Pediatric Cardiology

Delivery room oxygen physiology and respiratory interventions for newborns with cyanotic congenital heart disease.

Delivery room oxygen physiology and respiratory interventions for newborns with cyanotic congenital heart disease. Thomas AR, Ma AL, Weinberg DD, Huber M, Ades A, Rychik J, Foglia EE. J Perinatol. 2021 Mar 23. doi: 10.1038/s41372-021-01029-2. PMID: 33758390     Take-Home Points: In a single-center retrospective study of neonates born with cyanotic congenital heart disease, a comparison was made of the trends of oxygen saturations for the first ten minutes after birth between three physiologies – single ventricle physiology with critical aortic obstruction, single or double ventricle physiology with pulmonary outflow obstruction, and those with transposition of great arteries physiology (TGA) Infants with TGA physiology had lower pulse oximetry levels at all recorded time points (up to 10 min) when compared to those with ductal dependent systemic and pulmonary circulation. Infants with TGA physiology received supplemental oxygen therapy and respiratory interventions more frequently than the other groups. Majority of the infants had stable cardiovascular status with initially recorded heart rates of more than 100 beats per minute.     Commentary from Dr. Venu Amula (Salt Lake City, UT, USA), section editor of Pediatric & Fetal Cardiology Journal Watch:  Newborns with cyanotic congenital heart disease differ from normal neonates concerning oxygen saturations(SpO2). Their transition from fetal to neonatal physiology at birth is also different, and reference oxygen saturation trajectories and respiratory interventions needed have not been well established. In this study by AR Thomas et al., the authors characterize and trend SpO2 values at birth in neonates with cyanotic congenital heart disease. They also report the frequency and intensity of delivery room respiratory interventions in neonates during the birth transition. This single-center, retrospective study of all infants born at > or = 32 weeks GA with a prenatal diagnosis of cyanotic congenital heart disease at a quaternary pediatric care center with a Level IV neonatal care nursery. Based on fetal echocardiogram – the infants were grouped into three categories – those with single ventricle physiology with critical aortic obstruction (SV-CAO )leading to ductal dependent systemic circulation, those with critical pulmonary outflow obstruction ( CPO) with either single ventricle or two ventricles but ductal dependent pulmonary flow and the third group with transposition physiology (TGA) where the systemic and pulmonary circulations are in parallel. At birth for all infants, the standardized institution neonatal resuscitation guidelines were followed with anticipated goal saturations of 75-85% for neonates given their cyanotic heart lesion. The saturations were measured on the right hand to obtain preductal measurements. Interventions were indicated to maintain saturations in the goal range and provide supplemental oxygen therapy, continuous positive airway pressure, positive pressure ventilation, and endotracheal intubation. Delivery room interventions and minute-to-minute SpO2 values were compared across and between three diagnostic groups using standard statistical tests. Of 208 infants ≥32 weeks gestation with eligible prenatally diagnosed cardiac lesions born during the study period, 196 infants were included in the analyses of oxygen saturation and respiratory intervention data. The TGA group had lower pulse SpO2 values at each time point. Comparing each group separately to TGA showed significant differences in SpO2 values at each minute (all p < 0.01 for CPO v TGA and all p < 0.02 for SV-CAO v TGA). No significant differences were found in pairwise comparison of the SV-CAO group to CPO group (p > 0.05) in SpO2 values at each minute after birth. Infants with TGA physiology received supplemental oxygen and non-invasive respiratory interventions more frequently than the infants in the SV-CAO and the CPO groups (Table 3). Significantly more infants with TGA physiology underwent endotracheal intubation in the resuscitation suite (53%) and occurred at a median of 24 (IQR 18–35) minutes after birth.         This study attempts to analyze the trends of target oxygen saturation in children with cyanotic congenital heart disease immediately after birth. These infants represent a heterogeneous group of neonates, and even within the same physiology group, the spectrum of disease dictates the target oxygen saturation achieved. The interventions were performed to achieve the goal target oxygen saturations of 75-85% - and represent the current practice in most institutions, although the optimal saturations are not well known. The goal is to accept some degree of hypoxia to maintain adequate systemic perfusion. Though the study represents a single-center practice, this information is valuable to guide physicians in providing resuscitation to babies with known cyanotic heart disease. Smoothed conditional curves of the 25th, 50th, and 75th percentiles for pre-ductal SpO2 values for minutes 3–10 after birth were plotted for each diagnostic group and for comparison, the 25th, 50th, and 75th percentile values for SpO2 at each minute reported for infants without CCHD by Dawson et al.(1)             Dawson JA, Kamlin COF, Vento M, Wong C, Cole TJ, Donath SM, et al. Defining the reference range for oxygen saturation for infants after birth. Pediatrics. 2010;125:e1340–7.

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Comparison of Management Strategies for Neonates With Symptomatic Tetralogy of Fallot.

Goldstein BH, Petit CJ, Qureshi AM, McCracken CE, Kelleman MS, Nicholson GT, Law MA, Meadows JJ, Zampi JD, Shahanavaz S, Mascio CE, Chai PJ, Romano JC, Batlivala SP, Maskatia SA, Asztalos IB, Kamsheh AM, Healan SJ, Smith JD, Ligon RA, Pettus JA, Juma S, Raulston JEB, Hock KM, Pajk AL, Eilers LF, Khan HQ, Merritt TC, Canter M, Juergensen S, Rinderknecht FA, Bauser-Heaton H, Glatz AC. J Am Coll Cardiol. 2021 Mar 2;77(8):1093-1106. doi: 10.1016/j.jacc.2020.12.048. PMID: 33632484 Take-Home Points: In children with symptomatic Tetralogy of Fallot, needing neonatal intervention, a comparison made between those managed with staged repair (SR) vs. primary repair (PR) showed balanced results. Upon adjusting for patient factors, early mortality risk was higher in the PR group; however, the overall risk of death did not differ between treatment groups. Lesser neonatal morbidity was reported in the SR group. In contrast, the overall cumulative morbidity burden (combining the initial palliation and complete repair in the SR group) favored the primary repair group. Reintervention risk was higher in the SR group, but late reintervention risk (>3 months) and reintervention burden following definitive repair did not differ between groups. Both strategies have potential benefits, and hence an individualized case-based approach is warranted based on patient, procedural and institutional factors. Commentary from Dr. Venu Amula (Salt Lake City, UT, USA), section editor of Pediatric & Fetal Cardiology Journal Watch:  Tetralogy of Fallot (TOF) is a congenital heart disease with a spectrum of cyanosis based on the degree of right ventricular outflow tract obstruction. Neonates can be symptomatic early, with cyanosis needing an intervention. Early intervention in symptomatic neonates can be palliative – both surgical and transcatheter procedures to provide additional pulmonary blood flow, or some may consider primary repair of the intracardiac defect. In this study by Goldstein et al., the investigators seek to compare the two treatment strategies of staged repair (SP) ( initial palliation [IP] followed by complete repair [CP])  and Primary repair (PR). The authors performed a retrospective cohort study using a multicenter collaborative with good sample size and practice variability to compare outcomes adjusted for patient-level differences and reduce confounding by indication. Study subjects included all neonates with tetralogy of Fallot who underwent an initial intervention  < or = 30 days at the nine centers of the Congenital Cardiac Research Collaborative. The indication of intervention was cyanosis, ductal dependent pulmonary blood flow, or hyper cyanotic episodes. Cases with discontinuous pulmonary arteries, TOF associated with Atrioventricular canal, Absent Pulmonary Valve, and Major Aortopulmonary Collaterals were excluded. The index procedure ( Initial Palliation or Primary Repair ) was the exposure, with the primary outcome being death or heart transplantation. Secondary outcomes included in-hospital mortality, procedural and hospital complications, reinterventions, and other measures of morbidity. The five variables most likely associated with treatment strategy ( SR vs. PR) – center, preintervention mechanical ventilation, prematurity, DiGeorge syndrome, and presence of antegrade blood flow were used in a logistic regression model to estimate propensity scores. Inverse probability of treatment weighting using propensity scores was used to adjust for potential confounders between groups. The effect of treatment strategy on dichotomous outcomes was evaluated by logistic regression weighted by propensity score. Time-dependent outcomes were analyzed with survival analysis. The overall study cohort consisted of 572 patients, 230 treated with primary repair and 345 with initial palliation.     Adjusted comparison of the primary outcome of death ( none got transplanted in this cohort)  showed no difference in the overall hazard of death (HR: 0.82; 95% CI: 0.49 to 1.38; p = 0.459), although early mortality hazard (<4 months post-intervention) was lower in the SR group (HR: 0.5; 95% CI: 0.25 to 0.97; p =0.041). Propensity score-adjusted differences in continuous secondary outcomes of neonatal morbidities, including procedural complications, duration of mechanical ventilation and inotrope use, procedural support times (CPB, cross-clamp, anesthesia), and ICU LOS, remained lower in the SR group at the index procedure. As was the case in the observed data, the adjusted cumulative burden of the SR strategy was associated with greater exposure to procedural, ICU, and post-procedural secondary outcomes than in the PR group. Adjusted differences in the outcomes of in-hospital mortality and complications showed that the risk of in-hospital mortality was lower in the SR group at the index procedure (OR: 0.37; 95% CI: 0.15 to 0.88; p = 0.025) and again at definitive repair (OR: 0.25; 95% CI: 0.09 to 0.69; p = 0.008), but when the entirety of the SR strategy was compared with PR, there was no difference in the risk of in-hospital mortality between groups (OR: 0.57; 95% CI: 0.26 to 1.24; p = 0.16). Similarly, although components of the SR pathway demonstrated lower rates of complications, there were no differences in the rate of procedural complications (OR: 0.84;95%CI:0.6to1.19; p = 0.33) or hospital complications (OR: 1.13; 95% CI: 0.79 to 1.61; p =0.51) between the treatment groups when the cumulative therapeutic pathways were compared.   The authors tried to address the vital issue of comparing staged repair vs. primary repair in the setting of symptomatic neonates with tetralogy of Fallot. While a well-designed  Randomized Controlled Trial would make the treatment groups well balanced to make an unbiased comparison of two treatment strategies – the large sample size from a research collaborative gave the authors unique opportunity to apply statistical methodology to adjust patient differences and provide a meaningful comparison of outcomes.  Given that early mortality, neonatal morbidity, and procedural complications were lower in the SR group, whereas cumulative morbidity and reinterventions favored the PR group, the authors conclude that an individualized, case-based approach to the initial interventional strategy is warranted.

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Increases in oxygen saturation following discharge from Fontan palliation – an indicator of resolution of pulmonary arteriovenous malformations?

Increases in oxygen saturation following discharge from Fontan palliation - an indicator of resolution of pulmonary arteriovenous malformations? Van Galder H, Schaal AM, Feng M, Pan AY, Frommelt MA, Ginde S, Spearman AD. Cardiol Young. 2021 Mar 11:1-7. doi: 10.1017/S1047951121000913. PMID: 33691814   Take Home Points:   Pulmonary arteriovenous malformations in single ventricle congenital heart disease are poorly understood. Pulmonary arteriovenous malformations are variably diagnosed prior to Fontan palliation; however, all study groups had increased oxygen saturations after Fontan discharge, potentially indicating resolution of pulmonary arteriovenous malformations in all groups. The prevalence of pulmonary arteriovenous malformations pre-Fontan is likely underestimated.   Commentary from Dr. Manoj Gupta (New York, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch   Introduction: In single ventricle patients, intrapulmonary shunting through pulmonary arteriovenous malformations may develop, worsen, or regress after Fontan palliation and can variably impact oxygen saturation. The prevalence of pulmonary arteriovenous malformations in single ventricle CHD is variably reported – ranging from 15 to 100% depending on the specific cohort, diagnostic criteria, and follow-up duration.   The primary objective of this study was to determine whether pulmonary arteriovenous malformations are diagnosed more frequently before Fontan palliation in patients with heterotaxy syndrome compared to matched non-heterotaxy patients. Secondarily the authors sought to compare oxygen saturation changes after Fontan discharge as a clinical marker of resolution of pulmonary arteriovenous malformations.   Diagnosis of pulmonary arteriovenous malformations pre-Fontan was obtained by contrast echocardiogram using agitated saline (“bubble study”) or during cardiac catheterization. Severity of shunting was classified as negative (no bubbles entering the single ventricle), mild (occasional or few bubbles filling of the single ventricle), moderate (moderate filling of the single ventricle), or severe (complete opacification of the single ventricle)   Results   A total of 124 patients with single ventricle CHD and previous Fontan palliation were included in this study with 62 heterotaxy patients and 62 non-heterotaxy hypoplastic left heart syndrome controls. Of the 62 heterotaxy patients, 14 (22.6%) had an interrupted inferior cava vein.   Patients with heterotaxy and interrupted inferior cava vein were more likely to have a documented diagnosis of pulmonary arteriovenous malformations in their medical record prior to Fontan palliation (85.7%) compared to patients with heterotaxy and intact inferior caval vein (20.8%) and non-heterotaxy control (24.2%) (p < 0.01).  Using a linear mixed model, there was no difference in Pre-Fontan oxygen saturations among the three groups (heterotaxy: intact inferior caval vein 82.0 (78.0, 85.0)%, interrupted inferior caval vein 80.5 (77.0, 85.0)%; non-heterotaxy control 82.0 (79.0, 85.0)%   At Fontan discharge, the non-heterotaxy control group (90.0 (86.0, 94.0)%) increased their oxygen saturations more than both heterotaxy sub-groups (intact inferior caval vein 87.0 (83.0, 92.0)%, p < 0.01; interrupted inferior caval vein 84.0 (82.0, 86.0)%, p < 0.01), but there was no difference in oxygen saturation between the two heterotaxy sub-groups (p = 0.18).   At 3, 6, and 12 months post-Fontan, there was no difference in oxygen saturation among the three groups at each time point.   Discussion   In this study, patients with heterotaxy syndrome and non-heterotaxy hypoplastic left heart syndrome had variable diagnostic rates of pulmonary arteriovenous malformations pre-Fontan, yet all study groups had increases in oxygen saturation after Fontan discharge. This data indicate that pulmonary arteriovenous malformations are present prior to Fontan palliation and resolve after Fontan palliation for patients with and without heterotaxy syndrome. The specific patient factors that increase susceptibility to pulmonary arteriovenous malformations remain unknown. Despite a lack of consensus on the prevalence and optimal diagnostic criteria for pulmonary arteriovenous malformations, studies have repeatedly used increased oxygen saturations after Fontan discharge as a surrogate for resolution of pulmonary arteriovenous malformations.   In conclusion, our data indicate that pulmonary arteriovenous malformations are variably diagnosed prior to Fontan palliation. It remains unclear, though, if there are true differences in susceptibility to pulmonary arteriovenous malformations because patients with and without heterotaxy syndrome have increases in oxygen saturations throughout the first year after Fontan discharge. A quantitative, systematic approach to diagnosis and follow-up pulmonary arteriovenous malformations is needed to better understand pulmonary microvascular remodeling in single ventricle CHD.

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