Flow patterns in the ductus arteriosus during open fetal myelomeningocele repair

Fetal cardiovascular changes during open and fetoscopic in-utero spina bifida closure

OBJECTIVE

Fetoscopic closure of spina bifida using heated and humidified carbon dioxide gas (hhCO2) has been associated with lower maternal morbidity compared with open closure. Fetal cardiovascular changes during these surgical interventions are poorly defined. Our objective was to compare fetal bradycardia (defined as fetal heart rate (FHR) < 110 bpm for 10 min) and changes in umbilical artery (UA) Doppler parameters during open vs fetoscopic closure.

METHODS

This was a prospective cohort study of 22 open and 46 fetoscopic consecutive in-utero closures conducted between 2019 and 2023. Both cohorts had similar preoperative counseling and clinical management. FHR and UA Doppler velocimetry were obtained systematically during preoperative assessment, every 5 min during the intraoperative period, and during the postoperative assessment. FHR, UA pulsatility index (PI) and UA end-diastolic flow (EDF) were segmented into hourly periods during surgery, and the lowest values were averaged for analysis. Umbilical vein maximum velocity was measured in the fetoscopic cohort. At each timepoint at which FHR was recorded, maternal heart rate and systolic and diastolic blood pressure were measured.

RESULTS

Fetal bradycardia occurred in 4/22 (18.2%) cases of open closure and 21/46 (45.7%) cases of fetoscopic closure (P = 0.03). FHR decreased gradually in both cohorts after administration of general anesthesia and decreased further during surgery. FHR was significantly lower during hour 2 of surgery in the fetoscopic-repair cohort compared with the open-repair cohort. The change in FHR from baseline in the final stage of fetal surgery was significantly more pronounced in the fetoscopic-repair cohort compared with the open-repair cohort (mean, -32.4 (95% CI, -35.7 to -29.1) bpm vs -23.5 (95% CI, -28.1 to -18.8) bpm; P = 0.002). Abnormal UA-EDF (defined as absent or reversed EDF) occurred in 3/22 (13.6%) cases in the open-repair cohort and 23/46 (50.0%) cases in the fetoscopic-repair cohort (P = 0.004). There were no differences in UA-EDF or UA-PI between closure techniques at the individual stages of assessment.

CONCLUSIONS

We observed a decrease in FHR and abnormalities in UA Doppler parameters during both open and fetoscopic spina bifida closure. Fetal bradycardia was more prominent during fetoscopic closure following hhCO2 insufflation, but FHR recovered after cessation of hhCO2. Changes in FHR and UA Doppler parameters during in-utero spina bifida closure were transient, no cases required emergency delivery and no fetoscopic closure was converted to open closure. These observations should inform algorithms for the perioperative management of fetal bradycardia associated with in-utero spina bifida closure. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Continuous Fetal Cardiac Monitoring during Fetoscopic Myelomeningocele Repair and Relationship to Spectral Doppler Changes

INTRODUCTION

No evidence-based protocols exist for fetal cardiac monitoring during fetoscopic myelomeningocele (fMMC) repair and intraprocedural spectral Doppler data are limited. We determined the feasibility of continuous fetal echocardiography during fMMC repair and correlated Doppler changes with qualitative fetal cardiac function during each phase of fMMC repair.

METHODS

Patients undergoing fMMC repair had continuous fetal echocardiography interpreted in real-time by pediatric cardiology. Fetal data included fetal heart rate (FHR), qualitative cardiac function, mitral and tricuspid valve inflow waveforms, and umbilical artery (UA), umbilical vein (UV), ductus arteriosus (DA), and ductus venosus (DV) Dopplers.

RESULTS

UA abnormalities were noted in 14/25 patients, UV abnormalities were observed in 2 patients, and DV and DA abnormalities were each noted in 4 patients. Qualitative cardiac function was normal for all patients with the exception of one with isolated left ventricular dysfunction during myofascial flap creation, concurrent with an abnormal UA flow pattern. All abnormalities resolved by the first postoperative day.

CONCLUSIONS

Continuous fetal echocardiography was feasible during all fMMC repairs. Spectral Doppler changes in the UA were common during fMMC procedures but qualitative cardiac dysfunction was rare. Abnormalities in the UV, DV, and DA Dopplers, FHR, and cardiac function were less common findings.

Anesthesia for fetal operative procedures: A systematic review

Objective

The anesthetic management of fetal operative procedures (FOP) is a highly debated topic. Literature on fetal pain perception and response to external stimuli is rapidly expanding. Nonetheless, there is no consensus on the fetal consciousness nor on the instruments to measure pain levels. As a result, no guidelines or clinical recommendations on anesthesia modality during FOP are available. This systematic literature review aimed to collect the available knowledge on the most common fetal interventions, and summarize the reported outcomes for each anesthetic approach. Additional aim was to provide an overall evaluation of the most commonly used anesthetic agents.

Methods

Two systematic literature searches were performed in Embase, Medline, Web of Science Core Collection and Cochrane Central Register of Controlled Trials up to December 2021. To best cover the available evidence, one literature search was mostly focused on fetal surgical procedures; while anesthesia during FOP was the main target for the second search. The following fetal procedures were included: fetal transfusion, laser ablation of placental anastomosis, twin-reversed arterial perfusion treatment, fetoscopic endoluminal tracheal occlusion, thoraco-amniotic shunt, vesico-amniotic shunt, myelomeningocele repair, resection of sacrococcygeal teratoma, ligation of amniotic bands, balloon valvuloplasty/septoplasty, ex-utero intrapartum treatment, and ovarian cyst resection/aspiration. Yielded articles were screened against the same inclusion criteria. Studies reporting anesthesia details and procedures’ outcomes were considered. Descriptive statistical analysis was performed and findings were reported in a narrative manner.

Results

The literature searches yielded 1,679 articles, with 429 being selected for full-text evaluation. A total of 168 articles were included. Overall, no significant differences were found among procedures performed under maternal anesthesia or maternal-fetal anesthesia. Procedures requiring invasive fetal manipulation resulted to be more effective when performed under maternal anesthesia only. Based on the available data, a wide range of anesthetic agents are currently deployed and no consistency has been found neither between centers nor procedures.

Conclusions

This systematic review shows great variance in the anesthetic management during FOP. Further studies, systematically reporting intraoperative fetal monitoring and fetal hormonal responses to external stimuli, are necessary to identify the best anesthetic approach. Additional investigations on pain pathways and fetal pain perception are advisable.

Error traps in anesthesia for fetal interventions

A wide range of fetal interventions are being performed worldwide to save the fetus's life, prevent permanent fetal organ damage, and allow a successful transition to extrauterine life. However, these are invasive procedures and can be associated with serious complications. This article focuses on promoting a culture of safety by highlighting five common error traps while anesthetizing patients for fetal interventions. They include failure to preserve uteroplacental perfusion and gas exchange, failure to achieve adequate uterine relaxation prior to hysterotomy, failure to monitor the fetus and prepare for fetal/neonatal resuscitation, failure to prepare for maternal hemorrhage, and failure to promptly treat uterine atony. Practical tips for avoiding these serious complications will also be discussed.

Prenatal Repair of Spina Bifida: A 2-Center Experience with Open Intrauterine Neurosurgery in Chile

OBJECTIVE

To report the experience with prenatal repair of open spina bifida (OSB) from 2 centers in Chile.

METHODS

Women with a second-trimester fetus with OSB were offered intrauterine neurosurgical repair following the protocol from the Management of Myelomeningocele Study (MOMS) trial. Pediatric follow-up with infants reaching 12 and 30 months of life was also reviewed.

RESULTS

Fifty-eight fetuses with OSB underwent intrauterine repair at an average (±SD) gestational age of 24.8 ± 0.9 weeks. There were 3 (5.1%) intrauterine deaths. The average gestational age at delivery of the remaining 55 cases was 33.3 ± 3.6 weeks, and the average birth weight was 2,172 ± 751 g. Delivery before 30 weeks occurred in 11 cases (20.0%). Two (3.6%) neonatal deaths (<28 days) occurred. At 12 months, a ventriculoperitoneal shunt or an endoscopic third ventriculostomy was required in 25% of the cases. At 30 months, 72.4% of the infants were able to walk.

DISCUSSION

Prenatal neurosurgical repair of OSB is a complex and challenging intervention. Major complications include perinatal death and severe prematurity. No major maternal complications occurred in our series. A reduction in the need for cerebrospinal fluid diversion and an improved ability to walk seem to be the greatest long-term advantages of this procedure.

New Trends in Fetal Anesthesia

Fetal anesthesia teams must understand the pathophysiology and rationale for the treatment of each disease process. Treatment can range from minimally invasive procedures to maternal laparotomy, hysterotomy, and major fetal surgery. Timing may be in early, mid-, or late gestation. Techniques continue to be refined, and the anesthetic plans must evolve to meet the needs of the procedures. Anesthetic plans range from moderate sedation to general anesthesia that includes monitoring of 2 patients simultaneously, fluid restriction, invasive blood pressure monitoring, vasopressor administration, and advanced medication choices to optimize fetal cardiac function.

The Use of Indomethacin with Complete Amniotic Fluid Replacement and Classic Hysterotomy for the Reduction of Perinatal Complications of Intrauterine Myelomeningocele Repair

OBJECTIVE

This study presented outcomes of classical hysterotomy with modified antiprostaglandin therapy for intrauterine repair of foetal myelomeningocele (fMMC) performed in a single perinatal centre.

STUDY DESIGN

Forty-nine pregnant women diagnosed with fMMC underwent classic hysterotomy with anti-prostaglandin management, complete amniotic fluid replacement and high dose indomethacin application.

RESULTS

The average gestational age (GA) at delivery was 34.4 ± 3.4 weeks, with no births before 30 weeks GA. There were 2 foetal deaths. Complete reversal of hindbrain herniation (HH), assessed in magnetic resonance imaging at 30-31 weeks GA was found in 72% of foetuses (mostly with HH grade I prior to fMMC repair). Our protocol resulted in rare use of magnesium sulphate (6%), low incidence of chorioamniotic membrane separation - chorioamniotic membrane separation (6%), preterm premature rupture of membranes - preterm premature rupture of membranes (pPROM; 15%) and preterm labour - preterm labour (PTL; 17%). The postoperative wound continuity of the uterus was usually stable (in 72% of patients), with low frequency of scar thinning (23%).

CONCLUSION

Our protocol results in rare use of tocolytics, and the low occurrences of CMS, pPROM and PTL in relation to other study cohorts: Management of Myelomeningocele Study, Children's Hospital of Philadelphia, and Vanderbilt University Medical Centre.

Doppler changes in umbilical artery and ductus venosus during fetoscopic prenatal surgical repair of myelomeningocele

OBJECTIVE

Cardiac dysfunction has been described in 60% of fetuses undergoing open myelomeningocele (MMC) repair. Routine Doppler evaluation of the umbilical artery (UA) and ductus venosus (DV) is challenging during fetal surgery. The aim of this study was to describe Doppler changes in the UA and DV in a cohort of fetuses during fetoscopic MMC repair.

METHODS

This was a retrospective study of fetuses that underwent fetoscopic repair of MMC at a single institution between 2014 and 2017. Ultrasound images taken intraoperatively were analyzed to describe the changes in Doppler parameters of the UA and DV during fetoscopic MMC repair. The timing of Doppler changes was matched with the phase of surgery to determine whether a pattern to their appearance could be ascertained.

RESULTS

Of the thirty-five cases of fetoscopic MMC repair performed during the study period, Doppler data were available for 15. Of these, UA Doppler data were obtained in 12 cases, and DV Doppler data were obtained in 13 cases. Of the 12 cases for which there were UA data, nine (75%) showed transient absence of end-diastolic flow (EDF), with five (41.7%) of them progressing to reversal of EDF. Of the 13 cases for which there were DV data, nine had elevated pulsatility index; however, none of them had absent or reversed blood flow during atrial contraction. Of the nine cases with absent EDF in the UA, this abnormality first appeared during fetoscopic repair in five (55.6%), after uterus exteriorization but before CO₂ insufflation in two (22.2%), after uterus replacement but before skin closure in one (11.1%) and after CO₂ insufflation but before the start of the MMC repair in one (11.1%). Doppler abnormalities in four fetuses with reversed EDF and in three with absent EDF resolved during surgery. Follow-up examination 1 day after surgery demonstrated resolution of UA and DV Doppler abnormalities in all fetuses.

CONCLUSION

Transient Doppler abnormalities of the UA, without significant changes in the DV, can be seen during fetoscopic MMC repair. The clinical significance of these Doppler findings remains unclear due to their transient and intermittent nature. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Tocolysis for open prenatal repair of myelomeningocele: systematic review

Objectives: To summarize current evidence on the use of tocolytic medications perioperatively for open prenatal repair of fetal myelomeningocele including tocolytic agent options, regimens, efficiency, and potential risks.Methods: A search of Medline, Embase, and SCOPUS databases was conducted from inception to March 2017. Studies that described their tocolytic protocol, gestational age at delivery, perinatal outcomes were included. Studies that did not exclusively assessed fetal myelomeningocele or did not adequately endorse obstetric and neonatal outcomes were excluded. Neither sample size nor language was a basis for exclusion.Results: Out of 570 studies retrieved on initial search, 462 were excluded for irrelevance. Of the 61 remaining titles, 17 were animal studies, 17 were reviews, 12 studied a spectrum of anomalies, three specified fetoscopy, four did not report neonatal outcomes, and one article was retracted. Two studies were added to the pool when the literature search was updated. Nine articles were eventually included; three case reports, six cohort studies with a total of 205 cases. Fetuses were managed at gestational ages between 19 and 30 weeks. Although tocolytic regimens were variable, indomethacin was commonly utilized as a preoperative tocolytic. Magnesium sulfate was usually initiated intraoperatively and was resumed postoperatively for a variable duration (18-48 hours) with or without subcutaneous terbutaline. Gestational age at delivery ranged from 30-37 weeks with an average of 33-35 weeks. Pulmonary edema was reported in two studies to be 2.2-5.5%. Perinatal outcomes were overall favorable.Conclusion: Preoperative indomethacin and postoperative course of magnesium sulfate seem to be a favorable tocolytic option in women with open prenatal myelomeningocele repair. Risks are generally minimal. However, adequate information on the duration of postoperative tocolysis seems to be inadequate.

Variations in ductus arteriosus Doppler parameters in different sonographic views during the second half of gestation

The aim of the present study was to compare the Doppler parameters of the fetal ductus arteriosus (DA) measured in the traditional longitudinal ductal arch (LDA) view and the newly introduced three vessels and trachea (3VT) plane of the fetal upper mediastinum. The peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged maximum velocity (TAMXV) and velocity-time integral (VTI) measurements were taken for 52 fetuses with normal growth (including 29 females). The pulsatility index (PI) and resistance index (RI) were calculated. All parameters for each fetus were measured three times by the same sonographer in the LDA and the 3VT view, and the averages were taken to obtain the final value. Differences in the above values obtained from the LDA and 3VT views were analyzed and the correlation between the differences of all indices and the gestational age (GA) was evaluated using Pearson's linear coefficient of correlation. All of the values were characterized as normally distributed continuous variables by homogeneity of variance analysis. Slight increases in the PSV, EDV, TAMXV and VTI determined in the LDA view were identified compared with those in the 3VT view (P<0.05). Furthermore, these increases were identified to be independent of the GA (P>0.05). However, no significant differences in the impedance indices PI and RI were observed between the two sonographic planes (P>0.05). In conclusion, the LDA view provides a better chance than the 3VT view to obtain higher values of velocity parameters (PSV, EDV, TMAXV and VTI) within the fetal DA, and the differences are independent of the GA. However, no significant variations in the impedance indices PI and RI were observed between these two sonographic planes.

Fetal modified left myocardial performance index monitoring during open surgery for myelomeningocele repair

OBJECTIVE

Fetal hemodynamic changes have already been described during open myelomeningocele repair. This study aimed to access fetal myocardial performance index (MPI) during this high-complexity surgery.

METHODS

Open myelomeningocele repair was performed in 37 fetuses between the 24th and 27th week of gestation. MPI was calculated at specific periods: pre-anesthesia, postanesthesia, neurosurgery (early skin manipulation, spinal cord releasing, and sintesis), and end of surgery. Mean ± standard deviation (SD) of MPI and its related times-isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), and ejection time (ET)-was determined for each period. Analysis of variance (ANOVA) with repeated measures was used to assess differences among these periods. Tukey multiple comparison times test compared global surgery stages.

RESULTS

The mean of MPI in the specific time points was 0.32, 0.32, 0.34, 0.48, 0.36, and 0.32, respectively (P < .001). In the two-tailed comparison times, neurosurgery stage presents MPI highest levels, especially on stage 3b (early skin manipulation and spinal cord releasing) related to ICT and IRT rising and ET decreased levels.

CONCLUSION

Fetal global cardiac function is altered during the open myelomeningocele repair. The neurosurgery stage represents the critical phase of the procedure.

Anesthesia for fetal surgery

Fetal therapy is an exciting and growing field of medicine. Advances in prenatal imaging and continued innovations in surgical and anesthetic techniques have resulted in a wide range of fetal interventions including minimally invasive, open mid-gestation, and ex-utero intrapartum treatment procedures. The potential for maternal morbidity is significant and must be carefully weighed against claimed benefits to the fetus. Appropriate patient selection is critical, and a multidisciplinary team-based approach is strongly recommended. The anesthetic management should focus on maintaining uteroplacental circulation, achieving profound uterine relaxation, optimizing surgical conditions, monitoring fetal hemodynamics, and minimizing maternal and fetal risk.

Fetal Heart Rate Monitoring during Intrauterine Open Surgery for Myelomeningocele Repair

Objective: The aim of this study was to assess fetal hemodynamics during intrauterine open surgery for myelomeningocele (MMC) repair by describing fetal heart rate (FHR) monitoring in detail related to each part of the procedure. Methods: A study was performed with 57 fetuses submitted to intrauterine MMC repair between the 24th and 27th week of gestation. Evaluations of FHR were made in specific periods: before anesthesia, after anesthesia, at the beginning of laparotomy, during uterus abdominal withdrawal, hysterotomy, neurosurgery (before incision, during early skin manipulation, spinal cord releasing, and at the end of neurosurgery), abdominal cavity reintroduction, and abdominal closure, and at the end of surgery. Means ± standard deviations of FHR were established for each period, and analysis of variance with repeated measures was used to assess differences between these periods. The mean differences were assessed with 95% confidence intervals and were analyzed by Tukey's multiple comparison test. Results: The mean FHR during the specific periods mentioned above was 140.2, 140, 139.2, 138.8, 135.1, 133.9, 123.1, 134.0, 134.5, 137.9, and 139.9 bpm, respectively (p < 0.0001). Comparing the different periods, the highest frequencies were observed in the initial and final moments. The neurosurgery stage presents lower frequencies, especially during the release of the spinal cord. Conclusion: FHR monitoring revealed interesting findings in terms of physiological fetal changes during MMC repair, especially during neurosurgery, which was the most critical period.