypobaric hypoxic exposure Pediatric pulmonary vascular disease associated with other system disorders PAH, Pulmonary arterial hypertension Modified from Cerro MJ, Abman S, Diaz G, et al A consensus approach to the classification of pediatric pulmonary hypertensive vascular disease: report from the PVRI Pediatric Taskforce, Panama 2011 Pulm Circ 2011;1(2):286–298 Table 75.3 Classification of the Clinical Functional State in Patients With Pulmonary Hypertension According to the World Health Organization/New York Heart Association Class Patients with pulmonary hypertension, but without resulting limitation of physical activity Ordinary I physical activity does not cause undue dyspnea or fatigue, chest pain, or near syncope Class Patients with pulmonary hypertension resulting in slight limitation of physical activity They are II comfortable at rest Ordinary physical activity causes undue dyspnea or fatigue, chest pain, or near syncope Class Patients with pulmonary hypertension resulting in marked limitation of physical activity They are III comfortable at rest Less than ordinary activity causes undue dyspnea or fatigue, chest pain, or near syncope Class Patients with pulmonary hypertension with inability to carry out any physical activity without symptoms IV These patients manifest signs of right heart failure Dyspnea and/or fatigue may even be present at rest Discomfort is increased by any physical activity Modified from Simonneau G, Gatzoulis MA, Adatia I, et al Updated clinical classification of pulmonary hypertension J Am Coll Cardiol 2013;62(25 Suppl):D34–D41 https://doi.org/10.1016/j.jacc.2013.10.029 ... Isolated pediatric pulmonary hypertensive vascular disease (isolated pediatric PAH) Multifactorial pulmonary hypertensive vascular disease in congenital malformation syndromes Pediatric lung disease Pediatric thromboembolic disease... https://doi.org/10.1016/j.jacc.2013.10.029 Table 75.2 Pediatric Classification of Pulmonary Hypertension 10 Prenatal or developmental pulmonary hypertensive vascular disease Perinatal pulmonary vascular maladaptation Pediatric cardiovascular disease... Multifactorial pulmonary hypertensive vascular disease in congenital malformation syndromes Pediatric lung disease Pediatric thromboembolic disease Pediatric hypobaric hypoxic exposure Pediatric pulmonary vascular disease associated with other system disorders PAH, Pulmonary arterial hypertension