Pulmonary Valve Conduit Research Articles

Pediatric RVOT reconstruction with ePTFE trileaflet valved conduits: a dual-center Chinese study.

This study aims to assess the early to mid-term clinical efficacy of expanded polytetrafluoroethylene (ePTFE) trileaflet valved conduits in pediatric right ventricular outflow tract reconstruction for congenital heart disease. We conducted a retrospective analysis of pediatric patients who underwent right ventricular outflow tract (RVOT) reconstruction using ePTFE trileaflet valved conduits at two cardiac centers in China, between January 2017 and June 2023. The main assessment criterion was the functionality of the prosthetic pulmonary valve conduit. A total of 162 pediatric patients were included, with follow-up periods ranging from 0.1 to 5 years post-discharge, and a median follow-up duration of 1 year (interquartile range: 1, 2). Three patients (1.9%) required re-operation due to conduit obstruction. During follow-up, pulmonary valve flow velocities were recorded as <3 m/s in 134 patients (82.7%), between 3 and 4 m/s in 24 patients (14.8%), and >4 m/s in 4 patient (2.5%). Mild pulmonary valve regurgitation was noted in 148 patients (91.4%), and moderate pulmonary valve regurgitation was noted in 14 patients (8.6%), with no instances of more than moderate pulmonary valve regurgitation. The ePTFE trileaflet valved conduit, known for its accessibility and simplicity in manufacturing, demonstrates favorable early to mid-term clinical outcomes in pediatric RVOT reconstruction.

Application of right ventricular to pulmonary valved conduit in the surgical treatment of congenital heart disease.

Pulmonary valve replacement and right ventricular outflow tract reconstruction with valved conduits have been the shortcomings of paediatric cardiac surgeons in the treatment of CHD. In recent decades, encouraging achievements have been made in right ventricular outflow tract technology. Since Klinner reported the first right ventricle-to-pulmonary artery connection using unvalved conduits made of autologous pericardium in 1964, various right ventricle-to-pulmonary artery conduits have gradually been used in the treatment of various complex CHD. Compared with other materials, valved homograft conduit (VHC) is more consistent with physiological characteristics, better haemodynamics, easy suture and good haemostasis, anti-calcification, anti-infection, and without the need for lifelong anticoagulation, which makes VHC the best material for reconstruction of right ventricular outflow tract. However, due to the shortage of donor sources, other alternative conduits such as polytetrafuoroethylene valved conduits have been developed, and the results are not inferior to VHC in clinical application. The emerging tissue engineering technology is expected to utilise recipient-derived endothelial cells for implantation onto the decellularized VHC or degradable synthetic materials in order to construct a recipient-specific tissue-engineered valved conduit. This advancement holds great potential as an ideal biological transplant material and valve replacement for CHD. It will completely solve the problems of immune rejection and the growth of the conduit that cannot adapt to the physical growth of children. This review provides a comprehensive review of the clinical indications for right ventricle-to-pulmonary artery conduits application, optimal timing for surgery, current practices in utilising various types of external conduits, and considerations for re-replacement.

Valved Conduits for Right Ventricular Outflow Tract Reconstruction: A Review of Current Technologies and Future Directions.

The need for right ventricular outflow tract reconstruction is common and growing in congenital heart surgery given expanding indications for the repair of congenital as well as acquired heart disease. Various valved conduit options currently exist including homografts, xenograft pulmonary valved conduits (Contegra™), and porcine valved conduits. The major limitation for all conduits is implant durability, which requires reoperation. Currently, cryopreserved homografts are often used given their superiority shown in long-term data. Significant limitations remain in the cost and availability of the graft, particularly for smaller sizes. Contegra conduits are available in a variety of sizes. Nonetheless, the data regarding long-term durability are less robust and studies comparing durability with homografts have been conflicting. Additionally, there is concern for increased rates of late endocarditis in this conduit. Porcine valved conduits offer a reliable option but are limited by structural valve degeneration associated with all types of bioprosthetic heart valve replacements. New developments in the field of tissue engineering have produced promising bio-restorative valved conduits that may overcome many of the limitations of previous conduit technologies. These remain in the early stages of clinical testing. This review summarizes the clinical data surrounding the conduits used most commonly in clinical practice today and explores emerging technologies that may bring us closer to developing the ideal conduit.

Risk factors for coronary artery complications after prosthetic pulmonary valve implantation in congenital heart diseases

Abstract Background The incidence and risk factors for coronary artery complications in patients who underwent pulmonary valve replacement or valved conduit interposition for congenital heart diseases were unknown. Purpose This study was an extension of the previous study† to investigate the incidence and risk factors of coronary artery complications among patients who underwent prosthetic pulmonary valve implantation. Methods Retrospective cohort study was performed for the patients who underwent cardiac CT or invasive coronary angiography after the prosthetic pulmonary valve implantation at the tertiary referral hospital from June 1986 to May 2021. The rotation angle of the aorta and angles of both coronary artery orifices were measured on a Picture Archiving and Communication System (Figure 1). The Cox regression analysis was used to identify variables predicting the occurrence of coronary artery complications. Survival rates were assessed by Kaplan-Meier analysis. Results Coronary artery complications were identified in 25 patients among the 341 patients (7.3%), and two of them died. The median age at diagnosis of coronary artery complications was 20 years (interquartile range: 12.5-25 years). The coronary artery complication-free survival rate was predicted to be 97.3% at 5 years, 92.5% at 10 years, 85.5% at 20 years, and 61.1% at 30 years. The risk of cardiac death was 1.865 times higher [95% CI: 0.403, 8.628] in patients with coronary artery complications than in those without it; nevertheless, the difference was not statistically significant (p-value = 0.425). Among the patients with coronary artery complications, congenital coronary anomalies were identified in 11 (44 %), interarterial course of coronary artery in 18 (72 %), and intramural course in 4 patients (16%). Interarterial course and intramural course of the coronary artery were associated with a 4.4 and 10.6-fold increased risk of coronary artery complications, respectively. When subgroup analysis was performed in patients with tetralogy of Fallot and pulmonary atresia, the aortic root rotated more clockwise in patients with coronary artery compression than in patients without it (128.0°± 19.9° versus 113.5°± 23.7°, p-value = 0.024). The cut-off value of the rotation angle to predict the occurrence of coronary artery compression was 133˚ (Figure 2). Conclusion Preoperative and postoperative long-term coronary assessment should be performed in patients with conotruncal anomalies undergoing prosthetic pulmonary valve implantation, especially in those with abnormal courses of coronary arteries or severe rotation of aortic root. The rotation angle of aorta could be measured on cardiac CT angiography prior to surgery, and the location of the prosthetic valve or conduit should be carefully determined.Measurement of anglesKaplan-Meier curves

On-demand heart valve manufacturing using focused rotary jet spinning

On-demand heart valve manufacturing using focused rotary jet spinning

Prolonged Fever in a Child With Congenital Heart Disease and a Prosthetic Valve.

Prolonged Fever in a Child With Congenital Heart Disease and a Prosthetic Valve.

740 TREATMENT STRATEGY IN CASE OF REPAIRED TRUNCUS ARTERIOSUS AND AORTIC COARCTATION

Abstract Background Common Truncus arteriosus (TA) is a rare congenital, cyanotic heart disease with a single vessel coming out from both ventricles and related low interventricular defect, right-left shunt, low pulmonary flow and right ventricle (RV) hypertension. TA is associated with aortic coarctation (CoA) in 10-20% of cases. Case A 15-year-old male affected by type 2 TA and CoA undergoing first post-natal cardiac surgery with pulmonary valved conduit (PVC) implantation and CoA repair, subsequently multiple percutaneous (PC) interventions due to right pulmonary artery (RPA) stenosis and re-CoA. He was referred to our Centre for dyspnoea on mild efforts. Echocardiography revealed RV hypertension (75% of systemic pressure) and mild disfunction. Angio-CT showed RPA re-stenosis due to peeling of previous stents, a degenerative PVC and mild residual CoA. Results Cardiac catheterization confirmed imaging findings, revealing the following systolic/diastolic blood pressures [mmHg]: 100/15 in RV, 33/10 in left pulmonary artery (LPA), 13/7 in RPA, 132/65 in ascending and 125/60 in descending aorta. First, extensive balloon-interrogation of stented RPA and RV outflow tract (RVOT) with semi-compliant balloon was performed followed by PC intra-stenting transluminal angioplasty of RPA with modified undersized non-compliant balloon. As RPA was very closed to CoA with risk of aortic rupture, and mostly the main pulmonary OT accounted for increased pressure gradient, RPA enlargement with re-stenting was avoided. Then, a long semi-opened-cell stent was arranged on the prosthetic RVOT and Melody valve was implanted as Valve-in-Valve (ViV), both with balloon post-dilatation. Dilated LPA with only moderate focal stenosis and mild residual CoA were excluded from intervention. Post-interventional right heart pressures were reduced: 45/4 in RVOT and 42/13 mmHg in the main PA. At 1 month dyspnoea disappeared with good effort tolerance, echocardiographic ViV mean gradient was 12 mmHg with improved RV systolic function and pressure (50% of systemic). Conclusions Repaired complex TA of type described may develop multiple re-stenosis of RPA. RPA optimization was not the goal of the procedure because at high risk of vessels’ injury due to the very closed anatomy with otherwise prosthetic CoA. RV pressures and dysfunction could depend on degenerative obstructive PVC. Thus, interventional approach mostly focused on the main PA aimed at working PVC could be the best effective treatment.

Long-Term Follow-Up of Right Ventricle to Pulmonary Artery Biologic Valved Conduits Used in Pediatric Congenital Heart Surgery

Valved conduit reconstruction between the right ventricle (RV) and the pulmonary circulation is often necessary in the surgical treatment of complex congenital heart defects. The aim of this study is to evaluate the long-term performance of the three types of conduits we have used and assess risk factors for conduit failure. Retrospective, single-center review of 455 consecutive pediatric patients with 625 conduits from 1990 to 2019 undergoing RV-to-pulmonary artery (PA) reconstruction with a valved conduit. The three conduit types investigated were pulmonary homograft, aorta homograft, and bovine jugular vein (BJV) graft. Overall patient survival was 91.4%, freedom from conduit replacement (FCR) was 47.4%, and freedom from reintervention (FFR) was 37.8% with a median follow-up of 8.7 years (interquartile range 4.3–13.3 years). For pulmonary homografts, 10-, 20-, and 28-year FCR was 79.6%, 68.6%, and 66.0%, respectively. For aortic homografts, 10-, 20-, and 30-year FCR was 49.8%, 31.5%, and 23.0%, respectively. For BJV grafts, 10- and 19-year FCR was 68.1% and 46.0%, respectively. When controlling for baseline variables, FCR was similar for pulmonary homografts and BJV grafts. Overall patient survival was excellent. Risk factors for conduit failure in patients operated with reconstruction of the RV-PA outflow tract included low age, low weight, small conduit size, and certain cardiac diagnoses. There was no evidence for a shorter life span of the second graft. Pulmonary homografts and BJV grafts performed similarly but the risk of endocarditis was greater in the BJV group.

The Utility of Three-Dimensional Echocardiography in the Assessment of Pulmonary Valve Function in a Novel “Hand-Made” Pulmonary Valve Conduit

The right ventricle to pulmonary artery valved conduit is a key component of surgeries to rehabilitate the right ventricular outflow tract in children with congenital heart disease. Evaluation of the conduit valve function forms a key part of follow-up evaluation of these children. We report the utility of three-dimensional transthoracic echocardiography to evaluate the conduit valve function in these children.

Hand-sewn expanded polytetrafluoroethylene valved conduit for right ventricular outflow tract reconstruction.

Due to the lack of large-sized pulmonary valved conduit products in clinical practice, hand-sewn expanded polytetrafluoroethylene (ePTFE) valved conduit has been used for right ventricular outflow tract (RVOT) reconstruction in many heart centers around the world. This study aims to summarize the early results of the ePTFE valved conduit and the sewing technology of the conduit in combination with the latest progress, and to provide a reference for the application of ePTFE valved conduit. A total of 21 patients using ePTFE valved conduit for RVOT reconstruction in the Second Xiangya Hospital, Central South University from October 2018 to October 2020 were prospectively enrolled in this study. The age at the implantation of the conduit was 4.3 to 43.8 (median 15.1) years old, with weight of (38.9±4.1) kg. In this cohort, 14 patients underwent re-reconstruction of RVOT, including 12 patients with pulmonary regurgitation at 6.3 to 31.0 (median 13.8) years after tetralogy of Fallot (TOF) repair, and 2 patients with failed bovine jugular vein conduit (BJVC). Seven patients underwent Ross operations. Among them, 3 were for aortic valve stenosis, 2 were for aortic regurgitation, and 2 were for both stenosis and regurgitation. The ePTFE valved conduits were standard hand-sewn during the surgery. The 3 leaflets were equal in size with arc-shaped lower edge of the valve sinus. The free edge of the valve leaflets was straight with the length of about 1 mm longer than the diameter. The height of the valve sinus was 4/5 of the diameter. The junction of the valve leaflet was 3/4 of the height of the sinus. The designed leaflets were then continuous non-penetrating sutured into the inner surface of Gore-Tex vessel to make a valved conduit. Valved conduits with diameter of 18, 20, and 22 mm were used in 2, 9, and 10 cases, respectively. The surgical results, postoperative recovery time, and serious complications were summarized, and the changes of postoperative cardiac function status and hemodynamic status of the conduits were investigated. During the implantation of ePTFE valved conduit for RVOT reconstruction, 2 patients underwent mechanical mitral valve replacement with Ross operation, 2 patients with pulmonary regurgitation with repaired TOF underwent left and right pulmonary artery angioplasty, and 1 patient with failed BJVC underwent tricuspid valvuloplasty. The cardiopulmonary bypassing time for patients underwent re-reconstruction of RVOT was (130.9±16.9) min, with aorta clamping for 1 patient to repair the residual defect of the ventricular septum. The cardiopulmonary bypassing and aorta clamping time for Ross operation were (242.7±20.6) min and (145.6±10.5) min, respectively. The duration of postoperative ventilator assistance, intensive care unit stay, and hospital stay were 3.5 h to 7.7 d (median 17.1 h),11.2 h to 29.5 d (median 1.9 d), and 6.0 to 56.0 (median 13.0) d, respectively. All patients survived after discharge from hospital. The follow-up rate after discharge was 100% with median time at 15.0 (13.0 to 39.0) months. No death happened during the follow-up. One patient underwent stent implantation due to right coronary stenosis 2 months after Ross operation. One patient underwent balloon dilation due to right pulmonary artery ostium stenosis 1 year after re-reconstruction of RVOT. The cardiac function of all patients recovered to NYHA class I 6 months after operation. The peak pressure gradient across the valve measured by transthoracic echocardiography before discharge was (9.4±2.6) mmHg (1 mmHg=0.133 kPa), and (18.3±6.1) mmHg at the last follow-up. There was no significant increase in the gradient during the follow-up (P=0.134). No patient suffered from mild or more pulmonary regurgitation. Hand-sewn ePTFE valved conduit is feasible for RVOT reconstruction. It is a promising material for RVOT reconstruction which can effectively meet clinical need. In our experience, the ePTFE valved conduit is simple to manufacture with satisfactory early outcomes.In the application of ePTFE valved conduit, attention should be paid to implantation indications and postoperative anticoagulation management, especially to the preparation details of the valved conduit, to obtain better function and durability of the conduit after implantation.

Pulmonary Valve Designs and Innovation

Reconstruction of the right ventricular outflow tract and replacement of pulmonary valves in pediatric patients have been ongoing challenges, especially given the lack of a durable prosthesis that is adjustable to the patient’s growth needs and is free of infection risks. Preliminary Results With a Novel Expanded Polytetrafluoroethylene-based Pulmonary Valved ConduitThe Annals of Thoracic SurgeryVol. 114Issue 6PreviewA novel polymeric pulmonary valved conduit, resistant to calcification and structural valve deterioration, may provide a more durable therapy option for the pediatric population by preventing loss of right ventricular function and increasing freedom from valve-related reintervention and mortality. Full-Text PDF

Preliminary Results With a Novel Expanded Polytetrafluoroethylene-based Pulmonary Valved Conduit

BackgroundA novel polymeric pulmonary valved conduit, resistant to calcification and structural valve deterioration, may provide a more durable therapy option for the pediatric population by preventing loss of right ventricular function and increasing freedom from valve-related reintervention and mortality. MethodsThis was a prospective, multicenter, single-arm study evaluating safety and performance of an investigational novel expanded polytetrafluoroethylene–based valve. Patients met study inclusion/exclusion criteria, had a signed informed consent, had pre- and postoperative evaluation via transthoracic echocardiography, and 6-month cardiac magnetic resonance imaging. ResultsSeventeen patients were enrolled from 3 sites. Median age was 12 years (range, 6-17 years) with 52.9% male. Body surface area ranged from 0.82 to 1.57 m2. There has been no mortality and 100% freedom from device related reinterventions. Baseline compared with 6-month cardiac magnetic resonance imaging (in 11 of 16 patients with available data) suggests favorable right ventricular remodeling (right ventricular end-diastolic volume, 123 ± 37 to 94 ± 25 mL/m2) with no significant change in ejection fraction. Through current follow-up, no patient has a right ventricular outflow tract gradient >20 mm Hg (mean, 11.2 ± 4.3 mm Hg). No evidence of worsening valvular insufficiency was observed throughout postoperative serial transthoracic echocardiogram evaluations. No pulmonary regurgitation above baseline (≤ mild) was observed. No patient developed endocarditis. No thrombus or calcification was identified. ConclusionsThis preliminary evaluation of a novel expanded polytetrafluoroethylene–based valved conduit suggests promising valve function with no thromboembolic or infectious complications, no valve related reinterventions, no valve-related adverse events or unexpected findings, improved right ventricular volumes, and encouraging hemodynamic performance through current follow-up.

Neonatal or infantile palliation for Tetralogy of Fallot with or without pulmonary atresia: Modified Blalock–Taussig shunt versus restrictive right ventricle to pulmonary artery connection. A 20-year experience

To compare mortality, morbidity and efficiency of modified Blalock–Taussig shunt (mBTS) versus restrictive right ventricle to pulmonary artery connection (RVPAc) in patients with Tetralogy of Fallot (TOF) and TOF with pulmonary atresia (TOF-PA). We performed a monocentric retrospective review of 198 patients (93 TOF and 105 TOF-PA) who had palliation between 1996 to 2016 in their first year of life. Patients with Major aorto-pulmonary collaterals were excluded. Median follow-up was 11.0 [95% CI: 5.8–16.2] years after palliation. Five patients were lost at the follow-up. Ninety-five patients underwent mBTS, and 103 had an RVPAc. Nakata index before palliation was 129 (80–170) mm 2 /m 2 in mBTS group and 100 (71–146) mm 2 /m 2 in RVPAc group ( P = 0.001). Weight at palliation was similar between mBTS and RVPAc patients ( P = 0.1). Age at the palliation was 12 days (7–24.7) in RVPAc group and 21 days (8–87.5) in mBTS group ( P = 0.0002). One hundred and seventy-five patients underwent repair and 5 are waiting for it. Among them 39 necessitated a repair with a pulmonary valve conduit (23 mBTS and 16 RVPAc P = 0.004). Two patients were unsuitable for repair. Eleven patients died before repair (5.7%). There was no difference in mortality rate regarding the type of palliation ( P = 0.92) or the anatomical group ( P = 0.76). Interstage reintervention before repair was n = 37 (20%). Thirty-three were surgical and four were percutaneous. No difference in reintervention rate between RVPAc or mBTS regarding the age, the weight at palliation or the anatomical group ( P = 0.56). The delay between the palliation and the complete repair was shorter in RVPAc [12.3 (6.3–37.9) months versus 6.5 (4.9–10.3) months for mBTS ( P < 0.01)]. RVPAc provide a better and a faster pulmonary artery growth in our population. It led us to limit the use of RVPAc conduit at the repair. We found no significant difference between mBTS and RVPAc for mortality and interstage reintervention.

A decellularized porcine pulmonary valved conduit embedded with gelatin.

To prepare a tissue-engineered pulmonary valved conduit (PVC) with good tensile strength and biocompatibility. Sixty adult porcine PVCs were used to determine the optimal decellularization time. Five juvenile porcine decellularized PVCs and five juvenile porcine crosslinked PVCs were subsequently prepared according to the optimized decellularization and crosslinking methods. All PVCs were implanted into juvenile sheep for 8months and then were harvested for staining. With a low concentration of detergent (0.25% Triton X-100+0.25% sodium deoxycholate), the decellularization effect on porcine PVCs was complete by 24hours, and there was minimal damage to the matrix. Gelatin embedding and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) crosslinking improved the biomechanical properties of decellularized PVCs and reduced their immunogenicity. After implantation, the diameter and thickness of the PVCs in the decellularized and crosslinked groups increased significantly. In both groups, the conduits were unobstructed, with soft and smooth inner walls and without thrombosis, ulceration or neoplasia. The valves slightly degenerated with mild to moderate regurgitation. CD31-positive endothelial cells were visible on the inner surface of the conduits and valves. Scattered smooth muscle actin-positive cells were found in the middle layer of the conduit. The percentage of CD4- and CD68-positive cells and the calcium content were highest in decellularized porcine PVCs and lowest in ovine PVCs. The percentage of the matrix that was laminin-positive in decellularized and crosslinked porcine PVCs was lower than it was in ovine PVCs. Gelatin-embedded and EDC-crosslinked porcine PVCs can be "hosted" in sheep, with good biocompatibility, growth potential, and reduced calcification.

Better preoperative exercise function is associated with shorter hospital stay after paediatric pulmonary valve replacement or conduit revision.

Single centre retrospective cohort study of patients aged 8-18 years who underwent surgical pulmonary valve replacement. The primary predictor was preoperative percent predicted peak oxygen consumption, and primary outcome was total hospital length of stay. Clinical, imaging, and cardiopulmonary exercise test data were reviewed and compared to total hospital length of stay. Cox proportional hazards regression was used to examine the association between total hospital length of stay and percent predicted peak oxygen consumption. Three-hundred and seventy patients undergoing pulmonary valve replacement/conduit change between 2003 and 2017 at Boston Children's Hospital were identified. Ninety had preoperative cardiopulmonary exercise tests within 6 months of surgery. Exclusion for inadequate exercise data (n = 3) and imaging data (n = 1) left 86 patients for review. Patients with percent predicted peak oxygen consumption ≥ 70% (n = 46, 53%) had shorter total hospital length of stay (4.4 days) than the 40 with percent predicted peak oxygen consumption <70% (5.4 days, p = 0.007). Median percent predicted peak oxygen consumption increased over sequential surgical eras (p < 0.001), but total hospital length of stay did not correlate with surgical era, preoperative left ventricular function, or preoperative right ventricular dilation. Children undergoing surgical pulmonary valve replacement with better preoperative exercise capacity had shorter total hospital length of stay. Exercise capacity is a potentially modifiable factor prior to and after pulmonary valve replacement. Until more patients systematically undergo cardiopulmonary exercise tests, the full impact of optimisation of exercise capacity will not be known.

Screening for potential targets to reduce stenosis in bioprosthetic heart valves

Progressive stenosis is one of the main factors that limit the lifetime of bioprosthetic valved conduits. To improve long-term performance we aimed to identify targets that inhibit pannus formation on conduit walls. From 11 explanted, obstructed, RNAlater presevered pulmonary valved conduits, we dissected the thickened conduit wall and the thin leaflet to determine gene expression-profiles using ultra deep sequencing. Differential gene expression between pannus and leaflet provided the dataset that was screened for potential targets. Promising target candidates were immunohistologically stained to see protein abundance and the expressing cell type(s). While immunostainings for DDR2 and FGFR2 remained inconclusive, EGFR, ErbB4 and FLT4 were specifically expressed in a subset of tissue macrophages, a cell type known to regulate the initiation, maintenance, and resolution of tissue repair. Taken toghether, our data suggest EGFR, ErbB4 and FLT4 as potential target candidates to limit pannus formation in bioprosthestic replacement valves.

Abstract 14086: Early Results of a Novel EPTFE-based Pulmonary Valved Conduit in a Pediatric Patient Population

Introduction: This prospective, multicenter, single-arm, early feasibility study evaluates the safety and performance of an investigational ePTFE-based valve for replacement of the pulmonary valve and reconstruction of the Right Ventricular Outflow Tract. A novel polymeric pulmonary valved conduit, resistant to calcification and structural valve deterioration, may provide a more durable therapy option for the pediatric population by preventing loss of right ventricular function and increased freedom from valve-related reintervention and mortality. Methods: The primary endpoints at 6 months adjudicated by an independent Clinical Events Committee are valve-related mortality and device-related reintervention. The investigational device is a valved conduit comprised of ePTFE with stretch technology and a flexible tri-leaflet polymeric valve made of an advanced proprietary composite material, which can be tailored to length requirements of the anatomy. All enrolled patients met study inclusion/exclusion criteria and had a signed informed consent form. All patients had pre- and postoperative evaluation via transthoracic echocardiography (TTE). Aspirin was administered for a minimum of three months post procedure and, per institutional protocols, four patients were on temporary Coumadin. Results: Of the 17 patients enrolled from three sites, 52.9% were male. Ages ranged from 6 to 17 years (mean 11.5 ± 3.7). BSA ranged from 0.82 to 1.57 m 2 . At six months follow up, 100% of subjects successfully met the primary endpoint of freedom from valve-related mortality and device-related reintervention. No patient exhibited an RVOT gradient &gt; 20 mmHg. No patients had pulmonary regurgitation above baseline (≤ mild) observed through six months. Throughout postoperative serial TTE evaluation at discharge, 1, 3, and 6 months, no evidence of worsening valvular insufficiency was observed. No patient developed endocarditis and TTE detected no clinically significant thrombus formation. Conclusions: These preliminary data of a novel Pulmonary Valve Conduit suggest improved pulmonic and right ventricular function based on TTE measurements, no unexpected findings, no valve-related adverse events and encouraging hemodynamic performance through 6 months.

Unraveling the Mechanisms of Endogenous Tissue Restoration after Bioresorbable Pulmonary Valve Implantation in Sheep

Objective: Endogenous Tissue Restoration (ETR) utilizes the regenerative response of the human body to transform an off-the-shelf available, synthetic, absorbable graft into a living functional valve. Recent preclinical studies have shown the principle of ETR for heart valve grafts to be promising1Bennink G Torri S Brugmans M et al.A novel restorative pulmonary valved conduit in a chronic sheep model: Mid-term hemodynamic function and histologic assessment.J Thorac Cardiovasc Surg. 2018; 155 (doi:10.1016/j.jtcvs.2017.12.046.): 2591-2601Google Scholar,2Kluin J Talacua H Smits AIPM et al.In situ heart valve tissue engineering using a bioresorbable elastomeric implant – From material design to 12 months follow-up in sheep.Biomater. 2017; 125 (doi:10.1016/j.biomaterials.2017.02.007.): 101-117Google Scholar. However, further detailed knowledge on the underlying mechanisms of the material-driven regenerative response remains elusive. The goal of the present study was to gain a mechanistic understanding of these processes by histopathological analysis of ETR heart valves. Methods: In this study, Xeltis Pulmonary Valved Conduits (XPV, Xeltis B.V., Eindhoven, The Netherlands) implanted in an ovine model were analyzed. Explanted valves (follow-up time: 2, 6, 12 (N=5 per timepoint) and 24 months (N=2)) were embedded in paraffin and sectioned longitudinally. Spatiotemporal analysis was performed using a comprehensive sheep-specific antibody panel3Dekker S van Geeman D van den Bogaerdt AJ et al.Sheep-specific immunohistochemical panel for the evaluation of regenerative and inflammatory processes in tissue-engineered heart valves.Front. Cardiovasc. Med. 2018; 5 (doi:10.3389/fcvm.2018.00105.): 105Google Scholar. Results: Detailed knowledge on graft absorption as well as neo-tissue formation and a better understanding of cellular influences was obtained. Interestingly, foreign body giant cells were located within the graft material at iNOS-rich degradation and tissue remodeling sites in the hinge region of the leaflet, starting as early as 2 months after implantation. In the conduit material, on the other hand, foreign body giant cells remained on the outer layers with only limited infiltration into the scaffold material. Interestingly, at the same time point vascularization was observed throughout the conduit material. Extracellular matrix components, such as collagens and elastin were formed in a highly heterogeneous fashion, suggesting an important role for hemodynamic loads on the inflammatory and regenerative processes. Conclusions: Our results enhance the mechanistic understanding of material-driven endogenous tissue restoration. These findings also highlight, the importance of the micro-environment imposed by the graft material on the regenerative response towards a biomaterial. KEYWORD: ICTEHV-O-02 The authors do not declare any conflict of interest.

Percutaneous pulmonary valve implantation (PPVI) in non-obstructive right ventricular outflow tract: limitations and mid-term outcomes.

Percutaneous pulmonary valve implantation (PPVI) has been established as a safe and effective alternative to surgery treating patients with a failing pulmonary valve conduit. Nevertheless, the majority of patients in need of a valve have a native, non-obstructive right ventricular outflow tract (RVOT). The current approved stent-valves have a balloon-expandable design. Pre-stenting of the RVOT to create a landing zone and also protect the valve stability is usually mandatory; large, non-obstructive RVOTs need pre-stenting to reduce the RVOT-diameter for a balloon-expandable valve implantation. A retrospective study design was used to analyze the medium-term outcome after PPVI in a series of 26 patients with native or reconstructed RVOT. PPVI was successfully performed in all, but 1 (96%). Within the follow-up of a minimum of 2 years, the percutaneous implanted valves remained competent; a significant pressure gradient was not detected. Furthermore, no PPVI-related complications such as endocarditis, migration or stent fractures were observed. The electrocardiogram at rest, in particular the QRS duration remained unchanged immediate post-PPVI as well as at medium-term follow-up of 24 months. However, ventricular arrhythmias were documented in 3 patients (11.5%); all patients were successfully treated with antiarrhythmic drugs, utilizing metoprolol. A trial of an invasive catheter based RVOT-ablation in one remained unsuccessful; pre-stented RVOT did not allow a successful intervention. Medium-term follow-up showed excellent results of the mechanical valve function. PPVI utilizing balloon-expandable stent-valves in a native RVOT remains an off-label use. Despite our encouraging results, advanced manipulations of the patched or native RVOT might be associated with significant ventricular arrhythmias. There is a need for less invasive RVOT reduction devices.

Subclinical thrombus formation in bioprosthetic pulmonary valve conduits

ObjectivesBioprosthetic pulmonary valve conduits have been reported with an increased risk of endocarditis. Thrombus formation is considered as source of these serious and life-threatening infections. We reviewed a series of explanted valved pulmonary conduits for histological evidence for thrombus formation. Materials and methodsExplanted bioprosthetic pulmonary valves were fixed in formalin and embedded in paraffin or in methylmethacrylate. Standard staining as well as immunohistochemical staining techniques were applied. Native pulmonary valves of German domestic pigs served as controls. Results47 valved pulmonary conduits (Hancock n = 23, Homograft n = 7, Contegra n = 7, Melody n = 7, other n = 3) were analyzed histologically. Average time of implantation had been 63 months (6 to 342 months). Indications for explantation included significant obstruction (n = 45), regurgitation (n = 7), and/or endocarditis (n = 6). In 44/47 (93%) specimen, we found accumulation of thrombotic material at the basis of the semilunar valve sinus to a variable degree. 11 patients had been treated with antiplatelet agents, 2 had received anticoagulants at the time of explantation. There was no suspicion of thrombus formation clinically or echocardiographically prior to explantation in any of the patients.Control porcine pulmonary valves (n = 5) did not show any evidence of accumulation of thrombotic material. ConclusionsIn a large series of explanted valved pulmonary conduits, formation of subclinical, mostly non-infectious thrombotic material was an almost ubiquitous finding. We speculate that high incidence of endocarditis in bioprosthetic valves may in part be explained by thrombus apposition at the basis of conduit valve sinus.