Ann Thorac Surg 2005;80:1948-1950
© 2005 The Society of Thoracic Surgeons
How to do it
Multiple Arterial Revascularization Using the Tangential K-Graft Technique
Boris Orlov, MD,
Jacob Gurevitch, MD
*
,
Alexander Kogan, MD,
Victor Rubchevsky, MD,
Amnon Y. Zlotnick, MD,
Dan Aravot, MD
Department of Thoracic and Cardiovascular Surgery, Carmel Medical Center, Technion-Haifa, Israel
Accepted for publication May 7, 2004.
* Address correspondence to Dr Gurevitch, Department of Thoracic and Cardiovascular Surgery, Carmel Medical Center, 7 Michal St, Haifa, Israel (Email: nettag{at}barak-online.net).
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Abstract
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The tangential K graft is a comfortable surgical technique aiming to increase cardiac surgeons' versatility in performing multiple arterial grafting using only two arterial conduits. One end of the free graft—either the right internal thoracic artery (RITA) or the radial artery (RA)—is attached to a marginal circumflex branch. Its other end is anastomosed end to side to a diagonal branch. After the left internal thoracic artery (LITA) is attached to the left anterior descending coronary artery, a wide-open side-to-side LITA to free RITA or RA anastomosis—resembling the letter K—is constructed.
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Introduction
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The use of both the left and free right internal thoracic arteries (ITA) for revascularization of the left anterior descending (LAD) and circumflex coronary arteries has been shown to be superior to the use of one ITA in combination with vein grafts in long-term survival and quality of life, providing freedom from angina and reintervention [1, 2]. Multiple arterial grafting can be achieved by joining either the right ITA or radial artery (RA) to the LITA as a Y graft or T graft [3–5].
However, significant diagonal or intermediate branches are, at times, just off the route of the LITA to the LAD (too lateral), but at the same time too distal and inappropriate for sequential grafting with the free RITA or RA. These circumstances might result in the overlooking of graftable vessels, leading to incomplete myocardial revascularization. Technical error in constructing the T anastomosis can jeopardize the entire revascularization and cause hypoperfusion syndrome [6–8]. At times, the free RITA or RA conduits may be too short, and kink the LITA at the anastomotic site.
The tangential K-graft composite technique (Fig 1) addresses these cases and may provide additional versatility in performing multiple arterial grafting.
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Fig 1. (A) Total arterial revascularization of the left ventricle using the tangential K-grafting technique. The distal end of the free right internal thoracic artery (RITA) is anastomosed end-to-side to a marginal branch of the circumflex coronary artery. Its proximal end is anastomosed end-to-side to a diagonal branch of the left anterior descending coronary artery (LAD). The left internal thoracic artery (LITA) is then used for revascularization of the LAD. Finally, a wide-open side-to-side RITA-LITA anastomosis—the tangential K-graft (resembling the letter K)—is constructed. (LIMA = left internal mammary artery; RIMA = right internal mammary artery.) (B) The tangential K-grafting technique in a quadruple bypass to the left ventricle using only two arterial grafts. Sequential side-to-side anastomoses are constructed parallel to the coronary artery. Gentle curves are made by the free RITA between each anastomosis. The LITA is attached to the LAD, and finally a simple, wide-open, side-to-side RITA-LITA anastomosis is performed.
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Technique
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The ITAs were prepared using the skeletonization technique, with a low-energy cautery blade. Each ITA was mobilized from origin to beyond its bifurcation and examined for adequacy of pulse, size, injury, dissection, and the presence of arteriosclerosis. The RA was dissected at the nondominant arm using the standard technique [2, 4].
After preparation of both grafts (LITA and free RITA or LITA and RA), their distal end was closed with a Hemoclip device (Weck Closure Systems, Research Triangle Park, NC), and they were wrapped in wet soaking gauze with diluted papaverine (50 mg/20 mL Ringer solution). Patients where the RA was in use were routinely treated with nitrates during the operation and for 3 months after surgery (isosorbide dinitrate) to prevent conduit vasospasm. All patients were operated upon on extracorporeal circulation and mild systemic hypothermia (32°C to 34°C). A 13-gauge needle was inserted into the ascending aorta for infusion of cold antegrade blood cardioplegia and for venting.
The distal end of the free graft was anastomosed end to side using 8-0 monofilament sutures. More proximal anastomoses are always constructed parallel to the coronary artery. We no longer use perpendicular or diamond-shaped side-to-side anastomoses because we believe they pose a risk of narrowing. The other end of the free arterial conduit was then anastomosed end to side to a diagonal or intermediate branch. Because native arteries do not run in a perfectly straight course, gentle curves were made in conduits between each anastomosis. The LITA was then used for revascularization of the anterior descending system. Finally, a wide-open side-to-side free RITA or RA LITA anastomosis (resembling to the letter K)—the tangential K graft—was constructed.
From July 2002 to November 2003, 91 consecutive patients underwent multiple arterial grafting using the K-graft technique. A tangential K graft of the RITA to the LITA was used in 78 patients (86%; Fig 2), whereas 13 patients (14%) received a combination of RA to LITA. The average number of distal anastomoses per patient was 3.9. The LITA was used for 96 distal anastomoses, the RITA was used for 183 (2.3 per patient), and RA for 45 distal anastomoses (2.5 per patient). Cross-clamp time was 79 ± 13 minutes, and bypass time was 98 ± 16. No patients died in hospital. One required postoperative intraaortic balloon pump. There were no perioperative myocardial infarctions or strokes. One patient had mediastinitis, and 3 had superficial wound infections. During the follow-up year, no patients had recurrent angina or intervention. Newly released 16-slice multidetector computed tomography scans verified patency in all 7 arbitrary patients studied early postoperatively.
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Fig 2. A 67-year-old man who underwent complete arterial myocardial revascularization with tangential K-graft using right and left internal thoracic arteries. This picture was taken after removal of aortic cross clamp. The left internal thoracic artery emerges from the left subclavian artery and approaches the anterior descending coronary artery. The free right internal thoracic artery is attached to the diagonal branch and to a distal marginal circumflex coronary artery. The two arterial grafts are connected in a tangential K-graft side-to-side fashion.
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Comment
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In view of the excellent long-term function of the ITA, the current trend is to expand the use of arterial grafts in CABG. The T-graft technique entails complete arterial revascularization achieved with two conduits in which the RITA or RA are usually grafted end to side to the in situ LITA and directed to the lateral and posterior aspects of the left ventricle, while the LITA is directed to the anterior surface of the heart [3–5]. Expanded use of this technique by Tector and associates [4], who coined the name, has raised three major concerns, namely, hypoperfusion [2, 4–8], the technical complexity of the procedure, and sternal complication [9].
Skeletonization of the ITAs may reduce the incidence of sternal wound infection, apparently by preserving the collateral blood flow to the sternum, thus enhancing sternal wound healing [2, 9].
Perioperative hypoperfusion leading to ischemia, infarction, low output states, or even profound hypotension has occurred in 1% to 2% of the patients undergoing T-graft surgery [2–5]. It is evident to us that the etiology lies in injury to the conduit during harvest, technical errors in the anastomosis, linear tension on the conduit, angulation at anastomotic site, and unresolved harvest spasm [7].
The tangential K-graft composite technique (Fig 1) was first constructed to solve a technical problem during surgery, wherein the second free graft (the RITA) was too short to sequentially anastomose a diagonal branch and reach the LITA to create the end-to-side "T graft" without creating considerable tension or kink on the LITA. This new composition provided an inventive, elegant, and uncomplicated solution (Fig 2) for sparing free conduit length. During our accumulating experience with this technique, we have noticed several potential advantages of the K over the T graft, such as the following: (1) A more open, easier to construct, side-to-side longitudinal anastomosis is created between the conduits, in contrast with the relatively narrow end-to-side T-shaped anastomosis; at least one experimental study has demonstrated that the development of intimal hyperplasia was much milder in 45-degree (as in the K-graft anastomoses) than 90-degrees (as in the T graft) anastomosed vessels, correlating with low velocity of flowing blood and the resultant low shear stresses acting on the vessel wall [10]. (2) The diagonal is anastomosed end-to-side using the free conduit, which is technically easier than any side-to-side either longitudinal or diamond-shaped anastomosis. (3) Any significant diagonal or intermediate branch can now be easily grafted, even distally, without any compromise, even if the anastomotic site is not on the route of either the free RITA or the LITA without the need of additional conduit.
All the suggested theoretical advantages of the K-graft technique need to be tested in future intraoperative or postoperative flow measurements in the conduits and early and late postoperative angiograms. Although in the vast majority of patients undergoing multiple arterial grafting, T or Y grafting is still used in our service, this new K-grafting technique is being used when appropriate as an auxiliary convenient method of performing multiple grafting to the left ventricle using only two arterial conduits.
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References
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- Endo M, Nishida H, Tomizawa Y, Kasanuki H. Benefit of bilateral over single internal mammary artery grafts for multiple coronary artery bypass grafting Circulation 2001;104:2164-2170.[Abstract/Free Full Text]
- Wendler O, Hennen B, Demertzis S, et al. Complete arterial revascularization in multivessel coronary artery disease with 2 conduits (skeletonized grafts and T grafts) Circulation 2000;102(Suppl 3):79-83.
- Tector AJ, Amundsen S, Schmahl TM, Kress DC, Peter M. Total revascularization with T grafts Ann Thorac Surg 1994;57:33-39.[Abstract]
- Calafiore AM, Di Mauro M, D'Alessandro S, et al. Revascularization of the lateral walllong-term angiographic and clinical results of radial artery versus right internal thoracic artery grafting. J Thorac Cardiovasc Surg 2002;123:225-231.[Abstract/Free Full Text]
- Sakaguchi G, Tadamura E, Ohnaka M, Tambara K, Nishimura K, Komeda M. Composite arterial Y graft has less coronary flow reserve than independent grafts Ann Thorac Surg 2002;74:493-496.[Abstract/Free Full Text]
- Jones EL, Lattouf OM, Weintraub WS. Catastrophic consequences of internal mammary artery hypoperfusion J Thorac Cardiovasc Surg 1989;98:902-907.[Abstract]
- Gaudino M, Trani C, Luciani N, Alessandrini F, Possati G. The internal mammary artery malperfusion syndromelate angiographic verification. Ann Thorac Surg 1997;63:1257-1261.[Abstract/Free Full Text]
- Carrel T, Kujawski T, Zund G, et al. The internal mammary artery malperfusion syndromeincidence, treatment and angiographic verification. Eur J Cardiothorac Surg 1995;9:190-197.[Abstract]
- Calafiore AM, Vitolla G, Iaco AL, et al. Bilateral internal mammary artery graftingmidterm results of pedicled versus skeletonized conduits. Ann Thorac Surg 1999;67:1637-1642.[Abstract/Free Full Text]
- Ishibashi H, Sunamura M, Karino T. Flow patterns and preferred sites of intimal thickening in end-to-end anastomosed vessels Surgery 1995;117:409-420.[Medline]
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Abstract
Introduction
