Fetal Aortic Isthmus and Descending Aorta
(2023) p.213-242- Abstract
Doppler evaluation of the aortic isthmus, located between the left subclavian artery and the ductus arteriosus, can provide important information on fetal hemodynamic adaptation/deterioration related to intrauterine hypoxia. The aortic isthmus acts as a shunt deviating part of the blood flow from ductus arteriosus to the cranial circulation to maintain a normal oxygen delivery to the fetal brain. The aortic isthmus Doppler waveforms can be recorded in a sagittal plane or in a cross-sectional plane (at the level of three vessel view) of fetal thorax with similar results. Various semiquantitative indices have been proposed to describe the velocity waveform of aortic isthmus, e.g., isthmus flow index (IFI) based on the analysis of time... (More)
Doppler evaluation of the aortic isthmus, located between the left subclavian artery and the ductus arteriosus, can provide important information on fetal hemodynamic adaptation/deterioration related to intrauterine hypoxia. The aortic isthmus acts as a shunt deviating part of the blood flow from ductus arteriosus to the cranial circulation to maintain a normal oxygen delivery to the fetal brain. The aortic isthmus Doppler waveforms can be recorded in a sagittal plane or in a cross-sectional plane (at the level of three vessel view) of fetal thorax with similar results. Various semiquantitative indices have been proposed to describe the velocity waveform of aortic isthmus, e.g., isthmus flow index (IFI) based on the analysis of time velocity integrals of the systolic and diastolic components of the waveform, the aortic isthmus pulsatility index (PI), and the isthmic systolic index. In severely growth restricted fetuses, an abnormal aortic isthmus blood flow precedes changes in the ductus venosus Doppler waveform by 1 week. An abnormal aortic isthmus blood flow is associated with increased risk of adverse perinatal outcomes. Ultrasound imaging and Doppler evaluation of the aortic isthmus importantly contribute to the identification of fetuses with coarctation of the aorta. Early Doppler studies of the fetal descending aorta focused on quantitative estimation of volume blood flow from the time-averaged mean blood velocity signals and aortic diameter, and reference values were established. In normal pregnancies as gestation advances, the percentage of blood flow forwarded to fetal organs and limbs increases and the percentage of blood flow forwarded to the placenta decreases. The estimation of aortic blood flow was found to be open to methodological errors; therefore, for clinical purposes, the waveform of maximum blood velocities was analyzed and characterized by the PI. Normally, there are positive flow velocities throughout the cardiac cycle both in the thoracic and abdominal fetal descending aorta. It was recognized early that the absence or reversal of end-diastolic flow velocities (ARED-flow) was associated with adverse outcome of pregnancy. By combining the PI and information on presence/absence or reversal of the end-diastolic flow, the aortic waveforms were categorized into four semiquantitative blood flow classes (BFC) that proved to have great clinical potential for characterization of fetal condition. It was found that the waveform changes in the descending aorta parallel those in the umbilical artery and the BFC approach was applied for the evaluation of umbilical artery Doppler waveforms. Simultaneous recording of Doppler signals from the fetal abdominal aorta and from the inferior vena cava can facilitate the classification of fetal arrhythmias. Abnormal flow velocity patterns in the fetal aortic isthmus and descending aorta in high-risk pregnancies are associated with increased perinatal mortality and morbidity and with impaired postnatal neurocognitive development. Thus, Doppler examination of the two vessel areas, together with examination of other vessel beds, can be applied for a more detailed study of redistribution of flow in the presence of fetal hypoxia.
(Less)
- author
- Maršál, Karel LU and Hernandez-Andrade, Edgar
- organization
- publishing date
- 2023-01-01
- type
- Chapter in Book/Report/Conference proceeding
- publication status
- published
- subject
- keywords
- Aortic isthmus, Blood flow classes, Blood flow redistribution, Coarctation of the aorta, Descending aorta, Doppler velocimetry, Fetal arrhythmias, Fetal growth restriction, Fetal hypoxia, Fetus, Isthmus flow index, Placental insufficiency, Pulsatility index
- host publication
- Doppler Ultrasound in Obstetrics and Gynecology, Third Edition
- pages
- 30 pages
- publisher
- Springer International Publishing
- external identifiers
-
- scopus:85163560995
- ISBN
- 9783031061882
- 9783031061899
- DOI
- 10.1007/978-3-031-06189-9_15
- language
- English
- LU publication?
- yes
- id
- ab5329e3-600e-4d47-a76b-4de6e8991a71
- date added to LUP
- 2023-11-07 15:15:03
- date last changed
- 2024-04-19 07:09:46
@inbook{ab5329e3-600e-4d47-a76b-4de6e8991a71,
abstract = {{<p>Doppler evaluation of the aortic isthmus, located between the left subclavian artery and the ductus arteriosus, can provide important information on fetal hemodynamic adaptation/deterioration related to intrauterine hypoxia. The aortic isthmus acts as a shunt deviating part of the blood flow from ductus arteriosus to the cranial circulation to maintain a normal oxygen delivery to the fetal brain. The aortic isthmus Doppler waveforms can be recorded in a sagittal plane or in a cross-sectional plane (at the level of three vessel view) of fetal thorax with similar results. Various semiquantitative indices have been proposed to describe the velocity waveform of aortic isthmus, e.g., isthmus flow index (IFI) based on the analysis of time velocity integrals of the systolic and diastolic components of the waveform, the aortic isthmus pulsatility index (PI), and the isthmic systolic index. In severely growth restricted fetuses, an abnormal aortic isthmus blood flow precedes changes in the ductus venosus Doppler waveform by 1 week. An abnormal aortic isthmus blood flow is associated with increased risk of adverse perinatal outcomes. Ultrasound imaging and Doppler evaluation of the aortic isthmus importantly contribute to the identification of fetuses with coarctation of the aorta. Early Doppler studies of the fetal descending aorta focused on quantitative estimation of volume blood flow from the time-averaged mean blood velocity signals and aortic diameter, and reference values were established. In normal pregnancies as gestation advances, the percentage of blood flow forwarded to fetal organs and limbs increases and the percentage of blood flow forwarded to the placenta decreases. The estimation of aortic blood flow was found to be open to methodological errors; therefore, for clinical purposes, the waveform of maximum blood velocities was analyzed and characterized by the PI. Normally, there are positive flow velocities throughout the cardiac cycle both in the thoracic and abdominal fetal descending aorta. It was recognized early that the absence or reversal of end-diastolic flow velocities (ARED-flow) was associated with adverse outcome of pregnancy. By combining the PI and information on presence/absence or reversal of the end-diastolic flow, the aortic waveforms were categorized into four semiquantitative blood flow classes (BFC) that proved to have great clinical potential for characterization of fetal condition. It was found that the waveform changes in the descending aorta parallel those in the umbilical artery and the BFC approach was applied for the evaluation of umbilical artery Doppler waveforms. Simultaneous recording of Doppler signals from the fetal abdominal aorta and from the inferior vena cava can facilitate the classification of fetal arrhythmias. Abnormal flow velocity patterns in the fetal aortic isthmus and descending aorta in high-risk pregnancies are associated with increased perinatal mortality and morbidity and with impaired postnatal neurocognitive development. Thus, Doppler examination of the two vessel areas, together with examination of other vessel beds, can be applied for a more detailed study of redistribution of flow in the presence of fetal hypoxia.</p>}},
author = {{Maršál, Karel and Hernandez-Andrade, Edgar}},
booktitle = {{Doppler Ultrasound in Obstetrics and Gynecology, Third Edition}},
isbn = {{9783031061882}},
keywords = {{Aortic isthmus; Blood flow classes; Blood flow redistribution; Coarctation of the aorta; Descending aorta; Doppler velocimetry; Fetal arrhythmias; Fetal growth restriction; Fetal hypoxia; Fetus; Isthmus flow index; Placental insufficiency; Pulsatility index}},
language = {{eng}},
month = {{01}},
pages = {{213--242}},
publisher = {{Springer International Publishing}},
title = {{Fetal Aortic Isthmus and Descending Aorta}},
url = {{http://dx.doi.org/10.1007/978-3-031-06189-9_15}},
doi = {{10.1007/978-3-031-06189-9_15}},
year = {{2023}},
}