J Thorac Cardiovasc Surg 2004;128:490-491
© 2004 The American Association for Thoracic Surgery
Studying the lumen in composite Y internal thoracic artery–saphenous vein grafts
José Glauco Lobo Filho, MD, MM, PhD,
Maria Claudia de Azevedo Leitão, MD,
Antonio Jorge de Vasconcelos Forte
ICORP, Clinical Research, Fortaleza, Brazil
To the Editor:
We congratulate Gaudino and colleagues1for the splendid idea advanced in their study on composite Y internal thoracic artery (ITA)–saphenous vein (SV) grafts. The study of the lumen contributes enormously to the current series of studies describing the characteristics of composite grafts. However, we do not share some of the opinions presented in this article. We believe that it is not right to use the term "flow steal" in this specific case, because the circulatory system is pressurized, is closed, and responds well to demand. We do not agree that SV grafts are the worst conduits. It is already known that SVs in aorta–left anterior descending coronary artery grafts are patent in 70% to 80% of the patients after 10 years. We also believe that the reduced diameter in distal ITA used to revascularize coronary arteries that have a proximal moderate stenosis (<70%) is physiologic and expected. The distal ITA lumen may be reduced as well when the supplied coronary artery has a poor runoff. If there is no flow demand, the ITA graft will decrease in caliber, because ITA has a huge ability to adapt itself to flow demand. It is commonly seen that an ITA supplying coronaries with proximal severe stenosis and a good runoff is usually dilated.2 The fact that SV is less reactive does not compromise the coronary irrigation to which it is anastomosed, because the blood flow in SV is proportional to the coronary runoff and not to its diameter. Nevertheless, we agree with current studies that demonstrate ITA's capacity to adapt to flow demand.3 We strongly believe that SV segments do not jeopardize the composite graft efficiency and have several advantages when used in such configuration: they are smaller, they suffer less pressure and shear stress, and they receive substances produced by ITA's endothelium (nitrous oxide, for example). These advantages are believed to increase SV graft durability.4-6 One must also question results from an experiment that did not use a group control; in addition, the small sample does not allow for definite conclusions, indicating the need for more research in this area.
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References
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- Gaudino M, Alessandrini F, Pragliola C, Luciani N, Trani C, Burzotta F, et al. Composite Y internal thoracic artery–saphenous vein grafts. short-term angiographic results and vasoreactive profile. J Thorac Cardiovasc Surg. 2004;127:1139-1144.[Abstract/Free Full Text]
- Ochi M, Hatori N, Bessho R, Fujii M, Saji Y, Tanaka S, et al. Adequacy of flow capacity of bilateral internal thoracic artery T graft. Ann Thorac Surg. 2001;72:2008-2012.[Abstract/Free Full Text]
- Lobo Filho JG, Leitão MC, Lobo Filho HG, Silva AA, Machado JJ, Forte AJ, et al. Myocardial revascularization surgery using composite Y-graft of the left internal thoracic artery. blood flow analysis. Rev Bras Cir Cardiovasc. 2004;19:1-8.
- Cox JL, Chiasson DA, Gotlieb AI. Stranger in a strange land. the pathogenesis of saphenous vein graft stenosis with emphasis on structural and functional differences between veins and arteries. Prog Cardiovasc Dis. 1991;34:45-68.[Medline]
- Nwasokwa ON. Coronary artery bypass graft disease. Ann Intern Med. 1995;123:528-545.[Abstract/Free Full Text]
- Tarr F, Dudas G, Tarr M, Racz R, Sasvari M, Tomcsanyi I. Analysis of the stable metabolite of endothelium-derived nitric oxide of internal mammary artery bypass grafts at the venous drainage system of the recipient coronary artery. morphologic implications and consequences. Orv Hetil. 2002;143:2549-2552.[Medline]
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References