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ORIGINAL ARTICLE |
Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford, UK
David P Taggart, FRCS, Tel: +44 1865 221121, Fax: +44 1865 220244, Email: david.taggart{at}orh.nhs.uk, John Radcliffe Hospital, Headley Way, Headington, Oxford, OX3 9DU, United Kingdom.
ABSTRACT
A novel technique to achieve total arterial grafting, using a radial artery jump graft from the anterior descending coronary artery to the posterior descending artery, was employed in a preliminary series of 10 patients. All radial artery grafts were patent. This was confirmed using the SPY intraoperative fluorescence imaging system. There were no postoperative complications in any patient, and all were discharged uneventfully.
Key Words: Coronary Artery Bypass • Off-Pump • Coronary Disease • Thoracic Surgical Procedures
INTRODUCTION
The last decade has seen a gradual evolution in the performance of coronary artery bypass grafting (CABG) with the introduction of off-pump CABG and the use of other arterial grafts in additional to a single internal thoracic artery (ITA). Studies report that off-pump CABG reduces morbidity and mortality, while bilateral ITA grafts improve survival in comparison to the use of a single ITA graft, and radial artery (RA) grafts have superior patency to vein grafts. However, the potential merits of these strategies are still the subject of vigorous debate, and none has become the accepted standard of care. Nevertheless, a combination of these strategies potentially enables an off-pump no-touch aortic technique that reduces the incidence of stroke.1 We describe another novel approach to achieve this, based on in-situ bilateral ITA grafts to the 2 best left-sided coronary vessels and an RA graft from a disease-free segment of the distal left anterior descending coronary artery (LAD) to the posterior descending artery (PDA), when there is at least 80% stenosis in the proximal PDA or right coronary artery (RCA).
PATIENTS AND METHODS
Preliminary experience with the new technique was obtained in 10 patients, aged 49 to 77 years, who required an no-touch aortic approach. All patients had at least 80% stenosis in the proximal PDA or RCA. CABG was performed via a median sternotomy in all cases. Both ITA were harvested as skeletonized conduits and bathed in a swab containing papaverine. The RA was harvested and stored in heparinized blood containing phenoxybenzamine and verapamil prior to performing the anastomosis. Using standard off-pump techniques, the heart was positioned and stabilized without compromising hemodynamics. There were predominantly 2 graft configurations based on the ITA (Table 1
): either the left ITA was anastomosed to the LAD, with the right ITA anastomosed to the obtuse marginal coronary artery as a composite graft from the left ITA; or the right ITA was grafted to the LAD and the left ITA to the obtuse marginal. In some situations, the left ITA was used as a sequential graft to the diagonal and LAD, with the right ITA placed as a composite graft to the obtuse marginal system. The heart was then repositioned, the distal end of the RA was anastomosed to the PDA, and then anastomosed proximally to a disease-free area of the distal LAD of at least 1.5 mm in diameter. Continuous electrocardiographic and hemodynamic monitoring was carried out to ensure stability throughout the procedure. Following completion of the anastomoses, graft patency was confirmed using the SPY intraoperative fluorescence imaging system (Novadaq Technologies, Inc., Canada).2
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All 10 patients were male with 3-vessel coronary disease (Table 1
). All RA grafts were patent, and this was confirmed in the operating room with the SPY system which provides visual images of graft patency (Figure 1). There were no postoperative complications in any patient, and they were all discharged uneventfully.
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While numerous configurations of arterial conduits to achieve myocardial revascularization have been described, there are relatively few reports of coronary-to-coronary grafts. These have included the use of a free right ITA graft from a normal RCA to the posterolateral left ventricular artery, RA from the proximal to distal LAD bypassing a stenosed segment, and the use of saphenous vein from the RCA to perform sequential grafts to branches of the left coronary artery.3,4 These techniques have generally been used only as a last option, either because of lack of adequate conduit length or due to a porcelain aorta.
To our knowledge, there has been no previous report of the use of this RA "jump" graft from the distal LAD to revascularize the PDA territory. However, we feel that this strategy has several distinct practical and theoretical advantages over other techniques attempting to achieve an off-pump, total arterial graft, no-touch aortic technique. The major practical advantage of this technique is that it eliminates 2 well-recognized potential problems from the more frequently practiced approach of using a composite RA graft from the ITA: the risk of technical failure in the anastomosis (2% in our own unpublished series); and the occurrence of steal phenomena. Both problems are more likely to occur when the RA is significantly larger than the ITA, and the steal phenomenon even more so when a large composite RA graft from a relatively small ITA is placed to a coronary vessel where the stenosis is more severe than in the coronary vessel being served by the ITA. In contrast, the RA is often better matched to the size of the distal LAD, and by definition, cannot either risk damage to the ITA or promote the risk of steal in the more proximal LAD territory. Furthermore, concerns regarding the adequacy of blood flow from a single-inlet ITA are allayed by flow reserve studies using dobutamine stress echocardiography, which confirmed that the single-inlet ITA is able to increase its flow in response to myocardial demand, without any objective evidence of inducible regional ischemia.5 Although concerns regarding the advantage of RA usage in insulin-dependent diabetic patients have been raised, there is as yet no definitive evidence to suggest that RA is inferior to saphenous vein as a conduit for CABG in any population.6
The theoretical rationale for this approach is based on the frequent observation of long-term follow-up angiograms in patients requiring redo surgery, which usually demonstrate that the ITA graft has remained patent and the distal LAD disease free. We speculate that this may be due to a protective effect of the increased nitric oxide release from the ITA in comparison to either saphenous vein and RA grafts.7 It is known that by virtue of its laminar flow promoting increased shear stress, the endothelium of the ITA elutes nitric oxide into the LAD, and this has been sampled intraoperatively in significantly increased concentrations from the anterior interventricular vein.8 This may contribute to the long-term patency of the ITA-to-LAD graft. Finally, there is increased flow in composite grafts compared to simple grafts, and a similar increase in ITA graft flow is likely to occur in this configuration, due to additional distal vascular bed supply through the RA, but without the risk of steal in the LAD territory.9 Intuitively, it is likely that grafts with higher intraoperative flows have better long-term patency outcomes than those with poor flows, and we anticipate that the use of the distal LAD segment for the proximal anastomosis of the RA would allow the benefits of the ITA-to-LAD graft to be extended to the PDA graft.
Although there are intuitive and theoretical reasons to believe that these grafts should remain patent, without follow-up angiography to confirm long-term graft patency, it cannot be excluded that this technique could, in some unrecognized fashion, predispose to graft failure. However our cardiologists have been reluctant to perform repeat angiography because of the small but potentially disastrous risk of damaging an ITA, with its potential implications for other composite grafts. Nevertheless, recognizing the fact that failure of the RA graft is more prone to occur when there is less than 80% stenosis in the native coronary artery, we have reserved this technique for those with stenosis exceeding 80%. Certainly in clinical terms, no patient has presented with recurrent angina.
This preliminary study suggests that off-pump total arterial grafting employing a no-touch aortic technique can be performed safely using this configuration of internal thoracic and radial arteries to perform a jump graft from the left anterior to the posterior descending artery.
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:143-146
© 2009 by SAGE Publications
DOI: 10.1177/0218492309103294
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