Internal Mammary Perforator Preserving Nipple-Sparing Mastectomy (IMP-NSM) to Reduce Ischemic Complications

CHAPTER 1

Hi, I'm Dr. Mardi Karin. I specialize in breast cancer surgery at Stanford University in California. I've been studying over a hundred breast MRIs to evaluate the blood supply to the nipple areolar complex to determine what can be preserved during nipple-sparing mastectomy. I'm going to demonstrate a technique of preserving the dominant blood flow to the nipple areolar complex in the majority of patients during nipple-sparing mastectomy, which comes from a perforator through the pectoralis major muscle from the internal mammary vessels at the sternal border. I call this internal mammary perforator preserving nipple-sparing mastectomy or IMP-NSM. I'm gonna be showing you all the techniques. We start with reviewing the breast MRI if it has been done and evaluating the blood flow, which is a guide at surgery and can help with preservation. However, the same technique works even if the patient does not have a breast MRI. I'll be demonstrating that now.

CHAPTER 2

The first step is to review the breast MRI if they have it. The radiologist created what's called a MIP image, which is a maximal intensity projection, which averages multiple slices. It makes the skin look thicker but it also shows the blood supply very well. It shows that to the right nipple, the dominant blood flow comes from this perforator from the internal mammary vessels, which you can see here. And the perforator comes up through the pectoralis major and courses up here to get the closest to the nipple. So I call that dominant. In her, there's actually a second one. So this probably runs in the subcutaneous tissue. It actually even supplies this lateral breast, which is a little more unusual. Typically this will come up and also supply the nipple area. So she definitely has a dominant internal mammary perforator blood supply to the nipple areolar complex because this is the main blood vessel and extends the closest to the nipple area. On the left side, we see one coming out and then branching. And this again clearly, from the internal mammary perforators, extends the closest to the nipple areolar complex. So we call that internal mammary perforator or IMP-dominant blood supply to the nipple. This is her cancer here in the right breast. And then down here we get little thumbnails that say MIP or M-I-P image and the reformats that are created by the radiologist - and they can be rotated. The image is just not quite as bright, but that can be adjusted for. But you clearly see the internal mammary vessels and you can also see the main blood supply to the nipple, which is here coming from that internal mammary perforator. That's her cancer over there. So our radiologist typically will have a MIP reconstruction, but if not, it can be easily created by the radiologist because it's a reformat.

CHAPTER 3

Okay, this is the patient. She's been marked by the plastic surgeon for either an IMF scar or a radial scar, whichever is needed. In her case because her cancer on the right is located near the inframammary fold, we're gonna do an IMF scar. So the first step is to mark the intercostal spaces. This is the sternal notch. So I mark that and then the next one is going to be the third intercostal space. Which I'm gonna mark right at the sternal border and extending laterally. I usually mark the fourth intercostal space, which often is the blood vessel to the breast tissue, but sometimes there's a branch coming anteriorly there. And then a dotted line about a centimeter laterally. And this ends up being the zone where we find the internal mammary perforator. Typically at this third, or sometimes at the second intercostal space. It's typically right superior to the line that is marked for the superior edge of the breast tissue. Marking the intercostal spaces where we see the internal mammary perforator. We already marked the other side, and that's the second, the third, and the fourth intercostal space. I try to put this mark right at the sternal border as a guide and then a dotted line about one centimeter lateral to the sternal border. Internal mammary perforator, or IMP, will usually perforate the pectoralis muscle right along this line, usually just superior to where the superior edge of the breast tissue is marked. That's why it can be preserved, because it usually perforates here or here.

CHAPTER 4

I got your Telfa right here, Dr. Mardi. Thank you. Her breast MRI shows that the cancer is close to the skin right at the inframammary fold. Do you have the tumescence ready? Yes ma'am. Awesome. Okay, so now I'm gonna just not pull on that, and we'll do the upper part a little bit more, and I'll tack that back up as the inferior margin on the cancer.

CHAPTER 5

Now injecting tumescence, and we go to the edges of the breast tissue. I'm showing you where the needle is. It's about in the subcutaneous tissue over the glandular breast tissue. And it's important to go just to the edge of the line. You do not want to go past over the sternal border because that creates too much hydrodissection over the sternum. Now I'm up to the top. Actually, there's the tip of the infusion cannula. And it's right in the sub-q. It's a blunt tip. This is a very dilute solution of epinephrine. or 1% lidocaine with epinephrine. And I do not inject behind the nipple areolar complex.

CHAPTER 6

You start to see the tumescence there, which is clear fluid. There was no tumescence here. It helps the pectoralis fascia separate posterior. It diffuses all the way down to the pec fascia, which I'm taking up now. With an IMF scar, do this part of the operation early.

In an IMF scar, I do whatever dissection is easy, posteriorly. First, it helps me pull down the breast tissue to do the anterior dissection and many people feel it makes the anterior dissection easier. Now the plan is to raise the anterior mastectomy flap up to the nipple area. Okay, that's fine.

What I'm doing here is feeling the thickness of the mastectomy flap, which is about 5 mm. Then divide these Cooper's ligaments up by the subcutaneous tissue. Particularly in the beginning and throughout, whenever the plane is not obvious, just gentle spreading identifies those Cooper's ligaments. Now we're gonna look at doing the dissection towards the nipple. We'll look at the color of the nipple which is nice and pink beforehand. And my dissection is up almost to the areolar border here. I'm gonna do it on both sides. I've already done the dissection on the medial side. Now I'm gonna do the lateral side.

CHAPTER 7

So now this part here starts to be the ductal tissue going to the nipple. So this is important. Once we get up to the under surface of the nipple area - I'm almost at the nipple. Then I spread on both sides to expose all of the ducts going up to the nipple. No cautery in this region. It usually separates quite easily actually. Grab the tissue that's going to the under surface of the nipple with an Allis clamp. I'm advancing the Allis to be closer because we're gonna get up to the dermis of the nipple. There you go. This is the under surface of the dermis of the nipple, there. And then this tissue is cut. There's the actual undersurface of the dermis of the nipple. I cut with Metz because it cuts very easily if you're not cutting the dermis. I find it's easier to put a suture in first on the anterior margin of the tissue behind the nipple. We lift up on that and then we take the biopsy somewhere between 5 mm to 7 mm. And this goes for frozen section for the tissue behind the nipple. This is the area of the dermis underneath the nipple. You can see inside the nipple there. And then this is subdermal in the nipple areolar complex because usually the breast tissue comes very close to the dermis in this area. Now we want to get back into the subcutaneous plane on both sides, which is really important. Before I divide the rest of the tissue, I'm gonna wait for this frozen section because right now I have all my landmarks and if I need to remove it, I know where that biopsy was done. And we're just gonna let the perfusion of the nipple restore itself, and I'm gonna dissect in another region now.

CHAPTER 8

[No Dialogue.]

CHAPTER 9

As we get closer to our marks at the sternal border, dissect more carefully and look for branches of the internal mammary perforator vessels or the associated anterior cutaneous nerves that often perforate nearby. There's a little vein right there, and the artery's usually in the same bundle. And it's perforating at this intercostal space. And if we look on the outside, it's right about here. You can see some branching. This looks like the nerve, which is the anterior cutaneous branch of the intercostal nerve, right there, which is clearly supplying this, which is the mastectomy flap right here, which is about 5 mm in thickness, 4-5 mm. You can see another one probably perforating right here. It's not necessary to dissect it out completely as long as we preserve it, but you can see that there's always a nice layer of fatty tissue around it. So we can remove all the breast tissue. In fact, here is the breast tissue, here. Here are some little branches going to the breast tissue that are gonna be divided while preserving the perforation here. And here is another little branch, here. This is a little branch of the vein, coursing over this direction. This is the breast tissue, which we have here, taking off the pectoralis. We're gonna divide this with cautery, removing the pectorals fascia right here. These are the branches of the IMP coming up here: vein and the artery is probably underneath there. And we showed the nerve before. So we know that that's preserved there. There's usually some little branches coming to the breast tissue that will bleed a little bit. That's the breast tissue. It can easily be divided with electrocautery and if we look closely, we can see that there's just a fatty plane, which is adjacent to the breast tissue that separates very easily posteriorly.

CHAPTER 10

This is the PEC block, the pectoris muscle. The serratus coming up to the muscle. Inject under the fascia of the serratus plane. Just under the pectoralis muscle. As you get higher, you start to see more of the pec minor muscle, which I can see way in there. But wherever the fascia's exposed, aspirate first and then inject.

This is the PECs 2 block between pec minor and serratus. Normally we're injecting with 0.25% marcaine with epi because it diffuses well. Here you can see the fascial plane under the pectoralis muscle. I lift it away from the chest wall either with a pickup or my hand and retract so that we're never injecting near the chest wall. The local anesthetic is injected. Here actually is pectoralis minor, and then this is pectoralis major. There's actually a few fibers of pectoralis minor, and this is pectoralis major. So under this fascial plane and pointing away from the chest wall, this is a PECs 1 block.

CHAPTER 11

I just demonstrated all of the key steps to preserve the important internal mammary perforator blood flow to the nipple areolar complex during nipple-sparing mastectomy. I showed that it could be accomplished easily through an inframammary fold incision, which is often the preferred incision for cosmetics. However, we adjust the incision based on the oncologic situation and the preference of the plastic surgeon. Also, we inject tumescence, which facilitates hydrodissection and separation of the fatty tissue from the glandular breast tissue. Also, I demonstrated the technique of doing a biopsy of the tissue directly behind the nipple. I showed how the undersurface of the dermis of the nipple is exposed. Then typically I prefer to divide the tissue with Metzenbaum scissors because it's difficult to cut the dermis with the Metzenbaum scissors. So it usually preserves the dermis. And you could see where all the ductal tissue was removed, and then the suture placed, and it was sent to pathology. The next step is to complete the anterior mastectomy flap dissection after the posterior dissection is done and most of the breast tissue and pectoral fascia is already removed posteriorly. Finally, I usually do near the end of the dissection the exposure of the internal mammary perforator vessels when we have maximum visibility on both sides. With gentle, very careful dissection in that area, we could see the internal mammary perforating vessels, where they come through the pectoralis, and they were preserved and left on the mastectomy subcutaneous flap. It was very easy to see the subcutaneous tissue that we usually see around those vessels and still remove all of the breast tissue and pectoralis fascia. At the conclusion of the procedure, the nipple areolar complex appeared well perfused. Also in this procedure, there was very nice exposure of the lateral cutaneous branch of the intercostal nerve, which sometimes I preserve if the plastics and reconstructive surgeon is planning to do nerve reinnervation, and those have been grafted to the under surface of the nipple to restore nipple sensation in some of our patients with promising early results.