Background: We presented the histologic findings of clipped and perfused internal thoracic arteries (ITA) examined using a transmission electron microscope (TEM) in patients undergoing coronary artery bypass grafting (CABG) surgery.

Methods: Sixty patients were randomly selected for this study and divided into two different groups according to the ITA harvesting method. In the first group [clipped group (CG); n=38], the ITA was prepared with a pedicle; the distal part was clipped, cut, and covered with a papaverine-soaked cloth until the anastomosis time. In the second group [perfused group (PG); n=22], the graft was not cut after ITA harvesting and was left in the thorax with perfusion until the time of anastomosis. Just before the ITA anastomosis, an ITA ring of 1 mm length was cut and preserved in 2.5% glutaraldehyde solution. The histological descriptions of the samples were done according to the following subgroups: (i) completely confluent endothelium; (ii) partially confluent endothelium; (iii) loosely netted endothelium; (iv) islands of endothelium; and (v) no endothelium.

Results: In the CG group, different degrees of histopathologic findings were recorded in eight patients (21.05%). In the PG group, endothelial or subadventitial pathology was seen in two patients (9.09%) in the histopathological examinations of ITA. The most important histopathological findings of ITA were as follows: endothelial vacuolization, intimal thickening and/or intimal separation, subendothelial edema, edema in cytoplasma and mitochondria.

Conclusion: Clipping of the ITA after harvesting may damage the integrity of the cell skeleton. Our study showed that the sudden occlusion of the ITA conduits harvested using the standard technique induces a non-physiological condition and may cause an impairment in the endothelial continuity during this pathological process in the endothelium and cellular blood elements.

Keywords : Clipping; endothelial damage; histology; internal thoracic artery; tranmission electron microscope