Neurodevelopmental outcomes after regional cerebral perfusion with neuromonitoring for neonatal aortic arch reconstruction

Neurological injury in pediatric heart disease: A review of developmental and acquired risk factors and management considerations

Medical and surgical advancements have improved survival in children with acquired and congenital heart disease (CHD), but the burden of neurological morbidity is high. Brain disorders associated with CHD include white matter injury, stroke, seizure, and neurodevelopmental delays. While genetics and disease-specific factors play a substantial role in early brain injury, therapeutic management of the heart disease intensifies the risk. There is a growing interest in understanding how to reduce brain injury and improve neurodevelopmental outcomes in cardiac diseases. Pediatric neurologists serve a vital role in care teams managing these complex patients, providing interpretation of neuromonitoring and imaging, managing neurologic emergencies, assisting with neuro prognostication, and identifying future research aims.

Original Article--Risk Factors for Neurological Complications and Short-term Outcomes After Pediatric Heart Surgery: A Retrospective Analysis

Objective

To assess the risk factors associated with neurological complications and poor short-term outcomes following pediatric heart surgery.

Methodology

A cross-sectional study was conducted in a cardiac intensive care unit between June 2019 and June 2022. The data of all children less than 15 years old who underwent open-heart surgery and had CT brain were extracted from hospital records. The primary outcome was the incidence of CNS insult, and secondary outcomes included death after surgery, length of stay in ICU and hospital. Data analysis was performed using SPSS version 23, and a p-value less than or equal to 0.05 was considered statistically significant.

Results

Total 1850 surgeries were performed in the specified period of time. The study included 208 children who had CT Brain, with a median age of 5 months. 2.81 % children had neurological complications, with 25 % of patients who had CT brain. The most common neurological complication was seizure (7.2 %). There were no significant differences observed between CNS insult and age, gender, syndrome, or prematurity (p > 0.05), except for a significant association between previous CNS insult and CNS insult after surgery (p = 0.001). Children with CNS insult had significantly higher ICU and hospital length of stay, mortality after surgery, and mortality within 2 weeks of surgery (p ≤ 0.05).

Conclusion

Seizure was most common neurological manifestation after cardiac surgeries in children. CNS insult after surgery was associated with worse outcomes, including longer hospital stays and increased mortality.

Effects of circulatory arrest and cardiopulmonary bypass on cerebral autoregulation in neonatal swine

BACKGROUND

Cerebral autoregulation mechanisms help maintain adequate cerebral blood flow (CBF) despite changes in cerebral perfusion pressure. Impairment of cerebral autoregulation, during and after cardiopulmonary bypass (CPB), may increase risk of neurologic injury in neonates undergoing surgery. In this study, alterations of cerebral autoregulation were assessed in a neonatal swine model probing four perfusion strategies.

METHODS

Neonatal swine (n = 25) were randomized to continuous deep hypothermic cardiopulmonary bypass (DH-CPB, n = 7), deep hypothermic circulatory arrest (DHCA, n = 7), selective cerebral perfusion (SCP, n = 7) at deep hypothermia, or normothermic cardiopulmonary bypass (control, n = 4). The correlation coefficient (LDx) between laser Doppler measurements of CBF and mean arterial blood pressure was computed at initiation and conclusion of CPB. Alterations in cerebral autoregulation were assessed by the change between initial and final LDx measurements.

RESULTS

Cerebral autoregulation became more impaired (LDx increased) in piglets that underwent DH-CPB (initial LDx: median 0.15, IQR [0.03, 0.26]; final: 0.45, [0.27, 0.74]; p = 0.02). LDx was not altered in those undergoing DHCA (p > 0.99) or SCP (p = 0.13). These differences were not explained by other risk factors.

CONCLUSIONS

In a validated swine model of cardiac surgery, DH-CPB had a significant effect on cerebral autoregulation, whereas DHCA and SCP did not.

IMPACT

Approximately half of the patients who survive neonatal heart surgery with cardiopulmonary bypass (CPB) experience neurodevelopmental delays. This preclinical investigation takes steps to elucidate and isolate potential perioperative risk factors of neurologic injury, such as impairment of cerebral autoregulation, associated with cardiac surgical procedures involving CPB. We demonstrate a method to characterize cerebral autoregulation during CPB pump flow changes in a neonatal swine model of cardiac surgery. Cerebral autoregulation was not altered in piglets that underwent deep hypothermic circulatory arrest (DHCA) or selective cerebral perfusion (SCP), but it was altered in piglets that underwent deep hypothermic CBP.

Near-Infrared Spectroscopy Assessment of Tissue Oxygenation During Selective Cerebral Perfusion for Neonatal Aortic Arch Reconstruction

Objective: Optimal selective cerebral perfusion (SCP) management for neonatal aortic arch surgery has not been extensively studied. We induced mild hypothermia during SCP and used the tissue oxygenation monitor to ensure adequate perfusion during the cardiopulmonary bypass (CPB). Methods: Eight cases were recruited from September 2018 to April 2020. SCP was maintained at 30°C, and CPB was adjusted to achieve a mean right radial artery pressure of 30 mmHg. The near-infrared tissue saturation (NIRS) monitor was applied to assess the right and left brain, flank, and lower extremity during the surgery. Results: During surgery, the mean age was 4.75 days, the mean body weight was 2.92 kg, the CPB duration was 86.5 ±18.7 min, the aortic cross-clamp time was 46.1 ± 12.7 min, and the SCP duration was 14.6±3.4 min. The brain NIRS before, during, and after SCP was 64.2, 67.2, and 71.5 on the left side and 67.9, 66.2, and 70.1 on the right side (p = NS), respectively. However, renal and lower extremity tissue oxygenation, respectively decreased from 61.6 and 62.4 before SCP to 37.7 and 39.9 after SCP (p < 0.05) and then increased to 70.1 and 90.4 after full body flow resumed. No stroke was reported postoperatively. Conclusion: SCP under mild hypothermia can aid in efficient maintenance of brain perfusion during neonatal arch reconstruction. The clinical outcome of this strategy was favorable for up to 20 min, but the safety duration of lower body ischemia warrants further analysis.

The Relationships of Cerebral and Somatic Oxygen Saturation with Physiological Parameters in Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Analysis Using the Random-Effects Model

Recently, tissue oxygenation in pediatric heart surgery is measured by using near-infrared spectroscopy. Monitoring of cerebral oxygen saturation (ScO₂) is most common but that of somatic tissue oxygen saturation (SrO₂) is also gradually becoming widespread. However, the value of their monitoring is not well established. One of the reasons for this may be that the physiological factors affecting ScO₂ and SrO₂ have not been sufficiently clarified. Accordingly, we prospectively observed the changes in ScO₂ and SrO₂ simultaneously throughout cardiac surgery with cardiopulmonary bypass (CPB) in children weighing under 10 kg and evaluated their relationships with physiological parameters by using the random-effects model. ScO₂ and SrO₂ were measured with an INVOS 5100C (Somanetics, Troy, MI, USA). The random-effects analysis was applied for ScO₂ and SrO₂, as dependent variables, and seven physiological parameters (mean blood pressure, central venous pressure, rectal temperature, SaO₂, hematocrit PaCO₂, and pH) were entered as independent covariates. The analysis was performed during the pre-CPB, CPB, and post-CPB periods. Next, the same analysis was performed by dividing the patients into univentricular and biventricular physiological types. Forty-one children were evaluated. Through the whole surgical period, ScO₂ correlated strongly with mean blood pressure regardless of the physiological type. On the other hand, the contribution of mean blood pressure to SrO₂ was weak and various other parameters were related to SrO₂ changes. Thus, the physiological parameters affecting ScO₂ and SrO₂ were rather different. Accordingly, the significance of monitoring of cerebral and somatic tissue oxygen saturation in pediatric cardiac surgery should be further evaluated.

Developmental outcomes after early surgery for complex congenital heart disease: a systematic review and meta-analysis

AIM

(1) To systematically review the literature on developmental outcomes from infancy to adolescence of children with complex congenital heart disease (CHD) who underwent early surgery; (2) to run a meta-regression analysis on the Bayley Scales of Infant Development, Second Edition Mental Developmental Index and Psychomotor Developmental Index (PDI) of infants up to 24 months and IQs of preschool-aged children to adolescents; (3) to assess associations between perioperative risk factors and outcomes.

METHOD

We searched pertinent literature (January 1990 to January 2019) in PubMed, Embase, CINAHL, and PsycINFO. Selection criteria included infants with complex CHD who had primary surgery within the first 9 weeks of life. Methodological quality, including risk of bias and internal validity, were assessed.

RESULTS

In total, 185 papers met the inclusion criteria; the 100 with high to moderate methodological quality were analysed in detail. Substantial heterogeneity in the group with CHD and in methodology existed. The outcome of infants with single-ventricle CHD was inferior to those with two-ventricle CHD (respectively: average scores for PDI 77 and 88; intelligence scores 92 and 98). Perioperative risk factors were inconsistently associated with developmental outcomes.

INTERPRETATION

The literature on children undergoing surgery in early infancy suggests that infants with a single ventricle are at highest risk of adverse developmental outcomes.

Cerebral regional oxygen saturation variability in neonates following cardiac surgery

BACKGROUND

Reduced cerebral regional oxygen saturation (crSO₂) variability in neonates, as measured by near-infrared spectroscopy, following cardiac surgery with deep hypothermic circulatory arrest (DHCA) is associated with poor neurodevelopmental outcomes. We sought to evaluate the variability of crSO₂ in a cohort of neonates following cardiac surgery with brief or no exposure to DHCA.

METHODS

Variability of averaged 1-min crSO₂ values was calculated for the first 48 h following cardiac surgery in consecutive neonates over a 30-month period. Neonates requiring aortic arch repair underwent antegrade cerebral perfusion with either brief or no exposure to DHCA.

RESULTS

There were 115 neonates included in the study. Reduced crSO₂ variability was observed in neonates with aortic arch obstruction (p = 0.02) and non-survivors (p = 0.02). Post hoc analysis demonstrated that the reduction in crSO₂ variability was not as marked as in previously studied neonates with aortic arch obstruction who received DHCA alone (p < 0.001).

CONCLUSIONS

Neonates with aortic arch obstruction have reduced crSO₂ variability following cardiac surgery. The reduction in crSO₂ variability observed in aortic arch obstruction is likely influenced by a number of factors, including perioperative perfusion technique. The impact of interventions on crSO₂ variability and resultant influence on neurodevelopmental outcomes requires further study.

IMPACT

Neonates with aortic arch obstruction have reduced crSO₂ variability following cardiac surgery, which has been associated with poor neurodevelopmental outcomes, and is likely influenced by a number of factors, including perioperative perfusion technique. The contribution of perioperative perfusion technique to crSO₂ variability following neonatal cardiac surgery is significant. Monitoring of crSO₂ variability may provide insights into the adequacy of cerebral perfusion in neonates following cardiac surgery.

Total circulatory arrest as a support modality in congenital heart surgery: review and current evidence

The use of total circulatory arrest (TCA)/deep hypothermic circulatory arrest (DHCA) as a support modality in congenital heart surgery is a time-tested strategy. However, with technological advances, the widespread use of this technique has decreased. Adjunctive cerebral perfusion with continuous cardiopulmonary bypass (CPB) gradually has become more popular with a view to reduce the complications related to DHCA. In addition, better neuromonitoring and neuroprotective strategies have made DHCA much safer. However, the level of evidence to support the best way to protect the brain during congenital heart surgery is insufficient. This review analyzes the history, physiology, techniques of DHCA, as well as other alternative strategies like selective cerebral perfusion and presents the current available evidence.

Antenatal and Perioperative Mechanisms of Global Neurological Injury in Congenital Heart Disease

Congenital heart defects (CHD) is one of the most common types of birth defects. Thanks to advances in surgical techniques and intensive care, the majority of children with severe forms of CHD survive into adulthood. However, this increase in survival comes with a cost. CHD survivors have neurological functioning at the bottom of the normal range. A large spectrum of central nervous system dysmaturation leads to the deficits seen in critical CHD. The heart develops early during gestation, and CHD has a profound effect on fetal brain development for the remainder of gestation. Term infants with critical CHD are born with an immature brain, which is highly susceptible to hypoxic-ischemic injuries. Perioperative blood flow disturbances due to the CHD and the use of cardiopulmonary bypass or circulatory arrest during surgery cause additional neurological injuries. Innate patient factors, such as genetic syndromes and preterm birth, and postoperative complications play a larger role in neurological injury than perioperative factors. Strategies to reduce the disability burden in critical CHD survivors are urgently needed.

Continuous cerebral and myocardial selective perfusion in neonatal aortic arch surgery

BACKGROUND

To assess the feasibility and early outcome of continuous cerebral and myocardial selective perfusion (CCMSP) during aortic arch surgery in neonates.

METHODS

We performed a single-center retrospective study between 2008 and 2019 on neonates who underwent aortic arch surgery with or without associated heart lesion repair. CCMSP with moderate hypothermia levels (28°C) was achieved using selective brachiocephalic artery and ascending aorta cannulation. Target rates of cerebral and myocardial perfusion were 25 to 35 mL/kg/min and 150 ml/m2/min. Cardiopulmonary bypass (CPB) variables and clinical outcomes were analyzed.

RESULTS

Overall, 69 neonates underwent either isolated aortic arch repair (n = 31) or aortic arch repair with ventricular septal defect (VSD) closure (n = 38). Age and weight medians were 8 [6 to 15] days and 3.4 [2.9-3.5] kg, respectively. Mean CPB and aortic clamping times were 134 ± 47 and 26 ± 5 minutes for isolated aortic arch repair, and 159 ± 47 and 75 ± 30 minutes for aortoplasty accompanied by VSD closure. Mean CCMSP time was 52 ± 21 minutes with cerebral rate of 32.6 ± 10 mL·kg^-1 ·min^-1 . Overall in hospital survival was 98.5% (68/69). Major complications were: postoperative cardiac failure requiring mechanical support followed by stroke (n = 1; 1.44%) and transient renal failure requiring dialysis (n = 2; 2.89%). Neither myocardial nor digestive complication occurred.

CONCLUSION

CCMSP is a safe and reproducible strategy for cerebral, myocardial and visceral protection in neonatal aortic arch repair, with or without VSD closure, resulting in low complication and mortality.

A referral pathway for potentially abnormal neurodevelopment in children with heart disease in the United Kingdom: a Delphi consensus

INTRODUCTION

Children with congenital heart disease have complex medical and neurodevelopmental needs. We aimed to develop a multi-professional consensus-based referral pathway applicable to action the results of the brief developmental assessment (BDA), a validated early recognition tool, that categorises the neurodevelopmental status as green (appropriate for age), amber (equivocal) or red (delayed) in children aged between 4 months and 5 years.

METHODS

A Delphi consensus survey detailing two scenarios-a child categorised as delayed (red) and another as equivocal (amber) on administration of the BDA at the time of discharge from the tertiary centre-was sent to 80 expert professionals from primary, secondary and tertiary care seeking agreement on next steps and referral pathways. An iterative process was proposed with a pre-defined rule of 75% for consensus.

RESULTS

The survey was completed by 77 Delphi panel experts in Round 1, 73 in Round 2 and 70 in Round 3. Consensus was achieved (1) for the child with amber or red BDA, the child should be under the care of a paediatrician with expertise in cardiology (PEC) (or general paediatrician if no PEC) based at their local hospital, (2) for the child with red BDA, the PEC should initiate referral to community services at first assessment, (3) for child with amber BDA, a re-assessment by the health visitor should occur within 1-2 months, with referral to community services and notification to the PEC if on-going concerns.

CONCLUSIONS

The Delphi process enabled a consensus to be reached between health professionals on referral pathways for specialist neurodevelopmental assessment/treatment for children with heart disease, in response to amber or red BDA results. The agreed referral pathway, if implemented, could underpin a national guideline to address and intervene on the neurodevelopmental difficulties in children with heart disease.

Neurologic Injury in Neonates Undergoing Cardiac Surgery

Neurodevelopmental outcomes after neonatal congenital heart surgery are significantly influenced by brain injury detectable by MRI imaging techniques. This brain injury can occur in the prenatal and postnatal periods even before cardiac surgery. Given the significant incidence of new MRI brain injury after cardiac surgery, much work is yet to be done on strategies to detect, prevent, and treat brain injury in the neonatal period in order to optimize longer-term neurodevelopmental outcomes.

Agreement between frontal and occipital regional cerebral oxygen saturation in infants during surgery and general anesthesia an observational study

BACKGROUND

Advances in perioperative pediatric care have resulted in an increased number of procedures requiring anesthesia. During anesthesia and surgery, the patient is subjected to factors that affect the circulatory homeostasis, which can influence oxygenation of the brain. Near-infrared spectroscopy (NIRS) is an easy applicable noninvasive method for monitoring of regional tissue oxygenation (rScO₂%). Alternate placements for NIRS have been investigated; however, no alternative cranial placements have been explored.

AIM

To evaluate the agreement between frontal and occipital recordings of rScO₂% in infants using INVOS^TM during surgery and general anesthesia.

METHOD

A standard frontal monitoring of rScO₂% with NIRS was compared with occipital rScO₂% measurements in fifteen children at an age <1 year, ASA 1-2, undergoing cleft lip and/or palate surgery during general anesthesia with sevoflurane. An agreement analysis was performed according to Bland and Altman.

RESULTS

Mean values of frontal and occipital rScO₂% at baseline were largely similar (70.7 ± 4.77% and 69.40 ± 5.04%, respectively). In the majority of the patients, the frontal and occipital recordings of rScO₂ changed in parallel. There was a moderate positive correlation between frontal and occipital rScO₂% INVOS™ readings (rho[ρ]: 0.513, P < .01). The difference between frontal and occipital rScO₂ ranged from -31 to 28 with a mean difference (bias) of -0.15%. The 95% limit of agreement was -18.04%-17.74%. The error between frontal and occipital rScO₂ recordings was 23%.

CONCLUSION

The agreement between frontal and occipital recordings of brain rScO₂% in infants using INVOS^TM during surgery and general anesthesia was acceptable. In surgical procedures where the frontal region of the head is not available for monitoring, occipital recordings of rScO₂% could be an option for monitoring.

Near-Infrared Spectroscopy in Pediatric Congenital Heart Disease

Near-infrared spectroscopy (NIRS) is widely used to monitor tissue oxygenation in the pediatric cardiac surgical population. Clinicians who use NIRS must understand the underlying measurement principles in order to interpret and use this monitoring modality appropriately. The aims of this narrative review are to provide a brief overview of NIRS technology, discuss the normative and critical values of cerebral and somatic tissue oxygen saturation and the interpretation of these values, present the clinical studies (and their limitations) of NIRS as a perioperative monitoring modality in the pediatric congenital heart disease population, and introduce the emerging and future applications of NIRS.

Neurodevelopmental Delay After the Neonatal Repair of Coarctation and Arch Obstruction

BACKGROUND

Although single ventricle physiology and cyanosis are known risk factors for neurodevelopmental delay (NDD), the impacts of isolated coarctation (Iso CoA) repair or arch reconstruction (AR) are less understood.

METHODS

The Vineland Adaptive Behavior Scales, third edition, prospectively evaluated children without a genetic syndrome. An overall composite score, normalized to age and sex, was generated from individual domain scores. NDD was defined as a composite or domain score at least 1 SD less than the established mean. Iso CoA was repaired using a left thoracotomy, whereas AR was performed using a sternotomy and cardiopulmonary bypass. Children with a structurally normal heart and without previous surgery were used as control patients.

RESULTS

Of 60 children, 50 required neonatal repair (12 for Iso CoA, 38 for AR), and 10 were control patients. From the entire cohort of children who required neonatal coarctation repair (Iso CoA + AR) composite (93.9 ± 15.9 vs 105.0 ± 7.4; P = .004) and all domain scores were significantly lower than control patients. NDD was present in 25 of 50 children after repair and in 0 of 10 control patients (P = .003). Similarly, the prevalence of NDD was significantly greater after Iso CoA repair (58.3% vs 0%; P = .005) and AR (47.3% vs 0%; P = .007) than in the control population, but no significant difference was found between the Iso CoA and AR groups (P = .74).

CONCLUSIONS

In this small cohort, half of the neonates who required either Iso CoA repair or AR exhibit NDD at an intermediate-term follow-up.

Evaluation of Postnatal Sedation in Full-Term Infants

Prolonged sedation in infants leads to a high incidence of physical dependence. We inquired: (1) "How long does it take to develop physical dependence to sedation in previously naïve full-term infants without known history of neurologic impairment?" and (2) "What is the relationship between length of sedation to length of weaning and hospital stay?". The retrospective study included full-term patients over a period of one year that were <1 year of age and received opioids and benzodiazepines >72 hours. Quantification of fentanyl, morphine, and midazolam were compared among three time periods: <5 days, 5-30 days, and >30 days using t-test or one-way analysis of variance. Identified full-term infants were categorized into surgical (14/44) or medical (10/44) groups, while those with neurological involvement (20/44) were excluded. Physical dependence in full-term infants occurred following sedation ≥5 days. Infants with surgical disease received escalating doses of morphine and midazolam when administered >30 days. A positive association between length of sedation and weaning period was found for both respiratory (p < 0.01) and surgical disease (p = 0.012) groups, while length of sedation is related to hospital stay for the respiratory (p < 0.01) but not the surgical disease group (p = 0.1). Future pharmacological directions should lead to standardized sedation protocols and evaluate patient neurocognitive outcomes.

Recent Advances in Congenital Heart Surgery: Alternative Perfusion Strategies for Infant Aortic Arch Repair

PURPOSE OF REVIEW

This paper will discuss current cannulation strategies for infant aortic arch repair and compare them to more traditionally used techniques.

RECENT FINDINGS

Aortic arch reconstruction in infants has traditionally involved deep hypothermic circulatory arrest which results in total body ischemia. This has been associated with an increased risk of morbidity including bleeding, renal dysfunction, and neurologic injury. Advances in perfusion techniques have allowed for preserved perfusion to the brain during arch repair. Current techniques have further evolved that allow for continuous perfusion of the heart and even the lower body during arch reconstruction. With current techniques, aortic arch reconstruction in infants can be performed with continuous perfusion to the brain, heart, and lower body. Further technical refinements will be helpful, and study is necessary to evaluate the benefit of these strategies.

Selective versus standard cerebro-myocardial perfusion in neonates undergoing aortic arch repair: A multi-center study

The results of neonatal aortic arch surgery using cerebro-myocardial perfusion were analyzed. Selective cerebral and myocardial perfusion, using two separate pump rotors, was compared with standard perfusion, using a single pump rotor with an arterial line Y-connector. Between May 2008 and May 2016, 69 consecutive neonates underwent arch repair using either selective cerebro-myocardial perfusion (Group A, n = 34) or standard perfusion (Group B, n = 35). The groups were similar for age, weight, BSA, prevalence of one-stage or staged repair, and single ventricle palliation; male gender was more frequent in Group A. The duration of the cerebro-myocardial perfusion was comparable (27 ± 8 vs. 28 ± 7 min, P = 0.9), with higher flows in Group A (57 ± 27 vs. 39 ± 19 mL/kg/min, P = 0.01). Although cardioplegic arrest was more common in Group B (13/34 vs. 23/35, P = 0.03), the duration of myocardial ischemia was longer in Group A (64 ± 41 vs. 44 ± 14 min, P = 0.04). There was 1 hospital death in each group, with no permanent neurological injury in either group. Cardiac morbidity (1/34 vs. 7/35, P = 0.02) was more common in Group B, while extracardiac morbidity was similar in both the groups. During follow-up (3.2 ± 2.4 years), 5 late deaths occurred with a comparable 5-year survival rate (75 ± 17% vs. 88 ± 6%, P = 0.7) and freedom from arch reintervention (86 ± 6% vs. 84 ± 7%, P = 0.6). Risk of cardiac morbidity was greater with standard cerebro-myocardial perfusion (OR = 5.2, CI 3.3-6.8, P = 0.001) and with perfusion flows less than 50 mL/kg/min (OR 3.7, CI 1.87-5.95, P = 0.04). Cerebro-myocardial perfusion is a safe and effective strategy to protect the brain and heart in neonates undergoing arch repair. Selective techniques using higher perfusion flows may further attenuate cardiac morbidity.

Markers of peripheral perfusion during high-flow regional cerebral perfusion for aortic arch repair

OBJECTIVES

High-flow regional cerebral perfusion (HFRCP) provides cerebral and somatic oxygen delivery through collateral vessels during aortic arch repair in small children; however, optimal flow conditions during HFRCP have not been established. We sought to identify markers of peripheral perfusion during HFRCP.

METHODS

Between 2009 and 2016, in total 20 consecutive pediatric patients undergoing aortic arch repair with HFRCP were enrolled in this prospective, observational study. Median age was 20 days (range, 6-116 days); median body weight was 2.77 kg (range, 1.8-4.98 kg). Oxygen delivery ratio (Do₂R) was calculated as the oxygen delivery during HFRCP divided by the oxygen delivery before HFRCP. Regional oxygen saturations on the forehead and on the thigh (rSo₂T) were monitored during HFRCP, and postoperative creatinine kinase and lactate concentrations were measured as postoperative outcomes. Multivariate analyses were performed to clarify the effectiveness of Do₂R and rSo₂T as markers of peripheral perfusion during HFRCP.

RESULTS

No deaths or neurologic impairments occurred. Multivariate analysis showed that the lowest rSo₂T (P = .005) and cardiopulmonary bypass time (P = .012) predicted postoperative creatinine kinase concentration. Do₂R was the only factor to predict postoperative lactate concentration (P < .001). Receiver operating characteristic analysis showed that Do₂R less than 0.66 predicted risk of high postoperative lactate concentration (>5.0 mmol/L), with area under the curve of 0.95.

CONCLUSIONS

For aortic arch repair in small children, rSo₂T and Do₂R during HFRCP are useful markers for predicting peripheral perfusion. Maintaining higher Do₂R during HFRCP minimizes postoperative increases in lactate and creatinine kinase concentrations.

Selective Cerebro-Myocardial Perfusion in Complex Neonatal Aortic Arch Pathology: Midterm Results

Aortic arch repair in newborns and infants has traditionally been accomplished using a period of deep hypothermic circulatory arrest. To reduce neurologic and cardiac dysfunction related to circulatory arrest and myocardial ischemia during complex aortic arch surgery, an alternative and novel strategy for cerebro-myocardial protection was recently developed, where regional low-flow perfusion is combined with controlled and independent coronary perfusion. The aim of the present retrospective study was to assess short-term and mid-term results of selective and independent cerebro-myocardial perfusion in neonatal aortic arch surgery. From April 2008 to August 2015, 28 consecutive neonates underwent aortic arch surgery under cerebro-myocardial perfusion. There were 17 male and 11 female, with median age of 15 days (3-30 days) and median body weight of 3 kg (1.6-4.2 kg), 9 (32%) of whom with low body weight (<2.5 kg). The spectrum of pathologies treated was heterogeneous and included 13 neonates having single-stage biventricular repair (46%), 7 staged biventricular repair (25%), and 8 single-ventricle repair (29%). All operations were performed under moderate hypothermia and with a "beating heart and brain." Average cardiopulmonary bypass time was 131 ± 64 min (42-310 min). A period of cardiac arrest to complete intra-cardiac repair was required in nine patients (32%), and circulatory arrest in 1 to repair total anomalous pulmonary venous connection. Average time of splanchnic ischemia during cerebro-myocardial perfusion was 30 ± 11 min (15-69 min). Renal dysfunction, requiring a period of peritoneal dialysis was observed in 10 (36%) patients, while liver dysfunction was noted only in 3 (11%). There were three (11%) early and two late deaths during a median follow-up of 2.9 years (range 6 months-7.7 years), with an actuarial survival of 82% at 7 years. At latest follow-up, no patient showed signs of cardiac or neurologic dysfunction. The present experience shows that a strategy of selective and independent cerebro-myocardial perfusion is safe, versatile, and feasible in high-risk neonates with complex congenital arch pathology. Encouraging outcomes were noted in terms of cardiac and neurological function, with limited end-organ morbidity.

Is Decellularized Porcine Small Intestine Sub-mucosa Patch Suitable for Aortic Arch Repair?

Introduction: We reviewed our experience with decellularized porcine small intestine sub-mucosa (DPSIS) patch, recently introduced for congenital heart defects. Materials and Methods: Between 10/2011 and 04/2016 a DPSIS patch was used in 51 patients, median age 1.1 months (5 days to 14.5 years), for aortic arch reconstruction (45/51 = 88.2%) or aortic coarctation repair (6/51 = 11.8%). All medical records were retrospectively reviewed, with primary endpoints interventional procedure (balloon dilatation) or surgery (DPSIS patch replacement) due to patch-related complications. Results: In a median follow-up time of 1.5 ± 1.1 years (0.6-2.3years) in 13/51 patients (25.5%) a re-intervention, percutaneous interventional procedure (5/51 = 9.8%) or re-operation (8/51 = 15.7%) was required because of obstruction in the correspondence of the DPSIS patch used to enlarge the aortic arch/isthmus, with median max velocity flow at Doppler interrogation of 4.0 ± 0.51 m/s. Two patients required surgery after failed interventional cardiology. The mean interval between DPSIS patch implantation and re-intervention (percutaneous procedure or re-operation) was 6 months (1-17 months). While there were 3 hospital deaths (3/51 = 5.9%) not related to the patch implantation, no early or late mortality occurred for the subsequent procedure required for DPSIS patch interventional cardiology or surgery. The median max velocity flow at Doppler interrogation through the aortic arch/isthmus for the patients who did not require interventional procedure or surgery was 1.7 ± 0.57 m/s. Conclusions: High incidence of re-interventions with DPSIS patch for aortic arch and/or coarctation forced us to use alternative materials (homografts and decellularized gluteraldehyde preserved bovine pericardial matrix).

An International, Multicenter, Observational Study of Cerebral Oxygenation during Infant and Neonatal Anesthesia

BACKGROUND

General anesthesia during infancy is associated with neurocognitive abnormalities. Potential mechanisms include anesthetic neurotoxicity, surgical disease, and cerebral hypoxia-ischemia. This study aimed to determine the incidence of low cerebral oxygenation and associated factors during general anesthesia in infants.

METHODS

This multicenter study enrolled 453 infants aged less than 6 months having general anesthesia for 30 min or more. Regional cerebral oxygenation was measured by near-infrared spectroscopy. We defined events (more than 3 min) for low cerebral oxygenation as mild (60 to 69% or 11 to 20% below baseline), moderate (50 to 59% or 21 to 30% below baseline), or severe (less than 50% or more than 30% below baseline); for low mean arterial pressure as mild (36 to 45 mmHg), moderate (26 to 35 mmHg), or severe (less than 25 mmHg); and low pulse oximetry saturation as mild (80 to 89%), moderate (70 to 79%), or severe (less than 70%).

RESULTS

The incidences of mild, moderate, and severe low cerebral oxygenation were 43%, 11%, and 2%, respectively; mild, moderate, and severe low mean arterial pressure were 62%, 36%, and 13%, respectively; and mild, moderate, and severe low arterial saturation were 15%, 4%, and 2%, respectively. Severe low oxygen saturation measured by pulse oximetry was associated with mild and moderate cerebral desaturation; American Society of Anesthesiology Physical Status III or IV versus I was associated with moderate cerebral desaturation. Severe low cerebral saturation events were too infrequent to analyze.

CONCLUSIONS

Mild and moderate low cerebral saturation occurred frequently, whereas severe low cerebral saturation was uncommon. Low mean arterial pressure was common and not well associated with low cerebral saturation. Unrecognized severe desaturation lasting 3 min or longer in infants seems unlikely to explain the subsequent development of neurocognitive abnormalities.

Current Readings on Surgery for the Neonate With Hypoplastic Aortic Arch

Aortic arch hypoplasia is commonly present in neonates born with ductal-dependent coarctation of the aorta. The ideal surgical repair of neonates with proximal arch hypoplasia continues to be debated. Controversy exists about the fate of the hypoplastic proximal aortic arch following surgical repair and whether that will eventually grow to normal size upon relief of the distal obstruction or will persist as a residual lesion that can affect the long-term outlook of those patients. There is new evidence that residual proximal arch hypoplasia and the shape of the reconstructed arch both have an important impact on vascular remodeling and on the subsequent development of hypertension. Those concerns about late outcomes despite what was originally deemed a successful repair in infancy, coupled with improved cardiopulmonary bypass and cerebral perfusion techniques that allow surgeons to address proximal arch hypoplasia with low morbidity, have rekindled the debate on how to address proximal arch hypoplasia, with the aim to offer a neonatal surgery that would last for a lifetime and provide both optimal early recovery and late freedom from hypertension and related complications.

Static cerebrovascular pressure autoregulation remains intact during deep hypothermia

BACKGROUND

Clinical studies measuring cerebral blood flow in infants during deep hypothermia have demonstrated diminished cerebrovascular pressure autoregulation. The coexistence of hypotension in these cohorts confounds the conclusion that deep hypothermia impairs cerebrovascular pressure autoregulation.

AIM

We sought to compare the lower limit of autoregulation and the static rate of autoregulation between normothermic and hypothermic piglets.

METHODS

Twenty anesthetized neonatal piglets (5-7 days old; 10 normothermic and 10 hypothermic to 20°C) had continuous measurements of cortical red cell flux using laser Doppler flowmetry, while hemorrhagic hypotension was induced without cardiopulmonary bypass. Lower limit of autoregulation was determined for each subject using piecewise regression and SRoR was determined above and below each lower limit of autoregulation as (%change cerebrovascular resistance/%change cerebral perfusion pressure).

RESULTS

The estimated difference in lower limit of autoregulation was 1.4 mm Hg (lower in the hypothermic piglets; 95% C.I. -10 to 14 mm Hg; P=0.6). The median lower limit of autoregulation in the normothermic group was 39 mm Hg [IQR 38-51] vs 35 mm Hg [31-50] in the hypothermic group. Intact steady-state pressure autoregulation was defined as static rate of autoregulation >0.5 and was demonstrated in all normothermic subjects (static rate of autoregulation=0.72 [0.65-0.87]) and in 9/10 of the hypothermic subjects (static rate of autoregulation=0.65 [0.52-0.87]). This difference in static rate of autoregulation of 0.06 (95% C.I. -0.3 to 0.1) was not significant (P=0.4).

CONCLUSION

Intact steady-state cerebrovascular pressure autoregulation is demonstrated in a swine model of profound hypothermia. Lower limit of autoregulation and static rate of autoregulation were similar in hypothermic and normothermic subjects.

Neonatal Aortic Arch Reconstruction With Direct Splanchnic Perfusion Avoids Deep Hypothermia

BACKGROUND

Neonatal aortic arch reconstruction, typically performed with deep hypothermia and selective cerebral perfusion, leaves splanchnic organ protection dependent on hypothermia alone. A simplified method of direct in-field descending aortic perfusion during neonatal arch reconstruction permits the avoidance of deep hypothermia. We hypothesize that direct splanchnic perfusion at mild hypothermia provides improved or equivalent safety compared with deep hypothermia and may contribute to postoperative extracardiac organ recovery.

METHODS

Included were 138 biventricular patients aged younger than 90 days undergoing aortic arch reconstruction with cardiopulmonary bypass. Patients were grouped according to perfusion method A (selective cerebral perfusion with deep hyperthermia at 18° to 20°C) or method B (selective cerebral perfusion and splanchnic perfusion at 30° to 32°C). Patient characteristics and perioperative clinical and serologic data were analyzed. Significance was assigned for p of less than 0.05.

RESULTS

Of the 138 survivors, 63 underwent method A and 75 underwent method B. The median age at operation was 8.5 days (range, 6 to 15 days), and median weight was 3.2 kg (range, 2.8 to 3.73 kg), with no significant differences between groups. Cardiopulmonary bypass times were comparable between the two perfusion methods (p = 0.255) as were the ascending aortic cross-clamp times (p = 0.737). The postoperative glomerular filtration rate was significantly different between our groups (p = 0.028 to 0.044), with method B achieving a higher glomerular filtration rate. No significant differences were seen in ventilator time, postoperative length of stay, fractional increase of postoperative serum creatinine over preoperative serum creatinine, and postoperative lactate.

CONCLUSIONS

A simplified method of direct splanchnic perfusion during neonatal aortic arch reconstruction avoids the use of deep hypothermia and provides renal protection at least as effective as deep hypothermia.

Variation in Perfusion Strategies for Neonatal and Infant Aortic Arch Repair: Contemporary Practice in the STS Congenital Heart Surgery Database

BACKGROUND

Regional cerebral perfusion (RCP) is used as an adjunct or alternative to deep hypothermic circulatory arrest (DHCA) for neonates and infants undergoing aortic arch repair. Clinical studies have not demonstrated clear superiority of either strategy, and multicenter data regarding current use of these strategies are lacking. We sought to describe the variability in contemporary practice patterns for use of these techniques.

METHODS

The Society of Thoracic Surgeons Congenital Heart Surgery Database (2010-2013) was queried to identify neonates and infants whose index operation involved aortic arch repair with cardiopulmonary bypass. Perfusion strategy was classified as isolated DHCA, RCP (with less than or equal to ten minutes of DHCA), or mixed (RCP with more than ten minutes of DHCA). Data were analyzed for the entire cohort and stratified by operation subgroups.

RESULTS

Overall, 4,523 patients (105 centers) were identified; median age seven days (interquartile range: 5.0-13.0). The most prevalent perfusion strategy was RCP (43%). Deep hypothermic circulatory arrest and mixed perfusion accounted for 32% and 16% of cases, respectively. In all, 59% of operations involved some period of RCP. Regional cerebral perfusion was the most prevalent perfusion strategy for each operation subgroup. Neither age nor weight was associated with perfusion strategy, but reoperations were less likely to use RCP (31% vs 45%, P < .001). The combined duration of RCP and DHCA in the RCP group was longer than the DHCA time in the DHCA group (45 vs 36 minutes, P < .001).

CONCLUSION

There is considerable variability in practice regarding perfusion strategies for arch repair in neonates and infants. In contemporary practice, RCP is the most prevalent perfusion strategy for these procedures. Use of DHCA is also common. Further investigation is warranted to ascertain possible relative merits of the various perfusion techniques.

Non-invasive Assessment of Cerebral Blood Flow and Oxygen Metabolism in Neonates during Hypothermic Cardiopulmonary Bypass: Feasibility and Clinical Implications

The neonatal brain is extremely vulnerable to injury during periods of hypoxia and/or ischemia. Risk of brain injury is increased during neonatal cardiac surgery, where pre-existing hemodynamic instability and metabolic abnormalities are combined with long periods of low cerebral blood flow and/or circulatory arrest. Our understanding of events associated with cerebral hypoxia-ischemia during cardiopulmonary bypass (CPB) remains limited, largely due to inadequate tools to quantify cerebral oxygen delivery and consumption non-invasively and in real-time. This pilot study aims to evaluate cerebral blood flow (CBF) and oxygen metabolism (CMRO₂) intraoperatively in neonates by combining two novel non-invasive optical techniques: frequency-domain near-infrared spectroscopy (FD-NIRS) and diffuse correlation spectroscopy (DCS). CBF and CMRO₂ were quantified before, during and after deep hypothermic cardiopulmonary bypass (CPB) in nine neonates. Our results show significantly decreased CBF and CMRO₂ during hypothermic CPB. More interestingly, a change of coupling between both variables is observed during deep hypothermic CPB in all subjects. Our results are consistent with previous studies using invasive techniques, supporting the concept of FD-NIRS/DCS as a promising technology to monitor cerebral physiology in neonates providing the potential for individual optimization of surgical management.

Landmark papers in pediatric cardiac anesthesia: documenting the history of the specialty

Pediatric cardiac anesthesia has developed over the past eight decades into a specialty delivering complex clinical care and contributing remarkable scientific progress. The history of this development can be traced through journal articles that mark the strides of the specialty. This article discusses journal articles, chosen by the author, that he considers had a significant impact on the practice of pediatric cardiac anesthesia or are of historical interest.

Near Infrared Spectroscopy as a Hemodynamic Monitor in Critical Illness

OBJECTIVES

The objectives of this review are to discuss the technology and clinical interpretation of near infrared spectroscopy oximetry and its clinical application in patients with congenital heart disease.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

Near infrared spectroscopy provides a continuous noninvasive assessment of tissue oxygenation. Over 20 years ago, near infrared spectroscopy was introduced into clinical practice for monitoring cerebral oxygenation during cardiopulmonary bypass in adults. Since that time, the utilization of near infrared spectroscopy has extended into the realm of pediatric cardiac surgery and is increasingly being used in the cardiac ICU to monitor tissue oxygenation perioperatively.

Goal-directed-perfusion in neonatal aortic arch surgery

Reduction of mortality and morbidity in congenital cardiac surgery has always been and remains a major target for the complete team involved. As operative techniques are more and more standardized and refined, surgical risk and associated complication rates have constantly been reduced to an acceptable level but are both still present. Aortic arch surgery in neonates seems to be of particular interest, because perfusion techniques differ widely among institutions and an ideal form of a so called "total body perfusion (TBP)" is somewhat difficult to achieve. Thus concepts of deep hypothermic circulatory arrest (DHCA), regional cerebral perfusion (RCP/with cardioplegic cardiac arrest or on the perfused beating heart) and TBP exist in parallel and all carry an individual risk for organ damage related to perfusion management, chosen core temperature and time on bypass. Patient safety relies more and more on adequate end organ perfusion on cardiopulmonary bypass, especially sensitive organs like the brain, heart, kidney, liver and the gut, whereby on adequate tissue protection, temperature management and oxygen delivery should be visualized and monitored.

Cognitive Dysfunction in Children with Heart Disease: The Role of Anesthesia and Sedation

As physicians and caregivers of children with congenital heart disease, we are aware of the increasing need for procedures requiring anesthesia. While these procedures may be ideal for medical and cardiac surgical management, the risks and benefits must be assessed carefully. There are well known risks of cardiovascular and respiratory complications from anesthesia and sedation and a potentially under-appreciated risk of neurocognitive dysfunction. Both animal and human studies support the detrimental effects of repeated anesthetic exposure on the developing brain. Although the studies in humans are less convincing of this risk, the Society of Pediatric Anesthesia jointly with SmartTots provided a consensus statement on the use of anesthetic and sedative drugs in infants and toddlers when speaking to families. (www.pedsanesthesia.org; http://smarttots.org/wp-content/uploads/2015/10/ConsensusStatementV910.5.2015.pdf). An excerpt of the statement is "Concerns regarding the unknown risk of anesthetic exposure to your child's brain development must be weighed against the potential harm associated with cancelling or delaying a needed procedure. Each child's care must be evaluated individually based on age, type, and urgency of the procedure and other health factors. This review provides a summary of the current evidence regarding anesthesia-induced neurotoxicity and the developing brain and its implications for children with congenital heart disease.

Congenital cardiac anomalies and white matter injury

Cardiac abnormalities are the most common birth defects. Derangement of circulatory flow affects many vital organs; without proper supply of oxygenated blood, the brain is particularly vulnerable. Although surgical interventions have greatly reduced mortality rates, patients often suffer an array of neurological deficits throughout life. Neuroimaging provides a macroscopic assessment of brain injury and has shown that white matter (WM) is at risk. Oligodendrocytes and myelinated axons have been identified as major targets of WM injury, but still little is known about how congenital heart anomalies affect the brain at the cellular level. Further integration of animal model studies and clinical research will define novel therapeutic targets and new standards of care to prevent developmental delay associated with cardiac abnormalities.

All this monitoring…what's necessary, what's not?

The goal of perioperative monitoring is to aid the clinician in optimizing care to achieve the best possible survival with the lowest possible morbidity. Ideally, we would like to have monitoring that can rapidly and accurately identify perturbations in circulatory well-being that would permit timely intervention and allow for restoration before the patient is damaged. The evidence to support the use of our standard monitoring strategies (continuous electrocardiography, blood pressure, central venous pressure, oxygen saturation and capnography) is based on expert opinion, case series, or at best observational studies. While these monitoring parameters will identify life-threatening events, they provide no direct information concerning the oxygen economy of the patient. Nevertheless, they are mandated by professional societies representing specialists in cardiac disease, critical care, and anesthesiology. Additional non-routine monitoring strategies that provide data concerning the body's oxygen economy, such as venous saturation monitoring and near infrared spectroscopy, have shown promise in prospective observational studies in managing these complex groups of patients. Ideally, high-level evidence would be required before adopting these newer strategies, but in the absence of new funding sources and the challenges of the wide variation in practice patterns between centers, this seems unlikely. The evidence supporting the current standard perioperative monitoring strategies will be reviewed. In addition, evidence supporting non-routine monitoring strategies will be reviewed and their potential for added benefit assessed.

Innominate artery cannulation and antegrade cerebral perfusion for aortic arch reconstruction in infants and children

PURPOSE

Innominate artery cannulation has been widely adopted as a means to perform aortic arch reconstruction with continuous cerebral perfusion in the newborn. Although this technique has been subsequently utilized in infants and children, there is currently no data regarding the safety or efficacy in these older children. The purpose of this study was to review our experience with innominate artery cannulation for aortic arch reconstruction in patients beyond the neonatal period.

METHODS

This was a retrospective review of 42 infants and children who underwent aortic arch reconstruction using the technique of innominate artery cannulation with continuous cerebral perfusion. Of these procedures, 29 (69%) were primary arch reconstructions, while 13 (31%) were aortic arch reoperations. The median age at surgery was 8 months, and 22 patients underwent concomitant intracardiac repairs.

RESULTS

There was no operative mortality in this cohort of 42 patients undergoing aortic arch reconstruction. There was also no overt evidence of neurologic injury. Specifically, none of the patients demonstrated a neurologic deficit, clinical seizure, or unexpected delay in regaining a normal state of consciousness. The median duration of antegrade cerebral perfusion was 34 minutes. The median duration of hospital stay was 11 days. No patient required reoperation on the aortic arch with a median of 45-month follow-up.

CONCLUSIONS

Innominate artery cannulation is a safe and effective technique for aortic arch reconstruction in nonneonates. We conclude that antegrade cerebral perfusion is a useful technique for aortic arch reconstruction in this patient population.

Effects of preoperative hypoxia on white matter injury associated with cardiopulmonary bypass in a rodent hypoxic and brain slice model

BACKGROUND

White matter (WM) injury is common after cardiopulmonary bypass or deep hypothermic circulatory arrest in neonates who have cerebral immaturity secondary to in utero hypoxia. The mechanism remains unknown. We investigated effects of preoperative hypoxia on deep hypothermic circulatory arrest-induced WM injury using a combined experimental paradigm in rodents.

METHODS

Mice were exposed to hypoxia (prehypoxia). Oxygen-glucose deprivation was performed under three temperatures to simulate brain conditions of deep hypothermic circulatory arrest including ischemia-reperfusion/reoxygenation under hypothermia.

RESULTS

WM injury in prenormoxia was identified after 35 °C-oxygen-glucose deprivation. In prehypoxia, injury was displayed in all groups. Among oligodendrocyte stages, the preoligodendrocyte was the most susceptible, while the oligodendrocyte progenitor was resistant to insult. When effects of prehypoxia were assessed, injury of mature oligodendrocytes and oligodendrocyte progenitors in prehypoxia significantly increased as compared with prenormoxia, indicating that mature oligodendrocytes and progenitors that had developed under hypoxia had greater vulnerability. Conversely, damage of oligodendrocyte progenitors in prehypoxia were not identified after 15 °C-oxygen-glucose deprivation, suggesting that susceptible oligodendrocytes exposed to hypoxia are protected by deep hypothermia.

CONCLUSION

Developmental alterations due to hypoxia result in an increased WM susceptibility to injury. Promoting WM regeneration by oligodendrocyte progenitors after earlier surgery using deep hypothermia is the most promising approach for successful WM development in congenital heart disease patients.

Anesthesia and the developing brain: relevance to the pediatric cardiac surgery

Anesthetic neurotoxicity has been a hot topic in anesthesia for the past decade. It is of special interest to pediatric anesthesiologists. A subgroup of children potentially at greater risk for anesthetic neurotoxicity, based on a prolonged anesthetic exposure early in development, are those children receiving anesthesia for surgical repair of congenital heart disease. These children have a known risk of neurologic deficit after cardiopulmonary bypass for surgical repair of congenital heart disease. Yet, the type of anesthesia used has not been considered as a potential etiology for their neurologic deficits. These children not only receive prolonged anesthetic exposure during surgical repair, but also receive repeated anesthetic exposures during a critical period of brain development. Their propensity to abnormal brain development, as a result of congenital heart disease, may modify their risk of anesthetic neurotoxicity. This review article provides an overview of anesthetic neurotoxicity from the perspective of a pediatric cardiac anesthesiologist and provides insight into basic science and clinical investigations as it relates to this unique group of children who have been studied over several decades for their risk of neurologic injury.