Page 193 - Read Online

Harik et al. Vessel Plus 2023;7:30 https://dx.doi.org/10.20517/2574-1209.2023.124 Page 5 of 16

[21]
arterial grafts , and injury to the vein graft intima, often incurred intraoperatively during harvesting, is a
risk factor for graft failure. The conventional open approach for SVG harvesting removes the perivascular
tissue with subsequent manual distension of the graft with heparinized saline up to pressures of
[22]
600 mmHg . The no-touch approach for SVG harvesting preserves the perivascular tissue with the aim
[23]
of minimizing damage to the graft, reducing intimal injury, and thus reducing vein graft occlusion, and has
[23]
previously been described . Small, single-center RCTs [24-26] have demonstrated lower rates of graft
occlusion with no-touch SVG harvesting. One large trial, the Graft Patency Between no-touch Vein
Harvesting Technique and Conventional Approach in Coronary Artery Bypass Graft Surgery (PATENCY)
trial randomized 2,655 CABG patients to either conventional or no-touch harvesting, and found that at
[27]
1-year postoperative follow-up, the risk of SVG occlusion was decreased in the no-touch compared with the
conventional harvesting group (3.7% vs. 6.5%, OR 0.56, 95%CI: 0.41-0.77; P < 0.001); however, the incidence
of major adverse cardiac and cerebrovascular events was not different between groups (3.8% vs. 4.3%,
OR 0.89, 95%CI: 0.61-1.29; P = 0.53). The no-touch group had a higher incidence of local harvest site issues
including exudation (4.3% vs. 1.9%; P < 0.01), numbness (23.2% vs. 17.8%; P < 0.01), and edema before
discharge (19.0% vs. 12.9%; P < 0.01); however, there was no difference in the need for re-intervention on
the wound prior to hospital discharge (0.9% vs. 0.4%; P = 0.09). The need for re-intervention or pain at the
harvest site at one year was similar between groups. The ongoing SWEDEGRAFT trial (NCT 03501303) will
provide additional information on this important topic .
[28]
Endoscopic vein harvesting (EVH) was first introduced with the aim of decreasing the incidence of local
[29]
harvest site complications and postoperative pain (the technique has been previously described ), but may
risk endothelial injury secondary to greater intraoperative manipulation, as discussed above. A meta-
analysis of 22 studies (five RCTs) and 27,911 patients with at least one-year follow-up found that local
harvest site complications occurred less frequently with EVH than with open vein harvesting (OVH) (0.75%
[30]
vs. 2.92%, OR 0.19, 95%CI: 0.12-0.30; P < 0.001) , and with no difference in all-cause mortality (incidence
rate ratio [IRR] 0.98, 95%CI: 0.48-1.99; P = 0.95) and major adverse cardiac events (IRR 1.01,
95%CI: 0.12-0.31; P < 0.001) between EVH and OVH. However, at one to five years, EVH was associated
with lower SVG patency than OVH (73.7% vs. 77.81%, OR 0.80, 95%CI: 0.70-0.91; P < 0.001). Similarly,
another meta-analysis of five studies and 6,504 grafts with angiographic follow-up found that EVH was
[31]
associated with a higher risk of graft failure (OR 1.38, 95%CI: 1.01-1.88; P < 0.0001), and a similar meta-
analysis of 11 studies reported lower SVG failure with open vein harvesting at a mean 2.6-year follow-up
[32]
(17.7% vs. 24.9%; OR: 0.61; 95%CI: 0.43-0.87; P = 0.01) . An additional consideration for SVG harvesting is
the type of intraoperative storage solution used, as this may also affect vein graft integrity and, therefore,
[33]
risk of failure . Current debate centers on commonly used storage solutions such as saline, pH-buffered
saline solutions, as normal saline solution may be detrimental to the endothelial integrity of the vein graft,
or blood solutions. Evidence from ex-vivo studies and animal studies on the relationship between vein graft
solution and vein graft failure, and on the optimal storage solution, has remained inconclusive. There has
not been a randomized, blinded trial comparing graft patency by vein graft storage solution, and
consequently, variations in clinical practice persist.

External stenting
Late vein graft failure, or that occurring at the first postoperative year or later, is characterized by intimal
hyperplasia and atherosclerosis, processes to which vein grafts are particularly susceptible [9,21,34,35] . External,
cobalt-chromium mesh stenting devices have been introduced to prevent this process [36-38] , and a series of
RCTs, the Venous External Support Trials (VEST), were conducted to test these devices. VEST I enrolled 30
patients randomized to receive a single stented SVG to either the right or the circumflex coronary territories
(30 grafts), while one or more SVGs were not stented (39 grafts). Intravascular ultrasound assessment found
that the area of intimal hyperplasia was smaller in the stented group (mean 4.37 mm ) than in the non-
2