Coronary Artery Bypass Grafting

Abstract

1. The median sternotomy is completed and if the internal thoracic artery (ITA) is to be used, the next step is to elevate the left sternal leaf. The ITA and its two venous comitantes can be identified visually and palpated in most patients. The position of the artery is extremely constant (5–10 mm lateral to the sternal edge) so that if it cannot be identified by inspection or palpation (as occasionally happens when fat or muscle obscurses it), the dissection can be initiated at the sternal edge and carried through the pleura, endothoracic fascia, and sternalcostalis muscle to expose the underlying fatty tissue and the medial internal mammary vein. The ITA is divided distally at the sixth intercostal space where it divides into the superior epigastric artery and the musculophrenic artery. I divide the artery at this time, although some surgeons believe the artery should not be divided until heparin is given. Dissection is then carried proximally, creating a pedicle of tissue approximately 1.5 to 2 cm in width and continued to the anterior surface of the subclavian vein. Bleeding from branches is controlled by clips, electrocautery, or both. Some surgeons prefer not to enter the pleural space; I believe the pleural space should be entered widely to identify the definitive position of the ITA. If the pleura is left intact and the lungs are hyperexpanded, a much longer ITA length is needed so that it may not reach a distal site and the distal diameter of the ITA will be smaller in many instances (i.e., the more distal the ITA is used, the smaller it is). Additionally, should the patient require a later operation, there is much greater potential for inadvertent injury to the ITA.