ANATOMIC STUDY OF THE COLLATERAL BLOOD-SUPPLY OF THE STERNUM

A microdissection study was carried out on ten injected, cleared human sternal specimens. Three types of vessel were identified that have th e potential to carry blood to the sternum after mobilization of the in ternal thoracic artery (ITA): (1) branches of the ITA that supply both the sternum and the pectoralis major (''sternal/perforating branches' '), (2) branches of the ITA that supply both the sternum and an adjoin ing intercostal space (''sternal/intercostal branches''), and (3) post erior intercostal arteries that do not anastomose with an ITA branch b ut continue past the ITA to reach the sternum. All three types of vess el were found more frequently in the proximal than in the distal half of the sternum. For sternal/perforating and sternal/intercostal vessel s to function as collaterals after ITA bypass grafting, their short co mmon trunks of origin must remain intact. The data support the recomme ndation that the branches of the ITA be ligated as close as possible t o the ITA itself to preserve collateral blood now to the sternum.