RT Book, Section A1 Rubin, Lewis J. A2 Fuster, Valentin A2 Harrington, Robert A. A2 Narula, Jagat A2 Eapen, Zubin J. SR Print(0) ID 1161717252 T1 PULMONARY HYPERTENSION T2 Hurst's The Heart, 14e YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9780071843249 LK accessmedicine.mhmedical.com/content.aspx?aid=1161717252 RD 2024/03/29 AB Pulmonary hypertension (PH) is a hemodynamic abnormality common to a variety of conditions and characterized by increased right ventricular (RV) afterload and work. The clinical manifestations, natural history, and reversibility of PH depend heavily on the nature of the pulmonary vascular lesions and the etiology and severity of the hemodynamic disorder, although individual variability exists. For example, subacute or chronic hypoxia predominantly causes increased muscularization of the small muscular pulmonary arteries and arterioles with the intima relatively intact. Relief of the hypoxia improves or occasionally reverses the process with little or no pathologic residue.1,2 In contrast, the lesions of systemic sclerosis (scleroderma), mostly confined to the intima of the small pulmonary arteries and arterioles, are usually progressive and irreversible. Unlike these two examples, which spare the pulmonary capillary bed, the pulmonary capillaries are the primary site of involvement in pulmonary capillary hemangiomatosis.3