[Angiographic characteristics of the internal thoracic artery--anatomic variations and their surgical importance]

Abstract

Introduction: The internal thoracic artery is considered the graft of choice for surgical revascularization of the ischemic myocardium. The real incidence of anatomic variations of the internal thoracic artery is not known, although it is an extremely important issue, considering surgical strategy, as well as immediate and long-term outcome.

Material and methods: During a period of three months (Jun. 1st-Aug. 31st 1998) we have evaluated the left internal thoracic artery (ITA) in 80 randomly selected patients (62 men, average age being 57.4 +/- 5.2).

Results: Typical take-off, side branches, terminal division and absence of any atherosclerotic lesions were noted in 69 patients (86.25%). Angiographically apparent atherosclerotic lesions were not noted; anomalous take-off from the left subclavian artery was noted in 9 cases (11.25%--including one case of aneurysmatic proximal portion of the ITA); there were two cases where the lateral thoracic artery was present (2.5%) and three cases where the distal division was of a trifurcation type, which is not of surgical importance (3.75%). Average diameter of the left ITA was 2.19 +/- 0.24 mm for the entire group (2.20 +/- 0.19 mm for men, and 2.10 +/- 0.21 mm for women, p = NS).

Discussion: Results that we have obtained are in accordance with previously published data. We did not find significant (angiographically visible) atherosclerotic lesions of the ITA, however variations in the take-off and branching were found to be frequent (11.25%). Aneurysmatic left ITA is an extremely rare finding in the literature. Angiographically found variations (capable of causing coronary steal) are impossible to be detected during operation. This raises a question of a need for routine angiographic evaluation of the ITA before operation. For some patients, routine angiographic evaluation of the ITA before myocardial revascularization is mandatory: in pts with previous myocardial revascularization, in whom ITA was not used, but could have been damaged; in pts with atherosclerotic lesions of the supraaortic vessels; in pts with previous irradiation of the anterior mediastinum (ITA could be fibrotic); in pts with actual or corrected coarctation of aorta (ITA could be aneurysmatic).

Conclusion: The incidence of anatomic variations of the ITA (that may be of surgical importance) is not negligible (13.25%). These data indicate that routine angiographic evaluation of the ITA should be considered in all patients in need for myocardial revascularization.