1Boston University School of Medicine, Boston, MA, USA, 2Saint Vincent Hospital, Worcester, MA, USA.
Objectives: Residual clot strands within the excised saphenous vein are an increasingly recognized squeal of endoscopic vein harvest (EVH). These clots seem to be provoked by the stagnation of blood associated with this technique and can be prevented by administering 5000 IU of heparin systemically just prior to EVH. However, heparin administration increases bleeding during concurrent sternotomy/IMA harvest and is not used routinely by most surgical groups. We tested whether lower heparin doses also prevent clot formation during EVH.
Methods: Seventy consecutive CABG patients underwent EVH with no preceeding systemic heparin dose (n=11) or with prior heparin administered using four different regimens: 1) 200 IU/kg (n=12), 2) 5000 IU bolus (n= 17), 3) 2500IU (n=20) or 4) 1000 IU (n=10). After removal from the leg, veins were cannulated with a 1F optical coherence tomography imaging wire (OCT, LightLab, Corp) and the volume of retained intraluminal clot measured by a technician unaware of the treatment group. Perioperative outcomes were assessed.
Results: Residual clot was a consistent finding in the groups that received no heparin (3.80±4.4 mm3) or only 1000 IU before EVH (2.59±5.5 mm3)(FigA). In contrast, all heparin regimens of 2500 IU or more led to a significant reduction in clot volume (0.26±0.53 mm3, p=0.024 vs. control, FigB) with no statistically significant difference between groups (0.33±0.77 mm3, 0.20±0.27 mm3, 0.25± 0.47 mm3 after 200 IU/kg, 5000 IU, 2500 IU, respectively). Intraoperative blood loss and perioperative blood product requirements were similar in all groups.
Conclusion: Using an intraoperative imaging technique with unsurpassed sensitivity for quantifying residual clot, this study revealed that the amount of residual clot provoked by EVH was not significantly reduced by 1000 IU compared to no systemic heparinization. However, increasing the dose to 2500 IU significantly reduces clot retention with no added benefit at higher doses. We therefore recommend 2500 IU of heparin to be administered just prior to EVH as an effective and most benign way to improve conduit quality.
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