Immobilized Bisphosphonates as Potential Inhibitors of Bioprosthetic Calcification: Effects on Various Xenogeneic Cardiovascular Tissues

Calcification is the major factor limiting the clinical use of bioprostheses. It may be prevented by the immobilization of bisphosphonic compounds (BPs) on the biomaterial. In this study, we assessed the accumulation and structure of calcium phosphate deposits in collagen-rich bovine pericardium (Pe) and elastin-rich porcine aortic wall (Ao) and bovine jugular vein wall (Ve) cross-linked with glutaraldehyde (GA) or diepoxy compound (DE). These tissues were then modified with pamidronic (PAM) acid or 2-(2′-carboxyethylamino)ethylidene-1,1-bisphosphonic (CEABA) acid. Tissue transformations were studied using Fourier-transform infrared spectroscopy. After subcutaneous implantation of the biomaterials in 220 rats, calcification dynamics were examined using atomic absorption spectrophotometry, light microscopy after von Kossa staining, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy The calcium content in all GA-cross-linked tissues and DE-cross-linked Ao increased to 100–160 mg/g on day 60 after implantation. BPs prevented the accumulation of phosphates on the surface of all materials and most effectively inhibited calcification in GA-cross-linked Ao and DE-cross-linked Pe. PAM containing -OH in the R1 group was more effective than CEABA containing -H in R1. The calcification-inhibitory effect of BPs may be realized through their ability to block nucleation and prevent the growth of hydroxyapatite crystals.

Midterm Outcomes of Crosslinked Acellular Bovine Jugular Vein Conduit for Right Ventricular Outflow Tract Reconstruction

Objectives: Conduits for reconstructing right ventricular outflow tract (RVOT) in children with congenital heart disease have evolved for better durability over the past decades, but conduits failure remains common. We designed decellularized and photooxidatively crosslinked bovine jugular vein conduit (DP-BJVC) and now aim to evaluate the midterm results of DP-BJVC for RVOT reconstruction.Methods: Ninety patients (median age: 4.2 years) undergoing RVOT reconstruction using DP-BJVC were prospectively followed for median of 4.7 years (range: 0.2–16.1 years). Kaplan–Meier analysis was used to examine the survival, freedom from conduit explantation and catheter-based reintervention. Risk factors were analyzed with Cox regression analysis.Results: Follow-up was completed in 92% of patients. There were five (5.6%) early deaths. The 10-year survival rate was 85.2%, with palliative procedure at DP-BJVC implantation as the risk factor. The 10-year freedom from conduit explantation and reintervention were 84.4 and 67.3% respectively, with previous cardiac operation as the only risk factor for explantation. Complications during the follow-up included conduit stenosis (peak gradient ≥50 mmHg) in 12 (12.9%), severe regurgitation in 2 (2.4%), and infective endocarditis in 2 (2.4%). The annual increase in gradient was highest in the first year (P = 0.003), but not appreciably afterwards. The echo-measured annulus diameter trends to increase by an average of 0.37 mm per year. Calcification appeared mild in the failed conduits.Conclusions: DP-BJVC provides satisfactory durability and functionality for RVOT reconstruction for children, with low morbidity of stenosis and endocarditis, as well as increase in diameter mildly with age in midterm follow-ups.

Bovine jugular vein conduit versus pulmonary homograft in the Ross operation

Objectives:The Ross procedure involves using the native pulmonary valve for aortic valve replacement then replacing the pulmonary valve with an allograft or xenograft. We aimed to compare our age-matched experience with the bovine jugular vein conduit and the pulmonary homograft for pulmonary valve replacement during the Ross procedure in children.Methods:Between 1998 and 2016, 15 patients <18 years of age underwent a Ross procedure using the bovine jugular vein conduit (Ross-Bovine Jugular Vein Conduit) at our institution. These patients were age-matched with 15 patients who had the Ross operation with a standard pulmonary homograft for right ventricular outflow tract reconstruction (Ross-Pulmonary Homograft). Paper and electronic medical records were retrospectively reviewed.Results:The median age of the Ross-Bovine Jugular Vein Conduit and Ross-Pulmonary Homograft patients were 4.8 years (interquartile range 1.1–6.6) and 3.3 years (interquartile 1.2–7.6), respectively (p = 0.6). The median follow-up time for the Ross-Bovine Jugular Vein Conduit and Ross-Pulmonary Homograft groups were 1.7 years (interquartile range 0.5–4.9) and 6.8 years (interquartile range 1.9–13.4), respectively (p = 0.03). Overall, 5-year survival, freedom from redo aortic valve replacement, and freedom from pulmonary valve replacement were similar between groups.Conclusion:The bovine jugular vein conduit and pulmonary homograft have favourable mid-term durability when used for right ventricular outflow tract reconstruction for the Ross operation. The bovine jugular vein conduit may be a suitable replacement for appropriately sized patients undergoing a Ross aortic valve replacement, though longer follow-up is needed.