Echo-Doppler ultrasonographic assessment of resistance and velocity of blood flow in the ductus venosus throughout gestation in fetal lambs

• Published in: Theriogenology Vol. 70; no. 4; pp. 648 - 654
• Main Authors: Panarace, M., Garnil, C., Cané, L., Rodríguez, E., Medina, M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2008; [Oxford]: Butterworth-Heinemann; [New York]: Elsevier Science
• Subjects: animal tissues; Animals; blood circulation; Blood Flow Velocity - veterinary; blood gases; Color and spectral Doppler sonography; Ductus Arteriosus - physiology; Ductus venosus; Female; Fetal Blood - physiology; Fetal circulation; fetal development; Fetal Heart - physiology; fetus; Fetus - blood supply; health status; hypoxia; Lamb; lambs; monitoring; oxygen; oxygen requirement; Pregnancy; Resistance and velocity indices; risk assessment; Sheep; ultrasonography; Ultrasonography, Doppler - veterinary; Ultrasonography, Prenatal - veterinary; umbilical veins; validity; velocity; Resistance and velocity indices; Color and spectral Doppler sonography; Lamb; Fetal circulation; Ductus venosus
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2008.04.027

It has been postulated that during fetal hypoxia, the blood flow shunted through the ductus venosus increases and may account for upto 70% of the total umbilical flow. The objectives of the present study were to use ultrasonography to determine the velocities and waveform indices of blood flow in the ductus venosus in the fetal lamb. The ductus venosus of 15 lamb fetuses was evaluated weekly from Days 45 to 143 of gestation (Day 0=day of AI). The Doppler indices measured were: S/D, the systole/diastole ratio; RI, the resistance index; and PI, the pulsatility index. The velocity waveforms studied were: SV, the peak velocity during ventricular systole; D, the peak velocity during ventricular diastole; aV, the lowest forward velocity during atrial contraction; and TAMV, the time-averaged maximum velocity. Doppler indices from Days 52 to 143 were highly correlated: S/D versus PI (r=0.96, P<0.0001), and versus RI (r=0.93, P<0.0001); and PI versus RI (r=0.97, P<0.0001). Velocity indices were also positively correlated: velocity SV versus D (r=0.87, P<0.0001), versus aV (r=0.79, P<0.05), and versus TAMV (r=0.98, P<0.0001); D versus aV (r=0.88, P<0.05), and versus TAMV (r=0.87, P<0.05); and aV versus TAMV (r=0.82, P<0.05). Doppler indices were negatively correlated with SV (r=−0.22, P<0.03); D (r=−0.37, P<0.0001); TAMV (r=−0.32, P<0.05) and with aV (r=−0.67, P<0.05). The mean value of each Doppler index decreased 40% from Days 52 to 73 (e.g., PI from 0.82±0.08 to 0.51±0.10; P<0.05), with no significant changes thereafter. Mean (±S.E.M.) values of velocity indices SV, D, aV, and TAMV rose twofold from Days 60 to 115 of gestation (e.g., SV from 54.4±8.8cm/s to 104.9±19.7 and aV from 24.8±6.9 to 54.9±5.9; P<0.05). In conclusion, Doppler ultrasonography facilitated assessment of the blood flow pattern in the ductus venosus in lamb fetuses between Days 52 and 143.