Thoracoscopic approach of the internal mammary artery (IMA): a training model in pigs

Endoscopic internal mammary artery (IMA) approach represents a well-established procedure in coronary bypass surgery. However, such techniques require highly trained skills that need to be mastered in experimental models before taken into the clinic. To attain such skills, our aim was to develop a training model of thoracoscopic approach for harvesting of the IMA in pig. Ten pigs of either sex, weighing 20-28 kg, were used. The thoracic cavity was accessed with the animal in a lateral decubit position, through two ports of 10 mm and 1 of 5 mm, inserted on the anterior and posterior axillary lines immediately below the infrascapular angle into the pleural cavity, and a 30 degrees Hopkins II telescope. The internal mammary artery (IMA) was identified and dissected from its origin in the subclavian artery until its distal part where it becomes the deep superior epigastric artery. Afterward, the arterial segment was clipped and harvested. The mean operative time was 73 min. Postoperative survival at 72 hours was 100% and 90% at 4 weeks. A mean length of 3.2 cm of IMA graft was obtained (2.8-4 cm). The pig IMA has no intercostal branches; thus, the mobilization of the vessel being greatly facilitated. The procedure has two critical steps: the proper trocar insertion and the dissection of the middle one-third of the IMA. Endoscopic-assisted IMA, harvesting in pigs, represents a useful tool for training in minimally invasive heart surgery and supports further development toward other clinical applications.