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In certain coronary artery bypass grafting operations, the internal thoracic artery is not by itself adequate for complete arterial revascularization. Which graft should be used for revascularization of the right coronary artery is still a matter of debate.
From August 2000 through July 2005, we performed coronary–coronary bypass grafting on 48 patients (77.1% men, 22.9% women), whose mean age was 57.2 years (range, 40–75 yr). After completion of the internal thoracic artery anastomoses, we performed coronary–coronary bypass grafting with a remaining (distal) segment of the left (or, rarely, the full length of the free right) internal thoracic artery. The proximal and distal anastomoses of the internal thoracic artery to the right coronary artery were end-to-side. We preferred to use the right coronary ostium as the proximal anastomosis site where possible; otherwise, we used a disease-free segment of the right coronary artery.
A total of 192 anastomoses were performed (mean, 4.15 per patient); all used the bilateral internal thoracic arteries as conduits. There were no in-hospital deaths or perioperative myocardial infarctions. The duration of follow-up ranged from 1 to 46 months (mean, 9.6 mo). Follow-up angiography was performed in 24 patients (50%). The mean time to coronary angiography was 16.5 months (range, 7 days–2 years). The patency rate was 100%.
We conclude that coronary–coronary anastomosis by means of a distal segment of the internal thoracic artery can help to achieve complete arterial revascularization in selected patients.
The internal thoracic artery (ITA) is considered the best conduit for coronary artery bypass grafting (CABG) because of its known characteristics, such as superior long-term patency.1,2 The current trend is to use the ITA as much as possible in CABG operations,1,3–5 because current evidence suggests that it increases long-term survival and decreases the risk of angioplasty and reoperation, particularly when used bilaterally.6–9 Although complete revascularization is possible by using sequential anastomoses, coronary–coronary bypass grafting (CCBG) using only the ITA may be a viable alternative for complete arterial revascularization.
Currently, CCBG is indicated for use in the following conditions and circumstances: advanced calcification of the ascending aorta (porcelain aorta), advanced stenosis or occlusion of the subclavian artery, insufficient graft length, and the arterial conduit-sparing procedure. We ourselves also accept the following as indications for CCBG: previous total arterial revascularization with bilateral ITAs, insufficient flow of the in situ ITA graft, injury to the ITA during harvesting, the presence of a low-grade lesion of the right coronary artery (RCA), and situations in which using the ITA could lead to sternal and respiratory morbidity (such as insulin-dependent diabetes in elderly patients, chronic obstructive pulmonary disease, obesity, and fragility of the sternum).
A low-grade lesion of the RCA (50%–60% or less) has been associated with a low patency rate for any arterial or venous graft used in that position, causing a challenge for surgeons in selecting an appropriate conduit.10,11 In the present study, we investigated the technical feasibility, efficacy, and safety of CCBG for the revascularization of the RCA in appropriate cases.
Among 1,955 patients operated on from August 2000 through July 2005 by the same surgical team, 48 patients (2.5%) who underwent myocardial revascularization with CCBG were included. Of these patients, 37 (77.1%) were men and 11 (22.9%) were women. The mean age was 57.2 years (range, 40–75 yr). The baseline characteristics of the patients in the study group are listed in Table I.
Coronary–coronary bypasses with the ITA were performed in 3 different groups:
After a midline sternotomy, the LITA or the bilateral ITA was harvested with pedicle. All collateral branches were secured with a hemostatic medium or with small clips. Both ITAs were transected at a distal point (as distal as possible) after systemic heparinization, and papaverine hydrochloride (0.06 g/2 mL × 1 ampule diluted in 50 mL heparinized warm blood) was injected into the lumen. Then, the ITAs were wrapped in a sponge soaked in papaverine (0.06 g/2 mL × 3 ampules diluted in 50 mL heparinized warm blood). In order to prevent compression of the LITA, the pericardium was dissected in a reverse T shape. Cardiopulmonary bypass was initiated with aortic and 2-staged right atrial cannulation. Myocardial protection was accomplished with intermittent administration of isothermic blood cardioplegic solution, antegrade and retrograde. All anastomoses were performed under optical magnification (× 4.5) by means of a 6-mm chambered needle and continuous 8–0 polypropylene suture. After the completion of the other anastomoses, we prepared for CCBG the remaining LITA or RITA segments (2–5 cm; or, in the case of the free RITA, 12–15 cm). Appropriate sites for proximal and distal anastomoses were identified. Preoperative angiographic findings and intraoperative evaluations were used to identify disease-free sites of the RCA, and CCBG was not performed if no appropriate site was available. Then a proximal CCBG anastomosis (end-to-side) was performed first, to aid in determining the precise graft length during the antegrade injection of cardioplegic solution. After the completion of cardiopulmonary bypass, we topically applied Surgicel® (Ethicon, Inc., a Johnson & Johnson company; Somerville, NJ) soaked with papaverine and blood. With these techniques, we have not observed any ITA spasm for the last 5 years. The proximal and distal anastomosis sites for CCBG and the types of grafts are listed in Table II.
In 24 patients who gave consent, angiography was performed before discharge and at postoperative follow-up visits (which ideally but not consistently occurred at 1 week, 6 months, 1 year, and 2 years).
A total of 192 distal anastomoses were performed in 48 patients (mean, 4.15 ± 0.79 per patient). Complete arterial revascularization was performed in all cases (Table III). All anastomoses were performed with aortic cross-clamping.
There was no in-hospital death or perioperative myocardial infarction. In-hospital complications are listed in Table IV. Only 2 patients (4.2%) developed a nonfatal postoperative complication; both had a sternal wound infection.
Postoperative coronary angiography was performed in 24 patients (50%) (Figs. 1 and and2).2). Fourteen of the 48 patients underwent coronary angiography during the 1st postoperative week; of the 14 CCBGs that were evaluated, all were patent.
Follow-up ranged from 1 month to 46 months (mean, 9.6 ± 6.2 mo). During the follow-up period, no death or myocardial infarction was noted in any patient. Thirty-five patients (72.9%) underwent exercise testing in postoperative month 6, and no abnormality was found in any of them. At the 2nd follow-up, 30 patients (62.5%) underwent exercise testing, with abnormal results in only 1 case. One patient had recurrent anginal symptoms at 4 months and another patient at 12 months (4.2%). Both underwent coronary angiography; all grafts were patent. In 4 patients with nonsignificant (20%–25%) stenosis of the RCA, follow-up angiography revealed patent anastomoses but slightly narrowed free-ITA grafts (CCBG), most probably due to high flow in the native vessel. Two patients underwent angiography in the 2nd postoperative year, which showed a well-functioning CCBG. The mean time to coronary angiography was 16.5 ± 7.8 months (range, 7 days–2 years).
Coronary–coronary bypass grafting was first performed by Rowland and Grooters12 in 2 patients who had a calcified ascending aorta and insufficient conduit length; the saphenous vein was the original conduit for CCBG. Since that report of its 1st applications,12 the method has been used for similar indications by other surgeons.13–15 Accola and Jones16 performed right coronary endarterectomy for proximal anastomosis of vein grafts (CCBG) in a patient with porcelain aorta.
Inadequate length of the in situ RITA to reach the distal RCA limits the use of that vessel. Lack of an arterial conduit of adequate quality and length is a good reason to perform CCBG, which enables revascularization of the distal RCA. We prefer the ITA to the gastroepiploic or the radial artery, because the ITA, as a conduit, is easier to use and less vasospastic. Tixier and associates17 reported performing CCBG with a radial artery graft in a case of completely obstructed RCA; however, Dietl and colleagues18 preferred the gastroepiploic artery as a conduit, due to the high risk of intimal hyperplasia and the uncertain long-term results associated with the radial artery. We also used the gastroepiploic artery for right coronary revascularization in 13 cases; this method was time-consuming and technically challenging. Although we have tried other alternative conduits, we prefer to use the remaining ITA segment for CCBG, because it is easier and saves considerable time. This procedure has the further advantage of sparing a segment of the ITA for other purposes, such as the construction of a new T arterial conduit (the arterial conduit-sparing procedure) and extensive sequential anastomosis.1,19
If calcification of the ascending aorta is severe, CCBG is an alternative technique for complete revascularization.12,15,16 Although none of our patients had a subclavian stenosis or occlusion, CCBG can be performed safely in that circumstance.
In patients at risk of respiratory and sternal morbidity, the CCBG technique enables the use of a single ITA for the revascularization of the RCA.1 In 10 of our patients who carried this risk, we in fact used only the distal part of the LITA. The free RITA (full length) was used as a conduit for CCBG in 4 patients, in order to reach the distal RCA. In the other 34 patients, we used the bilateral ITA, and we performed CCBG to the RCA by means of a remaining ITA segment, from either the LITA or the RITA.
The 1st segments of the RCA are recommended for the proximal implantation of CCBG when the ostium and 1st segments are free of atherosclerosis and adequate in diameter.1,20,21 In our series, we most often performed the proximal anastomosis at the ostium and the 1st segment of the RCA (79.2%). As described by Nishida20 and Biglioli21 and their associates, proximal anastomoses constructed on the coronary artery itself take advantage of the physiologic position of the right coronary ostium. The filling of the graft is assisted by several factors that promote physiologic diastolic coronary artery flow. However, progression of coronary disease at the proximal anastomosis site raises a major concern. Bruschke and co-authors22 followed the anatomic evolution of coronary artery disease in 256 patients who had not been operated upon and found that the proximal and mid-RCA segments had the highest risk of disease progression among RCA segments. Although this study revealed almost no progression at the RCA origin and at the 1st segment (from which the large conal branch arises), it found a high progression rate for the segments beyond the acute marginal branch.22 It has been suggested that CCBG can provide nearly the same flow rate as CABG, and that the proximal RCA has a flow reserve sufficient for this technique.1,21,23,24 Aazami25 has questioned whether the CCBG, when constructed from the right coronary system to the left coronary system (as done by Biglioli's group21), would have this physiologic effect. Aazami proposed that constructing the CCBG from the RCA to the RCA is a more physiologic alternative. Although we performed bypasses from the right system to the right system, a proximal anastomosis to the coronary ostium was not possible in all patients, due to inadequate length of remaining ITA. Nezic and associates26 have stated that proximal anastomoses placed on the right coronary ostium (as performed by Biglioli21 or Nottin1) does not simulate physiologic coronary blood flow, because the double orifice so created impairs natural flow and distribution. Nevertheless, we believe that a normal proximal coronary artery segment is a prerequisite for CCBG.
The early and mid-term results of CCBG are promising. By using methods such as those applied to the revascularization of multiple lesions on the LAD by CCBG (described by Barboso and Rusticali27 and developed by Nezic26,28,29), surgeons can use CCBG for the revascularization of various arteries. Our study may shed yet more light on potential methods.
Coronary–coronary bypass grafting is an alternative technique that, in selected patients, enables the use of both ITAs for extensive myocardial revascularization by means of sequential anastomosis and Y or T grafts. However, to decrease sternal and respiratory morbidity in at-risk patients, such as those with obesity, insulin-dependent diabetes and old age, chronic obstructive pulmonary disease, and fragile sternum, a single ITA (the LITA) can be used for the revascularization of 2 different vessels—the LAD and the RCA.
In consideration of the fact that atherosclerosis is an ongoing disease, surgeons may choose to use the short segment of the ITA for CCBG in patients who display low-grade stenosis of the RCA.
Address for reprints: A. Ali Korkmaz, MD, Validebag Sitesi 25. Blk. D:21 Altunizade-Uskudar, 81020 Istanbul, Turkey. E-mail: moc.liamg@zamkrokaa