[Dopplersonography of the ductus venosus: assessment, evaluation and actual clinical importance]

Abstract

The ductus venosus (DV) connects the intra-abdominal umbilical vein with the infundibulum of the IVC and develops during pregnancy to a trumpet-shaped structure with a narrow isthmus that accelerates the blood jet crossing the IVC directly to the left atrium via the foramen ovale avoiding mixing with deoxygenated blood from the right chamber. In animal studies, blood flow and doppler sonographically analyzed blood flow velocity waveforms mainly is controlled by heart rate and central venous pressure. The velocity waveform of the DV contains two peak components: the first indicates systolic velocity of the ventricle, the second peak diastolic velocity. A nadir is seen during atrial contraction. In animal studies, DV blood velocity in hypoxemia is influenced by central venous pressure and heart rate. The determination of the DV/UV ratio reflects the redistribution of blood flow, increases in hypoxemia and is therefore more reliable than blood velocity measurement for the detection and evaluation of fetal distress. In cases with severely growth-restricted fetuses, recipient twin in TTTS (twin-to-twin transfusion syndrome), tachyarrhythmia-induced cardiomyopathia and congenital heart disease, the measurement and interpretation of DV Doppler waveform pulsatility seems to be a useful tool that provides important information on the fetal condition and outcome. In cases of zero or reverse flow during atrial contraction in most cases the delivery of the fetus is indicated. An improvement of morbidity and mortality using Doppler sonography of the DV has not yet been proven. In cases of fetuses with or without chromosomal aberrations with major defects of the heart it can be used in addition to the standard screening methods of the first trimester of pregnancy for detection of heart failure.