Improving On-Time Starts for Pediatric Cardiac MRI.

PURPOSE: Delayed start times for cardiac MRI examinations have resulted in longer patient fasts, extended wait times, and poor synchronization of anesthesia induction and contrast administration. The aim of this work was to improve on-time start rates from an initial baseline of 10%. METHODS: A multidisciplinary team comprising members of the cardiac and radiology services used the Realizing Improvement Through Team Empowerment methodology to target the root causes of the delays and enhance workflow. The main factors identified as contributing to examination delays were late patient arrival, variations in patient preparation time, unavailability of equipment, and inefficient scheduling processes. RESULTS: The implementation of various interventions, such as the use of standardized appointment scripts, ensuring timely patient preparation, and ensuring the availability of equipment when required, resulted in an increase in on-time start rates for cardiac MRI examinations to 34%. CONCLUSIONS: The study's systematic approach proved to be valuable in both understanding and resolving the identified problems. Through the continuous application of plan-do-study-act cycles, the authors effectively pinpointed obstacles and tested multiple potential measures to overcome them. This approach made it possible to comprehend the issue and to implement targeted interventions to address it.

Impaired Maternal-Fetal Environment and Risk for Preoperative Focal White Matter Injury in Neonates With Complex Congenital Heart Disease.

Background Infants with congenital heart disease (CHD) are at risk for white matter injury (WMI) before neonatal heart surgery. Better knowledge of the causes of preoperative WMI may provide insights into interventions that improve neurodevelopmental outcomes in these patients. Methods and Results A prospective single-center study of preoperative WMI in neonates with CHD recorded data on primary cardiac diagnosis, maternal-fetal environment (MFE), delivery type, subject anthropometrics, and preoperative care. Total maturation score and WMI were assessed, and stepwise logistic regression modeling selected risk factors for WMI. Among subjects with severe CHD (n=183) who received a preoperative brain magnetic resonance imaging, WMI occurred in 40 (21.9%) patients. WMI prevalence (21.4%-22.1%) and mean volumes (119.7-160.4 mm3) were similar across CHD diagnoses. Stepwise logistic regression selected impaired MFE (odds ratio [OR], 2.85 [95% CI, 1.29-6.30]), male sex (OR, 2.27 [95% CI, 1.03-5.36]), and older age at surgery/magnetic resonance imaging (OR, 1.20 per day [95% CI, 1.03-1.41]) as risk factors for preoperative WMI and higher total maturation score values (OR, 0.65 per unit increase [95% CI, 0.43-0.95]) as protective. A quarter (24.6%; n=45) of subjects had ≥1 components of impaired MFE (gestational diabetes [n=12; 6.6%], gestational hypertension [n=11; 6.0%], preeclampsia [n=2; 1.1%], tobacco use [n=9; 4.9%], hypothyroidism [n=6; 3.3%], and other [n=16; 8.7%]). In a subset of 138 subjects, an exploratory analysis of additional MFE-related factors disclosed other potential risk factors for WMI. Conclusions This study is the first to identify impaired MFE as an important risk factor for preoperative WMI. Vulnerability to preoperative WMI was shared across CHD diagnoses.

Association of Ongoing Cerebral Oxygen Extraction During Deep Hypothermic Circulatory Arrest With Postoperative Brain Injury.

Cardiac surgery utilizing circulatory arrest is most commonly performed under deep hypothermia (∼18°C) to suppress tissue oxygen demand and provide neuroprotection during operative circulatory arrest. Studies investigating the effects of deep hypothermic circulatory arrest (DHCA) on neurodevelopmental outcomes of patients with congenital heart disease give conflicting results. Here, we address these issues by quantifying changes in cerebral oxygen saturation, blood flow, and oxygen metabolism in neonates during DHCA and investigating the association of these changes with postoperative brain injury. Neonates with critical congenital heart disease undergoing DHCA were recruited for continuous intraoperative monitoring of cerebral oxygen saturation (ScO2) and an index of cerebral blood flow (CBFi) using 2 noninvasive optical techniques, diffuse optical spectroscopy (DOS) and diffuse correlation spectroscopy (DCS). Pre- and postoperative brain magnetic resonance imaging (MRI) was performed to detect white matter injury (WMI). Fifteen neonates were studied, and 11/15 underwent brain MRI. During DHCA, ScO2 decreased exponentially in time with a median decay rate of -0.04 min-1. This decay rate was highly variable between subjects. Subjects who had larger decreases in ScO2 during DHCA were more likely to have postoperative WMI (P = 0.02). Cerebral oxygen extraction persists during DHCA and varies widely from patient-to-patient. Patients with a higher degree of oxygen extraction during DHCA were more likely to show new WMI in postoperative MRI. These findings suggest cerebral oxygen extraction should be monitored during DHCA to identify patients at risk for hypoxic-ischemic injury, and that current commercial cerebral oximeters may underestimate cerebral oxygen extraction.

Preoperative cerebral hemodynamics from birth to surgery in neonates with critical congenital heart disease.

BACKGROUND: Hypoxic-ischemic white matter brain injury commonly occurs in neonates with critical congenital heart disease. Recent work has shown that longer time to surgery is associated with increased risk for this injury. In this study we investigated changes in perinatal cerebral hemodynamics during the transition from fetal to neonatal circulation to ascertain mechanisms that might underlie this risk. METHODS: Neonates with either transposition of the great arteries (TGA) or hypoplastic left heart syndrome (HLHS) were recruited for preoperative noninvasive optical monitoring of cerebral oxygen saturation, cerebral oxygen extraction fraction, and cerebral blood flow using diffuse optical spectroscopy and diffuse correlation spectroscopy, 2 noninvasive optical techniques. Measurements were acquired daily from day of consent until the morning of surgery. Temporal trends in these measured parameters during the preoperative period were assessed with a mixed effects model. RESULTS: Forty-eight neonates with TGA or HLHS were studied. Cerebral oxygen saturation was significantly and negatively correlated with time, and oxygen extraction fraction was significantly and positively correlated with time. Cerebral blood flow did not significantly change with time during the preoperative period. CONCLUSIONS: In neonates with TGA or HLHS, increasing cerebral oxygen extraction combined with an abnormal cerebral blood flow response during the time between birth and heart surgery leads to a progressive decrease in cerebral tissue oxygenation The results support and help explain the physiological basis for recent studies that show longer time to surgery increases the risk of acquiring white matter injury.

Systemic Atrioventricular Valve Excision and Ventricular Assist Devices in Pediatric Patients.

BACKGROUND: Continuous-flow ventricular assist devices (CF VADs) designed for adults are increasingly used in pediatric patients. However, there is greater risk of device inflow obstruction as a result of size and anatomy. METHODS: We reviewed all cases of systemic atrioventricular valve (AVV) excision with HeartWare HVAD (HeartWare, Framingham, MA) implantation in the systemic ventricle performed at our institution from November 2015 to May 2016. RESULTS: AVV excision with CF VAD implantation was undertaken in 3 patients. Patient 1 was palliated in infancy, resulting in biventricular physiology with a systemic right ventricle, and presented at age 15 years with worsening ventricular dysfunction. After CF VAD implantation in the systemic ventricle and discharge to home, tricuspid valve obstruction to VAD inflow developed, and the patient and underwent tricuspid valve excision on postoperative day 52. Patients 2 and 3 were aged younger than 4 years, with a body surface area of 0.62 m2 and 0.58 m2, respectively, and had undergone Fontan palliation, with subsequent systemic ventricular dysfunction and AVV regurgitation. In both Fontan patients, the CF VAD was implanted in the right atrium with simultaneous excision of the AVV. None have had evidence of elevated atrial pressures or recalcitrant pulmonary edema. At a mean follow-up of 359 days (range, 304 to 422 days), there have been no concerns for inflow obstruction or low flow. CONCLUSIONS: CF VAD implantation with AVV excision can successfully support complex pediatric patients in a wide range of size and anatomy (small chambers, systemic right ventricles). This technique may allow for CF VAD implantation in patients previously deemed too small for such support.

Surgical and Catheter-Based Reinterventions Are Common in Long-Term Survivors of the Fontan Operation.

BACKGROUND: There are limited follow-up studies examining surgical and catheter-based reinterventions in long-term survivors of the Fontan operation. METHODS AND RESULTS: All 773 patients who underwent Fontan at our institution between 1992 and 2009 were retrospectively reviewed. Current information regarding post-Fontan intervention was available for 70%. By 20 years after Fontan, 65% of patients had experienced either surgical or transcatheter intervention. The median time to first reintervention was 9.8 years. Freedom from reoperation was 69% at 15 years and 63% at 20 years. The most common operations were pacemaker placement and Fontan revision. Risk factors for pacemaker placement included systemic left ventricle (hazard ratio [HR], 2.2; P=0.006) and lateral tunnel Fontan (HR, 4.3; P=0.001). Freedom from interventional catheterization was 53% at 15 years and 50% at 20 years. The most common procedures performed were fenestration closure and pulmonary artery intervention. Catheter intervention for anatomic indications was associated with Fontan after 2002 (HR, 2.1; P=0.007), Norwood operation (HR, 2.3; P=0.001), and longer cardiopulmonary bypass time (HR, 1.1 per 10 minutes; P=0.001). Catheter intervention for physiological indications was associated with prolonged post-Fontan pleural drainage (HR, 4.0; P<0.001) and hypoplastic left heart syndrome (HR, 2.0; P=0.01). CONCLUSIONS: In this study of Fontan survivors, two thirds of patients required surgical or catheter-based reintervention by 20 years. Families should be counseled that the Fontan is typically not the final stage of single-ventricle palliation.

Long-Term Outcomes of Pediatric Cardiac Patients Supported by Extracorporeal Membrane Oxygenation.

OBJECTIVE: Extracorporeal membrane oxygenation is an important form of short-term mechanical support in children with cardiac disease, but information on long-term outcomes and quality of life is limited. The primary objective of this study was to determine the long-term outcomes of children previously supported by extracorporeal membrane oxygenation for cardiac etiologies. DESIGN: A retrospective analysis was performed on patients with cardiac disease managed with extracorporeal membrane oxygenation between January 1, 1995, and December 31, 2012, at the Children's Hospital of Philadelphia. Survivors completed patient- and parent-reported verbal and written surveys, and univariate analyses assessed risk factors for long-term outcomes. SETTING: Tertiary-care children's hospital. PATIENTS: Patients with cardiac disease managed with extracorporeal membrane oxygenation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Over 18 years, 396 patients were managed with extracorporeal membrane oxygenation with 43% survival to discharge. The median age at cannulation was 78 days. The majority had congenital heart disease (86%), surgery prior to extracorporeal membrane oxygenation (71%), and cardiopulmonary arrest as the primary extracorporeal membrane oxygenation indication (53%). With 6-year median follow-up, 66% are known to be deceased, including 38 deaths after hospital discharge. Among survivors at discharge, 65 (38%) completed the phone survey, and 33 (19%) completed the written survey. Negative clinical outcomes, defined as having at least significant physical limitations or "fair" or "poor" health, were present in 18% of patients. No patient- or extracorporeal membrane oxygenation-related variables were associated with negative outcomes in univariate analyses. There were significantly lower self-reported and parent-reported written Pediatric Quality of Life Inventory quality of life scores in children compared with healthy individual normative data but no differences in adolescents. CONCLUSIONS: In this series of pediatric cardiac patients supported by extracorporeal membrane oxygenation, mortality was 66% with 6-year median follow-up. The majority reported positive outcomes with respect to health and physical limitations, but children reported lower quality of life compared with healthy individuals.

Effect of Fontan-Associated Morbidities on Survival With Intact Fontan Circulation.

Although survival after the Fontan operation has improved, little is known about the burden of major medical morbidities associated with the modern total cavopulmonary connection (TCPC). A total of 773 consecutive patients who underwent a first Fontan operation at our institution between 1992 and 2009 were retrospectively reviewed. All subjects underwent TCPC (53% lateral tunnel, 47% extracardiac conduit). Median length of follow-up was 5.3 years (interquartile range 1.4 to 11.2), and 30% had follow-up >10 years. Freedom from a composite medical morbidity outcome (protein-losing enteropathy, plastic bronchitis, serious thromboembolic event, or tachyarrhythmia) was 47% at 20 years (95% confidence interval [CI] 38 to 55). Independent risk factors for morbidity included pre-Fontan atrioventricular valve regurgitation (hazard ratio [HR] 1.7, 95% CI 1.2 to 2.4, p = 0.001), pleural drainage >14 days (HR 1.5, 95% CI 1.01 to 2.2, p = 0.04), and longer cross-clamp time (HR 1.2 per 10 minutes, 95% CI 1.06 to 1.3, p = 0.004) at the time of TCPC. Surgical era, Fontan type, and ventricular morphology were not associated with the composite outcome. Presence of Fontan-associated morbidity was associated with a 36-fold increase in the risk of subsequent Fontan takedown, heart transplantation, or death (95% CI 17 to 76, p <0.001). For patients without any component of the composite outcome, freedom from Fontan failure was 98% at 20 years (95% CI 96 to 99). Medical morbidities after TCPC are common and significantly reduce the longevity of the Fontan circulation. However, for those patients who remain free from the composite morbidity outcome, 20-year survival with intact Fontan circulation is encouraging.

Long-term survival after the Fontan operation: Twenty years of experience at a single center.

OBJECTIVE: Existing studies of patients palliated with the Fontan operation are limited by heterogeneous patient populations and incomplete follow-up. This study aimed to describe long-term post-Fontan survival in a modern patient cohort. METHODS: All 773 patients who underwent a first Fontan operation at our institution between 1992 and 2009 were reviewed. The primary outcome was the composite endpoint of Fontan takedown, heart transplantation, or death before 2013. RESULTS: Follow-up rate was 99.2%. Survival with intact Fontan circulation was 94% at 1 year (95% confidence interval [95% CI], 92%-95%), 90% at 10 years (95% CI, 88%-92%), 85% at 15 years (95% CI, 82%-88%), and 74% at 20 years (95% CI, 67%-80%). Distinct risk factors were identified for early (≤1 year) and late composite outcomes. Independent risk factors for early outcome included prolonged pleural drainage (hazard ratio [HR], 4.4; P < .001), intensive care unit stay >1 week (HR, 2.4; P < .001), Fontan before 1997 (HR, 3.3; P < .001), preoperative atrioventricular valve regurgitation (HR, 2.0; P < .001), and longer crossclamp time (HR, 1.3 per 10 minutes; P < .001). Late outcome was predicted by atrioventricular valve regurgitation prior to Fontan (HR, 2.0; P ≤ .001), and post-Fontan ICU stay >1 week (HR, 2.4; P < .001). CONCLUSIONS: Long-term mortality after Fontan operation remains substantial. Risk factors for death or loss of Fontan circulation differ between the early and late postoperative periods. Long-term survival has not improved appreciably over the last decade, suggesting that alternatives to the Fontan are warranted.

Neurological Injury and Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction.

BACKGROUND: Patients with a single ventricle experience a high rate of brain injury and adverse neurodevelopmental outcome; however, the incidence of brain abnormalities throughout surgical reconstruction and their relationship with cerebral blood flow, oxygen delivery, and carbon dioxide reactivity remain unknown. METHODS: Patients with a single ventricle were studied with magnetic resonance imaging scans immediately prior to bidirectional Glenn (pre-BDG), before Fontan (BDG), and then 3 to 9 months after Fontan reconstruction. RESULTS: One hundred sixty-eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age, 4.8±1.7 months), 118 BDG (2.9±1.4 years), and 54 after Fontan (2.4±1.0 years). Nonacute ischemic white matter changes on T2-weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontan compared with pre-BDG patients (P<0.05). BDG patients had significantly higher cerebral blood flow than did Fontan patients. The odds of discovering brain injury with adjustment for surgical stage as well as ≥2 coexisting lesions within a patient decreased (63%-75% and 44%, respectively) with increasing amount of cerebral blood flow (P<0.05). In general, there was no association of oxygen delivery (except for ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury. CONCLUSIONS: Significant brain abnormalities are commonly present in patients with a single ventricle, and detection of these lesions increases as children progress through staged surgical reconstruction, with multiple coexisting lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater cerebral blood flow than did Fontan patients and that an inverse association exists of various indexes of cerebral blood flow with these brain lesions. However, CO2 reactivity and oxygen delivery (with 1 exception) were not associated with brain lesion development. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02135081.

Mechanical Circulatory Support as Bridge to Transplantation for the Failing Single Ventricle.

BACKGROUND: Circulatory failure necessitating cardiac transplantation will ultimately develop in many patients with functional single-ventricle physiology. Interest in the use of mechanical circulatory support (MCS) in this population is growing. METHODS: This was a retrospective case series of patients with functional single-ventricle physiology who underwent MCS with a ventricular assist device or a total artificial heart as a bridge to cardiac transplantation between January 2006 and December 2014. Baseline demographics, intraoperative data, postoperative complications, and outcome data were collected from the medical record. RESULTS: MCS was used in 5 patients: HeartWare ventricular assist device (HeartWare International, Framingham, MA) in 1 patient, SynCardia total artificial heart (SynCardia Systems, Tucson, AZ) in 1, Thoratec Paracorporeal ventricular assist device (Thoratec Corp, Pleasanton, CA) in 1, and the Berlin Heart EXCOR (Berlin Heart Inc, The Woodlands, TX) in 2. The mean age at MCS was 12 ± 8 years. There were 2 early deaths at 12 and 28 days after MCS: 1 patient died of multiorgan system failure and 1 of neurologic injury. Overall, neurologic complications occurred in 3 patients (60%), and 1 patient (20%) required renal replacement therapy. Three patients (60%) underwent successful cardiac transplantation. The median time on the waiting list was 59 days (interquartile range, 18 to 126 days), and the median duration of MCS was 60 days (interquartile range, 28 to 93 days). At the time of transplant, all 3 patients were ambulatory, without the need for mechanical ventilation, and end-organ dysfunction had resolved. The 3 patients who received transplants were discharged from the hospital and were alive at an average follow-up of 9 ± 14 months. CONCLUSIONS: MCS can be successfully used as a bridge to transplantation in patients with a failing single-ventricle circulation. Use of MCS can allow for resolution of end-organ dysfunction and rehabilitation, leading to improved outcomes in this difficult population.

Relationship of cerebral blood flow to aortic-to-pulmonary collateral/shunt flow in single ventricles.

OBJECTIVE: Patients with single ventricle can develop aortic-to-pulmonary collaterals (APCs). Along with systemic-to-pulmonary artery shunts, these structures represent a direct pathway from systemic to pulmonary circulations, and may limit cerebral blood flow (CBF). This study investigated the relationship between CBF and APC flow on room air and in hypercarbia, which increases CBF in patients with single ventricle. METHODS: 106 consecutive patients with single ventricle underwent 118 cardiac magnetic resonance (CMR) scans in this cross-sectional study; 34 prior to bidirectional Glenn (BDG) (0.50±0.30 years old), 50 prior to Fontan (3.19±1.03 years old) and 34 3-9 months after Fontan (3.98±1.39 years old). Velocity mapping measured flows in the aorta, cavae and jugular veins. Analysis of variance (ANOVA) and multiple linear regression were used. Significance was p<0.05. RESULTS: A strong inverse correlation was noted between CBF and APC/shunt both on room air and with hypercarbia whether CBF was indexed to aortic flow or body surface area, independent of age, cardiopulmonary bypass time, Po2 and Pco2 (R=-0.67--0.70 for all patients on room air, p<0.01 and R=-0.49--0.90 in hypercarbia, p<0.01). Correlations were not different between surgical stages. CBF was lower, and APCs/shunt flow was higher prior to BDG than in other stages. CONCLUSIONS: There is a strong inverse relationship between CBF and APC/shunt flow in patients with single ventricle throughout surgical reconstruction on room air and in hypercarbia independent of other factors. We speculate that APC/shunt flow may have a negative impact on cerebral development and neurodevelopmental outcome. Interventions on APC may modify CBF, holding out the prospect for improving neurodevelopmental trajectory. TRIAL REGISTRATION NUMBER: NCT02135081.

Time to surgery and preoperative cerebral hemodynamics predict postoperative white matter injury in neonates with hypoplastic left heart syndrome.

OBJECTIVE: Hypoxic-ischemic white mater brain injury commonly occurs in neonates with hypoplastic left heart syndrome (HLHS). Approximately one half of HLHS survivors will exhibit neurobehavioral symptoms believed to be associated with this injury, although the exact timing of the injury is unknown. METHODS: Neonates with HLHS were recruited for pre- and postoperative monitoring of cerebral oxygen saturation, cerebral oxygen extraction fraction, and cerebral blood flow using 2 noninvasive optical-based techniques: diffuse optical spectroscopy and diffuse correlation spectroscopy. Anatomic magnetic resonance imaging was performed before and approximately 1 week after surgery to quantify the extent and timing of the acquired white matter injury. The risk factors for developing new or worsened white matter injury were assessed using uni- and multivariate logistic regression. RESULTS: A total of 37 neonates with HLHS were studied. On univariate analysis, neonates who developed a large volume of new, or worsened, postoperative white matter injury had a significantly longer time to surgery (P=.0003). In a multivariate model, a longer time between birth and surgery, delayed sternal closure, and greater preoperative cerebral blood flow were predictors of postoperative white matter injury. Additionally, a longer time to surgery and greater preoperative cerebral blood flow on the morning of surgery correlated with lower cerebral oxygen saturation (P=.03 and P=.05, respectively) and greater oxygen extraction fraction (P=.05 for both). CONCLUSIONS: A longer time to surgery was associated with new postoperative white matter injury in otherwise healthy neonates with HLHS. The results suggest that earlier Norwood palliation might decrease the likelihood of acquiring postoperative white matter injury.

Brain magnetic resonance immediately before surgery in single ventricles and surgical postponement.

BACKGROUND: Single-ventricle patients undergoing surgical reconstruction experience a high rate of brain injury. Incidental findings on preoperative brain scans may result in safety considerations involving hemorrhage extension during cardiopulmonary bypass that result in surgical postponement. METHODS: Single-ventricle patients were studied with brain scans immediately preoperatively, as part of a National Institutes of Health study, and were reviewed by neuroradiology immediately before cardiopulmonary bypass. RESULTS: Of 144 consecutive patients recruited into the project, 33 were studied before stage I (3.7±1.8 days), 34 before bidirectional Glenn (5.8±0.5 months), and 67 before Fontan (3.3±1.1 years) operations. Six operations (4.5%), 2 before stage I, 3 before bidirectional Glenn, and 1 before Fontan, were postponed because of concerning findings on brain magnetic resonance imaging. Five were due to unexpected incidental findings of acute intracranial hemorrhage, and 1 was due to diffuse cerebellar cytotoxic edema; none who proceeded to operation had these lesions. Prematurity and genetic syndromes were not present in any patients with a postponed operation. Four of 4 before bidirectional Glenn/Fontan with surgical delays had hypoplastic left heart syndrome compared with 44 of 97 who did not (p=0.048). After observation and follow-up, all eventually had successful operations with bypass. CONCLUSIONS: Preoperative brain magnetic resonance imaging performed in children with single ventricles disclosed injuries in 4.5% leading to surgical delay; hemorrhagic lesions were most common and raised concerns for extension during the operation. The true risk of progression and need for delay of the operation due to heparinization associated with these lesions remains uncertain.

Successful use of the total artificial heart in the failing Fontan circulation.

Typical left ventricular assist devices are often ineffective for the failing Fontan circulation. We report the first successful use of a total artificial heart as a bridge to transplant in a patient who had previously undergone a Fontan operation.

Cerebral oxygen metabolism in neonates with congenital heart disease quantified by MRI and optics.

Neonatal congenital heart disease (CHD) is associated with altered cerebral hemodynamics and increased risk of brain injury. Two novel noninvasive techniques, magnetic resonance imaging (MRI) and diffuse optical and correlation spectroscopies (diffuse optical spectroscopy (DOS), diffuse correlation spectroscopy (DCS)), were employed to quantify cerebral blood flow (CBF) and oxygen metabolism (CMRO(2)) of 32 anesthetized CHD neonates at rest and during hypercapnia. Cerebral venous oxygen saturation (S(v)O(2)) and CBF were measured simultaneously with MRI in the superior sagittal sinus, yielding global oxygen extraction fraction (OEF) and global CMRO(2) in physiologic units. In addition, microvascular tissue oxygenation (StO(2)) and indices of microvascular CBF (BFI) and CMRO(2) (CMRO(2)(i)) in the frontal cortex were determined by DOS/DCS. Median resting-state MRI-measured OEF, CBF, and CMRO(2) were 0.38, 9.7 mL/minute per 100 g and 0.52 mL O(2)/minute per 100 g, respectively. These CBF and CMRO(2) values are lower than literature reports for healthy term neonates (which are sparse and quantified using different methods) and resemble values reported for premature infants. Comparison of MRI measurements of global S(v)O(2), CBF, and CMRO(2) with corresponding local DOS/DCS measurements demonstrated strong linear correlations (R(2)=0.69, 0.67, 0.67; P<0.001), permitting calibration of DOS/DCS indices. The results suggest that MRI and optics offer new tools to evaluate cerebral hemodynamics and metabolism in CHD neonates.

Risk factors for preoperative periventricular leukomalacia in term neonates with hypoplastic left heart syndrome are patient related.

BACKGROUND: Preoperative brain injury is common in neonates with complex congenital heart disease. Increasing evidence suggests a complex interaction of prenatal and postnatal risk factors for development of brain white matter injury, called periventricular leukomalacia (PVL), in neonates with complex congenital heart disease. To date, there remains a limited understanding of the risk factors contributing to preoperative PVL in hypoplastic left heart syndrome (HLHS). METHODS: Neonates with HLHS or HLHS variants from 3 prospective magnetic resonance imaging studies (2003-2010) were selected for this cohort. Preoperative brain magnetic resonance imaging was performed the morning of the surgery. Stepwise multilogistic regression of patient characteristics, mode of delivery (cesarean section vs vaginal), time of diagnosis (prenatal vs postnatal), HLHS subtypes, brain total maturation score, time to surgery, individual averaged daily preoperative blood gases, and complete blood cell count values was used to determine significant associations. RESULTS: A total of 57 neonates with HLHS were born at 38.7 ± 2.3 weeks; 86% (49/57) had a prenatal diagnosis, with 31% (18/57) delivered by cesarean section. HLHS with aortic atresia (AA) was common in this cohort, 71% (41/57). Preoperative PVL was identified in 19% (11/57). Male patients with AA (P = .004) were at higher risk for PVL. Lower total brain maturation score was also identified as a strong predictor for preoperative PVL (P = .005). CONCLUSIONS: In neonates with HLHS, nonmodifiable patient-related factors, including male sex with AA (lack of antegrade blood flow) and lower total brain maturation score, placed neonates at the greatest risk for preoperative white matter injury.

Sodium bicarbonate causes dose-dependent increases in cerebral blood flow in infants and children with single-ventricle physiology.

BACKGROUND: Sodium bicarbonate (NaHCO3) is a common treatment for metabolic acidemia; however, little definitive information exists regarding its treatment efficacy and cerebral hemodynamic effects. This pilot observational study quantifies relative changes in cerebral blood flow (ΔrCBF) and oxy- and deoxyhemoglobin concentrations (ΔHbO2 and ΔHb) due to bolus administration of NaHCO3 in patients with mild base deficits. METHODS: Infants and children with hypoplastic left heart syndrome (HLHS) were enrolled before cardiac surgery. NaHCO3 was given as needed for treatment of base deficit. Diffuse optical spectroscopies were used for 15 min postinjection to noninvasively monitor ΔHb, ΔHbO2, and ΔrCBF relative to baseline before NaHCO3 administration. RESULTS: Twenty-two anesthetized and mechanically ventilated patients with HLHS (aged 1 d to 4 y) received a median (interquartile range) dose of 1.1 (0.8, 1.8) mEq/kg NaHCO3 administered intravenously over 10-20 s to treat a median (interquartile range) base deficit of -4 (-6, -3) mEq/l. NaHCO3 caused significant dose-dependent increases in ΔrCBF; however, population-averaged ΔHb and ΔHbO2 as compared with those of controls were not significant. CONCLUSIONS: Dose-dependent increases in cerebral blood flow (CBF) caused by bolus administration of NaHCO3 are an important consideration in vulnerable populations wherein risk of rapid CBF fluctuations does not outweigh the benefit of treating a base deficit.

Transesophageal echocardiography probe insertion failure in infants undergoing cardiac surgery.

BACKGROUND: The use of intraoperative transesophageal echocardiography (iTEE) in neonates ≤4 kg has not been systematically described. We sought to describe the use of and determine risk factors for iTEE probe insertion failure in small infants. We also sought to develop an algorithm for predicting the likelihood of iTEE probe insertion failure. DESIGN: A retrospective chart review of all neonates ≤4 kg who underwent cardiac surgery at our institution from 12/2001 to 12/2006 was performed. Patients who underwent operations that did not typically require TEE were excluded. Risk factors for TEE probe insertion failure were assessed. RESULTS: Of 310 neonates who met the inclusion criteria, 219 (70%) underwent successful iTEE. Lower weight (P <.001), abnormal craniofacial anatomy (P =.03), prematurity (P =.015), and 22q11 deletion (P =.04) were independently associated with iTEE probe insertion failure. Stratified by weight, there was an 80% predicted probability of iTEE probe insertion failure for infants weighing: 2 kg with any two of the above risk factors and 3 kg with any three of the above risk factors. There was less than an 80% predicted likelihood of iTEE probe insertion failure for infants weighing 4 kg regardless of other risk factor status. CONCLUSIONS: iTEE can be successfully performed in the majority of neonates ≤4 kg undergoing cardiac surgery. However, there are identifiable risk factors for iTEE probe insertion failure. A weight-based algorithm may help determine neonates at risk for iTEE probe insertion failure. Smaller TEE probes may benefit this patient population.