Value of color Doppler ultrasound in the diagnosis and prognosis of outflow tract obstruction after liver transplantation in children / 中华器官移植杂志

ABSTRACT

Objective:To explore the diagnostic efficacy of ultrasonography and follow-up outcomes of hepatic venous outflow obstruction after liver transplantation(LT)in children.Methods:From July 2017 to January 2022, 32 children diagnosed with outflow tract obstruction post-LT are designated as HVOO group and examined by digital subtraction angiography(DSA).All of them underwent balloon dilation.Thirty cases with no vascular complications are selected as control group.Color Doppler blood flow parameters are recorded, including peak systolic velocity(PSV), peak diastolic velocity(PDV), PSV/PDV(S/D), resistive index(RI), portal vein velocity(PVV), hepatic vein velocity(HVV), hepatic vein waveform, anastomotic velocity and waveform.Intravascular pressure values of DSA within 48h are recorded.The correlations between color Doppler flow parameters and intravascular pressure values are examined before and after tube expansion.The differences of color Doppler flow parameters before tube expansion between HVOO and control groups are compared.And receiver operating characteristic(ROC)curves are plotted for obtaining ultrasonic parameters' cut-off value.Patients with excellent recovery are selected for comparing the difference of color Doppler blood flow parameters before and after tube expansion and detect the trend of hemodynamics.Results:There is a positive correlation between anastomotic velocity of hepatic vein and inferior vena cava and DSA before and after tube expansion in HVOO group(r=0.483, 0.414, all P<0.05); S/D, RI and anastomotic velocity are higher in HVOO group than those in control group( Z=-3.275, P=0.001; t=3.437, P=0.001; Z=-5.677, P<0.01); PV and HVV are lower in HVOO group than those in control group( Z=-2.719, P=0.007; Z=-6.762, P<0.01); The waveforms of hepatic vein and anastomosis in HVOO group are mostly single-phase waves, accounting for 81.25%(26/32)and 53.12%(17/32).Control group is mostly of dual-phase wave.According to ROC curve analysis, area under curve(AUC)of HVV diagnosing HVOO is 0.996 with a critical value of 21.65 cm/s; AUC of hepatic vein anastomosis velocity is 0.92 with a critical value 162 cm/s and AUC of RI 0.76 with a critical value of 0.73.PVV and HVV values after tube expansion are higher than before tube expansion( Z=-2.233, P=0.026; Z=-4.45, P<0.01); Anastomotic velocity after tube expansion is lower than that before tube expansion( t=8.584, P<0.01).The waveforms of hepatic vein and anastomosis are mostly of single-phase waves(76.92%, 61.54%)before tube expansion and dual-phase wave(88.46%, 96.15%)after tube expansion. Conclusions:Color Doppler ultrasound is a preferred imaging modality for diagnosing HVOO and conducting postoperative follow-ups in children after LT because of its non-invasiveness, real-time, simplicity and rapidness.Furthermore, the diagnostic efficiencies of hepatic vein and anastomotic velocity are relatively high.