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Department of Cardiovascular Surgery, Aichi Cardiovascular and Respiratory Center, Aichi, Japan
Accepted for publication October 12, 2007.
* Address correspondence to Dr Eda, Department of Cardiovascular Surgery, Aichi Cardiovascular and Respiratory Center, 2135 Kariyasuka, Yamato Ichinomiya, Aichi, 491-0934, Japan (Email: cdb57810{at}hkg.odn.ne.jp).
| Abstract |
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Methods: Between January 1997 and April 2001, 57 patients underwent coronary artery grafting with a free GEA using our method. A total of 169 distal anastomoses (average 2.96) were constructed. The free GEA grafts were anastomosed to the main right coronary artery in 26 patients, right coronary artery branch in 27, left anterior descending artery in 1 patient, high lateral branch in 2 patients, and circumflex branch in 2. The mean clinical follow-up is 77 months (range, 35 to 110) in 57 cases, and the angiographic follow-up averages 77 months (range, 37 to 110) in 46 cases.
Results: There was no cardiac death, and all patients were in Canadian Cardiovascular Society class II or less. The mean 77-month patency rate of the free GEA in our method was 95.7%. The patency rates of internal thoracic artery, radial artery, and saphenous vein graft in the same period were respectively 93.2%, 100%, and 81.3%.
Conclusions: Free GEA grafting with venous drainage for myocardial revascularization provided excellent long-term performance.
| Introduction |
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We hypothesize that the main cause of free GEA spasm is graft damage caused by an interruption of venous drainage from the graft. To overcome this problem, we anastomosed the accompanied gastroepiploic vein (GEV) to the right atrial appendage simultaneously with the free GEA for venous drainage. Excellent early angiographic results of free GEA grafting with venous drainage (en bloc free GEA grafting) have already been published [20]. The present study evaluates the long-term clinical and angiographic results of en bloc free GEA grafting for myocardial revascularization.
| Material and Methods |
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Study Patients
We examined 57 cases of bypass operation in which en bloc free GEA grafting had been used between January 1997 and April 2001. The patients were 49 men and 8 women. Their age at the operation ranged from 37 to 74 years, with a mean of 58 years. Two patients were in Canadian Cardiovascular Society class IV, 21 in class III, 29 in class II, and 5 in class I. No patients had undergone previous surgical myocardial revascularization. Forty-seven patients had triple-vessel disease, and 10 patients had double-vessel disease. Fifteen patients had significant stenosis of the left main trunk. The average ejection fraction according to echocardiography was 61.3% (range, 45% to 75%). Other preoperative characteristics are listed in Table 1. Concomitant procedure is the Dor operation in 1 case.
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Grafts and Target Vessels
A total of 169 distal anastomosis (average 2.96; range, 2 to 5 per patient) were constructed: 58 with the en bloc free GEA graft, 54 with the internal thoracic artery, 16 with the radial artery, and 41 with a saphenous vein graft. The mean number of coronary arteries bypassed by arterial graft was 2.03 (range, 1 to 3). The target vessels of en bloc free GEA grafting were the main right coronary artery in 25, the right coronary branch in 26, the circumflex branch in 2, the left anterior descending artery in 1, the high lateral branch in 2, and the sequential bypass of the main right coronary artery to right coronary artery branch in 1. Table 2
lists the coronary findings and operative data.
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| Comment |
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Several authors have reported the use of the right GEA as a free graft [2, 15–20]. Compared with the in situ graft, the advantages of a free GEA graft are as follows: (1) the flow through a free GEA is larger than that through an in situ GEA; (2) it is easily handled in the pericardial cavity; (3) the window and hazardous maneuvers through the diaphragm are avoided; (4) greater chances exist for myocardial revascularization as all the coronary vessels can be reached; (5) it is suitable for sequential anastomosis; (6) any risk of damaging the graft in future upper abdominal operations is averted; and (7) the distal anastomosis site is the large caliber portion, because the more proximal portion of the GEA is used to bypass.
However, some reports indicate that free GEA grafts are prone to vasospasm, and the early patency rate of the free GEA grafts was lower than that of in situ grafts [2, 18–19]. The long-term patency rate of traditional free GEA grafting (without venous drainage) is unknown.
Cate and colleagues [19] concluded that the GEA, although similar to the internal mammary artery in size and flow characteristics, is different both histologically and physiologically. When used as a free graft, the GEA is very vasospastic, which may influence its long-term patency. When it is necessary to use the GEA as a conduit, it may be preferable to use it in situ rather than as a free graft. Mills and Everson [18] reported that 3 of 10 free GEA grafts showed major vasospasm at early postoperative cardiac catheterization. They also reported edema in the pedicle when the GEV was ligated during harvest of the GEA graft.
We also have had 3 patients who underwent surgical myocardial revascularization with the traditional use of a free GEA. In 1 case, the sternum closure was disturbed by the swollen periarterial tissues, mainly caused by blood congestion. In another case, troublesome bleeding occurred when the graft was unclamped, and control of bleeding jeopardized the graft. In these 2 cases, postoperative angiography revealed the grafts to be occluded. Therefore, we suggest that the cause of the free GEA spasm is graft damage caused by an interruption of venous drainage from the graft. The major complications with a free GEA were swelling of the graft and bleeding from it, which were caused by a lack of venous drainage.
We tested the harvested grafts before transplantation in 10 cases in this study. Heparinized blood was injected into GEA in the graft at a high pressure (100 mm Hg) to detect bleeding from the side branches, and simultaneously, pressure change in the GEV was recorded. In all 10 grafts, venous pressure increased from 0 mm Hg to more than 40 mm Hg within 2 minutes, and swelling of the grafts was observed. Then blood flow from the open end of the GEV was measured, which indicated a rate of 2.0 to 9.5 mL/min. The results of this clinical study suggest that free GEA grafting in the aortocoronary position without venous drainage undoubtedly causes expansion of the GEV and swelling of the graft pedicle.
To overcome this problem, we began to anastomose the accompanied gastroepiploic vein to the right atrial appendage for drainage simultaneously with the GEA grafting (en bloc free GEA grafting). Because omentum is a living tissue that contains a lot of lymphatic, venous, and arterial vessels, traditional free GEA grafting causes graft swelling. The Mills and Everson study [18] reported edema in the pedicle when the GEV was ligated during harvest of the GEA graft. On the other hand, free ITA and radial artery grafts rarely include edema in the pedicle. This is the reason why only free GEA grafting requires venous drainage. Furthermore, when it is dilated, the GEV has an adequate caliber for anastomosis, but the internal thoracic vein and the radial vein are too small for anastomosis.
An excellent early result of en bloc free GEA grafting has been reported in our previous study [20]. We here report the long-term clinical and angiographic results. The average 6.4-year patency rate of the en bloc free GEA is 95.7%, which is superior to the results of the in situ GEA grafting referred to above.
Cate and colleagues [19] reported that, when used as a conventional free graft, the GEA is very vasospastic, which may influence its long-term patency. In our method, in contrast, vasospasm of the en bloc free GEA grafts was never seen. The difference in the results between conventional free GEA grafting and en bloc free GEA grafting is due to the presence of venous drainage.
The en bloc free GEA grafting is a transplantation of the living omentum; this graft is not only an arterial conduit, but also a part of the living organ. In the present study group, the angiography revealed patent grafted GEV in 2 patients at 72 months after surgery. We further ensured restoration of the patency of the en bloc free GEA graft; the patient had multiple coronary artery bypass grafts put in place. One graft was the en bloc free GEA graft to the distal right coronary. At cardiac angiography 1 month later, the graft was patent, but at coronary angiogram a year later, the graft had a string sign; 8 years later the graft was widely patent with progression of native coronary artery stenosis [21]. This reversibility of the en bloc free GEA and patent grafted GEV suggests the continued life of the transplanted graft.
In conclusion, en bloc free GEA grafting can prevent GEA spasm, improving long-term patency. We consider the en bloc free GEA to be the most reliable and useful arterial graft material.
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