Vessel Remodeling after Intima-to-Intima Contact Anastomosis

Background Intima-to-intima microanastomotic vascular remodeling was explored, utilizing a polylactide-caprolactone absorbable vein coupler model (PAVCM), which was designed to simulate a non-absorbable counterpart system with the sole exception of being absorbable. Methods Six New Zealand white rabbits were used. After transection of the jugular vein, 2 PAVCMs were placed, 1 at each transected end. The stumps were slipped through the PAVCMs, and the venous wall was everted $90^{\circ}$ to achieve intima-to-intima contact. Reanastomosis of the transected jugular vein was performed bilaterally in 3 rabbits. In the other 3 rabbits, the jugular vein (20 mm) harvested from one side was interpositionally grafted to the jugular vein on the opposite side to ease the anastomotic tension. Patency testing, ultrasonography, and histologic assessments were conducted postoperatively at weeks 2, 4, 12, 16, 22, and 26. Results All anastomotic sites were patent, without stenosis, occlusion, or dilatation. In the histologic sections, immature endothelial regeneration was observed at week 2, which was completed by week 4. Regeneration of the tunica media was noted at week 12. Between week 22 and week 26, the tunica media fully regenerated and the coupler dissipated entirely. Conclusions Despite the absence of a coupler to act as an anastomotic buttress, the structure and function of all the vessels appeared normal, even histologically. These outcomes are true milestones in the development of an absorbable vein coupler.