Right ventricular outflow tract reconstruction with the Contegra bovine jugular vein conduit: a word of caution

Experience and Outcomes of Surgically Implanted Melody Valve in the Pulmonary Position

BACKGROUND

Multiple congenital cardiac malformations require pulmonary valve replacement and/or right ventricular outflow (RVOT) reconstruction. Pulmonary valve replacement remains challenging in children owing to the limited growth potential of prosthetic valves. We evaluated outcomes in patients undergoing surgical implantation of a Melody valve in the RVOT.

METHODS

Data were retrospectively collected for 23 patients undergoing surgical Melody valve implantation at Boston Children's Hospital between 2009 and 2019. We assessed postoperative valve function, reintervention rates, and mortality.

RESULTS

Median age was 1.7 years (range, 2 months to 6 years); 12 patients were aged greater than 2 years (52%). Diagnosis was tetralogy of Fallot in 15 patients (65%); 15 had a prior RVOT operation (65%). The Melody valve was dilated before surgery to a median diameter of 14 mm (range, 10-20 mm). No patients had acute pulmonary regurgitation. One required transcatheter RVOT reintervention before discharge. Median follow-up was 3.7 years (range, 0.02-8.7 years) with moderate or greater pulmonary regurgitation in 2 patients. Catheter-based interventions (mean, 0.83 ± 1.07/patient) occurred at a median of 1 year (range, 16 days to 5.4 years) and included valve expansion for somatic growth (n = 10) and subsequent valve-in-valve replacement (n = 3). Three patients (13%) required surgical valve explant or replacement at a median of 1.0 year (range, 0.6-3.7 years) for Melody-specific indications. One-, 3-, and 5-year freedom from Melody-driven reoperation was 90%, 90%, and 83%, respectively.

CONCLUSIONS

The Melody valve can be surgically implanted in the RVOT of young patients with acceptable early results. These valves can be successfully dilated through transcatheter reintervention to accommodate growth.

Right ventricular outflow tract reconstruction with the Labcor® stentless valved pulmonary conduit

OBJECTIVES

The right ventricular outflow tract reconstruction is a common necessity in congenital cardiac surgery. As homograft availability is limited, alternatives need to be evaluated. The Labcor® conduit consists of a porcine tricomposite valve assembled inside a bovine pericardium tube. This study presents intermediate-term results for its utilization for right ventricular outflow tract reconstruction.

METHODS

Labcor conduits were implanted in 53 patients (February 2009-July 2016). We analysed perioperative data, freedom from conduit failure and risk factors for conduit dysfunction.

RESULTS

The most common diagnosis was Tetralogy of Fallot (n = 20, 37.7%). The median age at surgery was 10.0 [interquartile range (IQR) 4.9-14.3] years. Pulmonary artery plasty (n = 37, 69.8%) and augmentation of the right ventricular outflow tract (n = 16, 30.2%) were often part of the procedure. The median conduit size was 21 (range 11-25) mm. There was no in-hospital death. The median follow-up after surgery was 4.6 (IQR 3.4-5.6) years. Fourteen patients (27.5%) developed conduit failure with stenosis being the main cause. Freedom from conduit failure was 98.0% at 2 and 80.5% at 5 years. The median longevity of the conduit was 7.4 years (95% confidence interval 5.1-9.8 years). Younger age and smaller conduit size were related to conduit failure.

CONCLUSIONS

Utilization of the Labcor conduit revealed acceptable intermediate-term results. The conduit appeared to be functioning sufficiently well within the first 5 years in the majority of patients. The higher rate of failure concerning smaller conduits might be associated with somatic outgrowth; however, conduit degeneration as common and long-term outcome still needs to be evaluated.

Outcomes of Prosthetic Valved Conduits for Right Ventricular Outflow Tract Reconstruction

There are limited data regarding the implantation of prosthetic valved conduits for right outflow tract reconstruction in pediatric patients in China. A retrospective review of 128 patients undergoing conduits implantation with a median follow-up of 33.3 months (range, 3.3 months to 10.1 years) was performed between 2009 and 2018. Multivariate Cox regression model was used to analyze the risk factors for mortality, reintervention and endocarditis. Freedom from reintervention and endocarditis were plotted using the Kaplan-Meier curve. Hospital mortality was 7.8%, and the late mortality was 3.1%. Patient survival at 1, 5 and 10 years was 92.2%, 87.1% and 84.3%, respectively. Freedom from reintervention at 1 and 5 years was 94.1% and 60.9%. Small size conduit (p = 0.019) and previous palliation (p < 0.001) were predictive of reintervention. Ten conduits developed endocarditis at a median of 4.8 years after implantation. Freedom from endocarditis at 1, 5 and 10 years was 99.1%, 93.0% and 58.0%, respectively. Diffuse stenosis of the conduit (p = 0.003) was an independent risk factor for late endocarditis. Both bovine jugular venous conduits and bovine pericardial prosthetic conduits are associated with acceptable outcomes. Reintervention remains high in patients who have smaller size conduit and undergo previous palliation. It is plausible that the suboptimal flow may be one of major mechanisms involved in the development of late endocarditis.

Contegra versus pulmonary homograft for right ventricular outflow tract reconstruction in newborns

OBJECTIVES

Pulmonary homografts are standard alternatives to right ventricular outflow tract reconstruction in congenital heart surgery. Unfortunately, shortage and conduit failure by early calcifications and shrinking are observed for small-sized homografts in younger patients. In neonates, Contegra® 12 mm (Medtronic Inc., Minneapolis, Minnesota, United States of America) could be a valuable alternative, but conflicting evidence exists. There is no published study considering only newborns with heterogeneous pathologies. We retrospectively compared the outcomes of these two conduits in this challenging population.

METHODS

Patients who underwent a right ventricular outflow tract reconstruction between January 1992 and December 2014 at the Hôpital Universitaire des Enfants Reine Fabiola were included. We retrospectively collected and analysed demographic, echocardiographic, surgical, and follow-up data.

RESULTS

Of the 53 newborns who benefited from a right ventricular outflow tract reconstruction during the considered period, 30 received a Contegra 12 mm (mean age 15 ± 8 days), and 23 a small (9-14 mm) pulmonary homograft (mean age 10 ± 7 days). Overall mortality was 16.6% with Contegra versus 17.4% in the pulmonary homograft group (p = 0.98 log-rank). Operative morbidity and early re-operation for conduit failure were not significantly different between the two groups. Mean follow-up in this study is 121 ± 74 months. Survival free from re-operation was not different between the two groups (p = 0.15). Multivariable analysis showed that weight and significant early gradient were factors associated with anticipated conduit failure.

CONCLUSIONS

Contegra 12 mm is a valid alternative to small pulmonary homografts in a newborn patient population.

TRIAL REGISTRATION

NCT03348397.

Outcomes of truncus arteriosus repair with bovine jugular vein conduit

Background

In this study, we aimed to evaluate the outcomes of truncus arteriosus repair in patients undergoing Rastelli type truncus arteriosus.

Methods

A total of 13 patients (7 males, 6 females; median age 37 days; range, 16 to 60 days) underwent repair of truncus arteriosus using Contegra conduits between January 2011 and March 2 017. P reoperative d iagnosis w as t runcus a rteriosus type 1 (Edwards-Collett) in eight, type 2 in three, type 3 in one, and type 4 in one patient. Contegra conduits used for operations were 14 mm (n=5), 12 mm (n=7), and 16 mm (n=1).

Results

Early death was seen in two patients (15.4%). The median intensive care and hospital stays were 10 (range, 6 to 14) and 20 (range, 14 to 41) days, respectively. The median follow-up was 36 (range, 2 to 66) months. In four patients (31%), the conduit sizes severely increased during follow-up and reached 23 mm in two patients and 20 mm in one patient, and 18 mm in the other patient. Three patients had moderate distal conduit stenosis. Moderate pulmonary insufficiency was detected in four patients and severe pulmonary insufficiency in one patient. Two patients had moderate truncal valve insufficiency and one patient had moderate residual ventricular septal defect. None of the patients needed reoperation.

Conclusion

Contegra conduit is a good alternative for repair of truncus arteriosus in infants; however close follow-up is necessary, as distal conduit stenosis and conduit dilatation may develop.

Pulmonary valve replacement after right ventricular outflow tract reconstruction with homograft vs Contegra®: a case control comparison of mortality and morbidity

Background

Repair of congenital heart defects involving the right ventricular outflow tract may require the implantation of a right ventricle to pulmonary artery conduit. This conduit is likely to be replaced during childhood. This study compares the operative outcomes of the replacement procedure of Contegra® and homografts in pulmonary position.

Methods

From 1999 to 2016, 82 children underwent 87 right ventricle to pulmonary artery conduit replacements (60 Contegra® and 27 homografts). Demographics, operative and clinical data were obtained through a retrospective review of the medical records. The two groups were matched for comparison using propensity score matching. All the procedures were performed by the same team of surgeons.

Results

No statistically significant difference was observed between the two groups when considering the operative data for anesthesia, surgery, cardiopulmonary bypass and aortic clamping durations. A peroperative complication rate of 13.47% and 15.36% in Contegra® and homograft replacement groups respectively (p value = 0.758) was observed. There was no difference regarding the blood loss and fluid input. No statistically significant difference was observed between the two groups for the post-operative morbidity. We considered the Pediatric Risk of Mortality (PRISM) score, the day of extubation, the day of withdrawal of inotropic drugs, the length of the intensive care unit stay and the length of hospital stay. The overall mortality is 2.3% but there is no statistically significant difference between the two groups.

Conclusion

Right ventricle to pulmonary artery conduit replacement procedure can be achieved with a low surgical morbidity or mortality, not influenced by the type of conduit that is replaced. Therefore, the choice between homograft or Contegra® for right ventricle to pulmonary artery reconstruction should not be influenced by the future surgical risk during the replacement procedure.

Trial registration

NCT03048071. Registered 9 February 2017 (retrospectively registered).

Pulmonary embolism and in situ pulmonary artery thrombosis in paediatrics

Data on paediatric pulmonary embolism (PE) are scarce. We sought to systematically review the current literature on childhood PE and conducted a search on paediatric PE via PubMed (1946–2013) and Embase (1980–2013). There was significant heterogeneity in reported data. Two patterns were noted: classic thromboembolic PE (TE-PE) and in situ pulmonary artery thrombosis (ISPAT). Mean age of presentation for TE-PE was 14.86 years, and 51% of cases were males. The commonest method for diagnosis of TE-PE was contrast CT with angiography (74% of patients). The diagnosis of TE-PE was often delayed. Although 85% of children with TE-PE had an elevated D-dimer at presentation, it was non-discriminatory for the diagnosis. In paediatric TE-PE, the prevalence of central venous catheters was 23%, immobilisation 38%, systemic infection 31% and obesity 13%, elevated Factor VIII or von Willebrand factor levels 27%, Protein C deficiency 17%, Factor V Leiden 14% and Protein S deficiency 7%. In patients with TE-PE, pharmacologic thrombolysis was used in 29%; unfractionated heparin was the most common initial anticoagulant treatment in 64% and low-molecular-weight heparins the most common follow-up treatment in 83%. Duration of anticoagulant therapy was variable and death was reported in 26% of TE-PE patients. In contrast to TE-PE, patients with ISPAT were not investigated systematically for presence of thrombophilia, had more surgical interventions as the initial management and were often treated with anti-platelet medications. This review summarises important data and identifies gaps in the knowledge of paediatric PE, which may help to design future studies.

Histological/Biological Characterization of Decellularized Bovine Jugular Vein

Several deficiencies in currently available right ventricular valved conduits make them problematic for use in infants and children. A solution would be to develop a tissue-engineered valved conduit containing autologous cells. A method was devised to produce a decellularized bovine matrix scaffold for developing a tissue-engineered right ventricular valved conduit. Fresh bovine jugular veins were treated with sodium deoxycholate and Triton X-100. The major structural proteins of the fresh and decellularized jugular venous valves and vessel walls were detected by histological methods. Thickness, water absorption rate, water maintenance rate, disruption strength, and extensibility were determined. Circumferential and radial specimens of valves and vessel walls were subjected to tensile testing. Histological analysis showed that no cell fragments were retained within the decellularized matrix scaffold and the major structural proteins had been retained intact. There were no significant differences in thickness, rates of absorption and maintenance of water, disruption strength, and extensibility between the decellularized and fresh veins. It was concluded that this treatment can successfully remove cellular components while maintaining the major structural components and the histological and biological properties of bovine jugular veins.

Mid-Term Experience with Valved Bovine Jugular Vein Conduits

From June 1999 to January 2004, 43 children underwent implantation of a valved bovine jugular vein conduit and correction of complex congenital heart defects. Median age was 1.98 years (range, 11 days – 13.3 years). There were 7 early deaths (16.3%) unrelated to conduit failure or thrombosis. Median follow-up of 36 survivors was 24 months (range, 1–48 months, quartile range, 12–48 months), total follow-up was 78 patient-years. There were 3 late deaths (8.3%) due to infection, pulmonary thromboembolism, and sudden cardiac arrest after re-operation to repair a right ventricular outflow tract aneurysm. There were 2 conduit explantations due to dysfunction and suspected endocarditis. Three patients underwent balloon dilatation of distal stenoses. The mean peak gradient through the pulmonary anastomosis was 15 mm Hg (range, 3–42 mm Hg) among patients free from re-intervention. No severe valve regurgitation was observed. Freedom from re-intervention was 72% at 48 months. This conduit remains a good alternative to homografts. Causes of distal stenosis must be clarified, guidelines for prophylactic anticoagulation must be created, and the role of percutaneous balloon dilatation established.

A Case Report of Contegra Conduit Dissection With Subsequent Heart Failure

The surgical palliation of several congenital heart defects requires the use of a conduit, particularly between the right ventricle and the pulmonary artery. Contegra, a valved bovine vein conduit, is a conduit frequently used. Pseudoaneurysms, aneurysms, and dissections have seldom been reported with Contegra conduits but are potential complications associated with these conduits. We report a new case of Contegra dissection.

Current status of right ventricular outflow tract reconstruction: complete translation of a review article originally published in Kyobu Geka 2014;67:65-77

Right ventricular outflow tract (RVOT) reconstruction is becoming more prevalent as the number of adult patients who require repeated surgery long after definitive repair of congenital heart defects during childhood has increased. Early primary repair and annulus-preserving surgery have been the two current strategies of RVOT reconstruction from the viewpoint of timing and indications for surgical intervention; however, the long-term outcomes of both procedures remain unknown. Although various materials have been used for pulmonary valve replacement during RVOT reconstruction, deficient durability due primarily to immunological rejection frequently arises, particularly when implanted into young patients. A multicenter study in Japan showed that the clinical outcomes of expanded polytetrafluoroethylene (ePTFE) valved patches/conduits that we developed and manufactured comprised an excellent alternative material for RVOT reconstruction. Such enhanced outcomes might have partly been attributable to the biocompatibility and low antigenicity of ePTFE, and also to the fluid dynamic properties arising from the structural characteristics of a bulging sinus and a fan-shaped valve. However, numerous issues concerning RVOT reconstruction, such as indications for and the timing of definitive repair, as well as the choice of materials for pulmonary valve replacement, must be resolved to achieve better patient prognoses and quality of life. This review describes recent surgical strategies and outstanding issues associated with RVOT reconstruction.

MR and CT imaging of pulmonary valved conduits in children and adolescents: normal appearance and complications

BACKGROUND

The Contegra® is a conduit made from the bovine jugular vein and then interposed between the right ventricle and the pulmonary artery. It is used for cardiac malformations in the reconstruction of right ventricular outflow tract.

OBJECTIVE

To describe both normal and pathological appearances of the Contegra® in radiological imaging, to describe imaging of complications and to define the role of CT and MRI in postoperative follow-up.

MATERIALS AND METHODS

Forty-three examinations of 24 patients (17 boys and 7 girls; mean age: 10.8 years old) with Contegra® conduits were reviewed. Anatomical description and measurements of the conduits were performed. Pathological items examined included stenosis, dilatation, plicature or twist, thrombus or vegetations, calcifications and valvular regurgitation. Findings were correlated to the echographic gradient through the conduit when available.

RESULTS

CT and MR work-up showed Contegra® stenosis (n = 12), dilatation (n = 9) and plicature or twist (n = 7). CT displayed thrombus or vegetations in the Contegra® in three clinically infected patients. Calcifications of the conduit were present at CT in 12 patients and valvular regurgitation in three patients. The comparison between CT and/or MR results showed a good correlation between the echographic gradient and the presence of stenosis in the Contegra®.

CONCLUSION

CT and MR bring additional information about permeability and postoperative anatomy especially when echocardiography is inconclusive. Both techniques depict the normal appearance of the conduit, and allow comparison and precise evaluation of changes in the postoperative follow-up.

An increased incidence of conduit endocarditis in patients receiving bovine jugular vein grafts compared to cryopreserved homograft for right ventricular outflow reconstruction

BACKGROUND

We compared the outcome of patients receiving bovine jugular vein grafts versus cryopreserved homografts for right ventricular outflow tract reconstruction.

METHODS

Between 2000 and 2012, 379 conduits (244 bovine jugular vein grafts, 135 homografts) were implanted in 298 patients (median age 50 months) with a median follow-up of 3.4 years.

RESULTS

Freedom from reoperation at 1, 5, and 7 years was 96.3%, 79.3%, and 64.2% after bovine jugular vein graft and 94.6%, 75.7%, and 68.6% after homograft insertion (p = 0.086). There were 24 cases of endocarditis, 23 associated with bovine jugular vein grafts (9.4%) and 1 associated with a homograft (0.7%; p < 0.001) at median follow-up of 44 months (range, 15 days to 10 years) after conduit implantation. After endocarditis, 15 of 24 conduits were replaced. Three patients had recurrent endocarditis in the revised conduit. Multivariate logistic regression analysis showed age less than 3 years and endocarditis to be significant risk factors associated with conduit replacement. Age more than 3 years and bovine jugular vein grafts were significant risk factors for graft endocarditis. Patients more than 3 years of age at bovine jugular vein graft implantation had significantly lower freedom from reoperation (p = 0.01).

CONCLUSIONS

Compared with homograft conduits, the use of bovine jugular vein grafts for right ventricular outflow tract reconstruction was associated with a significantly higher incidence of bacterial endocarditis and conduit deterioration in older children at our institution. That may influence decision making regarding conduit choice for right ventricular outflow tract reconstruction. Patients and practitioners should be aware of the late risks of bacterial endocarditis after bovine jugular vein graft implantation.

In search of a pediatric cardiac surgeon’s ‘Holy Grail’: the ideal pulmonary conduit

The limited lifespan of all currently available conduits leads to repeat operations and interventional procedures in many children. Each reoperation entails considerable risk to life, expenditure and compromised quality of life as the conduit degenerates. The ideal conduit should be available freely, inexpensive, require no anticoagulation, be resistant to infection, free from thromboembolism, have no gradients or regurgitation and have unlimited durability. This review explores various options as surgeons and researchers endeavor to develop the ideal conduit--which will fulfill all of the above-mentioned criteria. Various currently available conduits are analyzed. Special emphasis is given to tissue-engineered valves and percutaneous valve implantations.

Contegra®conduit: current outcomes and concerns

A variety of congenital cardiac anomalies with severe right ventricular outflow tract (RVOT) obstruction or RVOT interruption require surgical reconstruction from the infundibulum up to the pulmonary artery bifurcation or even into the branches of the pulmonary arteries. Ideally, the conduit or valve required for such reconstruction has to be formed of autologous tissue that grows, resists infection, lasts for the life span of the patient and is readily available in all sizes. Such conduits, however, are not available and although several alternatives have been used, none of which are without potential drawbacks. Contegra valved bovine internal jugular vein conduit (Medtronic Inc., MN, USA) has recently emerged as a promising option for pediatric RVOT reconstruction and has been advocated for its 'off-the-shelf' availability in sizes ranging from 12 to 22 mm, surgical pliability and encouraging short- and mid-term success in experimental animal, as well as clinical studies. This review focuses on the current outcomes of Contegra conduit and highlights some of the major concerns related to the use of this conduit and strategies to tackle these concerns.

Chronic pulmonary valve insufficiency after repaired Tetralogy of Fallot: diagnostics, reoperations and reconstruction possibilities

Complete correction of Tetralogy of Fallot, the most common cyanotic congenital heart defect, has now become routine. However, late residual lesions, primarily chronic pulmonary valve insufficiency, may have a negative impact on right-ventricular function, leading to the need for reoperation to insert a competent valve at the right-ventricular outflow. The diagnostic modalities pertaining to the failing right ventricle, the timing for eventual reintervention and the various surgical reconstruction possibilities of the right-ventricular outflow tract are still controversial and evolving, and are reviewed with a brief overview on current trends and future outlooks.

Bovine valved jugular vein (Contegra™) to reconstruct the right ventricular outflow tract

The right ventricular outflow tract (RVOT) is the part of the circulation located between the right ventricle and the bifurcation of the pulmonary artery. The most cranial part of the right ventriculum infundibulum, the pulmonary anulus, the valve and finally the main trunk of the pulmonary artery are the most important structures. The RVOT is frequently affected in congenital heart diseases, either isolated, or in combination with other cardiac malformations. Current techniques for surgical correction of anomalies of the RVOT include repair and/or replacement of the pulmonary valve often combined with sub- or supravalvular reconstruction. The use of extracardiac conduits (homografts, stented or stentless xenografts) to re-establish continuity between the pulmonary ventricle and pulmonary artery has been an important advance in repair of complex congenital malformations. The Contegra (Medtronic) conduit was introduced as a xenograft tissue for RVOT reconstruction. This conduit has some advantages over homografts including availability for pediatric and adult patient sizes and proximal and distal cuffs allowing for extended reconstruction. The principal late problem related to extracardiac conduit operations is the inevitable need for one or more conduit replacements due to patient somatic growth or progressive conduit degeneration and calcification leading to stenosis.

Adverse results of a decellularized tissue-engineered pulmonary valve in humans assessed with magnetic resonance imaging

OBJECTIVES

Matrix P® and Matrix P plus® tissue-engineered pulmonary valves (TEPV) were offered as an improvement for pulmonary valve replacement (PVR) because of recellularization by host cells. The high frequency of graft failure gave reason to evaluate the underlying morphological substrate using magnetic resonance imaging (MRI) and histology.

METHODS

Between June 2006 and August 2008, 17 Matrix P® and 10 Matrix P plus® TEPVs were implanted in 26 patients with a median age of 12.4 (range: 0.8-38.7, interquartile range: 6.1-18.1) years. The grafts were studied by MRI, and underwent histological examination when explantation was required.

RESULTS

Surgical (n = 13) or transcatheter (n = 1) TEPV replacement because of graft failure was needed in 14 cases (52%) 19 (0.5-53) months after implantation. MRI detected significant TEPV stenosis with mild insufficiency (V(max) = 3.7 ± (standard deviation) 0.5 m/s, regurgitant fraction (RGF) = 10 ± 3%) and stenosis with moderate-to-severe insufficiency (V(max) = 3.5 ± 0.8 m/s, RGF = 38 ± 10%) in 6 patients, respectively, and severe insufficiency (RGF = 40%) in 1 patient. In patients with graft failure, MRI showed hyperenhancement and TEPV wall thickening. Histology revealed severe inflammation, increased fibrous tissue and foreign-body reaction against valve leaflets and fascial tissue, while TEPV endothelialization was not detected in any case.

CONCLUSIONS

The high frequency of Matrix P® and Matrix P plus® graft failure can be related to inflammation and fibrosis revealed by MRI and histology. Our results do not support the use of these valves for PVR and suggest careful follow-up examinations, including MRI for early detection of graft inflammation and fibrosis.

Fabrication and characterization of scaffold from cadaver goat-lung tissue for skin tissue engineering applications

The present study aims to fabricate scaffold from cadaver goat-lung tissue and evaluate it for skin tissue engineering applications. Decellularized goat-lung scaffold was fabricated by removing cells from cadaver goat-lung tissue enzymatically, to have cell-free 3D-architecture of natural extracellular matrix. DNA quantification assay and Hematoxylin and eosin staining confirmed the absence of cellular material in the decellularized lung-tissue. SEM analysis of decellularized scaffold shows the intrinsic porous structure of lung tissue with well-preserved pore-to-pore interconnectivity. FTIR analysis confirmed non-denaturation and well maintainance of collagenous protein structure of decellularized scaffold. MTT assay, SEM analysis and H&E staining of human skin-derived Mesenchymal Stem cell, seeded over the decellularized scaffold, confirms stem cell attachment, viability, biocompatibility and proliferation over the decellularized scaffold. Expression of Keratin18 gene, along with CD105, CD73 and CD44, by human skin-derived Mesenchymal Stem cells over decellularized scaffold signifies that the cells are viable, proliferating and migrating, and have maintained their critical cellular functions in the presence of scaffold. Thus, overall study proves the applicability of the goat-lung tissue derived decellularized scaffold for skin tissue engineering applications.

The Contegra conduit: Late outcomes in right ventricular outflow tract reconstruction

OBJECTIVES

To report the clinical outcomes (early death, late death, and rate of reintervention) and performance of the Contegra conduit as a right ventricle outflow tract implant and to determine the risk factors for early reintervention.

METHODS

Forty-nine Contegra conduits were implanted between January 2002 and June 2009. Data collection was retrospective. The mean age and follow-up duration of Contegra recipients was 3.5 ± 4.6 years and 4.2 ± 2.0 years, respectively.

RESULTS

There were three deaths (two early, one late), giving a survival rate of 93.9%. The rate of conduit-related reintervention was 19.6% and was most often due to distal conduit stenosis. Age at implantation of <3 months, receipt of a conduit of 12-16 mm diameter, and a diagnosis of truncus arteriosus were each significant contributors to the rate of reintervention.

CONCLUSION

The Contegra is a cost-effective and readily available solution. However, there is a limited range of larger calibers, which means that the homograft conduit (>22 mm) remains the first choice of implant in older children. The rates of reintervention are significantly higher with a diagnosis of truncus arteriosus, age at implantation of <3 months, and implantation of conduits sized 12-16 mm.

Early obstruction of decellularized xenogenic valves in pediatric patients: involvement of inflammatory and fibroproliferative processes

BACKGROUND

Decellularization of pulmonary valve substitutes is believed to eliminate immunogenicity and improve conduit durability. This study focused on a detailed histopathological and immunohistochemical analysis of explanted Matrix P plus valves, following their early obstruction in pediatric patients.

METHODS

Occurrence of fibrosis, scar formation, neovascularization, and inflammatory infiltrates were determined in longitudinal sections of four valve specimens explanted after 12-15 months. Valves were immunohistochemically analyzed for presence of different subtypes of inflammatory cells. The expression of smooth muscle actin and connective tissue growth factor was determined.

RESULTS

We observed a foreign body-type reaction accompanied by severe fibrosis and massive neointima formation around decellularized porcine valve wall, whereas the equine pericardial patch remained separated from porcine layer and acellular. Re-cellularization of decellularized matrix was low, and neovascularization was observed only in the neointima and scar tissue. Inflammatory infiltrates, composed mainly of T cells, B cells, and plasma cells, as well as the presence of dendritic cells, macrophages, and mast cells were detected in the tissue surrounding the porcine matrix. In the fibrous tissue, overexpression of connective tissue growth factor was observed. The leaflets remained functional, with normal endothelialization and no degenerative changes. Control pre-implant samples of Matrix P plus valve revealed incomplete decellularization of porcine matrix, which may have contributed to increased immunogenicity of these conduits.

CONCLUSIONS

Early obstruction of decellularized Matrix P plus valve is associated with massive inflammatory reaction and exaggerated fibrotic scaring around porcine conduit wall. Detailed studies will be necessary to determine factors that contribute to remnant immunogenicity of decellularized grafts.

Pulmonary valve implantation with the new Shelhigh Injectable Stented Pulmonic Valve

BACKGROUND

Pulmonary regurgitation (PR) occurs frequently after tetralogy of Fallot (TOF) repair, impairing long-term prognosis and necessitating reinterventions. Myocardial damage, invasiveness, and the risks of pulmonary valve replacement (PVR) therefore need to be minimized. The new Shelhigh Injectable Stented Pulmonic Valve (Shelhigh Inc, Union, NJ) allows implantation without cardiopulmonary bypass (CPB) under direct control.

METHODS

Twelve symptomatic patients (age, 21.3 +/- 12.5; range, 5.8 to 53.5 years) with severe PR and progressive right ventricular (RV) dilatation with dysfunction received the Shelhigh valve in sizes 21 (n = 1), 25 (n = 4), 27 (n = 3), 29 (n = 2), and 31 mm (n = 2).

RESULTS

Valve insertion was successful and hemodynamic performance excellent in all: peak systolic gradient, 14.5 +/- 4.6 (range, 10 to 20) mm Hg; mean gradient, 6.3 +/- 1.6 (range, 4 to 8) mm Hg. Four patients underwent concomitant procedures on CPB: one reduction plasty of a dilated main pulmonary artery, two tricuspid valve repairs, and one VSD closure. Early recovery was uneventful. There were no reoperations. During a mean follow-up of 5.4 +/- 4.3 months (range, 0.3 to 10.6 months) echocardiography showed good results, with low gradients and recovered RV function in all. All presented in New York Heart Association functional class 1 at the latest follow-up.

CONCLUSIONS

The Shelhigh valve allows easy PVR without CPB up to large valve sizes, with less invasiveness compared with a conventional approach. Further follow-up is needed to assess its durability and long-term performance.

MRSA endocarditis of bovine Contegra valved conduit: a case report

BACKGROUND

Different techniques are used for the right ventricular outflow tract reconstruction, including homo- or porcine xenografts, which have several limitations. Contegra, a bovine jugular vein graft, is an interesting alternative to overcome these limitations. It consists of a bovine jugular vein with a naturally integrated valve in it. Isolated pulmonary valve endocarditis is extremely rare.

CASE PRESENTATION

We report the case of a 20 years old male patient with acute endocarditis of bovine Contegra valved conduit, four years after right ventricular outflow tract reconstruction and atrial septal defect correction, associated with acute glomerulonephritis, renal failure and severe anemia, secondary to methicillin-resistant Staphylococcus aureus infection (MRSA).

CONCLUSION

We present a complex patient with acute endocarditis of bovine Contegra valved conduit. We believe that the presentation of this case should encourage the researchers for the discussing of the implantation of this conduit and the prevention of endocarditis in these patients.

True aneurysmal dilatation of a contegra conduit after right ventricular outflow tract reconstruction: a novel mechanism of conduit failure

Valved conduits are frequently used in congenital heart surgery to establish continuity between the right ventricle and the pulmonary arteries. The Contegra bovine jugular vein (Medtronic Inc, Minneapolis, MN) is a conduit that incorporates a tri-leaflet valve and affords off-the-shelf availability, good handling characteristics, and excellent hemodynamics. However, complications related to the use of this device have been reported, with conduit failure occurring mainly as a consequence of stenosis, conduit thrombosis, and valve regurgitation. We present a case of aneurysmal conduit failure of a 14-mm Contegra conduit used to reconstruct the right ventricular outflow tract.

Decellularized and photooxidatively crosslinked bovine jugular veins as potential tissue engineering scaffolds

Decellularization means and altering crosslinking approaches were two promising alternatives for glutaraldehyde fixation to biological tissues. Bovine jugular veins (BJVs) were decellularized by a multi-step detergent-enzymatic extraction method, then photooxidatively crosslinked. Gross and histological integrity of which was retained. Ultrastructures showed integrity of collagen fibrils and elastic fibers, and a basement membrane free luminal surface. Mechanical strength test and tissue protein extraction assay demonstrated their tissue stability. After being pre-coated with gelatin, collagen IV and fibronectin, cultured human umbilical vein endothelial cells were planted in the luminal surface of decellularized plus photooxidized BJV patches for seven days. Endothelial cells were denser in pre-coated patches than in uncoated controls. A rat subcutaneous implantation model revealed more resistance against in vivo degradation for further crosslinked BJV patches than decellularized patches at 12-week retrieval. Host cells were all layer repopulated for both. Histological examination and content assay demonstrated collagen and glycosaminoglycan components synthesis for decellularized plus photooxidized BJV patches. Decellularized and photooxidatively crosslinked BJV patches possess tissue integrity, excellent in vitro and in vivo tissue stability and repopulation patterns. Thus, they have potentials as tissue engineering scaffolds in future cardiovascular surgery.

Contegra conduit for reconstruction of the right ventricular outflow tract: a review of published early and mid-time results

Objective

The valved conduit Contegra (bovine jugular vein) has being implanted for more than 7 years in the right ventricular outflow tract and it is noted that the available reports have been mixed. The aim of this study is to review the reported evidence in the literature.

Methods

Search of the relevant literature for the primary endpoints of operative mortality and morbidity and secondary endpoints of follow-up haemodynamic performance including severe stenosis, regurgitation and need for reintervention are presented.

Results

We selected and analysed 17 series including 767 patients. Commonest indication was Fallot's tetralogy. Operative mortality was 2.6%. Operative morbidity was 13.9%. In follow-up, the incidence of intraconduit stenosis was 10.9% (incidence of stenosis for the 12 millimetre conduit was 83.3% in one series) and that of at least moderate regurgitation was 6.3%.

The aspirin users had a stenosis incidence of 10.5% compared to the non-users had a stenosis incidence of 9.6%.

Conclusion

A dissent on the performance of the Contegra is discussed, while results are satisfactory in the majority of studies apart for the smallest conduits (12 and 14 millimetre), suggesting an association to compromised run-off. The role of aspirin as antithrombotic modulator remains controversial.

Determinants of right ventricular outflow tract conduit longevity: a multinational analysis

OBJECTIVE

The need for conduit replacement in the growing child remains a major problem after right ventricular outflow tract reconstruction. We compared two diverse surgical centers with considerable practice variation in Europe and the United States to identify modifiable risk factors that can increase conduit longevity.

DESIGN

Retrospective analysis of 194 patients (56 Europe, 138 United States) who underwent primary right ventricular to pulmonary artery conduit placement between January 1987 and March 2003.

PATIENTS

Diagnoses included tetralogy of Fallot with pulmonary atresia, truncus arteriosus, transposition of the great arteries with ventricular septal defect and pulmonary stenosis, and double-outlet right ventricle.

RESULTS

Median age was 7.3 months (range 2 days-29.9 years). Types of conduits included aortic homografts (n = 111), pulmonary homografts (n = 48), Contegra conduits (Medtronic, Inc, Minneapolis, MN) (n = 23), and synthetic conduits (n = 12). Freedom from conduit failure at 5 years was 50% (58% Europe, 48% United States, P = NS). On multivariate analysis, smaller conduit diameter (hazard ratio [HR] 1.15, P < .001) and conduits other than pulmonary homografts (synthetic conduits [HR 3.17, P = .01], Contegra conduits [HR 2.80, P = .02], aortic homografts [HR 1.56, P = .05]) predicted shorter time to conduit failure. In addition, time to failure was longer for patients undergoing transcatheter intervention. Different surgical techniques in conduit preparation and insertion did not influence conduit longevity.

CONCLUSIONS

Analysis of the two diverse surgical centers showed that to increase conduit longevity, one should choose the largest possible conduit, use a pulmonary homograft, and consider children whose conduits develop obstruction as candidates for transcatheter intervention.

Early results of balloon dilatation of the stenotic bovine jugular vein graft in the right ventricular outflow tract in children

The aim of this study was to evaluate the early results of interventional balloon dilatation of stenotic bovine jugular vein (BJV) grafts implanted for reconstruction of the right ventricular outflow tract (RVOT) in children.

METHODS

From May 2001 to December 2005, 153 BJV grafts were implanted in children in our institution. An average of 16.9 (7.6-41.1) months after implantation, 17 balloon dilatations in a significant stenosis proximal (n = 1), distal anastomosis (n = 8), BJV valve (n = 3), or at multiple sites (n = 5) were performed in 15 children (male:female = 9:6) with a mean age of 3.9 (0.8-13.0) years. Balloon diameter was 75-133.3% (mean 100.3) of the original BJV size. Mean follow-up was 8.8 (2 days to 22.8 months) months.

RESULTS

In 10 interventions (58.8%) the instantaneous peak gradient was reduced below 50 mmHg. A balloon diameter > or =100% of the original BJV size correlated significantly with a successful intervention. No major complications, two minor (nonobstructive floating membranes at the dilatation site and one septicemia) occurred afterward. Freedom from reintervention after 6 months was 58.2% for all, 77.8% for dilatations of the proximal anastomosis and mixed stenotic lesions, and 33.3% for the distal anastomosis.

CONCLUSION

Balloon dilatation of stenotic BJV grafts is safe and can significantly reduce the pressure gradient in two-thirds of interventions. Balloon diameters above the original graft size should be aimed for. The most frequent stenosis of the distal anastomosis tends to renarrow early after dilatation. Nevertheless, balloon dilatation should be considered in nearly every stenotic graft to gain time until a surgical or interventional graft exchange.

Superior vena cava reconstruction using bovine jugular vein conduit

The glutaraldehyde-treated bovine jugular vein conduit (BJVC) is a xenograft conduit initially used for right ventricular outflow tract reconstruction and has never been used for reconstruction of superior vena cava (SVC). In September 2003, a patient with SVC obstruction underwent SVC reconstruction using BJVC. He has been alive for 42 months and free from signs and symptoms of SVC obstruction except that metastasis was found in the vertebrae. The radionuclide venography showed the graft tube was patent and only slight stenosis was found in the proximal anastomosis. The initial result supports BJVC as an acceptable alternative for SVC reconstruction.

Right Ventricular Outflow Tract Reconstruction With the Bovine Jugular Vein Graft: 5 Years’ Experience With 133 Patients

BACKGROUND

We analyzed the results in two centers of using bovine jugular vein graft for right ventricular outflow tract reconstruction.

METHODS

From April 1999 to July 2005, 133 children with a median age of 30.9 months (range, 4 days to 19 years) underwent graft implantation. Echocardiography was performed during follow-up and retrospectively reviewed.

RESULTS

Nongraft-related early mortality occurred in 8 patients. Late mortality occurred in 11 patients, 2 late deaths were graft related (endocarditis). Median follow-up was 31.6 months (range, 1 to 73). Twelve patients received a new graft, because of endocarditis (3), distal pulmonary artery branch stenosis (4), graft obstruction caused by fibrosis (4), or thrombosis (1). Echocardiography Doppler studies showed good conduit function, with 92% of the patients having absent, trivial, or only mild valve regurgitation at last follow-up. A moderate degree of conduit stenosis due to external compression was observed in 2 patients. Twenty-five patients with otherwise intact conduits had hemodynamically significant distal stenosis. In most cases, the pulmonary branch stenosis was related to preoperative small pulmonary arteries and young age at operation. At 31.6 months, significant graft dilatation was observed in 4 grafts and was related to pulmonary artery branch obstruction or pulmonary hypertension. Calcification did not occur in 5 years time. Survival was 85.7%, freedom from conduit explantation was 91%, and freedom from intervention for pulmonary artery branch stenosis was 80% after 5 years.

CONCLUSIONS

The bovine jugular vein graft is a valuable right ventricular outflow tract conduit, but younger age and small pulmonary arteries increase the risk of distal conduit stenosis.

Aneurysmal Dilatation of the Contegra Bovine Jugular Vein Conduit After Reconstruction of the Right Ventricular Outflow Tract

An aneurysm of a 14-mm Contegra bovine conduit 5 years after a total repair of tetralogy of Fallot was confirmed by echocardiography, angiography, and magnetic resonance tomography. The conduit was replaced. Histologic examination of the explanted conduit revealed an acellular homogenous material with occasional elastic fibers, fragile, diffuse and complex collagenization throughout the conduit and mild foreign body reaction. Pannus formed over the top of all commissures and on the conduit wall, with extensive mineralization. Close follow-up is seen as mandatory for early detection of the bovine vein conduit aneurysm, particularly in patients in whom small-sized conduits are implanted.

Right Ventricular Outflow Tract Reconstruction With Contegra Monocuspid Transannular Patch in Tetralogy of Fallot

BACKGROUND

Pediatric diminutive right ventricular outflow tract (RVOT) reconstruction with homografts or porcine xenografts remains challenging because of limited availability, early degeneration, tissue ingrowth, and child growth. The objective of this study was to assess whether Contegra valved bovine conduit, implanted as monocuspid transannular patch, might be an interesting alternative to overcome these problems.

METHODS

We reconstructed the RVOT of 12 patients with tetralogy of Fallot, by the use of a Contegra conduit, tailored as a monocuspid valved transannular patch. The patients were 4 females and 8 males, with a mean age of 12.8 +/- 15.1 months and a mean weight of 7.2 +/- 1.9 kg. The mean pulmonary artery annulus size was 8.2 +/- 1.6 mm.

RESULTS

The Contegra tissue was suitable for suturing and for reconstruction of even severely hypoplasic RVOT. We did not observe any sign of conduit or valve degeneration during the follow-up of 28.1 +/- 17.1 months. There were no early or late deaths, and no device-related adverse events. A peak transvalvular gradient of 36.5 +/- 4.7 mm Hg was measured by echocardiography in 4 patients postoperatively, and it decreased during the follow-up to 20 +/- 7.6 mm Hg. Pulmonary valve incompetence was grade 3 in 2 patients and grade 4 in 2 patients.

CONCLUSIONS

The Contegra monocuspid transannular patch is widely applicable to RVOT reconstruction with satisfactory midterm results, particularly in patients with small pulmonary annulus. Its main advantage is to reduce the potential risk of supravalvular stenosis due to the narrowing at the distal suture line, as demonstrated when used as conduits, especially in the smaller sizes.

Bovine Jugular Vein Conduit for Right Ventricular Outflow Tract Reconstruction: Evaluation of Risk Factors for Mid-Term Outcome

BACKGROUND

The bovine jugular vein conduit (Contegra [Medtronic, Inc, Minneapolis, MN]) is one option for right ventricular outflow tract reconstruction. We examined the effect of patient age, conduit size, hemodynamics, and cardiac malformation on early and mid-term outcome.

METHODS

Seventy-eight bovine jugular vein implantations were performed over 5 years. Follow-up averaged 31 +/- 17 months. Risk factor and adverse event analyses for graft dysfunction were performed by multivariate logistic regression and Kaplan-Meier analysis.

RESULTS

There was no early mortality. Two late deaths occurred after 9 and 15 months. Early postoperative echocardiography revealed bovine jugular vein regurgitation greater than 2+ in 10 patients, all of which had conduit dilatation, had received a 12-mm conduit, and had a right-ventricular-to-left ventricular pressure ratio greater than 0.6. Two additional patients had severe conduit incompetence develop at the 2-year follow-up. During follow-up, mean gradients increased from 15 to 23 mm Hg (p = 0.03) and stenosis at the distal anastomosis occurred in 25% of patients. Percutaneous interventions were performed in 19 patients (24.4%). Conduit exchange was required in 10 patients (12.8%) after a mean of 14.9 months for severe graft incompetence (8 patients) and progressive supravalvular stenosis (2 patients). Freedom from reoperation was 77.6% and 59.3% at 1 and 4 years for patients less than 1 year of age compared with 93.5% and 87.4% for patients older than 1 year of age (p < 0.001). Risk factors for reoperation were age less than 1 year, correction of truncus arteriosus, conduit size of 12 mm, and persistently elevated right-ventricular-to-left ventricular pressure ratio greater than 0.6 (p = 0.001 each).

CONCLUSIONS

Bovine jugular vein implantation is associated with low reoperation and acceptable reintervention rate in patients older than 1 year of age. In infants with persistently elevated right ventricular pressure, reoperation rate was high and had to be compared with other established surgical options.

Encouraging results for the Contegra conduit in the problematic right ventricle–to–pulmonary artery connection

OBJECTIVE

The Contegra conduit was developed for right ventricular outflow tract reconstruction. This report evaluates the Contegra conduit, with focus on certain subpopulations in which conduits are known to perform poorly (ie, patients with previous homograft conduits and infants).

METHODS

A retrospective review of 76 patients who had 77 Contegra conduits placed for right ventricular outflow tract reconstruction (January 2001 through August 2005) was completed. Characteristics include the following: median age of 1.6 years (range, 17 days-15.1 years), weight of 9.8 kg (range, 2.5-64.0 kg), and conduit diameter of 16 mm (range, 12-22 mm). Operations performed include right ventricular outflow tract reconstruction for pulmonary atresia-stenosis (n = 33), conduit exchange (n = 28), truncus repair (n = 7), primary conduit placement (n = 6), and the Ross procedure (n = 3). Seventy-nine percent were reoperations.

RESULTS

There was no hospital mortality. Mean follow-up was 20 +/- 14 months. One-, 2-, and 3- year freedom from severe conduit regurgitation was 97%, 86%, and 81%, respectively, and freedom from severe conduit stenosis was 100%. Freedom from reoperation for conduit failure at 1 and 3 years is 98.3% and 93.1%, respectively. All conduit failures (n = 3) were for asymptomatic conduit pseudoaneurysms in the setting of multiple-level pulmonary branch stenoses. Survival at 3 years is 96%. Infants (n = 26) had a freedom from Contegra conduit failure at 3 years of 100%. Patients with previous homograft conduits (n = 26) had a freedom from Contegra conduit failure at 3 years of 100%.

CONCLUSION

At midterm follow-up, the Contegra conduit remains a reliable, accessible, and easily implantable conduit for right ventricular outflow tract reconstruction. It appears to be the most promising conduit option for patients with previous homograft conduits and for infants.

Early Graft Failure of Small-Sized Porcine-Valved Conduits in Reconstruction of the Right Ventricular Outflow Tract

BACKGROUND

The quest for an alternative to homografts for reconstruction of the right ventricular outflow tract is ongoing. The Shelhigh No-React (NR-4000PA series) treated porcine pulmonic valve conduit (SPVC) was developed as a potential alternative.

METHODS

During a 12-month period from May 2004 to May 2005, the SPVC was implanted in 34 patients, of whom 62% were younger than 1 year. Median age at operation was 7 months (range, 5 days to 12 years). Thirteen SPCV conduits size 10, 11 size 12, 8 size 14, and 2 size 16 were initially implanted. Since May 2005, however, we have temporarily abandoned its implantation as we were concerned about a number of early failures.

RESULTS

Until November 2005, 1 early and 1 late death have occurred. Both were not conduit related. Fifteen conduits were replaced in 13 patients. Of these, 10 were size 10, 3 size 12, 2 size 14, and none size 16. Mean time to replacement of the SPVC was 313 +/- 116 days. A pseudointimal peel formation and chronic inflammation with foreign-body reaction was found in all explanted conduits at all levels. The maximum of the inflammatory reaction occurred at the valvular level around the porcine tissues, with shrinkage of the valve and hemodynamic compromise. At valvular level, small punctuate calcifications were observed in 2 cases. In 6 patients an acute inflammatory component was observed. At late follow-up (mean follow-up 366 +/- 102 days, 34 patient-years), echocardiography showed a mean graft gradient of 39.8 +/- 29.7 mm Hg, with mild to moderate insufficiency in 4 patients.

CONCLUSIONS

Although the No-React treated valve largely resists calcification, pseudointimal peel formation was found in all explanted conduits and led to multilevel conduit stenoses. The small-sized SPVC can not be regarded as an ideal conduit for right ventricular outflow tract reconstruction.