Wall thickness
Grafts assessed using IVUS had, on average, thicker walls than the
surgically prepared veins assessed by histology. There was a trend
towards a difference in mean wall thickness according to the harvest
technique and pressure test used (test for interaction between the
pressure test and harvest technique, p=0.070). In patients randomised to
conventional harvest, those in the low-pressure group had, on average, a
thinner vessel wall compared to those in the high-pressure group (mean
difference MD (low minus high) = -0.059mm, 95%CI -0.12, +0.0039,
p=0.066). By contrast, in patients randomised to pedicled harvest the
wall thickness was similar irrespective of distension pressure (MD (low
minus high) = +0.019mm, 95%CI -0.038, +0.075, p=0.51).
Comparing the results by harvest method in patients randomised to a high
pressure test, grafts with a pedicle had a thinner vessel wall than
those in the conventional harvest group (MD (pedicle minus conventional)
= -0.057mm, 95%CI -0.12, +0.0037, p=0.066). For those randomised to a
low-pressure test, wall thicknesses were similar for the two harvest
techniques (MD (pedicle minus conventional) = +0.021mm, 95%CI -0.038,
+0.081, p=0.48, Figure 2, Table 4, Appendix Table A6 ).