A North American, single-center experience implanting fenestrated atrial devices and atrial flow regulators into a heterogeneous group of pediatric pulmonary hypertension patients.

Introduction: The clinical deterioration commonly experienced by pediatric patients with pulmonary arterial hypertension (PAH) has motivated a shift in the treatment of pulmonary hypertension (PH) through innovations in surgical salvage interventions. The Occlutech fenestrated atrial septal defect (FASD) Occluder and the atrial flow regulator (AFR), which provides a protective, atrial-level shunt during hypertensive crises, have found an important role in treating pediatric patients with PAH. Other groups of pediatric patients with PH may also benefit from a similar protective physiology. The primary aim of this work is to present a single center's experience with AFR and FASD devices for managing a heterogeneous group of pediatric PH patients. A secondary goal is to identify hemodynamic changes and complications following device implantation. Materials and Methods: We performed a retrospective review of all pediatric PH patients who, after being found suitable, either successfully or unsuccessfully received an FASD or AFR device between January 2015 and December 2021 at the Stollery Children's Hospital in Edmonton, Canada. Results: Fourteen patients (eight female) with a median age of 4.6 (range 0.3-17.9) years and a median body mass index of 15.1 (Q1 = 13.8, Q3 = 16.8) kg/m2 underwent device implantation: five received FASDs, eight received AFRs, and one was ultimately unable to receive an implant due to thrombosed iliac vessels and required surgical intervention. Of the fourteen patients, seven were in group 1 (PAH), one was in group 3 (lung disease), and six were in group 5 (primarily pulmonary hypertension vascular disease) under the World Symposium PH classification. All patients were on mono-, dual-, or triple-drug PH therapy. Device stabilization was not possible for two patients, who then required a repeat catheterization. Of the group 1 patients, three AFR and three FASD implants were successful, while one FASD implant was unsuccessful due to thrombosed vessels. At a six-month clinical assessment, all group 1 patients had patent devices and improved WHO FCs. Conclusion: This work presents a single center's experience with AFR and FASD implants in a heterogeneous group of fourteen pediatric patients with severe PH. This treatment strategy is novel in the pediatric population and so this work provides momentum for future studies of interventional cardiac catheterization procedures for pediatric patients with PH. Further collaborations are required to develop criteria to identify ideal pediatric candidates and optimally time interventions in order to maximize the benefits of this treatment.

Percutaneous Treatment of Ascending Aortic Obstruction in a Young Child After Orthotopic Heart Transplantation.

We report a case of a 14-month-old child with ascending aortic obstruction (AAO) post cardiac transplantation, who underwent successful percutaneous ascending aortic stent angioplasty. Congenital or acquired AAO is typically treated with surgical augmentation. The experience with percutaneous techniques is limited and often avoided due to challenges with equipment stability and proximity to coronary arteries and aortic valve leaflets. This case highlights that a percutaneous approach to relief of AAO is a feasible alternative even in small children utilizing a newer pre-mounted stent.

Practice Patterns in the Management of Pressure Restrictive Perimembranous Ventricular Septal Defects: A Multinational Survey.

Indications for the closure of pressure restrictive perimembranous ventricular septal defects (pmVSD) are not well established in the pediatric population. We sought to assess practice variability among pediatric cardiologists in the United States (US), Canada, Australia, and New Zealand. A survey ascertaining practice patterns, including case vignettes with incremental progression of disease severity, was designed and administered through representative professional cardiac organizations and email listservs in the designated countries. Among the 299 respondents, 209 (70.0%) were from the US, 65 (21.7%) were from Canada and 25 (8.3%) were from Australia and New Zealand. Indications for pressure restrictive pmVSD closure included the presence of left ventricular (LV) dilation for 81.6% (244/299) (defined as z-score ≥ 2 for 59.0% (144/244) and ≥ 3 for 40.2% (98/244)) and significant pulmonary-systemic flow ratio (QP:QS) for 71.2% (213/299) [defined as ≥ 1.5:1 for 36.2% (77/213) and ≥ 2 for 62% (132/213)]. US pediatric cardiologists elected to close restrictive pmVSD at lower LV z-score and QP:QS ratio cut-offs (p-value 0.0002 and 0.013, respectively). In a case vignette, 63.6% (173/272) chose to intervene if there was right coronary cusp prolapse with stable mild aortic regurgitation. Of the remaining cardiologists, 93% (92/99) intervened if the aortic regurgitation was progressive (from trivial to mild). Commonly identified indications with variable thresholds for closure of pressure restrictive pmVSDs included the presence or progression of LV dilation, significant volume loading, and aortic valve prolapse with regurgitation. US pediatric cardiologists may have a lower threshold for pmVSD closure.

Implantation of atrial flow regulator devices in patients with congenital heart disease and children with severe pulmonary hypertension or cardiomyopathy-an international multicenter case series.

Background: The Occlutech Atrial Flow Regulator (AFR) is a self-expandable double-disc nitinol device with a central fenestration. Its use has been approved in the adult population with heart failure and described for pulmonary hypertension (PH). Only case reports and small series have been published about its use in the paediatric population and for congenital heart disease (CHD). Objectives: The authors sought to investigate the feasibility, safety, and short-term follow-up of AFR implantation in patients with CHD or children with PH or cardiomyopathy. Methods: This is a multicenter retrospective study involving 10 centers worldwide. Patients of any age with CHD or patients aged < 18 years with PH or cardiomyopathy needing AFR implantation were included. Results: A total of 40 patients underwent AFR implantation. The median age of the population at the time of the procedure was 58.5 months (IQR: 31.5-142.5) and the median weight was 17 kg (IQR: 10-46). A total of 26 (65.0%) patients had CHD, nine (22.5%) children, a cardiomyopathy, and five (12.5%), a structurally normal heart. The implantation success rate was 100%. There were two early and one late device thrombosis. Two patients (5.0%) with dilated cardiomyopathy on extracorporeal membrane oxygenator (ECMO) died during the hospital stay. At a median follow-up of 330 days (IQR: 125-593), 37 (92.5%) patients were alive. At follow-up, 20 patients improved their New York Heart Association (NYHA) class, 12 patients did not change their NYHA class, and one patient with idiopathic PH worsened. Conclusions: AFR implantation in patients with CHD and children with severe PH or cardiomyopathy is promising and seems to have beneficial effects at short-term follow-up.

Augmentation of Pulmonary Arterial Growth in Single Ventricle Patients by Interim Selective Shunts.

Stenosis or diffuse hypoplasia of central pulmonary arteries (PA) is common in patients with single ventricle physiology, often requiring surgical patching. Such repairs are prone to failure, particularly with low pressure venous flow (bidirectional cavopulmonary connection or Fontan). We describe our experience of disconnection of central PA and selective systemic-PA shunt to the hypoplastic vessel. Single ventricle patients (n = 12) with diffuse left pulmonary artery (LPA) hypoplasia (LPA:right pulmonary artery diameter <0.7) underwent PA disconnection (ligation clip) and selective arterial shunt to the LPA. Patients with ≤mild atrioventricular valve regurgitation, and no more than mild systolic dysfunction on echocardiogram were considered. Following systemic-LPA shunt, patients were reassessed by cardiac catheterization prior to further surgery, with follow-up catheterization later performed and description of changes observed. Increased volume loading was well tolerated with no greater than mild atrioventricular valve regurgitation and preserved systolic function (normal or mildly reduced). Selective arterial shunting increased the caliber of the LPA from 4.1 mm (1.2-5.6) to 6.5 mm (1.7-11.9) and this increase was preserved post-Fontan (6.7 mm [1.3-8.0]) (median [range]). Ventricular end diastolic pressure increased with arterial shunting but resolved after shunt takedown and Fontan completion (median +3 and -4 mm Hg respectively). Post-Fontan hospital length of stay was not prolonged (median 11 days, range 7-14). No deaths occurred. In univentricular hearts and PA hypoplasia, selective systemic-PA shunting physiologically increases the caliber of the distal vessels. In selected patients this can be done safely with maintenance of PA growth and resolution of the elevated end diastolic pressure with Fontan completion.

Acute and medium term results of balloon expandable stent placement in the transverse arch-a multicenter pediatric interventional cardiology early career society study.

OBJECTIVES AND BACKGROUND: Coarctation of the aorta represents 5-8% of all congenital heart disease. Although balloon expandable stents provide an established treatment option for native or recurrent coarctation, outcomes from transverse arch (TAO) stenting, including resolution of hypertension have not been well studied. This study aims to evaluate immediate and midterm results of TAO stenting in a multi-center retrospective cohort. METHODS: TAO stenting was defined as stent placement traversing any head and neck vessel, with the primary intention of treating narrowing in the transverse aorta. Procedural details, complications and medications were assessed immediately post procedure, at 6 month follow-up and at most recent follow-up. RESULTS: Fifty-seven subjects, 12 (21%) native, and 45 (79%) surgically repaired aortic arches, from seven centers were included. Median age was 14 years (4 days-42 years), median weight 54 kg (1.1-141 kg). After intervention, the median directly measured arch gradient decreased from 20 mmHg (0-57 mmHg) to 0 mmHg (0-23 mmHg) (p < .001). The narrowest arch diameter increased from 9 mm (1.4-16 mm) to 14 mm (2.9-25 mm) (p < .001), with a median increase of 4.9 mm (1.1-10.1 mm). One or more arch branches were covered by the stent in 55 patients (96%). There were no serious adverse events. Two patients warranted stent repositioning following migration during deployment. There were no late complications. There were 8 reinterventions, 7 planned, and 1 unplanned (6 catheterizations, 2 surgeries). Antihypertensive management was continued in 19 (40%) at a median follow-up of 3.2 years (0.4-7.3 years). CONCLUSIONS: TAO stenting can be useful in selected patients for resolution of stenosis with minimal complications. This subset of patients are likely to continue on antihypertensive medications despite resolution of stenosis.

Intra-pulmonary arteriovenous anastomoses and pulmonary gas exchange: evaluation by microspheres, contrast echocardiography and inert gas elimination.

KEY POINTS: Imaging techniques such as contrast echocardiography suggest that anatomical intra-pulmonary arteriovenous anastomoses (IPAVAs) are present at rest and are recruited to a greater extent in conditions such as exercise. IPAVAs have the potential to act as a shunt, although gas exchange methods have not demonstrated significant shunt in the normal lung. To evaluate this discrepancy, we compared anatomical shunt with 25-µm microspheres to contrast echocardiography, and gas exchange shunt measured by the multiple inert gas elimination technique (MIGET). Intra-pulmonary shunt measured by 25-µm microspheres was not significantly different from gas exchange shunt determined by MIGET, suggesting that MIGET does not underestimate the gas exchange consequences of anatomical shunt. A positive agitated saline contrast echocardiography score was associated with anatomical shunt measured by microspheres. Agitated saline contrast echocardiography had high sensitivity but low specificity to detect a ≥1% anatomical shunt, frequently detecting small shunts inconsequential for gas exchange. ABSTRACT: The echocardiographic visualization of transpulmonary agitated saline microbubbles suggests that anatomical intra-pulmonary arteriovenous anastomoses are recruited during exercise, in hypoxia, and when cardiac output is increased pharmacologically. However, the multiple inert gas elimination technique (MIGET) shows insignificant right-to-left gas exchange shunt in normal humans and canines. To evaluate this discrepancy, we measured anatomical shunt with 25-µm microspheres and compared the results to contrast echocardiography and MIGET-determined gas exchange shunt in nine anaesthetized, ventilated canines. Data were acquired under the following conditions: (1) at baseline, (2) 2 µg kg-1  min-1 i.v. dopamine, (3) 10 µg kg-1  min-1 i.v. dobutamine, and (4) following creation of an intra-atrial shunt (in four animals). Right to left anatomical shunt was quantified by the number of 25-µm microspheres recovered in systemic arterial blood. Ventilation-perfusion mismatch and gas exchange shunt were quantified by MIGET and cardiac output by direct Fick. Left ventricular contrast scores were assessed by agitated saline bubble counts, and separately by appearance of 25-µm microspheres. Across all conditions, anatomical shunt measured by 25-µm microspheres was not different from gas exchange shunt measured by MIGET (microspheres: 2.3 ± 7.4%; MIGET: 2.6 ± 6.1%, P = 0.64). Saline contrast bubble score was associated with microsphere shunt (ρ = 0.60, P < 0.001). Agitated saline contrast score had high sensitivity (100%) to detect a ≥1% shunt, but low specificity (22-48%). Gas exchange shunt by MIGET does not underestimate anatomical shunt measured using 25-µm microspheres. Contrast echocardiography is extremely sensitive, but not specific, often detecting small anatomical shunts which are inconsequential for gas exchange.

An Unusual Cause of Hemopericardium 22 Years After a Fontan Procedure.

Late tamponade after cardiac operations is rare but reasonably well described. We report a case of exceedingly late tamponade secondary to a spontaneous coronary bleed 22 years after a Fontan operation, which was repaired with catheter intervention.

Long-term results of a strategy of aortic valve repair in the pediatric population.

OBJECTIVES: To determine rate of reoperation subsequent to primary valve repair in a pediatric population. METHODS: Between 1996 and 2009, 142 consecutive patients underwent aortic valve repair in our institution. Median age at surgery was 9 years, with 30 being younger than age 1 year. Indication for surgery was stenosis (n = 76), regurgitation (n = 55), and both (n = 11). Forty-six patients underwent repair with no addition of patch, whereas 96 patients required addition of patches of glutaraldehyde preserved autologous pericardium for cusp extension (n = 51) and other repair (n = 45). RESULTS: In the early postoperative period after cusp extension repair, 2 patients had a sudden unexplained death and 1 had cardiac arrest requiring mechanical support and heart transplantation. Two additional patients with cusp extension displayed signs of coronary ischemia. After a mean follow-up of 3.4 ± 3.5 years, only 1 patient died of a noncardiac cause. Seven-year freedom from reoperation was 80% (95% confidence interval [CI], 66-89). By multivariate analysis, the only predictors of reintervention were cusp extension (hazard ratio [HR], 5.4; 95% CI, 1.7-16.8; P = .004) and infants (HR, 5.6; 95% CI, 1.7-18.4; P = .005). At final echocardiography follow-up, 23 of 119 survivors without reoperation had moderate (19%), 1 had moderate-severe (1%), and 1 had severe regurgitation (1%), whereas 12 (10%) had a moderate degree of stenosis. CONCLUSIONS: Aortic valve repair in pediatric populations is effective in postponing reintervention. The longevity of the repair is shorter after cusp extension and when performed in infants. Caution should be used when performing tricsupidization and cusp extension of bicuspid valves because it can be responsible for mortality related to occlusion of the coronary ostia by patches.

High-concentration nitrous oxide for procedural sedation in children: adverse events and depth of sedation.

OBJECTIVE: Nitrous oxide is an attractive agent for procedural sedation and analgesia in the emergency department; however, there are limited safety data for high-concentration continuous-flow nitrous oxide (50%-70%) and its use in young children. We set out to characterize the depth of sedation and incidence of adverse events associated with various concentrations of nitrous oxide used in a pediatric emergency department. METHODS: This was a prospective observational study of nitrous oxide use for procedural sedation and analgesia in a tertiary children's hospital emergency department. Nitrous oxide concentration, adverse events, and sedation depth were recorded. Adverse events were categorized as mild or serious. Sedation depth was recorded on a sedation scale from 0 to 6. RESULTS: A total of 762 patients who were aged 1 to 17 years received nitrous oxide during the 2-year study period. A total of 548 (72%) received nitrous oxide 70%, and 101 (13%) received nitrous oxide 50%. Moderate or deep sedation with scores of < or = 2 occurred in 3% of patients who had received nitrous oxide 70% and no patients who had received nitrous oxide 50%. Mean sedation scores were 4.4 at nitrous oxide 70% and 4.6 at nitrous oxide 50%. Sixty-three (8.3%) patients sustained 70 mild and self-resolving adverse events, most of which were vomiting (5.7%); 2 (0.2%) patients had serious adverse events. There was no significant difference in adverse events rates between nitrous oxide 70% (8.4%) and nitrous oxide 50% (9.9%). There was no significant difference in the percentage of deep sedation when children who were < or = 3 years of age (2.9%) were compared with older children (2.8%). CONCLUSIONS: In this largest prospective emergency department series, high-concentration continuous-flow nitrous oxide (70%) was found to be a safe agent for procedural sedation and analgesia when embedded in a comprehensive sedation program. Nitrous oxide also seems safe in children aged 1 to 3 years.