RÉSUMÉ
Objective To explore the clinical diagnostic value of Doppler flow parameters of right pulmonary artery ( RPA) in the diagnosis of fetal ventricular outflow tract obstruction . Methods Thirty-two cases of fetuses with left ventricular outflow tract obstruction ( LVOTO ) and 35 cases with right ventricular outflow tract obstruction (RVOTO) were enrolled ,and 107 normal singleton fetuses served as control group . The definition of different segments of RPA was as following :the proximal RPA was defined as the first segment just distal to the originating from the main pulmonary artery ( PA 1) ;the mid RPA was the most distal aspect of the RPA in the extraparenchymal segment ,just before the artery entering the right lung parenchyma ( PA2) ; and the distal RPA was defined as the intraparenchymal segment at the first branching point within the right lung ( PA3) . All Doppler parameters were obtained from three RPA segments , and the maximum flow velocity ( Vmax) ,minimum flow velocity ( Vmin) and pulsation index ( PI) of each segment in each group as well as PA1 segment velocity time integral ( VTI-PA1) and PA1 segment flow from three groups were compared . Results The results of comparison of control group with LVOTO and RVOTO demonstrated that there were significant differences in VTI-PA1 ,Vmin and PI among three RPA segments ( P <0 .05) . There were significant differences in PA1 flow volume ( P <0 .05) in LVOTO group comparing with control group and RVOTO group . However , there was no statistics difference in flow volume between RVOTO and control group ( P > 0 .05) . Significant differences were found in Vmax of all three RPA segments between RVOTO group and control group ( P<0 .05) . There were significant differences in Vmin and PI of the PA2 and PA3 segments between LVOTO and RVOTO group ( P < 0 .05) . The PI in PA2 and PA3 segments in the RVOTO group were lower than those in LVOTO and control group ( P <0 .05) . Conclusions The differences of PI in PA2 and PA3 segments of RPA between fetuses with ventricular outflow tract obstruction and normal fetuses can provide a reference for the differential diagnosis of fetal ventricular outflow tract obstruction .