Asian Cardiovasc Thorac Ann 2007;15:339-341
© 2007 Asia Publishing EXchange Ltd
Internal Thoracic Artery Side Branch Ligation for Post Coronary Surgery Ischemia
Kosmas Tsakiridis, MD,
Dimitrios Mikroulis, MD,
Vassilios Didilis, MD,
Georgios Bougioukas, MD
Department of Cardio-Thoracic Surgery, University of Thrace, Alexandroupolis, Greece
For reprint information contact: Dimitrios Mikroulis, MD, Tel: 30 25 5107 4166, Fax: 30 25 5107 4164, Email: dmikrou{at}med.duth.gr, Department of Cardio-Thoracic Surgery, General University Hospital of Alexandroupolis, Alexandroupolis P.C. 68100, Greece.
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ABSTRACT
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Two cases of internal thoracic artery side-branch ligation in patients with recurrent angina after coronary bypass are reported with long-term follow-up. Ligation was performed with clips via a left thoracotomy. Treadmill stress testing after 3 and 4 years did not provoke any myocardial ischemia. These findings suggest that an unligated side-branch can produce a steal phenomenon.
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INTRODUCTION
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Angina after coronary artery bypass grafting (CABG) may be due to many causes including patent internal thoracic artery (ITA) side branches.1 The major branch of the ITA is the lateral costal artery, also known as the large 1st intercostal artery, lateral mammary, lateral costal branch, retrocostal artery, lateral infracostal artery, or large pectoral branch.2 It descends on the inner surface of the chest wall (Figure 1
). The hemodynamic significance of a patent ITA side branch is still controversial. Some reports support the concept of flow steal, with ligation of the ITA side branch as the appropriate treatment; others maintain that ITA steal is very unlikely because the left coronary system is perfused in diastole while the chest wall artery system is perfused in systole. We report 2 cases of successful left ITA (LITA) side-branch ligation with long-term follow-up in patients who had recurrent angina after CABG.
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Figure 1. The lateral costal artery (LCA) from the internal thoracic artery (ITA) as seen during video-assisted thoracic surgery.
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CASE REPORT
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Case 1
A 64-year-old man underwent quadruple CABG through a median sternotomy in another country. The grafts included LITA to the left anterior descending artery (LAD), and saphenous vein to the circumflex artery, right coronary, and 1st posterolateral branch. He presented 9-years later with angina pectoris (Canadian Cardiovascular Society class 3) despite maximal antianginal therapy. Myocardial ischemia in the anterior wall was documented on a thallium perfusion scan during exercise. Diagnostic cardiac catheterization revealed all vein grafts were occluded except the one to the 1st posterolateral branch. The LITA bifurcated into equal segments (Figure 2). The LITA-to-LAD anastomosis was patent but with low flow. The LITA side branch was recognized as the lateral costal artery. Via a left lateral small extrapleural thoracotomy into the 2nd intercostal space, the lateral costal artery was visualized and ligated with clips.
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Figure 2. Cine angiography in case no. 1; the left internal thoracic artery (ITA) bifurcates into 2 equal branches. LCA = lateral costal artery.
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Clinical improvement was detected, with immediate relief of angina. The postoperative course was uneventful, and the patient was discharged after 4 days. At the 4-month follow-up, he reported no angina, and treadmill stress testing did not provoke any myocardial ischemia. Treadmill stress testing has been repeated annually, and thallium scintigraphy at 4 years postoperatively did not indicate any myocardial ischemia.
Case 2
A 63-year-old man underwent triple CABG (LITA to LAD, saphenous vein to the circumflex artery and right coronary artery sequential to the posterior descending coronary artery) in our center. He presented 6-months later with recurrent angina. On coronary angiography, the sequential graft was occluded and the other vein graft was not found. The LITA-to-LAD graft was patent, and the artery bifurcated into 2 equal segments. There was no further progression of native coronary artery disease, but a laterally directed LITA side branch was noted, suggesting the possibility of preferential flow through the side branch (Figure 3). The LITA-to-LAD anastomosis was technically sound. This patient also underwent a left lateral small extrapleural thoracotomy to ligate the lateral costal artery. He experienced immediate relief of angina, with no recurrence on follow-up, and negative treadmill stress tests. Thallium scintigraphy in the 3rd year after the operation indicated no myocardial ischemia.
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Figure 3. Cine angiography in case no. 2; panoramic view of the lateral costal artery (LCA) branch and the left internal thoracic artery (ITA) anastomosis to the left anterior descending artery (LAD).
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DISCUSSION
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Internal thoracic artery steal syndrome is still controversial. Morocutti and colleagues3 showed by intracoronary Doppler that trial occlusion of LITA side branches with a balloon technique increased flow through the LITA. Pagni and colleagues4 described a patient with a large ITA side branch that produced recurrent angina 3 years after minimally invasive CABG. Transcatheter coil obliteration of the vessel gave symptomatic relief, but chest pain recurred 6-months later due to unwinding of the coil and recanalization of the collateral vessel. The culprit branch was successfully ligated by a video-assisted approach. They claimed that ITA steal can occur, and recommended a video-assisted approach to control anomalous ITA branches in the occasional patient with a failed endovascular procedure. Using transthoracic echo-Doppler, Gaudino and colleagues5 evaluated ITA flow at rest and during peripheral vasodilatation. They concluded that the hemodynamic importance of ITA side branches is small in most patients, both at rest and during peripheral vasodilatation. Kern6 demonstrated minimal flow diversion into the side branch at rest or during adenosine-induced coronary hyperemia. However, these findings contrast with clinical and 24-hour electrocardiogram monitoring evidence of ischemia relief after LITA side-branch embolization.7 Hartz and Heuser8 documented with a thallium perfusion study the relief of symptoms and ischemic changes after embolization of an ITA side branch. To our knowledge, these are the first 2 cases showing angina relief on long-term follow-up. The anastomoses were made without technical flaws, and the diameters of the ITA and distal LAD were appropriate. Thallium scintigraphy in both patients gave evidence of good ITA flow.
The incidence and clinical importance of the lateral costal artery should not be underestimated. Barberini and colleagues2 stated that it courses to some extent along the "milk line" and anastomoses with the intercostal arteries, sharing their zones of blood supply. Therefore, it was suggested that the lateral costal artery may act as a supernumerary mammary artery, potentially able to furnish accessory breasts. Many methods have been recommended to interrupt the blood supply to ITA side branches. These include transcatheter occlusion from a femoral or brachial approach; however, we do not suggest this technique due to increased evidence of recanalization and the risk of injury to the ITA.3,4 The most common technique is a video-assisted procedure, and when possible, this should be the treatment of choice.4 When not possible (e.g., extended adhesions), a left lateral small extrapleural thoracotomy is an effective alternative, as demonstrated in our 2 cases.
The persistence of undivided LITA branches is not the exception but the rule, as the literature demonstrates. Major factors contributing to ITA side-branch steal include: technical errors (anastomotic stenosis, unligated large ITA side branches during harvesting) or anatomic factors (small quality and diameter of the distal ITA or the target vessel), which reduce ITA run-off and possibly divert it into large side branches with lower resistance. Our cases support the existence of the steal phenomenon, and a left lateral small extrapleural thoracotomy is feasible for lateral costal artery ligation. The most important factor is to ensure that high take-off branches from the ITA are clipped at the initial operation.
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REFERENCES
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- Horowitz MD, Oh CJ, Jacobs JP, Chahine RA, Livingstone AS. Coronary-subclavian steal: a cause of recurrent myocardial ischemia. Ann Vasc Surg 1993;7:452–6.[Medline]
- Barberini F, Cavallini A, Carpino G, Correr S, Brunone F. Lateral costal artery: accessory thoracic vessel of clinical interest. Clin Anat 2004;17:218–6.[Medline]
- Morocutti G, Gasparini D, Spedicato L, Gelsomino S, Paparella G, Bernardi G, et al. Functional evaluation of steal by unligated first intercostal branch before transcatheter embolization in recurrent angina after a LIMA-LAD graft. Cathet Cardiovasc Interv 2002;56:373–6.[Medline]
- Pagni S, Bousamra M 2nd, Shirley MW, Spence PA. Successful VATS ligation of a large anomalous branch producing IMA steal syndrome after MIDCAB. Ann Thorac Surg 2001;71:1681–2.[Abstract/Free Full Text]
- Gaudino M, Serricchio M, Tondi P, Glieca F, Bruno P, Possati G, et al. Do internal mammary artery side-branches have the potential for haemodynamically significant flow steal? Eur J Cardiothorac Surg 1999;15:251–4.[Abstract/Free Full Text]
- Kern MJ. Mammary side branch steal: is this a real or even clinically important phenomenon? Ann Thorac Surg 1998;66:1873–5.[Free Full Text]
- Soliotis F, Al-Kutoubi A, Handler CE. Transbranchial coil occlusion of the first intercostal branch of an internal mammary artery bypass graft for angina. Int J Cardiol 1997;59:206–8.[Medline]
- Hartz RS, Heuser RR. Embolization of IMA side branch for post-CABG ischemia. Ann Thorac Surg 1997;63:1765–6.[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
