Biventricular Conversion After Single Ventricle Palliation in Patients With Small Left Heart Structures: Short-Term Outcomes

Surgical outcome of the borderline hypoplastic left ventricle: impact of the left ventricle rehabilitation strategy

OBJECTIVE

This study aims to assess the surgical outcome of borderline hypoplastic left ventricle before and after the induction of the left ventricle rehabilitation strategy.

METHODS

A retrospective review investigated patients with borderline hypoplastic left ventricle who underwent surgical intervention between 2012 and 2022. The patient cohort was stratified into two groups based on the initiation of left ventricle rehabilitation: an early-era group (E group, 2012-2017) and a late-era group (L group, 2018-2022). Left ventricle rehabilitation was defined as palliation combined with other procedures aimed at promoting left ventricular growth such as restriction of atrial septal defect, relief of inflow/outflow obstructive lesions, and resection of endocardial fibroelastosis.

RESULTS

A total of 58 patients were included. Primary diagnosis included 12 hypoplastic left heart syndromes, 11 critical aortic valve stenosis, and others. A total of 9 patients underwent left ventricle rehabilitation, 8 of whom underwent restriction of atrial septal defect. As for clinical outcomes, 9 of 23 patients achieved biventricular repair in the E group, whereas in the L group, 27 of 35 patients achieved biventricular repair (39% vs. 77%, p = 0.004). Mortality did not differ statistically between the two groups (log-rank test p = 0.182). As for the changes after left ventricle rehabilitation, left ventricular growth was observed in 8 of 9 patients. The left ventricular end-diastolic volume index (from 11.4 to 30.1 ml/m2, p = 0.017) and left ventricular apex-to-right ventricular apex ratio (from 86 to 106 %, p = 0.014) significantly increased after left ventricle rehabilitation.

CONCLUSIONS

The introduction of the left ventricle rehabilitation strategy resulted in an increased proportion of patients achieving biventricular repair without a concomitant increase in mortality. Left ventricle rehabilitation was associated with enhanced left ventricular growth and the formation of a well-defined left ventricle apex. Our study underscores the significance of left ventricle rehabilitation strategies facilitating successful biventricular repair. The data suggest establishing restrictive atrial communication may be a key factor in promoting left ventricular growth.

Comparison of definitive approaches for conotruncal defects following bidirectional Glenn procedure

BACKGROUND

Staged repair is common for complex conotruncal defects, often involving bidirectional Glenn (BDG) procedure. Following the cavopulmonary shunt, both Fontan completion and biventricular conversion (BiVC) serve as definitive approaches. The optimal strategy remains controversial.

METHODS

The baseline, perioperative and follow-up data were obtained for all paediatric patients with conotruncal defects who underwent BDG procedure as palliation in Fuwai Hospital from 2013 to 2022. Patients with single ventricle were excluded. The primary outcome was mortality. The secondary outcome was reintervention, including any cardiovascular surgeries and non-diagnostic catheterisations.

RESULTS

A total of 232 patients were included in the cohort, with 142 underwent Fontan (61.2%) and 90 underwent BiVC (38.8%). The median interstage period from BDG to the definitive procedure was 3.83 years (IQR: 2.72-5.42) in the overall cohort, 3.62 years (IQR: 2.57-5.15) in the Fontan group and 4.15 years (IQR: 3.05-6.13) in the BiVC group (p=0.03). The in-hospital outcomes favoured the Fontan group, including duration of cardiopulmonary bypass, aortic cross-clamp, mechanical ventilation and intensive care unit stay. Postoperative mortality was generally low and comparable, as was the reintervention rate (HR=1.42, 95% CI: 0.708 to 2.85, p=0.32). The left ventricular size was smaller at baseline and within the normal range at follow-up for both Fontan and BiVC groups; however, it was significantly larger with BiVC at follow-up.

CONCLUSION

In paediatric patients with conotruncal heart defects who underwent BDG procedure, BiVC is a feasible option, especially for patients with certain Fontan risk factors, and are not ideal candidates for successful Fontan completion.

Borderline Ventricles: From Evaluation to Treatment

A heart with a borderline ventricle refers to a situation where there is uncertainty about whether the left or right underdeveloped ventricle can effectively support the systemic or pulmonary circulation with appropriate filling pressures and sufficient physiological reserve. Pediatric cardiologists often deal with congenital heart diseases (CHDs) associated with various degrees of hypoplasia of the left or right ventricles. To date, no specific guidelines exist, and surgical management may be extremely variable in different centers and sometimes even in the same center at different times. Thus, the choice between the single-ventricle or biventricular approach is always controversial. The aim of this review is to better define when "small is too small and large is large enough" in order to help clinicians make the decision that could potentially affect the patient's entire life.

Factors associated with morbidity, mortality, and hemodynamic failure after biventricular conversion in borderline hypoplastic left hearts

OBJECTIVE

A subset of patients with borderline hypoplastic left heart may be candidates for single to biventricular conversion, but long-term morbidity and mortality persist. Prior studies have shown conflicting results regarding the association of preoperative diastolic dysfunction and outcome, and patient selection remains challenging.

METHODS

Patients with borderline hypoplastic left heart undergoing biventricular conversion from 2005 to 2017 were included. Cox regression identified preoperative factors associated with a composite outcome of time to mortality, heart transplant, takedown to single ventricle circulation, or hemodynamic failure (defined as left ventricular end-diastolic pressure >20 mm Hg, mean pulmonary artery pressure >35 mm Hg, or pulmonary vascular resistance >6 international Woods units).

RESULTS

Among 43 patients, 20 (46%) met the outcome, with a median time to outcome of 5.2 years. On univariate analysis, endocardial fibroelastosis, lower left ventricular end-diastolic volume/body surface area (when <50 mL/m2), lower left ventricular stroke volume/body surface area (when <32 mL/m2), and lower left:right ventricular stroke volume ratio (when <0.7) were associated with outcome; higher preoperative left ventricular end-diastolic pressure was not. Multivariable analysis demonstrated that endocardial fibroelastosis (hazard ratio, 5.1, 95% confidence interval, 1.5-22.7, P = .033) and left ventricular stroke volume/body surface area 28 mL/m2 or less (hazard ratio, 4.3, 95% confidence interval, 1.5-12.3, P = .006) were independently associated with a higher hazard of the outcome. Approximately all patients (86%) with endocardial fibroelastosis and left ventricular stroke volume/body surface area 28 mL/m2 or less met the outcome compared with 10% of those without endocardial fibroelastosis and with higher stroke volume/body surface area.

CONCLUSIONS

History of endocardial fibroelastosis and smaller left ventricular stroke volume/body surface area are independent factors associated with adverse outcomes among patients with borderline hypoplastic left heart undergoing biventricular conversion. Normal preoperative left ventricular end-diastolic pressure is insufficient to reassure against diastolic dysfunction after biventricular conversion.

Therapy of Patients with Cardiac Malposition

Positional abnormalities per se do not require treatment, but in their place, the accompanying pulmonary pathology in dextroposition patients and pathophysiologic hemodynamic abnormalities resulting from multiple defects in patients with cardiac malposition should be the focus of treatment. At the time of the first presentation, treating the pathophysiologic aberrations caused by the defect complex, whether it is by improving the pulmonary blood flow or restricting it, is the first step. Some patients with simpler or single defects are amenable to surgical or transcatheter therapy and should be treated accordingly. Other associated defects should also be treated appropriately. Biventricular or univentricular repair dependent on the patient's cardiac structure should be planned. Complications in-between Fontan stages and after conclusion of Fontan surgery may occur and should be promptly diagnosed and addressed accordingly. Several other cardiac abnormalities unrelated to the initially identified heart defects may manifest in adulthood, and they should also be treated.

A Review of Biventricular Repair for the Congenital Cardiac Anesthesiologist

The management of children with a borderline ventricle has been debated for many years. The pursuit of a biventricular repair in these children aims to avoid the long-term sequelae of single ventricle palliation. There is a lack of anesthesia literature relating to the care of this complex heterogenous patient population. Anesthesiologists caring for these patients should have an understanding on the many different forms of physiology and the impact on provision of anesthesia and hemodynamic parameters, the goals of biventricular staging and completion as well as the pre-operative, intra-operative, and post-operative considerations relating to this high-risk group of patients.

Management of the Borderline Left Heart and Alternatives to Fontan

Management of borderline left heart can be divided into single ventricle and biventricular repair strategies. Recently, the strategy of left heart recruitment has been applied to select patients. Left heart recruitment strategies and alternatives to Fontan circulation are reviewed. The criteria utilized for decision-making include size and function of left heart structures as well as hemodynamics measured by cardiac catheterization.

Considerations for Biventricular Conversion of Fontan Circulation

Despite significant improvements in the management of Fontan circulation in patients with single ventricle physiology, long-term outcomes continue to be suboptimal. Conversion to biventricular circulation is increasingly gaining popularity, particularly in the subset of patients who are not ideal Fontan candidates. Meticulous image-guided planning, extensive preoperative discussions, and a team-based approach are required for successful execution of complex biventricular conversion. A segmental approach to the anatomy of the heart defect allows methodical planning of the technique of biventricular conversion. Ventricular size and function continue to be the Achilles heel of successful biventricular repair. Long-term studies comparing outcomes in patients converted to biventricular circulation to those in patients with Fontan physiology are required to appropriately tailor management approaches to an individual patient.

Biventricular Conversion for Hypoplastic Left Heart Variants: An Update

Ongoing concerns with single-ventricle palliation morbidity and poor outcomes from primary biventricular strategies for neonates with borderline left heart structures have led some centers to attempt alternative strategies to obviate the need for ultimate Fontan palliation and limit the risk to the child during the vulnerable neonatal period. In certain patients who are traditionally palliated toward single-ventricle circulation, biventricular circulation is possible. This review aims to delineate the current knowledge regarding converting certain patients with borderline left heart structures from single-ventricle palliation toward biventricular circulation.

Impact of 3D Printing on Short-Term Outcomes of Biventricular Conversion From Single Ventricular Palliation for the Complex Congenital Heart Defects

Background: Although Fontan palliation seems to be inevitable for many patients with complex congenital heart defects (CHDs), candidates with appropriate conditions could be selected for biventricular conversion. We aimed to summarize our single-center experience in patient selection, surgical strategies, and early outcomes in biventricular conversion for the complex CHD.

Methods: From April 2017 to June 2021, we reviewed 23 cases with complex CHD who underwent biventricular conversion. Patients were divided into two groups according to the development of the ventricles: balanced ventricular group (15 cases) and imbalanced ventricular group (8 cases). Early and short-term outcomes during the 30.2 months (range, 4.2–49.8 months) follow-up period were compared.

Results: The overall mortality rate was 4.3% with one death case. In the balanced ventricular group, 6 cases received 3D printing for pre-operational evaluation. One case died because of heart failure in the early postoperative period. One case received reoperation due to the obstruction of the superior vena cava. In the imbalanced ventricular group, the mean left ventricular end-diastolic volume was (33.6 ± 2.1) ml/m2, the mean left ventricular end-diastolic pressure was 9.1 ± 1.9 mmHg, and 4 cases received 3D printing. No death occurred while one case implanted a pacemaker due to a third-degree atrioventricular block. The pre-operational evaluation and surgery simulation with a 3D printing model helped to reduce bypass time in the balanced group (p &lt; 0.05), and reduced both bypass and aorta clamp time in the imbalanced group (p &lt; 0.05). All patients presented great cardiac function in the follow-up period.

Conclusion: Comprehensive evaluation, especially 3D printing technique, was conducive to finding the appropriate cases for biventricular conversion and significantly reduced surgery time. Biventricular conversion in selected patients led to promising clinical outcomes, albeit unverified long-term results.

Single Ventricle-A Comprehensive Review

In this paper, the author enumerates cardiac defects with a functionally single ventricle, summarizes single ventricle physiology, presents a summary of management strategies to address the single ventricle defects, goes over the steps of staged total cavo-pulmonary connection, cites the prevalence of inter-stage mortality, names the causes of inter-stage mortality, discusses strategies to address the inter-stage mortality, reviews post-Fontan issues, and introduces alternative approaches to Fontan circulation.

Biventricular conversion after Fontan completion: A preliminary experience

OBJECTIVE

To assess the feasibility and outcomes of biventricular conversion following takedown of Fontan circulation.

METHODS

Retrospective analysis of patients who had takedown of Fontan circulation and conversion to biventricular circulation at a single center from September 2007 to April 2020. Failing Fontan physiology was defined as Fontan circulation pressure >15 mm Hg and/or the presence of associated complications.

RESULTS

Biventricular conversion was performed in 23 patients at a median age of 10.0 (7.5-13.0) years. Indications included failing Fontan physiology in 15 (65%) and elective takedown in 8 (35%) patients. A subset of patients (n = 6) underwent procedures for staged recruitment of the nondominant ventricle before conversion. Median z score of end-diastolic volume of borderline ventricle before takedown was -2.3 (-3.3, -1.3). Hypoplastic left heart syndrome (P < .01) and sub-/aortic stenosis (P < .01) were more common in these patients. Biventricular conversion with or without staged ventricular recruitment led to a significant increase in indexed end-diastolic volume (P < .01), indexed end-systolic volume (P < .01), and ventricular mass (P < .01) of the nondominant ventricle (14 right, 9 left ventricle). There were 5 (22%) deaths (1 [4%] early death). All who underwent elective biventricular conversion survived, whereas 2-year survival rate for patients with a failing Fontan circulation was 72.7% (95% confidence interval, 37%-90%). The overall, 3-year reoperation-free survival was 86.7% (95% confidence interval, 56%-96%). Left dominant atrioventricular canal defect (P < .01) and early era of biventricular conversion (P = .02) were significant predictors for mortality.

CONCLUSIONS

A primary as well as a staged biventricular conversion is feasible in patients who have had previous Fontan procedure. Although this provides an alternative to transplantation in patients with failing Fontan, outcomes are worse in those with failing Fontan compared with elective takedown of Fontan circulation. Optimal timing needs further evaluation.

Development of a biventricular conversion program: A new paradigm

BACKGROUND

Borderline small ventricular size or technical issues precluding the use of both ventricles may lead to single ventricle palliation. Fontan complications have led some centers to look for alternatives to the traditional pathway. The objective of this study is to evaluate the essential philosophy and outcomes of a new biventricular (BiV) conversion program.

METHODS

The prospectively collected Children's Memorial Hermann Heart Institute Society of Thoracic Surgeon's Database was retrospectively reviewed between July 2017 and July 2020.

RESULTS

Thirteen patients met inclusion criteria and underwent BiV conversion during that time. The most frequent diagnosis was malposed great arteries and a ventricular septal defect (VSD) in 4 (31%) patients. Seven (54%) patients were in the first interstage, and 1 (8%) patient had already undergone a Fontan operation before their BiV conversion operation. One or more risk factors for single ventricle palliation (genetic syndrome ≥ moderate atrioventricular valve regurgitation ≥ moderate ventricular dysfunction, presence of signs of Fontan failure) were present in 3 (23%) patients. The median left ventricular end diastolic pressure increased from 5.5 mmHg (4-10 mmHg) to 10 mmHg (6-20 mmHg) postoperatively (p < .05). The right ventricular pressure (RVP) was estimated as less than half systemic in all six patients who were able to be estimated. At a median follow-up of 22.6 months (0.3-36.4 months), 12 (92%) patients are alive.

CONCLUSIONS

BiV conversion is feasible with reasonable short-term clinical outcomes. Mortality risk is low, but as seen in other studies, the risk of reintervention is high.

Left Ventricular Recruitment in Patients With Hypoplastic Left Heart Syndrome

Hypoplastic left heart complex with "borderline left ventricle" and intact ventricular septum is a clinical conundrum for the congenital heart surgeon. The choice between neonatal biventricular repair and single ventricle palliation can be challenging, and the current tools to aid in the decision-making process fail to account for the morbidity associated with intermediate and late diastolic dysfunction. Staged ventricular recruitment, consisting of valvular repair techniques, resection of endocardial fibroelastosis, atrial septal restriction, and augmentation of pulmonary blood flow, has been shown to improve left ventricular size and function culminating in eventual biventricular circulation. Despite staged ventricular recruitment, some patients cannot undergo biventricular conversion. Strategies to address these complex patients, including the "reverse" double switch, are the next frontier in biventricular repair.

Half-turned truncal switch operation after single ventricle palliation in a patient with borderline left heart hypoplasia

BACKGROUND

The optimal surgical strategy for the correction of double outlet right ventricle (DORV, transposition of the great arteries [TGA] type) or TGA with ventricular septal defect (VSD), pulmonary stenosis (PS), and borderline small left ventricle (LV) is still controversial. The half-turned truncal switch operation (HTTSO) introduced by Yamagishi and colleagues is a good option, but it is still challenging in a patient with borderline small LV. We aimed to describe our experience of a case of HTTSO conversion from single ventricle palliation.

CASE PRESENTATION

A 5-year-old girl with single ventricle physiology was referred to our hospital from Kazakhstan for a Fontan operation. At the time of birth, she was diagnosed with DORV (TGA type), PS, and situs inversus totalis, with moderate valvar and subvalvar stenosis and a relatively small LV cavity. Her LV volume was not adequate to support the systemic circulation; therefore, doctors in Kazakhstan selected the single ventricle palliation course of treatment for the infant. At 4 months of age, she underwent left-sided modified Blalock-Taussig shunt, patent ductus arteriosus ligation, and atrial septectomy. At 2 years of age, shunt takedown, left bidirectional cavopulmonary shunt, and main pulmonary artery division were performed. Annual echocardiography of the patient showed that the LV size was growing too adequately to persist with the single ventricle palliation course of treatment. Via a multidisciplinary approach, we considered her LV to be suitable for biventricular repair and HTTSO was planned. The operation and postoperative course were uneventful. The patient was discharged on postoperative day 6 and went back to Kazakhstan.

CONCLUSIONS

Based on our successful surgical outcome, in patients diagnosed with DORV (TGA type) or TGA with VSD, PS, and borderline LV, HTTSO after achieving adequate LV growth by single ventricle palliation may be considered a good alternative to conventional operations in patients at a high risk for initial biventricular repair.

Biventricular Conversion in the Borderline Hypoplastic Heart

PURPOSE OF REVIEW

The development of biventricular repair and conversion pathways for patients with borderline hypoplastic heart disease represents an area of recent inquiry and innovation. This review summarizes emerging techniques and novel treatment algorithms for borderline hypoplastic heart disease with a focus on surgical advances within the last 10 years.

RECENT FINDINGS

Many patients with borderline hypoplastic heart disease are amenable to primary biventricular repair, or biventricular conversion following single-ventricle palliation coupled with ventricular rehabilitation strategies. New insights into the potential for growth and recovery of borderline ventricles have been uncovered. However, questions remain regarding optimal patient selection and the long-term outcomes of select patient groups treated with single-ventricle palliation versus biventricular repair/conversion or transplantation. Efforts to direct a greater proportion of borderline hypoplastic heart patients towards a biventricular circulation are accelerating and represent important avenues for progress and future research in the field of congenital heart disease.

From Fontan to Anatomical Repair 16 Years Later

Decision making for univentricular or anatomical repair remains challenging in children with borderline left ventricle. Unpredictable outcomes have led many caregivers to pursue a single-ventricle strategy. We describe 2 cases of patients with borderline left ventricle initially palliated with univentricular strategy followed by very late conversion to anatomical repair 4 and 16 years later. Anatomical conversion should be considered for these patients even many years later. During the first palliation stages, hemodynamic conditions preserving the potential for growth of the left ventricle should be maintained.

Congenital Cardiac Defects That Are Borderline Candidates for Biventricular Repair

This article discusses congenital heart defects that are marginal candidates for biventricular repair and highlights the anatomic considerations upon which the surgical decision is based. Specifically, the article reviews the importance of capacitance and compliance of the ventricles and their associated atrioventricular valves. For each of the defects discussed, the imaging modalities used to diagnose a marginal ventricle are reviewed and the surgical decision-making process is outlined. The article also reviews immediate postoperative treatment of these patients and when to consider biventricular repair of a marginal lesion to be a failure.

Hemodynamic assessment of atrial septal defects

Atrial septal defect (ASD) is one of the most common congenital cardiac anomalies. ASD can present as an isolated lesion in an otherwise normal heart or in association with other congenital heart conditions. Regardless of the type of ASD, the direction and degree of shunting across the communication is mainly determined by the difference in compliance between the right and left ventricle. Hemodynamics in children is characterized by left-to-right shunting, dilated right heart structures and normal pulmonary artery pressures (PAP). Patients diagnosed at adult age often present with complications related to long-standing volume overload such as pulmonary artery hypertension and right and left ventricular dysfunction. Diagnostic catheterization is usually not indicated unless there is suggestion of pulmonary hypertension on echocardiography. In older patients and/or in those with ventricular dysfunction, measurement of left heart pressures during temporary balloon occlusion is recommended prior to device closure as it may not be tolerated. In ASD associated with other congenital malformations, shunting degree and direction will depend upon underlying condition. Restrictive ASD can result in significant hemodynamic compromise in neonates with conditions such as hypoplastic left heart syndrome (HLHS) and transposition of the great arteries (TGA). In most cases, hemodynamics can be estimated with echocardiography only.

Clinical and Hemodynamic Results After Conversion from Single to Biventricular Circulation After Fetal Aortic Stenosis Intervention

At our institution a multidisciplinary team has performed fetal aortic valvuloplasty (FAV) for severe aortic stenosis with evolving hypoplastic left heart syndrome with high technical success rates. Measurement of postnatal success has been biventricular circulation (BC). Postnatal survival for patients after FAV who achieved a BC appears encouraging. However, there are limited late clinical and hemodynamic outcomes in this cohort and there is concern for diastolic dysfunction. We reviewed all patients with FAV at our institution who initially underwent single ventricle palliation and subsequently BC, as this is likely the subset at high-risk for poor outcomes. Clinical, imaging, and surgical data were collected. Two of 7 patients (29%) died within 16 months of BC, and 1 patient has been listed for transplant. Diastolic dysfunction was common and progressive with median left ventricular end diastolic pressure of 12 mm Hg before BC, and increasing to 22 mm Hg for survivors at last follow-up. Left ventricular size was adequate with all patients reaching a left ventricular end diastolic volume (LVEDV) z score in the normal or elevated range. Presence and severity of residual valve lesions decreased over time secondary to a median of 6 interventions (range 3 to 10), either surgical or cath-based, performed for these 7 patients during the study period. In conclusion, clinical outcomes are concerning for this high-risk group. Diastolic dysfunction is persistent and progressive despite anatomic interventions and adequate left ventricular growth. The main contributing factor to poor outcomes may be intrinsic myocardial dysfunction and primordial pathology. Achievement of a BC after FAV may not be an appropriate measure of success.

Assessing the borderline ventricle in a term infant: combining imaging and physiology to establish the right course

PURPOSE OF REVIEW

The purpose of this review is to describe the challenges associated with the diagnosis and treatment of children with borderline ventricles. A borderline ventricle is one in which there is concern that it will not be able to support its circulation. If a biventricular repair is attempted and fails, outcome is often poor. Thus, this early decision is important.

RECENT FINDINGS

For the borderline right ventricle, options to add an additional source of pulmonary blood flow make the surgical strategy a bit more flexible than for patients with a borderline left ventricle. In general, outcome for a so-called one and one-half ventricle repair are generally good, though the long-term outcome and the effects of this physiology on lifelong exercise performance and quality of life remain to be seen. For the small left ventricle, often multiple surgeries are required to 'force' blood into the left ventricle and potentially help it grow. Though this strategy is successful in some, in others it results in significant residual cardiac issues including pulmonary hypertension.

SUMMARY

Determining whether a patient will be better off in the long term with a marginal biventricular repair versus a Fontan circulation remains one of the most difficult problems in the field of pediatric cardiology and cardiac surgery.

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.

Recent advances in managing septal defects: ventricular septal defects and atrioventricular septal defects

This review discusses the management of ventricular septal defects (VSDs) and atrioventricular septal defects (AVSDs). There are several types of VSDs: perimembranous, supracristal, atrioventricular septal, and muscular. The indications for closure are moderate to large VSDs with enlarged left atrium and left ventricle or elevated pulmonary artery pressure (or both) and a pulmonary-to-systemic flow ratio greater than 2:1. Surgical closure is recommended for large perimembranous VSDs, supracristal VSDs, and VSDs with aortic valve prolapse. Large muscular VSDs may be closed by percutaneous techniques. A large number of devices have been used in the past for VSD occlusion, but currently Amplatzer Muscular VSD Occluder is the only device approved by the US Food and Drug Administration for clinical use. A hybrid approach may be used for large muscular VSDs in small babies. Timely intervention to prevent pulmonary vascular obstructive disease (PVOD) is germane in the management of these babies. There are several types of AVSDs: partial, transitional, intermediate, and complete. Complete AVSDs are also classified as balanced and unbalanced. All intermediate and complete balanced AVSDs require surgical correction, and early repair is needed to prevent the onset of PVOD. Surgical correction with closure of atrial septal defect and VSD, along with repair and reconstruction of atrioventricular valves, is recommended. Palliative pulmonary artery banding may be considered in babies weighing less than 5 kg and those with significant co-morbidities. The management of unbalanced AVSDs is more complex, and staged single-ventricle palliation is the common management strategy. However, recent data suggest that achieving two-ventricle repair may be a better option in patients with suitable anatomy, particularly in patients in whom outcomes of single-ventricle palliation are less than optimal. The majority of treatment modes in the management of VSDs and AVSDs are safe and effective and prevent the development of PVOD and cardiac dysfunction.

Boston Children׳s Hospital Cardiovascular Program

The Cardiovascular program at Boston Children's Hospital has been characterized as a "great institution" by the editors. This designation is the result of a commitment to innovation interdisciplinary collaboration, rigorous review of results and continuous self-improvement, training the next generation, and an ability to "get the right people on the bus".

Left Ventricular Outflow Tract Obstruction: Coarctation of the Aorta, Interrupted Aortic Arch, and Borderline Left Ventricle

OBJECTIVES

The objectives of this review are to discuss the perioperative management of coarctation of the aorta, interrupted aortic arch, and the borderline left ventricle.

METHODS

MEDLINE and PubMed.

CONCLUSIONS

Successful management of systemic obstructive lesions involves a thorough evaluation of the anatomy and pathophysiology to determine the most effective management strategy.

A Review of Surgical Atrioventricular Block with Emphasis in Patients with Single Ventricle Physiology

We perceived an increased incidence of surgical atrioventricular (AV) block in patients with single ventricle physiology undergoing two ventricle rehabilitation for hypoplastic left heart syndrome compared to the overall incidence of surgical AV block for our institution. Retrospective investigation of our center's data revealed a statistically significant increase in the incidence of surgical AV block in the single ventricle population and two ventricle rehabilitation population compared to the two ventricle population. Here we review the literature with respect to historic definitions, incidence, risk factors, pre- and post-op management, current indications for pacemaker placement and added cost and comorbidity associated with surgical AV block. We then offer possible strategies for decreasing the incidence of surgical AV block within both the single and two ventricle populations.

Development of an echocardiographic scoring system to predict biventricular repair in neonatal hypoplastic left heart complex

Neonates born with borderline left heart hypoplasia, or hypoplastic left heart complex, can undergo biventricular repair while those with severe left heart hypoplasia require single ventricle palliation. Deciding which patients are candidates for biventricular repair may be very difficult since there are no scoring systems to predict biventricular repair in these patients. The purpose of this study is to develop an echocardiographic scoring system capable of predicting successful biventricular repair in neonatal hypoplastic left heart complex. The study cohort consisted of twenty consecutive neonates with hypoplastic left heart complex presenting between 9/2008 and 5/2013. Multiple retrospective echocardiographic measurements of the right and left heart were performed. Six patients with significant LH hypoplasia (patent mitral and aortic valves, small left ventricle) who had undergone single ventricle repair were used to validate the scoring system. Seventeen patients underwent biventricular repair and three underwent single ventricle repair. A scoring system (2V-Score) was developed using the equation {[(MV4C/AVPSLA) ÷ (LV4C/RV4C)] + MPA}/BSA. Using a cutoff value of ≤ 16.2, a biventricular repair would have been predicted with a sensitivity of 1.0, specificity 1.0, positive predictive value 1.0, negative predictive value 1.0, area under the ROC curve 1.0, and the p value was 0.0004. The 2V-Score was more accurate than the Rhodes, CHSS, or Discriminant scores in retrospectively predicting biventricular repair in this cohort. The 2V-Score shows promise in being able to predict a successful biventricular repair in patients with hypoplastic left heart complex but requires prospective validation prior to widespread clinical application.

Fetal aortic valvuloplasty for evolving hypoplastic left heart syndrome: postnatal outcomes of the first 100 patients

BACKGROUND

Fetal aortic valvuloplasty can be performed for severe midgestation aortic stenosis in an attempt to prevent progression to hypoplastic left heart syndrome (HLHS). A subset of patients has achieved a biventricular (BV) circulation after fetal aortic valvuloplasty. The postnatal outcomes and survival of the BV patients, in comparison with those managed as HLHS, have not been reported.

METHODS AND RESULTS

We included 100 patients who underwent fetal aortic valvuloplasty for severe midgestation aortic stenosis with evolving HLHS from March 2000 to January 2013. Patients were categorized based on postnatal management as BV or HLHS. Clinical records were reviewed. Eighty-eight fetuses were live-born, and 38 had a BV circulation (31 from birth, 7 converted after initial univentricular palliation). Left-sided structures, namely aortic and mitral valve sizes and left ventricular volume, were significantly larger in the BV group at the time of birth (P<0.01). After a median follow-up of 5.4 years, freedom from cardiac death among all BV patients was 96±4% at 5 years and 84±12% at 10 years, which was better than HLHS patients (log-rank P=0.04). There was no cardiac mortality in patients with a BV circulation from birth. All but 1 of the BV patients required postnatal intervention; 42% underwent aortic or mitral valve replacement. On the most recent echocardiogram, the median left ventricular end-diastolic volume z score was +1.7 (range, -1.3 to +8.2), and 80% had normal ejection fraction.

CONCLUSIONS

Short- and intermediate-term survival among patients who underwent fetal aortic valvuloplasty and achieved a BV circulation postnatally is encouraging. However, morbidity still exists, and ongoing assessment is warranted.