[Image and hemodynamical features of pulmonary artery branches in COPD with pulmonary artery hypertension]

To investigate the imaging and hemodynamical features of pulmonary artery branches in chronic obstructive pulmonary disease (COPD) with pulmonary artery hypertension (PAH).

CT pulmonary angiography (CTPA) with ECG-gating was performed in 13 patients with clinical diagnosed COPD and 25 normal subjects. The thin-slice multiple plane reconstruction in systole and diastole phase was conducted, which in turn was used to generate the InSpace reconstructed images with reference frame of the main pulmonary artery and the first two grades branches, the contour of the branches was depicted. On the base of coordinates, the GAMBIT was used to generate nodes and furthermore meshes, then the software Fluent was used for numerical calculation and flow simulation. The velocity and pressure changes in the main pulmonary artery and the first two grades branches during different periods of cardiac cycle were observed in both groups.

CTPA showed that the diameter of the main pulmonary before bifurcate and proximal of the first two branches was larger in systole period than that in diastole period. The diameter of the second segmental artery of right upper lobe was larger during diastole period. The length of the main pulmonary and the first two branches showed no significant difference in both diastole and systole periods. There was no significant difference in length of pulmonary arteries between COPD and normal groups. The main pulmonary to distal right pulmonary artery appeared larger in diastole period. Compared with normal, in COPD group several arteries increased in diameter including proximal and distal of the proximal right pulmonary artery and the proximal right pulmonary artery during systole and diastole periods. In systole period only the diameter of the main pulmonary before bifurcate got larger and the back basic segmental artery of both lower lobe show smaller than normal. The flow condition analysis in COPD and normal groups suggested higher pressure in pulmonary arteries during systole period than that in diastole period, both groups showed high pressure area below the branching point. In COPD patients the right lower lobe artery endured the most significant pressure fall during the two periods and high pressure distributed larger area than normal. Flow velocity in main branch was faster than lower grade branches and that in systole period was faster than that in diastole period. The trend of diffusion of high pressure area was more prominent in diastole period than normal and the influence more prominent.

The distal part of right pulmonary artery to lower lobe artery may be affected earlier when the pulmonary pressure increased. It is feasible to study the changes of flow condition in pulmonary artery branches though the combination of CTPA image and relevant software.