Clinical significance of internal thoracic artery morphometry and inter-ethnic differences

The internal thoracic artery (ITA) is used extensively for coronary revascularisation. Clinical observations suggest an inter-ethnic difference in ITA morphometry between Indians and whites presenting for coronary artery bypass surgery. However, accurate morphometric data comparing these ethnic groups were not available. This study analyses the morphometry of the left and right ITAs in 60 cadavers (43 blacks, 9 whites, 8 Indians). The lengths of the arteries were measured and the external diameters were recorded at the origin of the 1st, 4th and 6th costal cartilages. Significant differences in length and diameter on the right and left sides between ethnic groups were demonstrated. In particular, these differences were marked between the white and Indian groups. Clinically, these differences can be so marked that in some instances the left ITA in Indian patients is so small at the distal point of take-down as to be unsuitable for use as an arterial conduit. This is one of the reasons that has prompted the use of the ITA as a composite graft. Our study appears to be the first to highlight this inter-ethnic difference and to support the clinical impression.