Breast Reconstruction Perforator Flaps

Anatomy and Physiology

DIEP Flap

Surgical planning of the DIEP flap involves the evaluation of the skin of the lower abdomen. The blood supply to the skin and fat from the lower abdominal wall, which will constitute the flap, arises from the external iliac artery and runs from lateral to medial under the rectus muscle. The deep inferior epigastric artery (DIEA) describes its course from the lateral aspect of the rectus abdominis muscle to the umbilicus. It starts from the transversalis fascia towards the peritoneum, where it penetrates the posterior aspect of the rectus abdominis muscle and takes on a variety of branching patterns with an average of five perforators supplying the skin. Most of the perforating vessels are found within 2 cm cranial and 6 cm caudal and between 1 to 6 cm around the lateral aspect of the umbilicus.[7]

Perforators that pass through the rectus muscle at the level of the tendinous insertions are generally large with few side branches.

The innervation of the flap depends on dermatomes from the 11 and 12th intercostal nerves, with some contribution from the iliohypogastric and the ilioinguinal nerves.

SIEA Flap

The SIEA provides the same abdominal tissue for breast reconstruction as the DIEP flap, but no incision must be made in the abdominal fascia, and no vessel dissection is performed through the rectus abdominis muscle. However, less offered by the surgeon because the SIEA and vein are only inconsistently present on sufficient caliber to reliably support sufficient tissue for breast reconstruction. The anatomy of these vessels is quite variable and arises from the common femoral artery and saphenous bulb.

GAP Flap

Gluteal artery perforator (GAP) flaps allow the transfer of tissue from the buttock and are based on perforators from either the superior or inferior gluteal artery.

Introduced by Allen in 1993, recommended for women who have more skin and fat available in the buttock area than in the abdomen or who have had a prior abdominoplasty. No sacrifice of muscle is required.  The superior gluteal artery perforator (SGAP) flap and the inferior gluteal artery perforator (IGAP) flap can be used in these instances.   The superior gluteal artery arises from the internal iliac artery and exits the pelvis superior to the piriformis muscle. The inferior gluteal artery is a terminal branch of the internal iliac artery.  Typically the length of the IGAP pedicle is longer than that of the SGAP.  Between 2 and 4 perforating vessels from the inferior gluteal artery will be located in the lower half of each gluteal muscle.

Profunda Artery Perforator Flap

This reconstruction technique uses posterior thigh soft tissue based on profunda artery perforators and was first described by Angrigiani et al., who presented the transfer of posterior and medial thigh skin based on profunda femoris perforators.[8] The first profunda artery perforator flap was performed for breast reconstruction at the International Course on Perforator Flaps in Mexico City in 2010.

The posterior thigh tissue is bounded by the iliotibial tract and adductor muscles horizontally, and the gluteal fold and popliteal fossa vertically. The profunda femoris artery enters the posterior compartment of the thigh to gives three main perforators.

Indications

Oncologic considerations such as stage and BRCA mutation status play a key role in breast reconstruction. Patients requiring adjuvant radiation are often best served with autologous tissue reconstruction.  The lower abdomen skin and fat was discovered to be an ideal material for breast reconstruction. The DIEP  flap has also been used with excellent results for esthetic autogenous breast augmentation. In many clinical institutions, DIEP and SIEA (superficial inferior epigastric artery perforator) flaps have completely replaced the use of the free TRAM (transverse rectus abdominis myocutaneous) flap and constitute the first choice for autologous breast reconstruction. DIEP flap reconstruction may also be used for women with congenital or lumpectomy breast defects.[9]

The DIEP flap can be useful in the reconstruction of the head and neck, in particular in resections leaving a large defect such as in total glossectomy.

Other indications of the flap have been described for facial dysmorphisms such as Romberg's disease. Finally, by dissecting the deep inferior epigastric vessels to their origin, a pedicled DIEP flap will easily cover the perineum, the greater trochanter, the sacrum, and even the middle third of the thigh.

IGAP and SGAP flaps are used when abdominal tissue is unavailable.

The Profunda artery perforator flap is ideal for patients with a small to medium breast size and excess tissue in the posterior thigh.

Contraindications

Contraindications to Perforator flaps for breast reconstruction include the following:

• Severe lung or cardiac disease because this long-lasting procedure is not devoid of complications.
• Collagen vascular disease
• Obesity with BMI > 30
• Older patient  because age over 65 is an increased risk for a hernia after abdominally based surgery and thrombosis
• Active Smoker 
• Prior abdominal or thoracic surgery that has interrupted blood supply to potential flaps (for DIEP Flap and SIEA Flap)
• lack of availability of autologous tissue
• Prior radiation therapy to the donor site 
• Thrombotic diseases because they increase the risk of free flap failure
• Advanced breast cancer with metastatic disease 

Some may not consider all of these to be contraindications, but increased risk factors to be taken into consideration when reconstructive options are being weighed.

Equipment

Free flap reconstruction is a long, highly technical operation compared with a pedicled flap and requires a surgeon who has experience with microsurgery to re-attach blood vessels. Microsurgical equipment includes micro sutures (8-0 - 10-0), jeweler’s forceps, microscissors, a vessel dilator, a microneedle holder, microvascular clamps, microsurgical hemoclips, and a micro-instrument wipe.

To assess the blood supply to the abdominal wall and recognize the path of the most favorable perforators, Preoperative multi-dimensional computed tomography (CT) perforator mapping of the lower abdominal wall and three-dimensional reconstruction of the CT findings can complete the preoperative evaluation. Medical imaging has thus made it possible to reduce operative time and the rate of postoperative complications.

A duplex Doppler scan may be beneficial before reconstructive surgery. It collects detailed data and information regarding the location, size, and flow of perforating vessels, as well as information regarding the thickness and richness of adipose tissue. it can also give information about healing, the unusual trajectory of the vessel, and obstruction of the pedicle.

A hand-held Doppler and other options for bedside free flap monitoring are also necessary.  This includes the need for bedside staff experienced in free flap monitoring.

Personnel

The personnel needed for free flap breast reconstruction must meet a microsurgeon and an assistant, an anesthesiologist, circulating nurse, scrub tech, and qualified nursing staff is recommended for optimal monitoring of the flap and vital parameters postoperatively.

Preparation

Before any intervention, a consultation with an anesthesiologist is necessary in order to identify the factors of co-morbidity and to assess the feasibility of the operation. Establishing a general anesthesia program is necessary since you must keep an average blood pressure higher than 70 mmHg without having to resort to vasoactive agents such as catecholamines. For monitoring the flap vessels intraoperatively, the Doppler probe is mandatory.

Tissue oximetry using near-infrared spectrophotometry technology has been reported as a useful tool because it is non-invasive and objective and provides continuous monitoring with high sensitivity and specificity.[10]

Other techniques like fluorescent indocyanine green angiography (FA ICG) are used and are reliable adjuncts to assessing flow in the flap.[11]

Technique or Treatment

DIEP Flap

The patient is placed in a supine position, arm in abduction. Perforators can optionally be assessed with the pencil Doppler. A lower incision is made carefully to preserve the superficial inferior epigastric vein with the longest length possible.

The incisions are carried down to the abdominal fascia. Scarpa’s fascia is carefully maintained, and beveling is performed at the lateral aspects and at the level below Scarpa’s fascia only.

The flap is usually elevated from lateral to medial, and the search for perforators is begun when the territory of the rectus sheath over the lateral rectus muscle is reached. If bilateral flaps are being prepared, the midline incision can be made, and the flap traced from medial to lateral as well, to help surround the perforators. Larger perforators are identified, and a single flap can be supported on one major perforator. The umbilicus is separated from the flap with a periumbilical incision. When a large dominant perforator is isolated, the rectus fascia is incised longitudinally, around the perforator vessels, especially the vein can be quite delicate.  The fascia is opened for 10 to 12 centimeters, and the perforator is traced through the muscle. When the entire flap is isolated on the perforator, and DIEA/DIEV and the recipient area is ready, the DIEA and the venae can be ligated and divided.

Once all of the side branches are divided and the pedicle is free near its origin, The deep inferior epigastric vessels are clipped, and the flap is ready for transfer to the recipient region. Typically the anastomosis is technically easier with the contralateral lower abdominal flap because of the position of the artery and vein, as most people use the internal mammary vessels for inflow.[12]

Once the anastomosis is complete, the flap is allowed to perfuse for a short period of time and is inspected for arterial inflow and venous congestion. It is important to maintain the superficial inferior epigastric vein during shaping to be used as a second venous anastomosis in cases of venous congestion.

The flap may be secured in position with surgical staples, and the patient placed in a seated position to assess for symmetry.

The abdominal incision is closed in layers over suction drains with the hips flexed and knees bent in a semi-Fowler position. The umbilicus is brought through the abdominal wall and sutured into position.

SIEA Flap

The preparation of the recipient site is the same as described above for the DIEP flap.  During flap harvest, the superficial inferior epigastric vessels are approached first, and if the caliber of these vessels is sufficient (1 to 1.5 mm)  at the level of the inferior flap incision, they are followed down to their origin from the common femoral artery and saphenous vein. Since the vascular pedicle of the SIEA flap is typically smaller than that for a DIEP flap, using a smaller perforating branch of the internal mammary vessels is recommended.

SGAP Flap

The Doppler probe is used to end perforating vessels from the superior gluteal artery, found in one-third of the distance on a line from the posterior superior iliac crest to the greater trochanter. The skin paddle is marked in an oblique pattern from the inferior medial to the superior lateral to include these perforators.  

IGAP Flap

The gluteal fold is noted with the patient in a standing position. Doppler probe used to end perforating vessels from the inferior gluteal artery. The internal mammary vessels are preferred as anastomosis to these vessels, especially important for the SGAP flap, which typically has a shorter pedicle than the IGAP flap. The artery and vein diameters for anastomosis are 2.0 to 2.5 mm and 3.0 to 4.5 mm, respectively. The skin and fat overlying the gluteus maximus muscle are elevated superiorly and inferiorly to allow solid approximation of the fascia of the donor site.

Profunda Artery Perforator Flap

To identify key perforators and to assist in determining the amount of tissue available for reconstruction, all patients undergo magnetic resonance or computed tomographic angiography preoperatively.

The patients are placed supine in a frog-leg position with the thighs abducted. The surgeon incises the medial part of the thigh and continues up with deep fascia. A perforator-based flap is then elevated from medial to lateral just posterior to the adductor longus muscle, with the gracilis muscle reflected anteriorly, the adductor magnus fascia is entered. Dissection proceeds posteriorly until key perforators are identified.

The dissection of the pedicle can proceed to its origin at the profunda vessels If more length is needed. Once vascular microanastomosis is performed with the internal mammary vessels, The flaps are coned for inset to recreate the desired breast shape and contour.

Complications

Microvascular free tissue transfer is a reliable method for the reconstruction of complex surgical defects, with success rates ranging from 91 to 99 percent.[13]

Although the DIEP flap achieves long-lasting satisfactory results in most patients, this long-lasting procedure is not devoid of serious complications. Obesity is a major predictor of the flap and donor-site complications, and these patients must be properly informed of the risks of the intervention and must be advised beforehand. Similarly, neoadjuvant preoperative chemotherapy and prior abdominal surgery increase the rates of minor complications.

Higher incidences of partial and fat necroses have been reported with the deep inferior epigastric artery perforator (DIEP) flaps than with the transverse rectus abdominis musculocutaneous (TRAM) flaps (Wang, Liu, Song, & Wang, 2014). The technological advancements in magnification, suture material, and surgical instruments and increasing surgical experience with microsurgery may play a role in the occurrence of these complications.[14]

Vascular occlusion with total or partial flap loss is an unavoidable potential complication of microvascular surgery.[15][16]

Other Perforator flaps complications include infection, wound dehiscence, fat necrosis, hematoma, abdominal wall laxity/hernia, transient brachial plexus injury, deep venous thrombosis, mild congestive heart failure,  pulmonary embolus, blood loss,  pain, and weakness at the site from which the donor tissue was taken.[15]

Obesity is considered the major risk factor of bulging and hernia after harvesting free abdominal flap.[17]

 A rise in intra-abdominal pressure or the presence of a weak abdominal wall (high body mass index, multiple scars on the abdomen), or a history of active smoking increases the risk of developing abdominal bulging or asymmetry.

Predictors of increased flap morbidity were smoking, chemotherapy, pre reconstruction radiotherapy, post-reconstruction radiotherapy, hypertension, diabetes mellitus, abdominal scarring, obesity, age, flap size, number of venous anastomoses, and number of perforators.[18]

If choosing the mammary arteries, there is a small risk of pneumothorax.

Clinical Significance

Free tissue transfer has become the standard of care for the reconstruction of complex defects. For those patients who request autologous reconstruction, those who have adequate tissue for reconstruction, and those medically acceptable for surgery, the use of the DIEP flap can be an excellent option for breast reconstruction and allows for a breast with a natural appearance and texture because better cosmesis can be achieved with skin and soft tissue, and there is no sacrifice of the abdominal musculature which has led to a marked decrease in the hernia rate.[18]

In the literature currently, there are large-scale controlled studies on the use and beneficial effects of the DIEP flap in breast reconstruction. These investigations include randomized controlled trials (RCTs), observational trials, and many case series.

To evaluate the success of the free flap, a recent retrospective study was performed, including 965 DIEAP flap breast reconstructions in 739 patients with 444 unilateral and 295 bilateral cases.[19] the author concludes that numerous possible causes are leading to revision. This cause can be either mechanic (wrong pedicle, poor anastomosis technique,…) or intrinsic (bad perfusion, bad coagulation, comorbidities,…), and anesthesia time does not predict the need for revision surgery.

 As to the long-term effectiveness of the DIEP flap for breast reconstruction, controversies exist, for example, in a recent retrospective analysis including a total of 3,310 cases, corresponding to 15,991 abdominally based unilateral immediate breast reconstructions. National data were collected to determine the differences in total hospital costs, length of stay (LOS), and early postoperative complications after free TRAM (fTRAM), right transverse pedicled myocutaneous flap of the abdomen (pTRAM), deep inferior epigastric perforator (DIEP), and superficial inferior epigastric artery perforation flaps (SIEA), the authors found that fTRAM, DIEP, and SIEA flaps incur higher hospital total charges, have longer lengths of stay, and experience more immediate complications compared with pTRAM.[20]

For many authors, DIEP flaps exhibit fewer complications related to flap ischemia and donor site morbidity. This remains to stay unclear to other authors:

A literature search of articles published between January 1, 1990, to January 1, 2017, was performed in a meta-analysis by Woonhyeok et al., including Eleven articles comparing pedicled TRAM (pTRAM) flaps with either free TRAM (fTRAM) or DIEP flaps. No difference was observed concerning which flap-type was most beneficial regarding flap vascularity and donor site morbidity.[21]

Several techniques have been used to reduce the incidence of flap necrosis. The most popular is the one using Indocyanine Green Angiography.[22]

 In a recent study published by Austin Hembded in July 2020,  Indocyanine green angiography was used, and a retrospective review was performed on 1000 free flaps for breast reconstruction. The author concluded that intraoperative indocyanine green fluorescence angiography decreases the odds of fat necrosis, saves volume when flap trimming at inset, and can significantly reduce the postoperative surveillance burden in DIEP-based breast reconstruction.

Although the DIEP flap remains the first choice for breast reconstruction, some patients are excluded from this choice due to insufficient donor tissue volume, previous abdominal surgery, or aversion for the abdominal scar at the donor site. When the abdomen is not a potential donor site, other sites must be considered. The profunda artery perforator flap is an excellent option for breast reconstruction with a high success rate and a low complication rate.  The SGAP flap represents an alternative for autologous breast reconstruction when DIEP is not available, particularly in patients with a low BMI because the donor site usually has enough tissue.[23]

Enhancing Healthcare Team Outcomes

The interprofessional approach and multidisciplinary management are necessary for the treatment of breast cancer to increase optimal patient care and satisfaction and minimize risks and complications.

Collaboration and team spirit are necessary between the surgeon and the oncologist in order to establish an optimal clinical path for quality care because the skin incision must be revised by both teams so that the resection can be both with healthy margins and therefore oncological and as cosmetic as possible to satisfy the patients. Radiotherapists are also included in the care team because they must organize and plan the radiotherapy and chemotherapy sessions before breast reconstruction.

Nursing, Allied Health, and Interprofessional Team Interventions

The qualified nursing staff is recommended for either perioperative or postoperative management to monitor free flaps and alert the plastic surgeon in the event of any abnormalities.

Nursing, Allied Health, and Interprofessional Team Monitoring

In plastic surgery centers specializing in DIEP flap breast reconstruction, intensive monitoring is crucial after breast reconstruction using a free flap because signs of deterioration of the flap can appear quite early. Sometimes, suddenly and detection of its signs allows recovery of the flap within an acceptable timeframe.

In recognized university centers, the creation of a universal protocol for monitoring postoperative flaps is recommended to guarantee quality nursing care. Nurses must be more confident in their ability to manage postoperative complications and be able to contact the surgeon in the event of anomalies or under prescription.