Keywords
Gastroepiploic artery; Redo coronary artery bypass grafting
Reoperative coronary artery bypass grafting (CABG) is associated with
increased patient mortality and morbidity as compared to primary
coronary revascularization.1-5 This increased risk is
due not only to the potential for increased patient comorbidities, but
also to the risk of injury to cardiovascular structures on re-entry and
mediastinal dissection.1-5 Potential pitfalls during
re-entry and mediastinal dissection in reoperative CABG include injury
to internal thoracic artery or vein grafts, native coronary vessels, the
right ventricle, or the innominate vein.1 Therefore, a
meticulous image-guided and multidisciplinary team-based approach for
preoperative assessment of reoperative cardiac surgery has been
proposed.6 Furthermore, novel techniques are required
in patients undergoing reoperative CABG with limited bypass conduit
options.
In this issue of the Journal, Shiraishi et al. document the outcomes of
reoperative CABG using the right gastroepiploic artery (RGEA) through a
left anterolateral thoracotomy at a single cardiac
center.7 The goals of the study are to specifically
examine perioperative morbidity and mortality and to assess the impact
of reoperative CABG with RGEA grafting through a left anterolateral
thoracotomy by evaluating cardiac functional values between pre- and
postoperative status. This is a retrospective cohort study examining
the outcome of eleven patients from a single institution that underwent
reoperative CABG with RGEA and RGEA-saphenous vein composite grafts
through a left anterolateral thoracotomy and midline epigastric
approach. Ten of these patients underwent off-pump CABG. Bypass target
vessels of both RGEA and RGEA-saphenous vein composite grafts included
the left anterior descending, diagonal, circumflex, and right coronary
arteries. All grafts were patent on angiogram or coronary computed
tomography at postoperative day seven. No in-hospital deaths were
observed. Postoperatively, improvements were observed in left
ventricular end-diastolic volume, left ventricular end-systolic volume,
and left ventricular ejection fraction. From these findings, the
authors concluded that in select patients, off-pump reoperative CABG
with RGEA grafting through a left anterolateral thoracotomy is a safe
and effective surgical procedure.
Shiraishi et al. present an interesting and topical premise.
Historically, the RGEA was first proposed for indirect myocardial
revascularization in the 1960’s.8 In 1987, Pym et al.
first described direct revascularization of the right coronary artery
and obtuse marginal branches using RGEA grafts.9 That
same year, Suma et al. described the use of RGEA for reoperative
coronary revascularization of the left anterior descending artery
through a transdiaphragmatic approach in two
patients.10 The transdiaphragmatic approach
facilitates avoidance of both full sternotomy and cardiopulmonary
bypass.7 Since that time, others have described off
pump reoperative CABG using the RGEA, primarily to the right coronary
artery circulation. 11, 12, 13, 14, 15 Nevertheless,
the RGEA is an infrequently used bypass conduit.
As Shiraishi and colleagues concede, RGEA use should be limited to
select appropriate bypass candidates.7 This judicious
patient selection is reflected in their small cohort size. Similar to
radial artery bypass grafts, RGEA graft patency rate is highly dependent
on the degree of stenosis of the native target
vessel.16, 17 When used to bypass native vessels with
greater than 90% stenosis, RGEA patency rates were reported as 94.7%
and 90.2% at 5 and 8 years after surgery,
respectively.18 Therefore, the RGEA has good patency
when bypassing critically stenosed or occluded native coronary arteries;
however, native coronary competitive flow may lead to RGEA bypass spasm
and occlusion. Its small caliber and predisposition to vasospasm have
limited widespread RGEA use as a bypass graft.13, 19
Despite these limitations, there has been more recent interest in RGEA
grafts for full arterial revascularization. Within the last year, Kim
and colleagues have shown comparable results between the ten year
patency rates of both RGEA and right internal thoracic artery composite
grafts.20 Furthermore, Yamamoto et al. recently
published patency rates for free gastroepiploic artery (GEA) bypass
grafts.21 The early patency rate of free GEA grafts
was 98.6%. The long-term patency rates of the free GEA grafts were
96.5%, 95%, and 86.6% at 5, 10, and 15 years,
respectively.21
As cardiac surgeons, we face an increasing number of complex patient
presentations, including reoperations. Knowledge of a broad range of
bypass conduit options will surely strengthen our armamentarium for
reoperative CABG when there may be limited conduit availability. I
commend Shiraishi and colleagues for their surgical ingenuity and
mastery.