Single-ventricle palliation for high-risk neonates: the emergence of an alternative hybrid stage I strategy

Use of Hybrid Stage I to Stratify Between Single Ventricle Palliation and Biventricular Repair

Background: Hybrid stage I palliation (HS1P) has been utilized for patients with single ventricle (SV) congenital heart disease (CHD). To date, reports on the use of HS1P for other indications including biventricular (BiV) CHD have been limited. Methods: We performed a single-center retrospective cohort study of patients who underwent HS1P with an anticipated physiologic outcome of BiV repair, or with an undetermined SV versus BiV outcome. Patient characteristics and outcomes from birth through definitive repair or palliation were collected and reported with descriptive statistics. Results: Nineteen patients underwent HS1P with anticipated BiV repair. Extracardiac and intracardiac risk factors (ICRF) were common. Ultimately, 13 (68%) patients underwent BiV repair, 1 (5%) underwent SV palliation, and 5 (26%) died prior to further palliation or repair. Resolution of ICRF tracked with BiV outcome (6/6, 100%), persistence of ICRF tracked with SV outcome or death (3/3, 100%). Twenty patients underwent HS1P with an undetermined outcome. Ultimately, 13 (65%) underwent BiV repair, 6 (30%) underwent SV palliation, and 1 (5%) underwent transplant. There were no deaths. Intracardiac risk factors were present in 15 of 20 patients (75%); BiV repair only occurred when all ICRF resolved (67%). Post-HS1P complications and reinterventions occurred frequently in both groups, through all phases of care. Conclusions: Hybrid stage 1 palliation can be used to defer BiV repair and to delay decision between SV palliation and BiV repair. Resolution of ICRF was associated with ultimate outcome. In this high-risk group, complications are common, and mortality especially in the marginal BiV patient is high.

Comparison of Morbidity and Mortality Outcomes between Hybrid Palliation and Norwood Palliation Procedures for Hypoplastic Left Heart Syndrome: Meta-Analysis and Systematic Review

Background/Objectives: Hybrid palliation (HP) procedures for hypoplastic left heart syndrome (HLHS) are increasing. Our objective was to compare mortality and morbidity following HP and NP (Norwood palliation) procedures. Methods: Systematic review and meta-analysis of HLHS patients of peer-reviewed literature between 2000 and 2023. Mortality and/or heart transplantation in HP versus NP in the neonatal period, interstage period, and at 1, 3 and 5 years of age, and morbidity including completion of Stage II and Stage III palliation, unexpected interventions, pulmonary artery pressures, right ventricle function, neurodevelopmental outcomes and length of hospital stay were evaluated. Results: Twenty-one (meta-analysis: 16; qualitative synthesis: 5) studies evaluating 1182 HLHS patients included. HP patients had higher interstage mortality (RR = 1.61; 95% CI: 1.10-2.33; p = 0.01) and 1-year mortality (RR = 1.22; 95% CI: 1.03-1.43; p = 0.02) compared to NP patients without differences in 3- and 5-years mortality. HP procedure in high-risk HLHS patients had lower mortality (RR = 0.48; 95% CI: 0.27-0.87; p = 0.01) only in the neonatal period. HP patients underwent fewer Stage II (RR = 0.90; 95% CI: 0.81-1.00; p = 0.05) and Stage III palliation (RR = 0.78; 95% CI: 0.69-0.90; p < 0.01), had more unplanned interventions (RR = 3.38; 95% CI: 2.04-5.59; p < 0.01), and longer hospital stay after Stage I palliation (weighted mean difference = 12.88; 95% CI: 1.15-24.62; p = 0.03) compared to NP patients. Conclusions: Our study reveals that HP, compared to NP for HLHS, is associated with increased morbidity risk without an improved survival rate.

Hybrid Interventions in Congenital Heart Disease

Hybrid interventions in congenital heart disease (CHD) embody the inherent collaboration between congenital interventional cardiology and cardiothoracic surgery. Hybrid approaches to complex and common lesions provide the opportunity to circumvent the limitations of patient size, vascular access, severity of illness, and anatomy that would otherwise be prohibitive to surgical and percutaneous techniques alone. This review describes several important hybrid approaches to interventions in CHD.

Cardiac Rhabdomyomas Presenting with Critical Cardiac Obstruction in Neonates and Infants: Treatment Strategies and Outcome, A Single-Center Experience

Cardiac rhabdomyomas are the most common benign pediatric heart tumor in infancy, which are commonly associated with tuberous sclerosis complex (TSC). Most rhabdomyomas are asymptomatic and spontaneously regress over time. However, some cases especially in neonates or small infants can present with hemodynamic instability. Surgical resection of the tumor, which has been the gold standard in alleviating obstruction, is not always possible and may be associated with significant morbidity and mortality. Recently, mammalian target of rapamycin inhibitors (mTORi) have been shown to be safe and effective in the treatment of TSC. We present the outcomes of neonates and an infant who received treatment for symptomatic rhabdomyomas at a tertiary cardiology center. Medical records were reviewed to obtain clinical, demographic, and outcome data. Six patients received interventions for symptomatic rhabdomyomas, median age at presentation was 1 day old (range from 1 to 121 days old), and 67% of the patients had a pathogenic mutation in TSC gene. One patient underwent surgical resection of solitary tumor at right ventricular outflow tract (RVOT) successfully. In the four patients with left ventricular outflow tract (LVOT) obstruction, two patients received combined therapy of surgical debulking of LVOT tumor, Stage I palliation procedure, and mTORi and two patients received mTORi therapy. One patient with RVOT obstruction underwent ductal stenting and received synergistic mTORi. Four of the five patients had good response to mTORi demonstrated by the rapid regression of rhabdomyoma size. 83% of patients are still alive at their latest follow-up, at two to eight years of age. One patient died on day 17 post-LVOT tumor resection and Hybrid stage one due to failure of hemostasis, in the background of familial factor VII deficiency. Treatment of symptomatic rhabdomyoma requires individualized treatment strategy based on the underlying pathophysiology, with involvement of multidisciplinary teams. mTORi is effective and safe in inducing rapid regression of rhabdomyomas. A standardized mTORi prescription and monitoring guide will ensure medication safety in neonates and infants with symptomatic cardiac rhabdomyoma. Although the majority of tumors responded to mTORi, some prove to be resistant. Further studies are warranted, ideally involving multiple international centers with a larger number of patients.

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.

Hybrid stage 1 palliation for HLHS: the experience of a tertiary center in a developing country

Background

Hypoplastic left heart syndrome (HLHS) accounts for 2.6% of congenital heart disease and is an invariably fatal cardiac anomaly if left untreated. Approximately 33,750 babies are born annually with HLHS in developing countries. Unfortunately, the majority will not survive due to the scarcity of resources and the limited availability of surgical management.

Aim

To describe and analyze our experience with the hybrid approach in the management of HLHS in a developing country.

Methods

We performed a retrospective single-center study involving all neonates born with HLHS over five years at the Children's Heart Center at the American University of Beirut. The medical records of patients who underwent the hybrid stage 1 palliation were reviewed, and data related to baseline characteristics, procedure details and outcomes were collected to describe the experience at a tertiary care center in a developing country.

Results

A total of 18 patients were diagnosed with HLHS over a five-year period at our institution, with male to female ratio of 1:1. Of those, eight patients underwent the hybrid stage I procedure. The mean weight at the time of the procedure was 3.3 ± 0.3 kg with an average age of 6.4 ± 4 days. The mean hospital length of stay was 27.25 days, with an interquartile range of 33 days. The cohort's follow-up duration averaged 5.9 ± 3.5 years. The surgical mortality was zero. Only one mortality was recorded during the interstage period between stage I and II and was attributed to sepsis. Notably, all surviving patients maintained preserved and satisfactory cardiac function with good clinical status.

Conclusion

Our limited experience underscores the potential of developing countries with proper foundations to adopt the hybrid procedure for HLHS, yielding outcomes on par with those observed in developed countries. This demonstrates the viability of establishing a more balanced global landscape for children with congenital heart disease.

Mortality and Heart Transplantation After Hybrid Palliation of Hypoplastic Left Heart Syndrome: A Systematic Review and Meta-Analysis

BACKGROUND

Newborns with hypoplastic left heart syndrome (HLHS) who are considered at increased risk for death following Norwood/Sano surgery often undergo hybrid palliation (HP) as initial surgery. We aimed to compile the HP experience in HLHS and its variants and assess the rates of, and risk factors for, death and heart transplantation.

METHODS

CINAHL, CINAHL PLUS, PubMed/MEDLINE, and SCOPUS were systematically searched for HP outcome studies of death or heart transplantation in HLHS between 1998 and 2022. Pooled incidence was estimated, and potential risk factors were identified using random-effects meta-analysis and reconstructed time-to-event data from Kaplan-Meier curves.

RESULTS

Thirty-three publications were included in our review. Overall, of 1,162 patients 417 died and 57 underwent heart transplantation, resulting in a combined outcome of 40.7%, (474/1,162). There was a trend toward decreasing mortality risk across the stages of palliation. Pooled mortality between HP and comprehensive stage 2 palliation was 25%, after stage 2 up to Fontan palliation was 16%, and 6% post-Fontan. The incidence of death or heart transplantation was higher in high-risk patients-43% died and 10% received heart transplantation.

CONCLUSION

Our systematic review and meta-analysis found high rates of death or heart transplantation in HP of HLHS patients between HP and Fontan surgeries. All patients should be closely followed during the initial interstage period, which is associated with the highest hazard. Prospective studies on appropriate patient selection, indications, and / or alternatives, as well as refining HP strategies for managing newborns with HLHS are needed to improve outcomes.

From Surgical to Total Transcatheter Stage I Palliation: Exploring Evidence and Perspectives

Neonates with single ventricle physiology and ductal-dependent systemic circulation, such as those with hypoplastic left heart syndrome, undergo palliation in the first days of life. Over the past decades, variations on the traditional Stage 1 palliation, also known as Norwood operation, have emerged. These include the hybrid palliation and the total transcatheter approach. Here, we review the current evidence and data on different Stage 1 approaches, with a focus on their advantages, challenges, and future perspectives. Overall, although controversy remains regarding the superiority or inferiority of one approach to another, outcomes after the Norwood and the hybrid palliation have improved over time. However, both procedures still represent high-risk approaches that entail exposure to sternotomy, surgery, and potential cardiopulmonary bypass. The total transcatheter Stage 1 palliation spares patients the surgical and cardiopulmonary bypass insults and has proven to be an effective strategy to bridge even high-risk infants to a later palliative surgery, complete repair, or transplant. As the most recently proposed approach, data are still limited but promising. Future studies will be needed to better define the advantages, challenges, outcomes, and overall potential of this novel approach.

Transcatheter Palliation With Pulmonary Artery Flow Restrictors in Neonates With Congenital Heart Disease: Feasibility, Outcomes, and Comparison With a Historical Hybrid Stage 1 Cohort

BACKGROUND

Neonates with complex congenital heart disease and pulmonary overcirculation have been historically treated surgically. However, subcohorts may benefit from less invasive procedures. Data on transcatheter palliation are limited.

METHODS

We present our experience with pulmonary flow restrictors (PFRs) for palliation of neonates with congenital heart disease, including procedural feasibility, technical details, and outcomes. We then compared our subcohort of high-risk single ventricle neonates palliated with PFRs with a similar historical cohort who underwent a hybrid Stage 1. Cox regression was used to evaluate the association between palliation strategy and 6-month mortality.

RESULTS

From 2021 to 2023, 17 patients (median age, 4 days; interquartile range [IQR], 2-8; median weight, 2.5 kilograms [IQR, 2.1-3.3]) underwent a PFR procedure; 15 (88%) had single ventricle physiology; 15 (88%) were high-risk surgical candidates. All procedures were technically successful. At a median follow-up of 6.2 months (IQR, 4.0-10.8), 13 patients (76%) were successfully bridged to surgery (median time since PFR procedure, 2.6 months [IQR, 1.1-4.4]; median weight, 4.9 kilograms [IQR, 3.4-5.8]). Pulmonary arteries grew adequately for age, and devices were easily removed without complications. The all-cause mortality rate before target surgery was 24% (n=4). Compared with the historical hybrid stage 1 cohort (n=23), after adjustment for main confounding (age, weight, intact/severely restrictive atrial septum or left ventricle to coronary fistulae), the PFR procedure was associated with a significantly lower all-cause 6-month mortality risk (adjusted hazard ratio, 0.26 [95% CI, 0.08-0.82]).

CONCLUSIONS

Transcatheter palliation with PFR is feasible, safe, and represents an effective strategy for bridging high-risk neonates with congenital heart disease to surgical palliation, complete repair, or transplant while allowing for clinical stabilization and somatic growth.

Hybrid palliation versus nonhybrid management for a multi-institutional cohort of infants with critical left heart obstruction

OBJECTIVE

To compare patient characteristics and overall survival for infants with critical left heart obstruction after hybrid palliation (bilateral pulmonary artery banding with or without ductal stenting) versus nonhybrid management (eg, Norwood, primary transplantation, biventricular repair, or transcatheter/surgical aortic valvotomy).

METHODS

From 2005 to 2019, 1045 infants in the Congenital Heart Surgeons' Society critical left heart obstruction cohort underwent interventions across 28 institutions. Using a balancing score propensity analysis, 214 infants who underwent hybrid palliation and 831 infants who underwent nonhybrid management were proportionately matched regarding variables significantly associated with mortality and variables noted to significantly differ between groups. Overall survival between the 2 groups was adjusted by applying balancing scores to nonparametric estimates.

RESULTS

Compared with the nonhybrid management group, infants who underwent hybrid palliation had lower birth weight, smaller gestational age, and higher prevalence of in-utero interventions, noncardiac comorbidities, preoperative mechanical ventilation, absent interatrial communication, and moderate or severe mitral valve stenosis (all P values < .03). Unadjusted 12-year survival after hybrid palliation and nonhybrid management, was 55% versus 69%, respectively. After matching, 12-year survival after hybrid palliation versus nonhybrid management was 58% versus 63%, respectively (P = .37). Among matched infants born weighing <2.5 kg, 2-year survival after hybrid palliation versus nonhybrid management was 37% versus 51%, respectively (P = .22).

CONCLUSIONS

Infants born with critical left heart obstruction who undergo hybrid palliation have more high-risk characteristics and anatomy versus infants who undergo nonhybrid management. Nonetheless, after adjustment, there was no significant difference in 12-year survival after hybrid palliation versus nonhybrid management. Mortality remains high, and hybrid palliation confers no survival advantage, even for lower-birth-weight infants.

Outcomes After Hybrid Palliation for Infants With Critical Left Heart Obstruction

BACKGROUND

Hybrid palliation (bilateral pulmonary artery banding with or without ductal stenting) is an initial management strategy for infants with critical left heart obstruction and serves as palliation until subsequent operations are pursued.

OBJECTIVES

This study sought to determine patient characteristics and factors associated with subsequent outcomes for infants who underwent hybrid palliation.

METHODS

From 2005 to 2019, 214 of 1,236 prospectively enrolled infants within the Congenital Heart Surgeons' Society's critical left heart obstruction cohort underwent hybrid palliation across 24 institutions. Multivariable hazard modeling with competing risk methodology was performed to determine risk and factors associated with outcomes of biventricular repair, Fontan procedure, transplantation, or death.

RESULTS

Preoperative comorbidities (eg, prematurity, low birth weight, genetic syndrome) were identified in 70% of infants (150 of 214). Median follow-up was 7 years, ranging up to 17 years. Overall 12-year survival was 55%. At 5 years after hybrid palliation, 9% had biventricular repair, 36% had Fontan procedure, 12% had transplantation, 35% died without surgical endpoints, and 8% were alive without an endpoint. Factors associated with transplantation were absence of ductal stent, older age, absent interatrial communication, smaller aortic root size, larger tricuspid valve area z-score, and larger left ventricular volume. Factors associated with death were low birth weight, concomitant genetic syndrome, cardiopulmonary bypass use during hybrid palliation, moderate to severe tricuspid valve regurgitation, and smaller ascending aortic size.

CONCLUSIONS

Mortality remains high after hybrid palliation for infants with critical left heart obstruction. Nonetheless, hybrid palliation may facilitate biventricular repair for some infants and for others may serve as stabilization for intended functional univentricular palliation or primary transplantation.

Cell-based therapy to boost right ventricular function and cardiovascular performance in hypoplastic left heart syndrome: Current approaches and future directions

Congenital heart disease remains one of the most frequently diagnosed congenital diseases of the newborn, with hypoplastic left heart syndrome (HLHS) being considered one of the most severe. This univentricular defect was uniformly fatal until the introduction, 40 years ago, of a complex surgical palliation consisting of multiple staged procedures spanning the first 4 years of the child's life. While survival has improved substantially, particularly in experienced centers, ventricular failure requiring heart transplant and a number of associated morbidities remain ongoing clinical challenges for these patients. Cell-based therapies aimed at boosting ventricular performance are under clinical evaluation as a novel intervention to decrease morbidity associated with surgical palliation. In this review, we will examine the current burden of HLHS and current modalities for treatment, discuss various cells therapies as an intervention while delineating challenges and future directions for this therapy for HLHS and other congenital heart diseases.

In-Silico and In-Vitro Analysis of the Novel Hybrid Comprehensive Stage II Operation for Single Ventricle Circulation

Single ventricle (SV) anomalies account for one-fourth of all congenital heart disease cases. The existing palliative treatment for this anomaly achieves a survival rate of only 50%. To reduce the trauma associated with surgical management, the hybrid comprehensive stage II (HCSII) operation was designed as an alternative for a select subset of SV patients with the adequate antegrade aortic flow. This study aims to provide better insight into the hemodynamics of HCSII patients utilizing a multiscale Computational Fluid Dynamics (CFD) model and a mock flow loop (MFL). Both 3D-0D loosely coupled CFD and MFL models have been tuned to match baseline hemodynamic parameters obtained from patient-specific catheterization data. The hemodynamic findings from clinical data closely match the in-vitro and in-silico measurements and show a strong correlation (r = 0.9). The geometrical modification applied to the models had little effect on the oxygen delivery. Similarly, the particle residence time study reveals that particles injected in the main pulmonary artery (MPA) have successfully ejected within one cardiac cycle, and no pathological flows were observed.

The ductus arteriosus in neonates with critical congenital heart disease

The ductus arteriosus (DA) has a paradoxical biological role in neonates with congenital heart disease (CHD) and can present with significant management challenges. Critical congenital cardiac lesions rely on the patency of the DA to provide either systemic or pulmonary blood flow. A patent DA (PDA) that remains open can also have adverse consequences depending on the degree of systemic to-pulmonary shunting and volume of ductal steal. As such, the presence of a PDA may pose a challenge in the medical management and timing of surgical repair. In this perspective article, we provide an understanding of the role of the DA in the circulatory system in neonates with CHD and discuss traditional and emerging approaches to support the pulmonary and systemic circulations with manipulation of the DA.

Computational fluid dynamics investigation of the novel hybrid comprehensive stage II operation

Background

The hybrid comprehensive stage 2 (HCS2) procedure is a novel palliative operation applicable to a select subset of single ventricle patients with adequate native antegrade aortic flow to the upper body. Flow to the descending aorta, through the pulmonary outlet and ductal arch, is influenced by a stented intrapulmonary baffle connecting the branch pulmonary arteries. We used computational fluid dynamics (CFD) to elucidate the hemodynamic characteristics of this reconstruction.

Methods

We used multiscale CFD analysis of a synthetic, patient-derived HCS2 anatomic configuration with unsteady laminar flow conditions and a non-Newtonian blood model to quantify the resultant hemodynamics. The 3-dimensional CFD model was coupled to a 0-dimensional lumped parameter model of the peripheral circulation to determine the required boundary conditions.

Results

For the specific anatomy studied, the intrapulmonary baffle did not obstruct flow from the pulmonary trunk to ductal arch as long as the distance between the anterior pulmonary artery wall and baffle wall exceeded ∼7 mm. Vortex shedding off of the baffle wall did not develop, because of the short distance to the ductal arch. The stented baffle experienced significantly uneven "inward" loading from the systemic side. Pulmonary outlet flow separation distal to the baffle produced a low-speed recirculation region.

Conclusions

Hemodynamic patterns in this complex anatomy are generally favorable. Low flow recirculation could be mitigated by preoperative shape optimization. Calculated inward stresses on the pulmonary baffle can be used in the future to study baffle stent deformation, which is expected to be small.

Percutaneous Stage 1 Palliation for Hypoplastic Left Heart Syndrome

Surgical palliation for hypoplastic left heart syndrome (HLHS) still carries significant morbidity and mortality in neonates. We previously described a percutaneous stage-I palliation (PS1P) in a swine experiment. This report is the first human application of the PS1P for HLHS in the United States. The procedure is performed via a 4-French sheath in the femoral vein. Bilateral pulmonary flow restrictors are implanted in the proximal branch pulmonary arteries and a stent within the ductus arteriosus. PS1P could postpone surgical repair beyond the neonatal period. It offers a simple, less invasive alternative to currently available surgeries for newborns with HLHS.

Indications and results for hybrid interventions in patients with congenital heart disease

A hybrid therapy or procedure is a new treatment modality that develops by combining therapies from different subspecialties. In congenital heart disease, a growing number of such procedures have been described in recent decades, as a result of increasing collaboration between surgeons and interventionalists. The ideas behind these therapies include enabling the performance of procedures of different complexity in a less invasive manner, shortening procedural times, avoiding cardiopulmonary bypass, facilitating vascular access and decreasing the number of complications associated with more invasive approaches. Over the years, hybrid therapy has gained a place as a widely accepted therapeutic option for the management of several conditions in high-risk patients with congenital heart disease.

The Evolution of Therapeutic Strategies: Niche Apportionment for Hybrid Palliation

Hybrid palliation, the concept to stabilize univentricular circulation with bilateral pulmonary artery banding and maintenance of ductal patency, has significantly widened the therapeutic spectrum for patients with single-ventricle malformations or borderline hypoplasia. The concept has already been a part of early attempts to improve outcome in hypoplastic left heart syndrome but has not attracted much attention initially. Technical refinement and expertise have led to results that ultimately allowed the palliative strategy to gain traction and to be selectively adopted. By now, we have gained almost 2 decades of experience, and as much as hybrid palliation has changed our approach to single-ventricle management, new strategies and indications have been formed by this experience. We therefore review concepts and patterns of use of hybrid palliation as well as benefits and challenges of the respective pathways to highlight the current status of the hybrid procedure.

Impact of Hybrid Stage 1 Palliation for Hypoplastic Left Heart Syndrome: Histopathological Findings

The purpose of the study is to analyze the impact of hybrid stage 1 palliation on right ventricular myocardial pathology in hypoplastic left heart syndrome. Sufficient amount of right ventricular biopsies could be obtained from 16 of 32 patients who underwent Norwood operation between 2007 and 2013. Histopathological findings of right ventricle in patients who underwent primary Norwood operation (primary group, n = 5), patients with aortic atresia (HS1P AA group, n = 6) or aortic stenosis (HS1P AS group, n = 5) who underwent staged Norwood palliation following hybrid stage 1 palliation were compared. To eliminate the influence of right ventricular pressure afterload, right ventricular biopsies were obtained from patients with truncus arteriosus communis (TAC group, n = 6) at total correction. The percentage of myocardial fibrosis was significantly higher in both HS1P groups than in TAC group; moreover, it was significantly higher in HS1P AA group than in primary group. Capillary vascular density was significantly lower in all hypoplastic left heart syndrome groups than in TAC group. At the sub-endocardial layer, collagen type I/III ratios were higher in HS1P AA group than in other hypoplastic left heart syndrome groups. The proportions of N-cadherin immunolocalized to myocyte termini were lower in all hypoplastic left heart syndrome groups than in TAC group. Right ventricle in hypoplastic left heart syndrome showed more significant ischemic change and myocardial immaturity than that in truncus arteriosus communis. Hybrid stage 1 palliation for aortic atresia would be a risk factor for further right ventricular myocardial ischemia.

Patient-specific multiscale computational fluid dynamics assessment of embolization rates in the hybrid Norwood: effects of size and placement of the reverse Blalock-Taussig shunt

The hybrid Norwood operation is performed to treat hypoplastic left heart syndrome. Distal arch obstruction may compromise flow to the brain. In a variant of this procedure, a synthetic graft (reverse Blalock-Taussig shunt) is placed between the pulmonary trunk and innominate artery to improve upper torso blood flow. Thrombi originating in the graft may embolize to the brain. In this study, we used computational fluid dynamics and particle tracking to investigate the patterns of particle embolization as a function of the anatomic position of the reverse Blalock-Taussig shunt. The degree of distal arch obstruction and position of particle origin influence embolization probabilities to the cerebral arteries. Cerebral embolization probabilities can be reduced by as much as 20% by optimizing graft position, for a given arch geometry, degree of distal arch obstruction, and particle origin. There is a tradeoff, however, between cerebral pulmonary and coronary embolization probabilities.

Hybrid Strategy for Neonates With Ductal-Dependent Systemic Circulation at High Risk for Norwood

BACKGROUND

Hypoplastic left heart syndrome and other cardiac lesions with ductal-dependent systemic circulation continue to be challenging to manage, especially in high-risk (HR) populations (those with prematurity, multiple congenital anomalies, moderate to severe tricuspid regurgitation, hemodynamic instability, intact atrial septum).

METHODS

A retrospective study on our institution's experience implementing a hybrid strategy as initial palliation in HR patients with ductal-dependent systemic circulation in HR patients undergoing Norwood versus hybrid procedure. From July 2004 to May 2008, 16 HR patients underwent stage I Norwood procedure. After implementation of a hybrid strategy in 2008, 24 HR patients underwent hybrid procedure from May 2008 to November 2015.

RESULTS

There was no difference in gestational age, age at procedure, or hospital length of stay. The HR Hybrid group had lower mean weight (2.6 kg vs 3.1 kg, p = 0.026). Thirty-day mortality was lower in the HR Hybrid group (4% vs 31%, p = 0.019), although there was no difference in interstage mortality (17% vs 9%, p = 0.396). Catheter-based reintervention was more prevalent in the HR Hybrid group, but did not have a negative impact on survival. One-year transplant-free survival was similar (p = 0.416). HR Hybrid patients weighing less than 2.6 kg had higher overall survival (83% vs 25%, p = 0.013), as did patients who were premature (70% vs 0%, p = 0.003).

CONCLUSIONS

In high-risk patients, the hybrid procedure appears to have lower 30-day mortality and may have a survival benefit in premature patients and those less than 2.6 kg. Long-term attrition in this high-risk population is ongoing regardless of early strategy.

Innovative interventional catheterization techniques for congenital heart disease

Since 1929, when the first cardiac catheterization was safely performed in a human by Dr. Werner Forssmann (on himself), there has been a rapid progression of cardiac catheterization techniques and technologies. Today, these advances allow us to treat a wide variety of patients with congenital heart disease using minimally invasive techniques; from fetus to infants to adults, and from simple to complex congenital cardiac lesions. In this article, we will explore some of the exciting advances in cardiac catheterization for the treatment of congenital heart disease, including transcatheter valve implantation, hybrid procedures, biodegradable technologies, and magnetic resonance imaging (MRI)-guided catheterization. Additionally, we will discuss innovations in imaging in the catheterization laboratory, including 3D rotational angiography (3DRA), fusion imaging, and 3D printing, which help to make innovative interventional approaches possible.

Cerebral Blood Flow Following Hybrid Stage I Palliation in Infants with Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) palliation may result in altered cerebral blood flow with subsequent neurodevelopmental implications. The purpose of the study was to assess blood flow in the middle cerebral artery (MCA) and investigate the relationship with early neurodevelopmental outcomes in infants with HLHS after hybrid stage I. Transcranial Doppler (TCD) was performed to obtain peak systolic, end-diastolic, and mean velocities, as well as pulsatility index of the MCA in infants with HLHS (n = 18) at baseline and at 2, 4, and 6 months of age. Developmental assessment was performed at 6 months of age. Results of TCD and development were compared to healthy control subjects (n = 6) and normative data. Overall, peak systolic velocity (p = 0.0031), end-diastolic velocity (p < 0.0001), and mean velocity (p < 0.0001) were significantly lower and pulsatility index (p = 0.0011) significantly higher in the HLHS group compared to the control group. A significant increase in change over time was noted for peak systolic velocity (p < 0.0016) and mean velocity (p < 0.0046). There was no significant correlation between TCD variables and development scores. TCD values in 5-6 months old infants with HLHS who undergo hybrid stage I palliation had consistently lower blood flow velocities than control infants; however, pulsatility index was slightly higher. No correlation between TCD measurements and measures of cognitive, language, and motor skills were noted.

Recent advances in pediatric interventional cardiology

During the last 10 years, there have been major technological achievements in pediatric interventional cardiology. In addition, there have been several advances in cardiac imaging, especially in 3-dimensional imaging of echocardiography, computed tomography, magnetic resonance imaging, and cineangiography. Therefore, more types of congenital heart diseases can be treated in the cardiac catheter laboratory today than ever before. Furthermore, lesions previously considered resistant to interventional therapies can now be managed with high success rates. The hybrid approach has enabled the overcoming of limitations inherent to percutaneous access, expanding the application of endovascular therapies as adjunct to surgical interventions to improve patient outcomes and minimize invasiveness. Percutaneous pulmonary valve implantation has become a successful alternative therapy. However, most of the current recommendations about pediatric cardiac interventions (including class I recommendations) refer to off-label use of devices, because it is difficult to study the safety and efficacy of catheterization and transcatheter therapy in pediatric cardiac patients. This difficulty arises from the challenge of identifying a control population and the relatively small number of pediatric patients with congenital heart disease. Nevertheless, the pediatric interventional cardiology community has continued to develop less invasive solutions for congenital heart defects to minimize the need for open heart surgery and optimize overall outcomes. In this review, various interventional procedures in patients with congenital heart disease are explored.

Ventricular function and vascular dimensions after Norwood and hybrid palliation of hypoplastic left heart syndrome

Objective

Norwood and hybrid procedure are two options available for initial palliation of patients with hypoplastic left heart syndrome (HLHS). Our study aimed to assess potential differences in right ventricular (RV) function and pulmonary artery dimensions using cardiac magnetic resonance (CMR) in survivors with HLHS.

Methods

42 Norwood (mean age 2.4±0.8) and 44 hybrid (mean age 2.0±1.0 years) patients were evaluated by CMR after stage II palliation prior to planned Fontan completion. Initial stage I Norwood procedure was performed using a modified Blalock-Taussig shunt, while the hybrid procedure consisted of bilateral pulmonary artery banding and arterial duct stenting. Need for reinterventions and subsequent outcomes were also assessed.

Results

Norwood patients had larger RV end-diastolic dimensions (91±23 vs 80±31 mL/m2, p=0.004) and lower heart rate (90±15 vs 102±13, p<0.001) than hybrid patients. Both Norwood and hybrid patients showed preserved global RV pump function (59±9 vs 59%±10%, p=0.91), while RV strain, strain rate and intraventricular synchrony were superior in the Norwood group. Pulmonary artery size was reduced (lower lobe index 135±74 vs 161±62 mm2/m2, p=0.02), and reintervention rate was significantly higher in the hybrid group whereas subsequent outcome did not differ significantly (p=0.24).

Conclusions

Norwood and hybrid strategy were associated with equivalent and preserved global RV pump function while development of the pulmonary arteries and reintervention rate were superior using the Norwood approach. Impaired RV myocardial deformation as a potential marker of early RV dysfunction in the hybrid group may have a negative long-term impact in this population.

Popular Hybrid Congenital Heart Procedures without Cardiopulmonary Bypass

As surgical and catheter interventions advance, patients with congenital heart disease are now offered alternative treatment options that cater to their individual needs. Furthermore, collaboration between interventional cardiologists and cardiac surgeons have led to the development of hybrid procedures, using the best techniques of each respective field to treat these complex cardiac entities from initial treatment in the pediatric patient to repeat intervention in the adult. We present a review of the increased popularity and trend in hybrid procedures in congenital heart disease without the use of cardiopulmonary bypass.

Hybrid Stage I Procedure as Initial Palliation for Neonate With Hypoplastic Left Heart Syndrome and Right Congenital Diaphragmatic Hernia

During the past decade, a hybrid procedure has emerged and dramatically evolved as an alternative stage I palliation to the conventional Norwood procedure in neonates with hypoplastic left heart syndrome (HLHS). The hybrid approach avoids the need for cardiopulmonary bypass (CPB) utilizing stenting of the arterial duct and bilateral pulmonary artery banding. Cerebral and coronary perfusion pressure is maintained, and the pulmonary vasculature is protected from higher systemic pressure. Elimination of risks associated with CPB gains vital time to stabilize the patient and correct coexisting noncardiac anomalies and allows growth in preparation for the later stages of the Fontan pathway. The association of HLHS with right congenital diaphragmatic hernia (CDH) is rare. We report performing a successful hybrid stage I palliation on a neonate with HLHS and severe right CDH.

Hypoplastic left heart syndrome: from comfort care to long-term survival

The management of hypoplastic left heart syndrome (HLHS) has changed substantially over the past four decades. In the 1970s, children with HLHS could only be provided with supportive care. As a result, most of these unfortunate children died within the neonatal period. The advent of the Norwood procedure in the early 1980s has changed the prognosis for these children, and the majority now undergoing a series of three surgical stages that can support survival beyond the neonatal period and into early adulthood. This review will focus on the Norwood procedure and the other important innovations of the last half century that have improved our outlook toward children born with HLHS.

Resource and cost considerations in treating hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) was a uniformly fatal diagnosis before 1983, when surgical treatment was first undertaken with the Norwood I operation as the first of 3-staged operations. Since then, operative survival rate of stage I has risen from 53% to over 90% in the current era, not only thanks to technical advances in surgery but also through prenatal diagnosis and imaging, enhanced cardiopulmonary bypass technology, better perioperative intensive care, and closer interstage monitoring. The improvements in patient outcomes achieved through rigorous multidisciplinary teamwork have come at a tremendous cost in manpower and resources, making HLHS still a challenge to all congenital heart programs, established or emerging. We review the various surgical steps to treat HLHS and their current expected outcomes, and put into perspective cost considerations compared to other more “simple” congenital heart defects.

Understanding the Hybrid Stage I Approach for Hypoplastic Left Heart Syndrome

Hybrid stage I palliation combines cardiothoracic surgery and interventional transcatheter procedures for treatment of hypoplastic left heart syndrome. The approach is an alternative to the Norwood procedure, the traditional first stage of surgical palliation. Hybrid stage I palliation involves placing bilateral branch pulmonary artery bands and a patent ductus arteriosus stent through a median sternotomy, performed without cardiopulmonary bypass. The purpose of the bands is to control blood flow to the lungs and protect the pulmonary bed while the stent sustains systemic cardiac output. A balloon atrial septostomy is performed to create an atrial septal defect for unobstructed blood flow from the left atrium to the right atrium. The second stage of palliative surgery is the comprehensive stage II, which incorporates removal of the stent and pulmonary artery bands, atrial septectomy, anastomosis of the diminutive ascending aorta to the main pulmonary artery, aortic arch augmentation, and bidirectional cavopulmonary anastomosis. The traditional Fontan procedure completes the series of palliation.

Hypoplastic left heart syndrome: current perspectives

Since the first successful intervention for hypoplastic left heart syndrome (HLHS) was undertaken by Norwood in 1983, there have been many advancements in the pre-, intra-, and postoperative care of these children for a diagnosis that just 25 years ago was almost certainly a fatal one. This paper aims to describe the most recent trends and perspectives on the treatment of HLHS. In particular, we will discuss the five current options for HLHS, including Norwood stage I as the beginning to 3-stage palliation, transplant, true hybrid, hybrid-bridge-to-Norwood, and compassionate care.

Impact of Norwood versus hybrid palliation on cardiac size and function in hypoplastic left heart syndrome

OBJECTIVE

The hybrid approach for hypoplastic left heart syndrome (HLHS) could theoretically result in better preservation of right ventricular (RV) function then the Norwood procedure. The aim of this study was to compare echocardiographic indices of RV size and function in patients after Norwood and hybrid throughout all stages of palliation.

METHODS

76 HLHS patients (42 Norwood, 34 hybrid) were retrospectively studied. Echocardiography was obtained before stage I, before and after stage II, and before and after Fontan. Median follow-up was 4.9 years (range 1.1-8.5).

RESULTS

Baseline characteristics before stage I were similar. Hybrid patients demonstrated a significant decrease in RV fractional area change (FAC) between baseline and pre-stage II (36±9% vs 27±6%; p<0.01); Norwood patients remained stable (32±10% vs 32±7%; p=0.21). At pre-stage II, moderate/severe tricuspid valve (TV) regurgitation was found in nine Norwood (33%) and four hybrid (18%) patients (p=0.19). After stage II, the difference in FAC became insignificant (29±7% vs 25±8%, p=0.08) and moderate/severe TV regurgitation (TR) was found in 13 Norwood (48%) and four hybrid patients (19%) (p=0.18). At pre-Fontan, RV FAC was similar after Norwood and hybrid (34±5% vs 33±6%, p=0.69), which remained unchanged after Fontan. After Fontan, one Norwood and one hybrid patient had moderate TR. RV and TV size were similar for both groups at each time point.

CONCLUSIONS

Patients after Norwood and hybrid procedures had equivalent indices of RV size, and systolic and diastolic function throughout all stages of palliation. Small differences in individual RV and TV indices are likely to be explained by differences in physiology or surgical timing rather than by intrinsic differences in myocardial and valve function.

Achieving Benchmark Results for Neonatal Palliation of Hypoplastic Left Heart Syndrome and Related Anomalies in an Emerging Program

BACKGROUND

Results of surgical management of hypoplastic left heart syndrome (HLHS) and related anomalies are often compared to published benchmark data which reflect the use of a variety of surgical and hybrid protocols. We report encouraging results achieved in an emerging program, despite a learning curve at all care levels. Rather than relying on a single preferred protocol, surgical management was based on matching surgical strategy to individual patient factors.

METHODS

From 2010 to 2014, a total of 47 consecutive patients with HLHS or related anomalies with ductal-dependent systemic circulation underwent initial surgical palliation, including 30 Norwood stage I, 8 hybrid stage I, and 9 salvage-to-Norwood procedures. True hybrid procedures entailed bilateral pulmonary artery banding and ductal stenting. In the salvage-to-Norwood strategy, ductal stenting was withheld in favor of continued prostaglandin infusion in anticipation of a deferred Norwood procedure. Cardiac comorbidities (obstructed pulmonary venous return, poor ventricular function, and atrioventricular valve regurgitation) and noncardiac comorbidities influenced the choice of treatment strategies and were analyzed as potential risk factors for extracorporeal membrane oxygenation (ECMO) support or in-hospital mortality.

RESULTS

Overall hospital survival was 81% (Norwood 83.3%, hybrid 88%, "salvage" 67%; P = .4942). Extracorporeal membrane oxygenation support was used for eight (17%) patients with two survivors. For cases with obstructed pulmonary venous return (n = 10, 21%), management choices favored a hybrid or salvage strategy (P = .0026). Aortic atresia (n = 22, 47%) was treated by a Norwood or salvage-to-Norwood. No cardiac, noncardiac, or genetic comorbidities were identified as independent risk factors for ECMO or discharge mortality in a multivariable analysis.

CONCLUSIONS

Our emerging program achieved outcomes that compare favorably to published benchmark data with respect to hospital survival. These results reflect rigorous interdisciplinary teamwork and a flexible approach to surgical palliation based on matching surgical strategy to patient factors. With major associated cardiac/noncardiac comorbidity and antegrade coronary flow, a true hybrid with ductal stenting was our preferred strategy. For high-risk situations such as aortic atresia with obstructed pulmonary venous return, the salvage hybrid-bridge-to-Norwood strategy may help achieve survival albeit with increased resource utilization.

Ductal stenting using side-branch cell dilation for aortic coarctation in high-risk patients with hypoplastic left heart syndrome

For high-risk neonates with hypoplastic left heart syndrome (HLHS) undergoing Norwood operation, the strategy of bilateral pulmonary artery banding and ductal stenting is risky in case of coarctation of the aorta (CoA), often resulting in death. Therefore, we devised a new method of ductal stenting with side-branch cell dilation, which could overcome the constriction of the ductal arch with CoA in two HLHS patients. This is the first report that presents this method and the results. © 2015 Wiley Periodicals, Inc.

Benefits of Balloon-Dilatable Bilateral Pulmonary Artery Banding in Patients With Hypoplastic Left Heart Syndrome and Other Complex Cardiac Anomalies

OBJECTIVES

The purpose of this study was to evaluate the potential of balloon-dilatable bilateral pulmonary artery banding (b-PAB) and its impact on the configuration of the pulmonary artery (PA).

BACKGROUND

We have previously used balloon-dilatable b-PAB as first-stage palliation for patients with hypoplastic left heart syndrome (HLHS) and other complex cardiac anomalies.

METHODS

Two pliable tapes were placed around each branch of the PA and tightened with 7-0 polypropylene sutures in a manner that allowed for the subsequent adjustment of PA diameters. We retrospectively examined the adjustability of PA diameters by balloon dilation and the need for surgical PA angioplasty at later stages.

RESULTS

From January 2010 to October 2013, we performed b-PAB in 8 patients, including 3 borderline cases between biventricular repair (BVR) and univentricular repair (UVR). The b-PAB procedures were performed at a median age of 6.5 days (range, 2-10 days). Balloon dilations were performed in 10 lesions in 4 patients. All of the procedures were performed safely. Two patients reached definite BVR. The remaining 6 patients underwent open palliative procedures with univentricular physiologies that resulted in 2 deaths unrelated to the initial b-PAB. In all but 1 of the patients, the PA configuration was properly maintained and did not require surgical pulmonary angioplasty.

CONCLUSIONS

Balloon-dilatable b-PAB can be performed safely and prevents PA distortion at later stages. This technique should be considered for patients with complex cardiac anomalies if uncertainty exists regarding the optimal surgical strategy (BVR or UVR) in early infancy.

Predictors of Prolonged Hospital Length of Stay Following Stage II Palliation of Hypoplastic Left Heart Syndrome (and Variants): Analysis of the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) Database

The objective of this study is to identify predictors of prolonged hospital length of stay (LOS) for single ventricle patients following stage 2 palliation (S2P), excluding patients who underwent a hybrid procedure. We explore the impact of demographic features, stage 1 palliation (S1P), interstage I (IS1) management, S2P, and post-surgical care on hospital LOS following S2P. We conducted a retrospective analysis of the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) database. The NPC-QIC database is an established registry of patients with hypoplastic left heart syndrome (HLHS) and its variants. It contains detailed information regarding the demographic features, S1P, IS1, S2P, and interstage 2 (IS2) management of children with HLHS and related single ventricle cardiac malformations. Between 2008 and 2012, there were 477 participants with recorded LOS data in the NPC-QIC registry. Excluding the 29 patients who underwent hybrid procedure, there were 448 participants who underwent a Norwood (or Norwood-variant procedure) as S1P. In order to be included in the NPC-QIC database, participants were discharged to home following S1P and prior to S2P. We found that postoperative LOS among the 448 S2P procedure recipients is most strongly influenced by the need for reoperation following S2P, the need for an additional cardiac catheterization procedure following S2P, the use of non-oral methods of nutrition (e.g., nasogastric tube, total parental nutrition, gastrostomy tube), and the development of postoperative complications. Factors such as age at the time of S2P, the presence of a major non-cardiac anomaly, site participant volume, IS1 course, the type and number of vasoactive agents used following S2P, and the need for more than 1 intensive care unit (ICU) hospitalization (following discharge to the ward but prior to discharge to home) were significant predictors by univariate analysis but not by multivariate analysis. We excluded participants undergoing the hybrid procedure as S1P from this analysis given that the S2P following the initial hybrid is typically a more complicated procedure. Hospital LOS following S2P among children undergoing the Norwood or Norwood-variant procedure as S1P is most strongly influenced by events following S2P and not demographic or S1P factors. Factors most predictive of prolonged LOS include the need for reoperation, the need for an additional cardiac catheterization procedure following S2P, the need for non-oral methods of nutrition, and the development of postoperative complications.

Hybrid interventional procedures in congenital heart disease

The evolution of congenital cardiac surgery has seen significant innovative advances in collaborative efforts between congenital cardiac surgeons and interventionalists to provide the least invasive intervention with the greatest hemodynamic benefit for patients with congenital heart disease. This review looks at how this collaborative approach has evolved and is being applied to treat a number of congenital conditions across the age ranges.

The hybrid approach for palliation of hypoplastic left heart syndrome: Intermediate results of a single-center experience

INTRODUCTION

Hypoplastic left heart syndrome (HLHS) is a major cause of cardiac death during the first week of life. The hybrid approach is a reliable, reproducible treatment option for patients with HLHS. Herein we report our results using this approach, focusing on its efficacy, safety and late outcome.

METHODS

We reviewed prospectively collected data on patients treated for HLHS using a hybrid approach between July 2007 and September 2014.

RESULTS

Nine patients had a stage 1 hybrid procedure, with seven undergoing a comprehensive stage 2 procedure. One patient completed the Fontan procedure. Five patients underwent balloon atrial septostomy after the hybrid procedure; in three patients, a stent was placed across the atrial septum. There were three deaths: two early after the hybrid procedure and one early after stage two palliation. Overall survival was 66%.

CONCLUSIONS

In our single-center series, the hybrid approach for HLHS yields intermediate results comparable to those of the Norwood strategy. The existence of dedicated teams for the diagnosis and management of these patients, preferably in high-volume centers, is of major importance in this condition.

Early results of neurodevelopment following hybrid stage I for hypoplastic left heart syndrome

Motor skills and neurodevelopment in infants with hypoplastic left heart syndrome (HLHS) who have undergone Hybrid Stage I palliation is unknown. The purpose of this study is to assess early neurodevelopment in infants with HLHS after Hybrid Stage I palliation. Developmental assessment was performed in HLHS infants who underwent Hybrid Stage I palliation at 2 and 4 months of age using the Test of Infant Motor Performance, and at 6 months of age, prior to undergoing the second staged surgery, using the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-III). Results were compared to healthy control subjects and norm-referenced data. The HLHS group scored between -1 and -2 standard deviations (SD) below the mean at 2 months of age (p = 0.002), and within -1 SD of the mean, at 4 months of age (p = 0.0019), on the TIMP. Compared to the control group, composite motor skills were significantly lower at 6 months of age on the Bayley-III in the HLHS group (p = 0.0489), however, not significant for cognitive (p = 0.29) or language (p = 0.68). Percentile rank motor scores were 17 ± 20 % in the HLHS group compared to 85 ± 12 % for the healthy age-matched control group. Infants with HLHS who undergo Hybrid Stage I palliation score lower on standardized motor skill tests compared to healthy age-matched controls and the norm-referenced population. This suggests that infants with HLHS have poorer motor skill performance than typically developing infants at 6 months of age.