New developments in the pulmonary circulation in children

This article reviews new advances in the diagnosis, treatment, and pathophysiology of pulmonary hypertension. In diagnosis, Doppler echocardiography has been refined and its accuracy increased, and magnetic resonance imaging is being developed as a new tool. Prostacyclin and calcium channel blockers remain mainstays of short-term therapy, and single-lung transplantation has become a new therapeutic option. Newer pharmacotherapeutics are largely directed at reversing acute vasoconstriction and include approaches related to ATP and endothelial-derived relaxing factor. In pathophysiology, recent studies have shown the role of elastase in mediating the initiation and progression of pulmonary hypertension, the regulation of gene expression of collagen, elastin, endothelin, and growth factors including transforming growth factor-B and insulinlike growth factor-I, and mechanisms of signal transduction of smooth muscle cell proliferation. The migratory smooth muscle cell phenotype has been studied in terms of altered expression of endothelial and smooth muscle extracellular matrix components, including hyaluronan and fibronectin, respectively.