The use of high-resolution computed tomography in the evaluation of pulmonary hemodynamics in patients with congenital heart disease: in pulmonary vessels larger than 1 mm in diameter.

High-resolution computed tomography (HRCT) was carried out in 36 patients with congenital left-to-right shunt disease and 10 normal control subjects to assess the feasibility of CT in the evaluation of pulmonary hemodynamics. The patients had a left-to-right or a bidirectional shunt and the hemodynamic data obtained by cardiac catheterization in these patients were compared to the information obtained by CT imaging. The pulmonary/systemic blood flow (Q(p)/Q(s)) ratio and pulmonic/systemic resistance (R(p)/R(s)) ratio had a significant correlation with the pulmonary artery/bronchus (PA/Br) ratio (r = 0.54 and r = -0.37, respectively) and pulmonary vein/bronchus (PV/Br) ratio (r = 0.66 and r = -0.66, respectively), and the R(p)/R(s) and mean PA pressure also showed a significant correlation with the PA/PV ratio (r = 0.53 and r = -0.61, respectively) in the mid-lung field when accompanying bronchi were 4. 0-5.9 mm in diameter. There was no correlation between the hemodynamic data and the size of the central and hilar PA or with the rate of PA tapering. With HRCT, it is possible to evaluate pulmonary hemodynamics in patients with congenital heart disease with a left-to-right or bidirectional shunt, particularly R(p)/R(s) and mean PA pressure, which have been very difficult to obtain noninvasively. The small-sized pulmonary vessel/Br ratio or the small-sized PA/PV ratio could offer very useful information, but the dimension of the central PA provided the least useful information.