Deep Inferior Epigastric Perforator Flap: Microvascular Anastomosis and Neurotization

Procedure: This video depicts the microvascular anastomosis of the deep inferior epigastric artery and vein to the internal mammary artery and vein in an anterograde fashion for a delayed bilateral deep inferior epigastric perforator (DIEP) flap reconstruction in a 53-year-old female patient status post bilateral mastectomy for breast cancer. Introduction: The DIEP flap is an autologous form of breast reconstruction following mastectomy. After abdominal flap dissection and recipient internal mammary vessel harvest, the contralateral abdominal DIEP flaps are anastomosed with recipient vessels and nerves. Indications/Contraindications: DIEP flap breast reconstruction is recommended in patients who wish to achieve breast reconstruction with autologous tissue and have suitable abdominal donor tissue. It is also  considered a preferred method of reconstruction for patients who have undergone radiation. Absolute contraindications include previous abdominoplasty and high-risk medical comorbidities, with elevated BMI, smoking and advanced age considered relative contraindications. Materials and Methods: Pre-pectoral tissue expanders were removed with a total capsulectomy, and the internal mammary vein and artery were exposed after pectoral division and cartilaginous 3rd rib removal. Contralateral abdominal DIEP flaps were simultaneously harvested. Venous anastomosis between the deep inferior epigastric (DIE) vein and internal mammary vein was facilitated through use of a venous coupler. Arterial anastomosis between the DIE artery and internal mammary artery was achieved through handsewn, simple interrupted sutures. Neurotization of the flap was performed by coaptation of the 4th intercostal nerve to a sensory nerve of the abdominal flap via cadaveric nerve graft. Results: Bilateral abdominal DIEP flaps were anastomosed to the contralateral internal mammary arterial and venous counterparts. Neurotization of the flaps was achieved with cadaveric nerve grafts. Conclusion: This report demonstrates how to perform the critical microvascular anastomotic and coaptation steps for a neurotized DIEP flap.

Purpose of technique: According to the American Cancer Society, 1 in 8 American women will develop breast cancer in their lifetime. 1 Following mastectomy, many women will consider breast reconstruction. Since the introduction of the Women’s Health and Cancer Rights Act, published trends show an increase in post mastectomy breast reconstruction among US women from 12% in 1998 to 36% in 2011. 2 The Deep Inferior Epigastric Perforator (DIEP) flap has now become the most common autologous approach to breast reconstruction. It provides a large volume of soft, malleable tissue that resembles the natural consistency of the breast and allows patients to achieve breast reconstruction in one procedure, as compared to tissue expander reconstruction. It is the flap of choice for autologous breast reconstruction because it combines a long pedicle with a relatively straightforward dissection, minimal donor site morbidity, and improves the donor site contour. Microvascular anastomosis is the critical step of DIEP flap breast reconstruction. It serves as a model that can be applied to numerous surgical settings in free vascularized tissue transfer. Proper patient/case selection (indications): Patients considering breast reconstruction post mastectomy have choices of implant-based and autologous methods. Autologous reconstruction is typically favored in patients who have undergone mastectomy flap radiation. However, patient choice is key in the decision making after thorough surgeon-patient discussion.  In an evaluation of patient motives when considering implant versus autologous reconstruction, women seeking implant based reconstruction were more focused on surgical aspects including recovery time and surgical scars, while those considering autologous DIEP flap were more concerned with regaining a breast most resembling their prior breast consistency.3 A study of over 300 women who underwent breast reconstruction concluded that women who underwent autologous breast reconstruction were more likely to be younger (40 -49 years old) and overweight with no significant differences based on race, ethnicity, education or income. 4 Patient selection for DIEP flap also favors patients with minimized comorbidities who can withstand a more lengthy surgery. Contraindications (absolute and relative): Absolute contraindications to DIEP flap breast reconstruction include prior procedures that would compromise abdominal flap integrity including abdominoplasty and large transverse or oblique incisions. Prior abdominal liposuction is not an absolute contraindication, but a preoperative computed tomography should be performed to identify usable perforators. Free flap surgeries typically require a prolonged anesthesia time, therefore patients should generally be in good health and/or medically cleared for surgery by their primary care provider.  Age is not a contraindication to surgery, though patients under the age of 80 are preferred. 5 BMI >35 is a relative contraindication. Aspirin and herbal medications, which can inhibit platelet function and clotting, should be discontinued 3 weeks prior to surgery. 5 Active smoking is associated with an increased risk of multiple complications, including fat necrosis and abdominal wound dehiscence.  If possible, smokers should refrain from smoking for 3 months prior to surgery. In the senior author’s practice, all patients who are smokers are nicotine tested prior to surgery. Advantages and disadvantages over alternative techniques: In a study of patients who underwent postmastectomy breast reconstruction, DIEP flaps were found to have the greatest overall satisfaction when compared to tissue expanders / implants, latissimus dorsi pedicled flaps and transverse rectus abdominus muscle (TRAM) flaps.6 While implant-based and autologous reconstructions were found to have similar aesthetic outcomes short-term, autologous reconstruction was deemed more aesthetically favorable in long term outcomes (>8 years postoperatively). 7 The cost of a DIEP flap is initially higher than implant-based reconstruction, however, this cost diminishes over time with multiple clinic visits for tissue expander fills and subsequent surgery for implant exchange. Disadvantages of the DIEP flap procedure compared to implant-based reconstruction include longer operative time and initial recovery period, additional donor site morbidity and risk of flap necrosis requiring additional surgery. These disadvantages are particularly notable in high risk patients: elderly (>60 years old), advanced disease (AJCC 7th edition stage III or IV), any comorbidities (Charlson score / Deyo Modification) or use of pre- or post-mastectomy radiotherapy with a larger growth in implantation-based reconstruction in recent years. 8 Furthermore, nonirradiated chests were associated with better breast sensation post implant reconstruction, while irradiated breasts were found to have better sensation levels post DIEP flap reconstruction.9 This may change with newer resensitization techniques. Complications and risks:  DIEP flaps have complications related to the surgery as a whole, as well as specific complications related to the chest dissection and the abdominal dissection.  Specific risks of the chest dissection include hematoma, seroma, pneumothorax, as well as complications related to the flap microvascular anastomoses including venous congestion, marginal necrosis / fat necrosis, and partial / total flap loss. Some of the other complications related to the surgery include abdominal donor site complications, deep vein thrombosis (DVT), and pulmonary embolism (PE).

Instrumentation: Standard surgical instruments were utilized including bipolar electrocautery. An intraoperative Doppler was utilized for perforator identification. In addition, free tissue transfer required standard microsurgical instruments, including microsurgical scissors, forceps, and needle holders. A venous coupler was used for venous anastomosis. Depending on surgeon preference, there are various techniques that may be used for intraoperative assessment of flap perfusion, ranging in cost from clinical assessment of capillary refill, thermal imaging, to indocyanine green angiography. Postoperative monitoring techniques also largely vary based on surgeon preference. In the senior author’s practice, clinical assessment is typically sufficient, though implanted Doppler probes and flap pulse oximetry (Vioptix) may be used at higher cost. Setup: The chest midline, from sternal notch to xyphoid process was marked, in addition to the inframammary fold. Surgical team was divided in two: (1) Abdominal Dissection and (2) Chest Dissection, working simultaneously to prepare the flap and recipient vessels. Preoperative workup: Preoperative workup included a reconstructive consultation focused on patient oncologic history and treatment plan (including but not limited to tumor biology, staging, chemotherapy, radiation), comorbidities, and desired outcomes. Physical exam evaluated mastectomy flaps, since delayed, as well as donor sites for scarring and appropriate volume. Review of patient’s prior imaging (mammography, ultrasound, MRI) may prove useful to understand prior tumor location. Patient may need initial “babysitter” tissue expander placement prior to DIEP flap reconstruction to preserve the mastectomy pocket. All patients at our institution received pre-operative abdominal CT angiogram for planning and perforator selection. The largest dominant perforator(s) are selected based on imaging. Perforator selection is also influenced on whether the DIEP flap is a unilateral or bilateral as well as intraoperative doppler assessment, palpability and visual inspection prior to final selection. Flaps are ideally based on a single dominant perforator, however, if there is any question about vascularity, intra-operative imaging can be utilized for assessment and additional perforators included if needed. Anatomy and landmarks: The 3rd rib was identified bilaterally by palpation, and the overlying pectoralis muscle was divided through small, electrocautery incision. The internal mammary vessels originate from the proximal subclavian vessels, and run along the anterior chest wall, supplying the breast and anterior chest. Bilaterally, the internal mammary (IM) arteries are found approximately 1-2 cm lateral to the sternal margin in between the intercostal muscles and cartilaginous rib cartilage anteriorly and the transversus thoracis muscle posteriorly. Detailed steps to procedure: The patient had a delayed breast reconstruction following bilateral mastectomies with pre-pectoral tissue expanders (TEs) previously placed. The pre-pectoral TEs were removed with a total capsulectomy. The pectoralis major muscle was next divided in the direction of its fibers over the 3rd rib. This was divided cephalad along the sternal insertion in an ‘L’ fashion in order to expose widely the cartilaginous 3rd rib. The 3rd rib perichondrium was next incised, and the cartilaginous 3rd rib was removed using a freer elevator and rongeur. The internal mammary vein and artery were exposed, and the adventitial attachments were next cleaned off.  While not depicted in this video, a method for internal mammary vessel preparation has been described and filmed by Haddock and Teotia. 10 It can be found at this link: https://journals.lww.com/plasreconsurg/Fulltext/2017/11000/Five_Steps_to_Internal_Mammary_Vessel_Preparation.3.aspx Once the internal mammary vessels were cleaned off, the  contralateral abdominal DIEP flap was harvested. The pedicle was marked using a surgical marker to help identify the proper lay of the vessels and to prevent twisting. The flap was fixed in place using a saline soaked laparotomy sponge ‘hammock’, which was secured to the patient. The flap pedicle was then oriented correctly using the previous markings and the flap artery was flushed with heparinized plasma until the effluent from the pedicle vein was clear. Heparinized plasma was also used to allow for adventitial hydro-dissection to facilitate DIE vessel separation using micro scissors. Curly microvascular clamps were applied to the internal mammary artery and vein, and then each was divided. The ends of the deep inferior epigastric vessels and internal mammary vessels were approximated without kinking of the pedicle. The deep inferior epigastric vein and internal mammary vein were then dilated and a vein sizer was utilized to determine the size of coupler to be utilized. The internal mammary vein and DIE vein were irrigated with heparinized saline. A 4.0 mm coupler was utilized to anastomose the veins in an antegrade direction. The DIE vein was first placed on the coupler, using a ‘hockey stick’ in order to appropriately place the vein intima over the spikes of the coupler. The vein wall was draped evenly over the spikes of the coupler and the spikes traversed the full thickness of the vein wall in order to avoid kinking of the vein or endothelial defects. The internal mammary vein was then positioned on the opposite end of the coupler and both lumens were irrigated with heparinized saline prior to closing the coupler. A mosquito hemostat was used to ensure the coupler was fully closed. Next, attention was brought to the arterial anastomosis. A spurt test was performed to assess patency, and the artery was coated with a vasodilator (papaverine, calcium channel blockers, or local anesthetic) to reduce spasm. Adequate adventitial stripping was ensured. The vessels were irrigated with heparinized saline. The vessel borders were then carefully approximated and hand-sewn with 9-0 Nylon simple interrupted sutures. The 3 and 9 o’clock sutures were placed first in order. A tail was left on the sutures to facilitate vessel wall manipulation without grabbing the vessel wall with jewelers. Additional sutures were placed on the anterior and posterior arterial wall in order to ensure no intimal leaks. Suture bites and instrumentation was performed nearly entirely with the fingertips with only a small input from the wrists. Care was taken not to put traction on the vessel, as tear or trauma to the vessel intima could lead to thrombosis. All non-traumatic microvascular clamps were removed from the cephalad internal mammary vein and artery and the flap was allowed to reperfuse. If necessary, the superficial inferior epigastric vein (SIEV) or a second deep inferior epigastric (DIE) vein could be anastomosed to the internal mammary vein (retrograde). Otherwise, the internal mammary vessel retrograde stumps are clipped. Neurotization of the DIEP flap was next performed. The fourth intercostal nerve was identified parallel to the intercostal muscle fibers during the IM vessel dissection. This was clipped previously for identification and transected. The medial end was utilized and sutured to a 2mm x 70mm nerve allograft using a nerve conduit with 8-0 Nylon suture. A GEM clip was utilized in order to help obliterate excess opening of the nerve conduit. The cadaveric nerve graft was then connected to the contralateral side of the nerve conduit. The other end of the cadaveric nerve graft was connected to an unnamed sensory nerve of the DIEP flap. This was equally connected using a nerve conduit in a similar fashion to the first nerve coaptation.

The optimal DIEP flap anastomosis consists of properly joined and patent arterial and venous vessels with suture line eversion, minimal tension and direct intima to intima contact. This allows for successful reperfusion of the flap. The flap should have appropriate cutaneous capillary refill that is not too brisk, display an appropriate doppler signal and be warm to touch, without signs of venous congestion. The flap should provide sufficient volume to fill the breast cavity. A risk and negative outcome of this procedure is venous congestion. The incidence of venous congestion post DIEP in the literature varies from 3-27% depending on inclusion criteria. 11 Venous congestion may result in longer operative times if recognized intraoperatively, or may require additional surgery, even resulting in flap loss.

Critical steps of the procedure: The critical step of this portion of the procedure is the technical anastomosis of both the internal mammary artery and vein to their flap counterparts. This is facilitated through proper evaluation of flap and recipient vessels size and quality, repeated assessment of vessel patency through heparinized saline flushing, proper sizing and selection of a venous coupler, utilization of a vasodilator to minimize spasm and careful handling of the vessel walls to minimize intimal damage as a potential nidus for thrombus. Another critical decision is identification of flaps that rely on the superficial system and the need for SIEV anastomosis in addition to the DIE system. Common modifications:  In this case, a single end-to-end anterograde anastomosis was performed. If a single DIEP flap does not create sufficient volume, a second flap (also known as a stacked DIEP) may be utilized. If the flap is not adequately perfused by one perforator, the cephalic extension of the flap pedicle may be connected to caudal mammary internal artery to be perfused in a retrograde fashion. Common pitfalls: Common pitfalls include failure to perform measures to prevent and recognize intraoperative signs of possible venous congestion, a complication that could lead to partial or complete flap loss. Troubleshooting of the technique(s): If venous congestion is suspected, differentiating global versus localized congestion can guide management. This can be facilitated by assessing cutaneous capillary refill, bleeding at flap edges, performing a gentle Acland (vessel strip) test, utilizing Doppler or thermal imaging to assess venous flow. 11 Limitations of the technique: At times, the internal mammary vessels may not be suitable and alternatives need to be sought. Options include the thoracodorsal vessels, thoracoacromial vessels, contralateral internal mammary vessels, cephalic vein turnover, or external jugular vein. Potential further applications of the technique(s): The techniques utilized in this procedure can be applied to any microvascular anastomosis. Knowledge of how to perform this procedure is very useful to any reconstructive or aesthetic surgeon as post-mastectomy autologous breast reconstruction continues to grow.

There was no funding for this project and the authors have no financial disclosures or conflicts of interest.

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