OBJECTIVEAs an important method of hemodynamic assessment in idiopathic pulmonary arterial hypertension (IPAH), cardiac catheterization combined with pulmonary vasoreactivity testing remains with limited experience in children, and the acute pulmonary vasodilator agents as well as response criteria for vasoreactivity testing remain controversial. The aim of this study was to investigate the clinical importance, agent selection, and responder definition of cardiac catheterization combined with pulmonary vasoreactivity testing in pediatric IPAH.

METHODThe patients admitted to Department of Pediatric Cardiology of Beijing Anzhen Hospital between April 2009 and September 2013 with suspected IPAH, under 18 years of age, with WHO functional class II or III, were enrolled. All the patients were arranged to receive left and right heart catheterization and pulmonary vasoreactivity testing with inhalation of pure oxygen and iloprost (PGI2) respectively. Hemodynamic changes were analyzed, and two criteria, the European Society of Cardiology recommendation criteria (Sitbon criteria) and traditional application criteria (Barst criteria), were used to evaluate the test results.

RESULTThirty-nine cases of children with suspected IPAH underwent cardiac catheterization. In 4 patients IPAH was excluded; 4 patients developed pulmonary hypertension crisis. The other 31 patients received standard cardiac catheterization and pulmonary vasoreactivity testing. Baseline mean pulmonary artery pressure (mPAP) was (66 ± 16) mmHg (1 mmHg = 0.133 kPa), and pulmonary vascular resistance index (PVRI) (17 ± 8) Wood U · m². After inhalation of pure oxygen, mPAP fell to (59 ± 16) mmHg, and PVRI to (14 ± 8) Wood U · m² (t = 4.88 and 4.56, both P < 0.001) . After inhalation of PGI2, mPAP fell to (49 ± 21) mmHg, and PVRI to (12 ± 9) Wood U · m² (t = 7.04 and 6.33, both P < 0.001). According to the Sitbon criteria, the proportion of pure oxygen responders was 6.5% (3/31) , while PGI2 responders was 35.5%, and the difference was significant (P = 0.004). According to the Barst criteria, the proportion of pure oxygen responders was 16.1% (5/31), while PGI2 responders was 51.6% (16/31), and the difference was significant (χ² = 0.09, P = 0.001).

CONCLUSIONFor children with IPAH, cardiac catheterization combined with pulmonary vasoreactivity testing has important value in differential diagnosis, severity estimation, and treatment (including the emergency treatment) choices. Pulmonary hypertension crisis is an important complication of cardiac catheterization in pediatric IPAH. Younger age, general anesthesia, crisis history, and poor heart function are important risk factors for pulmonary hypertension crisis. PGI2 is a relatively ideal agent for vasoreactivity testing in children with IPAH, which has more responders than traditionally used pure oxygen.

RESULTSof responders are not completely consistent using different criteria, and comprehensive evaluation should be done according to the goals of treatment in clinical practice.