[Mechanical dilation of the internal thoracic artery graft by using balloon catheter]

We evaluated the free flow of the internal thoracic artery grafts (ITA) which were dilated with a balloon catheter. Further, we examined the postoperative angiographic findings and histology of the ITAs by scanning electron microscopy. In 25 patients with internal thoracic artery grafting, the artery was dilated with a balloon catheter (Fogarty IMAG kit) that was withdrawn at tensions of less than 30 gm. The mean free flow rate of the left ITAs (LITAs) increased from 64.2 ml/min to 101.9 ml/min by injection of papaverine to ITAs (p < 0.05). The mean free flow rate of the balloon dilated LITAs were 160.8 ml/min which was significantly higher when compared with that of control and papaverine (p < 0.01, p < 0.01). The mean free flow rate of the balloon dilated right ITAs (RITAs) showed 183.2 ml/min, it was significantly higher (p < 0.01, p < 0.05) compared with that of control (78.4 ml/min) and papaverine (129.2 ml/min). Irregularity was documented in 16% of the ITAs in spite of the great patency rate (100%) from the postoperative angiogram. Using scanning electron microscopy, endothelial cell borders were well demarcated in the proximal portion of the dilated ITA. However, the distal portion of the endothelium displayed gradual destruction. Although mechanical dilation of the ITA graft by balloon calibration is very effective in increasing the free flow rate of ITA, we should be prepared for the intimal damage of the ITA graft.