Impact of right ventricle to pulmonary artery conduit on outcome of the modified Norwood procedure

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Impact of Left Ventricular Morphology on Adverse Outcomes Following Stage 1 Palliation for Hypoplastic Left Heart Syndrome: 20 Years of National Data From Sweden

Background

Hypoplastic left heart syndrome is associated with significant morbidity and mortality. We aimed to assess the influence of left ventricular morphology and choice of shunt on adverse outcome in patients with hypoplastic left heart syndrome and stage 1 palliation.

Methods and Results

This was a retrospective analysis of patients with hypoplastic left heart syndrome with stage 1 palliation between 1999 and 2018 in Sweden. Patients (n=167) were grouped based on the anatomic subtypes aortic‐mitral atresia, aortic atresia‐mitral stenosis (AA‐MS), and aortic‐mitral stenosis. The left ventricular phenotypes including globular left ventricle (Glob‐LV), miniaturized and slit‐like left ventricle (LV), and the incidence of major adverse events (MAEs) including mortality were assessed. The overall mortality and MAEs were 31% and 41%, respectively. AA‐MS (35%) was associated with both mortality (all other subtypes versus AA‐MS: interstage‐I: hazard ratio [HR], 2.7; P =0.006; overall: HR, 2.2; P =0.005) and MAEs (HR, 2.4; P =0.0009). Glob‐LV (57%), noticed in all patients with AA‐MS, 61% of patients with aortic stenosis‐mitral stenosis, and 19% of patients with aortic atresia‐mitral atresia, was associated with both mortality (all other left ventricular phenotypes versus Glob‐LV: interstage‐I: HR, 4.5; P =0.004; overall: HR, 3.4; P =0.0007) and MAEs (HR, 2.7; P =0.0007). There was no difference in mortality and MAEs between patients with AA‐MS and without AA‐MS with Glob‐LV ( P >0.15). Patients with AA‐MS (35%) or Glob‐LV (38%) palliated with a Blalock‐Taussig shunt had higher overall mortality compared with those palliated with Sano shunts, irrespective of the stage 1 palliation year (AA‐MS: HR, 2.6; P =0.04; Glob‐ LV: HR, 2.1; P =0.03).

Conclusions

Glob‐LV and AA‐MS are independent morphological risk factors for adverse short‐ and long‐ term outcome, especially if a Blalock‐Taussig shunt is used as part of stage 1 palliation. These findings are important for the clinical management of patients with hypoplastic left heart syndrome.

Proximal Pulmonary Artery Evaluation in Infants With Shunt-Dependent Pulmonary Blood Flow: Computed Tomographic Angiography Versus Transthoracic Echocardiography

Background:

Infants with shunt-dependent pulmonary blood flow are at risk for developing proximal pulmonary artery (PA) stenosis, which may result in morbidity and mortality. Transthoracic echocardiography (TTE) is the primary means of surveillance for PA narrowing but has significant limitations and has not been compared to computed tomographic angiography (CTA)–derived measurements of the proximal PA anatomy in this population.

Methods:

A retrospective chart review identified infants with shunt-dependent pulmonary blood flow who had both TTE and CTA performed <14 days apart during a five-year period. Proximal right pulmonary artery (RPA) and left pulmonary artery (LPA) diameters were measured by TTE and CTA. Pulmonary artery z-score, linear and intraclass correlation (ICC) coefficients, and Bland-Altman plots were computed.

Results:

Seventeen pairs of studies were analyzed. The TTE and CTA proximal PA diameters had moderate linear correlation and agreement ( R = 0.67, P ≤ .0001, ICC = 0.65); the RPA showed stronger correlation and agreement ( R = 0.76, P = .0004, ICC = 0.72) than the LPA (R = 0.59, P = .01, ICC = 0.59). Computed tomographic angiography detected missed PA stenosis ( Z score < −2) in five (14.7%) cases, four of which were on the LPA.

Conclusion:

In this study of infants with shunt-dependent pulmonary blood flow, TTE and CTA proximal PA diameters had only moderate correlation and agreement overall, which was worse when comparing LPA measurements. This resulted in missed PA stenosis by TTE. Computed tomographic angiography may be warranted in patients with poorly visualized PAs by TTE or suspicion for deficient pulmonary blood flow.

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.

Mathematical Analysis and Physical Profile of Blalock-Taussig Shunt and Sano Modification Procedure in Hypoplastic Left Heart Syndrome: Review of the Literature and Implications for the Anesthesiologist

The first stage of surgical treatment for hypoplastic left heart syndrome (HLHS) includes the creation of artificial systemic-to-pulmonary connections to provide pulmonary blood flow. The modified Blalock-Taussig (mBT) shunt has been the technique of choice for this procedure; however, a right ventricle-pulmonary artery (RV-PA) shunt has been introduced into clinical practice with encouraging but still conflicting outcomes when compared with the mBT shunt. The aim of this study is to explore mathematical modeling as a tool for describing physical profiles that could assist the surgical team in predicting complications related to stenosis and malfunction of grafts in an attempt to find correlations with clinical outcomes from clinical studies that compared both surgical techniques and to assist the anesthesiologist in making decisions to manage patients with this complex cardiac anatomy. Mathematical modeling to display the physical characteristics of the chosen surgical shunt is a valuable tool to predict flow patterns, shear stress, and rate distribution as well as energetic performance at the graft level and relative to ventricular efficiency. Such predictions will enable the surgical team to refine the technique so that hemodynamic complications be anticipated and prevented, and are also important for perioperative management by the anesthesia team.

Significance of low peak Doppler velocity in the proximal sano conduit in hypoplastic left heart syndrome

BACKGROUND

The Sano modification of the Norwood operation is a well-established first step palliation for hypoplastic left heart syndrome (HLHS). Theoretically, the first point of resistance to pulmonary flow should be in the proximal Sano, generating high Doppler flow velocity. Paradoxically, however, some patients have low gradients in the proximal Sano conduit. The objective of this study was to determine the hemodynamic and anatomic significance of low proximal Sano Doppler flow velocity and its clinical implications.

METHODS

Doppler-derived peak gradients in the proximal Sano conduits were measured in HLHS patients after Norwood-Sano surgery over a 4-year period and confirmed by cardiac catheterization within 2 to 4 weeks. Clinical outcomes of patients with proximal Sano gradients of 30 mm Hg or less (group 1) were compared with patients whose gradient was greater than 30 mm Hg (group 2).

RESULTS

Of the 53 patients, 21 (40%) belonged to group 1. Patients in group 1 had smaller ostial right and left pulmonary artery (PA) diameter (3.2 ± 1.2 mm versus 4.5 ± 1.8 mm, p = 0.03; and 3.4 ± 1.2 mm versus 5.6 ± 2.1 mm, p = 0.01) when compared with patients in group 2. Patients (7 of 10) who needed either balloon angioplasty of a distal Sano or proximal branch PA were from group 1 (p = 0.01). Patients in group 1 had higher rates of unintended PA interventions (33% versus 9%) and complications (48% versus 16%) compared with group 2.

CONCLUSIONS

Low peak Doppler flow velocity in the proximal Sano correlates with the presence of either distal Sano stenosis or proximal branch PA stenosis. These patients require close follow-up in the interstage period and may need earlier intervention.

A systematic review of the impact of volume of surgery and specialization in Norwood procedure

Background

The volume-outcome relationship is supposed to be stronger in high risk, low volume procedures. The aim of this systematic review is to examine the available literature on the effects of hospital and surgeon volume, specialization and regionalization on the outcomes of the Norwood procedure.

Methods

A systematic literature search was performed in Medline, Embase, and the Cochrane Library. On the basis of titles and abstracts, articles of comparative studies were obtained in full-text in case of potential relevance and assessed for eligibility according to predefined inclusion criteria. All relevant data on study design, patient characteristics, hospital volume, surgeon volume and other institutional characteristics, as well as results were extracted in standardized tables. Study selection, data extraction and critical appraisal were carried out independently by two reviewers.

Results

We included 10 studies. All but one study had an observational design. The number of analyzed patients varied from 75 to 2555. Overall, the study quality was moderate with a huge number of items with an unclear risk of bias. All studies investigating hospital volume indicated a hospital volume-outcome relationship, most of them even having significant results. The results were very heterogeneous for surgeon volume.

Conclusions

The volume-outcome relationship in the Norwood procedure can be supported. However, the magnitude of the volume effect is difficult to assess.

Impact of pre-stage II hemodynamics and pulmonary artery anatomy on 12-month outcomes in the Pediatric Heart Network Single Ventricle Reconstruction trial

OBJECTIVE

To compare the interstage cardiac catheterization hemodynamic and angiographic findings between shunt types for the Pediatric Heart Network Single Ventricle Reconstruction trial. The trial, which randomized subjects to a modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS) for the Norwood procedure, demonstrated the RVPAS was associated with a smaller pulmonary artery diameter but superior 12-month transplant-free survival.

METHODS

We analyzed the pre-stage II catheterization data for the trial subjects. The hemodynamic variables and shunt and pulmonary angiographic data were compared between shunt types; their association with 12-month transplant-free survival was also evaluated.

RESULTS

Of 549 randomized subjects, 389 underwent pre-stage II catheterization. A smaller size, lower aortic and superior vena cava saturation, and higher ventricular end-diastolic pressure were associated with worse 12-month transplant-free survival. The MBTS group had a lower coronary perfusion pressure (27 vs 32 mm Hg; P<.001) and greater pulmonary blood flow/systemic blood flow ratio (1.1 vs 1.0, P=.009). A greater pulmonary blood flow/systemic blood flow ratio increased the risk of death or transplantation only in the RVPAS group (P=.01). The MBTS group had fewer shunt (14% vs 28%, P=.004) and severe left pulmonary artery (0.7% vs 9.2%, P=.003) stenoses, larger mid-main branch pulmonary artery diameters, and greater Nakata indexes (164 vs 134, P<.001).

CONCLUSIONS

Compared with the RVPAS subjects, the MBTS subjects had more hemodynamic abnormalities related to shunt physiology, and the RVPAS subjects had more shunt or pulmonary obstruction of a severe degree and inferior pulmonary artery growth at pre-stage II catheterization. A lower body surface area, greater ventricular end-diastolic pressure, and lower superior vena cava saturation were associated with worse 12-month transplant-free survival.

Short-term outcome comparison of Norwood procedures with right ventricle to pulmonary artery conduit versus modified Blalock-Taussig shunt: A meta-analysis

A small number of nonrandomized and retrospective studies have compared outcomes of classical Norwood procedures for hypoplasticleft-heart syndrome and single ventricle lesions involving a Blalock-Taussig (BT) shunt to the modified procedure using a right ventricle to pulmonary artery conduit. Some of these studies reported data for the same outcomes and a meta-analysis was done to analyze pooled outcomes comparing in-hospital mortality, interstage mortality, cardiopulmonary bypass time, systolic and diastolic blood pressures 24 h postoperatively, length of intensive care and hospital stay, and need for postoperative extracorporeal membrane oxygenation. Right ventricle to pulmonary artery conduit was associated with an insignificant reduction of in-hospital mortality (odds ratio, 0.674, 95% confidence interval, 0.367 to 1.238), and in the length of hospital stay. There were significant reductions in cardiopulmonary bypass time, length of intensive care unit stay, and need for postoperative extracorporeal membrane oxygenation, postoperative ventilation times, and interstage mortality (odds ratio, 0.191, confidence interval, 0.0620 to 0.587). There was a significant increase in diastolic blood pressure and an insignificant increase in systolic blood pressure 24 h postoperatively. This pooled analysis demonstrates potential advantages associated with the right ventricle to pulmonary artery conduit when compared to the modified BT shunt in palliation and demonstrates the need for large randomized controlled trials that compare a number of outcomes in both procedures.

Impact of pharmacotherapy on interstage mortality and weight gain in children with single ventricle

OBJECTIVE.: Infants with single ventricle physiology have a high mortality and poor somatic growth during the interstage period. We retrospectively assessed the impact of pharmacotherapy in this population using a multicenter database. DESIGN AND RESULTS.: Records for 395 patients (63.5% boys) with single ventricle were obtained from the National Pediatric Cardiology Quality Improvement Collaborative registry. Median of five medications were prescribed per patient at discharge after stage 1 palliation (interquartile range 3 to 6); the most common medications being aspirin (95.7%), diuretics (90.4%), angiotensin convertase enzyme inhibitors (37.7%), proton pump inhibitors (33.4%), H2 receptor blockers (30.6%), and digoxin (27.6%). Interstage mortality was 9.4%. Digoxin use was associated with lower risk of death (P =.03) on univariable analysis, however no single medication was an independent predictor on regression analysis. Change in weight-for-age z-score was studied as outcome of somatic growth with 36.3% patients showing a decrease during the interstage period. Total number of medications prescribed to a patient showed a negative correlation with the interstage change in z-score (r = -0.19, P =.002). On univariable comparisons, use of metoclopramide and lansoprazole were associated with decreased z-score (P =.004 and.041, respectively) although linear regression failed to identify any agent as independent predictor. CONCLUSIONS.: Children with single ventricle have high mortality and a profound medication burden. No individual medication is independently associated with better survival or weight gain during interstage period. Despite widespread use, proton pump inhibitors and prokinetic agents are not associated with better outcomes and may be associated with poor growth.

Size of the right ventricle-to-pulmonary artery conduit impacts mid-term outcome after the Norwood procedure in patients weighing less than 3 kg

OBJECTIVE

The optimal shunt size for patients who have the Norwood operation with a right ventricle-to-pulmonary artery conduit is controversial. The goal of this study is to compare outcomes of 2 shunt sizes in this population.

METHODS

Between 2002 and 2010, 75 consecutive patients diagnosed with hypoplastic left heart syndrome and its variants underwent the Norwood procedure with a right ventricle-to-pulmonary artery conduit. The outcomes of 20 neonates weighing <3 kg were analyzed.

RESULTS

The cumulative 30-day stage 1 survival [corrected] was 97% (95% confidence interval, 88%-99%) for all patients (73/75), 20 of whom weighed <3 kg. Nine patients had a 6-mm (group 1) and 11 patients had a 5-mm (group 2) right ventricle-to-pulmonary artery conduit. Thirty-day stage 1 survival was 88% (8/9) in group 1 and 90% (10/11) in group 2 (P = .88). The central pulmonary artery confluence size at prebidirectional cavopulmonary shunt catheterization was 4.5 ± 1.2 mm in group 1 and 2.5 ± 1.0 mm in group 2 (P = .009). The mean transpulmonary gradient was higher in group 2 (7.8 ± 3.1 mm Hg vs 4.2 ± 1.9 mm Hg; P = .036). The incidence of pulmonary artery intervention was 16% (1/7) in group 1 and 75% (6/8) in group 2 (P = .030). Survival rate at 6 months was 66% (6/9) in group 1 and 70% (7/10) in group 2 (P = .89).

CONCLUSIONS

Use of a 6-mm right ventricle-to-pulmonary artery conduit showed better central pulmonary artery growth and less need for pulmonary artery intervention in the authors' experience.

Effect of endovascular stenting of right ventricle to pulmonary artery conduit stenosis in infants with hypoplastic left heart syndrome on stage II outcomes

There is growing awareness that the Norwood procedure with the Sano modification is prone to early right ventricular to pulmonary artery (RV-PA) conduit stenosis resulting in systemic oxygen desaturation, increased interstage morbidity, and death. We report our experience with endovascular stent placement for conduit stenosis and compare the outcomes at stage II surgery between stented and nonstented infants. The medical records of all patients with hypoplastic left heart syndrome who received an RV-PA conduit at Norwood palliation from May 2005 to January 2010 were reviewed. The preoperative anatomy, demographics, operative variables, and outcomes pertaining to the Norwood and subsequent stage II surgeries were obtained and compared between stented and nonstented infants. The pre- and post-stent oxygen saturation, stenosis location, type and number of stents implanted, concomitant interventions, procedure-related complications, and reinterventions were collected. Of the 66 infants who underwent the Norwood procedure with RV-PA conduit modification, 16 (24%) received stents. The anatomy, demographics, and outcome variables after the Norwood procedure were similar between the stented and nonstented infants. The age at catheterization was 93 ± 48 days, and the weight was 4.9 ± 1.2 kg. The oxygen saturation increased from 66 ± 9% before intervention to 82 ± 6% immediately after stenting (p <0.0001). No interstage surgical shunt revisions were performed in either group. Age, weight, pre-stage II echocardiographic variables, oxygen saturation, and operative and outcome variables, including mortality, were similar between the 2 groups. In conclusion, endovascular stent placement for RV-PA conduit stenosis after the Norwood procedure leads to improved systemic oxygen levels and prevents early performance of stage II surgery without compromising stage II outcomes.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Neonatal surgical reconstruction and peri-operative care for hypoplastic left heart syndrome: current strategies

The management of newborns with hypoplastic left heart syndrome has changed significantly over the past three decades, with an associated dramatic improvement in outcomes. The aim of this paper is to discuss current peri-operative and palliative surgical strategies. Owing to the fact that comparative outcomes for these strategies have been addressed in a limited number of prospective trials and extractions from multi-centred databases, the primary focus of this review is descriptive.

Norwood procedure with non-valved right ventricle to pulmonary artery shunt improves ventricular energetics despite the presence of diastolic regurgitation: a theoretical analysis

When the Norwood procedure is conducted for the hypoplastic left heart syndrome using a non-valved right ventricle (RV) to pulmonary artery (PA) shunt, diastolic regurgitation from PA to RV may have an adverse effect on postoperative hemodynamics. In this study, we examined the impact of the diastolic regurgitation on ventricular energetics by computational analysis using a combination of a time-varying elastance chamber model and a modified three-element Windkessel vascular model. This study revealed that use of the valved or non-valved RV-PA shunt eliminated pulmonary over-circulation which was observed when using the systemic to pulmonary artery shunt (modified Blalock-Taussig shunt). Although the valved RV-PA shunt improved pulmonary blood supply and consequently increased pulmonary artery flow and oxygen saturation compared to the non-valved RV-PA shunt, the non-valved RV-PA shunt improved ventricular energetics in spite of the presence of PA to RV regurgitation.

Second-Stage Palliation After Bilateral Pulmonary Artery Bands for HLHS and its Variants—Which is Better, Modified Norwood or Norwood Plus Bidirectional Glenn?

Background. The purpose of this study was to evaluate the surgical outcomes and pulmonary artery (PA) development associated with a new strategy wherein the modified Norwood (N) procedure is performed at 1-2 months after bilateral pulmonary artery banding (PAB). Methods. Between January 2008 and February 2010, 16 patients underwent Norwood-type operation after previous bilateral PAB. For analysis, patients were divided into two groups. Group I (n = 11) underwent modified Norwood procedure with either right modified Blalock Taussig (RMBT) shunt (n = 4) or right ventricle to pulmonary artery (RV-PA) conduit (n = 7). Group II (n = 5) underwent Norwood procedure plus bidirectional Glenn anastomosis. Diagnoses were hypoplastic left heart syndrome in 6 and its variants in 10. Results. There was no surgical death and no late death. Pulmonary artery interventions were performed at the time of the Norwood procedure in 27% in Group I and in 100% in Group II (p < 0.05). Additional PA interventions were performed during the period of follow-up in 4 cases in Group I (36.4%), and in 4 cases in Group II (80.0%). Additional Blalock Taussig shunts were performed in 7 patients, resulting in significant increase in PA index. In all, four patients have reached total cavopulmonary connection, and one has undergone biventricular repair. Eight patients in Group I and one patient in II Group reached bidirectional Glenn anastomosis. In Gp II, two patients showed LPA narrowing or obstruction with PA index of 80 ± 12 mm2/m2. Conclusions. Regarding the second-stage palliation after bilateral PAB, modified Norwood procedure with either RMBT or RV-PA conduit has some advantages compared with Norwood plus BDG with respect to subsequent pulmonary artery development. Additional BT shunt may contribute to PA development, even in the patients with Norwood procedure with RV-PA conduit.

Prenatal diagnosis of hypoplastic left heart syndrome in current era

We sought to evaluate the relation of a prenatal diagnosis (preDx) with morbidity and mortality during the initial hospitalization in a contemporary cohort of patients with hypoplastic left heart syndrome (HLHS). A retrospective study of patients with HLHS presenting from 1999 to 2010 was performed. Patients with genetic disorders or a gestational age <34 weeks or who had intentionally received comfort care only were excluded. Of the 81 patients meeting the study criteria, 49 had a preDx and 32 were diagnosed postnatally (postDx). Birth weight (median 3.0 vs 3.4 kg; p = 0.007) and gestational age (median 38 vs 39 weeks; p <0.001) were lower in the preDx than in the postDx patients. Preoperatively, the postDx patients were intubated more frequently (97% vs 71%, p = 0.004) and ventilated longer (median 96 vs 24 hours, p = 0.005) than the preDx patients. They also had more preoperative acidosis, multiorgan failure, tricuspid valve regurgitation, and right ventricular dysfunction. Of the 73 patients undergoing surgery, no difference in survival was seen between the preDx and postDx groups (91% vs 89%). The median duration of postoperative ventilation was 7 days and the median length of stay was 36 days for the 66 survivors, with no difference between the 2 groups. Postoperative morbidities, including chylothorax and infection, were also similar in the preDx and postDx patients. No studied preoperative factor was associated with death, duration of postoperative ventilation, or length of stay. In conclusion, our recent experience has shown that preDx of HLHS was not associated with a survival advantage, fewer postoperative complications, or shorter length of stay. Improved preoperative status was observed in the preDx patients; however, they were born earlier with a lower birthweight. What effect these factors might have on longer term morbidity remains unknown.

Can Randomized Clinical Trials Impact the Surgical Approach for Hypoplastic Left Heart Syndrome?

The Eighth International Conference of the Pediatric Cardiac Intensive Care Society was held in Miami, Florida, December 8 to 11, 2010. The program included a session dedicated to the management of hypoplastic left heart syndrome (HLHS), with particular emphasis on the innovations that have led to contemporary schemes of management and the role of clinical trials in the evolution and acceptance of these strategies. An invited panel of experts reviewed the historical evolution of staged surgical reconstruction, the randomized clinical trials that have been undertaken thus far, and the extent to which these have, or have not, influenced individual and institutional approaches to management of HLHS.

Celiac artery flow pattern in infants with single right ventricle following the Norwood procedure with a modified Blalock-Taussig or right ventricle to pulmonary artery shunt

A potential advantage of the right ventricle to pulmonary artery versus modified Blalock-Taussig shunt in patients undergoing the Norwood procedure is limitation of diastolic runoff from the systemic to pulmonary circulation. We evaluated mesenteric flow patterns and gastrointestinal outcomes following the Norwood procedure associated with either shunt type. Patients randomized to a right ventricle to pulmonary artery versus modified Blalock-Taussig shunt in the Pediatric Heart Network Single Ventricle Reconstruction Trial at centers participating in this ancillary study were eligible for inclusion; those with active necrotizing enterocolitis, sepsis, or end-organ dysfunction were excluded. Celiac artery flow characteristics and gastrointestinal outcomes were collected at discharge. Forty-four patients (five centers) were included. Median age at surgery was 5 days [interquartile range (IQR) = 4-8 days]. Median celiac artery resistive index (an indicator of resistance to perfusion) was higher in the modified Blalock-Taussig shunt group (n = 19) versus the right ventricle to pulmonary artery shunt group (n = 25) [1.00 (IQR = 0.84-1.14) vs. 0.82 (IQR = 0.74-1.00), p = 0.02]. There was no difference in interstage weight gain, necrotizing enterocolitis, or feeding intolerance episodes between the groups. The celiac artery resistive index was higher in patients with the modified Blalock-Taussig shunt versus the right ventricle to pulmonary artery shunt but was not associated with measured gastrointestinal outcomes.

Stage II palliation of hypoplastic left heart syndrome without cardiopulmonary bypass

OBJECTIVES

Bidirectional cavopulmonary anastomosis has been performed without cardiopulmonary bypass for some single-ventricle heart defects. Limited data are available for the outcomes of off-pump bidirectional cavopulmonary anastomosis in infants with hypoplastic left heart syndrome. The purpose of this study is to determine the early outcomes for stage II palliation of hypoplastic left heart syndrome without cardiopulmonary bypass.

METHODS

This is a retrospective review of infants having surgical palliation of hypoplastic left heart syndrome from April 2003 to March 2010 at a single institution.

RESULTS

Seventy-five infants had a modified Norwood procedure, 65 with a right ventricle-pulmonary artery conduit, 10 with an aortopulmonary shunt, 2 with atrioventricular valve repair, and 3 with extracorporeal life support. Sixty-eight patients had hypoplastic left heart syndrome or one of its variants, and 7 had other single-ventricle lesions. There were 2 stage I deaths. Stage I survival was 97% (95% confidence interval, 88%-99%). Another 5 infants succumbed in the interstage period. Of the 68 stage I and interstage survivors, 61 had bidirectional cavopulmonary anastomoses, 20 without cardiopulmonary bypass. Median age was 6 months (range, 4-13 months), and median weight was 6.1 kg (range, 5.2-9.0 kg). There were no conversions to cardiopulmonary bypass when off-pump bidirectional cavopulmonary anastomosis was attempted. There were no hospital deaths. Median ventilation duration was 10 hours (range, 6-18 hours), and length of stay was 5 days (range, 4-9 days). Follow-up was available on all infants at a median duration of 17 months (range, 3-43 months), with no unplanned reinterventions.

CONCLUSIONS

Bidirectional cavopulmonary anastomosis without the use of cardiopulmonary bypass can be performed safely and with low mortality for selected infants with hypoplastic left heart syndrome. Midterm to long-term outcomes remain to be determined.

Perioperative monitoring in high-risk infants after stage 1 palliation of univentricular congenital heart disease

OBJECTIVE

Survival of high-risk patients with univentricular heart disease after Norwood palliation is reduced. We hypothesized that early goal-directed monitoring with venous oximetry and near-infrared spectroscopy would offset their increased vulnerability and improve survival.

METHODS

A prospective database of patients undergoing stage 1 palliation was used to assess differences in outcomes across risk groups in the setting of a comprehensive, goal-directed monitoring program. High-risk criteria included gestational age 35 weeks or less, birth weight less than 2.5 kg, and additional cardiac or extracardiac anomalies. Outcomes included survival to defined end points and measures of postoperative support.

RESULTS

From September 2000 to September 2008, 162 patients underwent stage 1 palliation: 28% (45/162) high-risk and 72% (117/162) standard-risk patients. Lesions other than hypoplastic left heart syndrome were more common among high-risk patients (38%, 17/45, vs 15%, 18/117, P = .003). Operative survival was not statistically different(87%, 39/45, high risk vs 95%, 111/117, standard risk, P = .1). High-risk patients were more likely to receive inpatient treatment until stage 2 palliation (24%, 11/45, vs 10%, 12/117, P = .001) and had lower 1-year survival (78% vs 93%, P = .01) and survival to date (71% vs 92%, P = .001).

CONCLUSIONS

Intensive monitoring partially offset biologic vulnerability of high-risk patients, helping attain comparable early outcomes. Vulnerability persisted throughout the interstage period, however, and increased mortality beyond cavopulmonary shunt was seen only among high-risk patients. Although enhanced monitoring reduced early mortality, high resource use and attrition after stage 2 palliation suggest an ongoing need to evaluate our current palliative strategy for this subset of patients.

Comparison of Norwood shunt types: do the outcomes differ 6 years later?

BACKGROUND

A modification to the Norwood procedure involving a right ventricle-to-pulmonary artery (RV-PA) shunt may improve early postoperative outcomes. Concerns remain about the effect of the right ventriculotomy required with this shunt on long-term ventricular function.

METHODS

Between January 2000 and April 2005, 76 patients underwent the Norwood procedure, 35 with a modified Blalock-Taussig shunt (mBTS) and 41 with a RV-PA shunt. Patients were monitored until death or September 1, 2009, with an average follow-up of 6.8 years. Cardiac catheterization, echocardiograms, perioperative Fontan courses, and need for cardiac transplantation were compared between groups.

RESULTS

Cumulative survival was 63% (22 of 35) in the mBTS group vs 78% (32 of 41) in the RV-PA group (p = 0.14). Pre-Fontan echocardiography revealed poorer ventricular function in RV-PA patients (p = 0.03). Cardiac transplantation was required in 6 of 32 (19%) patients with a prior RV-PA shunt vs 1 of 23 (4%) in the mBTS group (p = 0.06). This results in an almost identical cumulative transplant-free survival between groups; 60% (21 of 35) in the mBTS group and 63% (26 of 41) in the RV-PA group (p = 0.95).

CONCLUSIONS

Neither shunt offers a clear survival advantage through an average follow-up of 6.8 years. The RV-PA shunt results in impaired late ventricular function that may result in an increased need for cardiac transplantation.

Comparison of shunt types in the Norwood procedure for single-ventricle lesions

BACKGROUND

The Norwood procedure with a modified Blalock-Taussig (MBT) shunt, the first palliative stage for single-ventricle lesions with systemic outflow obstruction, is associated with high mortality. The right ventricle-pulmonary artery (RVPA) shunt may improve coronary flow but requires a ventriculotomy. We compared the two shunts in infants with hypoplastic heart syndrome or related anomalies.

METHODS

Infants undergoing the Norwood procedure were randomly assigned to the MBT shunt (275 infants) or the RVPA shunt (274 infants) at 15 North American centers. The primary outcome was death or cardiac transplantation 12 months after randomization. Secondary outcomes included unintended cardiovascular interventions and right ventricular size and function at 14 months and transplantation-free survival until the last subject reached 14 months of age.

RESULTS

Transplantation-free survival 12 months after randomization was higher with the RVPA shunt than with the MBT shunt (74% vs. 64%, P=0.01). However, the RVPA shunt group had more unintended interventions (P=0.003) and complications (P=0.002). Right ventricular size and function at the age of 14 months and the rate of nonfatal serious adverse events at the age of 12 months were similar in the two groups. Data collected over a mean (+/-SD) follow-up period of 32+/-11 months showed a nonsignificant difference in transplantation-free survival between the two groups (P=0.06). On nonproportional-hazards analysis, the size of the treatment effect differed before and after 12 months (P=0.02).

CONCLUSIONS

In children undergoing the Norwood procedure, transplantation-free survival at 12 months was better with the RVPA shunt than with the MBT shunt. After 12 months, available data showed no significant difference in transplantation-free survival between the two groups. (ClinicalTrials.gov number, NCT00115934.)

Right Ventricle-to-Pulmonary Artery Shunt in Norwood Procedure: Early Results

The aim of this study was to evaluate experience and predictors of early mortality in patients with hypoplastic left heart syndrome (HLHS)–type defects undergoing Norwood procedure (NP) with right ventricle-to-pulmonary artery (RV-PA) shunt. Between 2001 and 2009, a consecutive series of 229 children with HLHS-type single ventricle underwent NP with application of RV-PA shunt. Demographic, echocardiographic, and clinical perioperative data were retrospectively analyzed. The mean duration of follow-up of survivors was 4.5 ± 2.1 years (60 days to 8.1 years). Follow-up was complete for 92.1% of patients. Major early postoperative complications included sepsis/generalized infection in 40 (17.5%), pericardial effusion in 9 (3.9%), and wound infection in 8 (3.5%). The early (30-day) survival was 87.8% (n = 201). In the late postoperative period, 12 (5.9%) died. Early nonsurvivors were more frequently older than 14 days ( P = .045) at initial surgery, had lower operative weight ( P = .024), had more frequent associated cardiac ( P < .001) and/or extracardiac anomalies ( P < .001), and were more likely to have a restrictive interatrial communication before operation ( P = .024). Use of the right RV-PA shunt has helped to mitigate some previously described predictors of early death after NP. Longer follow-up will be required to determine whether the RV-PA shunt modification confers an important survival benefit.

Acute interventions for stenosed right ventricle-pulmonary artery conduit following the right-sided modification of Norwood-Sano procedure

INTRODUCTION

The Norwood stage 1 procedure was modified by Sano with right ventricle-pulmonary artery (RV-PA) conduit replacing BT shunt. In our institution, this has been further modified by placing the conduit from the RV outflow tract to the right side of the neo-aorta.

PATIENTS AND METHODS

Between April 2002 and October 2008, 227 modified Norwood procedures were performed. Eighteen had the Sano modification with the conduit to the left of the neo-aorta whereas 209 had the right-sided modification, which is the study population. A total of 18 (8.6%) patients presented with cyanosis due to conduit stenosis with median age 4 months and median weight 6.3 kg.

RESULTS

Twelve patients underwent transcatheter stent placement in stenosed RV-PA conduit. A total of 16 coronary stents were implanted in 12 patients with 4 patients each receiving 2 stents. The mean saturations increased from 60% to 74%. There was one late mortality which was non-procedure related. Five patients treated with surgical take down of the RV-PA conduit and creation of a cavo-pulmonary shunt, whilst one patient had replacement of RV-PA conduit. There were no early postoperative deaths. The mean saturations improved from 54% to 75%.

CONCLUSIONS

The RV-PA conduit stenosis is a life-threatening complication after the modified Norwood Stage I procedure. This may require urgent surgery to replace the conduit or to perform a cavo-pulmonary shunt but as an alternative, transcatheter stent placement can be used with equal effectiveness and with a low risk of complications. The catheter approach is less invasive and the results show that it is an excellent option to relieve the stenosis even in the right-sided RV-PA conduit.

Development of the pulmonary arteries after the Norwood procedure: comparison between Blalock-Taussig shunt and right ventricular-pulmonary artery conduit

BACKGROUND

The Norwood-Sano procedure for hypoplastic left heart syndrome (HLHS) has been associated with improved postoperative hemodynamics and outcome. This study compared the effect of a Blalock-Taussig shunt with right ventricular-pulmonary artery (RV-PA) conduit before bidirectional Glenn on the development of the PAs.

METHODS

Between January 2000 and June 2007, 42 patients with HLHS underwent bidirectional Glenn: 19 (mean age, 7 +/- 1.5 months) had a Blalock-Taussig shunt (3.5 mm in 15; and 4 mm in 4); 23 patients (mean age, 5 +/- 1 month) had RV-PA conduit (5-mm tube). Patients underwent postoperative cardiac catheterization and echocardiograms.

RESULTS

Total PA (Nakata) index was 192 +/- 10 mm2/m2 in the Blalock-Taussig group and 238 +/- 18 mm2/m2 in the RV-PA conduit group (p = 0.03). In the RV-PA conduit patients, the left and right PAs had comparable diameters. In the Blalock-Taussig group, the left PA was smaller than the right (p = 0.02). The mean PA pressure at the end of the operation was 14 +/- 2 mm Hg in the Blalock-Taussig group and 11 +/-1 mm Hg in the RV-PA conduit group (p = 0.06). Persistent pleural effusion occurred in 4 Blalock-Taussig patients (21%) and in 1 (4%) with RV-PA conduit (p < 0.05). Postoperative arterial oxygen saturation was 80% +/- 2% in the RV-PA conduit group and 74% +/- 2% in the Blalock-Taussig group (p < 0.05).

CONCLUSIONS

The Norwood procedure with RV-PA conduit may have favorable effects on the development of the PA due to even distribution of pulmonary blood flow.

Two-Year Survival and Mental and Psychomotor Outcomes After the Norwood Procedure

Background— The Norwood procedure for stage 1 palliation of hypoplastic left heart syndrome is performed with either the modified Blalock-Taussig (MBTS) or the right ventricle–to–pulmonary artery (RVPA) shunt. In our institution, surgical practice changed from use of the MBTS to use of the RVPA shunt in 2002. We analyzed survival and mental and psychomotor outcomes of the 2 consecutive surgical eras.

Methods and Results— Between September 1996 and July 2005, 94 neonates with hypoplastic left heart syndrome underwent the Norwood procedure. Patients were recruited as neonates and followed up prospectively. Health, mental, and psychomotor outcomes (Bayley Scales of Infant Development-II) were assessed at 2 years. The study subjects were from the Norwood-MBTS era (n=62; 1996 to 2002) or the Norwood-RVPA era (n=32; 2002 to 2005). In the MBTS era, early and 2-year mortality rates were 23% (14/62) and 52% (32/62); the mean (SD) mental and psychomotor developmental indices were 79 (18) and 67 (19). In the RVPA era, early and 2-year mortality rates were 6% (2/32) and 19% (6/32); the mean (SD) mental and psychomotor developmental indices were 85 (18) and 78 (18). The 2-year mortality rate ( P =0.002) and the psychomotor developmental index ( P =0.029) were improved in the more recent surgical era. On multivariable Cox regression analysis, postoperative highest serum lactate independently predicted 2-year mortality in the MBTS and RVPA eras.

Conclusions— Analysis of 2 consecutive surgical eras of hypoplastic left heart syndrome patients undergoing the Norwood procedure showed a significant improvement in 2-year survival and psychomotor development in the more recent era. Adverse neurodevelopmental outcome in this patient population remains a concern.

Stage I palliation for hypoplastic left heart syndrome: Is a right ventricle to pulmonary artery conduit associated with improved outcomes? Critical appraisal of Cua et al: Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit (Pediatr Crit Care Med 2006; 7:238-244)

OBJECTIVE

To review the findings and discuss the implications of studies comparing Norwood procedure with either modified Blalock-Taussig shunt (NW-BT) or right ventricle to pulmonary artery conduit (NW-RVPA) in stage I palliation of hypoplastic left heart syndrome (HLHS).

DESIGN

A critical appraisal of "Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit" by Cua et al. (Pediatr Crit Care Med 2006; 7:238-244) with literature review.

FINDINGS

Several retrospective studies using historical controls have reported improved results with NW-RVPA compared with NW-BT for stage I palliation of HLHS. The study by Cua et al. is one of a few recent articles with concurrent series that have found no difference in early postoperative mortality or morbidity, although in comparison with the NW-BT group, the NW-RVPA group had significantly shorter duration of mechanical ventilation, decreased length of intensive care unit stay and hospital stay, and shorter time to sternal closure and to establishment of enteral feeds.

CONCLUSIONS

NW-RVPA has theoretical advantages over NW-BT and is associated with excellent outcome results. However, available data are insufficient to prove benefit in terms of mortality or morbidity. A multicenter randomized trial is currently being conducted, which should provide more conclusive information.

Risk factors for interstage death after stage 1 reconstruction of hypoplastic left heart syndrome and variants

OBJECTIVE

The risk of death during the interstage period remains high after stage 1 reconstruction for single ventricle lesions, despite improved surgical results. The purpose of this study is to identify risk factors for interstage death and to describe the events leading to interstage death.

METHODS

A nested case-control study was conducted of 368 patients who underwent stage 1 reconstruction at a single center between January 1998 and April 2005.

RESULTS

Among the 313 (85%) hospital survivors, there were 33 (10.5%) interstage deaths. Cases more frequently presented with intact or restrictive atrial septum (9 [27%] vs 4 [4%]; P < .001), were older at the time of surgery (5 [2-40] vs 3 [1-42] days; P = .005), had more postoperative arrhythmias (12 [36%] vs 15 [15%]; P = .01), and a higher incidence of airway or respiratory complications (12 [36%] vs 19 [19%]; P = .04). By multivariate analysis, only intact atrial septum (odds ratio 7.6; 95% confidence intervals 1.9-29.6; P = .003) and age at operation greater than 7 days (odds ratio 3.8; 95% confidence intervals 1.3-11.2; P = .017) were predictors of interstage death.

CONCLUSIONS

The presence of intact atrial septum and older age at the time of surgery are associated with a higher risk of interstage death. In addition, postoperative arrhythmia and airway complications are associated with a higher risk of interstage death in univariate analysis. The results of this study provide a focus for interstage monitoring and risk stratification of these high-risk infants, which may improve overall survival.

Design and rationale of a randomized trial comparing the Blalock-Taussig and right ventricle-pulmonary artery shunts in the Norwood procedure

OBJECTIVE

The initial palliative procedure for patients born with hypoplastic left heart syndrome and related single right ventricle anomalies, the Norwood procedure, remains among the highest risk procedures in congenital heart surgery. The classic Norwood procedure provides pulmonary blood flow with a modified Blalock-Taussig shunt. Improved outcomes have been reported in a few small, nonrandomized studies of a modification of the Norwood procedure that uses a right ventricle-pulmonary artery shunt to provide pulmonary blood flow. Other nonrandomized studies have shown no differences between the two techniques.

METHODS

The Pediatric Heart Network designed a randomized clinical trial to compare outcomes for subjects undergoing a Norwood procedure with either the right ventricle-pulmonary artery or modified Blalock-Taussig shunt. Infants with a diagnosis of single, morphologically right ventricle anomaly who are undergoing a Norwood procedure are eligible for inclusion in this study. The primary outcome is death or cardiac transplant 12 months after random assignment. Secondary outcomes include postoperative morbidity after Norwood and stage II palliation procedures, right ventricular function and pulmonary arterial growth at stage II palliation, and neurodevelopmental outcomes at 14 months old. Incidence of adverse events will also be compared between treatment groups.

CONCLUSION

This study will make an important contribution to the care of patients with hypoplastic left heart syndrome and related forms of single, morphologically right ventricle. It also establishes a model with which other operative interventions for patients with congenital cardiovascular malformations can be evaluated in the future.

Outcomes after bidirectional Glenn operation: Blalock-Taussig shunt versus right ventricle-to-pulmonary artery conduit

BACKGROUND

There are distinct physiologic differences between patients with single-ventricle lesions who have undergone the Norwood procedure with a right ventricle-to-pulmonary artery conduit (NW-RVPA) compared with those patients who have undergone the Norwood operation with a Blalock-Taussig shunt (NW-BTS). We evaluated bidirectional Glenn operation outcomes and compared the two groups to assess whether the type of Norwood operation influenced outcomes.

METHODS

A retrospective chart review compared bidirectional Glenn operation outcomes for children undergoing the Norwood operation with NW-RVPA or NW-BTS at Children's Hospital Boston from January 1, 2002, to December 31, 2003.

RESULTS

Of 80 patients undergoing the Norwood operation, 56 (NW-BTS, 27 versus NW-RVPA, 29) returned for the bidirectional Glenn operation at our institution. The NW-RVPA group had a lower median age at presentation for bidirectional Glenn (4.5 months versus 5.8 months; p = 0.01), but had better weight gain (20.6 g/day versus 16.5 g/day; p = 0.03) than the NW-BTS group. No interstage deaths occurred in the NW-RVPA group. There were no differences in morbidity or mortality after the BDG between the two groups.

CONCLUSIONS

There were no differences in morbidity and mortality outcomes after the bidirectional Glenn operation between the NW-RVPA and NW-BTS groups. Despite younger age at presentation, the NW-RVPA patients had better growth rate, which may have contributed to the similar postoperative outcomes.

Does a ventriculotomy have deleterious effects following palliation in the Norwood procedure using a shunt placed from the right ventricle to the pulmonary arteries?

INTRODUCTION

A recent modification to the Norwood procedure involving a shunt placed directly from the right ventricle to the pulmonary arteries may improve postoperative haemodynamics. Concerns remain, however, about the potential problems produced by the required ventriculotomy.

METHODS

We compared 76 patients with hypoplastic left heart syndrome who underwent the Norwood procedure, 35 receiving a modified Blalock-Taussig shunt and the remaining 41 a shunt placed directly from the right ventricle to the pulmonary arteries. We reviewed their subsequent progress through the second stage of palliation. A single observer graded right ventricular function, and the severity of tricuspid regurgitation, based on blinded review of the most recent echocardiograms prior to the second stage of palliation.

RESULTS

At the time of catheterization prior to the second stage, patients with a shunt placed from the right ventricle to the pulmonary arteries, rather than a modified Blalock-Taussig shunt, had higher arterial diastolic blood pressure, at 44 versus 40 millimetres of mercury, p equal to 0.02, lower ventricular end diastolic pressures, at 8 versus 11 millimetres of mercury, p equal to 0.0002, and larger pulmonary arteries as judged using the Nakata index, at 270 versus 188 millimetres squared per metres squared, p equal to 0.009. There was no difference in qualitative ventricular systolic function or tricuspid regurgitation between groups. No differences were found between groups during the hospitalization following the second stage of palliation. A trend towards improved survival to the second stage was seen following the construction of a shunt from the right ventricle to the pulmonary arteries.

CONCLUSIONS

Construction of a shunt from the right ventricle to the pulmonary arteries is associated with lower right ventricular end diastolic pressures, larger pulmonary arterial size, and higher systemic arterial diastolic pressures. No apparent deleterious effects of the right ventriculotomy were observed in terms of qualitative ventricular systolic function or tricuspid regurgitation.

Stage I palliation for hypoplastic left heart syndrome: Norwood versus Sano modification

PURPOSE OF REVIEW

Advancements in surgical technique and perioperative care have significantly improved the survival of infants born with hypoplastic left heart syndrome. A recent modification to the Norwood procedure is being adopted by many centers to improve postoperative hemodynamic stability and survival to stage II palliation. The late effects of this modification, however, are speculated and have not been investigated.

RECENT FINDINGS

Center-specific improved short-term outcomes have been reported in a few small, nonrandomized studies of a new approach to the Norwood procedure, which utilizes a right ventricle to pulmonary artery shunt or Sano modification to provide pulmonary blood flow rather than the standard modified Blalock-Taussig shunt.

SUMMARY

The classic Norwood procedure and Sano modification each have specific advantages and disadvantages in both the short and long term. Data comparing the two techniques are nonrandomized, contradictory, and utilize historical controls. The optimal shunt to improve survival to the second-stage palliation is unknown. A multicenter randomized clinical trial comparing the Sano with the modified Blalock-Taussig shunt in hypoplastic left heart syndrome or variants is currently in progress and should hopefully provide future guidelines for shunt selection based on clinical presentation.

The modified Blalock-Taussig shunt versus the right ventricle-to-pulmonary artery conduit for the Norwood procedure

The initial Norwood procedure remains the highest risk operation for the staged repair of univentricular congenital malformations with associated systemic outflow obstruction. The modified Blalock-Taussig shunt (MBTS) has been implicated as a major cause of not only the operative mortality, but also associated morbidity and interstage attrition. The etiology of these events has often been attributed to the diastolic runoff and "coronary steal" associated with the MBTS, in addition to the delicate balance between systemic and pulmonary blood flow that characterizes all systemic-to-pulmonary artery shunts. Recently, there has been renewed interest in the right ventricle-to-pulmonary artery conduit as a source of pulmonary blood flow for the Norwood procedure as a potential method for minimizing the negative aspects of the MBTS. The current literature is contradictory, retrospective, and predominantly historically controlled. The Trial of Right Ventricular vs Modified Blalock-Taussig Shunt in Infants with Single Ventricle Defect Undergoing Staged Reconstruction, a randomized controlled clinical trial comparing the two techniques, is ongoing and may provide answers to this controversy.

Regional Low-Flow Perfusion Versus Circulatory Arrest in Neonates: One-Year Neurodevelopmental Outcome

BACKGROUND

Regional low-flow perfusion of the brain is a bypass technique commonly used during stage 1 reconstruction in neonates with hypoplastic left heart syndrome and related variants. The neurodevelopmental outcome of these children is unknown.

METHODS

Twenty-nine infants (22 boys, 7 girls) with hypoplastic left heart syndrome or variant requiring single ventricle palliation and aortic arch reconstruction were studied between 1999 and 2004. Mental Developmental Index (MDI) and Psychomotor Developmental Index were assessed using Bayley Scales of Infant Development and correlated with intraoperative and perioperative variables. Results are reported as mean +/- standard deviation.

RESULTS

Average age at stage 1 operation and at bidirectional Glenn was 7 +/- 8 days and 6.0 +/- 2 months, respectively. The MDI was in the low average range (87.7 +/- 13.2). The Psychomotor Developmental Index was in the mildly delayed range (75.2 +/- 14.5). Regional low-flow perfusion was used in 31% (9 of 29 patients), with an average circulatory arrest time of 23.5 +/- 13.4 minutes. Deep hypothermia and circulatory arrest was used as the primary operative strategy in 69% of patients (20 of 29 patients), with an average circulatory arrest time of 44.3 +/- 15.3 minutes (p = 0.003). No differences in MDI or Psychomotor Developmental Index scores were observed between the regional low-flow perfusion and non-regional low-flow perfusion groups (MDI, 88.0 +/- 12.1 versus 87.6 +/- 14.0; p = 0.93, respectively; Psychomotor Developmental Index, 75.5 +/- 15.1 versus 75.0 +/- 14.6; p = 0.93, respectively). Lowest operative temperature (<16 degrees C) and birth order (<2 versus >3) significantly related to MDI (89.6 versus 72.8; p = 0.047).

CONCLUSIONS

At 1 year of age, neurodevelopmental outcomes of patients undergoing stage 1 using regional low-flow perfusion were similar to outcomes observed in children exposed to circulatory arrest. The association of birth order and MDI suggests that early intervention may benefit these patients.

Outcomes after the stage I reconstruction comparing the right ventricular to pulmonary artery conduit with the modified Blalock Taussig shunt

BACKGROUND

Recent reports advocate that a right ventricular to pulmonary artery (RV-PA) conduit improves outcome after the stage I reconstruction.

METHODS

We retrospectively compared the outcomes of all neonates who underwent a stage I reconstruction between January 1, 2002, and October 1, 2004, with use of the RV-PA conduit and modified Blalock-Taussig shunt (mBTS) interspersed over this time period.

RESULTS

In all, 149 infants underwent a stage I reconstruction (95 mBTS, 54 RV-PA) for hypoplastic left heart syndrome (HLHS) or variants. There was a preference for the RV-PA conduit in patients with aortic atresia (mBTS 30% versus RV-PA 67%, p < 0.01). There was no difference in surgical mortality (mBTS 14% versus RV-PA 17%, p = 0.67), time to extubation (mBTS 4.5 +/- 4.8 days versus RV-PA 3.9 +/- 3.5 days, p = 0.47), or length of hospital stay (mBTS 25 +/- 29 days versus RV-PA 21 +/- 23 days, p = 0.52). There was an increased incidence of shunt reinterventions in the patients with the RV-PA conduit (mBTS 17% versus RV-PA 32%, p = 0.04). Patients with RV-PA conduit returned earlier for stage II reconstruction (mBTS 6.5 +/- 2.5 months versus RV-PA 5.6 +/- 1.7 months, p = 0.05). There was no difference in overall mortality (mBTS 32% versus RV-PA 30%, p = 0.45) with a median duration of follow-up of 18 +/- 8 months.

CONCLUSIONS

Comparing shunt strategies (mBTS versus RV-PA) over the same time period, we found no difference in outcome. These data support the need for a larger prospective, randomized trial.

Right Ventricle–to–Pulmonary Artery Conduit Versus Blalock-Taussig Shunt: A Hemodynamic Comparison

BACKGROUND

A comprehensive assessment of 48 hour postoperative hemodynamics in neonates randomized to the right ventricle-to-pulmonary artery (RV-PA) conduit or modified Blalock-Taussig (BT) shunt for stage 1 palliation of hypoplastic left heart syndrome was performed to determine the potential benefits of the modified technique.

METHODS

Randomization to either RV-PA conduit or BT shunt was stratified by surgeon and the presence of aortic atresia. The designated procedure was performed by using hypothermic cardiopulmonary bypass with phenoxybenzamine, continuous cerebral perfusion, pH-stat blood gas management, and continuous postoperative venous oximetry. Differences between treatments were analyzed by time-series generalized least-squares regression, chi2 tests, two-way repeated measures analysis of variance, and the Levene variance ratio test for variability in parameters, as appropriate.

RESULTS

All patients underwent the procedure to which they were randomized. There were no differences in age, weight, deep hypothermic circulatory arrest, or cardiopulmonary bypass times between patients receiving the BT shunt (n = 8) or the RV-PA conduit (n = 9). There was one early and one late death in the RV-PA conduit group, and one interstage death in the BT shunt group. Other than diastolic blood pressure (39 mm Hg in BT shunt versus 46 mm Hg in RV-PA conduit, p < 0.001), there were no differences in the mean values of arterial saturation, venous oximetry, mean arterial blood pressure, pulmonary-to-systemic flow ratio (Qp/Qs), or any other physiologic or inotropic support variable between groups. The variability of physiologic values related to pulmonary blood flow was greater in the RV-PA group (Qp/Qs coefficient of variation, 0.91 versus 2.50, p < 0.001).

CONCLUSIONS

In this randomized prospective study, no hemodynamic benefits of the RV-PA modification for stage 1 palliation of hypoplastic left heart syndrome were found. Pulmonary blood flow was more variable, and the diastolic blood pressure was higher. These findings did not influence indicators of systemic oxygen delivery with our afterload reduction strategy.

Homograft valved right ventricle to pulmonary artery conduit as a modification of the Norwood procedure

BACKGROUND

The use of a right ventricle to pulmonary artery (RV-PA) conduit in the Norwood procedure has been proposed to increase postoperative hemodynamic stability. A valve within the conduit should further decrease RV volume load. We report our clinical experience with this modification.

METHODS AND RESULTS

From February 2002 through August 2005, we performed 88 consecutive Norwood procedures using RV-PA conduits. We used composite valved conduits made from cryopreserved homograft and polytetrafluoroethylene (PTFE) in 66 cases (54 pulmonary, 12 aortic homografts), other valved conduits in 14, and unvalved PTFE in 8 cases. Hospital survival was 88.6% overall and increased to 93.1% after the initial year. Early interventions were required in 18 patients (16 for cyanosis). Prestage II cardiac catheterization was performed at a mean age of 126 days. Mean Qp/Qs was 1, with mean aortic saturation 71%, mean O2 extraction 24%, and mean right ventricular end-diastolic pressure 9 mm Hg. Patient weight, use of an aortic homograft valve in the conduit, stage I palliation within the first year of our experience, and low O2 extraction and high transpulmonary gradient prestage II were risk factors for overall death. Early interventions were more frequent in aortic valve conduits compared with all other conduits.

CONCLUSIONS

The valved RV-PA conduit was associated with low early mortality after the Norwood procedure. The majority of these patients had normal cardiac output and well-maintained RV function. There may be a higher risk for early conduit interventions and death when aortic valve homografts are used in the RV-PA conduit.

Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit

OBJECTIVE

Previous publications using nonconcurrent series of patients indicate improved survival for patients with hypoplastic left heart syndrome (HLHS) undergoing stage I palliation with a right ventricle to pulmonary artery conduit (NW-RVPA) vs. a modified Blalock-Taussig shunt (NW-BT). We compared postoperative outcomes in a concurrent series of patients with HLHS undergoing an NW-BT procedure vs. NW-RVPA procedure.

DESIGN

Perioperative data from 66 consecutive patients who underwent NW-BT (n = 37) or NW-RVPA (n = 29) procedures were retrospectively analyzed.

SETTING

Cardiac intensive care unit in a tertiary pediatric hospital.

PATIENTS

Charts were reviewed for all patients with the diagnosis of HLHS undergoing the NW-BT or NW-RVPA procedure between January 2002 and December 2003.

RESULTS

Cardiopulmonary bypass time was longer in the NW-BT group than in the NW-RVPA group (152.5 +/- 52.0 vs. 134.5 +/- 36.1 mins; p = .04). Postoperative diastolic pressures were higher and the Pao2 to Fio2 ratio profiles were lower for the NW-RVPA group over the first 72 hrs. Time to sternal closure (2 [1-6] vs. 4 [2-41] days; p = .01), duration of mechanical ventilation (113 [49-386] vs. 136 [84-764] hrs; p = .01), time to establish enteral feeds (4 [2-8] vs. 5 [3-22] days; p = .01), length of intensive care unit stay (11 [7-55] vs. 15 [8-90] days; p = .04), and length of hospital stay (16 [11-67] vs. 27 [12-126] days; p = .01) were shorter in the NW-RVPA group. Postoperative mortality was not significantly different between the NW-RVPA group (7%) and NW-BT group (11%).

CONCLUSION

At an experienced institution with low stage I palliation mortality for HLHS, there were no differences in early morbidity and mortality between the NW-RVPA and NW-BT procedures. The primary advantage of the NW-RVPA procedure may be faster recovery following surgery and earlier discharge from the hospital.