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Royse et al. Vessel Plus 2020;4:5 I http://dx.doi.org/10.20517/2574-1209.2019.34 Page 3 of 22

Table 1. Patency and perfect patency for asymptomatic patients receiving conventional angiography 13 ± 3 years
postoperative with at least one internal mammary artery, radial artery and saphenous vein graft
Comparison Perfect patency n (%) P Patency n (%) P
IMA, RA, SVG < 0.001 0.015
IMA vs. RA 60/62 (96.8) 0.461 60/62 (96.8) 0.298
71/77 (92.2) 72/77 (93.5)
IMA vs. SVG 60/62 (96.8) < 0.001 60/62 (96.8) 0.013
10/57 (17.5) 47/57 (82.5)
RA vs. SVG 71/77 (92.2) < 0.001 72/77 (93.5) 0.055
10/57 (17.5) 47/57 (82.5)
Arterial, SVG < 0.001 0.009
Arterial vs. SVG 131/139 (94.2) < 0.001 132/139 (95.0) 0.009
10/57 (17.5) 47/57 (82.5)
IMA: internal mammary artery; RA: radial artery; SVG: saphenous vein graft.

(RAY) or BIMA-Y (BIMAY) is usually larger in diameter proximal to the Y graft than distal to the Y graft,
as it needs to be to provide additional flow to the second conduit as well as the continuation of the LIMA.
These findings are normal and expected and do not represent a pathological state.

The most common alternative arterial conduit is the radial artery (RA) and, infrequently, the gastroepiploic
artery (GEA). Controversy continues to surround the use of RA in CABG, its perioperative and
intraoperative management and long-term outcomes. Data outcomes using statistics that estimate
future events (Kaplan-Meier actuarial survival) suggest a progressive decline in patency of RA. This is
discordant with the directly measured angiographic findings of RA, which are also “binary” - being either
patent and normal or occluded/string sign. There are no serial angiographic reports in the literature of
normal RA grafts in the early postoperative period, and then later developing progressive atherosclerosis
and eventual occlusion. In our institutional experience of more than 20,000 RA use, we also have not
documented progressive atherosclerosis leading to RA occlusion in serial angiograms. The longest duration
postoperative for RA angiography in our experience is 22 years, whereby the RA appeared patent and
normal.

In a research angiographic series we conducted with patients selected to have received all three IMA, RA
and SVG conduits (n = 50) at 13 ± 3 years postoperative, we found that the Patency and Perfect Patency was
the same for IMA (97%, 97%) and almost the same for RA (94%, 92%), respectively (one RA was diseased
at the time of implantation, and remained patent and diseased). The patency of SVG was significantly lower
(83%) and the Perfect Patency of SVG was only 18% [Table 1]. There were no significant differences in
perfect patency or patency between IMA and RA, despite IMA being almost exclusively grafted to the LAD
and RA being grafted to the other two territories.

The angiographic appearance of RA and IMA appeared to be the same in the late period and different to
SVG indicating a different mode of graft failure.

Predicting future failure of grafts
It is understandable that a heavily diseased SVG may occlude in the foreseeable future - from logical first
principles. Equally, a normal appearing arterial graft at angiography would suggest that this conduit is
not likely to fail in the foreseeable future - from logical first principles. A further extension to the logical
argument is that SVG is first exposed to the arterial blood pressure and flow rates on the day of surgery.
These newly introduced factors may then lead to the development of accelerated atherosclerosis, which can
be observed in the cardiac surgery, vascular surgery and renal access surgery domains. Arterial conduits
have been exposed to the arterial blood pressure and flow since birth and should therefore not be expected
to develop sudden or rapidly progressive atherosclerosis after being transplanted to the coronary circulation
and being exposed to the same or similar blood pressure and high flow state.