Fetal Coronary Arteries Research Articles

Color Doppler visualization of fetal coronary arteries is enhanced by high resolution and Radiantflow.

Color Doppler visualization of fetal coronary arteries is enhanced by high resolution and Radiantflow.

Micro-CT to study and reconstruct fetal and infant coronary arteries: a pilot study on a novel post-mortem technique

For a significant part of infant and fetal deaths, specific pathophysiologic processes cannot be recognized. Thus, the scientific community is called to identify novel post-mortem diagnostic tools. This manuscript proposes the results of a pilot study which reports a novel post-mortem technique to study and reconstruct fetal/ infant coronary arteries. The study included human fetuses characterized by the absence of macroscopic cardiac abnormalities at postmortem in situ examination. For the study of fetal hearts, it was used a curing radiopaque silicone rubber compound (which solidified after injection in the coronary arteries) and an X-Ray microtomography (micro-CT). After micro- CT scans, coronary arteries’ branches were reconstructed throughout a specific software. At injection, it was possible to macroscopically evaluate coronary arteries’ perfusion. The analysis of the three-dimensional reconstructions highlighted that the aforementioned compound reached deep branches too. This approach can be considered a novel post-mortem technique for fetal/infant hearts. Nevertheless, the manuscript also discussed the following limitations: in some spots, coronary arteries’ reconstruction appeared interrupted; the compound also perfused parts of internal cardiac chambers. Until now, in the literature there are not methods that allow study with reconstruction of fetal/infant coronary arteries throughout micro-CT. The present paper pointed out the first indications for the application of this technique in human samples.

Evolution of fetal cardiac imaging in 30 years of ISUOG.

Evolution of fetal cardiac imaging in 30 years of ISUOG.

Sapropterin reduces coronary artery malformation in offspring of pregestational diabetes mice

Endothelial nitric oxide synthase (eNOS) and oxidative stress are critical to embryonic coronary artery development. Maternal diabetes increases oxidative stress and reduces eNOS activity in the fetal heart. Sapropterin (Kuvan®) is an orally active, synthetic form of tetrahydrobiopterin (BH4) and a co-factor for eNOS with antioxidant properties. The aim of the present study was to examine the effects of sapropterin on fetal coronary artery development during pregestational diabetes in mice. Diabetes was induced by streptozotocin to adult female C57BL/6 mice. Sapropterin (10 mg/kg/day) was orally administered to pregnant mice from E0.5 to E18.5. Fetal hearts were collected at E18.5 for coronary artery morphological analysis. Sapropterin treatment to diabetic dams reduced the incidence of coronary artery malformation in offspring from 50.0% to 20.6%. Decreases in coronary artery luminal diameter, volume and abundance in fetal hearts from diabetic mothers, were prevented by sapropterin treatment. Maternal diabetes reduced epicardial epithelial-to-mesenchymal transition (EMT) and expression of transcription and growth factors critical to coronary artery development including hypoxia-inducible factor 1a (Hif1a), Snail1, Slug, β-catenin, retinaldehyde dehydrogenase 2 (Aldh1a2), basic fibroblast growth factor (bFGF) and vascular endothelial group factor receptor 2 (Vegfr2) in E12.5 hearts. Additionally, eNOS phosphorylation was lower while oxidative stress was higher in E12.5 hearts from maternal diabetes. Notably, these abnormalities were all restored to normal levels after sapropterin treatment. In conclusion, sapropterin treatment increases eNOS activity, lowers oxidative stress and reduces coronary artery malformation in offspring of pregestational diabetes. Sapropterin may have therapeutic potential in preventing coronary artery malformation in maternal diabetes.

OP15.09: The clinical value of echocardiography in diagnosis of fetal coronary artery compensatory dilatation

OP15.09: The clinical value of echocardiography in diagnosis of fetal coronary artery compensatory dilatation

Prominent coronary artery flow with normal coronary artery anatomy is a rare but ominous harbinger of poor outcome in the fetus

Objectives: “Heart sparing” refers to prominent antegrade fetal coronary artery (CA) blood flow readily visualized by color Doppler and is a harbinger of poor outcome in growth restricted fetus, but little is known of the features and presentation of heart sparing in normally grown fetuses. Our objective was to describe heart sparing effects in normally grown fetuses, and compare the presentation and outcome of heart sparing between fetuses with growth restriction and those who were normally grown.Methods: In a series of fetuses with prominent antegrade CA flow, we assessed Doppler flow profiles in the aortic isthmus, ductus venosus (DV), umbilical vein (UV), umbilical artery (UA) and middle cerebral artery (MCA). We calculated MCA and UA systolic/diastolic ratios and the cerebral placental ratio, and measured fetal biometry. We evaluated cardiac function using the myocardial performance index (MPI) and the cardiovascular profile score (CVPS).Results: Ten fetuses with heart sparing had normal DV flow at 24–36.6 (mean 30.9) weeks of gestation. Five had growth restriction (Group 1); 4/5 had normal MPI and CVPS, and one died. Five were normally grown (Group 2); 5/5 had elevated MPI and decreased CVPS, of these 2 died in utero and one died immediately after birth despite urgent delivery. Coronary arteries were normal after birth or autopsy.Conclusions: Heart sparing confers a poor prognosis in fetal growth restriction and in normally grown fetuses with cardiac dysfunction. We suggest CA flow be assessed in all high-risk fetuses.

Schild Analysis of In Vivo Theophylline Antagonism of Adenosine in Fetal Sheep Coronary Arteries

Adenosine causes near‐maximal vasorelaxation of fetal coronary arteries but adenosine receptor antagonism in this bed has not been characterized. We performed Schild analysis of theophylline (adenosine antagonist with similar affinity for receptors A1, A2a and A2b) in near‐term fetal sheep coronaries. Fetuses (n=4) were instrumented with vascular catheters and a circumflex transit‐time flow probe. Vascular pressures (corrected to amniotic pressure) and coronary flow (corrected to driving force) were recorded continuously. Heart rate was controlled with propranolol and atropine. Theophylline (bolus then continuous infusion) was given into the right atrium. Graded infusions of adenosine into the left atrium stimulated increased coronary flow. Theoretical adenosine concentrations were calculated from infusion rates and assumed left ventricular output; theophylline concentrations were measured in arterial blood. The plateau was constrained at 100% of adenosine‐stimulated coronary flow, while the floor was unconstrained, allowing for theophylline suppression of baseline flow due to endogenously produced adenosine. Log(EC50), pA2, Schild and Hill slopes were constrained to share values within one fetal experiment. Schild analysis yielded a mean global R2=0.98, EC50=0.88±0.41uM(sd), Hill slope=2.5±0.4, Schild slope=0.94±0.63 and pA2=4.8±0.4. A Schild slope close to 1 indicates theophylline acts as a competitive antagonist of adenosine in the fetal coronaries in this dose range, thus pA2=pKb. These data suggest that maternal methylxanthine consumption may alter fetal coronary perfusion.Supported by NICHD R01HD071068 and P01HD034430.

Maternal nutrient restriction during pregnancy impairs an endothelium-derived hyperpolarizing factor-like pathway in sheep fetal coronary arteries.

The mechanisms underlying developmental programming are poorly understood but may be associated with adaptations by the fetus in response to changes in the maternal environment during pregnancy. We hypothesized that maternal nutrient restriction during pregnancy alters vasodilator responses in fetal coronary arteries. Pregnant ewes were fed a control [100% U.S. National Research Council (NRC)] or nutrient-restricted (60% NRC) diet from days 50 to 130 of gestation (term = 145 days); fetal tissues were collected at day 130. In coronary arteries isolated from control fetal lambs, relaxation to bradykinin was unaffected by nitro-l-arginine (NLA). Iberiotoxin or contraction with KCl abolished the NLA-resistant response to bradykinin. In fetal coronary arteries from nutrient-restricted ewes, relaxation to bradykinin was fully suppressed by NLA. Large-conductance, calcium-activated potassium channel (BKCa) currents did not differ in coronary smooth muscle cells from control and nutrient-restricted animals. The BKCa openers, BMS 191011 and NS1619, and 14,15-epoxyeicosatrienoic acid [a putative endothelium-derived hyperpolarizing factor (EDHF)] each caused fetal coronary artery relaxation and BKCa current activation that was unaffected by maternal nutrient restriction. Expression of BKCa-channel subunits did not differ in fetal coronary arteries from control or undernourished ewes. The results indicate that maternal undernutrition during pregnancy results in loss of the EDHF-like pathway in fetal coronary arteries in response to bradykinin, an effect that cannot be explained by a decreased number or activity of BKCa channels or by decreased sensitivity to mediators that activate BKCa channels in vascular smooth muscle cells. Under these conditions, bradykinin-induced relaxation is completely dependent on nitric oxide, which may represent an adaptive response to compensate for the absence of the EDHF-like pathway.

Maternal nutrient restriction during pregnancy impairs an EDHF‐like pathway in fetal coronary arteries without affecting large conductance, calcium‐activated K channel (BKCa) activity in smooth muscle cells

We demonstrated previously that maternal nutrient restriction during pregnancy impairs an EDHF‐like pathway that is mediated via BKCa activation in fetal coronary arteries (CA). We now show that the impairment is not likely due to altered BKCa activity in CA smooth muscle cells. Pregnant ewes were fed a control or nutrient restricted diet from day 50–130 of gestation. In CA isolated from control fetal lambs, relaxation to bradykinin was partially inhibited by nitro‐l‐arginine (NLA). Iberiotoxin nearly abolished the NLA‐resistant response to bradykinin. In CA from undernourished animals, relaxation to bradykinin was fully suppressed by NLA. Whole‐cell BKCa currents were nearly identical in CA smooth muscle cells from control and nutrient restricted animals (peak current density= 46 ± 5 vs. 39 ± 6 pA/pF; n=6). 14,15‐EET (putative EDHF in CA) caused fetal CA relaxation and BKCa activation that was unaffected by maternal nutrient restriction. Similar results were obtained with the BKCa‐openers, BMS 191011 and NS 1619. Relaxation to bradykinin in fetal CA is mediated by NO, and by an EDHF‐like pathway that involves BKCa activation. Maternal undernutrition during pregnancy results in loss of the EDHF‐like pathway in fetal CA, an effect that is likely due to endothelial dysfunction (i.e. impaired synthesis and/or release of an EDHF‐like mediator) rather than impaired BKCa activity in CA smooth muscle cells. (NIH HD61532)

Decreased maternal dietary protein intake during pregnancy alters large conductance, calcium‐activated K channel (BKCa) function in fetal coronary artery smooth muscle cells

We have shown that maternal nutrient restriction during pregnancy impairs an EDHF‐like pathway that is mediated via BKCa activation in fetal coronary arteries (CA). We hypothesized that BKCa activity is altered in CA of fetuses from malnourished ewes. Pregnant ewes were fed diets that differed only in metabolizable protein levels (control = 100% vs low protein = 80% of NRC recommendation) from day 100 – 130 of gestation. Fetal CA were then harvested and whole‐cell K currents (−70 to +50mV, 200 ms duration) were obtained in freshly isolated smooth muscle cells (n = 5–6 cells/fetus). In fetal CA smooth muscle cells from ewes fed a low protein diet, the I‐V curve was shifted to the left and peak current density was increased by 31% (low protein = 92.3 ± 7.5 vs. control = 70.5 ± 6.8 pA/pF; n=14). Iberiotoxin (100 nM) almost completely inhibited the K current in cells from the low protein group (72.3 ± 4.8% inhibition), but only partially inhibited this current in controls (31.5 ± 6.2% inhibition). Expression and localization of BKCa α‐ and β1‐subunits was similar in CA from both groups. Restricted maternal protein intake during late pregnancy enhances BKCa activity in fetal CA, without altering BKCa expression or localization, and may represent an adaptation to the dysfunction in the coronary arterial EDHF‐like pathway previously observed in offspring of ewes subjected to decreased nutrient intake during pregnancy (NIH R03HD061532).

Feto-Placental Atherosclerotic Lesions in Intrauterine Fetal Demise: Role of Parental Cigarette Smoking

The atherogenic effect of cigarette smoking is already recognizable in coronary arteries of fetuses in the last gestational weeks. In this study we analyzed the atherogenic effect of mother’s and father’s smoking habit on coronary arteries and even on adnexa of 30 human fresh fetuses died from 32 to 41 gestational weeks. In 12 cases only the mothers of the victims were cigarette smokers, in 7 cases only the fathers were smokers, whereas in 11 cases nobody smoked.We observed pre-atherosclerotic and initial atherosclerotic lesions of the adnexa in 21 cases, of which 11 cases had only mother smokers and 6 cases only father smokers. The atherogenic effect is statistically significant in both smoker groups, but stronger in maternal one. The atherosclerotic lesions found in umbilical and placental arteries are similar to those described in fetal coronary arteries: thickening of the arterial walls caused by proliferation and migration of the smooth muscle cells of the tunica media with loss of polarity and infiltration of the subendothelial connective tissue.

An enhancement of coronary blood flow in a fetus with supraventricular tachycardia

Modern obstetric ultrasound has allowed a detailed evaluation of many fetal small arteries in both normal and abnormal conditions. Recently, a study of a very tiny fetal coronary artery has been proved possible when the imaging condition is optimal (Baschat et al., 1997). An augmentation of fetal coronary blood flow reflecting an attempt to compensate for an increase in oxygen demand by means of autoregulation process has been demonstrated with Doppler ultrasound in both acute and chronic fetal stress conditions such as acute fetomaternal hemorrhage, fetal ductal constriction, and intrauterine growth restriction (IUGR) (Baschat et al., 2003). We present herein the first case of coronary blood flow enhancement in a fetus with supraventricular tachycardia (SVT) demonstrated with Doppler ultrasound. The evidence of the enhancement of blood flow disappeared when the fetal heart rate was eventually converted to normal sinus rhythm with maternal ingestion of flecainide. A 26-year-old pregnant woman, gravida 1, was referred to our high-risk pregnancy clinic at 29 weeks’ gestation for a rapid fetal heart rate detected at prenatal clinic. Our sonographic examination revealed a fetal biometry consistent with gestational age. No structural anomaly was noted. Fetal echocardiography demonstrated a normal cardiac anatomy. A rapid heart rate of 220–240 bpm with 1-to-1 atrioventricular conduction was noted in M-mode. Color Doppler ultrasound clearly demonstrated a holosystolic tricuspid regurgitation and a prominent coronary blood flow (Figure 1a). Spectral Doppler showed an increased inferior vena cava (IVC) reversed flow at atrial contraction and an intact ductus venosus waveform. A biphasic coronary waveform with a diastolic peak flow of 45.5 cm/s was noted (Figure 1b). Fetal SVT was diagnosed and the fetus was initially treated with maternal ingestion of digoxin. The fetal heart rate resisted converting to sinus rhythm after 5 days when maternal digitalis level reached the therapeutic range of 1.2 ng/mL.Treatment was then switched

P45.13: Imaging of fetal coronary arteries and pulmonary veins with gray and color flow Doppler sonography

P45.13: Imaging of fetal coronary arteries and pulmonary veins with gray and color flow Doppler sonography

Differential Expression of Endothelial Nitric Oxide Synthase in Coronary and Cardiac Tissue in Hypoxic Fetal Guinea Pig Hearts

The purpose of the present study was to quantify the effect of chronic hypoxia on endothelial nitric oxide synthase (eNOS) gene and protein expression of fetal coronary artery segments and cardiac tissue of fetal guinea pig hearts. Time-mated pregnant guinea pigs (term = 65 days) were housed in room air (NMX, n = 6) or in a hypoxic chamber containing 10.5% O2 for 14 days (HPX14, n = 6). At near term (60 days gestation), fetuses were excised from anesthetized animals via hysterotomy and hearts were removed and weighed. Both coronary artery segments and cardiac ventricle were excised from the same hearts, frozen, and stored at -80 C until ready for study. eNOS mRNA was quantified using real-time polymerase chain reaction (PCR) based on SYBR Green I labeling (BioRad Laboratories, Hercules, CA) using eNOS primers obtained from GeneBank normalized to 18S. eNOS proteins were quantified by Western immunoblotting using eNOS antibody (1:200) and normalized to normoxic controls. eNOS cell-specific localization in the fetal guinea pig heart was performed by double immunofluorescence staining. Both coronary artery endothelial cells (EC) and cardiomyocytes (CM) but not vascular smooth muscle cells of normoxic hearts exhibited positive immunostaining of eNOS protein. Chronic hypoxia significantly (P < .05) increased both eNOS mRNA and protein levels of coronary artery segments (by 210.6% and 51.4%, respectively) but decreased (P < .05) mRNA and protein of cardiac tissue (by 50.0% and 40.6%, respectively) in the same hearts. Chronic fetal hypoxia, after 14 days, induces sustained changes in eNOS gene and eNOS protein expression that differ between coronary and cardiac tissue in the fetal guinea pig heart. This study suggests that while the functional roles of altered eNOS expression in hypoxic fetal hearts remain unclear, the site at which eNOS expression is altered may be important in the adaptive response of the fetal heart to hypoxia.

OC33.03: Early visualization of the fetal coronary arteries by four‐dimensional ultrasonography with B‐flow imaging and spatiotemporal image correlation (STIC)

OC33.03: Early visualization of the fetal coronary arteries by four‐dimensional ultrasonography with B‐flow imaging and spatiotemporal image correlation (STIC)

Childhood Infection and Endothelial Dysfunction

The prodromal stage of atherosclerotic lesions (known as lipidotic fatty streak accumulation) is already formed during human fetal development.1 Fatty streaks containing characteristic accumulations of lipids, lipid peroxidation products, and macrophages occur in the aorta of premature fetuses. Intimal thickening is also observed in fetal coronary arteries.2,3 During infancy, fatty streaks become increasingly prevalent, and some of them progress to advanced stages of atherosclerotic lesions.4–7 Once initiated, the progression of atherosclerosis is influenced by classic risk factors that promote vascular inflammation and plaque rupture. The observation that maternal hypercholesterolemia is associated with greatly enhanced fatty streak formation in fetal arteries1 indicates that hypercholesterolemia may play a pathogenic role in early fetal atherosclerotic lesions. Maternal hypercholesterolemia is also able to influence fetal sterol metabolism during pregnancy in animal models.8,9 Consistently, direct evidence for a causal role of maternal hypercholesterolemia and the involvement of oxidative stress has been obtained in a rabbit model10,11 and in LDL receptor–deficient mice.12 From a molecular standpoint, many signaling pathways are affected by increased oxidation of LDL or the intracellular formation of reactive oxygen species, and this phenomenon can be exacerbated by concomitant hypercholesterolemia.13 Interestingly, deletion of the p66 shc longevity gene reduces systemic and tissue oxidative stress, vascular cell apoptosis, and early atherogenesis in mice fed a very highly hypercholesterolemic diet.14 Finally, growing evidence in the literature suggests that vascular damage occurs early and is mediated by …

Coronary arteries in fetal life: physiology, malformations and the “heart‐sparing effect”

The present knowledge of coronary arteries in prenatal diagnosis is reviewed with a focus on three aspects: the physiology and visualization of coronary flow, malformations involving the coronary arteries, and the "heart-sparing effect". Visualization of coronary arteries in a healthy human fetus is possible in real-time and colour Doppler during the last 10 wk of gestation when ultrasound conditions are excellent. Visualization at an earlier gestational age (up to 13 wk) is feasible mainly in association with malformations and impending hypoxia. The main coronary malformations that can be visualized in utero are the ventriculo-coronary communications in fetuses with pulmonary atresia. In the last few years, interest has been focused on the "heart-sparing effect", defined as the increased perfusion of the coronary arteries in fetuses with severe growth restriction and abnormal Doppler velocimetry in the peripheral vessels. Increased perfusion detectable with colour and pulsed Doppler is a late sign of fetal compromise in hypoxaemia. It confirms animal experiments that have demonstrated dilatory reserves of the fetal coronary arteries under chronic hypoxaemia. The outcome of 21 fetuses showing the "heart-sparing effect" before 32 wk gestation was poor: nine fetuses died in utero and two after birth, the median weight at birth was 630 g. In summary, our knowledge of the coronary arteries in the fetus is based on the diagnostic means used in prenatal diagnosis. New information in this field may also contribute to a better understanding of coronary heart disease later in life.

Fetal cardiac and cerebrovascular acclimatization responses to high altitude, long-term hypoxia.

In response to high altitude long-term hypoxemia, the heart of fetal sheep shows a decrease in cardiac output that is secondary to a decrease in myocardial cell contractile function. The intracellular mechanisms responsible for these reductions might include reduced myofibrillar Mg(2+)-activated ATPase. There is also a decrease in beta(1)-adrenergic receptor stimulated augmentation of myocardial contraction. An overproduction of cAMP by beta(1)-adrenergic receptor stimulation, resulting in overphosphorylation of troponin I, may reduce calcium binding by troponin C. Fetal coronary arteries have a reduced contractile response to K(+) depolarization and a reduced sensitivity to a thromboxane A(2) receptor agonist-stimulated contraction. Cerebral arteries of adult sheep (but not the fetus) show decreased responses to both K(+)-depolarization and norepinephrine-induced contraction. Nonetheless, cerebral arteries in the long-term hypoxic fetus demonstrated a number of significant changes from control. For the cerebral arteries in general, high altitude hypoxia is associated with augmented or upregulation of presynaptic functions. In contrast, postsynaptic functions tend to be significantly depressed or downregulated. The results emphasize the role of high altitude, long-term hypoxemia in modulating adrenergic- and serotonergic-mediated signal transduction in the cerebral vasculature. They specifically highlight the significant differences in acclimatization responses between the fetus and adult.

Color and pulsed Doppler ultrasonography of the fetal coronary arteries: has the time come for its clinical application?

Color and pulsed Doppler ultrasonography of the fetal coronary arteries: has the time come for its clinical application?

Coronary artery blood flow velocities in various fetal conditions.

To determine fetal coronary artery peak blood flow velocities in normal and high-risk pregnancies. Coronary artery peak systolic and diastolic blood flow velocities were measured by pulsed-wave Doppler velocimetry after identification of the coronary arteries by color Doppler imaging. Peak blood velocities obtained from normal pregnancies were related to gestational age using linear regression analysis. Blood flow velocities in normal fetuses were compared to measurements obtained in various fetal conditions. In normal fetuses coronary artery blood flow was visualized at a median gestational age of 33 + 6 weeks; median systolic and diastolic peak blood flow velocities were 0.21 and 0.43 m/s, respectively, and showed no significant change with gestational age. In growth-restricted fetuses coronary artery blood flow was visualized significantly earlier in gestation (median 28 + 2 weeks); systolic and diastolic peak blood flow velocities were higher at 0.25 and 0.48 m/s, respectively (P < 0.05). The highest coronary blood flow velocities were observed with fetal anemia. Coronary artery blood flow was also measured in fetuses with ductus arteriosus constriction due to indomethacin. Velocities did not differ from normal fetuses. Both in fetal anemia and ductus arteriosus constriction coronary artery blood flow could no longer be visualized with resolution of the underlying condition. Examination of coronary artery blood flow dynamics in the human fetus demonstrates acute increases in diastolic velocities in severe anemia and ductus arteriosus constriction based on the severity of the condition. In fetuses with growth restriction increased coronary blood flow velocities can be appreciated throughout the cardiac cycle. Clinical correlation in the interpretation of coronary blood flow dynamics in the human fetus is essential.