OBJECTIVEThe assessment of pulmonary vascular reactivity plays an important role in the management of idiopathic pulmonary arterial hypertension (IPAH). The aim of this study was to explore the indications and methodology of pulmonary vasodilator testing in children with IPAH.

METHODSFrom October 2009 to June 2011, a cohort of pediatric patients with IPAH in WHO functional classes II to III were enrolled in the study. Right heart catheterization was performed in all patients. After baseline hemodynamics were obtained, adenosine infusions were started at a dose of 50 µg/(kg·min), increased by 25 µg/(kg·min) at 2 min intervals to a maximum of 250 µg/(kg·min) or until a positive acute response.

RESULTSA total of 15 patients with IPAH were enrolled in the study. The mean age of the patients was 6.3 yrs. Mean pulmonary artery pressure (mPAP) was (67.1 ± 15.9) mm Hg. Pulmonary capillary wedge pressure (PCWP) was (9.7 ± 2.9) mm Hg. Pulmonary vascular resistance index (PVRI) was (17.9 ± 7.5) Wood U·m(2). Three patients were responders, defined as a fall in mPAP of at least 10 mm Hg to a pressure level of 40 mm Hg or lower. Twelve patients were nonresponders according to the same criteria. Five out of the 15 patients experienced adverse effects, including chest discomfort (n = 1), systemic hypotension (n = 3) and bradycardia (n = 1). All side effects abated within 30-60 s of the discontinuation of the adenosine infusion.

CONCLUSIONAdenosine is an effective vasodilator in children with IPAH and can be used for safe and rapid assessment of vasodilator reserve in these patients.