Total breast reconstruction by external vacuum expansion (EVE) and autologous fat transfer (AFT)

Introduction

Breast reconstruction continues to evolve and has come a long way from having prosthetic implants as the sole option. Since the early 1980s, the pedicled transverse rectus abdominis muscle (TRAM) flap and its microvascular free flap refinement gave patients another option of totally autologous tissue breast reconstruction. These flaps highlighted the long-term benefits of using vascularized fat for breast reconstruction. This chapter is about a third option, introduced early in the twenty-first century, which provides another alternative that allows women to pursue breast reconstruction without using the traditional options of flaps or implants.

Total breast reconstruction by autologous fat transfer (AFT) and external vacuum expansion (EVE) is a minimally invasive alternative method of autologous breast reconstruction. AFT + EVE has the potential to restore aesthetically pleasing breasts that often feel and look just like the lost originals. A benefit of this reconstruction is that near normal return of sensation has been observed in many patients.

To reconstruct an entire breast with fat graft, a large amount of avascular tissue has to revascularize in order to survive. Two factors restrict the amount of graft that can be successfully transplanted as 3D tissue droplets into a mastectomy defect: the mechanical compliance of the skin and the limited capacity of the recipient to stretch in order to accommodate the graft. Unless it is prepared preoperatively, normal skin can only stretch a limited amount. This hampers our ability to turn a flat mastectomy defect into the tear drop contour of an aesthetically pleasing breast. We therefore need to pre-expand the skin to gain the necessary surface area. But solving the skin surface issue is not enough, because pumping fat under a loose skin flap with nothing underneath will create a collection cavity. To revascularize and survive, each individual avascular fat graft droplet needs to come into intimate contact with a well-vascularized 3D nutritive scaffold. The mastectomy recipient tissue scaffold therefore also needs to be enlarged to accommodate the mega volume of fat graft needed to restore the breast mound. Fat is not an expander and this is probably the reason why AFT alone has not been very successful at reconstructing the breast. To succeed, fat grafting needs the help of an expander capable of enlarging both the recipient scaffold and the skin surface.

EVE is a necessary adjunct to mega-volume fat grafting to the breast ( Fig. 50.1 ). By pulling from the outside, EVE stretches the flat mastectomy skin to expand its surface into a dome, and it induces the underlying fibrovascular tissue to enlarge as it follows the rising skin surface. Appropriate preparation with EVE, therefore, not only generates the necessary skin envelope, it also creates in situ the “holy grail” of tissue engineers: a 3D graft recipient scaffold that is intrinsically vascularized and innervated. Judicious seeding of that prepared scaffold with autologous lipoaspirate is in vivo tissue engineering. Our patients achieve this today without any additional scars and with the potential benefit of body contour improvement through liposuction.

The downside to this technique is that it takes longer than traditional reconstruction as it requires a few small outpatient procedures spaced a few months apart. Patients need to understand that they are growing back their lost breast and that this cannot happen overnight. In our extensive experience we found that it takes 1–1.5 years to restore a satisfactory breast mound. The number of operations varies between two and six sessions with a median of four operations. While some might see the number of operations as a problem, most of our patients who have gone through the trauma of mastectomy accept this as the less invasive ideal restoration alternative. When asked about their experience with this technique, most of our patients report that they underestimated the whole procedure, but that they would undertake the effort for a second time if they had to. Furthermore, it should be recognized that even if totally successful, the alternative of major surgery with vascularized flap transfer or with implants is rarely ever a single-stage operation. Studies that have reviewed traditional techniques have demonstrated that most patients require four to six touch-ups and revisions to complete their reconstruction.

Both authors of this chapter are experts in microvascular free flap breast reconstruction and feedback from their patients convinced them to switch techniques. We have a series of 10 patients who had their first mastectomy reconstructed with a microvascular free flap, and later, for their contralateral mastectomy, chose to reconstruct their second breast with EVE + AFT. They all report that they prefer their AFT breast over their breast reconstructed by a microvascular flap. They report that the fat-grafted breast felt more like the original lost one.

Patient compliance with use of the EVE device before and after the operations is also demanding. They need guidance and support from the surgeon or from a dedicated nurse during that process. However, educated patients admit that while appropriate EVE usage requires personal investment in time and effort, they would opt again for this method of reconstruction.

Our cost-effectiveness analyses also show that the costs between implant-based reconstruction and AFT-based reconstruction are similar, initially; however, in the long run, AFT comes at a lower price if we take into account the significant potential complications of implants and their need to be replaced over time. Furthermore, because they are performed in outpatient facilities, AFT-based reconstructions are also more cost-effective than the in-patient flap procedures and their often-required revisions.

In this chapter we describe the indications, contraindications, principles, technique, and the pearls and pitfalls of this technique.

Indications

This technique has the potential to regain sensate and natural-feeling breasts without undergoing the extensive flap surgery that requires hospitalization and several weeks of rehabilitation. Due to the complexities associated with autologous and prosthetic-based reconstructions, such as flap failure, BIA-ALCL and breast implant illness, it has been our observation that more patients are looking for alternatives to these traditional techniques.

Many of our AFT reconstruction patients have already suffered from extensive scarring from previous failed reconstruction efforts or have experienced significant tissue damage from radiotherapy. AFT is the slow, staged, and (in the authors’ opinion) safer salvage alternative. However, patients have to understand that this process is time-consuming and is a requirement for their journey towards breast restoration.

The inability or the unwillingness to wear the EVE is one of the key elements that will lead to an increase in the number of operations needed to complete the reconstruction. Properly informed patients understand that the more they comply with EVE, the more expanded their breast will be at the time of grafting. With better expansion, more fat graft will survive causing their breast to grow more with each grafting session. Better compliance will therefore reduce the number of sessions required to achieve their desired outcome. In order to prevent patients from going into a reconstruction without being properly informed about the EVE requirement, we ask them to wear the EVE in the office for a while so they get to know the device and to reassure them that it is painless. From our clinical experience, we have found that most informed women would rather bear the inconvenience of EVE for a few hours a day over a few weeks than to subject themselves to the traditional surgical alternatives.

Most patients will accept this when properly informed; however, some patients will decline this method of reconstruction from the beginning. In our experience, approximately 5% of women did not complete their reconstruction because of the difficulties with EVE.

The ideal patient for this procedure:

• 1.

  Is not irradiated. Although we treat many irradiated patients, we warn them that they will require at least 2–3 additional grafting sessions to reverse the radiation-induced tissue damage.

• 2.

  Has had a bilateral mastectomy, or does not mind some symmetrization procedure on the contralateral side.

• 3.

  Has no extensive scars due to previous operations or infections. While many of our patients come to us after implant or flap failure, the resultant tethering scars are difficult to release and require additional grafting stages.

• 4.

  Has ample amounts of fat. Although for the low body mass index (BMI) patients we have refined techniques that allow us to harvest a thin layer out of a wide surface, the harvesting is more time-consuming and needs to be more meticulous to avoid donor site contour defects. Nonetheless, we have very rarely turned down patients for being too thin.

• 5.

  Does not wish a reconstruction by flap surgery. Wishes to avoid a major surgery with potential donor site morbidities.

• 6.

  Does not want silicone or foreign materials in her body.

• 7.

  Is compliant and well informed.

• 8.

  The procedure is ideally suited following prophylactic mastectomy in women at high risk of breast cancer. For these patients, AFT + EVE has the potential to reconstruct a new breast that feels and looks like the original.

Contraindications

The list of contraindications is relatively short. The only absolute contraindication for autologous fat grafting is tobacco use. Under no circumstance are active smokers are accepted.

Relative contraindications are anticoagulants that have to be bridged or stopped prior to the surgical procedure. Vitamins, herbs or other supplements that tend to prolong bleeding time should also be discontinued at least 2 weeks prior to surgery. Extravascular bleeding from cannula passage competes with the fat for the limited interstitial graft recipient space.

Patients that are suspected of non-compliance with EVE should also be seen as a relative contraindication.

Fundamental principles and basis for the technique

The primary pitfall for AFT is when the untrained surgeon injects a large volume of fat obtained by liposuction into the recipient tissue. This is one of the main misconceptions about lipofilling. Although harvesting and grafting with a syringe and a cannula might seem like a simple procedure, it is of paramount importance to adhere to the fundamental principles.

Fat delivered in large clumps into the subcutaneous layer is destined to fail. The fat has to be transferred as tiny droplets well surrounded by recipient tissue in order to maximize the graft-to- recipient interface contact that is crucial for revascularization and survival of the transplanted fat. The tissue surrounding the transplanted fat droplets has to provide for neoangiogenesis that builds bridges between the recipient circulation and the capillaries in the transplanted tissue to revascularize it and allow it to survive. This principle is well known and was described more than 120 years ago by Neuber.

Yoshimura elegantly described three zones in a grafted fat particle: the thinnest outermost survival zone, the intermediary 1–1.5-mm regenerative zone and the deeper necrotic zone (see Chapter 4 ). Droplets larger than 3 mm across (or larger than 17 μL) range are doomed to have a central necrotic area. And since we typically graft by delivering ribbons while retracting the cannula, the ribbons should not be wider than 3 mm and individual ribbons should not coalesce into larger ones.

The final surgical outcome depends upon a succession of chain-linked steps that need to be individually optimized. A chain is as strong as its weakest link and that weakest part seals the fate of the procedure. It is important to grasp this rate-limiting step concept. The analogy of fat grafting to planting seeds in a field is appropriate here. In order to get a successful crop, the farmer has to obtain good S eeds, properly S ow them in a well-prepared, large enough S oil, and S upport the seedlings in order for them to survive. We call these the four “S” of Success. Similarly, to succeed with large-volume fat grafting, surgeons also need to carefully attend to each of these four steps because each of them can be the rate-limiting factor. Results will only improve by improving the bottleneck factor, not by improving non-rate limiting factors. Investing in getting the very best seeds, such as stem cells for instance, and planting them in a tiny, rocky recipient site will result in a poor yield. Similarly, excellent seeds dumped in a corner of a very large and well-fertilized field will also result in a poor yield. It is important to recognize that investing to maximize a non-rate limiting step is just as futile as adding horsepower to a car stuck in traffic. Most of the fat grafting literature focuses on the seeds, the harvesting techniques, the graft preparation alternatives and the many potentially beneficial additives. However, none of these have proven significantly superior because in mega-volume fat grafting, the grafting material is not a rate-limiting step. There are other more rate-determinant steps that determine the outcome such as the size and quality of the recipient capable of accepting the mega-volume grafts, as well as the craftsmanship of the surgeon in meticulously delivering the graft such that each tiny fat particle lies in perfect contact with the recipient hosts cells.

Basic concepts of fat grafting

There are several publications in the medical literature that focus on fat graft survival with variable outcomes. In some publications, fat retention is reported to be as high as 70% or 80%; however, this should not be considered as realistic in large-volume augmentation. With ideal grafting conditions, the maximum percentage augmentation with revascularized live fat rarely exceeds 50%. This is typically reached at the peak of the recipient capacity to accept the graft. Grafting beyond recipient capacity is counterproductive. However, we keep arguing that true percentage graft survival is a difficult number to derive. Since we cannot count fat cells, the number in the numerator depends upon how loose or compacted the graft material used. More importantly since the desired outcome is tissue augmentation, a more relevant measure of success would be percentage augmentation.

The surgery