Changes in structural brain development after selective fetal growth restriction in monochorionic twins

OBJECTIVES

Fetal growth restriction (FGR) may alter brain development permanently, resulting in lifelong structural and functional changes. However, in studies addressing this research question, FGR singletons have been compared primarily to matched appropriately grown singletons, a design which is inherently biased by differences in genetic and maternal factors. To overcome these limitations, we conducted a within-pair comparison of neonatal structural cerebral ultrasound measurements in monochorionic twin pairs with selective FGR (sFGR).

METHODS

Structural cerebral measurements on neonatal cerebral ultrasound were compared between the smaller and larger twins of monochorionic twin pairs with sFGR, defined as a birth-weight discordance (BWD) ≥ 20%, born in our center between 2010 and 2020. Measurements from each twin pair were also compared with those of an appropriately grown singleton, matched according to sex and gestational age at birth.

RESULTS

Included were 58 twin pairs with sFGR, with a median gestational age at birth of 31.7 (interquartile range, 29.9-33.8) weeks and a median birth weight of 1155 g for the smaller twin and 1725 g for the larger twin (median BWD, 32%). Compared with both the larger twin and the singleton, the smaller twin had significantly smaller cerebral structures (corpus callosum, vermis, cerebellum), less white/deep gray matter and smaller intracranial surface area and volume. Intracranial-volume discordance and BWD correlated significantly (R²  = 0.228, P < 0.0001). The median intracranial-volume discordance was smaller than the median BWD (19% vs 32%, P < 0.0001). After correction for intracranial volume, only one of the observed differences (biparietal diameter) remained significant for the smaller twin vs both the larger twin and the singleton.

CONCLUSIONS

In monochorionic twins with sFGR, neonatal cerebral ultrasound reveals an overall, proportional restriction in brain growth, with smaller cerebral structures, less white/deep gray matter and smaller overall brain-size parameters in the smaller twin. There was a positive linear relationship between BWD and intracranial-volume discordance, with intracranial-volume discordance being smaller than BWD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Umbilical blood flow patterns directly after birth before delayed cord clamping

BACKGROUND

Delayed umbilical cord clamping (DCC) affects the cardiopulmonary transition and blood volume in neonates immediately after birth. However, little is known of blood flow in the umbilical vessels immediately after birth during DCC. The objective is to describe the duration and patterns of blood flow through the umbilical vessels during DCC.

METHODS

Arterial and venous umbilical blood flow was measured during DCC using Doppler ultrasound in uncomplicated term vaginal deliveries. Immediately after birth, the probe was placed in the middle of the umbilical cord, pattern and duration of flow in vein and arteries were evaluated until cord clamping.

RESULTS

Thirty infants were studied. Venous flow: In 10% no flow was present, in 57% flow stopped at 4:34 (3:03-7:31) (median (IQR) min:sec) after birth, before the cord was clamped. In 33%, flow continued until cord clamping at 5:13 (2:56-9:15) min:sec. Initially, venous flow was intermittent, increasing markedly during large breaths or stopping and reversing during crying, but then became continuous. Arterial flow: In 17% no flow was present, in 40% flow stopped at 4:22 (2:29-7:17) min:sec, while cord pulsations were still palpable. In 43% flow continued until the cord was clamped at 5:16 (3:32-10:10) min:sec. Arterial flow was pulsatile, unidirectional towards placenta or bidirectional to/from placenta. In 40% flow became continuous towards placenta later on.

CONCLUSIONS

During delayed umbilical cord clamping, venous and arterial umbilical flow occurs for longer than previously described. Net placental transfusion is probably the result of several factors of which breathing could play a major role. Umbilical flow is unrelated to cessation of pulsations.

[Treatment of foetal supraventricular tachycardia with antiarrhythmic medication administered through the umbilical vein]

Foetal supraventricular tachycardia (SVT) with hydrops foetalis is associated with a high morbidity and mortality rate. If SVT with hydrops foetalis persists despite transplacental therapy, direct foetal treatment can be initiated. One foetus was found to have SVT with hydrops foetalis during the 29th week of pregnancy, and the condition persisted despite transplacental treatment. Amiodarone was administered directly via the umbilical vein, and the SVT resolved. A second foetus was found to have SVT with hydrops foetalis during the 28th week of pregnancy. The condition persisted despite maternal antiarrhythmic medication. Direct treatment of the foetus with amiodarone was successful. Amiodarone is the treatment of choice for direct foetal therapy for SVT, and can be administered safely via the umbilical vein. Direct foetal therapy should be considered for the treatment of foetal SVT with hydrops foetalis that occurs in the first 31 weeks of pregnancy and persists despite adequate transplacental therapy.

[Diagnostic image (293). A neonate with a mass in the umbilical cord]

A term newborn girl had a mass at the base of the umbilical cord due to an umbilical cord hernia.

[Diagnostic image (245). A 2-year-old boy with an acute abdomen]

A 2-year-old boy presented at the emergency room with a surgical abdomen and respiratory and circulatory insufficiency caused by a volvulus of the short bowel around a string from a Meckel's diverticulum.

Cardiovascular response to physical exercise in adult patients after atrial correction for transposition of the great arteries assessed with magnetic resonance imaging

OBJECTIVE

To assess with magnetic resonance imaging (MRI) cardiovascular function in response to exercise in patients after atrial correction of transposition of the great arteries (TGA).

METHODS

Cardiac function at rest and during submaximal exercise was assessed with MRI in 27 patients with TGA (mean (SD) age 26 (5) years) late (23 (2) years) after atrial correction and in 14 control participants (25 (5) years old).

RESULTS

At rest, only right ventricular ejection fraction was significantly lower in patients than in controls (56 (7)% v 65 (7)%, p < 0.05). In response to exercise, increases in right ventricular end diastolic (155 (55) ml to 163 (57) ml, p < 0.05) and right ventricular end systolic volumes (70 (34) ml to 75 (36) ml, p < 0.05) were observed in patients. Furthermore, right and left ventricular stroke volumes and ejection fraction did not increase significantly in patients. Changes in right ventricular ejection fraction with exercise correlated with diminished exercise capacity (r = 0.43, p < 0.05).

CONCLUSIONS

In patients with atrially corrected TGA, MRI showed an abnormal response to exercise of both systemic right and left ventricles. Exercise MRI provides a tool for close monitoring of cardiovascular function in these patients, who are at risk for late death.

ECG predictors of ventricular arrhythmias and biventricular size and wall mass in tetralogy of Fallot with pulmonary regurgitation

BACKGROUND

In patients with the tetralogy of Fallot, QRS prolongation predicts malignant ventricular arrhythmias. QRS prolongation may result from right ventricular dilatation. The relation of ECG markers to biventricular wall mass and volumes has not been assessed.

OBJECTIVE

To investigate the relations of surface ECG markers of depolarisation and repolarisation to right and left ventricular volume and biventricular wall mass.

METHODS

37 Fallot patients (mean (SD) age 17 (9) years) were studied 14 (8) years after surgical repair; 34 had important pulmonary regurgitation. Left and right ventricular size was assessed from tomographic magnetic resonance imaging (MRI), and the amount of pulmonary regurgitation by velocity mapping MRI. QT, QRS, and JT duration and interlead dispersion markers were derived from a standard 12 lead ECG.

RESULTS

Mean QRS duration was significantly prolonged (133 (31) v 91 (11) ms in controls), as were dispersion of QRS (36 (17) v 20 (6) ms), QT interval (87 (48) v 42 (20) ms), and JT interval (93 (48) v 42 (19) ms). Biventricular volumes were increased (right ventricular end diastolic volume, 129 (41) v 70 (9) ml/m(2); left ventricular end diastolic volume, 83 (16) v 69 (10) ml/m(2)), as was right ventricular wall mass (24 (7) v 17 (2) g/m(2)). QRS duration correlated best with right ventricular mass (r = 0.55, p < 0.01).

CONCLUSIONS

In patients operated on for tetralogy of Fallot and with pulmonary regurgitation, ECG predictors of ventricular arrhythmias are influenced by several mechanical factors that may occur simultaneously. These include increased right ventricular volume, but also increases in left ventricular volume and in right and left ventricular wall mass.