Biomechanical and Molecular Aspects of Pulmonary Vascular Disease in Children with Congenital Heart Disease

Abstract

Pulmonary hypertension and increased pulmonary blood flow both lead to functional and structural changes in the pulmonary vasculature. Pulnlollary vascular disease constitutes an ongoing threat to children with congenital heart disease. Without .early surgical repair, an estimated 30% of patients with congenital heart disease will develop signitlcant pulmonary vascular disease. Pulmonary hypertension and pulmonary vascular disease arc important causes of morbidity and mortality in patients with congenital heart disease. Pulmonary plexogenic arteriopathy is a eharactetistic form of pulmonary vascular disease and is most frequently associated with congenital heart defects. The combination of increased pulmoluu')' blood t10w with elevated pulmonary artery pressure, causes a rapid progression of the pulmonary vascular remodeling process that may progress to irreversibility and, then, precludes curative therapy or both the heart- and the vascular disease. Although the time course in which pulmonary arteriopathy progresses towards this stage is highly variable in different patients and different heart defects, our current knowledge, mainly based on empiricism, has lead to management strategies in pediatric cardiology Owt aims at surgical interventions early in life. On the other hand, at present, surgical corrections of complex congenital heart diseases may be delayed because of a staged approach. In addition, earlier and potentially reversible stages of plexogenic arteriopathy can jeopardize the outcome of surgical procedures because of acute pulmonary hypertensive crises perioperativcly. This aspect is of special importance in dIe management of patients with a univentricular heart, who will undergo Norwood- or Fontan procedures. These procedures are being performed in a rapidly increasing frequency in the current era and create a circulation, in which no ventricular force faces the pulmonary vasculaturc. In such a condition, already early stages of pulmonary vascular disease may be detrimental to surgical outcome and prognosis