Background: To evaluate the development of small pulmonary arteries of infants with complex congenital heart defect (CHD) with diminished pulmonary blood flow but without aortopulmonary collateral arteries, we compared the imaging data including diameter of the central pulmonary artery, McGoon ratio and pulmonary artery index (PAI), which were obtained by echocardiography and cardioangiography before operation.

Methods: Biopsy specimens were obtained from 46 infants suffering from complex CHD with diminished pulmonary blood flow but without aortopulmonary collateral arteries from January 2002 to September 2004. The infants were at their age of 6-36 months. They had undergone echocardiography and cardioangiography examinations. Autopsy specimens were obtained from 5 infants, aged 4-18 months, who died of non-cardiovascular diseases and served as normal controls. The tissue was fixed with buffered formalin, and routinely prepared by impregnated in wax. Tissue sections were stained with hematoxylin-eosin, Weigert's elastic stain counter-stained with van Gieson. Three parameters including percentage of media thickness (MT%), percentage of media section area (MS%) and numbers of small arterial per square centimeter (APSC) were obtained by morphologic quantitative analysis using a computer image processor. The diameters of the left pulmonary artery (LPA) and the right pulmonary artery (RPA) were measured by echocardiography and cardioangiography. The McGoon ratio and PAI were calculated according to the results of cardioangiography.

Results: There was no significant difference in MT% and MS% between the normal control group and the experimental group. The mean value was 11.44% and 18.34% in the normal control group. The mean value of APSC was significantly different between the two groups (408.58/cm2 and 217.15/cm2 respectively). The diameters of the main pulmonary artery (MPA), LPA and RPA measured echocardiographically were not correlated with pathological data (P>0.05). The diameters of the LPA and MPA (r=0.61, P=0.01), of the RPA and MPA (r=0.48, P=0.01), and of the RPA and LPA (r=0.57, P=0.01) were positively correlated. But the diameters of the LPA, RPA and MPA were not correlated with pathological parameters. The diameters of the LPA and RPA were positively correlated (r=0.378, P=0.015) as shown by cardioangiography. The McGoon ratio and PAI calculated by cardioangiography were correlated with APSC (r=0.51, P=0.001 and r=0.448, P=0.004).

Conclusion: The developing extent of small pulmonary arteries is correlated with the central pulmonary artery of infants suffering from complex CHD with diminished pulmonary blood flow but without aortopulmonary collateral arteries.

Key words: congenital heart defect; pulmonary artery; oligemia; cardioangiography; infant

World J Pediatr 2007;3(2):140-145