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

Cell Therapy Trials in Congenital Heart Disease

Dramatic evolution in medical and catheter interventions and complex surgeries to treat children with congenital heart disease (CHD) has led to a growing number of patients with a multitude of long-term complications associated with morbidity and mortality. Heart failure in patients with hypoplastic left heart syndrome predicated by functional single ventricle lesions is associated with an increase in CHD prevalence and remains a significant challenge. Pathophysiological mechanisms contributing to the progression of CHD, including single ventricle lesions and dilated cardiomyopathy, and adult heart disease may inevitably differ. Although therapeutic options for advanced cardiac failure are restricted to heart transplantation or mechanical circulatory support, there is a strong impetus to develop novel therapeutic strategies. As lower vertebrates, such as the newt and zebrafish, have a remarkable ability to replace lost cardiac tissue, this intrinsic self-repair machinery at the early postnatal stage in mice was confirmed by partial ventricular resection. Although the underlying mechanistic insights might differ among the species, mammalian heart regeneration occurs even in humans, with the highest degree occurring in early childhood and gradually declining with age in adulthood, suggesting the advantage of stem cell therapy to ameliorate ventricular dysfunction in patients with CHD. Although effective clinical translation by a variety of stem cells in adult heart disease remains inconclusive with respect to the improvement of cardiac function, case reports and clinical trials based on stem cell therapies in patients with CHD may be invaluable for the next stage of therapeutic development. Dissecting the differential mechanisms underlying progressive ventricular dysfunction in children and adults may lead us to identify a novel regenerative therapy. Future regenerative technologies to treat patients with CHD are exciting prospects for heart regeneration in general practice.

Femoral Vein Homograft as Right Ventricle to Pulmonary Artery Conduit in Stage 1 Norwood Operation

BACKGROUND

The polytetrafluoroethylene tube used as right ventricle to pulmonary artery conduit in the stage 1 Norwood operation is associated with risks of suboptimal branch pulmonary artery growth, thrombosis, free insufficiency, and long-term right ventricular dysfunction. Our experience with use of valved femoral vein homograft as right ventricle to pulmonary artery conduit is described.

METHODS

Between June 2012 and December 2015, 15 neonates with hypoplastic left heart syndrome or complex single ventricle underwent stage 1 Norwood operation with valved segment of femoral vein homograft as right ventricle to pulmonary artery conduit. The median age at surgery was 3 days and the mean weight was 3 kg. The size of the femoral vein homograft was 5 mm in 8 patients and 6 mm in 7 patients.

RESULTS

There was no hospital or interstage mortality. Fourteen patients underwent Glenn operation, and 6 have undergone Fontan operation to date. The median Nakata index at pre-Glenn catheterization was 262 mm²/m² (interquartile range: 121 to 422 mm²/m²). No patient had thrombosis of conduit. Most femoral vein conduits remained competent in the first month after stage 1 Norwood operation, although most became incompetent by 3 months. Catheter intervention on the conduit was necessary in 7 patients. Right ventricular function was preserved in most patients at follow-up.

CONCLUSIONS

The use of femoral vein homograft as right ventricle to pulmonary artery conduit in the Norwood operation is safe and associated with good pulmonary artery growth and preserved ventricular function. Balloon dilation of the conduit may be necessary during the interstage period.

Utility of a standardized postcardiopulmonary bypass epicardial echocardiography protocol for stage I Norwood palliation

OBJECTIVE

Stage 1 Norwood palliation is one of the highest risk procedures in congenital cardiac surgery. Patients with superior technical performance scores have more favorable outcomes. Intraoperative epicardial echocardiography may allow the surgeon to address residual lesions prior to leaving the operating room, resulting in improved technical performance. The ability of intraoperative epicardial echocardiography to visualize the relevant anatomy and its association with outcomes is not known.

DESIGN

A standardized intraoperative epicardial echocardiography protocol was developed and performed at the conclusion of Stage 1 Norwood palliation. Data pertaining to visualization of relevant anatomy, and comparison of intraoperative echocardiogram findings with other postoperative investigations was performed. Clinical outcomes, including technical performance, were collected. A historical cohort who received either no echocardiogram or a nonstandardized examination was used as a comparison group.

RESULTS

Thirty on-protocol and 30 preprotocol patients, 22 of whom had a nonstandardized intraoperative epicardial echocardiogram, were studied. Compared with preprotocol, visualization of the relevant anatomy was significantly increased for the Damus-Kaye-Stansel anastomosis (93% vs. 68% P = .03) and branch pulmonary arteries (70% vs. 36%, P = .02). One residual lesion requiring immediate operative reintervention was diagnosed in the preprotocol group. There were 5 patients in each cohort with residual lesions during the postoperative hospitalization that were not appreciated on the intraoperative echocardiogram. Technical performance, rates of reintervention and clinical outcomes were not significantly different between the two groups.

CONCLUSIONS

Intraoperative epicardial echocardiography is technically feasible and increases visualization of the relevant anatomy. Larger investigations may be warranted to determine if there is clinical benefit to such an approach.

Intracoronary Cardiac Progenitor Cells in Single Ventricle Physiology: The PERSEUS (Cardiac Progenitor Cell Infusion to Treat Univentricular Heart Disease) Randomized Phase 2 Trial

RATIONALE

Patients with single ventricle physiology are at high risk of mortality resulting from ventricular dysfunction. The preliminary results of the phase 1 trial showed that cardiosphere-derived cells (CDCs) may be effective against congenital heart failure.

OBJECTIVE

To determine whether intracoronary delivery of autologous CDCs improves cardiac function in patients with single ventricle physiology.

METHODS AND RESULTS

We conducted a phase 2 randomized controlled study to assign in a 1:1 ratio 41 patients who had single ventricle physiology undergoing stage 2 or 3 palliation to receive intracoronary infusion of CDCs 4 to 9 weeks after surgery or staged reconstruction alone (study A). The primary outcome measure was to assess improvement in cardiac function at 3-month follow-up. Four months after palliation, controls had an alternative option to receive late CDC infusion on request (study B). Secondary outcomes included ventricular function, heart failure status, somatic growth, and health-related quality of life after a 12-month observation. At 3 months, the absolute changes in ventricular function were significantly greater in the CDC-treated group than in the controls (+6.4% [SD, 5.5] versus +1.3% [SD, 3.7]; P=0.003). In study B, a late CDC infusion in 17 controls increased the ventricular function at 3 months compared with that at baseline (38.8% [SD, 7.7] versus 34.8% [SD, 7.4]; P<0.0001). At 1 year, overall CDC infusion was associated with improved ventricular function (41.4% [SD, 6.6] versus 35.0% [SD, 8.2]; P<0.0001) and volumes (P<0.001), somatic growth (P<0.0001) with increased trophic factors production, such as insulin-like growth factor-1 and hepatocyte growth factor, and quality of life, along with a reduced heart failure status (P<0.0001) and cardiac fibrosis (P=0.014) relative to baseline.

CONCLUSIONS

Intracoronary infusion of CDCs after staged palliation favorably affected cardiac function by reverse remodeling in patients with single ventricle physiology. This impact may improve heart failure status, somatic growth, and quality of life in patients and reduce parenting stress for their families.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01829750.

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.

Hypoplastic Left Heart Syndrome: Exploring a Paradigm Shift in Favor of Surgery

We hypothesized that enthusiasm for surgery increased for infants with hypoplastic left heart syndrome (HLHS) at Columbia University Medical Center (CUMC) between 1995 and 2012. We sought to identify factors that engendered this paradigm shift. Confidential surveys were distributed to providers at CUMC in 1995 and 2012 to measure enthusiasm for surgical intervention for HLHS. Surgical preference scores are presented as median [interquartile range]. Surveys were completed by 99/176 providers (56 % response rate) in 1995 and 153/267 (57 %) in 2012. The median surgical preference score for infants with HLHS increased from 35 [25-45] in 1995 to 45 [35-50] in 2012, P < 0.001. 53 %, 95 % CI [42, 64] of respondents recommended surgical intervention for a ward of the court in 1995 compared to 81 % [73, 89] in 2012, P < 0.001. In 2012, 64 % [53, 75] of respondents were more likely to recommend surgery than 10 years prior. The percentage of respondents who saw good outcomes following three-stage repair increased from 49 % [38, 60] in 1995 to 84 % [78, 90] in 2012, P < 0.001. The majority believed that parents should have the option of comfort care, 91 % [85, 97] in 1995 and 85 % [79, 91] in 2012, P = 0.06. In both eras, prematurity and additional surgical problems dissuaded providers from recommending surgical intervention. Despite the fact that most providers have seen good outcomes and now recommend surgery for infants with HLHS, the majority of providers still believe that the option of comfort care should be available to families.

Phosphodiesterase Inhibitor-Based Vasodilation Improves Oxygen Delivery and Clinical Outcomes Following Stage 1 Palliation

BACKGROUND

Systemic vasodilation using α-receptor blockade has been shown to decrease the incidence of postoperative cardiac arrest following stage 1 palliation (S1P), primarily when utilizing the modified Blalock-Taussig shunt. We studied the effects of a protocol in which milrinone was primarily used to lower systemic vascular resistance (SVR) following S1P using the right ventricular to pulmonary artery shunt, measuring its effects on oxygen delivery (DO₂) profiles and clinical outcomes. We also correlated Fick-based assessments of DO₂ with commonly used surrogate measures.

METHODS AND RESULTS

Neonates undergoing S1P were treated according to best clinical judgment prior to (n=32) and following (n=24) implementation of a protocol that guided operative, anesthetic, and postoperative management, particularly as it related to SVR. A majority of the subjects (n=51) received a modified right ventricular to pulmonary artery shunt. In a subset of these patients (n=21), oxygen consumption (VO₂) was measured and used to calculate SVR, DO₂, and oxygen debt. Neonates treated with the protocol had significantly lower SVR (P=0.02), serum lactate (P<0.001), and Sa-vO₂ difference (P<0.001) and a lower incidence of CPR requiring extracorporeal membrane oxygenation (E-CPR, P=0.02) within the first 72 postoperative hours. DO₂ was closely associated with SVR (r²=0.78) but correlated poorly with arterial (SaO₂) and venous (SvO₂) oxyhemoglobin concentrations, the Sa-vO₂ difference, and blood pressure.

CONCLUSIONS

A vasodilator protocol utilizing milrinone following S1P effectively decreased SVR, improved serum lactate, and decreased postoperative cardiac arrest. DO₂ correlated more closely with SVR than with Sa-vO₂ difference, highlighting the importance of measuring VO₂ in this population.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02184169.

Intracoronary Stem Cell Delivery to the Right Ventricle: A Preclinical Study

Clinical protocols for stem cell-based therapies are currently under development for patients with hypoplastic left heart syndrome. An ideal cell delivery method should have minimal safety risks and provide a wide distribution of cells to the nonischemic right ventricle (RV). However, the optimal strategy for stem cell delivery to the RV has yet to be explored in a preclinical model, necessary for a hypoplastic left heart syndrome trial. Human c-kit⁺ cardiac stem cells (CSCs) were delivered to healthy Yorkshire swine through the proximal right coronary artery with a stop and reflow technique. The effect of premedication with antiarrhythmic (AA) medications in this model was retrospectively reviewed, with the primary outcome of survival 2 hours after infusion. A group underwent CSC delivery to the RV without prophylactic AA medication (no AA, n = 7), whereas the second group was premedicated with a loading dose and intravenous infusion of amiodarone and lidocaine (AA, n = 13). Cardiac biopsies were obtained from each chamber to ascertain the biodistribution of CSCs. Survival was significantly greater in the prophylactic AA group compared with the group without AA (13/13 [100%] vs 1/7 [14.3%], P < 0.0001). Cardiac arrest during balloon inflation was the cause of death in each of the nonmedicated animals. In the premedicated group, 9 (69.2%) pigs experienced transient ST segment changes in the precordial leads during CSC delivery, which resolved spontaneously. Most c-kit⁺ CSCs were distributed to lateral segments of the RV free wall, consistent with the anatomical course of the right coronary artery (lateral RV, 19.2 ± 1.5 CSCs/field of view vs medial RV, 10.4 ± 1.3 CSCs/field of view, P < 0.0001). Few c-kit⁺ CSCs were identified in the right atrium, septum, or left ventricle. Prophylactic infusion of AA enhances survival in swine undergoing intracoronary delivery of human c-kit⁺ CSCs to the RV. Additionally, intracoronary delivery results in a limited biodistribution of c-kit⁺ CSCs within the RV. Human clinical protocols can be optimized by requiring infusion of AA medications before cell delivery.

Hypoplastic Left Heart Syndrome and Other Shunt-Dependent Single Ventricles

OBJECTIVES

In this review, we discuss the pathophysiology, treatment, and outcomes of patients with the hypoplastic left heart syndrome and other single ventricle variants prior to and following surgery.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

Patients with shunted single ventricle physiology are at increased risk for acute hemodynamic decompensation owing to the increased myocardial workload, the dynamic balance between systemic and pulmonary circulations, and the potential for shunt obstruction. Understanding of the physiology and anticipatory management are critical to prevent hemodynamic compromise and cardiac arrest.

Right ventricular morphology and function following stage I palliation with a modified Blalock-Taussig shunt versus a right ventricle-to-pulmonary artery conduit

OBJECTIVES

The Norwood procedure for hypoplastic left heart syndrome (HLHS) is performed either via a right ventricle-to-pulmonary artery (RVPA) conduit or a modified Blalock–Taussig (MBT) shunt. Cardiac magnetic resonance (CMR) data was used to assess the effects of the RVPA conduit on ventricular shape and function through a computational analysis of anatomy and assessment of indices of strain.

METHODS

A retrospective analysis of 93 CMR scans of subjects with HLHS was performed (59 with MBT shunt, 34 with RVPA conduit), incorporating data at varying stages of surgery from two congenital centres. Longitudinal and short-axis cine images were used to create a computational cardiac atlas and assess global strain.

RESULTS

Those receiving an RVPA conduit had significant differences (P< 0.0001) in the shape of the RV corresponding to increased ventricular dilatation (P = 0.001) and increased sphericity (P = 0.006). Differences were evident only following completion of stage II surgery. Despite preserved ejection fraction in both groups, functional strain in the RVPA conduit group compared with that in the MBT shunt group was reduced across multiple ventricular axes, including a reduced systolic longitudinal strain rate (P< 0.0001), reduced diastolic longitudinal strain rate (P = 0.0001) and reduced midventricular systolic circumferential strain (P < 0.0001).

CONCLUSIONS

Computational modelling analysis reveals differences in ventricular remodelling in patients with HLHS undergoing an RVPA conduit insertion with focal scarring and volume loading leading to decreased functional markers of strain. The need for continued surveillance is warranted, as deleterious effects may not become apparent until later years.

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.

Myocardial Fibrosis in Congenital Heart Disease

Myocardial fibrosis is common in patients with congenital heart disease (CHD) and has been associated with arrhythmias, decreased functional status, and adverse ventricular mechanics. There are multiple types of myocardial fibrosis that occur in response to different pathophysiologic stimuli. Recent advances in imaging technology have made detection and quantification of the types of myocardial fibrosis possible. In this review, we describe the pathophysiology of myocardial fibrosis, examine the imaging techniques used to evaluate fibrosis, and discuss the relationship between myocardial fibrosis and clinical outcomes in CHD. (Circ J 2016; 80: 1300-1307).

Selective Use of the Blalock-Taussig Shunt and Right Ventricle-to-Pulmonary Artery Conduit During the Norwood Procedure

Background:

The single ventricle reconstruction trial showed better one-year transplant-free survival for the right ventricle-to-pulmonary artery (RV-to-PA) conduit over the modified Blalock-Taussig shunt (mBTS) at Norwood operation. However, concerns remain about the long-term effects of a neonatal ventriculotomy. In our institution, we have used specific selection criteria for the use of mBTS in the Norwood operation.

Methods:

We reviewed 122 consecutive neonates undergoing the Norwood procedure from December 2006 to December 2013. We used the following criteria to select our source of pulmonary blood flow: (1) presence of a dominant morphologic left ventricle; (2) presence of antegrade blood in an ascending aorta that is greater than 3 mm; and (3) presence of significant large “crossing coronaries” on ventricle. All patients who met any of the above 3 criteria underwent an mBTS while the remaining patients underwent an RV-to-PA conduit.

Results:

Seventy-five (61.5%) patients had the RV-to-PA conduit and 47 (38.5%) patients had an mBTS. The overall surgical mortality was 9%. Mean follow-up interval was 23.5 months. Actuarial transplant-free survival was similar at 12, 24, 36, and 48 months in both the mBTS group and the RV-to-PA conduit group. In the RV-to-PA conduit group, actuarial transplant-free survival was 73% at 12 months, 71% at 24 months, 71% at 36 months, and 67% at 48 months, while in the mBTS group, actuarial transplant-free survival was 82% at 12 months, 75% at 24 months, 75% at 36 months, and 75% at 48 months.

Conclusion:

Our selection criteria for mBTS have allowed us to obtain equivalent transplant-free survival at 12, 24, 36, and 48 months when compared to the RV-to-PA conduit group.

Maladaptive aortic properties after the Norwood procedure: An angiographic analysis of the Pediatric Heart Network Single Ventricle Reconstruction Trial

OBJECTIVES

Aortic arch reconstruction in children with single ventricle lesions may predispose to circulatory inefficiency and maladaptive physiology leading to increased myocardial workload. We sought to describe neoaortic anatomy and physiology, risk factors for abnormalities, and impact on right ventricular function in patients with single right ventricle lesions after arch reconstruction.

METHODS

Prestage II aortic angiograms from the Pediatric Heart Network Single Ventricle Reconstruction trial were analyzed to define arch geometry (Romanesque [normal], crenel [elongated], or gothic [angular]), indexed neoaortic dimensions, and distensibility. Comparisons were made with 50 single-ventricle controls without prior arch reconstruction. Factors associated with ascending neoaortic dilation, reduced distensibility, and decreased ventricular function on the 14-month echocardiogram were evaluated using univariate and multivariable logistic regression.

RESULTS

Interpretable angiograms were available for 326 of 389 subjects (84%). Compared with controls, study subjects more often demonstrated abnormal arch geometry (67% vs 22%, P < .01) and had increased ascending neoaortic dilation (Z score 3.8 ± 2.2 vs 2.6 ± 2.0, P < .01) and reduced distensibility index (2.2 ± 1.9 vs 8.0 ± 3.8, P < .01). Adjusted odds of neoaortic dilation were increased in subjects with gothic arch geometry (odds ratio [OR], 3.2 vs crenel geometry, P < .01) and a right ventricle-pulmonary artery shunt (OR, 3.4 vs Blalock-Taussig shunt, P < .01) but were decreased in subjects with aortic atresia (OR, 0.7 vs stenosis, P < .01) and those with recoarctation (OR, 0.3 vs no recoarctation, P = .04). No demographic, anatomic, or surgical factors predicted reduced distensibility. Neither dilation nor distensibility predicted reduced right ventricular function.

CONCLUSIONS

After Norwood surgery, the reconstructed neoaorta demonstrates abnormal anatomy and physiology. Further study is needed to evaluate the longer-term impact of these features.

Rationale and methodology of a collaborative learning project in congenital cardiac care

BACKGROUND

Collaborative learning is a technique through which individuals or teams learn together by capitalizing on one another's knowledge, skills, resources, experience, and ideas. Clinicians providing congenital cardiac care may benefit from collaborative learning given the complexity of the patient population and team approach to patient care.

RATIONALE AND DEVELOPMENT

Industrial system engineers first performed broad-based time-motion and process analyses of congenital cardiac care programs at 5 Pediatric Heart Network core centers. Rotating multidisciplinary team site visits to each center were completed to facilitate deep learning and information exchange. Through monthly conference calls and an in-person meeting, we determined that duration of mechanical ventilation following infant cardiac surgery was one key variation that could impact a number of clinical outcomes. This was underscored by one participating center's practice of early extubation in the majority of its patients. A consensus clinical practice guideline using collaborative learning was developed and implemented by multidisciplinary teams from the same 5 centers. The 1-year prospective initiative was completed in May 2015, and data analysis is under way.

CONCLUSION

Collaborative learning that uses multidisciplinary team site visits and information sharing allows for rapid structured fact-finding and dissemination of expertise among institutions. System modeling and machine learning approaches objectively identify and prioritize focused areas for guideline development. The collaborative learning framework can potentially be applied to other components of congenital cardiac care and provide a complement to randomized clinical trials as a method to rapidly inform and improve the care of children with congenital heart disease.

Early catheterization after initiation of extracorporeal membrane oxygenation support in children is associated with improved survival

OBJECTIVES

The study evaluated the institutional experience with cardiac catheterization on extracorporeal membrane oxygenation (ECMO) support.

BACKGROUND

There is scant literature on the outcomes of catheterization on ECMO.

METHODS

A retrospective review was performed of all children who underwent catheterization on ECMO from 2003 to 2013. Patients were categorized as cardiomyopathy (CM) or congenital heart disease (CHD).

RESULTS

During the study period, 215 children were placed on cardiac ECMO. Of these, 29.8% underwent 75 catheterization procedures while on ECMO support. The median age of the cohort was 1.5 months (range 0 days -16.7 years) and the median weight was 3.9 kg (2.2-63.1 kg). CM patients constituted 18.8% of the cohort and all of them underwent atrial septoplasty (an atrial septal stent in 7/12 and balloon atrial septoplasty or septostomy in 5). The survival to hospital discharge rate was 83% and the transplant-free survival rate was 58.3%. CHD patients constituted 81.2% of the cohort. In this group, transcatheter interventions were performed in 40.4% and subsequent surgical interventions in 40.4%. Survival to hospital discharge rate was 34.6% and transplant free survival rate was 32.7%. Overall, 76.7% underwent transcatheter or surgical interventions. The major catheterization complication rate was 6.7%. The mean ECMO-to-catheterization time was 1.6 days for survivors and 3.5 days for non-survivors (P = 0.034). Survival to discharge was better for the CM group compared to the CHD group (P = 0.01). Among CHD, survival was better with transcatheter interventions compared to no interventions or surgical interventions (P < 0.001).

CONCLUSIONS

Cardiac catheterization and transcatheter interventions on ECMO can be performed with low rate of complications. Catheterization was associated with high rate of interventions. Better survival to hospital discharge was associated with transcatheter interventions, earlier performance of catheterization after ECMO and diagnosis of CM. © 2016 Wiley Periodicals, Inc.

Preoperative Stabilization of Infants With Hypoplastic Left Heart Syndrome Before Stage I Palliation

Hypoplastic left heart syndrome is a severe form of congenital heart disease that results in single-ventricle physiology. Although surgical palliation in infants with this syndrome is widely agreed on in practice, variation occurs in both surgical and medical management. Perinatal factors that affect preoperative management include the subtype of the syndrome and the patient’s birth weight, gestational age, and genetic abnormalities. The general aspects of perioperative stabilization and management are monitoring, use of vasoactive infusions, ventilatory support, and nutrition. Management strategies for balancing single-ventricle physiology are aimed at addressing the 3 major causes of desaturation: diminished pulmonary blood flow, low mixed venous oxygen saturation, and pulmonary venous desaturation.

Ring-reinforced Sano right ventricular to pulmonary artery conduit at Norwood stage I

Reinterventions for proximal conduit obstruction or on the pulmonary arteries are frequent after Sano-modified stage I Norwood palliation of hypoplastic left heart syndrome. We report our experience with a modified Sano stage I, in which the right ventricle-to-pulmonary artery (PA) conduit used is reinforced by external rings to avoid collapse, and the conduit is inserted into the right ventricle through a limited ventriculotomy and 'dunked' into the ventricular cavity. In our experience, this modification was associated with fewer reinterventions or complications with the proximal anastomosis (P = 0.046 and 0.004), improved PA pulse pressure (9.1 ± 4.1 vs 4.8 ± 3.8 mmHg in controls, P < 0.001) and Nakata index (213 ± 76 vs 134 ± 68 mm(2)/m(2) in controls, P < 0.0001), although overall survival to a median of 20 months was not significantly different from controls. Right ventricular function at stage II-bidirectional Glen was marginally better in patients with the modified Sano conduit, however not to a significant level. Further evaluation of late ventricular function is currently ongoing.

Impact of initial Norwood shunt type on young hypoplastic left heart syndrome patients listed for heart transplant: A multi-institutional study

BACKGROUND

Pulmonary blood flow during Stage 1 (Norwood) palliation for hypoplastic left heart syndrome (HLHS) is achieved via modified Blalock-Taussig shunt (MBT) or right ventricle to pulmonary artery conduit (RVPA). Controversy exists regarding the differential impact of shunt type on outcome among those who require transplantation early in life. In this study we explored waitlist and post-transplant outcomes within this sub-population stratified by shunt type.

METHODS

Eligible patients were enrolled through the Pediatric Heart Transplant Study (PHTS) database. Patients included those listed for heart transplantation at 1 of 35 participating centers, all of whom were <6 years of age and with a diagnosis of HLHS (and variants) status post Stage 1 palliation with MBT or RVPA. Standard risk factors for death were analyzed using multivariable hazards modeling.

RESULTS

Between 2010 and 2013, 190 patients were identified. Compared with the RVPA group (n = 111), the MBT group (n = 79) was less likely to have undergone a Glenn palliation (41% vs 73%, p < 0.001), were younger at listing (median age 1.3 vs 1.8 years, p = 0.05), had lower median weight (7.9 vs 9.4 kg, p = 0.02), and were more likely to be mechanically ventilated at listing (35% vs 22%, p = 0.04). There were no significant differences in median waitlist time (1.7 vs 2.6 months, p = 0.2) or rate of transplantation (61% vs 60%, p = 1.0). Among waitlisted patients, 3-month survival was less for MBT compared with RVPA patients (74% vs 91%, p = 0.02). Patients who had not yet achieved Glenn palliation before listing had lower waitlist 3-month survival (76% vs 90%, p = 0.02). In MBT infants <1 year old, there was a trend toward improved survival in those with Glenn palliation compared to those without (100% vs 68%, p = 0.08). Early post-transplant mortality rates were similar between the RVPA and MBT groups (p = 0.4) with overall survival 84% at 1 year.

CONCLUSIONS

Among HLHS patients, the need for transplant before Glenn palliation is associated with poorer waitlist survival. Waitlist survival is poorer in the MBT group, with this difference driven by pre-Glenn MBT infants. Post-transplant outcomes were unaffected by shunt type.

Factors affecting Fontan length of stay: Results from the Single Ventricle Reconstruction trial

BACKGROUND

In the Single Ventricle Reconstruction trial, infants with hypoplastic left heart syndrome (HLHS) who received a right-ventricle-to-pulmonary-artery shunt (RVPAS) versus a modified Blalock-Taussig shunt (MBTS) had lower early postoperative mortality, but more complications at 14 months. We explored the effect of shunt type and other patient, medical, and surgical factors on postoperative length of stay (LOS) after the Fontan operation.

METHODS

Fontan postoperative course was ascertained from medical record review. Cox proportional hazards modeling was used to identify factors associated with LOS.

RESULTS

Of 327 subjects who underwent Fontan, 323 were analyzed (1 death, 1 biventricular repair, 2 with missing data). Median age and weight at Fontan were 2.8 years (interquartile range [IQR]: 2.3, 3.4) and 12.7 kg (IQR: 11.4, 14.1), respectively. Fontan type was extracardiac in 55% and lateral tunnel in 45%; 87% were fenestrated. The RVPAS and MBTS subjects had similar LOS (median 11 days [IQR: 9, 18] vs 10 days [IQR: 9, 13]; P = .23). Independent risk factors for longer LOS were treatment center (P < .01), LOS at stage II (hazard ratio [HR] 1.02 for each additional day; P < .01), and pre-Fontan complications (HR 1.03 for each additional complication; P = .04). Use of deep hypothermic circulatory arrest at Fontan (HR 0.64; P = .02) was independently associated with shorter LOS. When center was excluded from the model, pre-Fontan complications and use of circulatory arrest were no longer significant; instead, older age at stage II (HR 1.08 for each additional month; P = .01) predicted longer LOS. In 254 subjects who had a pre-Fontan echocardiogram, at least moderate tricuspid regurgitation was independently associated with longer LOS, both with center (HR 1.72; P < .01) and without center in the model (HR 1.49; P = .02).

CONCLUSIONS

In this multicenter prospective cohort of subjects with HLHS, Norwood shunt type was not associated with Fontan LOS. Rather, global measures of earlier medical complexity indicate greater likelihood of longer LOS after the Fontan operation.

Long-term progression and survival following Norwood Single Ventricle Reconstruction

PURPOSE OF REVIEW

Much data exist concerning Norwood discharge mortality. Less is known about late survival. Examining the available data in light of the Single Ventricle Reconstruction trial is insightful as focus shifts toward long-term survival.

RECENT FINDINGS

Data from 2000 to 2001 demonstrated approximately 40-50% 10-year survival, 30-40% or less between 10 and 15 years. The shape of the curves was characteristic; the majority of deaths within the first year, followed by a late constant phase. Publications from 2001 to 2005 suggested that various combinations of technical and perioperative modifications allowed hospital discharge survivals as high as 90-94%. As results matured (2005-2010) a consistent message was that, although the shape of the newer curves was similar (highest hazard in the first 1 year), higher hospital survival shifted the later phase to yield better long-term survival (70-85% between 5 and 10 years). Some emphasized right ventricle-based shunts as a 'cause' of improving results. Since 2010, the Single Ventricle Reconstruction trial has matured and has increasingly shifted opinion away from the right ventricle shunt as a 'cause' of improved results. The survival of the right ventricle shunt group is slightly higher at 3 years, but the 1-year statistical significance has been lost and the two groups converge. As the Single Ventricle Reconstruction study was based on the interaction between randomized shunt and survival, the secondary and other endpoint analyses must be cautiously considered.

SUMMARY

The current English-language literature suggests a 60-80% 5-10 year survival expectation. The shape of the survival curve remains; the highest hazard remains the first year before a later, stable phase is reached. Rather than a 'magic bullet' theory surrounding one technique or practice, centers have differentially adopted various combinations to optimize Norwood survival. Optimizing interstage I survival is a challenge to further increase the percentage of patients reaching the late, stable phase.

Stem cell therapy for CHD: towards translation

Stem cell therapy has the optimistic goal of regenerating the myocardium as defined by re-growth of lost or destroyed myocardium. As applied to patients with heart failure, many confuse or limit the regenerative definition to just improving myocardial function and/or decreasing myocardial scar formation, which may not be the most important clinical outcome to achieve in this promising field of molecular medicine. Many different stem cell-based therapies have been tested and have demonstrated a safe and feasible profile in adult patients with heart failure, but with varied efficacious end points reported. Although not achieved as of yet, the encompassing goal to regenerate the heart is still believed to be within reach using these cell-based therapies in adult patients with heart failure, as the first-generation therapies are now being tested in different phases of clinical trials. Similar efforts to foster the translation of stem cell therapy to children with heart failure have, however, been limited. In this review, we aim to summarise the findings from pre-clinical models and clinical experiences to date that have focussed on the evaluation of stem cell therapy in children with heart failure. Finally, we present methodological considerations pertinent to the design of a stem cell-based trial for children with heart failure, as they represent a population of patients with very different sets of issues when compared with adult patients. As has been taught by many learned clinicians, children are not small adults!

Survival and right ventricular performance for matched children after stage-1 Norwood: Modified Blalock-Taussig shunt versus right-ventricle-to-pulmonary-artery conduit

OBJECTIVE

Early survival advantages after Norwood with right-ventricle-(RV)-to-pulmonary-artery conduit (NW-RVPA) over Norwood-operation with a Blalock-Taussig shunt (NW-BT) are offset by concerns regarding delayed RV dysfunction. We compared trends in survival, RV dysfunction, and tricuspid valve regurgitation (TR) between NW-RVPA and NW-BT for propensity-matched neonates with critical left ventricular outflow tract obstruction (LVOTO).

METHODS

In an inception cohort (2005-2014; 21 institutions), 454 neonates with critical LVOTO underwent Norwood stage 1. Propensity-score matching paired 169 NW-RVPA patients with 169 NW-BT patients. End-states were compared between NW-RVPA and NW-BT using competing-risks, multiphase, parametric, hazard analysis. Post-Norwood echocardiogram reports (n = 2993) were used to grade RV dysfunction and TR. Time-related prevalence of ≥moderate RV dysfunction and TR were characterized using nonlinear mixed-model regression, and compared between groups via multiphase, parametric models.

RESULTS

Overall 6-year survival was better after NW-RVPA (70%) versus NW-BT (55%; P < .001). Additionally, transplant-free survival during this time was better after NW-RVPA (64%) versus NW-BT (53%; P = .004). Overall prevalence of ≥moderate RV dysfunction reached 11% within 3 months post-Norwood. During this time, RV dysfunction after NW-BT was 16% versus 6% after NW-RVPA (P = .02), and coincided temporally with an increased early hazard for death. For survivors, late RV dysfunction was <5% and was not different between groups (P = .36). Overall prevalence of ≥moderate TR reached 13% at 2 years post-Norwood and was increased after NW-BT (16%) versus NW-RVPA (11%; P = .003). Late TR was similar between groups.

CONCLUSIONS

Among propensity-score-matched neonates with critical LVOTO, NW-RVPA offers superior 6-year survival with no greater prevalence of RV dysfunction or TR than conventional NW-BT operations.

Impact of initial norwood shunt type on right ventricular deformation: the single ventricle reconstruction trial

BACKGROUND

The Single Ventricle Reconstruction trial demonstrated a transplantation-free survival advantage at 12-month follow-up for patients with right ventricle-pulmonary artery shunts (RVPAS) with the Norwood procedure compared with modified Blalock-Taussig shunts but similar survival and decreased global right ventricular (RV) function on longer term follow-up. The impact of the required ventriculotomy for the RVPAS remains unknown. The aim of this study was to compare echocardiography-derived RV deformation indices after stage 2 procedures in survivors with single RV anomalies enrolled in the Single Ventricle Reconstruction trial.

METHODS

Global and regional RV systolic longitudinal and circumferential strain and strain rate, ejection fraction, and short-axis percentage fractional area change were all derived by speckle-tracking echocardiography from protocol echocardiograms obtained at 14.3 ± 1.2 months. Student t tests or Wilcoxon rank sum tests were used to compare groups.

RESULTS

The cohort included 275 subjects (129 in the modified Blalock-Taussig shunt group and 146 in the RVPAS group). Longitudinal deformation could be quantified in 214 subjects (78%) and circumferential measures in 182 subjects (66%). RV ejection fraction and percentage fractional area change did not differ between groups. There were no significant differences between groups for global or regional longitudinal deformation. Circumferential indices showed abnormalities in deformation in the RVPAS group, with decreased global circumferential strain (P = .05), strain rate (P = .09), and anterior regional strain rate (P = .07) that approached statistical significance.

CONCLUSIONS

RV myocardial deformation at 14 months, after stage 2 procedures, was not significantly altered by the type of initial shunt placed. However, abnormal trends were appreciated in circumferential deformation for the RVPAS group in the area of ventriculotomy that may represent early myocardial dysfunction. These data provide a basis for longer term RV deformation assessment in survivors after Norwood procedures.