Asian Cardiovasc Thorac Ann 1999;7:252-253
© 1999 Asia Publishing EXchange Pte Ltd
Extrafascial Harvesting of Radial Artery for Coronary Artery Grafting
Gutti Ramasubrahmanyam, MCh,
Kati Venkata Ramana Raju, MCh,
Goli Nagasaina Rao, MCh,
Neeladri Varma N V, MCh,
Kummara Chinna Venkateswara Rao, MCh,
Guntaboina Usha Rani, MCh,
Dasari Prasada Rao, MCh
Care Hospital, The Heart Institute
Hyderabad, India
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For reprint information contact: Gutti Ramasubrahmanyam, MCh Tel: 91 40 473 5465 Fax: 91 40 474 5110 Care Hospital, The Heart Institute, Exhibition Road, Nampally, Hyderabad 500001, India.
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Abstract
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A modified method of harvesting radial artery conduit for use in coronary bypass surgery is described. Extrafascial harvesting reduces the incidence of conduit spasm during harvest and after grafting. The muscular branches are of adequate size to be ligated with silk without using clips. Whether there is any difference in long-term graft patency rates between extrafascial and intrafascial harvesting needs to be evaluated.
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Introduction
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Following a revival in the use of the radial artery as a conduit in coronary artery bypass grafting surgery, it is commonly employed in many centers with better long-term results. Classically, the radial artery is harvested by opening the fascial sheath along with the venae comitantes and surrounding fat.1 With this technique, the radial artery may go into spasm during harvesting, intraoperatively, or in the immediate postoperative period, leading to ischemia-related problems. To avoid this, a technique of extrafascial harvest was devised.
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Technique
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Skin incision and initial exposure of the radial artery is carried out as described by Reyes and colleagues.1 Once the radial artery groove is exposed, the fascia covering the radial artery is left unopened and two parallel incisions are made 3 mm from the radial artery on either side. Extrafascial dissection is then carried out. Dissection begins in the middle of the forearm by slowly lifting up the pedicle from the muscle underneath, muscular branches that come across are clipped or ligated with 4/0 braided silk. The underlying muscles from which the fascia has to be separated are the flexor pollicis longus and the flexor digitorum superficialis. At the proximal end, the radial pedicle brachioradialis and flexor carpi radialis are retracted laterally and the dissection is completed. During dissection, the superficial radial nerve on the radial aspect of the pedicle is protected from thermal injury by gentle traction of the pedicle towards the ulna. The graft is then divided after systemic heparinization and before going on cardiopulmonary bypass. We use a continuous intravenous infusion of diltiazem hydrochloride in a dose of 0.5 µg•kg–1•min–1. Inspection of the radial artery conduit is performed with gentle hydrostatic dilatation using a solution of blood and papaverine (60 mg papaverine in 50 mL blood). After inspection, the conduit is wrapped in saline-soaked gauze. Radial artery conduits prepared by the extrafascial and intrafascial techniques are shown in Figures 1 and 2
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Figure 1. Harvested radial artery conduit using the extrafascial technique (branches are ligated with silk).
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Figure 2. Harvested radial artery conduit using the intrafascial technique (branches are ligated with clips).
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Discussion
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We have used radial artery conduit in coronary bypass graft surgery in more than 1200 cases since 1994. Our initial technique of radial artery harvesting was similar to that described by Reyes and colleagues1 and minimal modifications were reported earlier.2 An intrafascial radial artery conduit is bare and more likely to go into spasm. The phenomenon of radial artery spasm is well-known and it can be reduced by the use of calcium channel blockers intraoperatively and postoperatively. In addition to the inherent nature of this conduit, the technique of harvesting and preparation can affect its susceptibility to spasm. An extrafascial radial artery conduit is one that is harvested along with the covering flexor fascia. There are several advantages of the extrafascial technique described here. The major advantage is that the incidence of spasm is reduced to a minimum. By using silk instead of clips to ligate the muscular branches, the cost is reduced and the minimal fibrosis at the site of a silk ligature does not affect the actual radial artery conduit as the ligature is outside the fascia. The harvesting time for the extrafascial conduit is less than in the intrafascial technique as the number of radial artery branches that come across are fewer.
It is well-known that increased wall tension stimulates proliferation of vascular smooth muscle cells after implantation of vein grafts and animal experiments have shown that use of external vessel supports with coronary conduits results in a marked reduction of medial and intimal thickening.3 In this technique, the radial artery is harvested along with covering fascia as an external support to minimize intimal and medial thickening in the long term. Even if low diathermy cautery is used during dissection, the risk of thermal injury is less. However, the difference in graft patency rates between the two techniques needs to be evaluated. One possible dis-advantage is that occasionally the radial artery may be found after dissection to be too small and not suitable for grafting but this can be avoided by preoperative Doppler flow evaluation. As the extrafascial radial artery is a free graft and covered externally by supporting fascia, thrombotic occlusion of the venae comitantes does not occur as they are collapsed and no blood remains, which in turn helps to reduce fibrosis around the radial artery.
We have used this technique in 150 cases and did not observe any complications in the harvested forearm related to this technique. There have been no incidences of perioperative myocardial infarction in the territory of the radial artery graft. While preparing the end of the conduit for both proximal and distal anastomosis, an initial oblique cut should extend only to three-quarters of the circum-ference to avoid slipping of the artery into the fascial sheath, making it difficult to hold. Later, a vertical cut is used to adjust the length. We routinely perform proximal anastomosis to the aorta directly and occasionally as a T graft to the internal thoracic artery. During sequential anastomosis at the proposed site, the fascia that covers the radial artery is incised and later a long-axis arteriotomy is performed. The rest of the procedure does not differ from the standard technique.
We prefer this method of harvesting because it provides a better quality of conduit which is less prone to spasm related to mechanical injury. The patency rate with this technique is currently being evaluated and will be reported later.
Presented at the 45th Annual Conference of the Indian Association of Cardiovascular and Thoracic Surgeons, Bhopal, India, February 25–28, 1999.
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References
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Reyes AT, Frame R, Broadman RF. Technique for harvesting the radial artery as a coronary bypass graft. Ann Thorac Surg 1992;54:652–60.[Abstract]
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Ramasubrahmanyam G, Venkateswara Rao KC, Usha Rani G, Madhusudhana Rao I, Prasada Rao D. Radial artery in coronary bypass grafting. Ann Thorac Surg 1996;61:771–7.[Free Full Text]
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Angelini GD, Izzat MB, Bryan AJ, Newby AC. External stenting reduces early medial and neointimal thickening in a pig model of arteriovenous bypass grafting. J Thorac Cardiovasc Sug 1996;112:79–84.[Abstract/Free Full Text]
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Abstract
Introduction
