Step-by-Step Tutorial of Internal Mammary Artery Harvesting

Internal mammary artery harvesting is a skill all cardiothoracic surgery residents must perfect early in their careers. Improper technique can lead to inferior short- and long-term outcomes. Not only are the number of available resources to learn proper technique limited, but intraoperative visualization is quite difficult from an assistant’s point of view. A well-produced video is of utmost importance for adequate visualization and teaching purposes.  

There are different ways to harvest a mammary artery, including skeletonized and pedicled. This video provides the step-by-step approach for a pedicled takedown.  

Steps in Internal Mammary Artery Harvesting 

1. A median sternotomy with dissection of the retrosternal tissue should be performed. A Chevalier or Rultract retractor can be used to elevate the hemi-sternum. First, place the two rakes with one positioned at the manubriosternal junction and the other one by the xiphoid. Then insert the right-sided retracting edge with the transverse bar oriented inferiorly. Crank open gently to allow adequate visualization of the left internal mammary artery (LIMA). 
2. Start standing up with the table low and the electrocautery on 45. Dissect the fatty tissues off the endothoracic fascia with the #1s in the left hand and the electrocautery in the right hand. Ensure that you are in an avascular plane, and carry this dissection laterally enough to visualize the internal mammary artery. 
3. Dissect tissue off the back of the sternum, starting inferior and moving superiorly, ideally exposing the subclavian vein at this stage to define the entire extent. Perform enough dissection to expose the medial and lateral aspect of the LIMA bundle. The pleural space can be opened to help with visualization of the LIMA. 
4. Then, using electrocautery, mark the medial and lateral aspects of the LIMA by carrying the mark a few millimeters medial and lateral to the veins that run parallel to the LIMA. The safest approach is to start at the edge of the sternum when initially locating the LIMA. Use forceps to pull down the fascia and the electrocautery to start opening the fascial plane. 
5. Once you have opened the fascia superiorly in the region of the manubrium, raise the table for optimal visualization of the LIMA. 
6. Now extend the incision inferiorly all the way to the xyphoid in the medial fascia along rest of length of vessel inferiorly. Once you reach the xyphoid, you will have to divide muscle. Be careful in the superior-most and inferior-most aspects for aberrant anatomy. 
7. After opening fascia along the length of the vessel, take the IMA off the chest wall. Start at the distal third of LIMA, first working distally and then working back proximally. 
8. Find a plane just under the rib to determine which branches must be isolated. Use clips to isolate these branches right on the IMA and accompanying veins. Be sure to cauterize the branches adjacent the chest wall, away from the clip. This will allow you to place another clip should it be required. 
9. Once approximately two-thirds of the length of the IMA is freed medially along with any branches, incise the endothoracic fascia laterally. Be sure to stay on the lateral vein. 
10. When a significant segment of IMA is off chest wall, use the electrocautery to peel the fascia away from vessels to create a semi-skeletonized LIMA. 
11. Next, identify the proximal venous bifurcation and divide the medial vein proximally by placing two medium clips superiorly and one inferiorly before dividing. 
12. Once you have reached the distal bifurcation and are satisfied with the proximal extent of the IMA (you have visualized the subclavian vein and have divided all intercostal branches), you are ready to give full heparin for bypass. 
13. Divide the distal branches of the IMA, which is generally achieved by placing clips on each of the two distal branches—the musculophrenic and superior epigastric arteries. This is the inferior extent of the LIMA harvest. 
14. Cut the IMA with sharp scissors, and then assess flow and pulsatility. 
15. Place two additional clips on the distal cut edge of the IMA branches. 
16. Lay a sponge underneath the IMA, spray it with papaverine, roll the LIMA longitudinally from distal to proximal, and then tuck it into the left pleural apex. 
17. Finally, remove the Chevalier retractor and proceed with the remainder of the operation

Reference

1. Viral Patel, Omar Hussian, Faisal Bakaeen, Chapter 4 - Harvesting the skeletonized internal mammary artery, Mario Gaudino, Technical Aspects of Modern Coronary Artery Bypass Surgery, Academic Press, 2021, Pages 27-39, ISBN 9780128203484, https://doi.org/10.1016/B978-0-12-820348-4.00004-2.

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