Viability of the rectus abdominis muscle following internal mammary artery ligation

The purpose of this study was to determine if the rectus abdominis muscle in the dog model could be used as a transposition flap based on its proximal blood supply following ligation of the internal mammary artery. In 11 dogs, the left internal mammary artery and vein were ligated at the fifth intercostal space. Both the left and right rectus abdominis muscles were elevated from their respective beds, dividing the inferior epigastric and intercostal vascular pedicles. Each muscle was then wrapped in a thin silicone sheet and replaced. One week later the dogs were returned to surgery and the muscles inspected. The right rectus abdominis muscle was completely viable in all the dogs. In 10 of the 11 dogs, the left rectus abdominis muscle was completely viable. We conclude that a superiorly based rectus abdominis muscle in the dog can maintain its viability following ligation of its proximal blood supply at the fifth intercostal space.