Relationship between clinical pathophysiology and pulmonary pathology in patients with congenital heart defects and decreased pulmonary artery blood flow

OBJECTIVE: To investigate the relationship between pulmonary pathological features and clinical physiology of congenital heart defects (CHD) with decreased pulmonary artery blood flow. METHODS: Between July 2001 and May 2006, 18 patients with CHD with decreased pulmonary artery blood flow undergoing palliative or definitive repair and having lung biopsy intraoperatively were enrolled in this study. The patients' age was 0.4 - 8.0 years, and body weight was 6.0 - 20.0 kg. The method of semi-quantitative morphometric technique and an image analyzer were applied to measure the following indices of pulmonary microvessels: the percentage of media thickness (MT%), the percentage of media section area (MS%) and numbers of microvessels per square centimeter (VPSC). The diameters of left pulmonary artery (LPA) and right pulmonary artery (RPA) were measured with two-dimensional echocardiography. The percutaneous oxygen saturation (SpO(2)), hemoglobin concentration (HB) and hematocrit value (HCT) were examined and recorded preoperatively. RESULTS: There was a significant negative correlation between SpO(2) and HCT or Hb (R(2) = 0.4914, P = 0.001 and R(2) = 0.5505, P < 0.001), the variation trend of these three variables was linked. There was a negative correlation between SpO(2) and the body weight (R(2) = 0.2208, P = 0.049), which is in accordance with clinical features of aggravated process of cyanosis and hypoxia. The morphological observation of lung biopsy specimens indicated that most of peripheral pulmonary arteries were distended, irregular and their walls were uneven, and "lake" type of pulmonary AV malformations were observed. There was a positive correlation between VPSC and the body weight or BSA (R(2) = 0.5472, P < 0.001 and R(2) = 0.5233, P = 0.001). There was a significant correlation between VPSC and LPA or RPA (R(2) = 0.4312, P = 0.003 and R(2) = 0.2463, P = 0.036). It was shown that the diameter of central pulmonary arteries could be a reflection of peripheral pulmonary artery growth. The diameter of LPA also correlated with the diameter of RPA (R(2) = 0.286, P = 0.022). CONCLUSIONS: For patients with congenital heart defects with decreased pulmonary blood flow, the pulmonary pathological changes are the bases of their clinical physiologic features. It is suggested that they should be treated in their earlier stage of life.