Methods: Under general anaesthesia left thoracotomy was carried out on eight Mongrel dogs. The left anterior descending coronary artery was stabilized using Octopus2 and occluded with a bulldog clamp. Coronary arteriotomy was carried out and filtrated high flow room air was insufflated for ten minutes. Tissue samples were taken from the procedure area as Group I (n = 8), and from the proximal part of the occlusion as control Group II (n = 8). Tissue samples were processed for scanning electron microscopic examination. Examination and scoring of endothelial injury were performed in blind fashion, and results were analyzed statistically.

Results: There was no endothelial damage in one sample while Type I injury in six samples and Type II injury in one other were observed in Group I. In Group II, Type I injury was observed in only one sample, whereas no damage was observed in the other seven samples. There was statistically significant difference between the groups in the meaning of frequency of endothelial injury.

Conclusion: This study reveals that intermittent insufflation of the filtrated high flow room air to the coronary anastomotic area for ten minutes may frequently cause Type I and rare Type II endothelial injury. Because of the risk of endothelial injury, air blower should be used cautiously and be modified so as to decrease the risk of endothelial injury.