Original article
Adult cardiac
High-Pressure Distention of the Saphenous Vein During Preparation Results in Increased Markers of Inflammation: A Potential Mechanism for Graft Failure

https://doi.org/10.1016/j.athoracsur.2011.10.035Get rights and content

Background

Coronary artery disease is the single leading cause of death in the United States. Commonly it is treated with coronary bypass grafting using the saphenous vein (SV) or internal mammary artery (IMA) as a conduit. Unfortunately, the SV has much lower patency rates compared with the IMA. Several hypotheses exist as to why occlusion occurs more commonly in SV grafts than in IMA grafts. However detailed studies in this area have been limited. This study investigates the effects of pressure distention on inflammation in SV conduit used in coronary artery bypass grafting (CABG).

Methods

Saphenous vein distention pressure was measured intraoperatively during 48 CABG procedures. A segment of SV was excised from the conduit before distention. Because the vein was used for coronary artery grafting, sequential pieces were archived for evaluation. Real-time polymerase chain reaction (RT-PCR) and immunohistochemical analyses were performed to investigate a change in the expression of biomarkers.

Results

Upregulation of various biomarkers occurred. These biomarkers included scavenger receptors A and B (SR-A, SR-B), toll-like receptors 2 and 4 (TLR2, TLR4), platelet endothelial cell adhesion molecule (PECAM), vascular cell adhesion molecule (VCAM), and intercellular cell adhesion molecule (ICAM) in segments of SV that were subjected to distention. Immunohistochemical results mirrored RT-PCR findings. A significant correlation was observed between biomarkers and pressure values.

Conclusions

These studies demonstrate that markers of inflammation are upregulated in response to SV distention. The data suggest that the pressure used in graft preparation procedures should be regulated to avoid inflammation and its potential to induce graft failure.

Section snippets

Patient Demographics

Saphenous vein samples were collected from 48 patients (39 men, 9 women) undergoing elective CABG. The procedures described herein were approved by the Institutional Review Boards of The University of Nebraska Medical Center and were carried out according to the principles outlined in the Declaration of Helsinki. All patients requiring 1- to 5-vessel bypasses using an SV graft were included (Table 1).

Intraoperative Saphenous Vein Harvest

Saphenous vein harvesting, as illustrated in Figure 1, was done by 2 physician assistants who

mRNA Levels in Distended Vein Segments

Reverse transcriptase–polymerase chain reaction (RT-PCR) was performed on all SV segments. Segment 0 received no distention and segment Last was located immediately adjacent to the tip of the vessel cannula. mRNA expression was compared across all segments. As seen in Figure 2A, a significant difference (p ≤ 0.05) in the expression of cell adhesion molecules was observed when comparing the nondistended segment (segment 0) to segments 1, 2, and Last. ICAM-1 was significantly upregulated when

Comment

Previous studies have looked at the increase in adhesion molecules after SV distention. However these studies examined immunohistochemical findings only and did not evaluate gene expression changes after vein preparation. This study set out to look at these and other markers of inflammation using RT-PCR in distended SV. This study is unique in that not only were nondistended veins compared with distended veins but also the intervening graft segments were investigated for mRNA expression

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