Right Ventricle-to-pulmonary Artery Shunt Research Articles

Surgical Modulation of Pulmonary Artery Shear Stress: A Patient-Specific CFD Analysis of the Norwood Procedure.

This study created 3D CFD models of the Norwood procedure for hypoplastic left heart syndrome (HLHS) using standard angiography and echocardiogram data to investigate the impact of shunt characteristics on pulmonary artery (PA) hemodynamics. Leveraging routine clinical data offers advantages such as availability and cost-effectiveness without subjecting patients to additional invasive procedures. Patient-specific geometries of the intrathoracic arteries of two Norwood patients were generated from biplane cineangiograms. "Virtual surgery" was then performed to simulate the hemodynamics of alternative PA shunt configurations, including shunt type (modified Blalock-Thomas-Taussig shunt (mBTTS) vs. right ventricle-to-pulmonary artery shunt (RVPAS)), shunt diameter, and pulmonary artery anastomosis angle. Left-right pulmonary flow differential, Qp/Qs, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) were evaluated. There was strong agreement between clinically measured data and CFD model output throughout the patient-specific models. Geometries with a RVPAS tended toward more balanced left-right pulmonary flow, lower Qp/Qs, and greater TAWSS and OSI than models with a mBTTS. For both shunt types, larger shunts resulted in a higher Qp/Qs and higher TAWSS, with minimal effect on OSI. Low TAWSS areas correlated with regions of low flow and changing the PA-shunt anastomosis angle to face toward low TAWSS regions increased TAWSS. Excellent correlation between clinically measured and CFD model data shows that 3D CFD models of HLHS Norwood can be developed using standard angiography and echocardiographic data. The CFD analysis also revealed consistent changes in PA TAWSS, flow differential, and OSI as a function of shunt characteristics.

Longitudinal Follow-Up of Children With HLHS and Association Between Norwood Shunt Type and Long-Term Outcomes: The SVR III Study.

In the SVR trial (Single Ventricle Reconstruction), newborns with hypoplastic left heart syndrome were randomly assigned to receive a modified Blalock-Taussig-Thomas shunt (mBTTS) or a right ventricle-to-pulmonary artery shunt (RVPAS) at Norwood operation. Transplant-free survival was superior in the RVPAS group at 1 year, but no longer differed by treatment group at 6 years; both treatment groups had accumulated important morbidities. In the third follow-up of this cohort (SVRIII [Long-Term Outcomes of Children With Hypoplastic Left Heart Syndrome and the Impact of Norwood Shunt Type]), we measured longitudinal outcomes and their risk factors through 12 years of age. Annual medical history was collected through record review and telephone interviews. Cardiac magnetic resonance imaging (CMR), echocardiogram, and cycle ergometry cardiopulmonary exercise tests were performed at 10 through 14 years of age among participants with Fontan physiology. Differences in transplant-free survival and complication rates (eg, arrhythmias or protein-losing enteropathy) were identified through 12 years of age. The primary study outcome was right ventricular ejection fraction (RVEF) by CMR, and primary analyses were according to shunt type received. Multivariable linear and Cox regression models were created for RVEF by CMR and post-Fontan transplant-free survival. Among 549 participants enrolled in SVR, 237 of 313 (76%; 60.7% male) transplant-free survivors (mBTTS, 105 of 147; RVPAS, 129 of 161; both, 3 of 5) participated in SVRIII. RVEF by CMR was similar in the shunt groups (RVPAS, 51±9.6 [n=90], and mBTTS, 52±7.4 [n=75]; P=0.43). The RVPAS and mBTTS groups did not differ in transplant-free survival by 12 years of age (163 of 277 [59%] versus 144 of 267 [54%], respectively; P=0.11), percentage predicted peak Vo2 for age and sex (74±18% [n=91] versus 72±18% [n=84]; P=0.71), or percentage predicted work rate for size and sex (65±20% versus 64±19%; P=0.65). The RVPAS versus mBTTS group had a higher cumulative incidence of protein-losing enteropathy (5% versus 2%; P=0.04) and of catheter interventions (14 versus 10 per 100 patient-years; P=0.01), but had similar rates of other complications. By 12 years after the Norwood operation, shunt type has minimal association with RVEF, peak Vo2, complication rates, and transplant-free survival. RVEF is preserved among the subgroup of survivors who underwent CMR assessment. Low transplant-free survival, poor exercise performance, and accruing morbidities highlight the need for innovative strategies to improve long-term outcomes in patients with hypoplastic left heart syndrome. URL: https://www. gov; Unique identifier: NCT0245531.

Abstract 10502: Impact of Norwood Shunt Type on Cardiac Function and Clinical Outcomes in Survivors to Early Adolescence with Hypoplastic Left Heart Syndrome and Other Single Right Ventricular Anomalies: A Report from the Single Ventricle Reconstruction (SVR) III Study

Introduction: The SVR Trial demonstrated that the right ventricle-to-pulmonary artery shunt (RVPAS) vs. modified Blalock-Taussig-Thomas shunt (MBTTS) at Norwood operation was associated with better early survival for children with hypoplastic left heart syndrome (HLHS). However, it remains unclear if shunt type is associated with cardiac function, morbidities or survival in older children. Methods: SVR Trial survivors were followed annually. Cardiac MRI and cycle ergometry were performed at 10-12 years (y) of age for SVR III participants. Outcomes were compared by shunt type received (presented) and intention to treat, using linear, Poisson and Cox proportional hazards regression. Results: Among 549 children in the SVR Trial, 237 of 313 eligible transplant-free survivors returned for follow-up at median (IQR) 10.9 (10.4-11.5) y. Transplant-free survival at 12 y was 59% for the RVPAS vs 54% for the MBTTS, with no difference in survival conditional on Stage II survival. Ejection fraction (EF) was measured by MRI in 168 participants, with no difference between groups (RVPAS median 53 [IQR 46-58] and MBTTS 52 [IQR 48-56], p=.38). In multivariable modeling, the percent variance in EF explained by pre-Norwood and Norwood variables including shunt type was low (R 2 < .2). Cycle ergometry was performed in 181 participants with no difference by shunt type in peak VO 2 (ml/kg/minute) (RVPAS 30 [IQR 25-36] vs. MBTTS 29 [IQR 24-33], p=.26) or in peak work rate (RVPAS 67±24 watts vs MBTTS 66±20 watts, p=.61). By age 12 y, the RVPAS group had a higher rate of PLE (5% vs. 2%, p =.04) and catheter interventions (14 vs 10 per 100 pt-y; p=0.01). Otherwise the cumulative incidence of events and complications were similar for shunt groups with stroke in 7%, seizure 14%, plastic bronchitis 1%, atrial tachyarrhythmias 7% and ventricular tachyarrhythmias 3%. Conclusion: By 12 y after Norwood, shunt type has minimal effect on post-Stage II transplant-free survival, cardiac function or exercise performance. EF is preserved in most transplant-free survivors. However, low and declining transplant-free survival, poor exercise performance, and accruing morbidities highlight the critical need for innovative strategies to improve long-term outcomes in patients with HLHS.

Postoperative Renal Failure, Shunt Type, and Mortality After Norwood Palliation

BackgroundThe Single Ventricle Reconstruction Trial demonstrated increased risk of death or heart transplant 1 year after Norwood among subjects randomly assigned to modified Blalock-Taussig shunts compared with right ventricle to pulmonary artery (RV-PA) shunts. We used the Single Ventricle Reconstruction Trial public use database to evaluate incidence and risk factors for postoperative renal failure and relationships between renal failure, shunt type, and outcomes after Norwood. MethodsPostoperative renal failure was defined a priori as a threefold rise in creatinine from baseline, or dialysis use, within 7 days of Norwood. We used multivariate logistic regression to evaluate risk factors for postoperative renal failure and Cox hazard regression to determine the association between postoperative renal failure and 1 year after Norwood mortality. ResultsOverall, postoperative renal failure occurred in 8.4% (46 of 544) patients with risk factors including receipt of a modified Blalock-Taussig shunt (adjusted odds ratio [aOR] 3.3, P = .02), low center volume (aOR 2.7, P = .005), two or more preoperative complications (aOR 4.0, P < .001), low birth weight (aOR 3.2, P = .002), postoperative heart block (aOR 8.5, P = .001), and delayed sternal closure (aOR 5.3, P = .026). Renal failure was an independent risk factor for 1-year mortality (aHR 1.9, P = .019). Assessing interaction by shunt type, mortality risk associated with renal failure was greatest in the RV-PA shunt group (aHR 3.3 vs RV-PA shunt without renal failure, P = .001), but was also increased in the modified Blalock-Taussig shunt group (aHR 1.9, P = .03). ConclusionsPostoperative renal failure is common after Norwood and is independently associated with mortality. Although renal failure is more common after modified Blalock-Taussig shunt, the highest mortality risk with renal failure occurs after RV-PA shunt.

Abstract 13342: Increasing Use of the Right Ventricle to Pulmonary Artery Shunt for Stage 1 Palliation: A Report From the National Pediatric Cardiology Quality Improvement Collaborative

Introduction: Stage 1 palliation (S1P) of single ventricle heart defects with aortic hypoplasia consists of either the Norwood operation with a modified Blalock-Taussig shunt (MBTS) or a right ventricle-to-pulmonary artery shunt (RVPAS), or a hybrid procedure. Changes in national trends over time and factors influencing surgical approach remain unclear. Hypothesis: There has been an increase in national use of the RVPAS for S1P. Methods: Data from the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) phase 1 (6/2008-8/2016) and phase 2 (8/2016-9/2019) databases were used. S1P type was evaluated by year of operation. Factors influencing the choice of MBTS versus RVPAS, as well as length of stay after S1P and mortality prior to Stage 2 palliation (S2P) between shunt types, were evaluated. Sites were stratified by the number of patients in the database per year as small (&lt;5), medium (&lt;10) and large (≥10) centers. Results: The combined database included 3335 eligible patients; 1,028 (30.8%) with MBTS, 1,989 (59.7%) with RVPAS, and 318 (9.5%) with hybrid procedure. Overall, of 62 centers, 14.6% of S1P were at small centers (n=26), 40.6% at medium centers (n=24), and 44.7% at large centers (n=12). There was an increase in RVPAS use over time (p=0.02). In multivariable analysis, increasing hospital volume (OR 1.2 [95% CI 1.1-1.4], p=0.003) and absence of other organ system anomalies (OR 1.5 [95% CI 1.0-2.2], p=0.049) were associated with MBTS use over RVPAS. Median length of stay after S1P with MBTS was longer than with RVPAS (31 [95% CI 20-49] vs 29 [95% CI 19-47] days, p=0.054) and mortality was higher prior to S2P (12.3% vs 9.6%, p=0.03). Conclusions: Use of RVPAS with S1P has increased over time with a decrease in MBTS use and unchanged hybrid frequency. MBTS is used more commonly in centers with higher volume and in patients without other anomalies but is associated with longer post-op hospitalization and lower transplant-free survival to stage 2 palliation.

Abstract 15117: The Catheter Uncertainty Principle: Does the Presence of a Catheter Alter Hemodynamics?

Introduction: Catheters are an essential component of measuring invasive hemodynamic quantities. However, by the very nature of a catheter's presence, it acts to disturb the normal flow field, potentially altering measured pressures and derived quantities, such as FFR. Computational fluid dynamic simulations are performed to explore how vessel lumenal area and catheter size effect pressures. Methods: Patient-specific anatomical reconstructions are coupled with HARVEY, a massively parallel lattice-Boltzmann fluid solver, to calculate 3D blood flow around simulated catheters. We explore the effects of catheter size in vessels ranging from 5 mm in diameter, a right ventricle to pulmonary artery shunt (RVPAS) in a patient with HLHS, and smaller, in coronary arteries. Pressures sampled at the location corresponding to the distal end of the catheter are compared and FFR is calculated for the coronary models. Results: Figure 1A illustrates the calculated pressure waveforms for simulated catheter sizes in a RVPAS. In this case, the catheter does not significantly alter the pressure field unless unrealistically large catheters, such as a 13 Fr, are used. For adult coronary arteries (Figure 1B), reasonable catheter sizes result in appreciable decreases in sampled pressures and, consequently, in calculated FFR (Figure 1C). Conclusion: The presence of a sufficiently large catheter (&gt;50% of the vessel lumenal area) causes a noticeable decrease in the pressures at the tip of the catheter. While unlikely to occur in larger vessels, this can occur during left heart catheterizations of diseased coronary arteries. This causes an artificial decrease in FFR, which can potentially alter clinical decision making. While catheters are the gold standard for pressure measurements, an improved understanding of the inherent sensitivity of their measurements to unobstructed vessel lumenal area is important for interpreting the results of catheter-based diagnostic procedures.

Cobra-Head Cuffed Vascular Graft as Right Ventricle-to-Pulmonary Artery Shunt in Norwood Procedure

Right ventricle-to-pulmonary artery (RV-PA) shunt as a part of the Norwood procedure underwent many modifications. We present our experience with a commercially available polytetrafluoroethylene vascular graft with cobra-head cuff as an RV-PA shunt. A consecutive series of 52 children with hypoplastic left heart syndrome (median age 8 [range, 2-68] days, median weight 3200 [range, 2060-4400] g) underwent the Norwood procedure with a cobra-head cuffed RV-PA shunt (6 mm). The cuffed end was used for the central PA reconstruction. A retrospective analysis of clinical results, PAs development, and shunt-related complications, interventions, and technique of Glenn operation was performed. The study endpoint was Glenn operation with shunt removal or interstage death. The hospital and late interstage mortality was 3.8% (n= 2 of 52) and 4% (n= 2 of 50), respectively, and was not shunt-related. During mean follow of 3.7 ± 2.5 years, 48 (92.3%) children underwent Glenn operation at a median age of 6 (range, 2.6-9.1) months. Angiography before the second stage revealed satisfactory branch PAsdevelopment (maximum and minimum McGoon ratio of 1.95 ± 0.36 and 1.38 ± 0.38, respectively). The meanmaximal diameter of the left PA was smaller than that of the right PA (7.13 ± 2.1 mm vs 8.42 ± 2.2 mm; P=.017), without differences in mean minimal diameter. Two infants required stent implantation in proximal shunt end and 1 required urgent Glenn operation becausedistal shunt thrombosis. During Glenn operation, 11 (22.9%) children required patch reconstruction of central PAs. The cobra-head cuffed graft allowed easy and reproducible reconstruction of the central PA during the Norwood procedure. Using this technique, the development of PAs is satisfactory, the rate of shunt-related complications and interventions is low, and the second stage can be performed without patch material.

Geometry of the pulmonary arteries before the Fontan operation: can we influence it during the Norwood procedure?

The right ventricle-to-pulmonary artery (RV-PA) shunt provides stable haemodynamics after the Norwood procedure but can influence development of the central pulmonary arteries (PAs). The goal of this study was to analyse the geometry of the central PAs in children with hypoplastic left heart syndrome before the Fontan operation with respect to the RV-PA shunt site and the type of the second-stage operation. A total of 161 children with hypoplastic left heart syndrome, median age 2.7 (range 1.3-9.8) years and median weight 12.7 (range 7.6-26.1) kg, underwent the Fontan operation after having had the Norwood procedure with an RV-PA shunt. The patients were divided into 2 groups: left-sided RV-PA (L-RV-PA) (n = 129) with the shunt on the left and right-sided RV-PA (n = 32) with the shunt on the right side of the neoaorta. Angiographic data obtained before the Fontan and all cardiac catheterization interventions were analysed retrospectively. Between the second and third stages, as well as directly before the Fontan operation, the L-RV-PA group required more PA catheter interventions (P = 0.001 and P = 0.03). In this group, the minimal left PA diameter was smaller than that in the R-RV-PA group (P = 0.021). Leaving the shunt open until the Fontan operation increased the rate of PA interventions in the L-RV-PA group (P = 0.001), but there is no evidence of the impact on the development of the left PAs (P = 0.075). There is also no evidence that the type of the second-stage procedure influences the intervention rate before the Fontan procedure (P = 0.14). Children who have the L-RV-PA shunt require more PA catheter interventions. The right-sided RV-PA shunt and the subsequent Glenn anastomosis in the place of the shunt are associated with distortion-free and more symmetrical development of the central PAs.

2205 Thrombotic complications in single ventricle reconstructions for single ventricle physiology congenital heart disease

2205 Thrombotic complications in single ventricle reconstructions for single ventricle physiology congenital heart disease

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

BackgroundStage 1 palliation of hypoplastic left heart syndrome (HLHS) involves the Norwood procedure combined with a modified Blalock–Taussig shunt (mBTS) or right ventricle to pulmonary artery shunt (RVPAS). Short-term survival has been described previously, whereas longer-term outcomes remain a subject of debate. This meta-analysis aimed to describe the short and long-term survival outcomes of these two shunts, and explore factors that might influence survival. MethodsMedline, Cochrane Libraries and EMBASE were systematically searched, and 32 studies were included for statistical synthesis, comprising 1348 mBTS and 1258 RVPAS patients. ResultsWhile early in-hospital survival was superior in the RVPAS group (RR=1.5, p<0.05, 95% CI: 1.21–1.85), this difference was lost from 2years post-stage 1 palliation (RR=0.91, p>0.05, 95% CI: 0.79–1.04), and maintained unchanged up to 6years. This shift in survival was also reflected in inter-stage survival, with superior RVPAS outcomes between stage 1 and 2 (RR=1.62, p<0.05, 95% CI: 1.39–1.88), and equivalent outcomes between stage 2 and 3. Potential contributors to this included a significantly higher rate of pulmonary artery stenosis in the RVPAS group and an increased requirement for shunt re-intervention in this group prior to stage 2. ConclusionsDespite early advantages, RVPAS and mBTS for palliation of hypoplastic left heart syndrome produced comparable long-term survival. The RVPAS patients experienced more pulmonary artery stenosis and requirement for shunt re-intervention. The impact of shunt type on quality and survival with a Fontan is yet to be assessed.

Pulmonary Vein Doppler Patterns in Infants with Single Right Ventricle Anomalies After Initial Staged Palliations.

The aim of this study was to describe serial changes in echocardiographic Doppler pulmonary vein flow (PVF) patterns in infants with single right ventricle (RV) anomalies enrolled in the Single Ventricle Reconstruction trial. Measurement of PVF peak systolic (S) and diastolic (D) velocities, velocity time integrals (VTI), S/D peak velocity and VTI ratios, and frequency of atrial reversal (Ar) waves were made at three postoperative time points in 261 infants: early post-Norwood, pre-stage II surgery, and 14months. Indices were compared over time, between initial shunt type [modified Blalock-Taussig shunt (MBTS) and right ventricle-to-pulmonary artery shunt (RVPAS)] and in relation to clinical outcomes. S velocities and VTI increased over time while D wave was stable, resulting in increasing S/D peak velocity and VTI ratios, with a median post-Norwood S/D VTI ratio of 1.14 versus 1.38 at pre-stage II and 1.89 at 14months (P<0.0001 between intervals). MBTS subjects had significantly higher S/D peak velocity and VTI ratios compared to RVPAS at the post-Norwood and pre-stage II time points (P<0.0001) but not by 14months. PVF patterns did not correlate with survival or hospitalization course at 1year. PVF patterns after Norwood palliation differ from normal infants by having a dominant systolic pattern throughout infancy. PVF differences based upon shunt type resolve by 14months and did not correlate with clinical outcomes. This study describes normative values and variations in PVF for infants with a single RV from shunt-dependent pulmonary blood flow to cavopulmonary blood flow.

Right Ventricle-to-Pulmonary Artery Shunt in Pulmonary Atresia with a Ventricular Septal Defect: A Word of Caution.

The management of pulmonary atresia with a ventricular septal defect (PA/VSD) depends on the anatomy of the pulmonary artery or on the surgical strategy used at individual institutions. In our institution, we adopted a right ventricle-to-pulmonary artery (RV-PA) shunt in 2011 as a palliative procedure for PA/VSD to overcome the disadvantages of a Blalock-Taussig shunt. We evaluated the results of the RV-PA shunt as initial palliative surgery for PA/VSD. Thirteen patients with ductus-dependent PA/VSD from August 2011 to August 2015 were enrolled. The mean age at surgery was 17.9 ± 15.3 (range 5-60) days, and the mean body weight was 2.9 ± 0.6 (range 2.2-4.0) kg. A Gore-Tex tube graft was used in all patients. We retrospectively observed intra- and postoperative complications, early and late mortality, and palliation duration to definitive repair. Left pulmonary artery angioplasty was performed as a concomitant procedure in three patients. There were no early hospital mortalities, although two inter-stage deaths occurred 34 and 47days postoperatively: one patient died of aspiration and the other of right ventricular outflow tract (RVOT) pseudoaneurysm rupture. Two patients (15.4%) required the extracorporeal membrane oxygenation support postoperatively: one because of failure to wean from a bypass caused by persistent hypoxemia and the other because of sudden massive bleeding from the RVOT suture line in the intensive care unit 2 days postoperatively. These two patients underwent second-stage definitive repair successfully. Five patients (41.7%) required catheter intervention, for juxtaductal left pulmonary artery stenosis in three patients, right pulmonary artery stenosis in one, and shunt inflow stenosis in one. Two patients (15.4%) required re-operation because of shunt inflow stenosis and RVOT pseudoaneurysm, respectively. All patients who survived the RV-PA shunt underwent total correction at a mean interval of 13.1 months. A RV-PA shunt is an option for the initial palliation of ductus-dependent PA/VSD. Major complications can occur, including RVOT pseudoaneurysm, shunt inflow stenosis, persistent hypoxemia during the immediate postoperative period, and dehiscence of the shunt anastomosis site. Caution should be taken when performing the RV-PA shunt for palliation of PA/VSD.

Abstract 14163: The Single Ventricle Reconstruction (SVR) Trial at 6 Years: Transplant-Free Survival, Catheter Interventions, and Morbidity

Background: In the SVR trial, 1-year (y) transplant (tx)-free survival was better for the Norwood procedure with right ventricle-to-pulmonary artery shunt (RVPAS) vs modified Blalock-Taussig shunt (MBTS). At 6 y, we compared tx-free survival, unplanned interventions, morbidities, New York Heart Association (NYHA) Class, and RV ejection fraction (RVEF) by assigned shunt. Methods and Results: The SVR trial treated 549 pts. Vital status and medical history were ascertained annually. Tx-free survival in the RVPAS (63.5%) vs MBTS (58.7%) groups did not differ (Figure; log-rank P=.13). Similarly, neither mortality nor tx alone differed by shunt type. By 6 y, RVPAS pts had a higher incidence of any catheter intervention (.38 vs .23/pt-yr, P&lt;.001), balloon angioplasty (P=.014), stent (P=.009), and coiling (P&lt;.001). The % of pts with morbidities by 6 y were similar in the groups, with overall rates: pacemaker 3%, thrombosis 16%, stroke 7%, seizures 13%, protein losing enteropathy 3%, plastic bronchitis 0.5%, and 6-y NYHA Class I 71%, II 21%, III 3%, and IV 5%. Among pre-specified subgroups, worse tx-free survival was associated with low birth weight (&lt;2500 g); worse pre-Norwood tricuspid regurgitation (≥2.5 mm jet width); lower surgeon Norwood volume; preterm birth (&lt;37 wks); and combined aortic atresia and pre-term birth (all P&lt;.01). Subgroup x shunt interaction was significant only for surgeon volume levels (P&lt;.05); in the highest volume group (n &gt;15/y), the MBTS was beneficial (P&lt;.04), and in 3 lower volume groups, the RVPAS was qualitatively better. In 6-y echoes read to date, RVEF was similar in the RVPAS vs MBTS groups (46±7, n=55 vs 46±6%, n=48; P=.9). Conclusions: By 6 y, tx-free survival was an absolute 4.8% higher for pts assigned to the RVPAS vs MBTS group, but the difference no longer reached statistical significance, and they needed more catheter interventions. Rates of death, tx, and morbidities; distribution of NYHA Class; and RVEF were each similar in the shunt groups.

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

BackgroundIn the Single Ventricle Reconstruction trial, infants with hypoplastic left heart syndrome (HLHS) who received a right-ventricle-to-pulmonary-artery shunt (RVPAS) versus a modified Blalock-Taussig shunt (MBTS) had lower early postoperative mortality, but more complications at 14 months. We explored the effect of shunt type and other patient, medical, and surgical factors on postoperative length of stay (LOS) after the Fontan operation. MethodsFontan postoperative course was ascertained from medical record review. Cox proportional hazards modeling was used to identify factors associated with LOS. ResultsOf 327 subjects who underwent Fontan, 323 were analyzed (1 death, 1 biventricular repair, 2 with missing data). Median age and weight at Fontan were 2.8 years (interquartile range [IQR]: 2.3, 3.4) and 12.7 kg (IQR: 11.4, 14.1), respectively. Fontan type was extracardiac in 55% and lateral tunnel in 45%; 87% were fenestrated. The RVPAS and MBTS subjects had similar LOS (median 11 days [IQR: 9, 18] vs 10 days [IQR: 9, 13]; P = .23). Independent risk factors for longer LOS were treatment center (P < .01), LOS at stage II (hazard ratio [HR] 1.02 for each additional day; P < .01), and pre-Fontan complications (HR 1.03 for each additional complication; P = .04). Use of deep hypothermic circulatory arrest at Fontan (HR 0.64; P = .02) was independently associated with shorter LOS. When center was excluded from the model, pre-Fontan complications and use of circulatory arrest were no longer significant; instead, older age at stage II (HR 1.08 for each additional month; P = .01) predicted longer LOS. In 254 subjects who had a pre-Fontan echocardiogram, at least moderate tricuspid regurgitation was independently associated with longer LOS, both with center (HR 1.72; P < .01) and without center in the model (HR 1.49; P = .02). ConclusionsIn this multicenter prospective cohort of subjects with HLHS, Norwood shunt type was not associated with Fontan LOS. Rather, global measures of earlier medical complexity indicate greater likelihood of longer LOS after the Fontan operation.

Impact of Initial Shunt Type on Cardiac Size and Function in Children With Single Right Ventricle Anomalies Before the Fontan Procedure: The Single Ventricle Reconstruction Extension Trial

BackgroundIn children with single right ventricular (RV) anomalies, changes in RV size and function may be influenced by shunt type chosen at the time of the Norwood procedure. ObjectivesThe study sought to identify shunt-related differences in echocardiographic findings at 14 months and ≤6 months pre-Fontan in survivors of the Norwood procedure. MethodsWe compared 2-dimensional and Doppler echocardiographic indices of RV size and function, neo-aortic and tricuspid valve annulus dimensions and function, and aortic size and patency at 14.1 ± 1.2 months and 33.6 ± 9.6 months in subjects randomized to a Norwood procedure using either the modified Blalock-Taussig shunt (MBTS) or right ventricle to pulmonary artery shunt (RVPAS). ResultsAcceptable echocardiograms were available at both time points in 240 subjects (114 MBTS, 126 RVPAS). At 14 months, all indices were similar between shunt groups. From the 14-month to pre-Fontan echocardiogram, the MBTS group had stable indexed RV volumes and ejection fraction, while the RVPAS group had increased RV end-systolic volume (p = 0.004) and decreased right ventricular ejection fraction (RVEF) (p = 0.004). From 14 months to pre-Fontan, the treatment groups were similar with respect to decline in indexed neo-aortic valve area, >mild neo-aortic valve regurgitation (<5% at each time), indexed tricuspid valve area, and ≥moderate tricuspid valve regurgitation (<20% at each time). ConclusionsInitial Norwood shunt type influences pre-Fontan RV remodeling during the second and third years of life in survivors with single RV anomalies, with greater RVEF deterioration after RVPAS. Encouragingly, other indices of RV function remain stable before Fontan regardless of shunt type. (Comparison of Two Types of Shunts in Infants with Single Ventricle Defect Undergoing Staged Reconstruction—Pediatric Heart Network; NCT00115934)

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

In Search of the Ideal Pulmonary Blood Source for the Norwood Procedure: A Meta-Analysis and Systematic Review

A clear consensus regarding the optimal source of pulmonary blood flow in patients with hypoplastic left heart syndrome undergoing the Norwood procedure is lacking. A literature search was undertaken to identify relevant articles from 2005 to 2012 using "Norwood, stage 1 palliation," "Modified Blalock Taussig shunt (MBTS)," "right ventricle-to-pulmonary artery shunt (RV-PAS)" alone or in combination. Three end points were selected: early/stage 1 mortality, interstage mortality, and interstage total/shunt intervention. A total of 20 articles, including 19 observational studies and 1 randomized trial (MBTS, n=1,343; RV-PAS, n=1,028), met the inclusion criteria. Mortality after stage 1 was 22% in the MBTS cohort and 16% in RV-PAS cohort. A pooled analysis showed no difference in early mortality between the two groups (risk ratio [RR], 1.20; 95% confidence interval [CI], 0.99 to 1.45; p=0.07). On pooling data from contemporary series (similar era) of 8 studies (MBTS, n=709; RV-PAS, n=631), to minimize variability in surgical and postoperative management practices, early mortality in both cohorts was comparable (RR, 1.14; 95% CI, 0.89 to 1.45; p=0.29). Interstage mortality was 13.8% and 4.6% in the MBTS and RV-PAS cohorts, respectively, and was significantly lower for RV-PAS (RR, 2.85; 95% CI, 1.65 to 4.89; p<0.00002). However, patients with MBTS had fewer shunt interventions (RR, 0.55; 95% CI, 0.44 to 0.68; p<0.001; I2=00%). Our pooled analysis demonstrated no survival benefit for the MBTS or RV-PAS in patients undergoing the Norwood procedure. There appears to be an advantage with the RV-PAS with regard to interstage mortality at the cost of an increased rate of shunt intervention.

Transplantation-Free Survival and Interventions at 3 Years in the Single Ventricle Reconstruction Trial

In the Single Ventricle Reconstruction (SVR) trial, 1-year transplantation-free survival was better for the Norwood procedure with right ventricle-to-pulmonary artery shunt (RVPAS) compared with a modified Blalock-Taussig shunt (MBTS). At 3 years, we compared transplantation-free survival, echocardiographic right ventricular ejection fraction, and unplanned interventions in the treatment groups. Vital status and medical history were ascertained from annual medical records, death indexes, and phone interviews. The cohort included 549 patients randomized and treated in the SVR trial. Transplantation-free survival for the RVPAS versus MBTS groups did not differ at 3 years (67% versus 61%; P=0.15) or with all available follow-up of 4.8±1.1 years (log-rank P=0.14). Pre-Fontan right ventricular ejection fraction was lower in the RVPAS group than in the MBTS group (41.7±5.1% versus 44.7±6.0%; P=0.007), and right ventricular ejection fraction deteriorated in RVPAS (P=0.004) but not MBTS (P=0.40) subjects (pre-Fontan minus 14-month mean, -3.25±8.24% versus 0.99±8.80%; P=0.009). The RVPAS versus MBTS treatment effect had nonproportional hazards (P=0.004); the hazard ratio favored the RVPAS before 5 months (hazard ratio=0.63; 95% confidence interval, 0.45-0.88) but the MBTS beyond 1 year (hazard ratio=2.22; 95% confidence interval, 1.07-4.62). By 3 years, RVPAS subjects had a higher incidence of catheter interventions (P<0.001) with an increasing HR over time (P=0.005): <5 months, 1.14 (95% confidence interval, 0.81-1.60); from 5 months to 1 year, 1.94 (95% confidence interval, 1.02-3.69); and >1 year, 2.48 (95% confidence interval, 1.28-4.80). By 3 years, the Norwood procedure with RVPAS compared with MBTS was no longer associated with superior transplantation-free survival. Moreover, RVPAS subjects had slightly worse right ventricular ejection fraction and underwent more catheter interventions with increasing hazard ratio over time. http://www.clinicaltrials.gov. Unique identifier: NCT00115934.

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

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. 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. 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). 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.

Doppler Flow Patterns in the Right Ventricle–to–Pulmonary Artery Shunt and Neo-Aorta in Infants with Single Right Ventricle Anomalies: Impact on Outcome after Initial Staged Palliations

A Pediatric Heart Network trial compared outcomes in infants with single right ventricle anomalies undergoing Norwood procedures randomized to modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS). Doppler patterns in the neo-aorta and RVPAS may characterize physiologic changes after staged palliations that affect outcomes and right ventricular (RV) function. Neo-aortic cardiac index (CI), retrograde fraction (RF) in the descending aorta and RVPAS conduit, RVPAS/neo-aortic systolic ejection time ratio, and systolic/diastolic (S/D) ratio were measured early after Norwood, before stage II palliation, and at 14 months. These parameters were compared with transplantation-free survival, length of hospital stay, and RV functional indices. In 529 subjects (mean follow-up period, 3.0 ± 2.1 years), neo-aortic CI and descending aortic RF were significantly higher in the MBTS cohort after Norwood. The RVPAS RF averaged <25% at both interstage intervals. Higher pre-stage II descending aortic RF was correlated with lower RV ejection fraction (R= -0.24; P=.032) at 14 months for the MBTS cohort. Higher post-Norwood CI (5.6 vs 4.4 L/min/m(2), P= .04) and lower S/D ratio (1.40 vs 1.68, P= .01) were correlated with better interstage transplantation-free survival for the RVPAS cohort. No other Doppler flow patterns were correlated with outcomes. After the Norwood procedure, infants tolerated significant descending aortic RF (MBTS) and conduit RF (RVPAS), with little correlation with clinical outcomes or RV function. Neo-aortic CI, ejection time, and S/D ratios also had limited correlations with outcomes or RV function, but higher post-Norwood neo-aortic CI and lower S/D ratio were correlated with better interstage survival in those with RVPAS.