Sökning: "ductus venosus"
Visar resultat 1 - 5 av 6 avhandlingar innehållade orden ductus venosus.
1. Fetal Cardiac Function and Venous Circulation - Experiences with Velocity Vector Imaging
Sammanfattning : Placental dysfunction resulting in intrauterine growth restriction (IUGR) is a common complication of pregnany and severe IUGR, with ensuing fetal hypoxia is an important cause of perinatal mortality and morbidity. Doppler studies of fetal and maternal vessels are routinely used for fetal surveillance and alterations in fetal venous blood flow has been demonstrated as a late sign of fetal compromise. LÄS MER
2. Role of cerebral Blood Flow in Fetal Surveillance
Sammanfattning : ABSTRACT In high-risk pregnancies the chronic hypoxemic fetus redistributes its circulation to maintain the blood supply to the vital organs: brain, heart and adrenals. The aims of the studies included in this thesis were: 1) to establish reference curves for fetal cerebral venous blood velocity in normal pregnancies; 2) to determine in high-risk pregnancies the frequency of abnormal Doppler in the cerebral veins and uterine, umbilical and middle cerebral arteries and the umbilical vein and ductus venosus with correlation with adverse perinatal outcome; 3) to analyze the correlation between brain sparing and redistribution of circulation and placental vascular impedance; 4) to evaluate the correlation between brain sparing and fetal umbilical cord blood gases at birth. LÄS MER
3. Brain-sparing Circulation in Growth-restricted Human Fetuses
Sammanfattning : The aim of the studies was to explore fetal circulatory changes relative to development of brain-sparing flow (BSF) in growth-restricted fetuses exposed to acute hypoxic stress, as provoked by uterine contractions during an oxytocin challenge test (OCT).(1) In fetuses with a normal cerebral circulation during basal conditions, signs of an acute hyperperfusion in both the arterial and venous cerebral vascular systems were demonstrated in response to acute hypoxic stress; (2) Fetuses with an already established BSF showed no further ability of brain-sparing during acute hypoxic stress; (3) In venous cerebral vessels of fetuses with established BSF, the flow responses to hypoxic stress were equivocal, indicating different reactions in areas drained by different veins, or a deranged physiological vascular response; (4) Blood flow changes occurred synchronized in the middle and anterior cerebral arteries when fetuses with an intact cerebral circulation were exposed to hypoxic stress; (5) When fetuses with an established BSF showed no further changes in the middle cerebral artery, no changes were found in the anterior cerebral artery either. LÄS MER
4. Audio spectrum analysis of umbilical artery Doppler ultrasound signals
Sammanfattning : The aim of this thesis was to develop an objective method for evaluation of umbilical artery circulation based on auditory perception of the Doppler sound signals. Study I. The operator listened to synthetically produced sound signals from continuous flow. LÄS MER
5. Doppler Velocimetry in the Evaluation of Fetal Well-Being
Sammanfattning : Ultrasound Doppler velocimetry was used to predict fetal well-being. The uterine artery blood velocimetry seemed to be a good predictor of perinatal outcome in high-risk pregnancies and a complement to umbilical artery velocimetry. The fetal middle cerebral artery blood velocimetry might be an early sign of fetal hypoxia. LÄS MER
