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Fetal Growth Restriction
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Juliana Gevaerd Martins, Alfred Abuhamad
Fetal circulation allows preferential distribution of nutrients in the fetus – nutrient- and oxygen-rich blood enters the circulation via the umbilical vein. The ductus venosus (DV) is the vascular shunt that modulates the proportion of umbilical venous blood that is distributed to the liver and heart. The direction and velocity of the blood coming from the DV to the right atrium, ensures preferential streaming of nutrient-rich blood to the left ventricle, myocardium and brain [54].
Fetal echocardiography
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Caroline K. Lee, Erik C. Michelfelder, Gautam K. Singh
In the normal four-chamber view, the RA and left atrium (LA) are approximately equal in size, and the RV and left ventricle (LV) are also approximately equal in size and thickness, with the RV becoming slightly larger than the LV as gestation progresses (14). The LA is the most posterior cardiac chamber and lies anterior to the descending aorta. The flap of the foramen ovale (septum primum) moves from the RA into LA, billowing about half-way into the LA, consistent with the right-to-left direction of foramen ovale flow in fetal circulation. The RV is the most anterior cardiac chamber and sits just posterior to the sternum. The LV cavity comprises the cardiac apex. The RV can be identified by the moderator band that courses across the lower part of the RV, from the interventricular septum to the RV free wall. The RV is also identified by the tricuspid valve that inserts into it. The atrioventricular valves are slightly offset from each other, with the tricuspid valve attaching slightly more apically than the mitral valve. From the four-chamber view, a posterior sweep will show the coronary sinus, which should be a thin structure that courses within the LA (Fig. 5). A dilated coronary sinus is seen when a persistent left superior vena cava (SVC) or anomalous pulmonary veins are present.
Abdominal surgery: General principles of access
Published in Mark Davenport, James D. Geiger, Nigel J. Hall, Steven S. Rothenberg, Operative Pediatric Surgery, 2020
Nigel J. Hall, Katherine A. Barsness
Special consideration is required for umbilical access in neonates and infants less than 1 year of age. During fetal circulation, the umbilical vein drains through the ductus venosus into the left hepatic vein, near its junction with the inferior vena cava. After birth, involution of the umbilical vein forms the falciform ligament. However, the age at which the natural patency of the remnant umbilical vein fully closes is not clearly defined. A number of case reports in the medical literature, as well as case law from malpractice lawsuits, document air embolism through the umbilical vein remnant to be a highly morbid or lethal complication of laparoscopy in infants. For this reason, both supraumbilical access and direct access through the center of the umbilicus should absolutely be avoided in neonates and infants. While the vast majority of air embolisms are noted to occur in infants of less than 3 months of age, the timing of full involution of the natural patency is not known. It should also be noted that air embolisms have been documented in cases when insufflation has not yet begun, hypothesized to be secondary to pushing air into the vein during advancement of a sheathed trocar into its Veress needle-placed sheath. Air embolism has also occurred at later stages of a procedure, when a trocar is either intentionally or inadvertently pulled back in the fascia, with resultant insufflation of the umbilical vein. As there is no absolutely safe method to place a trocar near the umbilical vein, it is therefore advised that all neonate and infant trocars be placed in an infraumbilical location.
Coronary Sinus Defect, Premature Restriction of Foramen Ovale and Cysto-Colic Peritoneal Band
Published in Fetal and Pediatric Pathology, 2023
The foramen ovale, a transitory atrial septum aperture that allows shunting of oxygenated placental blood to the left side of the heart and into systemic fetal circulation, is formed during the fourth week of gestation [10]. In most instances, the foramen ovale closes at birth or within the first three 3months of life [10]. Premature restriction or closure of foramen ovale, first described by Hansmann and Redel [11], is a deleterious condition occurring either as an isolated defect or in association with other congenital and cardiovascular anomalies [10]. As an isolated defect, restricted foramen ovale was identified in 23 cases by Uzun et al [12] who examined 1682 fetuses ultrasonographically, reporting an overall frequency of 1.4% [12]. All the restricted foramen ovale cases except for two were reported alive (21/1682 = 1.24%). Premature restriction or closure of foramen ovale in association with other anomalies was evaluated in an autopsy series by Levy et al [13] who analyzed 1,150 cases of congenital heart disease and found 10 with premature restriction/closure of foramen ovale reporting a frequency of 0.8%. While, Naeye and Blanc [14] reported 12 cases of prenatal narrowing or closure of the foramen ovale in their autopsy series, most other reports are anecdotal [15]. Literature suggests that majority of premature restriction or closure of foramen ovale are associated with hypoplastic left heart syndrome [3].
A Case of Transient Visual Field Defect following Administration of Pfizer-BioNTech COVID-19 Vaccine
Published in Ocular Immunology and Inflammation, 2022
Almila Sarıgül Sezenöz, Sirel Gür Güngör, Seda Kibaroğlu
Patent foramen ovale is a remnant of the fetal circulation, which normally closes within the first year of life. However, being the most common congenital heart defect, it persists as a cardiac communication between the left and right atria in 20% to 30% of the general adult population. In most people, it remains asymptomatic and therefore unnoticed for life.17 However, studies have shown that there is a possible connection with PFO and migraine and embolic events.17 In our case, our patient had a small PFO. The imaging studies we ran did not show any evidence of a possible embolus that might have predisposed by the presence of PFO. Therefore, we do not think that the patients’ complaints were directly linked to the PFO. Also, our patient has no personal or family history of migraine or aura before or after, and the one we report is the only episode, which has very close time link to vaccination. Also, the visual complaints of the patient lasted longer than a usual migraine aura. Based on these, we think that aura without migraine type headache or retinal migraine are less likely diagnoses in our case.
A narrative review of converging evidence addressing developmental toxicity of pyrethroid insecticides
Published in Critical Reviews in Toxicology, 2022
Benjamin A. Elser, Benjamin Hing, Hanna E. Stevens
Overall, there is limited evidence supporting the significant transfer of pyrethroids into fetal tissue. In general, studies investigating levels in cord blood do suggest some transfer to fetal circulation. However, they are unclear about the degree to which this transfer happens. In addition, many of these studies only investigated the type I pyrethroid permethrin, and as such, there is arguably the most robust evidence for placental transfer of permethrin, specifically, but the type II pyrethroid cypermethrin also was detected in some studies, albeit at low levels. However, studies investigating levels in meconium, which may represent accumulated exposure to pyrethroids, have found that over 90% of the time, levels are below the limit of detection for most pyrethroids and their metabolites assessed. Overall, a potential limitation of many of these studies is the generally low detection rates in both maternal and fetal samples, which may represent either low exposure/transfer or technical failure. Furthermore, studies that include both maternal and fetal blood measurements did not assess correlations between maternal and fetal pyrethroid levels for individual dyads likely due to limited sample numbers, which would provide additional data on the degree of transfer. An inherent limitation in these studies is the time-locked nature of fetal sample availability at the time of birth which may not reflect exposure/transfer at other time points. As such, it remains unclear as to the degree to which these compounds may enter fetal circulation to exert direct effects on fetal development in humans.