Early clinical outcomes of right ventricular outflow tract reconstruction with small caliber bovine jugular vein conduit (Contegra®) in small children

Current development of bovine jugular vein conduit for right ventricular outflow tract reconstruction

Right ventricular outflow tract (RVOT) reconstruction is a common surgical method to treat congenital cardiac lesions, and bovine jugular vein conduit (BJVC) has become a prevalent candidate of prosthetic material for this procedure since 1999. Although many clinical studies have shown encouraging results on BJVCs, complications such as stenosis, aneurysmal dilatation, valve insufficiency, and infective endocarditis revealed in other clinical outcomes still remain problematic. This review describes the underlying mechanisms causing respective complications, and summarizes the current technological development that may address those causative factors. Novel crosslinking agents, decellularization techniques, conduit coatings, and physical reinforcement materials have improved the performances of BJVCs. The authors expect that the breakthroughs in the clinical application of BJVC may come from new genetic research findings and advanced characterization apparatuses and bioreactors, and are optimistic that the BJVC will in the future provide sophisticated therapies for next-generation RVOT reconstruction.

Application of Homograft Valved Conduit in Cardiac Surgery

Valved conduits often correct the blood flow of congenital heart disease by connecting the right ventricle to the pulmonary artery (RV-PA). The homograft valved conduit was invented in the 1960s, but its wide application is limited due to the lack of effective sterilization and preservation methods. Modern cryopreservation prolongs the preservation time of homograft valved conduit, which makes it become the most important treatment at present, and is widely used in Ross and other operations. However, homograft valved conduit has limited biocompatibility and durability and lacks any additional growth capacity. Therefore, decellularized valved conduit has been proposed as an effective improved method, which can reduce immune response and calcification, and has potential growth ability. In addition, as a possible substitute, commercial xenograft valved conduit has certain advantages in clinical application, and tissue engineering artificial valved conduit needs to be further studied.

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 8 months 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 24 hours, 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.

Mid-term outcomes of Contegra implantation for the reconstruction of the right ventricular outflow tract to proximal branch pulmonary arteries: Japan multicentre study

OBJECTIVES

To reveal the mid-term outcomes of Contegra implantation for the reconstruction of the right ventricular outflow tract to proximal branch pulmonary arteries in a multicentre study.

METHODS

Between April 2013 and December 2019, 178 Contegra conduits were implanted at 5 Japanese institutes. The median age and body weight at operation were 16 months (25th-75th percentile: 8-32) and 8.3 kg (6.4-10.6). Sixteen patients were neonates (9.0%). Selected conduit sizes were 12 mm in 28 patients (15.7%), 14 mm in 67 patients (37.6%), 16 mm in 66 patients (37.1%), 18 mm in 5 patients (2.8%) and <12 mm in 12 patients (6.7%). Fifty-six grafts (31.4%) were ring supported. Proximal branch pulmonary arteries were concomitantly augmented in 85 patients (47.5%). Follow-up was completed in all patients and the median follow-up period was 3.1 years (1.3-5.1).

RESULTS

The overall, conduit explantation-free and conduit infection-free survival rates at 5 years were 91.3%, 71.0% and 83.7%, respectively. Infection (P = 0.009) and common arterial trunk (P = 0.024) were risk factors for explantation. Conduit durability was shorter in smaller one (P < 0.001). Catheter interventions (for conduit to proximal branch pulmonary artery)-free survival rates at 5 years was 52.9%; however, need for catheter interventions was not a risk factor for conduit explantation.

CONCLUSIONS

Mid-term outcomes of reconstruction of the right ventricular outflow tract to the proximal branch pulmonary arteries with Contegra were acceptable. The need for explantation over time was higher in smaller conduits. Conduit infection was a strong risk factor for conduit explantation. Frequently and repeated catheter interventions effectively extended the conduit durability.

Outcomes of Right Ventricular Outflow Tract Reconstruction in Children: Retrospective Comparison Between Bovine Jugular Vein and Expanded Polytetrafluoroethylene Conduits

Bovine jugular vein (BJV) and expanded polytetrafluoroethylene (ePTFE) conduits have been described as alternatives to the homograft for right ventricular outflow tract (RVOT) reconstruction. This study compared RVOT reconstructions using BJV and ePTFE conduits performed in a single institution. The valve functions and outcomes of patients aged < 18 years who underwent primary RVOT reconstruction with a BJV or ePTFE conduit between 2013 and 2017 were retrospectively investigated. 44 patients (20 and 24 with BJV and ePTFE conduits, respectively) met the inclusion criteria. The mean follow-up time was 4.5 ± 1.5 years. No significant differences in peak RVOT velocity (1.8 ± 0.9 m/s vs 2.1 ± 0.9 m/s, P = 0.27), branch pulmonary stenosis (P = 0.50), or pulmonary regurgitation (P = 0.44) were found between the BJV and ePTFE conduit groups, respectively. Aneurysmal dilatation of the conduit was observed in 25.0% of the patients in the BJV conduit group but not in the ePTFE conduit group (P = 0.011). All the cases with aneurysmal dilatation of the BJV conduit were complicated with branch pulmonary stenosis up to 3.0 m/s (P = 0.004). No conduit infections occurred during the follow-up period, and no significant difference in conduit replacement (20.0% vs 8.3%, P = 0.43) was found between the BJV and ePTFE conduit groups, respectively. The outcomes of the RVOT reconstructions with BJV and ePTFE conduits were clinically satisfactory. Aneurysmal dilatation was found in the BJV conduit cases, with branch pulmonary stenosis as the risk factor.