Asian Cardiovasc Thorac Ann 2006;14:e33-e34
© 2006 Asia Publishing EXchange Ltd
Coronary Artery Bypass Grafting Using a Bifurcated Internal Thoracic Artery
Satoshi Numata, MD,
Yuichiro Murayama, MD,
Osamu Sakai, MD,
Keitaro Koushi, MD
Department of Cardiovascular Surgery, Kyoto First Red Cross Hospital, Kyoto, Japan
For reprint information contact: Satoshi Numata, MD Tel: 81 75 561 1121 Fax: 81 75 561 6308 Email: snumat{at}yahoo.co.jp, Department of Cardiovascular Surgery, Kyoto First Red Cross Hospital, 15-749 Honmachi, Higashiyama, Kyoto 605-0981, Japan.
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ABSTRACT
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Coronary artery bypass grafting was performed successfully on a patient by anastomosing the left internal thoracic artery and its pericardiacophrenic branch to the obtuse marginal and the posterior descending coronary artery, respectively, to form a Y graft. Preoperative angiography of the internal thoracic artery had revealed the presence of an unusually large pericardiacophrenic branch almost the size of the main trunk, which allowed us to plan for bifurcated artery grafting.
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INTRODUCTION
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The internal thoracic artery (ITA) is the preferred graft for coronary artery bypass grafting (CABG) because it provides sufficient flow and superior long-term patency. We report the case of a patient with an unusually large side branch of the left ITA (LITA) that allowed us to fashion a Y-shaped graft.
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CASE REPORT
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A 58-year-old male who had been treated previously for hypertension and diabetes was examined following complaints of dyspnea. Coronary angiography revealed 75% stenosis of the left main trunk and 90% stenosis of the posterior descending artery. Left ventriculography showed hypokinesis of the anterior and posterior walls. The left ventricle had an end-diastolic volume index of 84.8 mL·m–2, an end-systolic volume index of 39.0 mL·m–2, and an ejection fraction of 55%. Angiography showed that the LITA originated from the subclavian artery and descended vertically before dividing into the superior epigastric and musculophrenic arteries at the level of the 6th rib. At the level of the 4th rib, it gave off a huge branch that ran tortuously to the left side (Figure 1
). This branch was about the size of the ITA at the level of the 6th intercostal space. The patient’s ankle-brachial index was normal.
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Figure 1. Preoperative angiogram showing a major side branch arising from the left internal thoracic artery.
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Bypass surgery was performed through a median sternotomy without using cardiopulmonary bypass. The LITA was harvested using an ultrasonic scalpel. It had a major side branch that ran along the surface of the pericardium (Figure 2) and was long enough to reach the posterior descending artery. The LITA was anastomosed to the obtuse marginal artery and the large side branch to the posterior descending artery. The right ITA was also harvested and anastomosed to the left anterior descending artery. The patient was extubated the next day. The postoperative course was uneventful, and angiography demonstrated good patency of the bifurcated graft. The patient was discharged without any complications.
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Figure 2. Operative view of the major pericardiacophrenic branch (white arrow heads) of the left internal thoracic artery.
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DISCUSSION
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The ITA usually originates from the subclavian artery and divides into the superior epigastric and musculophrenic arteries. Several side branches diverge from the length of the ITA, including usually the lateral costal, pericardiacophrenic, and sternal branches. All the side branches must be ligated when the ITA is harvested to avoid recurrence of angina as a result of an unligated lateral costal branch.1
As some anatomical variability exists, we believe that preoperative angiography of the ITA to accurately assess the anatomical structure of the vessel is desirable so as to ensure safe harvesting. A study found the lateral costal branch present in 15% of 100 cadavers examined, located 1.3 to 3.8 cm (mean distance, 2.5 cm) from the origin of the ITA.2 The pericardiacophrenic branch arose at a distance 2.5 to 7.6 cm (mean, 4.3 cm) from the origin of the ITA. Preoperative angiography will disclose these variations. In the present case, preoperative angiography revealed the presence of a large side branch, thereby allowing us to decide on bifurcated ITA grafting in advance. Although this branch was sufficiently large in our patient to be readily visible during ITA harvesting, we could not have confirmed its length and shape without preoperative angiography. Routine preoperative angiography for the purpose of detecting this kind of anomaly may not be feasible, but it may have a place in bypass surgery.
Coronary artery bypass grafting with bifurcated ITA grafts has been described, using the superior epigastric and musculophrenic arteries to construct a Y graft to the coronary arteries, specifically to the left anterior descending artery and the diagonal branch.3 The superior epigastric and musculophrenic arteries are often small and do not contain elastic lamellae.4 We cannot compare our case with these published cases because our patient had a large branch that was almost the same size as the ITA itself. We anticipate good patency in our case as would be achieved with a normal in situ ITA graft.
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REFERENCES
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- Schmid C, Heublein B, Reichelt S, Borst HG. Steal phenomenon caused by a parallel branch of the internal mammary artery. Ann Thorac Surg 1990;50:463–4.[Abstract/Free Full Text]
- Henriquez-Pino JA, Gomes WJ, Prates JC, Buffolo E. Surgical anatomy of the internal thoracic artery. Ann Thorac Surg 1997;64:1041–5.[Abstract/Free Full Text]
- Olearchyk AS, Sherafat M. Bifurcated ("Y") internal thoracic-coronary artery grafts. J Thorac Cardiovasc Surg 1992;103:601.[Medline]
- van Son JA, Smedts F. Bifurcated ("Y") internal thoracic-coronary artery grafts. J Thorac Cardiovasc Surg 1993;106:945–6.[Medline]
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