Determinants of Increased Left Ventricular Output during In Utero Ventilation in Fetal Sheep

Lewinsky, Reuven M.; Szwarc, Richard S.; Benson, Lee; Ritchie, J. W. K.

doi:10.1203/00006450-199409000-00018

Cited by 4 publications

(5 citation statements)

References 31 publications

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“…Just before lung ventilation (90% of incubation, or day 19) the E A /E LV ratio is 1 in the normoxia-incubated chicken fetus (Table 3), which is similar to normal values in healthy adult mammals at rest and in fetal lambs (7,25). This suggests that mechanical efficacy and energetic efficiency are balanced similarly in fetal chickens as in adult and fetal mammals.…”

Section: Arterial-cardiac Couplingsupporting

confidence: 61%

Effects of chronic hypoxia on cardiac function measured by pressure-volume catheter in fetal chickens

Jonker

Giraud

Espinoza

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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Hypoxia is a common component of many developmental insults and has been studied in early-stage chicken development. However, its impact on cardiac function and arterial-ventricular coupling in late-stage chickens is relatively unknown. To test the hypothesis that hypoxic incubation would reduce baseline cardiac function but protect the heart during acute hypoxia in late-stage chickens, white Leghorn eggs were incubated at 21% O2 or 15% O2. At 90% of incubation (19 days), hypoxic incubation caused growth restriction (-20%) and increased the LV-to-body ratio (+41%). Left ventricular (LV) pressure-volume loops were measured in anesthetized chickens in normoxia and acute hypoxia (10% O2). Hypoxic incubation lowered the maximal rate of pressure generation (ΔP/ΔtMax; -22%) and output (-57%), whereas increasing end-systolic elastance (ELV; +31%) and arterial elastance (EA; +122%) at similar heart rates to normoxic incubation. Both hypoxic incubation and acute hypoxia lengthened the half-time of relaxation (τ; +24%). Acute hypoxia reduced heart rate (-8%) and increased end-diastolic pressure (+35%). Hearts were collected for mRNA analysis. Hypoxic incubation was marked by decreased mRNA expression of sarco(endo)plasmic reticulum Ca(2+)-ATPase 2, Na(+)/Ca(2+) exchanger 1, phospholamban, and ryanodine receptor. In summary, hypoxic incubation reduces LV function in the late-stage chicken by slowing pressure generation and relaxation, which may be driven by altered intracellular excitation-contraction coupling. Cardiac efficiency is greatly reduced after hypoxic incubation. In both incubation groups acute hypoxia reduced diastolic function.

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Section: Arterial-cardiac Couplingsupporting

confidence: 61%

Effects of chronic hypoxia on cardiac function measured by pressure-volume catheter in fetal chickens

Jonker

Giraud

Espinoza

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Second, inspiration in human fetuses [6] and intrauter ine ventilation in fetal lambs [3,5,7] are associated with an increase in left ventricular stroke volume. Such an increase can be due to an increase in ejection fraction, end-diastolic volume, or both.…”

Section: Discussionmentioning

confidence: 99%

“…An increase in ejection fraction may be caused by an increase in contractility or a reduction in afterload. However, afterload actually in creases during respiration [3], and contractility does not change at a time when left ventricular output almost dou bles [7], Therefore, the ejection fraction does not seem to change during respiration, so that the inspiration-associ ated increase in stroke volume is likely to be caused by an increase in left ventricular end-diastolic volume.…”

Section: Discussionmentioning

confidence: 99%

“…This observation has been traditionally attributed to poor compliance of the fetal heart owing to an inherent immaturity of the cardiac myocytes [4], However, human and animal experiments have demonstrated that fetal left ventricular stroke volume increases during in utero venti lation and spontaneous breathing activity [3,[5][6][7], The mechanisms underlying this phenomenon have not been established. The increased stroke volume occurs despite an increase in left ventricular afterload, is not reduced by P-adrenergic blockade, and cannot be reproduced by increasing filling pressure before ventilation.…”

Section: Introductionmentioning

confidence: 99%

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Fetal Breathing Movements Are Associated with Changes in Compliance of the Left Ventricle

Miyague¹,

Ghidini²,

Miyague³

1997

Fetal Diagn Ther

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We have tested the hypothesis that the limited fetal ventricular distensibility is not only an intrinsic cardiac characteristic but is also contributed to by the pressure exerted by the intrathoracic organs. To this purpose we have studied the diastolic cardiac function by Doppler velocimetry in 11 fetuses during fetal breathing and in 22 fetuses during apnea, controlling for gestational age at examination and heart rate. Inspiration was associated with a significant increase in left ventricular compliance, as measured by deceleration time (inspiration 182.6 ± 15.5 s vs. expiration 137.1 ± 13.1 s vs. apnea 151.7 ± 51.8 s), and in ventricular filling, as measured by velocity time integral (inspiration 0.086 ± 0.020 m vs. expiration 0.064 ± 0.014 m vs. apnea 0.065 ± 0.011m), compared with both the expiration and apnea groups. These increases most likely reflect changes in venous return and ventricular end-diastolic volume secondary to a decrease in intrathoracic pressue during fetal breathing.

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“…With parallel circulation, fetal hemodynamics are distinct from their postnatal occurrences (6). Several studies indicated the fetal ventricle is sensitive to cardiac load changes (7,8). Obstruction to cardiac outflow in fetuses with TOF might ultimately lead to myocardial impairment in utero and may also influence the postnatal outcome and interventional timing.…”

Section: Introductionmentioning

confidence: 99%

Ventricular Myocardial Deformation in Fetuses With Tetralogy of Fallot: A Necessary Field of Investigation

Song

Luan

Zhang

et al. 2021

Front. Cardiovasc. Med.

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Background: Tetralogy of Fallot (TOF) is one of the most common cyanotic congenital heart defects (CHDs). The patterns of fetal myocardial deformations in TOF have not been well-studied. This study aimed to assess biventricular myocardial deformations in fetuses with TOF compared with normal fetuses.Methods: A retrospective cohort study of fetuses with TOF and gestational age (GA)-matched controls was conducted at a single tertiary referral center from 2014 to 2020. All enrolled fetuses underwent detailed echocardiography, and four-chamber video-clips were recorded and analyzed offline for deformation assessment by using two-dimensional speckle tracking echocardiography (2D-STE). Comparisons for baseline characteristics, cardiac morphological measurements (ventricular, atrial, and great arterial diameters or ratios, global sphericity index), systolic function parameters [ejection fraction (EF), fractional area change (FAC)], and strain parameters [global longitudinal strain (GLS), global longitudinal strain rate in systole and diastole (GLSRs, GLSRd)] were performed between fetuses with TOF and GA-matched controls.Results: Fifty-two fetuses with TOF and 52 GA-matched controls were enrolled in this study. Fetuses with TOF exhibited similar left ventricular (LV) EF (58.51 ± 5.11% vs. 57.59 ± 5.38%, P = 0.16) and right ventricular (RV) FAC (43.64 ± 2.89% vs. 44.27 ± 3.04%, P = 0.25), compared to normal fetuses. While, in deformational analysis, TOF fetuses demonstrated significantly lower LV and RV GLS values (−22.57 ± 2.91% vs. −27.39 ± 4.38%, P < 0.001 for LV GLS; −24.27 ± 3.18% vs. −28.71 ± 4.48%, P < 0.001 for RV GLS). Both LV GLS (r = −0.518, P < 0.001) and RV GLS (r = −0.534, P < 0.001) were found negatively correlated with the aortic valve-to-pulmonary valve diameter ratio (AV:PV ratio). Z-scores of PV annulus and main pulmonary artery (MPA) also had positive correlation with LV and RV GLS, respectively.Conclusions: Decreased biventricular myocardial deformations can appear even in fetuses with TOF with normal systolic ventricular function. Both LV and RV GLS values are correlated with the severity of right ventricular outflow tract obstruction. It indicates 2D-STE may be a more sensitive tool to assess fetal cardiac function than the conventional echocardiographic methods.

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Determinants of Increased Left Ventricular Output during In Utero Ventilation in Fetal Sheep

Cited by 4 publications

References 31 publications

Effects of chronic hypoxia on cardiac function measured by pressure-volume catheter in fetal chickens

Effects of chronic hypoxia on cardiac function measured by pressure-volume catheter in fetal chickens

Fetal Breathing Movements Are Associated with Changes in Compliance of the Left Ventricle

Ventricular Myocardial Deformation in Fetuses With Tetralogy of Fallot: A Necessary Field of Investigation

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