Early remodeling of lower extremity vein grafts: Inflammation influences biomechanical adaptation
Received 12 October 2007; accepted 7 January 2008. published online 28 April 2008.
Background
The remodeling of vein bypass grafts after arterialization is incompletely understood. We have previously shown that significant outward lumen remodeling occurs during the first month of implantation, but the magnitude of this response is highly variable. We sought to examine the hypothesis that systemic inflammation influences this early remodeling response.
Methods
A prospective observational study was done of 75 patients undergoing lower extremity bypass using autogenous vein. Graft remodeling was assessed using a combination of ultrasound imaging and two-dimensional high-resolution magnetic resonance imaging.
Results
The vein graft lumen diameter change from 0 to 1 month (22.7% median increase) was positively correlated with initial shear stress (P = .016), but this shear-dependent response was disrupted in subjects with an elevated baseline high-sensitivity C-reactive protein (hsCRP) level of >5 mg/L. Despite similar vein diameter and shear stress at implantation, grafts in the elevated hsCRP group demonstrated less positive remodeling from 0 to 1 month (13.5% vs 40.9%, P = .0072). By regression analysis, the natural logarithm of hsCRP was inversely correlated with 0- to 1-month lumen diameter change (P = .018). Statin therapy (β = 23.1, P = .037), hsCRP (β = −29.7, P = .006), and initial shear stress (β = .85, P = .003) were independently correlated with early vein graft remodeling. In contrast, wall thickness at 1 month was not different between hsCRP risk groups. Grafts in the high hsCRP group tended to be stiffer at 1 month, as reflected by a higher calculated elastic modulus (E = 50.4 vs 25.1 Mdynes/cm2, P = .07).
Conclusions
Early positive remodeling of vein grafts is a shear-dependent response that is modulated by systemic inflammation. These data suggest that baseline inflammation influences vein graft healing, and therefore, inflammation may be a relevant therapeutic target to improve early vein graft adaptation.
Brigham and Women's Hospital, Harvard Medical School, Boston, Mass.
Correspondence: Michael S. Conte, MD, Associate Professor of Surgery, Harvard Medical School, Brigham and Women's Hospital, Division of Vascular Surgery, 75 Francis St, Boston, MA 02215.
Competition of interest: none.
Supported by funding from the National Heart, Lung, and Blood Institute (HL75771) to Drs Conte, Owens, and Rybicki, the Clinical Investigator Training Program, Harvard-MIT Division of Health Sciences and Technology to Dr Owens; NIBIB (K23-882) and the Whitaker Foundation to Dr Rybicki.
ABSTRACT