Younger age at initiation of subcutaneous treprostinil is associated with better response in pediatric Group 1 pulmonary arterial hypertension.

Children with severe Group 1 pulmonary arterial hypertension (PAH) have an unpredictable response to subcutaneous treprostinil (TRE) therapy, which may be influenced by age, disease severity, or other unknown variables at time of initiation. In this retrospective single-center cohort study, we hypothesized that younger age at TRE initiation, early hemodynamic response (a decrease in pulmonary vascular resistance by ≥30% at follow-up catheterization), and less severe baseline hemodynamics (Rp:Rs < 1.1) would each be associated with better clinical outcomes. In 40 pediatric patients with Group I PAH aged 17 days-18 years treated with subcutaneous TRE, younger age (cut-off of 6-years of age, AUC 0.824) at TRE initiation was associated with superior 5-year freedom from adverse events (94% vs. 39%, p = 0.002), better WHO functional class (I or II: 88% vs. 39% p = 0.003), and better echocardiographic indices of right ventricular function at most recent follow-up. Neither early hemodynamic response nor less severe baseline hemodynamics were associated with better outcomes. Patients who did not have a significant early hemodynamic response to TRE by first follow-up catheterization were unlikely to show subsequent improvement in PVRi (1/8, 13%). These findings may help clinicians counsel families and guide clinical decision making regarding the timing of advanced therapies.

Current practices for refractory chylothorax following congenital heart surgery.

INTRODUCTION: Chylothorax following paediatric cardiac surgery is associated with significant morbidity, particularly those that are refractory to conservative therapy. It is our impression that there is important variability in the medical, surgical, and interventional therapies used to manage refractory chylothorax between congenital heart programmes. We therefore conducted a survey study of current practices for managing refractory chylothorax. METHODS: The Chylothorax Work Group, formed with the support of the Pediatric Cardiac Critical Care Consortium, designed this multi-centre survey study with a focus on the timing and indication for utilising known therapies for refractory chylothorax. The survey was sent to one chylothorax expert from each Work Group centre, and results were summarised and reported as the frequency of given responses. RESULTS: Of the 20 centres invited to participate, 17 (85%) submitted complete responses. Octreotide (13/17, 76%) and sildenafil (8/17, 47%) were the most utilised medications. Presently, 9 (53%) centres perform pleurodesis, 15 (88%) perform surgical thoracic duct ligation, 8 (47%) perform percutaneous lymphatic interventions, 6 (35%) utilise thoracic duct decompression procedures, and 3 (18%) perform pleuroperitoneal shunts. Diagnostic lymphatic imaging is performed prior to surgical thoracic duct ligation in only 7 of the 15 (47%) centres that perform the procedure. Respondents identified barriers to referring and transporting patients to centres with expertise in lymphatic interventions. CONCLUSIONS: There is variability in the treatment of refractory post-operative chylothorax across a large group of academic heart centres. Few surveyed heart centres have replaced surgical thoracic duct ligation or pleurodesis with image-guided selective lymphatic interventions.

Acute Hemodynamics in the Fontan Circulation: Open-Label Study of Vasopressin.

OBJECTIVE: To describe the acute hemodynamic effect of vasopressin on the Fontan circulation, including systemic and pulmonary pressures and resistances, left atrial pressure, and cardiac index. DESIGN: Prospective, open-label, nonrandomized study (NCT04463394). SETTING: Cardiac catheterization laboratory at Lucile Packard Children's Hospital, Stanford. PATIENTS: Patients 3-50 years old with a Fontan circulation who were referred to the cardiac catheterization laboratory for hemodynamic assessment and/or intervention. INTERVENTIONS: A 0.03 U/kg IV (maximum dose 1 unit) bolus of vasopressin was administered over 5 minutes, followed by a maintenance infusion of 0.3 mU/kg/min (maximum dose 0.03 U/min). MEASUREMENTS AND MAIN RESULTS: Comprehensive cardiac catheterization measurements before and after vasopressin administration. Measurements included pulmonary artery, atrial, and systemic arterial pressures, oxygen saturations, and systemic and pulmonary flows and resistances. There were 28 patients studied. Median age was 13.5 (9.1, 17) years, and 16 (57%) patients had a single or dominant right ventricle. Following vasopressin administration, systolic blood pressure and systemic vascular resistance (SVR) increased by 17.5 (13.0, 22.8) mm Hg ( Z value -4.6, p < 0.001) and 3.8 (1.8, 7.5) Wood Units ( Z value -4.6, p < 0.001), respectively. The pulmonary vascular resistance (PVR) decreased by 0.4 ± 0.4 WU ( t statistic 6.2, p < 0.001), and the left atrial pressure increased by 1.0 (0.0, 2.0) mm Hg ( Z value -3.5, p < 0.001). The PVR:SVR decreased by 0.04 ± 0.03 ( t statistic 8.1, p < 0.001). Neither the pulmonary artery pressure (median difference 0.0 [-1.0, 1.0], Z value -0.4, p = 0.69) nor cardiac index (0.1 ± 0.3, t statistic -1.4, p = 0.18) changed significantly. There were no adverse events. CONCLUSIONS: In Fontan patients undergoing cardiac catheterization, vasopressin administration resulted in a significant increase in systolic blood pressure, SVR, and left atrial pressure, decrease in PVR, and no change in cardiac index or pulmonary artery pressure. These findings suggest that in Fontan patients vasopressin may be an option for treating systemic hypotension during sedation or general anesthesia.

Prediction Model with External Validation for Early Detection of Postoperative Pediatric Chylothorax.

Earlier diagnosis of chylothorax following pediatric cardiac surgery is associated with decreased duration of chylothorax. Pleural fluid testing is used to diagnosis chylothorax which may delay detection in patients who are not enterally fed at time of chylothorax onset. Our aim was to develop and externally validate a prediction model to detect chylothorax earlier than pleural fluid testing in pediatric patients following cardiac surgery. A multivariable logistic regression model was developed to detect chylothorax using a stepwise approach. The model was developed using data from patients < 18 years following cardiac surgery from Primary Children's Hospital, a tertiary-care academic center, between 2017 and 2020. External validation used a contemporary cohort (n = 171) from Lucille Packard Children's Hospital. A total of 763 encounters (735 patients) were analyzed, of which 72 had chylothorax. The final variables selected were chest tube output (CTO) the day after sternal closure (dichotomized at 15.6 mL/kg/day, and as a continuous variable) and delayed sternal closure. The highest odds of chylothorax were associated with CTO on post-sternal closure day 1 > 15.6 mL/kg/day (odds ratio 11.3, 95% CI 6,3, 21.3). The c-statistic for the internal and external validation datasets using the dichotomized CTO variable were 0.78 (95% CI 0.73, 0.82) and 0.84 (95% CI, 0.78, 0.9) and performance improved when using CTO as a continuous variable (OR 0.84, CI: 95% CI 0.80, 0.87). Using the models described, chylothorax after pediatric cardiac surgery may be detected earlier and without reliance on enteral feeds.

Role of left atrial hypertension in pulmonary hypertension associated with bronchopulmonary dysplasia.

Left atrial hypertension (LAH) may contribute to pulmonary hypertension (PH) in premature infants with bronchopulmonary dysplasia (BPD). Primary causes of LAH in infants with BPD include left ventricular diastolic dysfunction or hemodynamically significant left to right shunt. The incidence of LAH, which is definitively diagnosed by cardiac catheterization, and its contribution to PH is unknown in patients with BPD-PH. We report the prevalence of LAH in an institutional cohort with BPD-PH with careful examination of hemodynamic contributors and impact on patient outcomes. This single-center, retrospective cohort study examined children <2 years of age with BPD-PH who underwent cardiac catheterization at Lucile Packard Children's Hospital Stanford. Patients with unrepaired simple shunt congenital heart disease (CHD) and pulmonary vein stenosis (only 1 or 2 vessel disease) were included. Patients with complex CHD were excluded. From April 2010 to December 2021, 34 patients with BPD-PH underwent cardiac catheterization. We define LAH as pulmonary capillary wedge pressure (PCWP) or left atrial pressure (LAP) of at least 10 mmHg. In this cohort, median PCWP was 8 mmHg, with LAH present in 32% (n = 11) of the total cohort. A majority (88%, n = 30) of the cohort had severe BPD. Most patients had some form of underlying CHD and/or pulmonary vein stenosis: 62% (n = 21) with an atrial septal defect or patent foramen ovale, 62% (n = 21) with patent ductus arteriosus, 12% (n = 4) with ventricular septal defect, and 12% (n = 4) with pulmonary vein stenosis. Using an unadjusted logistic regression model, baseline requirement for positive pressure ventilation at time of cardiac catheterization was associated with increased risk for LAH (odds ratio 8.44, 95% CI 1.46-48.85, p = 0.02). Small for gestational age birthweight, sildenafil use, and CHD were not associated with increased risk for LAH. LAH was associated with increased risk for the composite outcome of tracheostomy and/or death, with a hazard ratio of 6.32 (95% CI 1.72, 22.96; p = 0.005). While the etiology of BPD-PH is multifactorial, LAH is associated with PH in some cases and may play a role in clinical management and patient outcomes.

Virtual Transcatheter Interventions for Peripheral Pulmonary Artery Stenosis in Williams and Alagille Syndromes.

Background Despite favorable outcomes of surgical pulmonary artery (PA) reconstruction, isolated proximal stenting of the central PAs is common clinical practice for patients with peripheral PA stenosis in association with Williams and Alagille syndromes. Given the technical challenges of PA reconstruction and the morbidities associated with transcatheter interventions, the hemodynamic consequences of all treatment strategies must be rigorously assessed. Our study aims to model, assess, and predict hemodynamic outcomes of transcatheter interventions in these patients. Methods and Results Isolated proximal and "extensive" interventions (stenting and/or balloon angioplasty of proximal and lobar vessels) were performed in silico on 6 patient-specific PA models. Autoregulatory adaptation of the cardiac output and downstream arterial resistance was modeled in response to intervention-induced hemodynamic perturbations. Postintervention computational fluid dynamics predictions were validated in 2 stented patients and quantitatively assessed in 4 surgical patients. Our computational methods accurately predicted postinterventional PA pressures, the primary indicators of success for treatment of peripheral PA stenosis. Proximal and extensive treatment achieved median reductions of 14% and 40% in main PA systolic pressure, 27% and 56% in pulmonary vascular resistance, and 10% and 45% in right ventricular stroke work, respectively. Conclusions In patients with Williams and Alagille syndromes, extensive transcatheter intervention is required to sufficiently reduce PA pressures and right ventricular stroke work. Transcatheter therapy was shown to be ineffective for long-segment stenosis and pales hemodynamically in comparison with published outcomes of surgical reconstruction. Regardless of the chosen strategy, a virtual treatment planning platform could identify lesions most critical for optimizing right ventricular afterload.

Comprehensive diagnostic catheterization in children with major aortopulmonary collateral arteries: A review of catheterization technique and anatomic nomenclature.

Achieving an optimal surgical result in patients with major aortopulmonary collateral arteries (MAPCAs) requires a thorough preoperative evaluation of the anatomy and physiology of the pulmonary circulation. This review provides a detailed description of diagnostic catheterization in patients with MAPCAs, including a summary of catheterization techniques, an overview of commonly used terms, and a review of MAPCA and pulmonary artery angiographic anatomy.

Balloon Angioplasty for Pulmonary Artery Stenosis After Complete Unifocalization and Repair of Tetralogy of Fallot With Major Aortopulmonary Collaterals.

OBJECTIVES: The objective of this study was to assess procedural outcomes of balloon pulmonary artery (PA) angioplasty procedures after complete repair of tetralogy of Fallot with major aortopulmonary collateral arteries (TOF/MAPCAs). BACKGROUND: Our approach to patients with TOF/MAPCAs emphasizes early complete unifocalization and repair. Major PA reinterventions are relatively uncommon. Balloon PA angioplasty is often used, but the effectiveness of balloon PA angioplasty in this population is unknown. METHODS: The study cohort comprised patients who underwent complete unifocalization and repair of TOF/ MAPCAs at our center between 2002-2018 and underwent balloon PA angioplasty after repair. To assess immediate procedural outcomes, pre- and postintervention PA measurements were compared. RESULTS: We reviewed 134 vessels that were dilated a median of 1.1 years after repair in 60 patients (median 2 PA branches per patient). Treated vessels included 15 central, 64 lobar, and 55 segmental branches. The median PA diameter at the level of stenosis increased from 1.9 mm to 3.3 mm (P<.001), and the median diameter increase was 50%. All but 6 treated vessels were enlarged. The stenosis-distal diameter ratio increased from a median of 64% to 89% (P<.001). The median central PA to aortic systolic pressure ratio was 47% before and 39% after intervention (P<.001). CONCLUSIONS: Balloon PA angioplasty was acutely effective at treating most stenoses of reconstructed PA branches after repair of TOF/MAPCAs. Simple angioplasty can be a useful tool in treating isolated or modest stenoses after unifocalization/PA reconstruction surgery using our approach.

Unilateral Branch Pulmonary Artery Origin From a Solitary Arterial Trunk With Major Aortopulmonary Collaterals to the Contralateral Lung: Anatomic and Developmental Considerations.

In both truncus arteriosus communis (TAC) and tetralogy of Fallot (TOF), there is a rare phenotype that includes a single branch pulmonary artery (PA) arising from a solitary great artery and major aortopulmonary collaterals (MAPCAs) supplying the contralateral lung. We describe the intracardiac and great vessel anatomy of infants with this phenotype, consider rationale for classifying patients as TOF vs TAC, and describe surgical outcomes. Our institution's surgical database was reviewed for patients with a single branch PA from a solitary arterial trunk and contralateral MAPCAs from 2007 to 2019. Demographic, imaging, and surgical data were collected and described. All 11 patients underwent complete repair with a median right ventricular to aortic pressure ratio of 0.36 (range 0.26-0.50). At 0.1-9.1 years after repair (median 0.8 years) there was approximately balanced left-right lung perfusion (median 52% to the right lung, range 34-74%). The MAPCA lungs exemplified the full spectrum of PA and MAPCA anatomy, from absent intrapericardial PAs with all single supply MAPCAs to a normally arborizing PA with all dual supply MAPCAs and present pulmonary valve leaflet tissue. All patients had a systemic semilunar valve with 3 thin and similarly sized leaflets and fibrous continuity with the tricuspid valve, and all had coronary origins and outflow tract morphology more consistent with TOF. It is appropriate to classify all patients with a single anomalous PA from a solitary arterial trunk and MAPCAs to the contralateral lung as TOF rather than TAC Type A3. All variants were amenable to surgical repair.

Angiographic Anatomy of Major Aortopulmonary Collateral Arteries and Association With Early Surgical Outcomes in Tetralogy of Fallot.

Background Due in part to the heterogeneity of the pulmonary circulation in patients with tetralogy of Fallot and major aortopulmonary collateral arteries (MAPCAs), research on this condition has focused on relatively basic anatomic characteristics. We aimed to detail pulmonary artery (PA) and MAPCA anatomy in a large group of infants, assess relationships between anatomy and early surgical outcomes, and consider systems for classifying MAPCAs. Methods and Results All infants ( <1 year of age) undergoing first cardiac surgery for tetralogy of Fallot/MAPCAs from 2001 to 2019 at Stanford University were identified. Preoperative angiograms delineating supply to all 18 pulmonary segments were reviewed for details of each MAPCA and the arborization and size of central PAs. We studied 276 patients with 1068 MAPCAs and the following PA patterns: 152 (55%) incompletely arborizing PAs, 48 (17%) normally arborizing PAs, 45 (16%) absent PAs, and 31 (11%) unilateral MAPCAs. There was extensive anatomic variability, but no difference in early outcomes according to PA arborization or the predominance of PAs or MAPCAs. Patients with low total MAPCA and/or PA cross-sectional area were less likely to undergo complete repair. Conclusions MAPCA anatomy is highly variable and essentially unique for each patient. Though each pulmonary segment can be supplied by a MAPCA, central PA, or both, all anatomic combinations are similarly conducive to a good repair. Total cross-sectional area of central PA and MAPCA material is an important driver of outcome. We elucidate a number of novel associations between anatomic features, but the extreme variability of the pulmonary circulation makes a granular tetralogy of Fallot/MAPCA classification system unrealistic.

Pulmonary hemorrhage in children with Alagille syndrome undergoing cardiac catheterization.

OBJECTIVES: To evaluate the incidence, severity, and outcomes of pulmonary hemorrhage in children with Alagille syndrome (AGS) undergoing cardiac catheterization, and to find variables associated with hemorrhage in this population. BACKGROUND: Children with AGS have a high incidence of bleeding complications during invasive procedures. It has been our impression that catheterization-associated pulmonary hemorrhage is more common in children with AGS, but there are no published data on this topic. METHODS: This was a retrospective single institution study of children with AGS undergoing catheterization from 2010 to 2018. Pulmonary hemorrhage was defined as angiographic or fluoroscopic evidence of extravasated blood in the lung parenchyma, or blood suctioned from the endotracheal tube with documentation of pulmonary hemorrhage by the anesthesiologist or intensivist. Univariate comparisons were made between catheterizations that did and did not have pulmonary hemorrhage. RESULTS: Thirty children with AGS underwent 87 catheterizations, 32 (37%) with interventions on the branch pulmonary arteries (PA). There were 26 (30%) procedures with hemorrhage, the majority (65%) of which were self-limited or required less than 24 hr of mechanical ventilation. Moderate and severe hemorrhage occurred only in children with tetralogy of Fallot (TOF; 5 of 14, 36%). A higher right ventricle to aorta systolic pressure ratio (1.0 [0.85-1.1] vs. 0.88 [0.59-1.0], p = .029) and interventions on the branch PAs (14 of 26, 54% vs. 18 of 61, 30%, p = .032) were associated with hemorrhage. CONCLUSIONS: Pulmonary hemorrhage was common in children with AGS undergoing both intervention and diagnostic cardiac catheterization, and was associated with TOF, higher RV to aorta pressure ratio, and interventions on the branch PAs.

Secondary repair of incompetent pulmonary valves after previous surgery or intervention: Patient selection and outcomes.

OBJECTIVES: Pulmonary valve (PV) regurgitation (PR) is common after intervention for a hypoplastic right ventricular outflow tract. Secondary PV repair is an alternative to replacement (PVR), but selection criteria are not established. We sought to elucidate preoperative variables associated with successful PV repair and to compare outcomes between repair and PVR. METHODS: Patients who underwent surgery for secondary PR from 2010 to 2017 by a single surgeon were studied. The PV annulus and leaflets were measured on the preoperative echocardiogram and magnetic resonance images, and the primary predictor variable was leaflet area indexed to ideal PV annulus area (iPLA) by magnetic resonance imaging. PV repair and PVR groups were compared using multivariable logistic regression, and with a conditional inference tree. Freedom from PV dysfunction and from reintervention were assessed with Kaplan-Meier survival analyses. RESULTS: Of 85 patients, 31 (36%) underwent PV repair. By multivariable analysis, longer PV total leaflet length (cm/m2) (ß = 3.00, standard error [SE] = 0.82, P < .001), larger PV z score (ß = 1.34, SE = 0.39, P = .001), and larger iPLA (ß = 8.13, SE = 2.62, P = .002) were associated with repair. iPLA of 0.90 or greater was 91% sensitive and 83% specific for achieving PV repair. At a median of 4.1 years follow-up, there was greater freedom from significant PR in the PV repair group (log rank P = .008). CONCLUSIONS: Patients with an iPLA >0.9, and those with an iPLA between 0.7 and 0.9 with a PV annulus z score >0 should be considered for a native PV repair. At midterm follow-up, patients with a PV repair were not more likely to develop PR or to require reintervention when compared with patients undergoing PVR.

Postoperative Recovery of Left Ventricular Function following Repair of Large Ventricular Septal Defects in Infants.

INTRODUCTION: Early postoperative left ventricular (LV) dysfunction is observed following repair of large ventricular septal defects (VSDs), but the frequency and rate of recovery of LV function are unknown. This study aims to characterize the incidence and rate of recovery of postoperative LV dysfunction following repair of large VSDs and to improve understanding of LV mechanics before and after VSD repair. METHODS: Infants who underwent surgical repair of an isolated large VSD were included. Pre- and postoperative echocardiographic images were reviewed, and LV function was assessed by both conventional echocardiography and speckle-tracking strain analyses. Postoperative LV dysfunction was defined as an LV ejection fraction (LVEF) < 50% using the 5/6 area-length method. Echocardiograms were reviewed to assess LVEF and LV volume through 1-year follow-up. RESULTS: Of 104 infants evaluated (median age, 0.31 [0.22, 0.56] years), all had normal preoperative LVEF and 39 (38%) had postoperative LV dysfunction. Follow-up echocardiograms were available in 31 (80%) patients, all of whom had LVEF > 50% within 9 months of surgery. Lower preoperative apical four-chamber longitudinal strain (A4LS) and greater LV end-diastolic volume indexed to body surface area1.38 were independently associated with postoperative LV dysfunction. An absolute preoperative A4LS < 16.7% (area under the curve = 0.87; 95% CI, 0.78-0.95; P < .001) was most strongly associated with postoperative dysfunction. CONCLUSIONS: Infants with LV dysfunction following repair of large VSDs recover function within 9 months. Preoperative A4LS can be helpful to detect subclinical LV dysfunction in the setting of a large hemodynamically significant VSD and guide postoperative expectations for providers and families.

Subcutaneous and Intravenous Treprostinil Pharmacokinetics in Children With Pulmonary Vascular Disease.

This study evaluated the pharmacokinetics of intravenous (IV) and subcutaneous (SC) treprostinil in pediatric patients with pulmonary vascular disease, and compared them with existing adult data from a similar cohort. Blood samples were collected from pediatric patients receiving steady-state IV or SC treprostinil and were assessed for plasma treprostinil concentration using liquid chromatography and tandem mass spectrometry. Forty participants, 15 receiving IV and 25 receiving SC treprostinil, were included in the analysis. Age ranged from 0.1 to 15.6 years. The median dose of treprostinil was 45.5 ng·kg·min with a range of 8-146 ng·kg·min. There was a linear relationship between treprostinil dose and plasma concentration with an R of 0.57. On average, there were higher blood concentrations per given dose of IV treprostinil compared with those per given dose of SC, but the difference was not significant. Compared with adult data, the slope of the pediatric data was similar, but the y-intercept was significantly lower. Additionally, the concentration per dose ratio was significantly higher in adults compared with children. Pediatric patients have significantly lower average blood concentrations of treprostinil per given dose compared with adults, and higher, but not significantly so, blood concentrations when treprostinil is administered IV as compared with SC administration.

Transcatheter redirection of hepatic venous blood to treat unilateral pulmonary arteriovenous malformations in a Fontan circulation by short-term total exclusion of the unaffected lung.

Clinically significant unilateral pulmonary arteriovenous malformations (PAVM) can develop in patients with a Fontan circulation when there is unbalanced distribution of hepatic venous (HV) blood flow to the lungs. There are reported surgical and transcatheter techniques to treat PAVMs by rerouting HV return, with promising short-term results. We report a case of a novel, technically simple transcatheter approach to redirect HV blood flow in an adult Fontan patient with polysplenia syndrome and severe unilateral PAVMs. Our patient had a two-stage procedure, the first to redirect all HV blood flow to the affected lung with a single covered stent, and a second to confirm resolution of PAVMs and to reintroduce HV effluent to the unaffected lung. At 10-month follow-up, her oxygen saturations had increased from 75% to 93% with a marked improvement in her functional status.

Text4Peds: Feasibility of an Educational Text-Messaging Program for Pediatrics Residents.

BACKGROUND: There is an ongoing effort to maximize educational material provided to residents who are in a time-constrained work environment. Mobile technology, principally smartphone applications and online modules, has shown educational promise. INTERVENTION: We developed a text-messaging program, Text4Peds, to assist residents with preparation for their pediatric board examinations. Goals were to assess (1) the feasibility of texting educational messages to residents, and (2) resident satisfaction and perceived usefulness of a texting program. METHODS: We conducted a prospective study of pediatrics and combined internal medicine-pediatrics residents. Messages derived from the most missed pediatric in-training examination questions were sent daily to residents. After 3 months, residents completed surveys that gauged their perception on the educational value of the text messages and the effect on their pediatric board preparation. Feasibility of the system was assessed as a total percentage of messages successfully received by residents. RESULTS: Of 55 residents, 35 (64%) participated in the program. Of 2534 messages sent out to participants, 2437 (96.2%) were delivered successfully. Positive comments cited the texting of board facts as a quick, helpful, daily study tool. Residents liked that messages were sent at 2:00 pm, and most felt that 1 to 5 messages per week was appropriate. Drawbacks included character restrictions of messages, content limitations, and the lack of a question-answer format. CONCLUSIONS: An educational text message-based program was successfully implemented in our residency program. Messages were delivered with a high success rate, and residents found educational value in the messages.