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

OBJECTIVE: To establish an animal model of congenital heart defect with decreased pulmonary blood flow for better understanding the pathophysiology of pulmonary vascular development and related regulatory mechanisms of congenital heart defect with decreased pulmonary blood flow. METHOD: One to two months old pigs were randomly divided into three groups: control group (group C, n = 6) with right chest small incisions induced transient pulmonary blood reduction; light-moderate stenosis groups (group T(1), n = 7): artificial atrial septum defect (ASD) plus controlled pulmonary artery banding to generate a systolic pressure gradient of 20 - 30 mm Hg (1 mm Hg = 0.133 kPa); severe stenosis groups (group T(2), n = 7): similar surgical procedures as group T(1), and controlled pulmonary artery banding to generate a systolic pressure gradient ≥ 30 - 50 mm Hg. 64-slice computed tomography scanning was performed at one month post operation. Arterial blood gas analysis, hemoglobin value, pulmonary vessel, ASD and banding ring diameters and trans-pulmonary artery banding pressure (Trans-PABP) were determined at two months post operation. RESULTS: One pig died due to tracheal intubation accident in the C group, one pig died due to bowel obstruction in the T(1) group and two pigs died due to acute right heart failure and chronic heart failure respectively in T(2) group. 64-slice CT angiography results showed that aortic diameter of T(1) group was significantly lower than that of C group and banding diameter was significantly lower than aortic diameter in the T(1) and T(2) groups at one month post operation. Two months after operation, the size of ASD were (8.0 ± 0.5) mm and (8.9 ± 1.4) mm (P > 0.05) respectively in the T(1) and T(2) groups after operation. The Trans-PABP was significantly higher in the T(1) and T(2) groups than in C group (P < 0.01), and the Trans-PABP was significantly higher in the T(2) group than in T(1) group (P < 0.01). PaO2 and SaO2 in the T(1) and T(2) groups were significantly lower than those in C group. CONCLUSION: Artificial atrial septum defect combined pulmonary artery banding procedures could be successfully used to establish model of congenital heart defect with decreased pulmonary blood flow and this model could help to understand the pathophysiology and monitor therapy efficacy for patients with congenital heart defect with decreased pulmonary blood flow.

[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.