title: Hypoplasia of the small pulmonary arteries in total anomalous pulmonary venous connection with obstructed pulmonary venous drainage.
abstract: OBJECTIVE
  Preoperative pulmonary venous obstruction has been reported to be a risk factor negatively impacting survival in total anomalous pulmonary venous connection. We examined lung tissue from total anomalous pulmonary venous connection patients with pulmonary venous obstruction and demonstrated hypoplasia of small pulmonary arteries to elucidate the mechanism underlying the poor outcome.
  
  
  METHODS
  Ten total anomalous pulmonary venous connection patients with preoperative pulmonary venous obstruction between the ages of 2 days and 10 months were studied. As histological parameters, we assessed the size of small pulmonary arteries in relation to the size of accompanying bronchioles to identify small pulmonary artery underdevelopment. Other parameters, such as the radial alveolar count, which reflects alveolar maturity, intimal lesions, lymphangiectasia, and the medial thickness of small pulmonary arteries and small pulmonary veins, were also examined. As a control group, we examined 24 autopsy cases with no congenital heart or pulmonary disease.
  
  
  RESULTS
  When the radius of the accompanying bronchiole was 100 microm, the radius of small pulmonary artery in the control group was found to enlarge for the first 2 months and then remain stable at approximately 80 microm from 2 to 10 months. In total anomalous pulmonary venous connection with preoperative pulmonary venous obstruction, the radius was significantly lower than in the control (47.0 +/- 21.8 microm versus 75.9 +/- 9.8 microm, P <.001), and the difference between dead and surviving patients was significant at P <.001 (33.0 +/- 14.6 microm versus 68.2 +/- 9.2 microm). Examination of the alveoli yielded an radial alveolar count of 4.6 +/- 1.5 in the control group and 4.4 +/- 0.8 in the total anomalous pulmonary venous connection patients, and the difference was not significant (P =.71).
  
  
  CONCLUSIONS
  The small pulmonary arteries of total anomalous pulmonary venous connection patients with preoperative pulmonary venous obstruction were underdeveloped compared with controls but their alveolae were not hypoplastic. These results suggested that the small pulmonary artery hypoplasia may be responsible for the poor outcome of these patients.
authors.affiliation: Department of Cardiothoracic Surgery, Graduate School of Medicine, University of Tokyo, Japan. maedak-tky@umin.ac.jp
authors.forename: Katsuhide
authors.initials: K
authors.lastname: Maeda
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yamaki
authors.forename: Michio
authors.initials: M
authors.lastname: Yokota
authors.forename: Arata
authors.initials: A
authors.lastname: Murakami
authors.forename: Shinichi
authors.initials: S
authors.lastname: Takamoto
mesh_terms: D000367:Age Factors; D001980:Bronchi / Q000002:abnormalities; D006801:Humans; D006976:Hypertension, Pulmonary / Q000151:congenital / Q000401:mortality; D007223:Infant; D007229:Infant Welfare; D007231:Infant, Newborn; D008200:Lymphangiectasis / Q000151:congenital / Q000401:mortality; D011651:Pulmonary Artery / Q000002:abnormalities*; D011667:Pulmonary Veins / Q000002:abnormalities*; D011668:Pulmonary Veno-Occlusive Disease / Q000151:congenital* / Q000401:mortality; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome; D017539:Tunica Intima / Q000002:abnormalities