Supplemental oxygen controls cellular proliferation and anastomotic intimal hyperplasia at a vascular graft-to-artery anastomosis in the rabbit

Abstract

Purpose: The purpose of this study was to determine whether the administration of 40% supplemental oxygen (O ( 2) ) will decrease cellular proliferation and intimal hyperplasia (IH) at a prosthetic vascular graft (PVG)-to-artery anastomosis.

Methods: Twenty New Zealand white rabbits underwent placement of a 3-mm polytetrafluoroethylene graft in their infrarenal aorta. Four groups of five rabbits were placed either in a normoxic (21%) environment or in a 40% supplemental O ( 2) environment for 7 or 42 days. Twenty-four hours before the rabbits were humanely killed for aortic graft harvest, BrDU (5-bromo-2'-deoxyuridine) was injected into the rabbits intraperitoneally. Image analysis (Bioquant) morphometrics were used to measure cells with BrDU staining and intimal areas at the distal anastomosis. Cellular proliferation is defined as positively staining BrDU cells divided by all cells in the artery wall. IH is reported as a ratio between the intimal area and the medial area to standardize the varying aortic size and degree of aortic fixation among rabbits. The Student t test was used to compare cellular proliferation and IH between control and O ( 2) -treated rabbits.

Results: Cellular proliferation in the intima at 7 days was significantly reduced in the O ( 2) -treated animals (1.7% +/- 1%) versus the control animals (28.6% +/- 3%) ( P =.0001). The cellular proliferation in the intima at 42 days returned to preoperative levels in the O ( 2) -treated group (0.15%) and in the control group (0.11%) ( P = not significant). IH at 7 days was minimal, and no difference between the O ( 2) -treated group (0.017 +/-.006) and the control group (0.009 +/-.03) ( P = not significant) was found. IH was significantly reduced at 42 days in the O ( 2) -treated animals (0.031 +/-.012) when compared with the control animals (0.193 +/-.043) ( P =.006).

Conclusions: Supplemental O ( 2) (40%) significantly reduces cellular proliferation and IH at the distal anastomosis of a PVG-to-artery anastomosis in the rabbit model.