Background Objective of this study to discover the relationship between secondary atrial septal defect (ASD) and pulmonary arterial pressure (PAP) in children less than 5 years old.

Methods Patients whose ages were less than 5 years old were admitted and underwent percutaneous occlusion of ASD with occluder in general anaesthesia with ketamine in General Hospital of Shenyang Military Command from April, 2000 to January, 2011. The patients were divided into different groups according to size of the ASD and PAH.

Results 189 patients were concluded, male was 77 cases (40.7 per cent), female was 112 (59.3 per cent), ratio was 1:1.5, mean ages were 4.1 ± 0.9 years old (range from 2 to 5 years), mean weights were 17.2 ± 3.6 kilograms (range from 10.0 to 30.0 kg), mean highs were 104.9 ± 9.2 cm (range from 77 to 135 cm), mean body surface areas (BSA) were 0.71 ± 0.10 m² (range from 0.46 to 1.02 m²), mean sizes of ASD were 12.6 ± 4.8 mm (range from 5 to 29 mm), mean sizes of ASD modified by BSA were 18.0 ± 7.0 mm/ m² (range from 5.3 to 38.9 mm/ m²). Mean systolic PAPs were 41.1 ± 8.9 mmHg (range from 15 to 67 mmHg), mean diastolic PAPs were 16.8 ± 6.5 mmHg (range from 3 to 45 mmHg), mean PAPs were 24.9 ± 6.7 mmHg (range from 12 to 48 mmHg). 159 patients (89.4%) had pulmonary arterial hypertension measured by right heart catheterization (RHC), but no patient had PAH by echocardiography. PAPs had no difference in different size ASDs (p >0.05).

Conclusions There was no relationship between the sizes of ASD and PAP in children less than 5 years old. PAH maybe been not caused by shunts through ASD.