OBJECTIVETo analyse the relationship between the quantitative structural study of lung and right ventricle outflow tract reconstruction in infants with tetralogy of Fallot.

METHODSLung biopsies were taken during the operations in 16 infants suffered from tetralogy of Fallot. Autopsy specimens were obtained from 5 infants died of non-cardiovascular diseases as normal control group. All patients underwent one staged repair. The techniques of right ventricular outflow tract reconstruction included pulmonary valve commissurotomy (n = 3), transanular pericardial patch (n = 4), and transannular homologous monocuspid valve patch (n = 8); homograft was used in one patient because of the abnormal coronary artery. The diameters of main pulmonary artery (MPA), left pulmonary artery (LPA), and right pulmonary artery (RPA) were measured during operation. The tissue was fixed with buffered formalin and routinely impregnated in wax. Sections were stained by hematoxylin-eosin, and Weigert's elastic stain counter-stained by van Gieoson's method. Seven parameters of the small pulmonary arteries were obtained, including percentage of media thickness (% MT), percentage of media section area (% MS), numbers of pulmonary small artery per square centimeter (APSC), mean alveolar number (MAN), mean linear intercept (MLI), proportion of parenchyma area in total area (% PPA), and alveolar/ small arterial ratio per unit area (AAR) by a computer-based image processor for quantitative analysis.

RESULTSIn the TOF group, % MT, % MS, and APSC significantly decreased, while MLI and AAR significantly increased (P < 0.05, compared with the control group). APSC decreased in turn after separately using three different techniques of right ventricular outflow tract reconstruction (i. e. pulmonary valve commissurotomy, transannular pericardium patch, and transannular homologous monocuspid valve patch), which was paralleled with the diameters of MPA, LPA, and RPA. RPA correlated with APSC (r = 0.754, P = 0.001).

CONCLUSIONSThe development of pulmonary small arteries and alveoli are directly affected by the diminished pulmonary flow in infants with tetralogy of Fallot. Right ventricle outflow tract reconstruction may be indicated according to the developmental degree of central pulmonary artery.