Ann Thorac Surg 2006;82:1131-1133
© 2006 The Society of Thoracic Surgeons
How to do it
Preoperative Evaluation of the Right Gastroepiploic Artery Using Abdominal Ultrasonography
Masahito Minakawa, MD, PhDa,
Ikuo Fukuda, MD, PhDa,*,
Mitsuyoshi Wada, MD, PhDb,
Ji Kaiqiang, MDa,
Kazuyuki Daitoku, MD, PhDa,
Kazuo Itoh, MD, PhDa,
Kozo Fukui, MD, PhDa
a Department of Surgery I, Hirosaki University School of Medicine, Hirosaki
b Department of Radiology, Tsukuba Medical Center, Tsukuba, Japan
Accepted for publication September 6, 2005.
* Address correspondence to Dr Fukuda, Department of Surgery I, Hirosaki University School of Medicine, 5-Zaifucho, Hirosaki, 036-8562, Japan (Email: ikuofuku{at}cc.hirosaki-u.ac.jp).
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Abstract
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Preoperative evaluation of the right gastroepiploic artery was performed by abdominal ultrasonography to determine whether the graft was adequate for coronary artery bypass. The gastroepiploic artery was used when the graft diameter was greater than 2 mm with pulsatile flow. Postoperative angiography revealed the gastroepiploic artery dominant, and the graft diameter measured by angiography was almost the same size as that of abdominal ultrasonography.
The right gastroepiploic artery (GEA) has been an important arterial graft in coronary revascularization, and the opportunities to use this artery as the in situ or free graft have been increasing lately. However we sometimes experience cases in which the GEA is not suitable for the graft because the diameter is not large enough to anastomose or the blood flow is poor. The aim of this study was to evaluate the graftability of the GEA using abdominal ultrasonography preoperatively.
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Technique
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Between October 2002 and June 2005, 27 patients consisting of 22 males and 5 females underwent abdominal ultrasonographic evaluation of the GEA. Measurements were performed using a 3.5-MHz transducer equipped with an echo camera. First the echo probe with a B-mode was set in the upper median line of the abdomen. Then by identifying the left lobe of the liver and the stomach wall that is observable as three layers, we could find the GEA along with the gastroepiploic vein at the ventral or lower side nearby the stomach (Fig 1A). The diameter of the GEA was measured including the vessel wall that was observed in high echoic intensity. Using a Color Doppler mode, we had confirmed the pulsatile blood flow of the GEA in both short axis and longitudinal section (Fig 1B). We decided on the following criteria for using the GEA: (1) the diameter of the GEA was greater than 2 mm, (2) coronary stenosis of the target vessel was greater than 90%, and (3) in the cases in which the coronary stenosis ranged from 75% to 90%, the GEA was anastomosed more distally to the coronary artery where the diameter of the coronary artery was smaller than the GEA.
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Fig 1. (A) From the upper median view of the abdomen, the gastroepiploic artery (GEA) was observed nearby the stomach along with the gastroepiploic vein (GEV). The diameter of the GEA was measured including the vessel wall. (B) Longitudinal (left figure) and short axis (right figure) view of the GEA in color Doppler mode to confirm pulsatile blood flow.
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The postoperative evaluation of the GEA was performed by angiography through the 4-French catheter inserted into the gastroduodenal artery through the femoral artery approach. The luminal diameter of the GEA within the pericardial cavity was measured on the angiographic image and was compared statistically with the diameter measured by abdominal sonography.
Statistical analysis was performed with StatView software for Windows, version 5.0 (Abacus Concepts, Inc, Berkley, CA). Simple regression analysis was performed to assess the correlation between the diameter measured by angiography and abdominal sonography. All results were expressed as the mean ± standard deviation. Differences were considered significant at p < 0.05.
The diameters of the GEAs measured by sonography ranged from 1.5 to 3.6 mm (mean 2.70 ± 0.52 SD mm). Gastroepiploic arteries were not used in five cases because they did not fulfill our indications. In the other 22 cases we found intraoperatively that the GEAs were large enough to anastomose with good arterial pulsations and flow. Postoperative angiographies of the GEAs were performed in 20 of 22 cases, and the GEAs were all patent in the early postoperative stage. Postoperative diameters of the GEAs were measured by angiography in 14 cases. There was a significant positive correlation between the diameters measured by preoperative abdominal ultrasonography and postoperative angiography (p < 0.0001) (Fig 2).
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Fig 2. Correlation between the diameters of the gastroepiploic artery measured by abdominal sonography and angiography by cardiac catheterization. Correlation coefficient was calculated as 0.957 and the p value was <0.0001.
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Comment
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It has been reported that the 5-year patency of the GEA graft was from 80.5% to 84.4%, whereas that of the internal thoracic artery was 97.0% [1, 2]. Several reasons for the lower patency rate of the GEA than the internal thoracic artery have been considered. First because the GEA enriches vascular smooth muscle cells in the media and has defects in the continuity of internal elastic lamina, an increasing propensity for atherosclerosis has been suggested as compared with the internal thoracic artery [3]. In addition, the GEA becomes easily spastic when it is harvested or in the case of acute heart failure. Second because the diameter of the GEA is small in some individuals, there is a possibility that the blood supply from the GEA would be insufficient to provide adequate coronary blood flow through the anastomotic region. Several studies about the factors influencing the quality of the anastomosed GEA have been reported. In the theoretical model of coronary artery bypass grafting (CABG) in which the in situ GEA was anastomosed to the right coronary artery, it is reported that the dominant flow from the anastomosed GEA is determined by both the degree of the proximal stenosis of the right coronary artery and the inner diameter of the GEA [4]. If the inner diameter of the GEA is 0.5 mm larger than that of the right coronary artery, the GEA can be applied despite a moderate stenosis in the right coronary artery [4]. In the clinical study that evaluated coronary flow pattern after CABG using the GEA by postoperative angiography, dominant flow from the GEA was reported to be dependent on the following three factors: (1) bypass grafting to the old myocardial infarction area, (2) the degree of proximal stenosis more than 90%, and (3) bypass grafting to the distal coronary artery with stenosis more distal in location [5]. Furthermore, in the postoperative echocardiography evaluation of the patients who underwent CABG using the GEA under dobutamine stress, the luminal diameter of the GEA of greater than 2.6 mm by postoperative angiography had the highest sensitivity and specificity for a nonischemic change in the GEA grafted region [6]. Other investigators had recommended using the GEA when the luminal diameter was greater than 2 mm by preoperative angiography in cases requiring sequential grafting of the GEA. Therefore, whether or not to use the evaluated GEA was decided based on the graft diameter and the location and degree of stenosis of the target coronary artery as previously mentioned.
Several evaluations of the GEA have been previously described to assess the graftability in CABG. As a preoperative evaluation, angiography by catheter inserted into the GEA is the most reliable method, but it is an invasive technique and requires contrast agent. Recent development of computed-tomographic scanning in high resolution and three-directional construction image has contributed to the accurate assessment of small vessels. The efficacy of computed tomographic angiography assessment of the GEA has been reported [7], but this examination also requires contrast agent. We believe that the ultrasonographic evaluation of the GEA is beneficial because it is low in cost, noninvasive, and easy to perform. In addition, we can perform precise evaluation including the measurement of diameter and pulsatile blood flow of the GEA without creating spasm, which thereby helps planning the operative strategy in CABG. In our cases, the diameter of the GEA was almost the same size between that measured by postoperative angiography and abdominal ultrasonography.
The limitation of this method is that we cannot assess the area from celiac artery to gastroduodenal artery. Then there is a possibility that stenosis or obstruction may be created at that area. Therefore it is important to assure not only the diameter but also the pulsatile flow by color Doppler mode.
We conclude that the ultrasonographic evaluation of the GEA is low-cost, noninvasive, and easy to perform, and it can help to decide the optimal strategy in CABG.
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References
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