Histologic and physiologic evaluation of skeletonized internal thoracic artery harvesting with an ultrasonic scalpel

Objectives: The safety and reliability of a method of skeletonized internal thoracic artery harvesting with an ultrasonic scalpel (Harmonic Scalpel; E thicon Endo-Surgery, CVG, Cincinnati, Ohio) were evaluated. Methods: The mural branches of the internal thoracic artery were cut by mea ns of 3 methods, differentiated by distance from the site of application of the Harmonic Scalpel blade to the internal thoracic artery. A total of 15 branches were cut from the internal thoracic artery at (0 mm) the origin (g roup I) or at 1 mm (group II) or 2 mm (group III) distal to the origin. Tis sue preparations were examined for successful vessel closure and severity o f tissue damage. The length of stump (L) and the length of tissue damage fr om the stump (D) were determined by a computer image analysis system, and p ressure testing was performed to evaluate the physical strength of vessel c losure. Results: In group I, 8 of the 15 branches exhibited discontinuity of the va scular wall structure, probably because of insufficient sealing of the divi ded section, and 12 of the 15 branches exhibited tissue denaturation on the internal thoracic artery wall adjacent to areas of origin, which was proba bly caused by the heat transferred from the branches during the process of coagulation. In groups II and III, continuity of wall structure of stumps s uggestive of stable closure of branches was confirmed. The lengths of tissu e damage from the stump (D) were 0.96, 0.58, and 0.63 mm in groups I, II, a nd III, respectively, and the lengths of intact area (L - D) in the corresp onding groups were -0.78, 0.61, and 1.51 mm. The negative figure in group I indicates the presence of tissue damage in the internal thoracic artery it self. By contrast, in groups II and III the internal thoracic arteries were intact, with a safety margin of greater than 0.5 mm, On physiologic evalua tion of vessel closure, 2 of the 24 (8.3%) branches burst under a pressure lower than 350 mm Hg because of insufficient vessel coagulation, but the re maining 22 branches (91.7%) remained intact under pressures up to 350 mm Hg . Conclusion: The internal thoracic artery skeletonization method with an ult rasonic scalpel (Harmonic Scalpel: output level 2) appears to be a safe and reliable method of skeletonized internal thoracic artery harvesting when b ranches are sectioned at least 1 mm distal to their origin at a sufficientl y slow speed.