MMCTS
(March 15, 2006). doi:10.1510/mmcts.2004.000794
Copyright © 2006 European Association for Cardio-thoracic Surgery
Procedure
Use of the inferior epigastric artery for CABG
Giovanni Teodori1,2,*,
Philippe-Primo Caimmi1,
Thomas Toscano1 and
Massimo Bernardi1
1 Department of Cardiovascular Disease, Center of Cardiac Surgery, Ospedale Maggiore della Carità, University of East Piedmont, Novara, Italy
2 Formerly at the Department of Cardiac Surgery, University of Chieti, Chieti, Italy
* Corresponding author: * Tel.: +39-321-3733522; fax: +39-321-3733526. E-mail: gteodor{at}tin.it
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Summary
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Presentation of the inferior epigastric artery as conduit for coronary artery bypass grafting (CABG): harvesting, use and results.
Key Words: Arterial conduit • Coronary artery bypass grafting • Inferior epigastric artery
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Introduction
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Despite inferior epigastric artery (IEA) being introduced into clinical practice by Puig et al. in the 1980s, the experience is limited in comparison with other arterial conduits [1]. Furthermore, most of the series reported in literature are not comparable because of significant differences in surgical techniques: length of the IEA graft (6–12 cm); direct anastomosis to the aorta; different kinds of composite grafts; and site of the coronary anastomosis [2,3,4,5]. Since Calafiore et al. have championed the use of short segment (4–6 cm) of the IEA as Y-graft from another arterial conduit, this graft became more popular [6,7]. Harvest of a short segment is more easily accomplished, and the strategy of the operation can be planned without waiting for checking out the IEA's adequate length. Additionally, patency for the Y-graft is significantly better than aortic direct anastomosis. Generally only one IEA is harvested but it is possible to use bilateral IEAs [8,9,10,11,12,13].
Anatomy
That part of epigastric artery that is sited under the umbilicus is generally called the IEA. The origin of the epigastric may take place from any part of the external iliac between Poupart's ligament and two inches and a half above it; or it may arise below this ligament, from the femoral or from the deep femoral. After its origin, it descends to reach Poupart's ligament and then ascends obliquely inwards between the peritoneum and transversalis fascia (Schematic 1) to the margin of the sheath of the rectus muscle, lying behind the inguinal canal, to the inner side of the internal abdominal ring, and immediately above the femoral ring. Sometimes the epigastric arises from the obturator artery, the latter vessel being furnished by the internal iliac, or the epigastric may be formed by two branches, one derived from the external iliac, the other from the internal iliac (Schematic 2). Then it perforates the sheath near its lower third, it runs vertically upwards behind the rectus, to which it is distributed and it divides into numerous branches which anastomose above the umbilicus with the terminal branches of the internal thoracic artery (ITA) and inferior intertercostal arteries. The portion of epigastric artery above the umbilicus may be recognized as the upper epigastric artery. The IEA is accompanied by two veins, which usually unite into a single trunk before their termination in the external iliac vein [14,15]. The pathological or atherosclerotic thickenings in this artery are not very common: about 28% of IEAs. The intimal hyperplasia is significantly greater in the first segment of the inferior epigastric artery [16]. The histochemistry demonstrated that the extracellular matrix is rich in highly sulphated acid mucopolysaccharides. Internal elastic lamina of the IEA showed good development equivalent to the ITA [17]. Tunica media of the IEA is poor in elastic fibers and rich in smooth muscle cells compared with the ITA. The intima of IEA is less thin than ITA but it presents less fenestrations than ITA and the combined thickness of media and intima is lower than ITA (0.2 mm vs. 0.3 mm). Contractility, endothelium-independent relaxation, and receptor-mediated endothelium-dependent relaxation are similar in the inferior epigastric artery and the ITA. However, the endothelium of this arterial graft has less ability to respond to the non-receptor-mediated endothelium-derived relaxing factor stimulant. The influence of this difference on the prevalence of atherosclerosis and long-term patency rate in the inferior epigastric artery remains to be studied. The paucity of fenestration in the internal elastic lamina, no medial calcification, the absence of foam cells and the absence of intimal smooth muscle cells suggest the IEA to be a good conduit applicable for CABG because of the low susceptibility to thickening of its intima, low risk of ischemic necrosis of the free graft and the good flow compliance [18,19,20,21,22].
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Surgical technique
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Harvesting and managing
In patients afflicted by arterial pathologies of lower limbs, harvesting of IEA and ITA should be performed to the opposite side of the sick limb, in order to protect its vascularization [23]. Harvesting can be accomplished usually with an incision at the lateral border of the rectus sheath with a lateral approach to the artery (Schematic 3) (Videos 1,2,3), or with a paramedian incision approaching the IEA from the medial side, or with a middleline incision from the umbilicus to symphysis pubis which allows access to both conduits. After it reaches the rectus muscle, the IEA lies posterior to the muscle (70% of cases) (Video 3) but it may divide into two smaller but equal branches (15% of cases), one of which enters the muscle and one of which lies posterior to the muscle, or the non-divided artery may enter the muscle (15% of cases), which makes the dissection exceedingly difficult (Schematic 4) [15].
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Schematic 3 Transverse section of the abdomen, relationship inferior epigastric artery – rectus muscle.
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Video 1 Paramedian infraumbilical incision.
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Video 2 Opening of the anterior sheath of the rectus muscle.
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Video 3 Medially retraction of the rectus muscle.
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With an extensive dissection of the IEA, from its origin to its termination, it is possible to harvest IEA grafts whose lengths are up to 19 cm, but because atherosclerotic disease often involves the proximal part of the IEA close to the iliac artery, it is preferable to harvest the following 10 cm only (Videos 4 and 5).
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Video 4 Dissection of the IEA with its two satellite veins and surrounding fat.
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Video 5 Ligation with clips (Ligaclip Extra LT100 – MMCTSLink 90) and division of collateral branches of the pedicled IEA.
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After dissection, the IEA is forcefully sprayed with a solution of papaverine (1 mg/1 ml) and wrapped with gauze patches soaked with the same solution. The IEA is only divided and explanted after total heparinization (3 mg heparin/kg body weight) (Videos 6 and 7).
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Video 6 After total heparinization (3 mg heparin/kg body weight) the IEA is divided and explanted.
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Video 7 Ligation of proximal and distal branches.
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The distal end of the IEA is opened longitudinally and intubated with an olive-tipped cannula. The IEA is flushed with a solution of warm blood of the patient added with papaverine (1 mg/1 ml) (Video 8).
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Video 8 The distal end of the IEA is opened longitudinally and intubated with an olive-tipped cannula. The IEA is flushed with a solution of warm blood of the patient added with papaverine (1 mg/1 ml) and clipped.
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Afterwards, the IEA is preserved in this medium at room temperature until it is grafted. Harvesting of the IEA takes about 15 min, but can be performed simultaneously with ITA harvesting. The incision is not closed until the heparin is reversed with protamine.
Surgical indications
The IEA, like the gastroepiploic and radial arteries, is prevalently a muscular graft [20].
A low-flow situation as a mild stenosis or higher coronary resistances causes a size reduction of the IEA up to complete occlusion. Hence, the IEA should be grafted to completely occluded or severely stenosed vessels, with low coronary resistances (high-flow situation). The use of the IEA is mostly accepted as a short segment (4 to 6 cm) Y-graft from another arterial conduit to graft a diagonal or a marginal branch, or to elongate another conduit (mainly for the RITA) to reach distal anastomotical sites, such as posterodescendent or posterolateral branches. In particular elongation of LITA with IEA seems a very satisfying option for LAST operation [9,10,11,12]. In fact, in the anterior minithoracotomy generally LITA is not completely harvested and it cannot reach very laterally positioned LAD.
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Results
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We report here the long-term clinical results of the University of Chieti. From September 1991 to December 2001, 163 patients underwent isolated myocardial revascularization grafting of the inferior epigastric artery. Follow up ranged from 1.6 to 11.2 years (mean 7.9±2.5). We evaluated freedom from AMI (acute myocardial infarction), AMI on grafted area, redo/percutaneous coronary angioplasty (PTCA), redo/PTCA on grafted area (Graphs 1,2,3,4). Freedom at 96 months from AMI or redo/PTCA on area that was grafted by IEA was respectively, 93% and 99.3%. Although most significant series from literature of IEA as Y-graft do not present follow up longer than the University of Chieti, their results show similar trends [21,22,23,24]. Only Donatelli and co-workers report the patency rate of IEA significantly lower than ITA [25].
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Discussion
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In the era of totally arterial CABG, surgeons ask for more arterial conduit but the choice of the best conduit needs some clinical evaluation. In fact, the use of the gastroepiploic artery is limited to right coronary artery grafting only; the radial artery is only suitable as free graft, the RITA may be not long enough to graft left sided coronary arteries. In addition, illnesses of the stomach exclude the use of gastroepiploic artery, diabetes does not suggest the use of bilateral ITA, illnesses of the ulnar artery or the superficial palmar arch (the continuation of the ulnar artery) represent a contraindication for the use of the radial artery. After these arguments, the use of IEA for CABG appears to be not neglected any more. In fact, despite of the exiguity of its length, the use of the IEA for ITA-IEA Y-shaped graft or for elongation of ITAs, allows the maximal desfruitment of ITAs for CABG.
Anatomic studies show low susceptibility to thickening of IEA intima and its good flow compliance. The harvesting of the IEA is not invasive, fast and it may be combined with ITAs harvesting without elongation of the time-course of the operation.
Finally, the late follow up, in particular freedom from AMI on grafted area (93.0±2.4 at 96 months) and redo/PTCA on grafted area (99.3±0.7 at 96 months) encourage us to continue in the use of this conduit.
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References
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Summary
Introduction
