Mid- and long-term outcomes after surgical correction of subaortic stenosis: a 27-year experience.

OBJECTIVES: We reviewed the mid- and long-term surgical outcomes of patients with subaortic stenosis (SAS). METHODS: Patients operated for SAS from April 1990 to August 2016 were reviewed retrospectively. Patients with major associations such as aortic arch obstruction were excluded. Time to reintervention and predictors of recurrence were assessed using Kaplan-Meier analysis, log-rank test and uni/multivariable Cox regression. RESULTS: 120 patients at a median age of 4.7 years (interquartile range 2.9, 8.1) underwent primary operation (median peak preoperative left ventricular outflow tract gradient 52.5 mmHg, interquartile range 40, 70) involving fibrous tissue excision (n = 120) with septal myectomy (93%; n = 112) as the procedure of choice.At median follow-up of 13 years (interquartile range 7, 18), freedom from reintervention at 1, 3, 5 and 10 years was 99% (95% confidence interval 94%, 99%), 94% (87%, 97%), 93% (86%, 96%) and 90% (82%, 94%), respectively. Recurrence occurred in 18% (n = 20) with 15 patients undergoing reinterventions, 13 of whom required radical reoperation. Multivariable analysis revealed higher preoperative peak left ventricular outflow tract gradient (hazard risk 1.06, confidence interval 1.03, 1.09, P < 0.001), and presence of bicuspid aortic valve (hazard risk 14.13, confidence interval 3.32, 60.1, P < 0.001) as predictors for reintervention. Mild/moderate aortic regurgitation occurred in 49% (n = 55) of patients at the most recent follow-up. CONCLUSIONS: Reintervention for recurrent SAS is common, predicted by higher preoperative peak left ventricular outflow tract gradient, and presence of bicuspid aortic valve, and frequently involves a radical procedure. Aortic regurgitation is a major consequence of SAS, but its severity usually remains low. CLINICAL REGISTRATION NUMBER: SCHN HREC reference number 2019/ETH02729, approved on 09 July 2019.

Modified pulmonary artery banding: A novel strategy for balancing pulmonary blood flow with transposed great arteries.

OBJECTIVE: To study the outcomes of a novel modified pulmonary artery banding (mPAB) technique used for staged repair of a subset of patients with complex transposition physiology. METHODS: A total of 13 patients who underwent mPAB during their staged repair (biventricular repair [BVR], n = 6) or palliation (1-1/2 repair, n = 1; univentricular repair [UVR], n = 6) from 2004 to 2020 were studied retrospectively. A restrictive interposition graft was used to reconstruct the main PA between the pulmonary root and the distal pulmonary confluence, functioning as a mPAB. Twelve of the 13 patients (92.3%) underwent a concurrent arterial switch operation (ASO), of which 6 were palliative ASOs for 1-1/2 repair (n = 1) or UVR (n = 5). Patient weight and cardiac anatomy determined the size of interposition graft. RESULTS: The disease spectrum included dextro transposition of the great arteries (d-TGA) with multiple ventricular septal defects (VSDs) (n = 4), Taussig-Bing anomaly (n = 3), d-TGA with VSD and hypoplastic right ventricle (RV) (n = 3), double-inlet left ventricle with l-TGA (n = 2), and congenitally corrected TGA with double-outlet RV (n = 1). The Lecompte procedure was performed in 10 patients. Predischarge echocardiography revealed a band gradient of 61 mm Hg (interquartile range [IQR], 40-90 mm Hg) for BVR/1-1/2 ventricular repair (n = 7) and 49 mm Hg (IQR, 37-61 mm Hg) for UVR (n = 6). Survival was 100% at a median follow-up of 3.7 years (IQR, 2.6-4.0 years). CONCLUSIONS: The mPAB technique is effective and reproducible for staged BVR or UVR for patients with TGA. It effectively regulates pulmonary blood flow, may reduce neopulmonary root distortion, and eliminates complications associated with band migration in standard PAB.

Outcomes Following Heterotopic Placement of Right Ventricle to Pulmonary Artery Conduits.

BACKGROUND: We sought to evaluate the outcomes following right ventricle to pulmonary artery (RV-PA) conduit placement in pediatric patients, excluding those with a RV-PA conduit for the Ross procedure which is associated with improved conduit durability, partly related to its orthotopic position. METHODS: Outcomes for 119 patients who underwent RV-PA conduit placement at a single institution from January 2004 to December 2016 were reviewed. Primary outcome measures were reintervention-free survival (RFS) and overall survival. Survival analyses were performed using the Kaplan-Meier method, and risk factors associated with reintervention were evaluated. RESULTS: The median age at the time of conduit placement was 6 months (interquartile range, IQR: 1-14), and the median length of follow-up was 63 months (range: 0-156). During follow-up, 39 patients required conduit-related reintervention, while 6 patients died perioperatively with an overall survival of 90% at 10 years. Among the remaining 113 patients, the RFS at one, five, and ten years was 91% (84%-95%), 72% (60%-80%), and 33% (16%-50%), respectively. The median time to conduit replacement in the series was 43.5 months (IQR: 19.3-76.2). The use of a pulmonary homograft was associated with improved RFS (P = .03), and this was particularly pronounced in comparison with aortic homografts in neonates. Infection was the indication for replacement in only one patient. CONCLUSIONS: The majority of the conduits placed during the neonatal period required conduit replacement before the age of five years. Endocarditis was not a common indication for replacement. In neonates and infants, we prefer pulmonary homografts for most indications.

Impact of High-Risk Characteristics in Hypoplastic Left Heart Syndrome.

BACKGROUND: Management of hypoplastic left heart syndrome (HLHS) presents many challenges. We describe our institutional outcomes for management of patients with HLHS over the past 12 years and highlight our strategy for those with highly restrictive/intact interatrial septum (R/I-IAS). METHODS: Eighty-eight neonates with HLHS underwent surgical treatment, divided equally into Era-I (n = 44, April 2006 to February 2013) and Era-II (n = 44, March 2013 to June 2018). Up to 2013, all patients with R/I-IAS were delivered at an adjacent adult hospital and then moved to our hospital for intensive care and management. From 2014, these patients were delivered at a co-located theatre in our hospital with immediate atrial septectomy. The hybrid approach was occasionally used with preference for the Norwood procedure for suitable candidates. RESULTS: One-year survival after Norwood procedure was 62.5% and 80% for Era-I and Era-II (P = not significant (ns)), respectively, and 41% of patients were categorized as high risk using conventional criteria. Survival at 1 year differed significantly between high-risk and standard-risk patients (P = 0.01). For high-risk patients, survival increased from 42% to 65% between eras (P = ns). In the R/I-IAS subgroup (n = 15), 11 underwent Norwood procedure after emergency atrial septectomy. Of these, seven born at the adjacent adult hospital had 40% survival to stage II versus 60% for the four born at the colocated theatre. Delivery in a colocated theatre reduced the birth-to-cardiopulmonary bypass median time from 445 (150-660) to 62 (52-71) minutes. CONCLUSION: Reported surgical outcomes are comparable to multicenter reports and international databases. Proactive management for risk factors such as R/I-IAS may contribute to improved overall outcomes.

Neonatal Ebstein Anomaly: A 30-year Institutional Review.

This study aimed to review our 30-year, single-center experience of neonates admitted with Ebstein anomaly. Between January 1985 and August 2015, 80 neonates with Ebstein anomaly were managed. The primary outcome measures were early and late survival, freedom from reoperation, and functional status. Pulmonary atresia or critical stenosis occurred in 18 neonates. Twenty-seven (34%) patients required intervention: 13 systemic-to-pulmonary shunts, 5 balloon pulmonary valvotomy, 3 relief of right ventricular outflow tract obstruction, 3 Starnes procedures, and 3 other procedures. Sixty-nine (86%) of the neonates survived to hospital discharge. Overall 15-year survival estimate was 67% (SE = 6.5), with a superior prognosis for those able to be managed medically (15-year survival of 79%, SE = 7.0) compared with those in whom surgical or catheter intervention was undertaken (15-year survival of 45%, SE = 11.2, P = 0.005). For early survivors of neonatal surgery, freedom from reoperation at 10 years was 16% (SE = 8.5). For long-term survivors, 96% were classified as New York Heart Association Class I or II. Neonates with Ebstein anomaly who can be managed without intervention have a good prognosis. Substantial mortality risk remains in those who require intervention, especially those complicated by pulmonary atresia.

Improved long-term outcomes in double-inlet left ventricle and tricuspid atresia with transposed great arteries: systemic outflow tract obstruction present at birth defines long-term outcome.

OBJECTIVES: In 2 subtypes of functional single ventricle, double inlet left ventricle (DILV) and tricuspid atresia with transposed great arteries (TA-TGA), systemic output passes through an outflow chamber before entering the aorta. Intracardiac obstruction to this pathway causing systemic outflow tract obstruction (SOTO) may be present at birth or develop over time. Long-term survival after Fontan has not been defined. We defined outcomes utilizing records from 2 centres that were cross-checked with data from a bi-national Fontan Registry for completeness and accuracy. METHODS: Two hundred and eleven patients were identified, 59 TA-TGA,152 DILV. Median follow-up was 17 years (range 4 days to 49.8 years). The Kaplan-Meier method was used for all of the time to event analyses and the log-rank test was used to compare the time-to-events. Cox proportional hazard models were used to test the association between potential predictors and time-to-event end-points. RESULTS: TA-TGA had reduced survival compared to DILV (cumulative risk of death 28.8% vs 11%, hazard ratio (HR) 3.1 (95% confidence interval (CI) 1.6-6.1), P = 0.001). In both groups, SOTO at birth carried a worse prognosis HR 3.54 (1.36-9.2, P = 0.01). SOTO was not more common in either morphology at birth ( P = 0.20). Periprocedural mortality accounted for 40% of deaths. Fontan was achieved in 82%, DILV were more likely to achieve Fontan than TA-TGA (91% vs 60%, P <0.001). After Fontan there were 9 deaths (4%) with no difference according to morphology. CONCLUSIONS: Patients with TA-TGA have poorer outcomes than those with DILV, affecting survival and likelihood of achieving Fontan. SOTO at birth carries a high risk of mortality suggesting that, when present, initial surgical management should address this.

Somatic mutations in NKX2­5, GATA4, and HAND1 are not a common cause of tetralogy of Fallot or hypoplastic left heart.

The majority of congenital heart disease (CHD) occurs as a sporadic finding, with a minority of cases associated with a known genetic abnormality. Combinations of genetic and environmental factors are implicated, with the recent and intriguing hypothesis that an apparently high rate of somatic mutations might explain some sporadic CHD. We used samples of right ventricular myocardium from patients undergoing surgical repair of tetralogy of Fallot (TOF) and hypoplastic left heart (HLH) to examine the incidence of somatic mutation in cardiac tissue. TOF is a common form of cyanotic CHD, occurring in 3.3 per 10,000 live births. HLH is a rare defect in which the left side of the heart is severely under-developed. Both are severe malformations whose genetic etiology is largely unknown. We carried out direct sequence analysis of the NKX2­5 and GATA4 genes from fresh frozen cardiac tissues and matched blood samples of nine TOF patients. Analysis of NKX2­5, GATA4, and HAND1 was performed from cardiac tissue of 24 HLH patients and three matched blood samples. No somatic or germline mutations were identified in the TOF or HLH patients. Although limited by sample size, our study suggests that somatic mutations in NKX2­5 and GATA4 are not a common cause of isolated TOF or HLH.

Fetal and post-natal diagnosis of major congenital heart disease: implications for medical and psychological care in the current era.

AIM: The fetal or post-natal diagnosis of major congenital cardiac abnormality has important medical and psychological consequences. METHODS: We reviewed infants who underwent cardiac surgery in the first year of life at the Heart Centre for Children, The Children's Hospital at Westmead during 2009. The aims of this study were to: (i) examine the key features of cardiac diagnosis and clinical outcome, and (ii) consider how these data can inform priorities for the delivery of clinical services. RESULTS: Over the 12-month study period, a first cardiac surgical procedure was performed on 195 infants, with 85 infants (44%) diagnosed in the antenatal period. Of the total sample, a subset of 90 babies (46%) underwent their first procedure in the neonatal period, with 62% having had a fetal diagnosis. Major intracardiac lesions including truncus arteriosus (100%), single ventricular lesions (83%), pulmonary atresia with ventricular septal defect (78%) and transposition of the great arteries (53%) were diagnosed prior to birth. Improved haemodynamic stability at initial presentation was found in those with a fetal diagnosis. The overall mortality rate for all patients was 6.1% at 12 months, with a higher mortality in infants with single ventricle. CONCLUSIONS: The contemporary paradigm of care for infants with major congenital heart disease requires a multidisciplinary approach to care, with improvements in clinician-clinician and clinician-family communication, and psychological support and education for families. Changes in the allocation of resources are required to meet this model of best practice.

Five-year analysis of operative mortality and neonatal outcomes in congenital heart disease.

BACKGROUND: We sought to compare overall mortality with neonatal outcomes over a five year period to define risk factors for mortality and service development priorities. METHODS: A retrospective cohort study of surgical outcomes following repair or palliation of structural congenital heart defects January 2005-2010. We defined mortality according to contemporary international guidelines and classified surgical procedures using the Risk Adjustment in Congenital Heart Surgery (RACHS-1) score. The effect of age and weight at operation on mortality and annual variation in case-complexity and surgeon case-mix were assessed. Subgroup analysis was performed in patients who were ≤30 days at operation (neonates). RESULTS: Overall mortality within 30 days of operation or prior to hospital discharge was 1.3 and 1.9%, respectively. Mortality was higher in neonates (6.8%) and low birth weight infants (≤2.5kg) (12.1%). Mortality was similar in bypass versus non-bypass procedures (odds ratio 0.74, p=0.425). Annual mortality rates were consistent despite a marked increase in case-complexity. Neonates overall required longer periods of intensive care support and were more likely to suffer serious complications compared to older children. Age, weight and RACHS-1 score were independent risk factors for mortality on multivariate analysis. In neonates undergoing bypass procedures, only RACHS-1 score was a significant risk factor. CONCLUSIONS: This study provides an accurate and contemporary audit of mortality risk associated with congenital heart surgery. Outcomes compare favourably to international benchmarks but highlight the risks of morbidity and mortality associated with neonatal cardiac surgery.

GATA4 mutations in 357 unrelated patients with congenital heart malformation.

Congenital heart disease (CHD) represents one of the most common birth defects, but the genetic causes remain largely unknown. Mutations in GATA4, encoding a zinc finger transcription factor with a pivotal role in heart development, have been associated with CHD in several familial cases and a small subset of sporadic patients. To estimate the pathogenetic role of GATA4 in CHD, we screened for mutations in 357 unrelated patients with different congenital heart malformations. In addition to nine synonymous changes, we identified two known (A411V and D425N) and two novel putative mutations (G69D and P163R) in five patients with atrial or ventricular septal defects that were not seen in control subjects. The four mutations did not show altered GATA4 transcriptional activity in synergy with the transcription factors NKX2-5 and TBX20. Our data expand the spectrum of mutations associated with cardiac septal defects but do not support GATA4 mutations as a common cause of CHD.

Myocardial membrane injury in pediatric cardiac surgery: An animal model.

OBJECTIVE: Reduced myocardial performance invariably follows pediatric cardiac surgery and is manifested by a low cardiac output state in its severest form. The role of myocardial membrane proteins in this setting is unknown. Dystrophin and dysferlin are involved in membrane integrity, whereas aquaporins selectively transport water. These proteins were examined in a model of pediatric cardiac surgery, together with a trial of poloxamer 188, which may reduce membrane injury. METHODS: Eight lambs were randomized to saline with or without poloxamer 188. Lambs underwent 2 hours of cardiopulmonary bypass and aortic crossclamping. After a further 9 hours of monitoring, the hearts were assessed for water content, capillary leak, and protein expression. RESULTS: Dystrophin expression was unaffected by ischemia/reperfusion, but dysferlin expression was reduced. Aquaporin 1 protein increased after ischemia/reperfusion. Poloxamer 188 administration was associated with supranormal levels of dystrophin, preservation of dysferlin expression, and normalization of aquaporin 1 expression. Poloxamer 188 was associated with less capillary leak, maintained colloid osmotic pressure, and less hemodilution. Poloxamer 188 was associated with an improved hemodynamic profile (higher blood pressure, higher venous saturation, and lower lactate), although the heart rate tended to be higher. CONCLUSIONS: Changes in protein expression within the myocardial membrane were found in a clinically relevant model of pediatric cardiac surgery. Indicators of reduced performance, such as lower blood pressure and lower oxygen delivery, were lessened in association with the administration of the membrane protecting poloxamer 188. Poloxamer 188 was also associated with potentially beneficial changes in membrane protein expression, reduced capillary leakage, and less hemodilution.

Transposition of the great arteries, interrupted inferior vena cava and intestinal atresia: a new association?

We present a neonate with transposition of the great arteries, ventricular septal defect, inferior vena caval interruption with azygous continuation and intestinal atresia. This concurrence of anomalies has not been previously reported.

Myocardial ischemia is more important than the effects of cardiopulmonary bypass on myocardial water handling and postoperative dysfunction: a pediatric animal model.

OBJECTIVES: Low cardiac output state is the principal cause of morbidity after surgical intervention for congenital heart disease. Myocardial ischemia-reperfusion injury, apoptosis, capillary leak syndrome, and myocardial edema are associated factors. We established a clinically relevant model to examine relationships between myocardial ischemia, edema, and cardiac dysfunction and to assess the role of the water transport proteins aquaporins. METHODS: Sixteen lambs were studied. Seven were control animals not undergoing cardiopulmonary bypass, and 9 underwent bypass. Six had 90 minutes of aortic crossclamping with blood cardioplegia and moderate hypothermia. The remaining 3 underwent cardiopulmonary bypass without aortic crossclamping. Hemodynamic and biochemical data were recorded, and myocardial edema, apoptotic markers, and aquaporin expression were determined after death. RESULTS: The group undergoing cardiopulmonary bypass with aortic crossclamping had a low cardiac output state, with early postoperative tachycardia, hypotension, increased serum lactate levels, and impaired tissue oxygen delivery (P < .05) compared with the group undergoing cardiopulmonary bypass without aortic crossclamping. The lambs undergoing cardiopulmonary bypass with aortic crossclamping had increased myocardial water (P < .05) compared with those not undergoing cardiopulmonary bypass and a 2-fold increase in aquaporin 1 mRNA expression (P < .05) compared with those not undergoing cardiopulmonary bypass and those undergoing cardiopulmonary bypass without aortic crossclamping. CONCLUSIONS: A temporal association between hemodynamic dysfunction, myocardial edema, and increased aquaporin 1 expression was demonstrated. Cardiopulmonary bypass without ischemia was associated with minimal edema, negligible myocardial dysfunction, and static aquaporin expression. Ischemic reperfusion injury is the main cause of myocardial edema and myocardial dysfunction, but a causal relationship between edema and dysfunction remains to be proved.

Mutations in cardiac T-box factor gene TBX20 are associated with diverse cardiac pathologies, including defects of septation and valvulogenesis and cardiomyopathy.

The T-box family transcription factor gene TBX20 acts in a conserved regulatory network, guiding heart formation and patterning in diverse species. Mouse Tbx20 is expressed in cardiac progenitor cells, differentiating cardiomyocytes, and developing valvular tissue, and its deletion or RNA interference-mediated knockdown is catastrophic for heart development. TBX20 interacts physically, functionally, and genetically with other cardiac transcription factors, including NKX2-5, GATA4, and TBX5, mutations of which cause congenital heart disease (CHD). Here, we report nonsense (Q195X) and missense (I152M) germline mutations within the T-box DNA-binding domain of human TBX20 that were associated with a family history of CHD and a complex spectrum of developmental anomalies, including defects in septation, chamber growth, and valvulogenesis. Biophysical characterization of wild-type and mutant proteins indicated how the missense mutation disrupts the structure and function of the TBX20 T-box. Dilated cardiomyopathy was a feature of the TBX20 mutant phenotype in humans and mice, suggesting that mutations in developmental transcription factors can provide a sensitized template for adult-onset heart disease. Our findings are the first to link TBX20 mutations to human pathology. They provide insights into how mutation of different genes in an interactive regulatory circuit lead to diverse clinical phenotypes, with implications for diagnosis, genetic screening, and patient follow-up.

Levosimendan for low cardiac output: a pediatric experience.

This was a retrospective observational study in a pediatric intensive care unit, in which 19 patients received levosimendan. There were no adverse events attributable to levosimendan and no instances where the clinical condition worsened after administration. Arterial lactate levels decreased significantly following levosimendan administration during cardiopulmonary bypass for anticipated low cardiac output. In those with established low cardiac output, trends toward improved hemodynamics were seen, with heart rate reduction, an increase in mean blood pressure, a reduction in arterial lactate, and reduced conventional inotrope use. Levosimendan was safely used in a small number of pediatric patients with established low cardiac output state who demonstrated improved hemodynamics and tissue perfusion, with a tendency to reduced conventional inotrope usage, and this warrants its evaluation as an inotrope in the pediatric population.

Clinical assessment of cardiac performance in infants and children following cardiac surgery.

OBJECTIVE: To compare clinical assessment of cardiac performance with an invasive method of haemodynamic monitoring. DESIGN AND SETTING: Prospective observational study in a 16-bed tertiary paediatric intensive care unit. PATIENTS AND PARTICIPANTS: Infants and children undergoing cardiopulmonary bypass and surgical repair of congenital heart lesions. INTERVENTIONS: Based on physical examination and routinely available haemodynamic monitoring in the paediatric intensive care unit, medical and nursing staff assessed cardiac index, systemic vascular resistance index and volume status. Clinical assessment was compared with cardiac index, systemic vascular resistance index and global end diastolic volume index, obtained by femoral artery thermodilution. MEASUREMENTS AND RESULTS: A total of 76 clinical estimations of the three parameters were made in 16 infants and children undergoing biventricular repair of congenital heart lesions. Agreement was poor between clinical and invasive methods of determining all three studied parameters of cardiac performance. Cardiac index was significantly underestimated clinically; mean difference was 0.71 l min(-1) m(-2) (95% range of agreement +/-2.7). Clinical estimates of systemic vascular resistance (weighted kappa=0.15) and volume status (weighted kappa=0.04) showed poor levels of agreement with measured values and were overestimated clinically. There was one complication related to a femoral arterial catheter and one device failure. CONCLUSIONS: Routine clinical assessment of parameters of cardiac performance agreed poorly with invasive determinations of these indices. Management decisions based on inaccurate clinical assessments may be detrimental to patients. Invasive haemodynamic monitoring using femoral artery thermodilution warrants cautious further evaluation as there is little agreement with clinical assessment which is presently standard accepted care in this patient population.