Modification of the descending thoracic aortic anastomotic site using biodegradable felt: Study in a canine model with or without basic fibroblast growth factor
Received 26 September 2008; accepted 22 August 2009. published online 16 November 2009.
Objectives
We investigated the outcomes of reinforcing anastomotic sites using (1) nonbiodegradable polytetrafluoroethylene (PTFE) felt, (2) biodegradable polyglycolic acid (PGA) felt, and (3) PGA felt with basic fibroblast growth factor (bFGF) in a canine descending thoracic aortic replacement model.
Methods
Thirty-seven beagles underwent descending thoracic aorta replacement using a prosthetic graft with one of the above-mentioned reinforcements or no reinforcement for controls. Histologic evaluations were carried out 1 month and 3 months after surgery. The biomechanical strength of the anastomosis was assessed along the longitudinal axis of the aortic segments using a tensile tester. Local compliance at the anastomotic site was also evaluated in the circumferential direction.
Results
The media was significantly thinner in the PTFE group than in the control group (65.8% ± 5.1% vs 95.0% ± 9.3% of normal thickness; P < .05). Relative to the control group, the adventitial layer was significantly thinner in the PTFE group (42.3% ± 8.2% of control; P < .05) but significantly thicker in the PGA and the PGA + bFGF groups (117.2% ± 11.3% and 134.1% ± 14.2% of control, respectively; P < .05). There were more vessels in the adventitial layer in the PGA + bFGF group than in the control, PTFE, and PGA groups (29.2 ± 2.1/mm2 vs 13.8 ± 0.8, 5.4 ± 0.7, 17.0 ± 1.3/mm2, respectively; P < .01). There were no significant differences between the four groups in the failure force at anastomotic sites. Local compliance at the anastomotic site was higher in the PGA group than that in the PTFE group (11.6 ± 1.6 10−6 m2/N vs 5.6 ± 1.9 10−6 m2/N; P < .05).
Conclusion
Reinforcement of the experimental aortic wall with PTFE felt resulted in thinning of the media and adventitia and fewer vessels at the anastomotic site. These histologic changes were not observed when biodegradable felt was used. The bFGF failed to augment the modification of the aortic wall with the exception of increased adventitial vessel number. Biomechanical strength of the anastomosis along the longitudinal axis was comparable in all four groups; however, local vascular compliance was better in the biodegradable PGA felt group.
Clinical Relevance
This investigation was conducted to extend our previous investigation on a biodegradable felt strip into more practical form before we proceed in a clinical application of the new material. We hypothesized that sustaining compression of the aorta by the nonbiodegradable felt strip may cause structural derangement and local ischemia on the aortic wall, which may lead to occurrence of late postoperative false aneurysm after aortic surgery. We attempted to find a clue for preventing adverse effects of reinforcement with a conventional felt strip. We have found that biodegradable felt prevented thinning of both the media and adventitia and increased adventitial vessels with increased vascular compliance at the aortic anastomotic sites.
aDepartment of Cardiovascular Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan
bGraduate School of Mechanical Engineering, Tohoku University, Sendai, Japan
cInstitute for Frontier Medical Science, Kyoto, Japan
Reprint requests: Yoshikatsu Saiki, MD, Department of Cardiovascular Surgery, Graduate School of Medicine, Tohoku University, 1-1 Seiryomachi, Aoba-ku, Sendai, 980-8574 Japan
Competition of interest: none.
Drs Hidenori Fujiwara and Yoshikatsu Saiki contributed equally to this manuscript.
The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a competition of interest.
ABSTRACT