The Aortic Isthmus: A Significant yet Underexplored Watershed of the Fetal Circulation

Tynan, Dominique; Alphonse, Jennifer; Henry, Amanda; Welsh, Alec

doi:10.1159/000446942

Cited by 22 publications

(25 citation statements)

References 64 publications

(160 reference statements)

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“…This may explain why, despite a very small DTAA diameter Z-score, the risk assessment does not achieve a 100% success rate. Further refinement of prenatal diagnosis may be achieved with complementary physiological methods [30][31][32][33][34][35][36] . The association of aortic-arch hypoplasia in utero and BAV merits further study.…”

Section: Future Directionmentioning

confidence: 99%

Impact of prospective measurement of outflow tracts in prediction of coarctation of the aorta

Vigneswaran

Zidere

Chivers

et al. 2020

Ultrasound in Obstet & Gyne

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Objectives Prenatal diagnosis of coarctation of the aorta (CoA) is associated with reduced mortality and morbidity, however, accurate prenatal prediction remains challenging. To date, studies have used retrospective measurements of the outflow tracts to evaluate their potential to predict CoA. Our primary objective was to evaluate prospectively acquired measurements of the outflow tracts in fetuses with prenatally suspected CoA. A secondary aim was to report the postnatal prevalence of bicuspid aortic valve in this cohort. Methods Pregnancies with suspicion of isolated CoA and with a minimum of 6 months' postnatal follow‐up available were identified from the cardiac database of a tertiary fetal cardiology center in the UK, between January 2002 and December 2017. Measurement of the aortic valve, pulmonary valve, distal transverse aortic arch (DTAA) and arterial duct (AD) diameters were undertaken routinely in fetuses with suspected CoA during the study period. Z‐scores were computed using published reference ranges based on > 7000 fetuses from our own unit. Results Of 149 pregnancies with prenatally suspected CoA included in the study, CoA was confirmed within 6 months after birth in 77/149 (51.7%) cases. DTAA diameter Z‐score and the Z‐score of second‐trimester DTAA/AD diameter ratio were smaller in fetuses with postnatally confirmed CoA than those in false‐positive cases (–2.8 vs –1.9; P = 0.039 and –3.13 vs –2.61; P = 0.005, respectively). Multiple regression analysis demonstrated that the Z‐scores of DTAA and AD diameters were the only significant predictors of postnatal CoA (P = 0.001). Bicuspid aortic valve was identified in 30% of the false‐positive cases. Conclusions Measurement of DTAA and AD diameter Z‐scores can be used to ascertain risk for postnatal CoA in a selected cohort. The high incidence of bicuspid aortic valve in false‐positive cases merits further study with respect to both etiology and longer‐term significance. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

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Section: Future Directionmentioning

confidence: 99%

Impact of prospective measurement of outflow tracts in prediction of coarctation of the aorta

Vigneswaran

Zidere

Chivers

et al. 2020

Ultrasound in Obstet & Gyne

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“…The AoI behaves like a vascular shunt located between the origin of the left subclavian artery and the connection site of the DA to the DAo, which links the two parallel brachiocephalic and the subdiaphragmatic circulations. Abnormal development of the heart or the peripheral vascular impedance will induce a redistribution of the CCO through the AoI 8,47 . The DV connects the terminal end of the UV via the PS and approximately 20% to 30% of the UV blood flow is shunted by the DV to feed the inferior vena cava (IVC) directly 42,48 .…”

Section: Discussionmentioning

confidence: 99%

Impact of ductus arteriosus constriction and restrictive foramen ovale on global hemodynamics for term fetuses with d‐TGA

Zhang

Haneishi

2019

Numer Methods Biomed Eng

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The ductus arteriosus (DA) constriction and restrictive foramen ovale (FO) are known as the leading cause of compromise and death of fetuses with dextro‐transposition of the great arteries (d‐TGA). Although the d‐TGA fetal hemodynamics is of great importance in making diagnosis and management of the congenital heart defect, it remains poorly understood, particularly in terms of abnormal DA and FO. In this study, we developed a closed‐loop 0‐1D multiscale model of the fetal cardiovascular system (CVS) specified for the d‐TGA circulation and conducted a systematic study of the impact of the DA constriction and restrictive FO on fetal hemodynamics. We found that the DA constriction led to a pronounced increase in the pulmonary artery pressure, pulmonary and mitral valve (PV and MV) regurgitation as well as left heart volume; the restrictive FO was responsible for reducing MV E/A ratio, ie, the ratio of peak early filling and late diastolic filling velocities, and PV peak systolic flow (PSV) but could increase both aortic valve (AV) PSV and aortic isthmus systolic index (ISI). Moreover, the amount of blood flowing through the DA was observed equivalent to that through the FO; the influence of DA constriction on the cerebral and placental perfusions are larger than that of the FO. Our results demonstrate that the proposed fetal cardiovascular model may be a useful tool for studying the underlying mechanisms associated with d‐TGA fetal circulation and providing insights into its complex physiology and pathology.

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“…The aortic isthmus has been defined as a fetal watershed between the origin of left subclavian artery from the aortic arch and aortic end of ductus arteriosus, with a waveform representing the complex hemodynamic physiology associated with it. The systolic fraction consists of left and right ventricular output, and the diastolic consists of near downstream vascular impedance between the brachiocephalic and sub diaphragmatic fetal flows [4] . ~ 6 ~ It's waveform changes slightly throughout gestation.…”

Section: Introductionmentioning

confidence: 99%

Determination of gestational age specific aortic isthmus indices for use as reference in third trimester doppler study

Sharma¹,

Tiwari²,

Ganeshan³

et al. 2020

Int. J. Radiol. Diagn. Imaging

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Background: Doppler study of umbilical artery, middle cerebral artery, uterine arteries and ductus venosus which is done routinely has its own limitations. The emergence of aortic isthmus index as an ideal parameter that provide an early detection of hemodynamic disturbance inside the fetus in the late pregnancy due to its position as a shunt between right and left ventricle, has inspired the study. Aims and Objectives: To determine the gestational age specific changes in fetal aortic isthmus flow indices in third trimester gestation and to compare the changes with varying time period of third trimester of gestation. Materials and Methods: A total of 124 normal pregnancies with gestational age of 27 to 40 weeks by LMP were included in the study. Study was done during July, 2018 to March, 2019 in BLK super speciality hospital, Pusa Road, New Delhi. Aortic isthmus doppler flow indices namely PSV, EDV, RI, PI, S/D, MD and TAMAX were automatically calculated in GE volusonE8 machine and GE P6 machine with 2-5 MHz sectoral array and compared by their LMP derived gestational ages. The correlations of doppler indices with gestational age was determined by linear regression equation. Results: It was observed that PSV and TAMAX increases with gestational age with correlation coefficient r=0.436 and 0.414 respectively and p value <.005. MD and ED also show a positive increasing trend with gestational age. Conclusions: This study provides normative values of PSV, EDV, PI and TAMAX with gestational age in third trimester of gestation. Studies are needed for prognostic value of these indices.

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The Aortic Isthmus: A Significant yet Underexplored Watershed of the Fetal Circulation

Cited by 22 publications

References 64 publications

Impact of prospective measurement of outflow tracts in prediction of coarctation of the aorta

Impact of prospective measurement of outflow tracts in prediction of coarctation of the aorta

Impact of ductus arteriosus constriction and restrictive foramen ovale on global hemodynamics for term fetuses with d‐TGA

Determination of gestational age specific aortic isthmus indices for use as reference in third trimester doppler study

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