Transplantation-free survival and interventions at 3 years in the single ventricle reconstruction trial

Improved National Outcomes Achieved in a Cardiac Learning Health Collaborative Based on Early Performance Level

OBJECTIVE

Within the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC), a learning health network developed to improve outcomes for patients with hypoplastic left heart syndrome and variants, we assessed which centers contributed to reductions in mortality and growth failure.

STUDY DESIGN

Centers within the NPC-QIC were divided into tertiles based on early performance for mortality and separately for growth failure. These groups were evaluated for improvement from the early to late time period and compared with the other groups in the late time period.

RESULTS

Mortality was 3.8% for the high-performing, 7.6% for the medium-performing, and 14.4% for the low-performing groups in the early time period. Only the low-performing group had a significant change (P < .001) from the early to late period. In the late period, there was no difference in mortality between the high- (5.7%), medium- (7%), and low- (4.6%) performing centers (P = .5). Growth failure occurred in 13.9% for the high-performing, 21.9% for the medium-performing, and 32.8% for the low-performing groups in the early time period. Only the low-performing group had a significant change (P < .001) over time. In the late period, there was no significant difference in growth failure between the high- (19.8%), medium- (21.5%), and low- (13.5%) performing groups (P = .054).

CONCLUSIONS

Improvements in the NPC-QIC mortality and growth measures are primarily driven by improvement in those performing the worst in these areas initially without compromising the success of high-performing centers. Focus for improvement may vary by center based on performance.

Fetal Aortic Valvuloplasty for Evolving Hypoplastic Left Heart Syndrome: A Decision Analysis

BACKGROUND

Fetal aortic valvuloplasty (FAV) may prevent progression of midgestation aortic stenosis to hypoplastic left heart syndrome. However, FAV has well-established risks, and its survival benefit remains unknown. Our primary aim was to determine whether FAV for midgestation aortic stenosis increases survival from fetal diagnosis to age 6 years.

METHODS AND RESULTS

We performed a retrospective analysis of 143 fetuses who underwent FAV from 2000 to 2017 and a secondary analysis of the Pediatric Heart Network Single Ventricle Reconstruction trial. Using these results, we developed a decision model to estimate probability of transplant-free survival from fetal diagnosis to age 6 years and postnatal restricted mean transplant-free survival time. FAV was technically successful in 84% of 143 fetuses with fetal demise in 8%. Biventricular circulation was achieved in 50% of 111 live-born infants with successful FAV but in only 16% of the 19 patients with unsuccessful FAV. The model projected overlapping probabilities of transplant-free survival to age 6 years at 75% (95% CI, 67%-82%) with FAV versus 72% (95% CI, 61%-82%) with expectant fetal management, resulting in a restricted mean transplant-free survival time benefit of 1.2 months. When limiting analyses to the improved FAV experience since 2009 to reflect current practice, (probability of technical success [94%], fetal demise [4%], and biventricular circulation [66%]), the model projected that FAV increased the probability of survival to age 6 years to 82% (95% CI, 73%-89%). Expectant management is favored if risk of fetal demise exceeded 12% or probability of biventricular circulation fell below 26%, but FAV remained favored over plausible recent range of technical success.

CONCLUSIONS

Our model suggests that FAV provides a modest, medium-term survival benefit over expectant fetal management. Appropriate patient selection and low risk of fetal demise with FAV are critical factors for obtaining a survival benefit.

Hypoplastic left heart syndrome: current modalities of treatment and outcomes

Hypoplastic left heart syndrome is a constellation of malformations which result from the severe underdevelopment of any left-sided cardiac structures. Once considered to be universally fatal, the prognosis for this condition has tremendously improved over the past four decades since the work of William Norwood in the early 1980s. Today, a staged surgical approach is applied for palliating this distinctive cohort of patients, in which they undergo three operative procedures in the first 10 years of their life. Advancements in medical technologies, surgical techniques, and our growing experience in the management of HLHS have made survival into adulthood a possibility. Through this review, we present the different phases of the staged approach with primary focus on stage 1-its modifications, current technique, alternatives, and latest outcomes.

Impact of Initial Shunt Type on Echocardiographic Indices in Children After Single Right Ventricle Palliations

Background Heart size and function in children with single right ventricle (RV) anomalies may be influenced by shunt type at the Norwood procedure. We sought to identify shunt-related differences during early childhood after staged surgical palliations using echocardiography. Methods We compared echocardiographic indices of RV, neoaortic, and tricuspid valve size and function at 14 months, pre-Fontan, and 6 years in 241 subjects randomized to a Norwood procedure using either the modified Blalock-Taussig shunt or RV-to-pulmonary-artery shunt. Results At 6 years, the shunt groups did not differ significantly in any measure except for increased indexed neoaortic area in the modified Blalock-Taussig shunt. RV ejection fraction improved between pre-Fontan and 6 years in the RV-to-pulmonary artery shunt group but was stable in the modified Blalock-Taussig shunt group. For the entire cohort, RV diastolic and systolic size and functional indices were improved at 6 years compared with earlier measurements, and indexed tricuspid and neoaortic annular area decreased from 14 months to 6 years. The prevalence of ≥moderate tricuspid and neoaortic regurgitation was uncommon and did not vary by group or time period. Diminished RV ejection fraction at the 14-month study was predictive of late death/transplant; the hazard of late death/transplant when RV ejection fraction was <40% was tripled (hazard ratio, 3.18; 95% CI, 1.41-7.17). Conclusions By 6 years after staged palliation, shunt type has not impacted RV size and function, and RV and valvar size and function show beneficial remodeling. Poor RV systolic function at 14 months predicts worse late survival independent of the initial shunt type. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00115934.

[Current surgical options and outcomes for newborns with hypoplastic left heart syndrome]

Since the first successful palliation was performed by Norwood et al. in 1983, there have been substantial changes in diagnosis, management, and outcomes of hypoplastic left heart syndrome, Survival for stage 1 palliation has increased to 90% in many centres, with patients potentially surviving into adulthood. However, the associated morbidity and mortality remain substantial. Although the principles of staged surgical palliation of hypoplastic left heart syndrome are well established, there is significant variability in surgical procedure and management between centres, and several controversial aspects remain unresolved. In this review, we summarize the current surgical and management options for newborns with hypoplastic left heart syndrome and their outcomes.

Neonatal Palliative Care for Complicated Cardiac Anomalies: A 10-Year Experience of an Interdisciplinary Program at a Large Tertiary Cardiac Center

OBJECTIVES

To report the outcomes of a Neonatal Palliative Care (NPC) Program at a large tertiary cardiac center caring for a subset of fetuses and neonates with life-limiting cardiac diagnoses or cardiac diagnoses with medical comorbidities leading to adverse prognoses.

STUDY DESIGN

The Neonatal Comfort Care Program at New York-Presbyterian Morgan Stanley Children's Hospital/Columbia University Medical Center is an interdisciplinary team that offers the option of NPC to neonates prenatally diagnosed with life-limiting conditions, including single ventricle (SV) congenital heart disease (CHD) or less severe forms of CHD complicated by multiorgan dysfunction or genetic syndromes.

RESULTS

From 2008 to 2017, the Neonatal Comfort Care Program cared for 75 fetuses or neonates including 29 with isolated SV CHD, 36 with CHD and multiorgan dysfunction and/or severe genetic abnormalities, and 10 neonates with a prenatal diagnosis of isolated CHD and postnatal diagnoses of severe conditions who were initially in intensive care before transitioning to NPC because of a poor prognosis.

CONCLUSIONS

At New York-Presbyterian Morgan Stanley Children's Hospital/Columbia University Medical Center, a large tertiary cardiac center, 13.5% of parents of fetuses or neonates with isolated SV CHD opted for NPC. Twenty-six of 29 newborns with SV CHD treated with NPC died. Of the remaining, 2 neonates with mixing lesions are alive at 3 and 5 years of age, and 1 neonate was initially treated with NPC and then pursued surgical palliation. These results suggest that NPC is a reasonable choice for neonates with SV CHD.

Selective Use of Inpatient Interstage Management After Norwood Procedure

BACKGROUND

We report our intermediate-term results after Norwood procedure, including use of an interstage inpatient management strategy for high-risk patients, and seek to create a predictive model for probability of discharge.

METHODS

A single-site retrospective review was conducted for all patients undergoing Norwood procedure from 2006 to 2016 (N = 177). We compared those discharged home with those who either remained hospitalized until Glenn procedure or died before Norwood procedure discharge. Multivariable logistic regression was used to develop a predictive model for discharge.

RESULTS

During the study period, 120 (68%) patients were discharged home, 45 (25%) remained hospitalized, and 12 (7%) died before Glenn procedure (median age: 71 days). Interstage survival for those discharged after Norwood procedure was 100%. Longitudinal survival for the cohort was 86%, 81%, and 77% at 1, 5, and 10 years, resepectively. Ten-year survival was significantly greater for the discharged group compared with the interstage inpatients (86% vs 56%, P < .001). A reduced predictive model of discharge included lower gestational age (odds ratio [OR]: 0.95), lower median income for ZIP code (OR: 0.4), lower birth-weight-for-age z-score (OR: 0.56), longer cardiopulmonary bypass time (OR: 0.45), and Blalock-Taussig shunt (OR: 0.32).

CONCLUSIONS

Survival up to 10 years after Norwood procedure is good using a strategy of inpatient care for a subset of high-risk patients to mitigate home interstage mortality. A probabilistic model used after Norwood procedure was able to predict interstage discharge with good accuracy, but will require external validation to ensure generalizability. Further work is also needed to determine optimal palliative pathways for the high-risk patients because of the notable attrition beyond successful bidirectional Glenn procedure.

Experience of a single institution with femoral vein homograft as right ventricle to pulmonary artery conduit in stage 1 Norwood operation

OBJECTIVE

Femoral vein homograft can be used be used as valved right ventricle to pulmonary artery conduit in the Norwood operation. We describe the results of this approach, including pulmonary artery growth and ventricular function.

METHODS

A retrospective chart review of 24 consecutive neonates with hypoplastic left heart syndrome or complex single ventricle undergoing this approach between June 2012 and December 2017 was performed. Conduit valve competency and ventricular function were estimated using transthoracic echocardiogram, and pulmonary artery growth was measured using Nakata's index. Changes in ventricular function pre-Glenn and at latest follow-up were assessed by ordinal logistic regression with a general linear model to account for the correlation within the same patient over time.

RESULTS

Median age at surgery was 4 days, and mean weight was 3 kg. There was no interstage mortality. A total of 21 patients have undergone Glenn operation, and 9 patients have completed the Fontan operation. None of the conduits developed thrombosis. Sixty-three percent of conduits remained competent in the first month, and 33% remained competent after 3 months of operation. Catheter interventions on conduits were necessary in 14 patients. Median Nakata index at pre-Glenn catheterization was 228 mm²/m² (interquartile range, 107-341 mm²/m²). Right ventricular function was preserved in 83% of patients at a median follow-up of 34 (interquartile range, 10-46) months.

CONCLUSIONS

Femoral vein homograft as a right ventricle to pulmonary artery conduit in the Norwood operation is safe and associated with good pulmonary artery growth and preserved ventricular function as assessed by subjective echocardiography. Catheter intervention of the conduit may be necessary.

Hypoplastic left heart syndrome [HLHS]: treatment options in present era

Hypoplastic left heart syndrome (HLHS) is the most severe form of congenital heart defect (CHD). The first successful intervention for it was undertaken by Norwood in 1983. Since then, there have been much development in the pre, intra, and postoperative treatment option in staged palliative surgical procedures. Early diagnostic management, prenatal interventions, innovative diagnostic methods, constantly modified surgical techniques, and hybridization contribute to a significant progress in treatment options. This will allow for defining an optimal strategy of improving survival and quality of life in HLHS patients. The development of intervention cardiology makes possible the stepwise treatment of the defect with one operation only. The first and third stage may be done by hybrid or interventional methods, then only the second stage of treatment needs to be done surgically. The world experience and all the available literature says that the 1st-stage procedure could be done now safely either directly or with a bridge to Norwood followed by the stage 2 with a Glen or Hemi-Fontan and followed by a Fontan down the lane surgically.

The Case for Cardiac Xenotransplantation in Neonates: Is Now the Time to Reconsider Xenotransplantation for Hypoplastic Left Heart Syndrome?

Neonatal cardiac transplantation for hypoplastic left heart syndrome (HLHS) is associated with excellent long-term survival compared to older recipients. However, heart transplantation for neonates is greatly limited by the critical shortage of donor hearts, and by the associated mortality of the long pre-transplant waiting period. This led to the development of staged surgical palliation as the first-line surgical therapy for HLHS. Recent advances in genetic engineering and xenotransplantation have provided the potential to replicate the excellent results of neonatal cardiac allotransplantation while eliminating wait-list-associated mortality through genetically modified pig-to-human neonatal cardiac xenotransplantation. The elimination of the major pig antigens in addition to the immature B-cell response in neonates allows for the potential to induce B-cell tolerance. Additionally, the relatively mature neonatal T-cell response could be reduced by thymectomy at the time of operation combined with donor-specific pig thymus transplantation to "reprogram" the host's T-cells to recognize the xenograft as host tissue. In light of the recent significantly increased graft survival of genetically-engineered pig-to-baboon cardiac xenotransplantation, we propose that now is the time to consider devoting research to advance the potential clinical application of cardiac xenotransplantation as a treatment option for patients with HLHS. Employing cardiac xenotransplantation could revolutionize therapy for complex congenital heart defects and open a new chapter in the field of pediatric cardiac transplantation.

Pathophysiology, adaptation, and imaging of the right ventricle in Fontan circulation

The Fontan procedure, which creates a total cavopulmonary anastomosis and represents the final stage of palliation for hypoplastic left heart syndrome, generates a unique circulation relying on a functionally single right ventricle (RV). The RV pumps blood in series around the systemic and pulmonary circulation, which requires adaptations to the abnormal volume and pressure loads. Here, we provide a complete review of RV adaptations as the RV assumes the role of the systemic ventricle, the progression of RV dysfunction to a distinct pattern of heart failure unique to this disease process, and the assessment and management strategies used to protect and rehabilitate the failing RV of Fontan circulation.

Hypoplastic left heart syndrome: from fetus to fontan

The care of children with hypoplastic left heart syndrome is constantly evolving. Prenatal diagnosis of hypoplastic left heart syndrome will aid in counselling of parents, and selected fetuses may be candidates for in utero intervention. Following birth, palliation can be undertaken through staged operations: Norwood (or hybrid) in the 1st week of life, superior cavopulmonary connection at 4-6 months of life, and finally total cavopulmonary connection (Fontan) at 2-4 years of age. Children with hypoplastic left heart syndrome are at risk of circulatory failure their entire life, and selected patients may undergo heart transplantation. In this review article, we summarise recent advances in the critical care management of patients with hypoplastic left heart syndrome as were discussed in a focused session at the 12th International Conference of the Paediatric Cardiac Intensive Care Society held on 9 December, 2016, in Miami Beach, Florida.

Fetal interventions for structural heart disease

Fetal cardiac intervention (FCI) offers the potential to alter in utero anatomy and physiology. For aortic stenosis with evolving hypoplastic left heart syndrome and pulmonary atresia with intact ventricular septum with evolving hypoplastic right heart syndrome, FCI may result in maintenance of a biventricular circulation, thus avoiding single-ventricle palliation and its attendant complications. In the case of hypoplastic left heart syndrome with intact atrial septum, FCI may ameliorate in utero pathophysiology and portend a more favorable postnatal prognosis. In all cases, a detailed fetal echocardiographic assessment to identify the appropriate FCI candidate is essential. This article reviews the three aforementioned lesions for which FCI can be considered. The pathophysiology and rationale for intervention, echocardiographic assessment, patient selection criteria, and outcomes for each lesion will be reviewed. A primary focus will be the echocardiographic evaluation of each lesion.

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.

Survival to Stage II with Ventricular Dysfunction: Secondary Analysis of the Single Ventricle Reconstruction Trial

Ventricular dysfunction affects survival in patients with single right ventricle (RV), and remains one of the primary indications for heart transplantation. Since it is challenging to predict the capacity of patients with ventricular dysfunction to proceed to the stage II procedure, we sought to identify factors that would be associated with death or heart transplantation without achieving stage II for single RV patients with ventricular dysfunction after Norwood procedure. The Single Ventricle Reconstruction (SVR) trial public-use database was used. Patients with a RV ejection fraction less than 44% or a RV fractional area of change less than 35% on the post-Norwood echocardiogram were included. Parametric risk hazard analysis was used to identify risk factors for death or transplantation without achieving stage II. Of 365 patients with ventricular function measurements on the post-Norwood echocardiogram, 123 (34%) patients had RV dysfunction. The transplantation-free survival was significantly lower for those with ventricular dysfunction compared to those with normal function (log rank Chi-square = 4.23, p = 0.04). Furthermore, having a Blalock-Taussig (BT) shunt, a large RV, a post-Norwood infectious complication, and a surgeon who performs five or less Norwood per year were independent risk factors for death or transplantation without achieving stage II. The predicted 6-month transplantation-free survival for patients with all four identified risk factors was 1% (70% CI 0-13%). Early heart transplantation referral might be considered for post-Norwood patients with BT shunt and RV dysfunction, especially if other high-risk features are present.

Reduced Right Ventricular Fractional Area Change, Strain, and Strain Rate before Bidirectional Cavopulmonary Anastomosis is Associated with Medium-Term Mortality for Children with Hypoplastic Left Heart Syndrome

BACKGROUND

Ventricular dysfunction is associated with increased morbidity and mortality in children with hypoplastic left heart syndrome. The aim of this study was to assess the diagnostic performance of conventional and speckle-tracking echocardiographic measures of right ventricular (RV) function before bidirectional cavopulmonary anastomosis palliation in predicting death or need for heart transplantation (HTx).

METHODS

RV fractional area change (RVFAC) and longitudinal and circumferential strain and strain rate (SR) were measured in 64 prospectively recruited patients with hypoplastic left heart syndrome from echocardiograms obtained before bidirectional cavopulmonary anastomosis surgery. The composite end point of death or HTx was examined. Receiver operating characteristic analysis was performed, and cutoff values optimizing sensitivity and specificity were derived.

RESULTS

At a median follow-up of 5.0 years (interquartile range, 2.8-6.4 years), 13 patients meeting the composite end point had lower longitudinal strain and SR, circumferential SR, and RVFAC compared with survivors (n = 51). The conventional cutoff of RVFAC < 35% was specific for death or HTx (86%) but had poor sensitivity (46%), with an area under the curve of 0.73. Speckle-tracking echocardiographic variables showed similar areas under the curve (range, 0.69-0.79), with negative predictive values >90%. Addition of speckle-tracking echocardiographic variables to RVFAC < 35% showed no added benefit. However, in a subpopulation of patients with RVFAC ≥ 35% (n = 44), those meeting the composite end point (n = 7) had lower longitudinal SR (median, -1.0 1/sec [interquartile range, -0.8 to -1.1 1/sec] vs -1.21/sec [interquartile range, -1.0 to -1.3 1/sec], P = .03). Interobserver reproducibility was superior for longitudinal strain and SR (intraclass correlation coefficient > 0.92) compared with RVFAC (intraclass correlation coefficient = 0.75).

CONCLUSIONS

Children with hypoplastic left heart syndrome with normal RVFAC and ventricular deformation before bidirectional cavopulmonary anastomosis have a low likelihood of death or HTx in the medium term. In the presence of reduced RVFAC, speckle-tracking echocardiography does not provide additional prognostic value. However, in patients with "normal" RVFAC, it may have a role in improving outcome prediction and warrants further investigation.

Randomized controlled trials in children's heart surgery in the 21st century: a systematic review

OBJECTIVES

Randomized controlled trials are the gold standard for evaluating health care interventions, yet are uncommon in children's heart surgery. We conducted a systematic review of clinical trials in paediatric cardiac surgery to evaluate the scope and quality of the current international literature.

METHODS

We searched MEDLINE, CENTRAL and LILACS, and manually screened retrieved references and systematic reviews to identify all randomized controlled trials reporting the effect of any intervention on the conduct or outcomes of heart surgery in children published in any language since January 2000; secondary publications and those reporting inseparable adult data were excluded. Two reviewers independently screened studies for eligibility and extracted data; the Cochrane Risk of Bias tool was used to assess for potential biases.

RESULTS

We identified 333 trials from 34 countries randomizing 23 902 children. Most were early phase (313, 94.0%), recruiting few patients (median 45, interquartile range 28-82), and only 11 (3.3%) directly evaluated a surgical intervention. One hundred and nine (32.7%) trials calculated a sample size, 52 (15.6%) reported a CONSORT diagram, 51 (15.3%) were publicly registered and 25 (7.5%) had a Data Monitoring Committee. The overall risk of bias was low in 22 (6.6%), high in 69 (20.7%) and unclear in 242 (72.7%).

CONCLUSIONS

The recent literature in children's heart surgery contains few late-phase clinical trials. Most trials did not conform to the accepted standards of reporting, and the overall risk of bias was low in few studies. There is a need for high-quality, multicentre clinical trials to provide a robust evidence base for contemporary paediatric cardiac surgical practice.

Prolonged PR Interval at Birth Predicting the High Occurrence of Fatal Atrioventricular Block in Hypoplastic Left Heart Syndrome

Infants with hypoplastic left heart syndrome (HLHS) are at high mortality especially when they are associated with bradyarrhythmias. However, the risk factor of developing high-grade atrioventricular block (HAVB) is still unclear. Seventy-three patients with HLHS in our institutions from 2002 to 2011 were enrolled. The survival rate was assessed by the anatomical types, treatments, occurrence of HAVB, severe tricuspid regurgitation (TR), and restrictive atrial septal defect (ASD) along with electrocardiogram findings at birth. There were 23 (32%) cardiogenic and 7 (10%) non-cardiogenic deaths. The occurrence rate of HAVB but not severe TR or restrictive ASD was higher in 30 deceased patients than in 43 survived patients [7 (23%) vs. 1 (2.3%), p = 0.0038]. The overall mortality rate was higher in patients with HAVB than in those without it (p = 0.0002). Of 7 deceased patients with HAVB, 6 HAVB occurred within 10 days post-surgery, and 3 HAVB led to the early death. The mortality rate of patients with prolonged PR (≥ 0.15 s) but not wide QRS (> 0.08 s) or prolonged QTc (> 0.43 s) at birth was higher than each without it (p = 0.0106). Multivariate analysis indicated that prolonged PR but no other variables was independently associated with the mortality (hazard ratio: 2.948, p = 0.0104). Prolonged PR at birth in HLHS infants predicts the development of fatal HAVB.

Heart failure after the Norwood procedure: An analysis of the Single Ventricle Reconstruction Trial

BACKGROUND

Heart failure results in significant morbidity and mortality in young children with hypoplastic left heart syndrome (HLHS) after the Norwood procedure.

METHODS

We studied subjects enrolled in the prospective Single Ventricle Reconstruction (SVR) Trial who survived to hospital discharge after a Norwood operation and were followed up to age 6 years. The primary outcome was heart failure, defined as heart transplant listing after Norwood hospitalization, death attributable to heart failure, or symptomatic heart failure (New York Heart Association [NYHA] Class IV). Multivariate modeling was undertaken using Cox regression methodology to determine variables associated with heart failure.

RESULTS

Of the 461 subjects discharged home following a Norwood procedure, 66 (14.3%) met the criteria for heart failure. Among these, 15 died from heart failure, 39 were listed for transplant (22 had a transplant, 12 died after listing, and 5 were alive and not yet transplanted), and 12 had NYHA Class IV heart failure but were never listed. The median age at heart failure identification was 1.28 (interquartile range 0.30 to 4.69) years. Factors associated with early heart failure included post-Norwood lower fractional area change, need for extracorporeal membrane oxygenation, non-Hispanic ethnicity, Norwood perfusion type, and total support time (p < 0.05).

CONCLUSIONS

By 6 years of age, heart failure developed in nearly 15% of children after the Norwood procedure. Although transplant listing was common, many patients died from heart failure before receiving a transplant or without being listed. Shunt type did not impact the risk of developing heart failure.

Norwood Procedure for Palliation of Hypoplastic Left Heart Syndrome: Right Ventricle to Pulmonary Artery Conduit vs Modified Blalock-Taussig Shunt

Patients with hypoplastic left heart syndrome undergo a series of operations to separate the pulmonary and systemic circulations. The first of at least 3 operations occurs in the newborn period, with a stage I palliation. The goal of stage I palliation is to provide pulmonary blood flow and create an unobstructed systemic outflow tract. Advances in surgical techniques and intraoperative and postoperative care have helped decrease morbidity and mortality for patients with hypoplastic left heart syndrome who have the stage I Norwood operation, but the patients continue to be at increased risk for hemodynamic collapse and adverse outcomes. This article discusses risk factors, surgical approach, postoperative nursing and medical management strategies, differences between and outcomes for the Norwood operation with the right ventricle to pulmonary artery conduit and the Norwood operation with a modified Blalock-Taussig shunt.

Transplant-Free Survival and Interventions at 6 Years in the SVR Trial

BACKGROUND

In the SVR trial (Single Ventricle Reconstruction), 1-year transplant-free survival was better for the Norwood procedure with right ventricle-to-pulmonary artery shunt (RVPAS) compared with a modified Blalock-Taussig shunt in patients with hypoplastic left heart and related syndromes. At 6 years, we compared transplant-free survival and other outcomes between the groups.

METHODS

Medical history was collected annually using medical record review, telephone interviews, and the death index. The cohort included 549 patients randomized and treated in the SVR trial.

RESULTS

Transplant-free survival for the RVPAS versus modified Blalock-Taussig shunt groups did not differ at 6 years (64% versus 59%, P=0.25) or with all available follow-up of 7.1±1.6 years (log-rank P=0.13). The RVPAS versus modified Blalock-Taussig shunt treatment effect had nonproportional hazards (P=0.009); the hazard ratio (HR) for death or transplant favored the RVPAS before stage II surgery (HR, 0.66; 95% confidence interval, 0.48-0.92). The effect of shunt type on death or transplant was not statistically significant between stage II to Fontan surgery (HR, 1.36; 95% confidence interval, 0.86-2.17; P=0.17) or after the Fontan procedure (HR, 0.76; 95% confidence interval, 0.33-1.74; P=0.52). By 6 years, patients with RVPAS had a higher incidence of catheter interventions (0.38 versus 0.23/patient-year, P<0.001), primarily because of more interventions between the stage II and Fontan procedures (HR, 1.72; 95% confidence interval, 1.00-3.03). Complications did not differ by shunt type; by 6 years, 1 in 5 patients had had a thrombotic event, and 1 in 6 had had seizures.

CONCLUSIONS

By 6 years, the hazards of death or transplant and catheter interventions were not different between the RVPAS versus modified Blalock-Taussig shunt groups. Children assigned to the RVPAS group had 5% higher transplant-free survival, but the difference did not reach statistical significance, and they required more catheter interventions. Both treatment groups have accrued important complications.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Long term survival of hypoplastic left heart syndrome infants: Meta-analysis comparing outcomes from the modified Blalock-Taussig shunt and the right ventricle to pulmonary artery shunt

BACKGROUND

Stage 1 palliation of hypoplastic left heart syndrome (HLHS) involves the Norwood procedure combined with a modified Blalock-Taussig shunt (mBTS) or right ventricle to pulmonary artery shunt (RVPAS). Short-term survival has been described previously, whereas longer-term outcomes remain a subject of debate. This meta-analysis aimed to describe the short and long-term survival outcomes of these two shunts, and explore factors that might influence survival.

METHODS

Medline, Cochrane Libraries and EMBASE were systematically searched, and 32 studies were included for statistical synthesis, comprising 1348 mBTS and 1258 RVPAS patients.

RESULTS

While early in-hospital survival was superior in the RVPAS group (RR=1.5, p<0.05, 95% CI: 1.21-1.85), this difference was lost from 2years post-stage 1 palliation (RR=0.91, p>0.05, 95% CI: 0.79-1.04), and maintained unchanged up to 6years. This shift in survival was also reflected in inter-stage survival, with superior RVPAS outcomes between stage 1 and 2 (RR=1.62, p<0.05, 95% CI: 1.39-1.88), and equivalent outcomes between stage 2 and 3. Potential contributors to this included a significantly higher rate of pulmonary artery stenosis in the RVPAS group and an increased requirement for shunt re-intervention in this group prior to stage 2.

CONCLUSIONS

Despite early advantages, RVPAS and mBTS for palliation of hypoplastic left heart syndrome produced comparable long-term survival. The RVPAS patients experienced more pulmonary artery stenosis and requirement for shunt re-intervention. The impact of shunt type on quality and survival with a Fontan is yet to be assessed.

Interventional treatments and risk factors in patients born with hypoplastic left heart syndrome in England and Wales from 2000 to 2015

Objective

To describe the long-term outcomes, treatment pathways and risk factors for patients diagnosed with hypoplastic left heart syndrome (HLHS) in England and Wales.

Methods

The UK’s national audit database captures every procedure undertaken for congenital heart disease and updated life status for resident patients in England and Wales. Patients with HLHS born between 2000 and 2015 were identified using codes from the International Paediatric and Congenital Cardiac Code.

Results

There were 976 patients with HLHS. Of these, 9.6% had a prepathway intervention, 89.5% underwent a traditional pathway of staged palliation and 6.4% of infants underwent a hybrid pathway. Patients undergoing prepathway procedures or the hybrid pathway were more complex, exhibiting higher rates of prematurity and acquired comorbidity. Prepathway intervention was associated with the highest in-hospital mortality (34.0%).

44.6% of patients had an off-pathway procedure after their primary procedure, most frequently stenting or dilation of residual or recoarctation and most commonly occurring between stage 1 and stage 2.

The survival rate at 1 year and 5 years was 60.7% (95% CI 57.5 to 63.7) and 56.3% (95% CI 53.0 to 59.5), respectively. Patients with an antenatal diagnosis (multivariable HR (MHR) 1.63 (95% CI 1.12 to 2.38)), low weight (<2.5 kg) (MHR 1.49 (95% CI 1.05 to 2.11)) or the presence of an acquired comorbidity (MHR 2.04 (95% CI 1.30 to 3.19)) were less likely to survive.

Conclusion

Treatment pathways among patients with HLHS are complex and variable. It is essential that the long-term outcomes of conditions like HLHS that require serial interventions are studied to provide a fuller picture and to inform quality assurance and improvement.

Impact of Cardiac Progenitor Cells on Heart Failure and Survival in Single Ventricle Congenital Heart Disease

RATIONALE

Intracoronary administration of cardiosphere-derived cells (CDCs) in patients with single ventricles resulted in a short-term improvement in cardiac function.

OBJECTIVE

To test the hypothesis that CDC infusion is associated with improved cardiac function and reduced mortality in patients with heart failure.

METHODS AND RESULTS

We evaluated the effectiveness of CDCs using an integrated cohort study in 101 patients with single ventricles, including 41 patients who received CDC infusion and 60 controls treated with staged palliation alone. Heart failure with preserved ejection fraction (EF) or reduced EF was stratified by the cardiac function after surgical reconstruction. The main outcome measure was to evaluate the magnitude of improvement in cardiac function and all-cause mortality at 2 years. Animal studies were conducted to clarify the underlying mechanisms of heart failure with preserved EF and heart failure with reduced EF phenotypes. At 2 years, CDC infusion increased ventricular function (stage 2: +8.4±10.0% versus +1.6±6.4%, P=0.03; stage 3: +7.9±7.5% versus -1.1±5.5%, P<0.001) compared with controls. In all available follow-up data, survival did not differ between the 2 groups (log-rank P=0.225), whereas overall patients treated by CDCs had lower incidences of late failure (P=0.022), adverse events (P=0.013), and catheter intervention (P=0.005) compared with controls. CDC infusion was associated with a lower risk of adverse events (hazard ratio, 0.411; 95% CI, 0.179-0.942; P=0.036). Notably, CDC infusion reduced mortality (P=0.038) and late complications (P<0.05) in patients with heart failure with reduced EF but not with heart failure with preserved EF. CDC-treated rats significantly reversed myocardial fibrosis with differential collagen deposition and inflammatory responses between the heart failure phenotypes.

CONCLUSIONS

CDC administration in patients with single ventricles showed favorable effects on ventricular function and was associated with reduced late complications except for all-cause mortality after staged procedures. Patients with heart failure with reduced EF but not heart failure with preserved EF treated by CDCs resulted in significant improvement in clinical outcome.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifiers: NCT01273857 and NCT01829750.

Transplantation in the single ventricle population

The single ventricle patient population comprises the most complex cohort presenting to the cardiac transplant team, in terms of demographics, anatomic substrate, and unique physiology. It is also the most rapidly growing diagnostic group presenting for heart transplantation. In this manuscript, we aim to describe the changing landscape of transplantation in single ventricle conditions through reflection on our own institution's practice and experience, alongside contemporary literature review. Single ventricle patients are heterogeneous in terms of age, anatomic diagnosis and physiology according to surgical stage of repair. Progress in surgical palliative strategies has impacted upon the present composition of the population, with growing numbers of hypoplastic left heart syndrome patients and those with late physiology failure following Fontan completion. Multiple prior surgeries, immunological sensitivity and multi-organ involvement impart high peri-operative risk but can be mitigated in part by careful pre-operative planning by a dedicated multi-disciplinary team addressing issues such as planning of concurrent reconstructive surgery, minimizing the post-operative effect of collaterals, timely harvesting, oversizing of donor organs to minimize graft failure, and strategies to address anticipated post-operative elevation in pulmonary vascular resistance. Determining optimal timing for transplant in these patients remains unclear, but understanding the risk of alternative surgical options can help guide decision making with regards to listing.

Interstage evaluation of homograft-valved right ventricle to pulmonary artery conduits for palliation of hypoplastic left heart syndrome

OBJECTIVE

Palliation of hypoplastic left heart syndrome with a standard nonvalved right ventricle to pulmonary artery conduit results in an inefficient circulation in part due to diastolic regurgitation. A composite right ventricle pulmonary artery conduit with a homograft valve has a hypothetical advantage of reducing regurgitation, but may differ in the propensity for stenosis because of valve remodeling.

METHODS

This retrospective cohort study included 130 patients with hypoplastic left heart syndrome who underwent a modified stage 1 procedure with a right ventricle to pulmonary artery conduit from 2002 to 2015. A composite valved conduit (cryopreserved homograft valve anastomosed to a polytetrafluoroethylene tube) was placed in 100 patients (47 aortic, 32 pulmonary, 13 femoral/saphenous vein, 8 unknown), and a nonvalved conduit was used in 30 patients. Echocardiographic functional parameters were evaluated before and after stage 1 palliation and before the bidirectional Glenn procedure, and interstage interventions were assessed.

RESULTS

On competing risk analysis, survival over time was better in the valved conduit group (P = .040), but this difference was no longer significant after adjustment for surgical era. There was no significant difference between groups in the cumulative incidence of bidirectional Glenn completion (P = .15). Patients with a valved conduit underwent more interventions for conduit obstruction in the interstage period, but this difference did not reach significance (P = .16). There were no differences between groups in echocardiographic parameters of right ventricle function at baseline or pre-Glenn.

CONCLUSIONS

In this cohort of patients with hypoplastic left heart syndrome, inclusion of a valved right ventricle to pulmonary artery conduit was not associated with any difference in survival on adjusted analysis and did not confer an identifiable benefit on right ventricle function.

The boundaries of fetal cardiac intervention: Expand or tighten?

Fetal cardiac intervention (FCI) is a relatively new and continually evolving field, and, for select cardiac defects, offers the potential to alter the progression of the disease and improve outcomes. It is a procedure that requires a collaborative effort between maternal-fetal medicine, interventional cardiology and fetal echo/ultrasound specialists, as well as fetal and maternal anesthesiologists, nursing specialists, and social workers. This article reviews the most recently reported data and advances in FCI. Currently, FCI is most frequently performed in fetuses with severe aortic stenosis (AS) with evolving hypoplastic left heart syndrome (eHLHS), established HLHS with intact or highly restrictive atrial septum (IAS), and pulmonary atresia with intact ventricular septum (PA-IVS) with evolving hypoplastic right heart syndrome (eHRHS). The goal of FCI for eHLHS and eHRHS is to promote a postnatal biventricular circulation with, theoretically, the potential for better long-term outcomes. In HLHS with IAS the aim is to improve survival. Contemporary data for FCI demonstrate limited maternal risks and improving technical success. With experience, FCI in severe AS with eHLHS has shown improved rates of biventricular outcome and early survival. Limited data for PA-IVS show promise for improving postnatal biventricular outcomes; however, for HLHS with IAS, FCI has yet to clearly demonstrate improved survival. FCI has an evolving role in the management of congenital heart defects. Ongoing analysis of disease progression, patient selection and postnatal outcomes, in conjuncture with technologic innovations and a multicenter collaborative approach, is essential as the field expands.

Fibrosis-Related Gene Expression in Single Ventricle Heart Disease

OBJECTIVE

To evaluate fibrosis and fibrosis-related gene expression in the myocardium of pediatric subjects with single ventricle with right ventricular failure.

STUDY DESIGN

Real-time quantitative polymerase chain reaction was performed on explanted right ventricular myocardium of pediatric subjects with single ventricle disease and controls with nonfailing heart disease. Subjects were divided into 3 groups: single ventricle failing (right ventricular failure before or after stage I palliation), single ventricle nonfailing (infants listed for primary transplantation with normal right ventricular function), and stage III (Fontan or right ventricular failure after stage III). To evaluate subjects of similar age and right ventricular volume loading, single ventricle disease with failure was compared with single ventricle without failure and stage III was compared with nonfailing right ventricular disease. Histologic fibrosis was assessed in all hearts. Mann-Whitney tests were performed to identify differences in gene expression.

RESULTS

Collagen (Col1α, Col3) expression is decreased in single ventricle congenital heart disease with failure compared with nonfailing single ventricle congenital heart disease (P = .019 and P = .035, respectively), and is equivalent in stage III compared with nonfailing right ventricular heart disease. Tissue inhibitors of metalloproteinase (TIMP-1, TIMP-3, and TIMP-4) are downregulated in stage III compared with nonfailing right ventricular heart disease (P = .0047, P = .013 and P = .013, respectively). Matrix metalloproteinases (MMP-2, MMP-9) are similar between nonfailing single ventricular heart disease and failing single ventricular heart disease, and between stage III heart disease and nonfailing right ventricular heart disease. There is no difference in the prevalence of right ventricular fibrosis by histology in subjects with single ventricular failure heart disease with right ventricular failure (18%) compared with those with normal right ventricular function (38%).

CONCLUSIONS

Fibrosis is not a primary contributor to right ventricular failure in infants and young children with single ventricular heart disease. Additional studies are required to understand whether antifibrotic therapies are beneficial in this population.

Histone deacetylase adaptation in single ventricle heart disease and a young animal model of right ventricular hypertrophy

BackgroundHistone deacetylase (HDAC) inhibitors are promising therapeutics for various forms of cardiac diseases. The purpose of this study was to assess cardiac HDAC catalytic activity and expression in children with single ventricle (SV) heart disease of right ventricular morphology, as well as in a rodent model of right ventricular hypertrophy (RVH).MethodsHomogenates of right ventricle (RV) explants from non-failing controls and children born with a SV were assayed for HDAC catalytic activity and HDAC isoform expression. Postnatal 1-day-old rat pups were placed in hypoxic conditions, and echocardiographic analysis, gene expression, HDAC catalytic activity, and isoform expression studies of the RV were performed.ResultsClass I, IIa, and IIb HDAC catalytic activity and protein expression were elevated in the hearts of children born with a SV. Hypoxic neonatal rats demonstrated RVH, abnormal gene expression, elevated class I and class IIb HDAC catalytic activity, and protein expression in the RV compared with those in the control.ConclusionsThese data suggest that myocardial HDAC adaptations occur in the SV heart and could represent a novel therapeutic target. Although further characterization of the hypoxic neonatal rat is needed, this animal model may be suitable for preclinical investigations of pediatric RV disease and could serve as a useful model for future mechanistic studies.

Association of Shunt Type With Arrhythmias After Norwood Procedure

BACKGROUND

Transplant-free survival for single right ventricle (RV) lesions remains less than 70% at 3 years. Arrhythmia burden, influence of shunt type at Norwood procedure (RV-to-pulmonary artery shunt [RVPAS] versus Blalock-Taussig shunt [BTS]), and implications for mortality risk are not well defined.

METHODS

The authors performed a single-center retrospective analysis of patients with single RV lesions enrolled in a prospective study of arrhythmias after congenital heart surgery.

RESULTS

Fifty-eight patients received a RVPAS and 62 received a BTS, with a median follow-up of 773 days. Overall arrhythmia incidence was 78%, two-thirds of which prompted intervention. Among all types of arrhythmias, only ventricular arrhythmias (VAs) differed by shunt type, which were more common in patients receiving an RVPAS (29% RVPAS versus 14% BTS; p = 0.049). The majority of VAs were transient (69% less than 1 minute), and typically occurred early post-Norwood procedure (median 12 days). No additional variables were associated with development of VAs. Shunt type did not influence transplant-free survival. Within the entire cohort, there was a trend toward increased mortality with prior history of VA (odds ratio, 2.90; 95% confidence interval, 0.99 to 8.90; p = 0.052). For interstage survivors to Glenn palliation, any VA associated with a 14-fold increased risk of death or transplant (hazard ratio, 14.00; 95% confidence interval, 3.66 to 53.40; p < .001). No other tachyarrhythmia or bradyarrhythmia was associated with mortality.

CONCLUSIONS

In this cohort with single RV lesions and prospective rhythm surveillance, patients receiving an RVPAS at Norwood surgery had an increased incidence of VAs compared with patients with a BTS. VAs correlated with late mortality in patients who survived the interstage period.

Congenital pulmonary lymphangiectasia and early mortality after stage 1 reconstruction procedures

OBJECTIVES

Pulmonary lymphangiectasia associated with hypoplastic left heart syndrome with an intact or restrictive atrial septum may result from increased left atrial pressure, and is associated with worse outcomes following staged reconstruction due to lung dysfunction and significant hypoxaemia. Our objective was to characterise the incidence of pulmonary lymphangiectasia in cases of early mortality following stage 1 reconstructions.

METHODS

An institutional cardiac surgical database was retrospectively searched for patients who died within 30 days following a stage 1 reconstruction between 1 January, 1984 and 31 December, 2013. During that period, 1669 stage 1 procedures were performed. Autopsy lung specimens were reviewed by a paediatric pathologist. Patients who died of suspected technical issues were excluded.

RESULTS

A total of 54 patients were included, and of these seven cases (8.5%) of pulmonary lymphangiectasia were identified. The mean estimated gestational age was 38.2±2.4 weeks, and the mean birth weight was 3.0±0.6 kg. The median interval between surgery and death was 1 day (with a range from 0 to 18 days). The atrial septum was intact in one patient (14.3%), restrictive in three patients (42.9%), and unrestrictive in three patients (42.9%).

CONCLUSIONS

Pulmonary lymphangiectasia may develop in hypoplastic left heart syndrome with or without a restrictive atrial septum. As standard prenatal diagnostic evaluations and treatment methods for pulmonary lymphangiectasia are limited, this may be an important contributor to early and late mortality following stage 1 reconstruction for hypoplastic left heart syndrome.

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.

Reduced cortical volume and thickness and their relationship to medical and operative features in post-Fontan children and adolescents

BACKGROUND

We compared brain cortical and subcortical gray matter volumes and cortical thickness between post-Fontan patients and healthy controls, and examined brain anatomical associations with operative and medical history characteristics.

METHODS

Post-Fontan (n = 128 volumes; n = 115 thickness) and control subjects (n = 48 volumes; n = 45 thickness) underwent brain MRI at ages 10-19 y. Subcortical and cortical volumes and cortical thicknesses were measured for intergroup comparison. Associations between brain measures and clinical measures were assessed in the Fontan group.

RESULTS

Widespread, significant reduction in brain volumes and thicknesses existed in the Fontan group compared to controls, spanning all brain lobes and subcortical gray matter. Fontan subjects treated with vs. without the Norwood procedure had smaller volumes in several terminal clusters, but did not differ in cortical thickness. Older age at first operation and increasing numbers of cardiac catheterizations, operative complications, and catheterization complications were associated with lower regional volumes and thicknesses. Increasing numbers of operative complications and cardiac catheterizations were associated with smaller regional volumes in the Norwood group.

CONCLUSION

The post-Fontan adolescent brain differs from the normal control brain. Some of these differences are associated with potentially modifiable clinical variables, suggesting that interventions might improve long-term neurocognitive outcome.

Myocardial Architecture, Mechanics, and Fibrosis in Congenital Heart Disease

Congenital heart disease (CHD) is the most common category of birth defect, affecting 1% of the population and requiring cardiovascular surgery in the first months of life in many patients. Due to advances in congenital cardiovascular surgery and patient management, most children with CHD now survive into adulthood. However, residual and postoperative defects are common resulting in abnormal hemodynamics, which may interact further with scar formation related to surgical procedures. Cardiovascular magnetic resonance (CMR) has become an important diagnostic imaging modality in the long-term management of CHD patients. It is the gold standard technique to assess ventricular volumes and systolic function. Besides this, advanced CMR techniques allow the acquisition of more detailed information about myocardial architecture, ventricular mechanics, and fibrosis. The left ventricle (LV) and right ventricle have unique myocardial architecture that underpins their mechanics; however, this becomes disorganized under conditions of volume and pressure overload. CMR diffusion tensor imaging is able to interrogate non-invasively the principal alignments of microstructures in the left ventricular wall. Myocardial tissue tagging (displacement encoding using stimulated echoes) and feature tracking are CMR techniques that can be used to examine the deformation and strain of the myocardium in CHD, whereas 3D feature tracking can assess the twisting motion of the LV chamber. Late gadolinium enhancement imaging and more recently T1 mapping can help in detecting fibrotic myocardial changes and evolve our understanding of the pathophysiology of CHD patients. This review not only gives an overview about available or emerging CMR techniques for assessing myocardial mechanics and fibrosis but it also describes their clinical value and how they can be used to detect abnormalities in myocardial architecture and mechanics in CHD patients.

Heart Failure in Pediatric Patients With Congenital Heart Disease

Heart failure (HF) is a complex clinical syndrome resulting from diverse primary and secondary causes and shared pathways of disease progression, correlating with substantial mortality, morbidity, and cost. HF in children is most commonly attributable to coexistent congenital heart disease, with different risks depending on the specific type of malformation. Current management and therapy for HF in children are extrapolated from treatment approaches in adults. This review discusses the causes, epidemiology, and manifestations of HF in children with congenital heart disease and presents the clinical, genetic, and molecular characteristics that are similar or distinct from adult HF. The objective of this review is to provide a framework for understanding rapidly increasing genetic and molecular information in the challenging context of detailed phenotyping. We review clinical and translational research studies of HF in congenital heart disease including at the genome, transcriptome, and epigenetic levels. Unresolved issues and directions for future study are presented.

Current Therapy for Hypoplastic Left Heart Syndrome and Related Single Ventricle Lesions

Universally fatal only 4 decades ago, the progress in the 3-stage palliation of hypoplastic left heart syndrome and related single right ventricular lesions has drastically improved the outlook for these patients. Although the stage II operation (hemi-Fontan or bidirectional Glenn) and stage III Fontan procedure have evolved into relatively low-risk operations, the stage I Norwood procedure remains one of the highest-risk and costliest common operations performed in congenital heart surgery. Yet, despite this fact, experienced centers now report hospital survivals of >90% for the Norwood procedure. This traditional 3-stage surgical palliation has seen several innovations in the past decade aimed at improving outcomes, particularly for the Norwood procedure. One significant change is a renewed interest in the right ventricle-to-pulmonary artery shunt as the source of pulmonary blood flow, rather than the modified Blalock-Taussig shunt for the Norwood. The multi-institutional Single Ventricle Reconstruction trial randomly assigned 555 patients to one or the other shunt, and these subjects continue to be followed closely as they now approach 10 years postrandomization. In addition to modifications to the Norwood procedure, the hybrid procedure, a combined catheter-based and surgical approach, avoids the Norwood procedure in the newborn period entirely. The initial hybrid procedure is then followed by a comprehensive stage II, which combines components of both the Norwood and the traditional stage II, and later completion of the Fontan. Proponents of this approach hope to improve not only short-term survival, but also potentially longer-term outcomes, such as neurodevelopment, as well. Regardless of the approach, traditional surgical staged palliation or the hybrid procedure, survivals have vastly improved, and large numbers of these patients are surviving not only through their Fontan in early childhood, but also into adolescence and young adulthood. As this population grows, it becomes increasingly important to understand the longer-term outcomes of these Fontan patients, not only in terms of survival, but also in terms of the burden of disease, neurodevelopmental outcomes, psychosocial development, and quality of life.