[Establishment of a cyanotic congenital heart defect porcine model with decreased pulmonary blood flow].

Objective: To establish a porcine model of congenital heart disease with decreased pulmonary blood to explore the morphological changes of immature pulmonary vascular vessels.

Methods: Twenty piglets (one to two-month-old) were randomly divided into three groups: sham-operated group (group S, n = 6), small incisions on the right chest, produced a transient reduction in pulmonary blood; Operation group 1(group T(1), n = 7), small incisions on the right chest, producing artificial atrial defect with self-made dilator and simultaneous banding pulmonary artery to generate a systolic pressure gradient between 20 - 30 mm Hg (1 m Hg = 0.133 kPa); Operation group 2(group T(2), n = 7): operation procedure was similar as group T(1) with systolic pressure gradient between 30 - 50 mm Hg. Lung tissue from right middle lobe (1.0 cm×0.8 cm×0.8 cm) was taken immediately after thoracotomy, at the end of surgery and at 2 months after operation and stained by Weigert (elastic fiber) and van Gieson (collagen) methods to observe the morphological changes.

Results: Five animals survived in Group S, 6 animals survived in group T(1) and 5 animals survived in group T(2). The inside diameter of pulmonary arterioles after thoracotomy and at the end of surgery was similar among the three groups (P > 0.05). At 2 months after operation, the inside diameter of pulmonary artery was significantly higher in group T(1) and T(2) than in group S (all P < 0.05) while the number of pulmonary small artery per square centimeter (APSC) of group T(1) and T(2) was significantly lower than that of group S (all P < 0.05). Tunica media of pulmonary artery was thinner and vascular lumen was larger in group T(1) and T(2) compared to those of group S.

Conclusion: In this piglets model with reduced pulmonary blood, the pulmonary arterioles underwent dysplastic changes. Thus, pulmonary blood flow is an important determinant for the physiological development of pulmonary artery.