Transfontanellar Contrast–Enhanced Ultrasound for Monitoring Brain Perfusion During Neonatal Heart Surgery

hile current mortality rates for neonatal heart surgery are low, 1 there is significant concern about the effects of cardiopulmonary bypass (CPB) on the neonatal brain and later neurodevelopmental impairments.2 To date, no good techniques are available to study the effects of neonatal heart surgery on brain perfusion.The aim of this study is to investigate the potential of transfontanellar contrastenhanced ultrasound (T-CEUS) for quantitative assessment of cerebral blood flow in different phases of neonatal cardiac surgery with and without CPB.In a monocentric, explorative feasibility study n=5 patients with coarctation of the aorta (CoA) and n=7 patients with transposition of great arteries (TGA) were included (URL: http://www.clinicaltrials.gov.Unique identifier: NCT03215628) from September 18, 2017, to March 14, 2019.The study was approved by the local ethics committee (20_17B).Informed consent for the study and the off-label use of the ultrasound contrast agent were obtained from all legal guardians.The data that support the findings of this study are available from the corresponding author on reasonable request.For the CoA group, 3 different time points were selected for T-CEUS imaging: before, during (placement of aortic clamps), and after surgery.For the TGA group, 5 different time points were recorded: before, during high flow of the CPB at 37°C, high flow at 28°C, low flow at 28°C, and after surgery.All patients were hemodynamically stable and without the need of catecholamine therapy before surgery.In total, n=50 measurements (n=15 for CoA and n=35 TGA) were performed directly after reaching the respective stage of surgery.For imaging, a mobile high-end ultrasound system (Mindray, Zonare ZS 3, Zonare Medical System Inc, Mountain View, CA; Software Version 7.5) equipped with a curved array (C9-3/3) was used.The probe was directly positioned at the great fontanelle and a middle coronal imaging plane was kept constant during acquisition.The ultrasound contrast agent (SonoVue, Bracco, Milan, Italy, mean diameter: 2.5 µm) 3 was injected intravenously followed by a flush of 2 mL NaCl 0.9%.4 Injections were only performed after complete visible clearance of circulating microbubbles at a mean interval of 18.9 minutes between the different surgical stages.In the TGA group, the ultrasound contrast agent dose was adjusted with a compensation weight of 1 kg to the total body weight because of the priming volume of 148 mL in the CPB.In a secondary software-based analysis, the regions of interests were delineated by 2 independent blinded investigators using VueBox (Version 7.1, Bracco Suisse SA, Plan-lesouates, Switzerland).By this, 11 dynamic flow parameters (eg, rise time [RT] and time-to-peak as measures for the time required for a contrast bolus to accumulate to a maximum in a specific tissue region) were generated for subsequent analyses.Differences between groups were tested with repeated measures 1-way ANOVA and Dunnett multiple comparisons test.