Predicting Peri-Operative Cardiorespiratory Adverse Events in Children with Idiopathic Pulmonary Arterial Hypertension Undergoing Cardiac Catheterization Using Echocardiography: A Cohort Study.

General anesthesia in children with idiopathic pulmonary arterial hypertension (PAH) carries an increased risk of peri-operative cardiorespiratory complications though risk stratifying individual children pre-operatively remains difficult. We report the incidence and echocardiographic risk factors for adverse events in children with PAH undergoing general anesthesia for cardiac catheterization. Echocardiographic, hemodynamic, and adverse event data from consecutive PAH patients are reported. A multivariable predictive model was developed from echocardiographic variables identified by Bayesian univariable logistic regression. Model performance was reported by area under the curve for receiver operating characteristics (AUCroc) and precision/recall (AUCpr) and a pre-operative scoring system derived (0-100). Ninety-three children underwent 158 cardiac catheterizations with mean age 8.8 ± 4.6 years. Adverse events (n = 42) occurred in 15 patients (16%) during 16 catheterizations (10%) including cardiopulmonary resuscitation (n = 5, 3%), electrocardiographic changes (n = 3, 2%), significant hypotension (n = 2, 1%), stridor (n = 1, 1%), and death (n = 2, 1%). A multivariable model (age, right ventricular dysfunction, and dilatation, pulmonary and tricuspid regurgitation severity, and maximal velocity) was highly predictive of adverse events (AUCroc 0.86, 95% CI 0.75 to 1.00; AUCpr 0.68, 95% CI 0.50 to 0.91; baseline AUCpr 0.10). Pre-operative risk scores were higher in those who had a subsequent adverse event (median 47, IQR 43 to 53) than in those who did not (median 23, IQR 15 to 33). Pre-operative echocardiography informs the risk of peri-operative adverse events and may therefore be useful both for consent and multi-disciplinary care planning.

Duct Stenting Versus Modified Blalock-Taussig Shunt in Neonates With Duct-Dependent Pulmonary Blood Flow: Associations With Clinical Outcomes in a Multicenter National Study.

BACKGROUND: Infants born with cardiac abnormalities causing dependence on the arterial duct for pulmonary blood flow are often palliated with a shunt usually between the subclavian artery and either pulmonary artery. A so-called modified Blalock-Taussig shunt allows progress through early life to an age and weight at which repair or further more stable palliation can be safely achieved. Modified Blalock-Taussig shunts continue to present concern for postprocedural instability and early mortality such that other alternatives continue to be explored. Duct stenting (DS) is emerging as one such alternative with potential for greater early stability and improved survival. METHODS: The purpose of this study was to compare postprocedural outcomes and survival to next-stage palliative or reparative surgery between patients undergoing a modified Blalock-Taussig shunt or a DS in infants with duct-dependent pulmonary blood flow. All patients undergoing cardiac surgery and congenital interventions in the United Kingdom are prospectively recruited to an externally validated national outcome audit. From this audit, participating UK centers identified infants <30 days of age undergoing either a Blalock-Taussig shunt or a DS for cardiac conditions with duct-dependent pulmonary blood flow between January 2012 and December 31, 2015. One hundred seventy-one patients underwent a modified Blalock-Taussig shunt, and in 83 patients, DS was attempted. Primary and secondary outcomes of survival and need for extracorporeal support were analyzed with multivariable logistic regression. Longer-term mortality before repair and reintervention were analyzed with Cox proportional hazards regression. All multivariable analyses accommodated a propensity score to balance patient characteristics between the groups. RESULTS: There was an early (to discharge) survival advantage for infants before next-stage surgery in the DS group (odds ratio, 4.24; 95% confidence interval, 1.37-13.14; P=0.012). There was also a difference in the need for postprocedural extracorporeal support in favor of the DS group (odds ratio, 0.22; 95% confidence interval, 0.05-1.05; P=0.058). Longer-term survival outcomes showed a reduced risk of death before repair in the DS group (hazard ratio, 0.25; 95% confidence interval, 0.07-0.85; P=0.026) but a slightly increased risk of reintervention (hazard ratio, 1.50; 95% confidence interval, 0.85-2.64; P=0.165). CONCLUSIONS: DS is emerging as a preferred alternative to a surgical shunt for neonatal palliation with evidence for greater postprocedural stability and improved patient survival to destination surgical treatment.

Outcome after transcatheter occlusion of patent ductus arteriosus in infants less than 6 kg: A national study from United Kingdom and Ireland.

OBJECTIVES: This study aimed to report our national experience with transcatheter patent ductus arteriosus (PDA) occlusion in infants weighing <6 kg. BACKGROUND: The technique of transcatheter PDA closure has evolved in the past two decades and is increasingly used in smaller patients but data on safety and efficacy are limited. METHODS: Patients weighing < 6 kg in whom transcatheter PDA occlusion was attempted in 13 tertiary paediatric cardiology units in the United Kingdom and Ireland were retrospectively analyzed to review the outcome and complications. RESULTS: A total of 408 patients underwent attempted transcatheter PDA closure between January 2004 and December 2014. The mean weight at catheterization was 4.9 ± 1.0 kg and mean age was 5.7 ± 3.0 months. Successful device implantation was achieved in 374 (92%) patients without major complication and of these, complete occlusion was achieved in 356 (95%) patients at last available follow-up. Device embolization occurred in 20 cases (5%). The incidence of device related obstruction to the left pulmonary artery or aorta and access related peripheral vascular injury were low. There were no deaths related to the procedure. CONCLUSIONS: Transcatheter closure of PDA can be accomplished in selected infants weighing <6 kg despite the manufacturer's recommended weight limit of 6 kg for most ductal occluders. The embolization rate is higher than previously reported in larger patients. Retrievability of the occluder and duct morphology needs careful consideration before deciding whether surgical ligation or transcatheter therapy is the better treatment option.

Doubly committed subarterial ventricular septal defect: A risk factor for aortic distortion in patients considered for percutaneous pulmonary valve implantation?

Percutaneous pulmonary valve implantation has gradually become the first line strategy for re-intervention for right ventricular outflow tract dysfunction during long-term follow-up after congenital cardiac surgery in many centers. We describe a case of a patient with double outlet right ventricle (Fallot's type) with a doubly committed subarterial ventricular septal defect, where the unique anatomy precluded percutaneous pulmonary valve implantation. © 2016 Wiley Periodicals, Inc.

Feasibility and safety of cardiopulmonary exercise testing in children with pulmonary hypertension.

BACKGROUND: Cardiopulmonary exercise testing helps prognosticate and guide treatment in adults with pulmonary hypertension. Concerns regarding its feasibility and safety limit its use in children with pulmonary hypertension. We aimed to assess the feasibility and safety of cardiopulmonary exercise testing in a large paediatric pulmonary hypertension cohort. METHODS: We reviewed all consecutive cardiopulmonary exercise tests performed between March, 2004 and November, 2013. The exclusion criteria were as follows: height <120 cm, World Health Organization class IV, history of exercise-induced syncope, or significant ischaemia/arrhythmias. Significant events recorded were as follows: patient-reported symptoms, arrhythmias, electrocardiogram abnormalities, and abnormal responses of arterial O2 saturation. RESULTS: A total of 98 children underwent 167 cardiopulmonary exercise tests. The median age was 14 years (inter-quartile range 10-15 years). Peak oxygen uptake was 20.4±7.3 ml/kg/minute, corresponding to 51.8±18.3% of the predicted value. Peak respiratory quotient was 1.08±0.16. All the tests except two were maximal, being terminated prematurely for clinical reasons. Baseline Oxygen saturation was 93.3±8.8% and was 81.2±19.5% at peak exercise. A drop in arterial O2 saturation >20% was observed in 23.5% of the patients. Moreover, five patients (3.0%) experienced dizziness, one requiring termination of cardiopulmonary exercise testing; five children (3.0%) experienced chest pain, with early cardiopulmonary exercise test termination in one patient. No significant arrhythmias or electrocardiogram changes were observed. CONCLUSION: Exercise testing in non-severely symptomatic children with pulmonary hypertension is safe and practical, and can be performed in a large number of children with pulmonary hypertension in a controlled environment with an experienced team. Side-effects were not serious and were resolved promptly with test termination.

Impairment of heart rate recovery after peak exercise predicts poor outcome after pediatric heart transplantation.

BACKGROUND: A blunted heart rate recovery (HRR) from peak exercise is associated with adverse outcome in adults with ischemic heart disease. We assessed HRR after pediatric heart transplantation (HTx) and its prognostic use. METHODS AND RESULTS: Between 2004 and 2010 we performed 360 maximal exercise tests (median, 2 tests/patient; range, 1-7) in 128 children (66 men; age at test, 14 ± 3 years) who received HTx (age, 8.5 ± 5.1 years) because of cardiomyopathy (66%) or congenital heart defects (34%). The change in heart rate from peak exercise to 1 minute of recovery was measured as HRR and was expressed as Z score calculated from reference data obtained in 160 healthy children. HRR was impaired soon after HTx (average in first 2 years Z=-1.9 ± 3.5) but improved afterward (Z=+0.52/y), such that HRR Z score normalized in most patients by 6 years after HTx (average, 0.6 ± 1.8). A subsequent decline in HRR Z score was noted from 6 years after HTx (rate of Z=-0.11/y). After 27 ± 15 months from the most recent exercise test, 19 patients died or were re-heart transplantation. For the follow-up after 6 years, HRR Z score was the only predictor of death/re-heart transplantation (P=0.003). Patients in the lowest quartile of HRR Z score had a much higher 5-year event rate (event-free rate, 29% versus 84%; hazard ratio, 7.0; P=0.0013). CONCLUSIONS: HRR is blunted soon after HTx but normalizes at ≈ 6 years, potentially as a result of parasympathetic reinnervation of the graft, but then declines. This late decline in HRR Z score is associated with worse outcome.

3D morphometric analysis of the arterial switch operation using in vivo MRI data.

The arterial switch operation (ASO) is widely used nowadays as the surgical strategy of choice to repair transposition of the great arteries (TGA). Residual morphological and geometrical abnormalities of the aorta, pulmonary arteries and coronary arteries, however, have not been fully studied in a three-dimensional (3D) domain. These morphometric complications might have implications on long-term outcomes of ASO patients, hence the need to explore them in detail and study them with reference to healthy controls of comparable age and body surface area. These anatomical characteristics were examined using 3D patient-specific anatomical models reconstructed from cardiovascular magnetic resonance (CMR) images of 20 ASO patients (mean age 14.4 ± 2.4 years, 16 males and 4 females) compared with healthy controls (mean age 15.2 ± 2.0 years, 17 males and 3 females). It was found that the aorta, pulmonary arteries and re-implanted coronary arteries of ASO patients were significantly different morphologically and geometrically to those of healthy controls. In particular, the aortic root was dilated, with abnormal 3D angulation and additional acute angulation of the curvature of the aortic arch in the ASO group compared with controls. This could theoretically impinge on aortic flow profiles and physiological stresses, which can act as a primer for the development of early atherosclerotic disease in the ASO population.

Atrial Septal Defect vs Ventricular Septal Defect: Getting the Right Mix in Transposition of the Great Arteries.

Transposition of the great arteries (TGA) is the second most common cyanotic congenital cardiac defect and affects around 4.7 in 10,000 live births. Patients present at birth with profound cyanosis due to inadequate oxygen delivery to the systemic circulation. Typical management after birth involves the administration of prostaglandins and oxygen while awaiting surgical repair. Balloon atrial septostomy may be performed depending on the adequacy of the interatrial communication. In this case report, we present a challenging case of TGA ventricular septal defect (VSD) and pulmonary stenosis (PS), demonstrating the importance of bedside clinical examination along with applying basic management principles. The patient underwent a right modified Blalock-Taussig-Thomas shunt (BTT) along with left pulmonary artery (LPA) reconstruction and main pulmonary artery band as an initial palliative procedure. The patient deteriorated post-operatively, with increasing desaturations and oxygen requirements. Though imaging suggested sufficient inter-circulatory mixing, the clinical picture of desaturation without respiratory distress and lack of response to oxygen and pulmonary vasodilatory therapy strongly suggested otherwise. The child therefore underwent a balloon atrial septostomy. Their clinical condition improved and they were discharged three days later. We describe this case's clinical course, medical and surgical management, and learning points.

Aortic arch shape is not associated with hypertensive response to exercise in patients with repaired congenital heart diseases.

BACKGROUND: Aortic arch geometry is linked to abnormal blood pressure (BP) response to maximum exercise. This study aims to quantitatively assess whether aortic arch geometry plays a role in blood pressure (BP) response to exercise. METHODS: 60 age- and BSA-matched subjects--20 post-aortic coarctation (CoA) repair, 20 transposition of great arteries post arterial switch operation (ASO) and 20 healthy controls--had a three-dimensional (3D), whole heart magnetic resonance angiography (MRA) at 1.5 Tesla, 3D geometric reconstructions created from the MRA. All subjects underwent cardiopulmonary exercise test on the same day as MRA using an ergometer cycle with manual BP measurements. Geometric analysis and their correlation with BP at peak exercise were assessed. RESULTS: Arch curvature was similarly acute in both the post-CoA and ASO cases [0.05 ± 0.01 vs. 0.05 ± 0.01 (1/mm/m²); p = 1.0] and significantly different to that of normal healthy controls [0.05 ± 0.01 vs. 0.03 ± 0.01 (1/mm/m²), p < 0.001]. Indexed transverse arch cross sectional area were significantly abnormal in the post-CoA cases compared to the ASO cases (117.8 ± 47.7 vs. 221.3 ± 44.6; p < 0.001) and controls (117.8 ± 47.7 vs. 157.5 ± 27.2 mm²; p = 0.003). BP response to peak exercise did not correlate with arch curvature (r = 0.203, p = 0.120), but showed inverse correlation with indexed minimum cross sectional area of transverse arch and isthmus (r = -0.364, p = 0.004), and ratios of minimum arch area/ descending diameter (r = -0.491, p < 0.001). CONCLUSION: Transverse arch and isthmus hypoplasia, rather than acute arch angulation plays a role in the pathophysiology of BP response to peak exercise following CoA repair.

Obstructive left heart disease in neonates with a "borderline" left ventricle: diagnostic challenges to choosing the best outcome.

In most newborns with left heart obstruction, the choice between a single-ventricle or biventricular management pathway is clear. However, in some neonates with a "borderline" left ventricle, this decision is difficult. Existing criteria do not reliably identify neonates who will have a good long-term outlook after biventricular repair (BVR). The objective of this study was prospective assessment of the outcome after BVR for newborns in whom the left ventricle (LV) was considered "borderline" by an expert group. This study was a prospective follow-up evaluation of neonates with obstructive left heart disease related to a "borderline" LV who underwent biventricular management between January 2005 and April 2011. Of 154 neonates who required intervention for left heart obstruction, 13 (7.8 %) met the echocardiographic (echo) inclusion criteria. At the first and last echo, the z-scores were respectively -1.76 ± 1.37 and -0.66 ± 1.47 (p = 0.013) for the mitral valve, -1.02 ± 1.57 and -0.23 ± 1.78 (p = 0.056) for the aortic valve, and 13.77 ± 5.8 and 20.85 ± 8.9 ml/m(2) (p = 0.006) for the LV end-diastolic volume. At this writing, all 12 survivors are clinically well. However, LV diastolic dysfunction and pulmonary artery hypertension was present in 5 (36 %) of 12 patients. Endocardial fibroelastosis (EFE) was detected in five patients at the last follow-up echo, but only in two patients preoperatively. Cardiac magnetic resonance imaging did not confirm EFE in any of assessed patients. The study authors could not reliably predict the outcome after BVR for neonates with left heart obstruction and a "borderline" LV. The presence of EFE with consequent diastolic dysfunction is more important than LV volume in determining the outcome. Prospective identification of EFE remains challenging.

Impact of reduction in right ventricular pressure and/or volume overload by percutaneous pulmonary valve implantation on biventricular response to exercise: an exercise stress real-time CMR study.

AIMS: To assess the impact of relief of pulmonary stenosis (PS) and pulmonary regurgitation (PR) by percutaneous pulmonary valve implantation (PPVI) on biventricular function during exercise stress. METHODS AND RESULTS: Seventeen patients, who underwent PPVI for PS or PR, were included. Magnetic resonance imaging was performed at rest and during supine exercise stress pre- and within 1-month post-PPVI, using a radial k - t SENSE real-time sequence. In patients with PS (n = 9), there was no reserve in right ventricular (RV) ejection fraction (EF) in response to exercise prior to PPVI (48.2 ± 12.1% at rest vs. 48.4 ± 14.8% during exercise, P = 0.87). Post-PPVI, reserve in RVEF in response to exercise was re-established (53.4 ± 15.0% at rest vs. 59.6 ± 17.3% during exercise, P = 0.003) with improvement in left ventricular stroke volume (LVSV) (45.4 ± 6.2 mL/m(2) at rest vs. 52.8 ± 8.8 mL/m(2) during exercise, P = 0.001). In patients with PR prior to PPVI (n = 8), LVSV during exercise increased (43.0 ± 8.5 vs. 54.3 ± 6.6 mL/m(2), P < 0.001) due to reduction in PR fraction during exercise (29.2 ± 5.2 vs. 13.6 ± 6.1%, P < 0.001). After PPVI, LVSV increased from rest to exercise (48.4 ± 8.8 vs. 57.2 ± 8.1 mL/m(2), P < 0.001) due to improved RVEF (45.5 ± 8.3 vs. 50.4 ± 6.9%, P = 0.001). There was a significantly higher increase in LVSV at exercise from pre- to post-PPVI in PS patients than in PR patients (ΔLVSV 8.2 ± 4.1 vs. Δ2.9 ± 4.1 mL/m(2), P = 0.01). The reduction in the RV outflow tract gradient correlated significantly with the improvement in LVSV during exercise (r = -0.73, P < 0.001). CONCLUSION: Percutaneous pulmonary valve implantation in patients with PS leads to restoration of reserve in RVEF during exercise stress. In patients with PR, SV augmentation improves only mildly post-PPVI. Improvement in SV augmentation during exercise stress after PPVI is dependent mainly on afterload reduction.

Impact of Tracheal Arborization and Lung Hypoplasia in Repair of Pulmonary Artery Sling in Combination With Long-Segment Tracheal Stenosis.

Background: Reimplantation of the left pulmonary artery (LPA) and slide tracheoplasty has been our standard approach of care for patients with pulmonary artery sling (PAS) and tracheal stenosis. We present our experience, with emphasis on tracheal arborization and hypoplastic lungs; and their impact on long-term outcome of children with PAS and tracheal stenosis. Methods: It is a retrospective comparative study. Data were classified and analyzed based on the type of tracheobronchial arborization and normal versus hypoplastic lungs. Results: Seventy-five children operated between January 1994 and December 2019 (67 with normal lungs and 8 with lung hypoplasia/agenesis) were included. Patients with hypoplastic lungs had higher rates of preoperative ventilation (87.5%), postoperative ventilation (10 vs 8 days, P = .621), and mortality (50% vs 9%, P = .009) compared with those with normal lungs. Nineteen patients had tracheal bronchus (TB) variety and 30 patients had congenital long-segment tracheal stenosis (CLSTS) variety of tracheobronchial arborization. Endoscopic intervention was needed in 47.4% of patients with TB type and 60% with CLSTS type. CLSTS patients had higher rates of preoperative ventilation (60% vs 47.4%, P = .386), longer periods of postoperative ventilation (13 vs 6.5 days, P = .006), and ICU stay (15 vs 11 days, P = .714) compared with TB type. Conclusion: Surgical repair of PAS with tracheal stenosis has good long-term outcomes. All variations of tracheal anatomy can be managed with slide tracheoplasty. Persistence of airway problems requires intervention during follow-up as tracheal stenosis continues to be the Achilles heel.

Peak oxygen uptake correlates with survival without clinical deterioration in ambulatory children with dilated cardiomyopathy.

BACKGROUND: Children stable at home with dilated cardiomyopathy remain at risk of death; there is evidence of survival benefit for transplantation out to 4 years postoperatively. The limited supply of donor organs makes risk stratification imperative, but although cardiopulmonary exercise test is well established as a powerful tool in adults with heart failure, no published studies have linked oxygen uptake to prognosis in children. METHODS AND RESULTS: Between 2001 and 2009, using cardiopulmonary exercise test and echocardiography, we studied 82 children (mean age, 13.5±2.3 years) with dilated cardiomyopathy. All were ambulatory, outpatients, and >120 cm in height. All children completed a symptom-limited maximal exercise test. Resting left ventricular shortening fraction was 20±9%; peak heart rate was 87±13% of predicted; peak oxygen uptake (VO(2)) was 67±22% of predicted; and ventilatory efficiency was 32±8. Follow-up was available for 100% of the children, and was a mean of 32.3±7.5 months. Eighteen patients reached the defined clinical end point of death or listing for urgent heart transplantation. On univariate analysis, left ventricular shortening fraction, peak heart rate, peak VO(2), peak systolic blood pressure, and ventilatory efficiency were all associated with adverse outcome. On multivariable Cox analysis, only peak VO(2) (P=0.003) was associated with the study end point. Patients with a peak VO(2) ≤62% of predicted had a higher 24-month event rate (50.6% versus 4.4%; hazard ratio, 10.78). CONCLUSIONS: We have demonstrated that a cardiopulmonary exercise test is feasible in ambulatory children with dilated cardiomyopathy who are >120 cm height and for the first time have linked peak VO(2) with outcome in children.

Physiologic decrease of ventilatory response to exercise in the second decade of life in healthy children.

BACKGROUND: Cardiopulmonary exercise testing is increasingly used in children with congenital heart defects. Because of changes related to growth, the interpretation of exercise test results heavily relies on the presence of normative data. There is growing interest in the assessment of the ventilatory response to exercise in children with congenital heart disease, but normative data are lacking. METHODS: We studied 243 consecutive children (age, 13.2 ± 2.1 years; 128 boys) with maximal cardiopulmonary exercise testing. All children had normal clinical examination and echocardiograms. In all children, the slope of the relationship between minute ventilation and carbon dioxide production (VE/VCO(2) slope) was calculated using both only data until the respiratory compensation point (VE/VCO(2RC)) and using data until peak exercise (VE/VCO(2Peak)). RESULTS: The exercise test was maximal in all children (peak respiratory exchange ratio, 1.2 ± 0.1). For all the cohorts, VE/VCO(2Peak) slope was 28.2 ± 3.7; and VE/VCO(2RC) slope was 24.5 ± 3.0, whereas peak oxygen uptake was 94.6% ± 14.0% of predicted value. Baseline spirometric function was normal in all children (vital capacity, 100% ± 14% and forced expired volume in the first second 97% ± 13% of predicted). From the age of 10 to 16 years, we observed a progressive decrease in both VE/VCO(2Peak) and VE/VCO(2RC) slopes (-0.833 and -0.705 per each year), with the highest reduction observed in boys. Gender-specific percentiles for both VE/VCO(2Peak) and VE/VCO(2RC) slopes were constructed. CONCLUSION: Ventilatory response to exercise expressed as VE/VCO(2) slope seems to decrease progressively in the second decade of life. Because of age-related changes, interpretation of VE/VCO(2) slopes in this age range should be based on the reported percentiles rather than on the absolute values.

Predictors of morbidity and mortality in contemporary Fontan patients: results from a multicenter study including cardiopulmonary exercise testing in 321 patients.

AIMS: previous studies have established an association between exercise intolerance and increased morbidity and mortality in congenital heart disease patients. We aimed to clarify if exercise intolerance is associated with poor outcome in Fontan patients and to identify risk factors for mortality, transplantation, and cardiac-related hospitalization. METHODS AND RESULTS: a total of 321 Fontan patients (57% male, mean age 20.9 ± 8.6 years) who underwent cardiopulmonary exercise testing (CPET) at four major European centres between 1997 and 2008 were included. During a median follow-up of 21 months, 22 patients died and 6 patients underwent cardiac transplantation (8.7%), resulting in an estimated 5-year transplant-free survival of 86%. Parameters of CPET were strongly related to increased risk of hospitalization, but-with the exception of heart rate reserve-unrelated to risk of death or transplantation. In contrast, patients with clinically relevant arrhythmia had a 6.0-fold increased risk of death or transplantation (P < 0.001). Furthermore, patients with atriopulmonary/-ventricular Fontan had a 3.7-fold increased risk of death or transplantation compared with total cavopulmonary connection patients (P= 0.009). The combination of clinically relevant arrhythmia, atriopulmonary/-ventricular Fontan, and signs of symptomatic or decompensated heart failure was associated with a particularly poor outcome (3-year mortality 25%). CONCLUSION: on short-term follow-up, most parameters of CPET are associated with increased risk of hospitalization but not death or transplantation in contemporary Fontan patients. Only decreased heart rate reserve and a history of clinically relevant arrhythmia, atriopulmonary/-ventricular Fontan, and/or heart failure requiring diuretic therapy are associated with poor prognosis, potentially identifying patients requiring medical and/or surgical attention.

Importance of Acute Anterior Angulation in Double Aortic Arch Needing Attention at Primary Surgery.

BACKGROUND: Vascular rings are rare congenital abnormalities of the aortic arch. There are many embryological variants including a double aortic arch. In symptomatic children, division of ring and release of airway structures may be sufficient. Persistence of symptoms can be related to an anterior angle formed between the two arches. The aim of this study is to evaluate the clinical efficacy in improving symptoms and on changing this angle at the primary surgery. METHODS: All children who had surgery for double aortic arch between 2005 and 2020, were studied. Relevant factors were analyzed for persistent symptoms including anatomical substrates and surgical details. RESULTS: A total of 87 out of 224 children had surgery for a double aortic arch. At presentation, airway symptoms (n = 74/87) were more common than esophageal symptoms (n = 27/87). Early onset symptoms within 1 year were seen in 49 children. In addition to division of one arch, surgical steps also included realigning the anterior left arch, thereby eliminating the acute angle in 36 children (after 2014). After surgery, symptom relief within 12 months following surgery was seen in 64% of children (56 out of 87) but in 27 out of 36 children (75%) with additional surgical modification, as against 29 out of 51 (57%) in those with division of the arch. Symptoms persisted beyond 1 year needing reintervention in eight children. CONCLUSION: Anterior arch angulation plays an important role in double aortic arch by causing a "nutcracker" phenomenon. Repair in double aortic arch should consider this aspect and include modification of surgical steps by realigning the corresponding aortic arch branches and an anterior pexy in selected cases.

Comparison of bare metal stenting and percutaneous pulmonary valve implantation for treatment of right ventricular outflow tract obstruction: use of an x-ray/magnetic resonance hybrid laboratory for acute physiological assessment.

BACKGROUND: Treatment of right ventricular outflow tract obstruction is possible with a bare metal stent (BMS), although this treatment causes pulmonary regurgitation. In this study, we assessed the acute physiological effects of BMS versus percutaneous pulmonary valve implantation (PPVI) using an x-ray/magnetic resonance hybrid laboratory. METHODS AND RESULTS: Fourteen consecutive children (median age, 12.9 years) with significant right ventricular outflow tract obstruction underwent BMS followed by PPVI. Magnetic resonance imaging (ventricular volumes and function and great vessel blood flow) and hemodynamic assessment (invasive pressure measurements) were performed before BMS, after BMS, and after PPVI; all were performed under general anesthesia in an x-ray/magnetic resonance hybrid laboratory. BMS significantly reduced the ratio of right ventricular to systemic pressure (0.75+/-0.17% versus 0.41+/-0.14%; P<0.001) with no further change after PPVI (0.42+/-0.11; P=1.0). However, BMS resulted in free pulmonary regurgitation (21.3+/-10.7% versus 41.4+/-7.5%; P<0.001), which was nearly abolished after PPVI (3.6+/-5.6%; P<0.001). Effective right ventricular stroke volume (right ventricular stroke volume minus pulmonary regurgitant volume) after BMS remained unchanged (33.8+/-7.3 versus 32.6+/-8.7 mL/m2; P=1.0) but was significantly increased after revalvulation with PPVI (41.0+/-8.0 mL/m2; P=0.004). These improvements after PPVI were accompanied by a significant heart rate reduction (75.5+/-17.7 bpm after BMS versus 69.0+/-16.9 bpm after PPVI; P=0.006) at maintained cardiac output (2.5+/-0.5 versus 2.4+/-0.5 versus 2.7+/-0.5 mL x min(-1) x m(-2); P=0.14). CONCLUSIONS: Using an x-ray/magnetic resonance hybrid laboratory, we have demonstrated the superior acute hemodynamic effects of PPVI over BMS in patients with right ventricular outflow tract obstruction.

The EPICure study: maximal exercise and physical activity in school children born extremely preterm.

RATIONALE: Evidence regarding exercise capacity and physical activity in children born extremely preterm (EP) is limited. Since survivors remain at high risk for developing bronchopulmonary dysplasia (BPD) and long-term pulmonary sequelae, reductions in exercise capacity and activity levels may be present. OBJECTIVES: To compare maximal exercise ventilation characteristics and physical activity levels at 11 years of age in children born EP (<25 completed weeks gestation) with those of full-term controls. METHODS: Participants performed spirometry, body plethysmography and gas transfer testing. A peak exercise test was performed on a cycle ergometer. Physical activity was monitored by accelerometry for 7 days. RESULTS: Lung function and exercise results were obtained in 38 EP children (71% prior BPD) and 38 controls. Those born EP had significantly lower Z-scores (mean (95% CI) of difference) for forced expiratory volume in 1 s (FEV(1); -1.74 (-2.25 to -1.23) and gas transfer (-0.73 (-1.31 to -0.17), and significantly greater Z-scores for residual volume (RV; 0.58 (0.10 to 1.10)) and RV/total lung capacity (TLC; 0.74 (0.29 to 1.19)). EP birth was associated with a significant reduction in peak oxygen consumption. EP children employed greater breathing frequencies and lower tidal volumes during peak exercise. No differences were observed in physical activity between groups. CONCLUSIONS: The reduction in peak oxygen consumption in children born EP, and alterations in ventilatory adaptations during peak exercise were not explained by differences in physical activity, but probably reflects the long-term pathophysiological impact of EP birth.

A modelling study of atrial septostomy for pulmonary arterial hypertension, and its effect on the state of tissue oxygenation and systemic blood flow.

Atrial septostomy is performed in patients with severe pulmonary arterial hypertension, and has been shown to improve symptoms, quality of life and survival. Despite recognized clinical benefits, the underlying pathophysiologic mechanisms are poorly understood. We aimed to assess the effects of right-to-left shunting on arterial delivery of oxygen, mixed venous content of oxygen, and systemic cardiac output in patients with pulmonary arterial hypertension and a fixed flow of blood to the lungs. We formulated equations defining the mandatory relationship between physiologic variables and delivery of oxygen in patients with right-to-left shunting. Using calculus and computer modelling, we considered the simultaneous effects of right-to-left shunting on physiologies with different pulmonary flows, total metabolic rates, and capacities for carrying oxygen. Our study indicates that, when the flow of blood to the lungs is fixed, increasing right-to-left shunting improves systemic cardiac output, arterial blood pressure, and arterial delivery of oxygen. In contrast, the mixed venous content of oxygen, which mirrors the average state of tissue oxygenation, remains unchanged. Our model suggests that increasing the volume of right-to-left shunting cannot compensate for right ventricular failure. Atrial septostomy in the setting of pulmonary arterial hypertension, therefore, increases the arterial delivery of oxygen, but the mixed systemic saturation of oxygen, arguably the most important index of tissue oxygenation, stays constant. Our data suggest that the clinically observed beneficial effects of atrial septostomy are the result of improved flow of blood rather than augmented tissue oxygenation, provided that right ventricular function is adequate.