Cerebral ventriculomegaly after the bidirectional Glenn (BDG) shunt: a single-institution retrospective analysis

Intracranial Pressure and Cerebral Hemodynamics in Infants Before and After Glenn Procedure

OBJECTIVES

This prospective cohort study aimed to investigate changes in intracranial pressure (ICP) and cerebral hemodynamics in infants with congenital heart disease undergoing the Glenn procedure, focusing on the relationship between superior vena cava pressure and estimated ICP.

DESIGN

A single-center prospective cohort study.

SETTING

The study was conducted in a cardiac center over 4 years (2019-2022).

PATIENTS

Twenty-seven infants with congenital heart disease scheduled for the Glenn procedure were included in the study, and detailed patient demographics and primary diagnoses were recorded.

INTERVENTIONS

Transcranial Doppler (TCD) ultrasound examinations were performed at three time points: baseline (preoperatively), postoperative while ventilated (within 24-48 hr), and at discharge. TCD parameters, blood pressure, and pulmonary artery pressure were measured.

MEASUREMENTS AND MAIN RESULTS

TCD parameters included systolic flow velocity, diastolic flow velocity (dFV), mean flow velocity (mFV), pulsatility index (PI), and resistance index. Estimated ICP and cerebral perfusion pressure (CPP) were calculated using established formulas. There was a significant postoperative increase in estimated ICP from 11 mm Hg (interquartile range [IQR], 10-16 mm Hg) to 15 mm Hg (IQR, 12-21 mm Hg) postoperatively (p = 0.002) with a trend toward higher CPP from 22 mm Hg (IQR, 14-30 mm Hg) to 28 mm Hg (IQR, 22-38 mm Hg) postoperatively (p = 0.1). TCD indices reflected alterations in cerebral hemodynamics, including decreased dFV and mFV and increased PI. Intracranial hemodynamics while on positive airway pressure and after extubation were similar.

CONCLUSIONS

Glenn procedure substantially increases estimated ICP while showing a trend toward higher CPP. These findings underscore the intricate interaction between venous pressure and cerebral hemodynamics in infants undergoing the Glenn procedure. They also highlight the remarkable complexity of cerebrovascular autoregulation in maintaining stable brain perfusion under these circumstances.

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.

Characterization of the Ejector Pump Performance for the Assisted Bidirectional Glenn Procedure

This study introduces an algebraic model informed by computational fluid dynamics (CFD) simulations to investigate the performance of the assisted bidirectional Glenn (ABG) operation on a broad range of conditions. The performance of this operation, as measured by the superior vena cava (SVC) pressure, depends on the nozzle area in its ejector pump and the patient’s pulmonary vascular resistance (PVR). Using the developed algebraic model to explore this two-dimensional parameter space shows that the ejector pump can create a pressure difference between the pulmonary artery and the SVC as high as 5 mmHg. The lowest SVC pressure is produced at a nozzle area that decreases linearly with the PVR such that, at PVR =4.2 (Wood units-m2), there is no added benefit in utilizing the ejector pump effect (optimal nozzle area is zero, corresponding to the bidirectional Glenn circulation). At PVR =2 (Wood units-m2), the SVC pressure can be lowered to less than 4 mmHg by using an optimal nozzle area of ≈2.5 mm2. Regardless of the PVR, adding a 2 mm2 nozzle to the baseline bidirectional Glenn boosts the oxygen saturation and delivery by at least 15%. The SVC pressure for that 2 mm2 nozzle remains below 14 mmHg for all PVRs less than 7 Wood units-m2. The mechanical efficiency of the optimal designs consistently remains below 30%, indicating the potential for improvement in the future. A good agreement is observed between the algebraic model and high-fidelity CFD simulations.

An Efficient Assisted Bidirectional Glenn Design With Lowered Superior Vena Cava Pressure for Stage-One Single Ventricle Patients

Recently, the assisted bidirectional Glenn (ABG) procedure has been proposed as an alternative to the modified Blalock-Taussig shunt (mBTS) operation for neonates with single-ventricle physiology. Despite success in reducing heart workload and maintaining sufficient pulmonary flow, the ABG also raised the superior vena cava (SVC) pressure to a level that may not be tolerated by infants. To lower the SVC pressure, we propose a modified version of the ABG (mABG), in which a shunt with a slit-shaped nozzle exit is inserted at the junction of the right and left brachiocephalic veins. The proposed operation is compared against the ABG, the mBTS, and the bidirectional Glenn (BDG) operations using closed-loop multiscale simulations. Both normal (2.3 Wood units-m2) and high (7 Wood units-m2) pulmonary vascular resistance (PVR) values are simulated. The mABG provides the highest oxygen saturation, oxygen delivery, and pulmonary flow rate in comparison to the BDG and the ABG. At normal PVR, the SVC pressure is significantly reduced below that of the ABG and the BDG (mABG: 4; ABG: 8; BDG: 6; mBTS: 3 mmHg). However, the SVC pressure remains high at high PVR (mABG: 15; ABG: 16; BDG: 12; mBTS: 3 mmHg), motivating an optimization study to improve the ABG hemodynamics efficiency for a broader range of conditions in the future. Overall, the mABG preserves all advantages of the original ABG procedure while reducing the SVC pressure at normal PVR.

Pattern of head circumference growth following bidirectional Glenn in infants with single ventricle heart disease

BACKGROUND

Infants with single ventricle congenital heart disease demonstrate increasing head growth after bidirectional Glenn; however, the expected growth trajectory has not been well described.

AIMS

1) We will describe the pattern of head circumference growth in the first year after bidirectional Glenn. 2) We will determine if head growth correlates with motor developmental outcomes approximately 12 months after bidirectional Glenn.

METHODS

Sixty-nine single ventricle patients underwent bidirectional Glenn between 2010 and 2016. Patients with structural brain abnormalities, grade III-IV intra-ventricular haemorrhage, significant stroke, or obstructive hydrocephalus were excluded. Head circumference and body weight measurements from clinical encounters were evaluated. Motor development was measured with Psychomotor Developmental Index of the Bayley Scales of Infant Development, Third Edition. Generalised estimating equations assessed change in head circumference z-scores from baseline (time of bidirectional Glenn) to 12 months post-surgery.

RESULTS

Mean age at bidirectional Glenn was 4.7 (2.3) months and mean head circumference z-score based on population-normed data was -1.13 (95% CI -1.63, -0.63). Head circumference z-score increased to 0.35 (95% CI -0.20, 0.90) (p < 0.0001) 12 months post-surgery. Accelerated head growth, defined as an increase in z-score of >1 from baseline to 12 months post-surgery, was present in 46/69 (66.7%) patients. There was no difference in motor Psychomotor Developmental Index scores between patients with and without accelerated head growth.

CONCLUSION

Single ventricle patients demonstrated a significant increase in head circumference after bidirectional Glenn until 10-12 months post-surgery, at which time growth stabilised. Accelerated head growth did not predict sub-sequent motor developmental outcomes.

Perioperative Assessment of Cerebral Oxygen Metabolism in Infants With Functionally Univentricular Hearts Undergoing the Bidirectional Cavopulmonary Connection

OBJECTIVES

The transition from single-ventricle lesions with surgically placed systemic-to-pulmonary artery shunt to the circulation following a bidirectional cavopulmonary connection results in higher pressure in the superior vena cava when compared with the preceding circulation. The aim of this study was to evaluate the impact of this transition on the perioperative cerebral oxygen metabolism.

DESIGN

Prospective observational cohort study.

SETTING

Pediatric critical care unit of a tertiary referral center.

PATIENTS

Sixteen infants after bidirectional cavopulmonary connection.

INTERVENTION

Cardiac surgery (bidirectional cavopulmonary connection).

MEASUREMENTS AND MAIN RESULTS

We measured regional cerebral oxygen saturation, amount of hemoglobin, blood flow velocity, and microperfusion immediately before, 12-24 hours, and 36-48 hours following bidirectional cavopulmonary connection. Based on these measurements, we calculated cerebral fractional tissue oxygen extraction and approximated cerebral metabolic rate of oxygen. Mean pressure in the superior vena cava increased significantly (8 vs 17 mm Hg; p < 0.001) following bidirectional cavopulmonary connection. Mean cerebral oxygen saturation increased from 49.0% (27.4-61.0) to 56.9% (39.5-64.0) (p = 0.008), whereas mean cerebral blood flow velocity decreased from 80.0 arbitrary units (61.9-93.0) to 67.3 arbitrary units (59.0-83.3) (p < 0.001). No change was found in the cerebral amount of hemoglobin and in the cerebral microperfusion. Mean cerebral fractional tissue oxygen extraction (0.48 [0.17-0.63] vs 0.30 [0.19-0.56]; p = 0.006) and approximated cerebral metabolic rate of oxygen (5.82 arbitrary units [2.70-8.78] vs 2.27 arbitrary units [1.19-7.35]; p < 0.001) decreased significantly.

CONCLUSIONS

Establishment of bidirectional cavopulmonary connection is associated with postoperative improvement in cerebral oxygen metabolism. Cerebral amount of hemoglobin did not increase, although creation of the bidirectional cavopulmonary connection results in significant elevation in superior vena cava pressure. Improvement in cerebral oxygen metabolism was due to lower cerebral blood flow velocity and stable microperfusion, which may indicate intact cerebral autoregulation.

Alterations in cerebral ventricle size in children with congenital heart disease

PURPOSE

Children with tetralogy of Fallot (TOF) and superior cavopulmonary anastomoses (SCPA) can have chronically elevated central venous pressure (CVP), which has been postulated to put patients at risk for cerebral ventriculomegaly. We aimed to examine cerebral ventricle size in children with these congenital heart lesions before and after surgery to determine how changes in CVP affect ventricle size.

METHODS

We reviewed the records of patients who underwent SCPA or TOF repair between 2006 and 2015. Patients with pre- or post-operative cranial imaging were included. Frontal-occipital (FO) horn ratios were calculated as measures of cerebral ventricle volume. Reported normal mean FO ratio is 0.37 ± 0.03. Patient characteristics including occipito-fronto circumference (OFC) and available CVP measurements were recorded. CVP, FO ratios, and OFC percentiles were compared using paired and unpaired t tests and Wilcoxon matched pairs signed-rank test as appropriate.

RESULTS

We reviewed 44 patients who underwent SCPA and 31 patients who underwent TOF repair who had cranial imaging studies available. In the 22 patients who underwent SCPA and had pre- and post-operative imaging, mean FO ratios significantly increased from 0.37 ± 0.03 to 0.40 ± 0.04 (P < 0.001). In contrast, in the seven patients with TOF with pre- and post-operative imaging, FO ratio was elevated at baseline and remains so after surgical repair, 0.43 ± 0.08 to 0.42 ± 0.08 (P = 0.65). Similar patterns were noted with OFC percentiles, which were significantly increased as compared to baseline after SCPA (P < 0.001) but were not significantly changed after TOF repair (P = 0.58). Finally, when available, preoperative and postoperative CVP measurements of all patients were examined, CVP increased in patients who underwent SCPA, from 6.5 ± 2 mmHg preoperatively to 9.1 ± 2.3 mmHg postoperatively (P < 0.001), while CVP remained statistically unchanged in patients who underwent TOF repair, 12.9 ± 3.3 mmHg preoperatively to 14.4 ± 3.1 mmHg postoperatively (P = 0.2).

CONCLUSION

Cerebral ventriculomegaly was observed in patients with SCPA and TOF, and the observed changes in FO ratio and OFC may be related, at least in part, to CVP.

Multiple echocardiography abnormalities associated with endoscopic third ventriculostomy failure

OBJECTIVE Although endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) has gained increasing prominence in the management of hydrocephalus caused by intraventricular hemorrhage of prematurity, the rates of long-term shunt independence remain low. Furthermore, limited evidence is available to identify infants who might benefit from the procedure. The authors tested the hypothesis that elevated venous pressure that results from comorbid cardiac disease might predispose patients to ETV/CPC failure and shunt dependence. METHODS A retrospective analysis was performed on a consecutive series of 48 infants with hydrocephalus who underwent ETV/CPC and also underwent preoperative echocardiography between 2007 and 2014. Comorbid cardiac abnormalities that are known to result in elevated right heart pressure were reviewed. Associations between ETV/CPC success and the presence of pulmonary hypertension, right ventricular hypertrophy, left-to-right shunting, ventricular septal defect, or patent ductus arteriosus were determined using multivariate logistic regression analysis. RESULTS Of the 48 children who met the inclusion criteria, ETV/CPC failed in 31 (65%). In univariate analysis, no single echocardiogram abnormality was associated with shunt failure, but the presence of 2 or more concurrent echocardiogram abnormalities was associated with ETV/CPC failure (17 [85%] of 20 vs 14 [50%] of 28, respectively; p = 0.018). In multivariate logistic regression analysis, when the authors adjusted for the child's ETV success score, the presence of 2 abnormalities remained independently associated with poor outcome (2 or more echocardiogram abnormalities, OR 0.13, 95% CI 0.01-0.7, p = 0.032; ETV success score, OR 1.1, 95% CI 1-1.2, p = 0.05). CONCLUSIONS In this study, cardiac abnormalities were inversely associated with the success of ETV/CPC in infants with hydrocephalus of prematurity. ETV/CPC might not be as efficacious in patients with significant cardiac anomalies. These results provide a basis for future efforts to stratify surgical candidacy for ETV/CPC on the basis of comorbid abnormalities. Proper cardiac physiological pressure monitoring might help elucidate the relationship between cardiac abnormalities and hydrocephalus.