Influence of Tissue Technology on Pannus Formation on Bioprosthetic Heart Valves.

PURPOSE: Bioprosthetic heart valves have several modes of failure. Tissue degeneration and calcification are the major modes of failure with the highest focus of attention, however pannus formation can also be problematic. We studied the effect of a new tissue technology with the absence of any glutaraldehyde-based storage solution and a stable aldehyde capping process on pannus formation. METHODS: Using a juvenile sheep model of mitral valve replacement, valves with the new tissue technology were compared to control valves with contemporary bovine pericardial tissue, regarding pannus formation. Valves were implanted for either a 5- or 8-month period. Explanted valves were examined macroscopically and histologically. Histological observations were made by an independent pathologist, blinded to group identity. RESULTS: Pannus area measured macroscopically on the test valves was significantly lower than the pannus on the control tissue. This was confirmed on the histological samples, where the total pannus overgrowth was significantly lower in the test group compared to the control. CONCLUSION: The new tissue technology leads to less pannus formation. This may beneficially influence both short- and long-term valve behavior of bioprosthetic valves.

Aldehyde reduction in a novel pericardial tissue reduces calcification using rabbit intramuscular model.

Calcification is a major factor that limits the durability of bioprosthetic valve. A novel bovine pericardial tissue treated with aldehyde capping chemistry and glycerolization was evaluated for its resistance to calcification in comparison with porcine tissues treated with amino oleic acid and bovine pericardial tissue with ethanol rinsing in a rabbit intramuscular model. Tissue discs from the test and control tissues were implanted in rabbits for 60 days. The explanted discs were subject to X-ray imaging, calcium quantification and histology analysis. The test tissue showed 95 and 96 % reduction in calcification in comparison with amino oleic acid treatment and ethanol rinsing treatment, respectively. In addition, the test tissue showed the least inflammatory response as evidenced by a reduced amount of macrophages and giant cells in histology analysis. Furthermore, the aldehyde analysis of the pre-implanted samples showed associated reduction in free aldehyde levels with the test tissue. The reduction in calcification is consistent with previously reported results and is hypothesized to be attributed to the capping of free aldehydes in the test tissue.

Advanced Integrity Preservation Technology Reduces Bioprosthesis Calcification While Preserving Performance and Safety.

BACKGROUND AND AIM OF THE STUDY: Structural valve deterioration (SVD) is the leading failure mode of bioprosthetic heart valves. The Edwards Integrity-Preservation (EIP™) technology was developed to permanently block tissue calcium-binding sites and allow for non-aqueous valve storage. The study aim was to evaluate the efficacy of tissue anti-calcification, valve performance, durability, and safety. METHODS: Bovine pericardial tissue with EIP technology was compared to industry-standard Carpentier-Edwards ThermaFix® and Xenologix® treatments. Anti-calcification efficacy was evaluated in the rabbit model at 60 days, and tissue calcium contents were quantified using atomic absorption spectrophotometry. Valve performance was assessed using an in-vivo 20-week chronic ovine model, and in-vitro hydrodynamic testing (effective orifice area and regurgitation). Valve durability was evaluated by accelerated wear testing at 200 million cycles (equivalent to five years). Valve safety was characterized by biocompatibility testing as per ISO requirements. RESULTS: Calcification results showed that the control and EIP technology tissues had a mean Ca content of 104.95 ± 102.69 and 21.20 ± 38.46 µg/mg dry tissue, respectively; the median Ca contents were 81.15 and 0.43 µg/mg dry tissue, respectively (p < 0.0001). The overall valve performance in the sheep was comparable between control and test. In-vitro hydrodynamics and durability were similar between groups, across all sizes, and met ISO requirements. EIP technology was shown to be biocompatible for use as an implantable device. CONCLUSION: Preclinical in-vitro and in-vivo evaluations showed that EIP technology significantly reduced tissue calcification and preserved valve performance and safety compared to current standards of care. Future studies will determine whether these findings can be replicated in humans.

Assessing anticalcification treatments in bioprosthetic tissue by using the New Zealand rabbit intramuscular model.

The objective of this work was to demonstrate that the New Zealand White (NZW) rabbit intramuscular model can be used for detecting calcification in bioprosthetic tissue and to compare the calcification in the rabbit to that of native human valves. The rabbit model was compared with the commonly used Sprague-Dawley rat subcutaneous model. Eighteen rabbits and 18 rats were used to assess calcification in bioprosthetic tissue over time (7, 14, 30, and 90 d). The explanted rabbit and rat tissue discs were measured for calcium by using atomic absorption and Raman spectroscopy. Calcium deposits on the human valve explants were assessed by using Raman spectroscopy. The results showed that the NZW rabbit model is robust for detecting calcification in a shorter duration (14 d), with less infection complications, more space to implant tissue groups (thereby reducing animal use numbers), and a more metabolically and mechanically dynamic environment than the rat subcutaneous model . The human explanted valves and rabbit explanted tissue both showed Raman peaks at 960 cm(-1) which is representative of hydroxyapatite. Hydroxyapatite is the final calcium and phosphate species in the calcification of bioprosthetic heart valves and rabbit intramuscular implants. The NZW rabbit intramuscular model is an effective model for assessing calcification in bioprosthetic tissue.

Loose Body in Elbow of a Baseball Player: Arthroscopic/Radiologic Correlation.

We present the case of a 21 year old male college varsity baseball player who presented with sudden non-traumatic right elbow pain and limited range of motion. Plain radiographs suggested a calcified intra-articular body. Magnetic Resonance (MR) was performed to better characterize the location, consistency and mobility of this body. Multiple intra-articular bodies were found at subsequent arthroscopy. This case emphasizes the close correlation among the clinical, radiographic, MR and arthroscopic findings.