Increased utilization of the hybrid procedure is not associated with improved early survival for newborns with hypoplastic left heart syndrome: a single-centre experience.

OBJECTIVES: The primary objectives were to examine utilization of the Hybrid versus the Norwood procedure for patients with hypoplastic left heart syndrome or variants and the impact on hospital mortality. The Hybrid procedure was 1st used at our institution in 2004. METHODS: Review of all subjects undergoing the Norwood or Hybrid procedure between 1 January 1984 and 31 December 2022. The study period was divided into 8 eras: era 1, 1984-1988; era 2, 1989-1993; era 3, 1994-1998; era 4, 1999-2003; era 5, 2004-2008; era 6, 2009-2014; era 7, 2015-2018 and era 8, 2019-2022. The primary outcome was in-hospital mortality. Mortality rates were computed using standard binomial proportions with 95% confidence intervals. Rates across eras were compared using an ordered logistic regression model with and adjusted using the Tukey-Kramer post-hoc procedure for multiple comparisons. In the risk-modelling phase, logistic regression models were specified and tested. RESULTS: The Norwood procedure was performed in 1899 subjects, and the Hybrid procedure in 82 subjects. Use of the Hybrid procedure increased in each subsequent era, reaching 30% of subjects in era 8. After adjustment for multiple risk factors, use of the Hybrid procedure was significantly and positively associated with hospital mortality. CONCLUSIONS: Despite the increasing use of the Hybrid procedure, overall mortality for the entire cohort has plateaued. After adjustment for risk factors, use of the Hybrid procedure was significantly and positively associated with mortality compared to the Norwood procedure.

Competing risks analysis of time-to-event data for cardiovascular surgeons.

OBJECTIVES: The purpose of this article is to provide thoracic and cardiovascular surgeons with a practical step-by-step strategy to use in collaboration with a biostatistician for implementation of competing risks analysis when analyzing time-to-event data. Patients may have an outside event that precludes the event of interest. Traditional time-to-event analysis incorrectly assumes noninformative censoring in this scenario, which will lead to invalid results and conclusions. METHODS: The steps are (1) to determine whether competing risks analysis is needed, (2) to perform a nonparametric analysis, (3) to perform a model-based analysis, (4) to interpret the results, and (5) to compare to traditional survival analysis methods. We apply our approach to a hypothetical cardiovascular surgery example in determining the hazard of mortality after the stage 3 Fontan operation associated with prematurity among patients with hypoplastic left heart syndrome who had successful completion of Norwood stage 1 while incorporating mortality during the stage 2 bidirectional Glenn procedure as a competing risk. We apply nonparametric, semiparametric, and parametric methods. RESULTS: Although Cox regression establishes prematurity as a significant risk factor of mortality after stage 3 (hazard ratio, 1.26; 95% confidence interval, 1.06-1.50; P = .009), the competing risks analysis with the Fine-Gray model accounting for mortality after stage 2 determines that prematurity is not a significant predictor (hazard ratio, 1.07; 95% confidence interval, 0.90-1.27; P = .467). CONCLUSIONS: This article provides a practical step-by-step approach for making competing risks more accessible for cardiac surgeons collaborating with a biostatistician in analyzing and interpreting time-to-event data.

Thirty years and 1663 consecutive Norwood procedures: Has survival plateaued?

OBJECTIVE: Hypoplastic left heart syndrome is one of the most common and challenging lesions requiring surgical intervention in the neonatal period. The Norwood procedure for hypoplastic left heart syndrome was first reported in 1983. The objective of this study was to describe early outcomes after the Norwood procedure at a single institution over 30 years. METHODS: This retrospective cohort study included all patients with hypoplastic left heart syndrome (and variants) who underwent the Norwood procedure between January 1984 and May 2014 at a single institution. The study period was divided into 6 eras: era 1, 1984 to 1988; era 2, 1989 to 1993; era 3, 1994 to 1998; era 4, 1999 to 2003; era 5, 2004 to 2008; and era 6, 2009 to 2014. The primary outcome was in-hospital mortality after the Norwood procedure. Binomial point estimates complete with 95% confidence intervals (CL0.95) were computed for the entire cohort and by era. RESULTS: During the study period, 1663 infants underwent the Norwood procedure. Overall in-hospital mortality was 25.9% (CL0.95, 23.8-28.0). Mortality by chronologic era was 40.4% (CL0.95, 34.9-45.9), 33.6% (CL0.95, 29.2-37.9), 28.7% (CL0.95, 22.8-34.6), 14.9% (CL0.95, 10.4-19.3), 11.2% (CL0.95, 7.4-15.0), and 15.7% (CL0.95, 10.3-21.1). Survival was improved in eras 4 to 6 compared with eras 1 to 3 (P all < .03). Anomalous pulmonary drainage, moderate to severe atrioventricular valve regurgitation, lower birth weight, earlier era, younger gestational age, genetic anomaly, preterm birth, race other than white or African-American, and lower weight at the Norwood procedure were associated with increased mortality. Mortality was greatest in patients with 3 or more risk factors. In the best-fitting multiple covariate model, anomalous pulmonary venous drainage, gestational age in weeks, genetic anomaly, and race other than white and African American were statistically significant contributors, after adjusting for era. CONCLUSIONS: Survival after the Norwood procedure has plateaued despite improvements in diagnosis, perioperative care, and surgical techniques. Nonmodifiable patient characteristics are important determinants of the risk of mortality.

Outcomes and risk factors associated with tricuspid valve repair in children with hypoplastic left heart syndrome.

OBJECTIVES: Tricuspid valve (TV) competence is important for successful palliation of hypoplastic left heart syndrome (HLHS). We report our experience with TV repair in HLHS patients with a focus on TV and right ventricular (RV) function and associated clinical outcomes. METHODS: From 2002 to 2012, 219 neonates with HLHS underwent the Norwood operation. Thirty patients who underwent TV repair at various stages comprised our current series cohort. Echocardiographic and clinical data were reviewed to determine the effectiveness of TV repair and outcomes of the patients. RESULTS: Thirty patients received TV repair during Norwood (n = 4), Glenn (n = 17) and Fontan (n = 9) operations. Median age at TV repair was 188 days (range 3-1498). Preoperatively, all patients had ≥moderate TV regurgitation and 4 (13%) patients had ≥moderate RV dysfunction. After repair, TV regurgitation was none or trivial (n = 12, 40%), mild (n = 8, 27%), ≥moderate (n = 10, 33%), whereas 10 (33%) had ≥moderate regurgitation at last follow-up; ≥moderate RV dysfunction was present in 5 (17%) patients following TV repair and 10 (33%) patients at last follow-up. Competing risk analysis showed that 10 years following TV repair, 21% of patients had TV reoperation, 18% died or underwent transplantation and 61% were alive without subsequent reoperation. Overall, 10-year survival, transplant-free survival and freedom from second TV reoperation were 89%, 71% and 78%, respectively; ≥moderate RV dysfunction following TV repair was associated with diminished transplant-free survival (P = 0.0277). CONCLUSIONS: Although TV repair is successful in reducing regurgitation in the majority of HLHS patients, outcomes are restricted by limited repair durability with recurrent significant regurgitation in one-third of the patients. RV dysfunction in these patients is progressive and a major determinant of transplant-free survival.

Early results of aortic arch reconstruction and bilateral pulmonary artery banding: modification of the Norwood operation for treatment of hypoplastic left heart syndrome.

BACKGROUND: In the period from 2003 to the end of 2015, 96 Norwood I procedures were performed in the Paediatric Heart Surgery Department in Katowice, Poland, in children with hypoplastic left heart syndrome (HLHS). AIM: This paper presents a retrospective analysis of early surgical results. METHODS: The patients consisted of two groups: group I included 59 children operated on in the years 2003-2012, in whom the stage I Norwood procedure with the Sano modification was performed with the aortic arch reconstructed by use of a ho-mogenous pulmonary artery patch or a bovine pericardial patch. Group II included 37 children after our modification of the Norwood I procedure, in which the aortic arch was reconstructed with an extracellular matrix patch and bilateral pulmonary artery banding was done. RESULTS: Aortic cross-clamping time was significantly shorter in group II (mean 52; range 38-62 min) than in group I (mean 57; range 39-72 min; p < 0.009). Eighteen (30.5%) children in group I and six (16.2%) in group II died. Although this dif-ference did not reach statistical significance (p = 0.12), it suggested that improved outcomes with the modified procedure are possible. The cause of death in group I was significantly more frequently due to massive postoperative bleeding (n = 6; 33.3%) than in group II (n = 1; 16.7%; p = 0.046). CONCLUSIONS: The introduction of this new surgical technique reduced postoperative bleeding rates, shortened the operation time, and might improve the mortality rate in the first-stage surgical treatment of children with HLHS.

Shunt Failure-Risk Factors and Outcomes: An Analysis of The Society of Thoracic Surgeons Congenital Heart Surgery Database.

BACKGROUND: Systemic-to-pulmonary shunt failure is a potentially catastrophic complication. We analyzed a large multicenter clinical registry to describe the prevalence and evaluate risk factors. METHODS: Infants (aged ≤365 days) undergoing shunt operations (systemic artery-to-pulmonary artery or systemic ventricle-to-pulmonary artery) in The Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) from 2010 to 2015 were included. Multivariable logistic regression was used to evaluate risk factors for in-hospital shunt failure. Model covariates included patient characteristics, preoperative factors, procedural factors including shunt type, and center effects. Centers with more than 15% missing data for key covariates were excluded. RESULTS: Shunt operations were performed in 9,172 infants (118 centers). In-hospital shunt failure occurred in 674 (7.3%). In multivariable analysis, risk factors for in-hospital shunt failure included lower weight at operation (odds ratio [OR], 1.35; p = 0.001), preoperative hypercoagulable state (OR, 2.47; p = 0.031), and the presence of any other STS-CHSD preoperative risk factors (OR, 1.24; p = 0.038). Shunt failure was less likely with a systemic ventricle-to-pulmonary artery shunt than a systemic artery-to-pulmonary artery shunt (OR, 0.65; p = 0.020). Neither cardiopulmonary bypass nor single-ventricle diagnosis was a risk factor for shunt failure. Patients with in-hospital shunt failure had significantly higher rates of operative mortality (31.9% vs 11.1%, p < 0.001) and major morbidity (84.4% vs 29.4%, p < 0.001), and longer median postoperative length of stay among survivors (45 vs 22 days, p < 0.001). CONCLUSIONS: In-hospital shunt failure is common, and associated mortality risk is high. These data highlight at-risk patients and procedural cohorts that warrant expectant surveillance and may benefit from enhanced antithrombotic prophylaxis or other management strategies to reduce shunt failure. These findings may inform planning of future clinical trials.

Initial shunt type at the Norwood operation impacts myocardial function in hypoplastic left heart syndrome.

OBJECTIVES: We investigated the impact of initial shunt type, a Blalock-Taussig (BT) shunt versus a right ventricle to pulmonary artery conduit (RV-PA) on myocardial function at different stages of surgical palliation in patients with hypoplastic left heart syndrome (HLHS). METHODS: A population-based cohort of 63 Finnish children with HLHS (BT n = 23, RV-PA n = 40) born between 2003 and 2010 were studied retrospectively by echocardiography prior to Stages 1, 2 and 3 palliation and 0.5-3 years after Stage 3. For comparison of systolic myocardial function, we evaluated the RV fractional area change (FAC), strain, strain rate and mechanical synchrony from the apical 4-chamber view by velocity vector imaging. RESULTS: There were no intergroup differences in demographics during the study period. At baseline, no intergroup differences were detected in RV systolic myocardial function. Before Stage 2, RV FAC was higher ( P = 0.03) in the RV-PA conduit group. At Stage 3, an increase in all systolic myocardial functional parameters was observed in the BT shunt group. After Stage 3, the BT shunt group had better RV systolic function. In multiple regression analysis, the shunt type and the stage of palliation had an impact on myocardial function. CONCLUSIONS: Although patients with HLHS initially palliated with a BT shunt demonstrate lower RV FAC after Stage I, RV FAC improves after Stage 2 with better systolic performance after Stage 3 compared with those initially palliated with an RV-PA conduit.

Hypoplastic left heart syndrome: a novel surgical strategy for small-volume centres?

OBJECTIVES: We describe in a prospective study, a novel surgical technique for the management of hypoplastic left heart syndrome inspired by the hybrid Norwood approach. METHODS: This new neonatal palliation comprises replacement of the patent ductus arteriosus (PDA) and aortic arch plasty with a pulmonary homograft associated with the banding of both pulmonary arteries and atrial septectomy, under cardiopulmonary bypass without aortic clamping and cardioplegia. Initial results led to tightening of the pulmonary artery band from 3.5 mm to 2.5 mm. RESULTS: From July 2014 to May 2016, 15 patients were initially palliated (13 patients with aortic atresia/mitral atresia, 1 with double inlet right ventricle, 1 with tricuspid atresia) at a median age of 5 days (1-8 days) and a median weight of 3.0 kg (2.3-3.9 kg). All but 2 patients were discharged from the hospital: There was 1 early in-hospital death and 1 patient required hospitalization in the intensive care unit until stage 2. There were also 4 interstage deaths. Nine patients underwent Stage 2 and 1 patient is still waiting. Compared to the classic Norwood procedure, early mortality decreased significantly (43.3-6.7%; P = 0.0074) and overall mortality before Stage 2 was halved (61.6-33.3%). Postoperative morbidity was also reduced. CONCLUSIONS: This new surgical palliative approach to hypoplastic left heart syndrome, particularly useable technically, seems to combine the advantages of the hybrid procedure by avoiding cardiac ischaemia and ventriculotomy without the complications of PDA stenting and restrictive atrial septectomy. Although the mortality rate decreased significantly, it remains substantial in small-volume centres, especially in the interstage period.

The Norwood operation: Relative effects of surgeon and institutional volumes on outcomes and resource utilization.

BACKGROUND: Hypoplastic left heart syndrome is the most expensive birth defect managed in the United States, with a 5-year survival rate below 70%. Increasing evidence suggests that hospital volumes are inversely associated with mortality for infants with single ventricles undergoing stage 1 surgical palliation. Our aim was to examine the relative effects of surgeon and institutional volumes on outcomes and resource utilisation for these children. METHODS: A retrospective study was conducted using the Pediatric Health Information System database to examine the effects of the number of procedures performed per surgeon and per centre on mortality, costs, and post-operative length of stay for infants undergoing Risk Adjustment for Congenital Heart Surgery risk category six operations at tertiary-care paediatric hospitals, from 1 January, 2004 to 31 December, 2013. Multivariable modelling was used, adjusting for patient and institutional characteristics. Gaussian kernel densities were constructed to show the relative distributions of the effects of individual institutions and surgeons, before and after adjusting for the number of cases performed. RESULTS: A total of 2880 infants from 35 institutions met the inclusion criteria. Mortality was 15.0%. Median post-operative length of stay was 24 days (IQR 14-41). Median standardized inpatient hospital costs were $156,000 (IQR $108,000-$248,000) in 2013 dollars. In the multivariable analyses, higher institutional volume was inversely associated with mortality (p=0.001), post-operative length of stay (p=0.004), and costs (p=0.001). Surgeon volume was associated with none of the measured outcomes. Neither institutional nor surgeon volumes explained much of the wide variation in outcomes and resource utilization observed between institutions and between surgeons. CONCLUSIONS: Increased institutional - but not surgeon - volumes are associated with reduced mortality, post-operative length of stay, and costs for infants undergoing stage 1 palliation.

Older age at the time of the Norwood procedure is a risk factor for early postoperative mortality†.

OBJECTIVES: The Norwood procedure is commonly used as first-step palliation in children with hypoplastic left heart syndrome or related congenital malformations. In most cases, the operation is carried out during the first week of life. Excessive pulmonary blood flow in univentricular physiology can soon lead to compromised cardiac function and pulmonary hypertension and could have an influence on postoperative outcomes. METHODS: Between 1997 and 2011, 257 Norwood procedures were performed at the Kinderherz-Zentrum Linz. Twenty-seven patients were older than 20 days at the time of the Norwood operation without previous pulmonary artery banding. A retrospective analysis of the two age groups was carried out concerning early mortality, interstage mortality and major events until the bidirectional Glenn operation. RESULTS: Patients older than 20 days had a significantly higher mortality rate before the bidirectional Glenn operation than younger patients (44.4 vs 20.3%; P = 0.002). They also showed a significantly higher need for postoperative inhalative nitric oxide therapy (40.7 vs 14.5%, P = 0.002). Summarized risk for either successful postoperative cardiopulmonary resuscitation (CPR), extracorporeal membrane oxygenation therapy or mortality before the bidirectional Glenn operation was 59.3% in the older age group vs 23.8% in the younger age group (P < 0.001). CONCLUSIONS: Age older than 20 days seems to be an independent risk factor for early postoperative mortality and fatal events after the Norwood procedure. Long-persisting excessive pulmonary blood flow and preoperative cardiac decompensation can be the reason for postoperative lethal pulmonary hypertensive crisis and compromised ventricular function.

Hybrid versus Norwood strategies for single-ventricle palliation.

BACKGROUND: Hybrid and Norwood strategies differ substantially in terms of stage II palliative procedures. We sought to compare these strategies with an emphasis on survival and reintervention after stage II and subsequent Fontan completion. METHODS AND RESULTS: Of 110 neonates with functionally single-ventricle physiology who underwent stage I palliation between 2004 and 2010, 75 (69%) infants (Norwood, n=43; hybrid, n=32) who subsequently underwent stage II palliation were studied. Survival and reintervention rates after stage II palliation, anatomic and physiologic variables at pre-Fontan assessment, and Fontan outcomes were compared between the groups. Predictors for reintervention were analyzed. Freedom from death/transplant after stage II palliation was equivalent between the groups (Norwood, 80.4% versus hybrid, 85.6% at 3 years, P=0.66). Hybrid patients had a higher pulmonary artery (PA) reintervention rate (P=0.003) and lower Nakata index at pre-Fontan evaluation (P=0.015). Aortic arch and atrioventricular valve reinterventions were not different between the groups. Ventricular end-diastolic pressure, mean PA pressure, and ventricular function were equivalent at pre-Fontan assessment. There were no deaths after Fontan completion in either group (Norwood, n=25, hybrid, n=14). CONCLUSIONS: Survival after stage II palliation and subsequent Fontan completion is equivalent between the groups. The hybrid group had a higher PA reintervention rate and smaller PA size. Both strategies achieved adequate physiology for Fontan completion. Evolution of the hybrid strategy requires refinement to provide optimal PA growth.

Hemodynamic simulation for surgical treatment of congenital heart disease.

Numerical analysis of cardiovascular flow is one of several methods of use for the quantitative evaluation of patient-specific treatments. However, due to the complexity of vascular geometry and flow conditions, the cardiovascular flow simulation continues to be a challenging project. As the flow at the peak of systolic heart beat displayed full turbulence, the congenital heart treatments, Norwood and TCPC procedure, were investigated through the use of computational hemodynamic technology, in the present study. On the other hand, at diastolic period, the flow fell to an almost sedentary state. This indicated that the cardiovascular flow experienced a strange transition of flow from systolic peak to diastole. Thus, in order to accurately simulate this transitional flow, a very small time step was applied in the k - ε turbulent model calculation. Energy losses (EL), local pressure and wall shear stress were analyzed to estimate the result of clinical treatments. It was found that the value of EL, including the influence of respiration, was 1.5 times higher than the value of EL, disregarding respiratory influences. These results indicated that the hemodynamic outcomes of TCPC treatment are noticeably influenced by respiration. The effect of respiration plays an important role in estimating the results of TCPC treatment and thus should be included as one of the important conditions of computational hemodynamic analysis.

Pathology of the aortic arch in hypoplastic left heart syndrome: surgical implications.

Aortic arch reconstruction plays an important role in the success of the Norwood procedure (NP) for hypoplastic left heart syndrome (HLHS). This study investigated the cardiac specimens to determine the etiology of distal aortic arch obstruction after the NP for HLHS and to locate coarctation of the aorta in HLHS untreated by surgery. This study examined 17 cardiac specimens: 9 that had NP and 8 not treated by surgery. The findings after NP showed frequent failure to resect the coarctation segment completely and failure to extend the augmentation patch into the descending aorta. Five (62.5%) of the eight hearts not treated by surgery had significant periductal coarctation of the aorta. After NP for nine patients, three (33%) had residual coarctation of the aorta. To minimize the risk of recurrent or persistent aortic arch obstruction after NP and to improve the long- and short-term outcome, the ductal tissue and the coarctation segment encircling the aortic lumen should be resected. The distal wall incision should be extended at least 5 mm beyond the distal aspect of the ductal tissue. These steps could avoid major aortic arch obstruction, promote growth of the native aortic tissue, and avoid ventricular dysfunction.