Fetal Venous Circulation

Kiserud, T.

doi:10.1017/s0965539503001037

Cited by 22 publications

(11 citation statements)

References 132 publications

(178 reference statements)

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“…Experimental studies in fetal sheep show that blood distribution to the liver and ductus venosus is particularly sensitive to changes in umbilical venous pressure, blood viscosity, and an active regulation of diameter of the entire ductus venosus, resulting in altered regional blood flow. 3 The mechanisms regulating ductus venosus diameter and blood flow through the fetal liver are incompletely understood, but may include shear stress and nitric oxide in addition to differences in catecholamine responses between the two pathways 6,7 ; further research is required to define these mechanisms.…”

Section: Resultsmentioning

confidence: 99%

“…Blood flow (Q) was calculated as Qϭh ⅐ (D/2) 2 ⅐ ⅐ TAMX, where Dϭvessel diameter (mean of 5 to 10 measurements) and hϭspatial blood velocity profile coefficient (umbilical veinϭ0.5; ductus venosusϭ0.7). 3 Intraclass correlation coefficients (random-effects regression) to assess intraobserver variation were 0.97 and 0.96 for the umbilical vein and ductus venosus diameter, respectively. We obtained complete data in 381 subjects (93%) and derived percent shunting from the ratio ductus venosus flow/umbilical vein flow; the correlation coefficient between ductus venosus cross-sectional area and shunting was 0.74 (PϽ0.001).…”

Section: Methodsmentioning

confidence: 98%

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Fetal Liver-Sparing Cardiovascular Adaptations Linked to Mother’s Slimness and Diet

Haugen

Hanson

Kiserud

et al. 2005

Circulation Research

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114

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Fetal adaptations to impaired maternoplacental nutrient supply include altered regional blood flow. Whether such responses operate within the normal range of maternal body composition or diet is unknown, but any change in fetal liver perfusion could alter hepatic development, with long-term consequences for the risk of cardiovascular and metabolic disease. In 381 low-risk pregnancies, we found that the fetuses of slimmer mothers with lower body fat stores and those eating an unbalanced diet had greater liver blood flow and shunted less blood away from the liver through the ductus venosus at 36 weeks gestation. Consequences of such "liver-sparing" may underlie the increased cardiovascular risk of people whose mothers were slimmer and had lower body fat stores in pregnancy.T he processes controlling the growth of individual fetal organs are incompletely understood, but during mammalian development, changes in blood flow to an organ affect its growth and can have major lifelong effects on organ function. The fetus uses changes in blood flow to defend itself against an insult such as reduced oxygen availability. By distributing blood pumped by the heart toward essential organs, eg, the brain ("brain-sparing"), at the expense of organs such as muscle, gut and liver, the fetus reduces nonessential growth and economizes on oxygen demand. It is not known whether similar adaptive mechanisms regulate blood flow and growth in relation to fetal nutrient supply within the normal range: if so, such mechanisms may be invoked by maternal factors such as body fat stores and diet, and might in part underlie the link between the intrauterine environment and health in adulthood. 1 Materials and MethodsTo examine the relation between maternal body fatness and diet and fetal hepatic blood flow at 36 weeks gestation, we approached a low-risk population of 410 healthy women with singleton pregnancies and no major fetal abnormality. A study of this size has 90% power to detect a correlation coefficient of 0.16 between maternal body fatness and fetal hepatic blood flow at the 5% level. The women's heights, weights, skinfold thicknesses, mid-upper arm circumferences, and diet had been measured by trained research nurses before pregnancy in the Southampton Women's Survey. 2 We used Doppler ultrasound (Acuson Sequoia) to measure blood flow in the umbilical vein and ductus venosus; the ductus venosus shunts a proportion of well-oxygenated placental blood past the fetal liver, toward the heart and head (Figure 1). We measured internal vessel diameter (late-diastole) and time-averaged maximum velocity (TAMX) (insonation angle Ͻ30°) in the intraabdominal umbilical vein (straight portion, before hepatic parenchymal branches) and at the ductus venosus inlet. Umbilical vein TAMX was obtained during a 3-to 5-second period or, if flow was pulsatile, as the mean during three heart cycles. Ductus venosus TAMX was calculated as the mean during three heart cycles. Blood flow (Q) was calculated as Qϭh ⅐ (D/2) 2 ⅐ ⅐ TAMX, where Dϭvessel diameter (mean of ...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 98%

Fetal Liver-Sparing Cardiovascular Adaptations Linked to Mother’s Slimness and Diet

Haugen

Hanson

Kiserud

et al. 2005

Circulation Research

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114

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“…These 'early' changes are followed by elevations in placental blood flow resistance and venous Doppler indices. Abnormal venous Doppler waveforms have been taken widely to indicate hemodynamic decompensation, reflecting increased pressure in the right atrium and/or dilatation of the DV (Kiserud, 2003). DV flow abnormalities are regarded as a 'late' marker reflecting acute myocardial myopathy and acidemia.…”

Section: Disease Progression: Sequential Arterial and Venous Doppler mentioning

confidence: 99%

Aortic isthmus Doppler velocimetry: role in assessment of preterm fetal growth restriction

et al. 2010

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Intrauterine fetal growth restriction (IUGR) is an important pregnancy complication associated with significant adverse clinical outcome, stillbirth, perinatal morbidity and cerebral palsy. To date, no uniformly accepted management protocol of Doppler surveillance that reduces mortality and cognitive morbidity has emerged. Aortic isthmus (AoI) evaluation has been proposed as a potential monitoring tool for IUGR fetuses. In this review, the current knowledge of the relationship between AoI Doppler velocimetry and preterm fetal growth restriction is reviewed. Relevant technical aspects and reproducibility data are reviewed as we discuss AoI Doppler and its place within the existing repertoire of Doppler assessments in placental insufficiency. The AoI is a link between the right and left ventricles which perfuse the lower and upper body, respectively. The clinical use of AoI waveforms for monitoring fetal deterioration in IUGR has been limited, but preliminary work suggests that abnormal AoI impedance indices are an intermediate step between placental insufficiency-hypoxemia and cardiac decompensation. Further prospective studies correlating AoI indices with arterial and venous Doppler indices and perinatal outcome are required before encorporating this index into clinical practice.

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“…Abnormal flow in the ductus venosus, i.e., increased pulsatility, absent forward flow, or reversed flow during the atrial contraction phase of cardiac cycle (Fig. 8) may be a sign of impaired diastolic function [159]. Presence of Fig.…”

Section: Fetal Arterial and Venous Circulation And Cardiac Performancementioning

confidence: 99%

The Fetal Cardiac Function

Acharya¹,

Räsänen²,

Kiserud³

et al. 2006

CCR

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Despite significant progress in the prenatal diagnosis of congenital heart disease and the postnatal management, the prenatal evaluation of fetal heart function remains difficult. The unique characteristics of the fetal circulation have a significant impact on its cardiac function. Commonly used physiological concepts about the function of the heart can be misleading when applied to the intrauterine situation. Most noninvasive parameters of cardiac function are not validated in the fetus. In addition, unlike structural defects that can be easily confirmed after delivery, functional hemodynamic abnormalities diagnosed in utero cannot be verified postnatally with certainty as the neonatal circulation defers considerably from the fetal circulation. This review attempts to describe commonly used methods of assessment of fetal cardiac function, their physiological basis and, their utility in clinical practice. THE FETAL CARDIAC FUNCTIONThe heart's main function is to deliver sufficient oxygenated blood to meet the metabolic requirements of the tissues [1]. The overall cardiac performance reflects the interaction of the heart, blood volume and blood vessels. The unique characteristics of the fetal circulation [2] have a significant impact on its cardiac function and distribution of cardiac output. The fetal circulation differs considerably from the adult and neonatal circulation. The placenta, a large extracorporal organ designed for disposal at birth, performs the functions of many organ systems in utero. Human placenta receives about 30% of the combined cardiac output [3,4] and the total peripheral resistance in the fetus is mainly determined by the placental-vascular resistance [5]. The placental volume blood flow normalized for fetal weight decreases with advancing gestation after 25 weeks [6].Both sides of the fetal heart under normal conditions have similar pressures [7] and work in parallel, and the fetal heart rate is much faster than the adult. As a result the weight-indexed combined cardiac output is higher in the fetus and the outputs of the left and right ventricles can be different. Right ventricular dominance develops towards term, and the output of the right ventricle constitutes about 60% of the combined cardiac output [8]. The parallel disposition of two ventricular pumps confers the aortic isthmus (Fig. 1), i.e. the vascular segment located between the origin of the left subclavian artery and the junction of the aorta with the ductus arteriosus, a special function of maintaining communication and balance between two parallel arterial outlets [9].The pulmonary circulation has a high vascular resistance and is sensitive to the changes in arterial pH and partial Fig. (1). Color Doppler image of fetal aorta demonstrating the isthmic area (arrow) and typical pulsed-wave (inverted) Doppler velocity waveforms (lower panel) obtained at the aortic isthmus in a near term fetus. A brief small reverse component during early diastole (arrow-head) is normal in late gestation.pressure of oxygen (PO 2 ) and carbon di...

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Fetal Venous Circulation

Cited by 22 publications

References 132 publications

Fetal Liver-Sparing Cardiovascular Adaptations Linked to Mother’s Slimness and Diet

Fetal Liver-Sparing Cardiovascular Adaptations Linked to Mother’s Slimness and Diet

Aortic isthmus Doppler velocimetry: role in assessment of preterm fetal growth restriction

The Fetal Cardiac Function

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