Ann Thorac Surg 2003;75:1335-1336
© 2003 The Society of Thoracic Surgeons
How to do it
Extending the in situ right internal mammary artery graft with retrocaval positioning
Roberto Battellini, MD*a,
Michael A. Borger, MD, PhDa,
Carlos Climente, MDb,
Friedrich W. Mohr, MD, PhDa
a Clinic for Heart Surgery, Heart Center, University of Leipzig, Leipzig, Germany
b Hospital Privado de Comunidad, Mar del Plata, Argentina
Accepted for publication September 6, 2002.
* Address reprint requests to Dr Battellini, Heart Center, Clinic for Heart Surgery, University of Leipzig, Strumpellstrasse 39, 04289 Leipzig, Germany
e-mail: battr{at}medizin.uni-leipzig.de
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Abstract
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Bilateral internal mammary artery grafting is associated with improved long-term patient outcomes. In situ right internal mammary artery grafting of the obtuse marginal artery, through the transverse sinus, is often limited by conduit length. We describe the technique of retrocaval positioning of the right internal mammary artery graft to extend its functional length for grafting of the circumflex territory. With careful surgical technique, this procedure can be performed safely during routine coronary bypass operations.
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Introduction
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Bilateral internal mammary artery (IMA) grafting is associated with improved long-term patient outcomes after coronary bypass surgery. Previous studies have demonstrated that patients who receive bilateral IMA grafts have better long-term survival, decreased myocardial infarction rates, and decreased revascularization rates than patients who receive a single IMA [1–3].
The in situ method of IMA grafting may have superior patency rates compared with free IMA grafts, and is often considered the gold standard for arterial conduits [4]. A common technique for bilateral IMA grafting is to use the left IMA (LIMA) to bypass the left anterior descending (LAD) coronary and the right IMA (RIMA) to bypass an obtuse marginal branch of the circumflex artery, through the transverse sinus. This strategy results in the shortest IMA-to-coronary artery distance and therefore maximizes the use of bilateral IMA grafts [5]. However, surgeons may encounter difficulties getting the in situ RIMA graft to reach distal obtuse marginal branches, particularly in patients with cardiomegaly. We therefore describe a method by which the RIMA is passed behind the superior vena cava (SVC), thereby extending the functional length of the in situ RIMA graft.
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Technique
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The in situ LIMA is harvested in the usual fashion. The sternal retractor is repositioned and the right pleura is widely opened. The RIMA is harvested in a skeletonized fashion. The first intercostal branches are divided to maximize conduit length and to prevent possible postoperative steal syndrome. The lateral pericardium is divided down to the SVC. The SVC is dissected free from the posterior pericardium and the right pulmonary artery, similar to the technique used for bicaval cannulation or pulmonary thrombectomy. Care is taken to avoid damaging the azygous vein, which arises from the posterolateral surface of the SVC. The right phrenic nerve is carefully exposed and inspected on the lateral pericardium. With the aid of magnifying loupes and bipolar cautery, the phrenic nerve and accompanying fat is meticulously dissected free from the surrounding pericardium. The patient undergoes heparinization and the distal RIMA is divided. A groove is made in the paramediastinal fat to accommodate the RIMA. The free end of the RIMA is passed anterior or posterior to the phrenic nerve, then behind the SVC (Fig 1).
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Fig 1. Intraoperative photograph of the skeletonized right internal mammary artery passing anterior to the phrenic nerve (encircled by white vessel loop), then between the superior vena cava and right pulmonary artery, and finally through the transverse sinus. The aorta is encircled by surgical tape (top of picture).
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Cannulation for cardiopulmonary bypass is performed in the usual fashion. A curved clamp is passed behind the heart and through the transverse sinus. The clamp is applied to the free end of the RIMA, which is subsequently pulled through the transverse sinus. This maneuver should be performed during cardiopulmonary bypass, but prior to clamping the aorta. Care must be taken to ensure that the left atrial appendage is not inadvertently clamped or injured during this maneuver. The aortic cross-clamp should be placed as high as possible, staying well away from the RIMA. This technique can also be used for off-pump coronary revascularization.
Myocardial protection is performed in the usual fashion. A bulldog vascular clamp is placed temporarily on the proximal RIMA. The distal RIMA is anastomosed to the obtuse marginal artery using a running 8-0 polypropylene suture. Alternatively, the circumflex artery can be bypassed in the atrioventricular groove. The anastomosis must be completely hemostatic, as bleeding from this location is difficult to address once the cross-clamp is removed. Using this approach, the in situ RIMA can reach nearly any artery in the circumflex territory without tension.
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Comment
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Coronary bypass surgery with bilateral IMA grafts is associated with improved long-term patient survival and decreased cardiac events [1–3]. In situ IMA grafts are considered to be the gold standard for arterial conduits, with patency rates usually exceeding 95% [2–4]. Grafting of the circumflex territory with the RIMA graft is feasible if the conduit is passed through the transverse sinus. However, the length of the RIMA graft occasionally limits the feasibility of this anastomosis.
Taggart and associates [3] recently performed a systematic review of the literature. The authors compared outcomes of bilateral versus single IMA revascularization in more than 15,000 patients. Long-term survival was significantly better in patients who received bilateral IMA grafts, particularly if the grafts were to the LAD and circumflex territories. The strategy of performing LIMA-to-LAD and RIMA-to-circumflex anastomoses may be superior to the RIMA-to-LAD and LIMA-to-circumflex technique, because there is no danger of damaging the RIMA graft during subsequent reoperations. We therefore believe that RIMA grafting of the circumflex territory is an important skill for cardiac surgeons to possess.
Retrocaval positioning of the RIMA enables in situ grafting of distant branches of the circumflex artery. This technique allows the surgeon to gain approximately 2 cm in conduit length. For this procedure we carefully dissected the phrenic nerve away from the surrounding pericardium using bipolar cautery. However, the phrenic nerve can be left attached to a thin pedicle of pericardium, thereby minimizing the risk of damaging this important structure. We have used this technique in 4 patients, without any perioperative complications. Postoperative chest roentgenogram revealed normal function of the right phrenic nerve in all patients. Thallium imaging 6 months after the operation in 3 patients revealed no detectable ischemia in the posterolateral distribution. In the fourth patient both mammary arteries were controlled angiographically, showing perfect anastomosis. With careful surgical technique, retrocaval positioning of the RIMA can be safely used to extend the functional length of the RIMA graft.
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References
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- Lytle B.W., Blackstone E.H., Loop F.D., et al. Two internal thoracic artery grafts are better than one. J Thorac Cardiovasc Surg 1999;117:855-872.[Abstract/Free Full Text]
- 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]
- Taggart D.P., D’Amico R., Altman D.G. Effect of arterial revascularisation on survival: a systematic review of studies comparing bilateral and single internal mammary arteries. Lancet 2001;358:870-875.[Medline]
- Ascione R., Underwood M.J., Lloyd C.T., Jeremy J.Y., Bryan A.J., Angelini G.D. Clinical and angiographic outcome of different surgical strategies of bilateral internal mammary artery grafting. Ann Thorac Surg 2001;72:959-965.[Abstract/Free Full Text]
- Vander Salm T.J., Chowdhary S., Okike O.N., Pezzella A.T., Pasque M.K. Internal mammary artery grafts: the shortest route to the coronary arteries. Ann Thorac Surg 1989;47:421-427.[Abstract]
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Abstract
Introduction
