Superior survival benefit, greater freedom from re-intervention, and less repeat operations have been reported with bilateral internal thoracic artery (BITA) grafting.1,2 Pedicled, as opposed to skeletonized right internal thoracic artery (RITA) grafting, may not be enough to reach the left or right coronary arteries without tension. Furthermore, bilateral pedicled harvesting of the internal thoracic arteries (ITAs) may carry a higher risk of sternal wound infection.3-6 It is noteworthy that a strikingly higher incidence of deep sternal infections is reported in patients with double-pedicled arterial grafts.3,6 In light of these reported disadvantages of bilateral pedicled grafts, ITA skeletonization has been advocated to minimize sternal devascularization and wound healing problems while maximizing the harvested length of the ITA.3,6 In the current study, coronary artery bypass grafting (CABG) was performed primarily with bilateral internal mammary and gastroepiploic arteries. Our initial experience showed a higher delayed incidence of diffuse skeletonized RITA graft stenosis, which prompted us to use it as a pedicled graft. RITA was also mainly used as an in situ graft rather than a composite graftwhenever possible. Deep sternal wound infections were not found to be a problem in those pedicled bilateral ITAs. Although this might have partly been due to relatively small patient population, the ITAs may safely be used as pedicled grafts with careful attention to infection prophylaxis. Some of the advantages of pedicled grafting include ease of handling, decreased harvesting time, and a lower tendency for graft dissection. Furthermore, bilateral pedicled grafting may not necessarily compromise sternal perfusion. By minimizing injury to the branch vessels supplying the sternum and the surrounding muscles, we believe that pedicled BITA grafts can safely be used. Because of superior survival benefits of BITA and potential benefits of pedicled BITA, it's use should be encouraged more if it is not a cause of delayed sternal healing or deep wound infections.

Stroke occurred in 2 patients; due to a massive gas cerebral embolic event related to air introduction by the blower during on-pump beating heart bypass in one patient and atheromatous embolism after conventional cardiopulmonary bypass in another patient. Both patients died from pneumonia. There were 43 cases of re-exploration for bleeding. This high reoperative rate was thought to be related to high-dose preoperative loading of clopidogrel. In our hospital, all emergent CABG patients are loaded with high doses of clopidogrel in the emergency room before consultation with the cardiac surgeon. Postoperative low-cardiac output syndrome was also diagnosed in 41 patients.

The ITA graft patency was assessed 1 year postoperatively in 144 patients using either coronary angiography or CT angiography and the ITA grafts were patent in 138 cases. Four patients required surgical re-intervention due to ITA graft stenosis in 1 RITA and 3 LITAs.

Of the 162 pedicled BITA patients and 98 LITA only patients inclusive of 186 DM patients, there was no deep sternal wound infection (0/260). There was 1 case of sternal non union but this patient did not receive BITA grafting. There were 6 early mortalies [6/260 (2.3%)]. Because there was no deep sternal wound infection, no statistical analyses were performed with regards to the incidence of infection (Table 1).

The patency of in situ LITA is reported to be superior to free ITA grafts. In situ LITA bypass is currently considered as the gold standard for arterial conduits. BITA grafting has been associated with better long-term survival and decreased major cardiac events.1 Studies using RITA and LITA to bypass preferentially important vessels of the left coronary system showed excellent results,1,9-13 superior graft patency, and greater long-term freedom of cardiac events and reoperations1,9,13 Implantation of bilateral in situ ITAs has an added advantage of maintaining 2 separate ITA blood supplies to the myocardium, while avoiding additional anastomoses to fashion a composite graft. The left anterior descending artery was routinely revascularized with the in situ RITA; long-term results show that important left coronary vessels are revascularized with both in situ ITAs.1,9-12,14,15 Additional length of the RITA to the LAD could be gained with closure of the sternum. The use of the RITA to the LAD may be a better use of this graft rather than to the right coronary artery (RCA), since the latter has been associated with inferior results.12,13,16

Recent reports have shown superior survival benefit and freedom from recurrent angina with RITA usage,17,18 while other reports have raised concerns on the potential for increased risk of wound infection and dehiscence with extensive sternal devascularization.19,20 Several studies identified BITA grafting, especially in DM patients, as a risk factor for mediastinitis after CABG. They suggested avoiding BITA grafting in diabetic patients.21 Unlike pedicled ITA harvesting, skeletonization reduces the extent of chest wall devascularization and sternal wound related infectious complications, leaving veins, muscles and surrounding endothoracic tissue in place, and thereby decreasing the potential risk of postoperative wound complications. Indeed, occurrence of sternal wound infection appears consistently low after routine use of bilateral skeletonized ITAs.3,22 The sternal and anterior intercostal branches of the ITA originate either directly or as a common trunk from the ITA. The skeletonization of ITAs may preserve sternal and intercostal branches arising as a common trunk from the ITA, thus maintaining some collateral flow to the sternum.23 Substantial collateral blood flow to the sternum can be maintained in the absence of the ITA, provided that the sternal-anterior intercostal trunk is left intact. Skeletonization of the ITA often results in preservation of this common trunk, particularly if meticulous dissection is performed.6 However, we believe that the damage to the branch vessels in pedicled dissection is not different from that occuring with the skeletonization technique. Furthermore, the sternal-anterior intercostal trunk may be preserved in pedicled dissection in the current series, the branches were transsected 1 or 2 mm from the ITA as with the skeletonization technique. Ura et al.24 reported excellent results with BITA pedicled grafting, showing a very low incidence of mediastinitis (1.3%), especially in diabetic patients (2.1%). Therefore, we believe that the pedicled dissection may not be particularly more deleterious than the skeletonization technique, provided that careful attention is given to preventing infection.

The small patient cohort was a limitation in the present study. Patients who underwent pedicled BITA dissection had no more risk for wound complications than left ITA only patients. This may act to strengthen the positive influence of BITA with regards to these complications. Although BITA was not found to be a risk factor for wound complications in this study, a multivariable model, including data from the entire series, demonstrated that harvesting method (skeletonization versus pedicle ITA) as well as DM may be independent predictors of wound complications in a larger series of many other studies. Although the current results seemed to suggest that the bilateral pedicled ITA graft usage dose not result in a greater risk of complications than the skeletonized grafts or unilateral ITA graft use, further studies on a larger patient cohort should be conducted for a more definitive identification of the risks associated with bilateral pedicled grafts.

In conclusion, with careful attention paid to infection prevention such as avoiding excessive bone wax and implementing strict aseptic technique, the use of bilateral ITA pedicles may be safe and may not necessarily increase the risk of sternal wound related complications, or lead to compromise in graft performance.