Warren J. Gasper, Hugh Alley, Maria Aleshin, Joseph Rapp, Marlene Grenon, Michael S. Conte, Christopher D. Owens
Vascular Surgery, University of California San Francisco, San Francisco, CA.
OBJECTIVES: Lower extremity vein bypass grafts (LEVBG) undergo geometric remodeling within the first month of surgery, which directly correlates with subsequent patency. Veins are less vasoreactive than arteries, and the extent of biochemical adaptation by vein grafts in the arterial environment is unknown. Flow-mediated vasodilation (FMD) measures endothelial-dependent vasodilation in response to hyperemia. We hypothesized that geometric remodeling of venous conduits would be correlated with endothelial function after LEVBG.
METHODS: Patients undergoing LEVBG were prospectively enrolled. Brachial artery FMD was performed at baseline, and vein graft FMD studies were performed at intervals following LEVBG.
RESULTS: A total of 57 patients, median age 64 years (IQR 61-71) with median follow-up 17 months (IQR 10-32), were included. Most patients (91%) were male, 75% were white, 49% had diabetes, 81% were on a statin, and the median baseline hsCRP was 6.2mg/L (IQR 2.4-10). Most vein grafts (68%) were single-segment great saphenous vein, and 63% were femoral-popliteal bypasses. Mean baseline brachial artery FMD was 7.6±4.5%. Mean graft lumen diameter increased from 4.3±0.8mm at surgery to 4.7±0.8mm at 3 months. There was a significant correlation between initial lumen diameter and 0-3 months remodeling, r=-0.48 p=0.02. No correlation was seen between brachial FMD and vein graft FMD. Mature (≥12 months) grafts had significantly higher FMD than early (3 months) grafts (4.5±2.7% vs. 0.6±1.9%, p<0.0005) and there was a significant positive correlation between early and late graft FMD, r=0.64 p=0.01. We did not observe a significant correlation between early graft remodeling and either brachial or vein graft FMD.
CONCLUSIONS: LEVBG patients have endothelial dysfunction demonstrated by impaired brachial artery FMD. Veins grafts exhibit recovery of endothelial function over the first year of implantation. However, early geometric remodeling appears asynchronous from physiologic endothelial recovery in the arterialized vein.
AUTHOR DISCLOSURES: M. Aleshin: Nothing to disclose; H. Alley: Nothing to disclose; M. S. Conte: Nothing to disclose; W. J. Gasper: Nothing to disclose; M. Grenon: Nothing to disclose; C. D. Owens: Nothing to disclose; J. Rapp: Nothing to disclose.
Posted April 2013