Right Ventricle-to-pulmonary Artery Conduit Research Articles

Aspirin Responsiveness in a Cohort of Pediatric Patients with Right Ventricle to Pulmonary Artery Conduits and Transcatheter Valve Replacement Systems.

The aim of this study was to determine the rate of aspirin responsiveness in a cohort of pediatric patients with in situ xenograft valved right ventricle to pulmonary artery (RV-PA) conduits and/or transcatheter valve replacements (TVR). Aspirin is routinely prescribed to these patients. Optimizing anti-platelet therapy could promote valve longevity and reduce the risk of infective endocarditis in this at-risk group. This was a prospective, observational study. Patients were recruited from both ward and outpatient settings. Patients were eligible if under 18 years and taking aspirin. Non-response to aspirin was defined as >20% platelet aggregation using light transmission platelet aggregometry (LTA) and <50% platelet inhibition by thromboelastography with platelet mapping (TEGPM). Participants were invited to provide a confirmatory sample in cases of aspirin resistance and dose adjustments were made. Thirty patients participated. Median age was 9 years (2 months to 18 years). The majority (93%) had complex right ventricular outflow tract pathology. 13 (43%) had an RV-PA conduit and 24 (80%) had a TVR, with valve situated in conduit in 7 (23%) cases. Rate of aspirin non-response on initial testing was 23% (n=7/30) with median LTA 74.55% (60-76%) and TEG 13.25% (0-44%) in non-responders. Non-responders were more likely to be under 1 year. Two patients required dose increases and one patient non-adherence to dose was identified. Four patients on repeat testing were responsive to aspirin by laboratory tests. The rate of aspirin non-response on laboratory testing in this cohort of patients was 23% and resulted in therapeutic intervention in 10%.

Outcomes after Biventricular Repair Using a Conduit between the Right Ventricle and Pulmonary Artery in Infancy.

This study investigated the outcomes of biventricular repair using right ventricle to pulmonary artery (RV-PA) conduit placement in patients aged <1 year. Patients aged <1 year who underwent biventricular repair using an RV-PA conduit between 2011 and 2020 were included in this study. The outcomes of interest were death from any cause, conduit reintervention, and conduit dysfunction (peak velocity of ≥3.5 m/sec or moderate or severe regurgitation). In total, 141 patients were enrolled. The median age at initial conduit implantation was 6 months. The median conduit diameter z-score was 1.3. The overall 5-year survival rate was 89.6%. In the multivariable analysis, younger age (p=0.006) and longer cardiopulmonary bypass time (p=0.001) were risk factors for overall mortality. During follow-up, 61 patients required conduit reintervention, and conduit dysfunction occurred in 68 patients. The 5-year freedom from conduit reintervention and dysfunction rates were 52.9% and 45.9%, respectively. In the multivariable analysis, a smaller conduit z-score (p<0.001) was a shared risk factor for both conduit reintervention and dysfunction. Analysis of variance demonstrated a nonlinear relationship between the conduit z-score and conduit reintervention or dysfunction. The hazard ratio was lowest in patients with a conduit z-score of 1.3 for reintervention and a conduit z-score of 1.4 for dysfunction. RV-PA conduit placement can be safely performed in infants. A significant number of patients required conduit reintervention and had conduit dysfunction. A slightly oversized conduit with a z-score of 1.3 may reduce the risk of conduit reintervention or dysfunction.

Impact of Anatomical Sub-types and Shunt Types on Aortopulmonary Collaterals in Hypoplastic Left Heart Syndrome

This study aims to clarify the relation of development of aortopulmonary collateral arteries (APCs) with anatomical sub-types and the shunt types at Norwood procedure in patients with hypoplastic left heart syndrome (HLHS). A total of 140 patients with HLHS who completed 3 staged palliation between 2003 and 2019 were included. Incidence of APCs and corresponding interventions were examined using angiogram by cardiac catheterization, with respect to the anatomical sub-types and shunt types. Totally, APCs were observed in 87 (62%) of the patients; pre-stage II in 32 (23%), pre-stage III in 64 (46%), and after stage III in 40 (29%). The incidence of APCs before stage II was significantly higher in patients with aortic atresia/mitral atresia (AA/MA) compared with other sub-types (P = 0.022). Patients with right ventricle to pulmonary artery conduit (RVPAC) had a higher incidence of APCs originating from the descending aorta, compared with those with modified Blalock-Taussig shunt (20% vs 2%, P= 0.002). Interventions for APCs were performed in 58 (41%) patients; before stage II in 10 (7%), after stage II in 7 (5%), before stage III in 22 (16%), and after stage III in 32 (23%). Patients with AA/MA had more interventions before stage II (P= 0.019), and patients with aortic stenosis/mitral stenosis (AS/MS) had a lower incidence of interventions after stage III (P= 0.047). More than half of the patients with HLHS developed APCs. Before stage II, patients with AA/MA sub-type had a higher incidence of APCs, and those with RVPAC had significantly more APCs from the descending aorta.

A Ring-Reinforced Right Ventricle to Pulmonary Artery Conduit is Associated with Better Regional Mechanics after Stage I Norwood Operation

Background: The right ventricle to pulmonary artery conduit (RVPAC) may impair right ventricular (RV) function in patients with functional single right ventricles. Modification of the RVPAC using a ring-reinforced end with dunked insertion into the RV through a limited ventriculotomy may reduce the impact on RV function. We compared RV segmental strain between patients with a traditional RVPAC and ring-reinforced RVPAC using feature tracking cardiovascular magnetic resonance (CMR) imaging. Methods: Patients with CMR examinations after Stage I operation with RVPAC between 2000 and 2018 were reviewed. Ventricular mass, volumes, late gadolinium enhancement (LGE), and peak radial and circumferential strain of the 4 segments near the RVPAC insertion site were analyzed. Results: The study included 71 CMR examinations in 61 patients (30 traditional RVPAC, 31 ring-reinforced RVPAC). Prior to Stage II, the ring-reinforced RVPAC group had better peak radial strain and circumferential strain in 1 of 4 segments proximal to the RVPAC insertion site compared to the traditional RVPAC group. Prior to Stage III operation, the ring-reinforced group had better peak radial and circumferential strain in 2 of 4 segments. LGE at the RVPAC insertion site was observed in 97% of patients before Stage II and 95% of patients before Stage III. RVPAC type and regional strain were not associated with transplant-free survival during a median follow-up of 6.3 years. Conclusions: Compared to a traditional RVPAC, the ring-reinforced RVPAC is associated with improved regional mechanics at the conduit insertion site. Further investigation of long-term outcomes after ring-reinforced RVPAC is warranted.

Covered Stents in the Management of Aortic Coarctation and Right Ventricular Outflow Tract Obstruction.

To review the use of covered stents in the treatment of coarctation of the aorta (CoA) and right ventricle to pulmonary artery (RV-PA) conduit obstruction. The only commercially available covered stent approved for treatment of CoA and dysfunctional RV-PA conduits is the covered Cheatham-Platinum stent (CCPS). Early outcomes have demonstrated its safety and have suggested its efficacy in treating or preventing aortic wall injury (AWI) or conduit disruption. A recent study of CCPS use for CoA reported a progressive risk of stent fracture over time and a risk of AWI despite the purported protection that the CCPS provides. The use of other covered stents has been reported, but large, systematic studies are lacking. CCPS use may reduce but does not eliminate the risk of conduit disruption or AWI. Structural limitations of the CCPS may predispose it to stent fracture. Access to a broad range of covered stents continues to be an unmet need in the field of congenital interventional cardiology.

Influence of Shunt Type on Survival and Right Heart Function after the Norwood Procedure for Aortic Atresia

The study objective was to compare the results after Norwood procedure between modified Blalock-Taussig shunt (MBTS) and right ventricle-to-pulmonary artery conduit (RVPAC) according to Sano in patients with hypoplastic left heart syndrome (HLHS) and aortic atresia (AA). A total of 146 neonates with HLHS and AA who underwent the Norwood procedure at our institution between 2001 and 2020 were divided into 2 groups according to shunt type (MBTS or RVPAC). Survival after the Norwood procedure was compared between the groups. Longitudinal right ventricular and tricuspid valve function in each group were evaluated using cubic splines method. RVPAC was performed in 103 patients and MBTS in 43 according to surgeon preference. There were no differences in the 30-day mortality rates (16.5% vs 16.3%, P =0.973). Survival at 0.5, 1 and 3 years was 79.6%, 74.6%, and 68.9% in RVPAC and 66.8%, 64.3%, and 58.5% in MBTS (P = 0.293). Among 23 patients undergoing tricuspid valve procedure, different mechanisms of tricuspid regurgitation were observed between the groups. Longitudinal analysis revealed greater prevalence of late right ventricular dysfunction in RVPAC patients. In 77 patients who completed Fontan procedure, the postoperative N-terminal pro B-type natriuretic peptide value was significantly higher in RVPAC vs MBTS (554 vs 276 ng/L, P = 0.007). No survival advantage of RVPAC over MBTS was observed in neonates with HLHS and AA undergoing the Norwood procedure. Longitudinal analysis demonstrated a greater prevalence of right ventricular dysfunction and higher N-terminal pro B-type natriuretic peptide values during late follow-up in patients with RVPAC.

Outcomes Following Heterotopic Placement of Right Ventricle to Pulmonary Artery Conduits

We sought to evaluate the outcomes following right ventricle to pulmonary artery (RV-PA) conduit placement in pediatric patients, excluding those with a RV-PA conduit for the Ross procedure which is associated with improved conduit durability, partly related to its orthotopic position. Outcomes for 119 patients who underwent RV-PA conduit placement at a single institution from January 2004 to December 2016 were reviewed. Primary outcome measures were reintervention-free survival (RFS) and overall survival. Survival analyses were performed using the Kaplan-Meier method, and risk factors associated with reintervention were evaluated. The median age at the time of conduit placement was 6 months (interquartile range, IQR: 1-14), and the median length of follow-up was 63 months (range: 0-156). During follow-up, 39 patients required conduit-related reintervention, while 6 patients died perioperatively with an overall survival of 90% at 10 years. Among the remaining 113 patients, the RFS at one, five, and ten years was 91% (84%-95%), 72% (60%-80%), and 33% (16%-50%), respectively. The median time to conduit replacement in the series was 43.5 months (IQR: 19.3-76.2). The use of a pulmonary homograft was associated with improved RFS (P = .03), and this was particularly pronounced in comparison with aortic homografts in neonates. Infection was the indication for replacement in only one patient. The majority of the conduits placed during the neonatal period required conduit replacement before the age of five years. Endocarditis was not a common indication for replacement. In neonates and infants, we prefer pulmonary homografts for most indications.

Results of Less Than 5-mm Right Ventricle-Pulmonary Artery Conduits in Single Ventricle Palliation

Our programmatic approach to single ventricle (SV) neonatal palliation has evolved to using smaller-size right ventricle to pulmonary artery (RV-PA) conduits for pulmonary blood flow. Therefore, we sought to compare the early outcomes of less than 5-mm versus 5-mm RV-PA conduits in SV patients undergoing neonatal palliation. We performed a retrospective review of SV patients who had neonatal palliation with either a less than 5-mm or 5-mm RV-PA connection, constructed using a waterproof, breathable fabric membrane graft (Gore-Tex, Flagstaff, AZ). Data before, during, and after surgery were analyzed using SPSS software. A total of 26 patients in group 1 (n= 11; <5 mm) and group 2 (n= 15; 5 mm) were operated on, with a mean follow-up of 13 months. Statistical differences (P ≤ .05) were noted with renal near-infrared spectroscopy (mean, 56 versus 44), and oxygen saturation at discharge (mean, 80% versus 85%) in groups 1 and 2, respectively. We found no significant difference in patient weight, peak lactate, cerebral near-infrared spectroscopy, length of intubation, length of hospitalization, or need for RV-PA conduit intervention after stage 1 along with age, branch PA sizes, or need for PA plasty at bidirectional Glenn between groups. Our early results of less than 5-mm conduits support further exploration into the tailoring of the RV-PA conduit size for each patient. A smaller-diameter conduit may improve systemic cardiac output and net oxygen delivery. Larger patient cohorts and longer follow-up with assessment of pulmonary artery growth are warranted to guide clinical practice.

Evaluation of personalized right ventricle to pulmonary artery conduits using in silico design and computational analysis of flow.

ObjectivesRight ventricle to pulmonary artery (RV-PA) conduits are required for the surgical management of pulmonary atresia with ventricular septal defect and truncus arteriosus. Bioengineered RV-PA connections may address some of the shortcomings of homografts and xenografts, such as lack of growth potential and structural deterioration and may be manufactured to accommodate patient-specific anatomy. The aim of this study was to develop a methodology for in silico patient-specific design and analysis of RV-PA conduits.MethodsCross-sectional imaging was obtained from patients with truncus arteriosus (n = 5) and pulmonary atresia with ventricular septal defect (n = 5) who underwent complete repair with a RV-PA conduit. Three-dimensional models of the heart were constructed by segmentation of the right ventricle, existing conduit, branch pulmonary arteries, and surrounding structures. A customized conduit design for each patient was proposed. Computational fluid dynamics analysis was performed and outputs, including wall shear stress and energy loss, were used to compare the performance of the existing conduits and the customized geometries.ResultsIn this study, a methodology for patient-specific analysis of RV-PA conduit in silico was developed. The results of simulations for 10 patients showed between 23% and 56% decrease in the average wall shear stress and between 24% and 87% reduction in average power requirements in customized designs compared with the stenosed conduits, translating into better hemodynamic performance.ConclusionsCreation of an optimal conduit for an individual patient can be achieved using surgeon-guided design and computational fluid dynamics analysis. Manufacture of personalized RV-PA conduits may obviate the need for surgical customization to accommodate existing materials and provide superior long-term outcomes.

Current Challenges and Emergent Technologies for Manufacturing Artificial Right Ventricle to Pulmonary Artery (RV-PA) Cardiac Conduits.

Despite advances in modern surgery, congenital heart disease remains a medical challenge and major cause of infant mortality. Valved conduits are routinely used to surgically correct blood flow in hearts with congenital malformations by connecting the right ventricle to the pulmonary artery (RV-PA). This review explores the current range of RV-PA conduits and describes their strengths and disadvantages. Homografts and xenografts are currently the primary treatment modalities, however both graft types have limited biocompatibility and durability, and present a disease transmission risk. Structural deterioration of a replaced valve can lead to pulmonary valve stenosis and/or regurgitation. Moreover, as current RV-PA conduits are of a fixed size, multiple subsequent operations are required to upsize a valved conduit over a patient's lifetime. We assess emerging biomaterials and tissue engineering techniques with a view to replicating the features of native tissues, including matching the durability and elasticity required for normal fluid flow dynamics. The benefits and limitations of incorporating cellular elements within the biomaterial are also discussed. Present review demonstrates that an alignment of medical and engineering disciplines will be ultimately required to produce a biocompatible and high-functioning artificial conduit.

Tetralogy of Fallot and abnormal coronary artery: use of a prosthetic conduit is outdated.

Repair of tetralogy of Fallot (ToF) can be challenging in the presence of an abnormal coronary artery (CA) in 5-12% of cases. The aim of this study was to report our experience with ToF repair without the systematic use of a right ventricle-to-pulmonary artery (RV-PA) conduit. We conducted a monocentric retrospective study from 2000 to 2016, including 943 patients with ToF who underwent biventricular repair, of whom 8% (n = 76) presented with an abnormal CA. Mean follow-up time was 50 months (1 month-18 years). The most frequent CA anomaly was the left descending artery arising from the right CA (n = 47, 61.8%). The median age at repair was 7.7 months (1.8 months-16 years). Thirteen patients (17%) required prior palliation, mostly systemic pulmonary shunts for anoxic spells in the neonatal period. Surgical repair allowed us to preserve the annulus in 40 patients (53%) by combining PA trunk plasty, commissurotomy and infundibulotomy under the abnormal CA. If the annulus had to be opened (n = 35, 46%), a transannular patch was inserted after a vertical incision of the PA trunk and extended obliquely on the RV over the anomalous crossing CA (with an infundibulotomy under the abnormal CA). Three patients (4%) required the insertion of an RV-PA conduit (1 valved tube and 2 RV-PA GORE-TEX tubes with annulus conservation). The early mortality rate was 4% (n = 3); none of the deaths was coronary related. Four patients (5%) required reoperation (2 early and 2 late reoperations) for residual pulmonary stenosis, 3 of whom had annulus preservation during the initial repair. The mean RV/left ventricle (LV) pressure ratio and an RV/LV pressure ratio >2/3 were identified as risk factors for right ventricular outflow tract (RVOT) reinterventions (P = 0.0026, P = 0.0085, respectively), RVOT reoperations (P = 0.0002 for both) and reoperation for RVOT residual stenosis (P = 0.0002, P = 0.0014, respectively). Two patients underwent pulmonary valve replacement. Freedom from late reoperation was 100% at 1 year, 97% at 5 years and 84% at 10 and 15 years. Repair of ToF and abnormal CA can be performed without an RV-PA conduit, with an acceptable low reintervention rate. The high early mortality rate in this series remains a concern. If any doubt remains about the surgical relief of the RVOT obstruction, the RV/LV pressure ratio should always be measured in the operating room.

RF73 RIGHT VENTRICULAR OUTFLOW TRACT RECONSTRUCTION IN PEDIATRIC CARDIAC SURGERY: FEDERICO II 10-YEARS EXPERIENCE

Background and Aim: Surgical repair of congenital heart defects involving reconstruction of the right ventricle outflow tract sometimes requires implantation of a right ventricle to pulmonary artery (RV-PA) conduit. To date, the ideal conduit is yet to be found so different kinds of prosthesis are usually used. It will be presented the 10-years experience with the different PA-RV conduits used at our institution. Methods: From 2007 to 2018, 92 RV-PA conduit implant procedures were performed on 75 children (58 Contegra®, 12 Fresh Homografts and 22 Hancock®). Clinical data were retrospectively collected from medical records and then they were matched for comparison using propensity score. Pediatric Risk of Mortality score, the day of withdrawal of inotropic drugs, the length of the intensive care unit stay and of the hospital stay were used to assess postoperative morbidity. Results: No significant difference was observed when considering the operative data for anesthesia, the intraoperative inotropic support, the perioperative complication rate or the postoperative morbidity and mortality. Length of surgery, of cardiopulmonary bypass, of aortic clamping and the intraoperative and postoperative blood loss was significantly lower in the Homograft group. There were no differences in the reoperation free survival between Contegra® and Hancock® groups but a significantly higher reoperation free survival was observed in Homograft group. Conclusion: RV-PA conduit replacement can be achieved with a low surgical morbidity or mortality with any type of conduit but Homografts seem to be related to a better intraoperative and postoperative outcomes especially due to their long life.

Multicenter Analysis of Early Childhood Outcomes After Repair of Truncus Arteriosus

Literature describing morbidity and mortality after truncus arteriosus repair is predominated by single-center reports. We created and analyzed a multicenter dataset to identify risk factors for late mortality and right ventricle-to-pulmonary artery (RV-PA) conduit reintervention for this patient population. We retrospectively collected data on children who underwent repair of truncus arteriosus without concomitant arch obstruction at 15 centers between 2009 and 2016. Cox regression survival analysis was conducted to determine risk factors for late mortality, defined as death occurring after hospital discharge and greater than 30 days after operation. Probability of any RV-PA conduit reintervention was analyzed over time using Fine-Gray modeling. We reviewed 216 patients with median follow-up of 2.9 years (range, 0.1 to 8.8). Operative mortality occurred in 15 patients (7%). Of the 201 survivors there were 14 (7%) late deaths. DiGeorge syndrome (hazard ratio [HR], 5.4; 95% confidence interval [CI], 1.6 to 17.8) and need for postoperative tracheostomy (HR, 5.9; 95% CI, 1.8 to 19.4) were identified as independent risk factors for late mortality. At least one RV-PA conduit catheterization or surgical reintervention was performed in 109 patients (median time to reintervention, 23 months; range, 0.3 to 93). Risk factors for reintervention included use of pulmonary or aortic homografts versus Contegra (Medtronic, Inc, Minneapolis, MN) bovine jugular vein conduits (HR, 1.9; 95% CI, 1.2 to 3.1) and smaller conduit size(HR per mm/m2, 1.05; 95% CI, 1.03 to 1.08). In a multicenter dataset DiGeorge syndrome and need for tracheostomy postoperatively were found to be independent risk factors for late mortality after repair of truncus arteriosus, whereas risk of conduit reintervention was independently influenced by both initial conduit type and size.

The "double dunk" technique for a right ventricle to pulmonary artery conduit implantation during the Norwood procedure reduces unintended shunt-related events.

The introduction of a right ventricle to pulmonary artery conduit (RVPAc) during the Norwood procedure (NP) for hypoplastic left heart syndrome (HLHS) resulted in a higher survival rate, but also in an increased number of unintended pulmonary and shunt-related interventions. To analyse how several modifications employed in RVPAc implantation during NP may influence the interstage course, unintended surgical or catheter-based interventions, and pulmonary artery development in a cohort of patients with HLHS. We retrospectively analysed three groups of non-selected, consecutive neonates who underwent the NP between 2011 and 2014, with different RVPAc surgical techniques employed: Group I (n = 32) - left RVPAc with distal homograft cuff, Group II (n = 28) - right RVPAc with distal homograft cuff, and Group III (n = 41) - "double dunk," right reinforced RVPAc (n = 41). There were no intergroup differences in terms of age, weight, prevalence of aortic atresia, diameter of the ascending aorta, deep hypothermic circulatory arrest time, and hospital mortality rate (9.3% vs. 14.2% vs. 7.3%, respectively). There was a significant difference between the groups in the number of catheter-based interventions during the interstage period (34% vs. 25% vs. 0%, respectively, p < 0.05) and/or concomitant surgical interventions (17.2% vs. 4.1% vs. 2.6%, respectively). The diameter of the pulmonary arteries was most homogenous in the third group. The modified strategy of using the "double dunk," right reinforced RVPAc during the NP for HLHS significantly reduces the number of unintended catheter-based and surgical shunt-related reinterventions during the interstage period. This technique allows a more homogenous development of pulmonary arteries before the second, surgical stage.

Right ventricular outflow tract reintervention after primary tetralogy of Fallot repair in neonates and young infants

ObjectiveTo assess the outcomes following primary tetralogy of Fallot (TOF) repair in neonates and young infants with pulmonary stenosis (PS) and pulmonary atresia and compare differences in reintervention on the right ventricular outflow tract (RVOT) among those undergoing valve sparing repair (VSR), transannular RVOT patch (TAP), and right ventricle–to–pulmonary artery (RV-PA) conduit surgeries. MethodsData were collected retrospectively in 101 patients who underwent TOF repair over a 10-year period between January 2005 and September 2015. The primary endpoint was reintervention on the RVOT, defined as a surgical procedure or cardiac catheterization–based RVOT reintervention. ResultsForty-three patients had TOF/PS, of whom 24 (56%) underwent TAP and 19 (44%) underwent VSR. Fifty-eight patients had TOF/PA, 14 (24%) underwent TAP and 44 (76%) underwent RV-PA conduit repair. Overall patient mortality was 2.9% (3 of 101). Thirty-three patients underwent surgical reintervention, and 52 underwent catheterization-based reintervention. Patients with TOF/PA who underwent RV-PA conduit repair had a higher surgical reintervention rate than those who underwent TAP (45% vs 21%). Patients with TOF/PSs undergoing VSR with a lower median birth weight (2.5 kg vs 3.7 kg) required more surgical reintervention. ConclusionsNeonatal TOF repair can be performed with low mortality but frequent RVOT reinterventions. Surgical reintervention is earlier and the rate is higher among patients with TOF/PA undergoing RV-PA conduit repair compared with those undergoing TAP. Although there were no overall differences in RVOT reintervention rate between patients with TOF/PS undergoing VSR and those undergoing TAP, a lower birth weight in the patients undergoing VSR is associated with a higher surgical reintervention rate.

A reinforced right-ventricle-to-pulmonary-artery conduit for the stage-1 Norwood procedure improves pulmonary artery growth

ObjectiveTo compare early postoperative outcomes, angiographic, and intervention findings and 1-year survival between 2 groups of infant patients: those receiving a standard right-ventricle-to-pulmonary-artery (RV-PA) conduit versus a ring-reinforced RV-PA conduit, in undergoing Norwood stage-1 surgery for hypoplastic left heart syndrome (HLHS). The technique of using such a ring-reinforced graft, placed through a limited ventriculotomy, has theoretic advantages in preserving right ventricular function, compared with the standard technique of RV-PA conduit creation. MethodsThis retrospective cohort study was performed between July 2006 and July 2013. A total of 87 patients with HLHS underwent Norwood stage-1 surgery during this period; 48 received a standard nonreinforced RV-PA conduit; 39 received a ring-reinforced conduit. Primary and secondary outcomes were survival and need for cardiac reintervention up to age 12 months. ResultsNo difference was found in transplant-free survival by age 12 months (87% ring-reinforced vs 73% nonreinforced, P = .12). The group with the nonreinforced, versus ring-reinforced, grafts had more interventions in the first year (69% vs 35%, respectively; P < .01). Before stage 2, the pulmonary artery pulse pressure was greater in the group with ring-reinforced grafts (9.1 ± 4.1 vs 4.8 ± 3.1 mm Hg, P < .001), with no difference in mean pressure (15.2 ± 3.32 vs 14.3 ± 3.48 mm Hg, P = .27). The corrected pulmonary artery index (Nakata) was greater in the group with ring-reinforced grafts (213 ± 76 vs 134 ± 68 mm2/m2, P < .0001). ConclusionsA ring-reinforced conduit is associated with reduced intervention, as well as higher pulse pressures and improved pulmonary artery growth, in infants undergoing stage-1 palliation for HLHS.

Angioplasty of Obstructed Homograft Conduits in the Right Ventricular Outflow Tract With Ultra-Noncompliant Balloons

Angioplasty and stent placement in right ventricle-to-pulmonary artery (RV-PA) conduits have been shown to prolong the functional lifespan of a conduit. Safety and efficacy of angioplasty of obstructed RV-PA homografts using ultra-noncompliant (UNC) or ultrahigh-pressure balloons are unknown. From 2004 to 2012, 70 patients underwent 76 procedures for angioplasty of RV-PA homografts with UNC Atlas balloons. The UNC group was compared with a partially contemporaneous control cohort of 81 patients who underwent 84 angioplasty procedures with conventional balloons. Acute hemodynamic changes after angioplasty of homografts with UNC balloons included significantly reduced RV:Ao pressure ratio (P=0.02) and right ventricular outflow tract gradients (P≤0.001). Balloon waist resolution was more frequently achieved with UNC balloons (P=0.04), and balloon rupture occurred less often (P<0.001). Conduit tears of any severity occurred in 22% of patients overall and were more common in the UNC group (P=0.001). Patients with any conduit tear had significantly greater reduction in their RV:Ao pressure ratio (P<0.001) and right ventricular outflow tract gradient (P=0.004) than those with no tear. There were 4 unconfined tears, all in the UNC group, with no acute decompensations or deaths and only 1 patient who required surgical management. RV-PA conduit tears are common in patients undergoing angioplasty, but clinically important tears, which only occurred during UNC angioplasty in this series, were uncommon. UNC balloons can be used to good effect with significant reduction in right ventricular outflow tract gradient and the RV:Ao ratio when compared with conventional balloons.

Treatment of right ventricle to pulmonary artery conduit stenosis in infants with hypoplastic left heart syndrome

To determine the incidence of right ventricle-to-pulmonary artery (RV-PA) conduit stenosis after the Norwood I operation in patients with hypoplastic left heart syndrome (HLHS), and to determine whether the treatment strategy of RV-PA conduit stenosis has an influence on interstage and overall survival. Ninety-six patients had a Norwood operation with RV-PA conduit between 2002 and 2011. Details of reoperations/interventions due to conduit obstruction prior to bidirectional superior cavopulmonary anastomosis (BSCPA) were collected. Overall pre-BSCPA mortality was 17%, early mortality after Norwood, 6%. Early angiography was performed in 34 patients due to desaturation at a median of 8 days after the Norwood operation. Fifteen patients (16%) were diagnosed with RV-PA conduit stenosis that required treatment. The location of the conduit stenosis was significantly different in the patients with non-ringed (proximal) and the patients with ring-enforced conduit (distal), P = 0.004. In 6 patients, a surgical revision of the conduit was performed; 3 of them died prior to BSCPA. Another 6 patients had a stent implantation and 3 were treated with balloon dilatation followed by a BSCPA in the subsequent 2 weeks. All patients who were treated interventionally for RV-PA conduit obstruction had a successful BSCPA. Patients who received a surgical RV-PA conduit revision had a significantly higher interstage (P = 0.044) and overall mortality (P = 0.011) than those who received a stent or balloon dilatation of the stenosis followed by an early BSCPA. RV-PA conduit obstruction after Norwood I procedure in patients with HLHS can be safely and effectively treated by stent implantation, balloon dilatation and early BSCPA. Surgical revision of the RV-PA conduit can be reserved for patients in whom an interventional approach fails, and an early BSCPA is not an option.

Right Ventricle to Pulmonary Artery Conduit Reoperations in Patients With Tetralogy of Fallot or Pulmonary Atresia Associated With Ventricular Septal Defect

The short lifespan of right ventricle-to-pulmonary artery (RV-PA) conduits used in repairs of complex congenital heart defects makes future surgical replacement inevitable. Percutaneous pulmonary valve implantation (PPVI) now offers an attractive alternative to surgery in some patients. The objectives of this study were to examine the pattern of conduit reoperations, the factors affecting conduit longevity, and to discuss the role of PPVI in these patients. Forty-nine patients (mean age 27 ± 8 years) with pulmonary atresia or pulmonary stenosis with tetralogy of Fallot who underwent surgery for RV-PA conduits from September 1974 to October 2011 were reviewed. A total of 106 RV-PA conduits were implanted, 57 of which were replacements. Second, third, and fourth conduits were required during the follow-up period in 39, 16, and 2 patients, respectively. Freedom from reoperation at 10 years for the first, second, and third conduits was 50%, 74%, and 86%, respectively. Significant independent predictors of shorter conduit longevity included smaller conduit and conduit type (homograft and other vs Dacron). Furthermore, a significant proportion (32 of 57 [56%]) of conduit replacements took place from ages 9 to 18 years. There were 37 adults whose current existing conduits had not yet failed, with 73% (27 of 37) potentially suitable in the future for PPVI on the basis of conduit size of 16 to 27mm. In conclusion, multiple RV-PA conduit revisions were required in patients who survived to adulthood, with many replacements taking place during adolescence. Most conduits in this adult cohort met size criteria for PPVI, thereby offering these patients a potential alternative to surgical intervention for conduit failure.

The Norwood Procedure: In favor of the RV-PA Conduit

Evolution of the Norwood procedure has culminated in there currently being three treatment strategies available for initial management: the 'classical' Norwood (utilizing a Blalock-Taussig shunt), the Norwood with right-ventricle to pulmonary artery (RV-PA) conduit, and the 'hybrid' Norwood procedure utilizing bilateral pulmonary artery banding and ductal stenting. Each variant has its potential advantages and disadvantages, and this paper looks to examine the evidence in favor of each strategy, with emphasis on the supportive data for the RV-PA conduit. The 'classical' procedure has the benefit of the greatest accumulated surgical experience and avoids any incision into the ventricle. However, the diastolic run-off of the Blalock-Taussig shunt can cause hemodynamic instability and unpredictable coronary steal phenomenon. The RV-PA conduit has the advantage of maintaining diastolic pressure with a more stable postoperative course, but at the cost of a ventriculotomy that may have detrimental long-term sequelae. The 'hybrid' procedure has the advantage of avoiding cardiopulmonary bypass, but does not always secure coronary blood flow and has a high inter-stage morbidity and reintervention rate. The evidence shows that each technique may have its place in future management, and that treatment algorithms could emerge that direct the choice of procedure for specific patient groups.