Background: Brain injury, impaired brain growth, and long-term neurodevelopmental problems are common in children with transposition of the great arteries. We sought to identify clinical risk factors for brain injury and poor brain growth in infants with transposition of the great arteries undergoing the arterial switch operation, and to examine their relationship with neurodevelopmental outcome. Methods: The brains of 45 infants with transposition of the great arteries undergoing surgical repair were imaged pre- and postoperatively using magnetic resonance imaging. Brain weight z scores were calculated based on brain volume and autopsy reference data. Brain injury scores were determined as previously described. Neurodevelopment was assessed at 18 months using the Bayley-III scores of infant development. The relationships between clinical variables, brain injury, perioperative brain growth, and 18-month Bayley-III scores were analyzed. Results: On preoperative imaging, moderate or severe white matter injury was present in 10 of 45 patients, whereas stroke was seen in 4 of 45. A similar prevalence of injury was seen on postoperative imaging, and we were unable to identify any clinical risk factors for brain injury. Brain weight z scores decreased perioperatively in 35 of 45 patients. The presence of a ventricular septal defect ( P =0.009) and older age at surgery ( P =0.007) were associated with impaired perioperative brain growth. When patients were divided into those undergoing surgery during the first 2 weeks of life (32/45) versus those being repaired later (13/45), infants repaired later had significantly worse perioperative brain growth (late repair postoperative brain weight z = –1.0±0.90 versus early repair z = –0.33±0.64; P =0.008). Bayley-III testing scores fell within the normal range for all patients, although age at repair ( P =0.03) and days of open chest ( P =0.03) were associated with a lower composite language score, and length of stay was associated with a lower composite cognitive score ( P =0.02). Conclusions: Surgery beyond 2 weeks of age is associated with impaired brain growth and slower language development in infants with transposition of the great arteries cared for at our center. Although the mechanisms underlying this association are still unclear, extended periods of cyanosis and pulmonary overcirculation may adversely impact brain growth and subsequent neurodevelopment.

64-slice CT coronary angiography performs as well as invasive angiography for detecting significant coronary lesions in the majority of children who have undergone the arterial switch procedure for TGA. CT also provides information on the underlying mechanism of coronary luminal narrowing.

Objectives To determine prevalence and risk factors for brain injury in infants with critical congenital heart disease (CHD) from 2 sites with different practice approaches who were scanned clinically. Study design Prospective, longitudinal cohort study (2016-2017) performed at Hospital for Sick Children Toronto (HSC) and Wilhelmina Children's Hospital Utrecht (WKZ), including 124 infants with cardiac surgery £60 days (HSC = 77; WKZ = 47). Magnetic resonance imaging was performed per clinical protocol, preoperatively (n = 100) and postoperatively (n = 120). Images were reviewed for multifocal (watershed, white matter injury) and focal ischemic injury (stroke, single white matter lesion). Results The prevalence of ischemic injury was 69% at HSC and 60% at WKZ (P = .20). Preoperative multifocal injury was associated with low cardiac output syndrome (OR, 4.6), which was equally present at HSC and WKZ (20% vs 28%; P = .38). Compared with WKZ, HSC had a higher prevalence of balloon-atrioseptostomy in transposition of the great arteries (83% vs 53%; P = .01) and more frequent preoperative focal injury (27% vs 6%; P = .06). Postoperatively, 30% of new multifocal injury could be attributed to postoperative low cardiac output syndrome, which was equally present at HSC and WKZ (38% vs 28%; P = .33). Postoperative focal injury was associated with intraoperative selective cerebral perfusion in CHD with arch obstruction at both sites (OR, 2.7). Compared with HSC, WKZ had more arch obstructions (62% vs 35%; P < .01) and a higher prevalence of new focal injury (36% vs 16%; P = .01). Conclusions Brain injury is common in clinical cohorts of infants with critical CHD and related to practice approaches. This study confirms that the high prevalence of brain injury in critical CHD is a clinical concern and does not simply reflect the inclusion criteria of published research studies.

PurposeTo image multidimensional flow in fetuses using golden-angle radial phase contrast cardiovascular magnetic resonance (PC-CMR) with motion correction and retrospective gating.MethodsA novel PC-CMR method was developed using an ungated golden-angle radial acquisition with continuously incremented velocity encoding. Healthy subjects (n = 5, 27 ± 3 years, males) and pregnant females (n = 5, 34 ± 2 weeks gestation) were imaged at 3 T using the proposed sequence. Real-time reconstructions were first performed for retrospective motion correction and cardiac gating (using metric optimized gating, MOG). CINE reconstructions of multidimensional flow were then performed using the corrected and gated data.ResultsIn adults, flows obtained using the proposed method agreed strongly with those obtained using a conventionally gated Cartesian acquisition. Across the five adults, bias and limits of agreement were − 1.0 cm/s and [− 5.1, 3.2] cm/s for mean velocities and − 1.1 cm/s and [− 6.5, 4.3] cm/s for peak velocities. Temporal correlation between corresponding waveforms was also high (R~ 0.98). Calculated timing errors between MOG and pulse-gating RR intervals were low (~ 20 ms). First insights into multidimensional fetal blood flows were achieved. Inter-subject consistency in fetal descending aortic flows (n = 3) was strong with an average velocity of 27.1 ± 0.4 cm/s, peak systolic velocity of 70.0 ± 1.8 cm/s and an intra-class correlation coefficient of 0.95 between the velocity waveforms. In one fetal case, high flow waveform reproducibility was demonstrated in the ascending aorta (R = 0.97) and main pulmonary artery (R = 0.99).ConclusionMultidimensional PC-CMR of fetal flow was developed and validated, incorporating retrospective motion compensation and cardiac gating. Using this method, the first quantification and visualization of multidimensional fetal blood flow was achieved using CMR.Electronic supplementary materialThe online version of this article (10.1186/s12968-018-0498-z) contains supplementary material, which is available to authorized users.

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Sharper angulation of the aortic arch is associated with early pulse wave reflection, dilatation of the ascending aorta, and aortic regurgitation late after the arterial switch operation for transposition of the great arteries.

Magnetic resonance imaging (MRI) is an appealing technology for fetal cardiovascular assessment. It can be used to visualize fetal cardiac and vascular anatomy, to quantify fetal blood flow, and to quantify fetal blood oxygen saturation and hematocrit. However, there are practical limitations to the use of conventional MRI for fetal cardiovascular assessment, including the small size and high heart rate of the human fetus, the lack of conventional cardiac gating methods to synchronize data acquisition, and the potential corruption of MRI data due to maternal respiration and unpredictable fetal movements. In this review, we discuss recent technical advances in accelerated imaging, image reconstruction, cardiac gating, and motion compensation that have enabled dynamic MRI of the fetal heart.

Key points Human placental function is evaluated using non‐invasive Doppler ultrasound of umbilical and uterine artery pulsatility indices as measures of resistance in placental vascular beds, while measurement of placental oxygen consumption (VnormalO2) is only possible during Caesarean delivery. This study shows the feasibility of using magnetic resonance imaging (MRI) in utero to measure blood flow and oxygen content in uterine and umbilical vessels to calculate oxygen delivery to and VnormalO2 by the gravid uterus, uteroplacenta and fetus. Normal late gestational human uteroplacental VnormalO2 by MRI was ∼4 ml min−1 kg−1 fetal weight, which was similar to our MRI measurements in sheep and to those previously measured using invasive techniques. Our MRI approach can quantify uteroplacental VnormalO2, which involves the quantification of maternal‐ and fetal‐placental blood flows, fetal oxygen delivery and VnormalO2, and the oxygen gradient between uterine‐ and umbilical‐venous blood, providing a comprehensive assessment of placental function with clinical potential. Abstract It has not been feasible to perform routine clinical measurement of human placental oxygen consumption (VnormalO2) and in vitro studies do not reflect true metabolism in utero. Here we propose an MRI method to non‐invasively quantify in utero placental and fetal oxygen delivery (DnormalO2) and VnormalO2 in healthy humans and sheep. Women (n = 20) and Merino sheep (n = 10; 23 sets of measurements) with singleton pregnancies underwent an MRI in late gestation (36 ± 2 weeks and 128 ± 9 days, respectively; mean ± SD). Blood flow (phase‐contrast) and oxygen content (T1 and T2 relaxometry) were measured in the major uterine‐ and umbilical‐placental vessels, allowing calculation of uteroplacental and fetal DnormalO2 and VnormalO2. Maternal DnormalO2 (ml min−1 kg−1 fetus) to the gravid uterus was similar in humans and sheep (human = 54 ± 15, sheep = 53 ± 21, P = 0.854), while fetal DnormalO2 (human = 25 ± 4, sheep = 22 ± 5, P = 0.049) was slightly lower in sheep. Uteroplacental and fetal VnormalO2 (ml min−1 kg−1 fetus; uteroplacental: human = 4.1 ± 1.5, sheep = 3.5 ± 1.9, P = 0.281; fetus: human = 6.8 ± 1.3, sheep = 7.2 ± 1.7, P = 0.426) were similar between species. Late gestational uteroplacental:fetal VnormalO2 ratio did not change with age (human, P = 0.256; sheep, P = 0.121). Human umbilical blood flow (ml min−1 kg−1 fetus) decreased with advancing age (P = 0.008), while fetal VnormalO2 was preserved through an increase in oxygen extraction (P = 0.046). By contrast, sheep fetal VnormalO2 was preserved through stable umbilical flow (ml min−1 kg−1; P = 0.443) and oxygen extraction (P = 0.582). MRI derived measurements of uteroplacental and fetal VnormalO2 between humans and sheep were similar and in keeping with prior data obtained using invasive techniques. Taken together, these data confirm the reliability of our approach, which offers a novel clinical ‘placental function test’.