Histological changes of the unligated vein wall adjacent to the central venous catheter after open cutdown in rats.

Kim, Seongyup; Kim, Younglim; Moon, Suk-Bae

BACKGROUND The sequelae of a central venous cutdown usually include venous deformity causing venous stenosis or stricture. However, the cellular mechanisms causing these deformities have not been elucidated. METHODS Silicone 2.7-Fr catheters were placed via the right external jugular vein of 16 rats with the cutdown method. After fixation with formalin at scheduled intervals (1week, 2weeks, 4weeks, and 8weeks; 4 rats in each group), the vein segment with the catheter in situ was harvested. Histological changes in the vein wall were studied and serially compared with light microscopy; standard hematoxylin-eosin staining, Masson's trichrome staining, van Gieson's elastin stain, and immunohistochemical stain against α-actin. RESULTS Pericatheter sleeve formation, circumferential smooth muscle cell proliferation and infiltration into the pericatheter sleeve by direct contact were noted in all 4 rats of 1-week model; this indicated the initiation of neointimal hyperplasia. The neointimal hyperplasia was located inside the elastin layer. At 2weeks, the SMCs stained faintly but the components of the vein wall were largely replaced by collagen. The proliferation and infiltration of SMCs stabilized at 4weeks and no SMCs were stained around the catheter. At 8weeks, luminal narrowing was noted and the venous wall was composed mainly of collagen. CONCLUSIONS Circumferential neointimal hyperplasia occurred after surgical cutdown of the external jugular vein in a rat model and was caused by SMC activation, proliferation, and infiltration into the pericatheter sleeve.