The wrapping method using biodegradable felt strips has a preventive effect on the thinning of the aortic wall: Experimental study in the canine aorta

Objectives: Wrapping methods have been widely used to reinforce the anastomotic site in vascular surgery; however, postoperative changes in the aortic wall wrapped by nonbiodegradable felt have not been well characterized. The purposes of this investigation are to elucidate the sequelae of wrapping with nonbiodegradable felt on the aortic wall and to modify those changes by using biodegradable felt with or without basic fibroblast growth factor (bFGF). Methods: The descending thoracic aortas of 15 beagles were wrapped with three different materials: nonbiodegradable polytetrafluoroethylene (PTFE) felt, biodegradable polyglycol acid (PGA) material, and PGA with 100 μg bFGF (n = 5 in each group). The descending thoracic aorta was resected after 3 months. The thickness of the aortic wall, vessel density in the media and the adventitia, and the wall strength were assessed. Untreated native aortic wall served as a normal control. Results: The thickness of the media of the PTFE group was lower than that of the PGA + bFGF group (66% ± 5% vs 85% ± 6% of control, P < .05). The adventitia-media ratio in the PTFE group decreased compared with controls (59.1% of normal, P < 0.05), whereas those in the PGA and PGA + bFGF groups increased (172.1% and 189.6% of normal, respectively, P < .01). The collagen-smooth muscle ratio in the media was higher in the PTFE group than in the controls (0.14 ± 0.02 vs 0.07 ± 0.01, P < .01). The number of vessels in the adventitia was higher in the PGA + bFGF group than those in PTFE or PGA groups (29.6 ± 2.5/mm ² vs 6.4 ± 0.8/mm ², 19.0 ± 1.1/mm ², P < .01). The PGA + bFGF group demonstrated larger failure force than the PTFE group (4.0 ± 0.3 kgf vs 1.6 ± 0.3 kgf, P < .01). The failure stress in the PGA and PGA + bFGF groups was larger than that in PTFE group (PTFE:PGA + bFGF = 5.3 ± 0.9 ×10 ² kPa:11.7 ± 1.7 × 10 ² kPa, P < .01; PTFE:PGA = 5.3 ± 0.9 × 10 ² kPa:11.2 ± 1.2 × 10 ² kPa, P < .05). Conclusion: The aortic wall wrapped with nonbiodegradable PTFE felt showed a reduced thickness and diminished vessels in the adventitia. Biodegradable felt (PGA), with or without bFGF, modified these histologic changes. The vessel-rich thickened adventitia, after wrapping by PGA with bFGF, was associated with increased aortic wall strength.