Acute pulmonary hypertension in infants and children: cGMP-related drugs

Pharmacologic strategies to reduce pulmonary vascular tone and to treat pulmonary hypertension originally aimed to enrich vascular smooth muscle cyclic adenosine monophosphate levels. Alternatively, increasing cyclic guanosine monophosphate (cGMP) also reduces pulmonary vascular tone. Inhaled nitric oxide is extremely efficacious in increasing cGMP and selectively reducing mean pulmonary arterial pressure in pediatric cardiac patients. It is considered standard treatment in most centers. However, not all patients respond to inhaled nitric oxide and withdrawal is sometimes problematic. This has prompted investigation of alternative methods to increase intracellular vascular smooth muscle cGMP. Phosphodiesterase type 5 is particularly abundant in the lung vasculature of patients with severe pulmonary hypertension. Its inhibition with the sildenafil class of drugs is now commonplace. Drugs that affect cGMP metabolism in children with acute pulmonary hypertension are the subject of this review and consensus statement. Oral sildenafil is recommended in postoperative pulmonary hypertension after failed withdrawal of inhaled NO (class I, level of evidence B). The effectiveness of prolonged treatment with sildenafil in documented postoperative pulmonary hypertension is not well established (class IIb, level of evidence C). Sildenafil is indicated in idiopathic pulmonary hypertension, although data have been extrapolated mainly from adult trial (class I, level of evidence A, extrapolated). Recently, completed pediatric trials have seemed to support this recommendation. Longer-acting and intravenous forms of phosphodiesterase type 5 inhibitors, brain natriuretic peptides, and direct soluble guanylate cyclise activators all have appeal, but there is insufficient experience in children with acute pulmonary hypertensive disorders for recommendations on treatment.