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29 Tissue Expansion During Abdominal Wall Reconstruction
311
wall fascia. In 1989, Byrd et al. described the fi rst interfascial expansion by placing the expander between the internal oblique and transversus abdominis. However, this technique has been largely abandoned because the expander is not placed on a rigid platform and expansion will occur both outward as well as inward [ 9 ]. Bidirectional expansion will be less effective in expanding the desired tissue (abdominal wall fascia/external oblique) and can increase the intraperitoneal pressure unnecessarily. As a result, defects in the abdominal wall fascia are treated with various abdominal hernia repair techniques such as component separation. Those techniques are discussed in other chapters.
In addition to increasing the volume of skin, tissue expanders can incite a fi brous reaction that interposes an additional connective tissue layer on the anterior abdominal wall. This vascularized capsule, combined with any existing anterior rectus sheath can be used to reconstruct abdomi­nal wall defects [ 3 ]. The use of prosthetic mesh in conjunction with tissue-expanded skin provides a durable abdominal closure and is technically simpler than fl ap closure methods [ 10 ]. Donor site morbidity is minimized relative to musculo­fascial techniques. Tissue expansion even allows excision of unsightly scars and skin grafts while providing excellent color and texture match. It also provides well-vascularized skin and soft­tissue coverage over the prosthetic mesh [ 10 ].
Techniques of TE for Abdominal Wall Reconstruction
There are wide varieties of expanders differing in shape, texture, and expansion mechanism. Selection of expanders and placement of expander should be tailored to the individual defect. Preoperatively, the surgeon must take into consideration previous scars, postoperative scars, fl ap movement in relation to the defect, and potential distortion of surrounding structures. Most abdominal wall expanders are used to expand abdominal skin and are placed under­neath the skin and subcutaneous tissue, but above the fascia.
Preoperative considerations should include a physical exam assessing the patient’s general medical condition, abdominal wall integrity, extent and location of abdominal wall abnormali­ties, and the presence of scars. Using these prin­ciples, Livingston et al. described their technique for providing soft-tissue coverage for traumatic abdominal wall defects. The open abdomen wounds are fi rst temporized with a split thickness skin graft which forms a skin bridge. Once the skin graft demonstrates substantial mobility from the underlying viscera, the patients are deemed to be candidates for tissue expander placement, usually at a minimum of 6 months [ 8 ]. The tissue expanders are inserted in the subcutaneous plane above anterior rectus fascia with retention of split thickness skin graft. Expansion is then carried out weekly or biweekly over approximately 6 weeks. After adequate expansion, the tissue expander is removed and the split thickness skin graft is de-epithelialized to form a “connective tissue bridge” (deep layer) over which the expanded subcutaneous tissue and skin is closed [ 8 ]. The expanded tissue may need to undergo capsulotomies or capsulectomies of the expander pocket for greater tissue movement [ 10 ]. It is important to note that this does not address the hernia itself, but only provides adequate skin and subcutaneous tissue coverage for the defect and/ or prosthetic. Potential disadvantages to abdomi­nal wall reconstruction with mesh and tissue expansion includes a possibility of skin break­down and resultant mesh exposure and infection [ 10 ]. However, increased vascularity in the expanded tissue may decrease the potential skin fl ap ischemia, necrosis, and subsequent wound break down and mesh infection [ 10 ].
Another drawback of TE is that the typical expansion technique involves staged operations over a period of several weeks or months and multiple postoperative visits. Tissue expanders have the potential to become infected or exposed during expansion. In fact, complications related to using tissue expanders have been reported to be about 15% [ 10 ]. Rates of complication vary in relation to the site of implantation. Expansion over bony prominences, burn scars, or previous incision sites tends to have the highest morbidity [ 10 ].
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L. Chmielewski et al.
Unlike internal expanders, external expanders stretch the skin and subcutaneous tissue by pro­viding constant dermatraction at the wound edges. This can be achieved by placing an elastic vessel loop at the wound edges and adjusting the tension of the vessel loop postoperatively. Commercially available external tissue expand­ers, such as the Dermaclose™ (Wound Care Technologies Inc. Chanhassen, MN), provide constant and continuous tension at the wound edges. The wound edges should be adequately undermined prior to the application of the exter­nal dermatraction device to allow for appropriate movement of the skin fl aps.
Conclusion
Tissue expansion can be a valuable tool in the reconstructive armamentarium. Its applications in abdominal wall reconstruction have been thor­oughly reviewed in this chapter. Appropriate indi­cations for expansion of the abdominal wall are when there is a defi ciency in abdominal skin and subcutaneous tissue and a clean wound. Advantages of tissue expansion include the ability to create and recruit tissue having similar aesthetics of color, texture, thickness, and hair production. However, these advantages must be balanced with the downside that expansion requires staged operations over a period of several weeks or months and multiple postoperative visits. Additionally, expansion can be associated with the risks of infection, fl ap ischemia, extru­sion, implant failure, patient intolerance, pain,
and scar widening. Each of these complications may necessitate prosthesis removal. For these reasons, judicious use of tissue expanders is recommended as just one of many tools for abdominal wall reconstruction.
References
1. Althubaiti G, Butler CE. Abdominal wall and chest wall reconstruction. Plast Reconstr Surg. 2014;133: 688e–701.
2. Ramirez OM, Ruas E, Dellon AL. “Components sep­aration” method for closure of abdominal-wall defects: an anatomic and clinical study. Plast Reconstr Surg. 1990;86:519–26.
3. Byrd HS, Hobar PC. Abdominal wall expansion in congenital defects. Plast Reconstr Surg. 1989;84: 347–52.
4. Weinzweig J, Weinzweig N. Plastic surgery tech­niques (Chapter 5). In: Guyuron B, editor. Plastic sur­gery indications and practice. Saunders/Elsevier: Edinburgh; 2009. p. 90–108.
5. Leedy JE, Janis JE, Rohrich RJ. Reconstruction of acquired scalp defects: an algorithmic approach. Plast Reconstr Surg. 2005;116:54e–72.
6. Arneja JS, Gosain AK. Giant congenital melanocytic nevi. Plast Reconstr Surg. 2007;120:26e–40.
7. Marks MW, Argenta LC. Principles and applications of tissue expansion (Chapter 27). In: Neligan PC, edi­tor. Plastic surgery. London: Saunders/Elsevier; 2012. p. 621–31.
8. Livingston DH, Sharma PK, Glantz AI. Tissue expanders for abdominal wall reconstruction follow­ing severe trauma: technical note and case reports. J Trauma. 1992;32:82–6.
9. Tran NV, Petty PM, Bite U, et al. Tissue expansion assisted closure of massive ventral hernias. J Am Coll Surg. 2003;196:484–8.
10. Paletta CE, Huang DB, Dehghan K, Kelly C. The use of tissue expanders in staged abdominal wall recon­struction. Ann Plast Surg. 1999;42:259–65.
Flap Reconstruction of the Abdominal Wall
Donald P. Baumann and Charles E. Butler
Introduction
Soft-tissue fl ap reconstruction of the abdominal wall implies the inability to recruit local tissue to resurface the abdominal wall defect. Since the majority of abdominal wall defects can be recon­structed with the surrounding redundant tissue from the torso, these defects represent a more complex subset of abdominal wall reconstruc­tions. Indications for fl ap coverage vary by etiol­ogy, defect characteristics, and timeline for closure. Multiple clinical scenarios can lead to a loss of abdominal wall soft-tissue requiring fl ap recon­struction, including massive ventral hernia with loss of domain , traumatic injury, soft tissue infec­tion, oncologic resection, and the open abdomen.
The surface area of soft-tissue loss and the amount of wound coverage able to be performed with local skin advancement must be factored into the reconstructive plan. Abdominal wall defects requiring soft-tissue fl ap coverage can be classifi ed as partial thickness defects involving the skin and subcutaneous tissue only or full­thickness composite defects which involve loss of the abdominal wall musculofascia in addition to the overlying skin and subcutaneous tissue.
D. P. Baumann , M.D., F.A.C.S. C. E. Butler , M.D., F.A.C.S. ( Plastic and Reconstructive Surgery , University of Texas MD Anderson Cancer Center , Houston , TX , USA
cbutler@mdanderson.org
e-mail:
*)
30
The indications for soft-tissue fl ap coverage in abdominal wall reconstruction also depend on the chronicity of the wound defect with some defects benefi ting from early fl ap coverage, oth­ers best treated by delayed fl ap coverage. Certain other defects are more appropriately managed with chronic wound care and healing by second­ary intention.
Historically, abdominal wounds were treated with wound care and allowed to heal over time by secondary intention or were reconstructed with a skin graft after the local wound environment was optimized. This resulted in a prolonged course of care and signifi cant morbidity. In time, the con­cept of delayed-primary closure gained popularity allowing certain patients with favorable wound characteristics to undergo closure after a short period of wound care instead of being committed to weeks or months of open wound care. This enabled patients to achieve defi nitive wound clo­sure without a skin-grafted surgical site and asso­ciated donor site morbidity [ 1 ].
Early soft-tissue fl ap reconstruction offers sig­nifi cant advantages over delayed-primary or secondary healing wound closure. Flap recon­struction is performed as a single stage procedure obviating the need for chronic wound manage­ment. Flap reconstruction can often be performed at the same time as the musculofascial recon­struction. Flap reconstruction offers immediate and defi nitive wound closure, effectively ending the local tissue injury and infl ammatory response seen in chronic open wounds. These two factors
Y.W. Novitsky (ed.), Hernia Surgery, DOI 10.1007/978-3-319-27470-6_30
313© Springer International Publishing Switzerland 2016
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are critical in reconstructions involving abdomi­nal wall reinforcement with bioprosthetic mesh. When bioprosthetic mesh is interposed between two well-vascularized tissue planes (posterior abdominal wall/peritoneal cavity and a soft tissue fl ap superfi cially), bidirectional vascular ingrowth can be achieved accelerating the period of bioprosthetic mesh revascularization and incorporation. In addition, a closed wound envi­ronment diminishes the pro-infl ammatory state of an open wound, which limits the degree of enzymatic degradation of the bioprosthetic mesh during the incorporation phase [ 2 ].
Over the last 20 years, the role of negative­pressure wound therapy (NPWT) has revolution­ized the approach to wound care, particularly in the management of abdominal wall defects. NPWT allows preservation of the wound envi­ronment by managing fl uid and protein losses, decreasing bacterial contamination and acceler­ating granulation tissue formation. In abdominal wall reconstruction, this translates in preserving the option for delayed-primary closure or delayed fl ap reconstruction [ 3 ].
Composite, full-thickness loss of the abdominal wall musculofascia and overlying soft-tissue represent the most complicated abdom­inal wall reconstructions, sometimes requir­ing multiple staged reconstructive procedures. Re-establishment of musculofascial continuity is paramount to setting the stage for a durable abdominal wall reconstruction. Reconstituting the defi cient musculofascia with a mesh inlay converts the open abdomen to a more manageable abdominal wall wound. For midline defects, early abdominal closure with primary rectus musculo­fascial re-approximation over bioprosthetic mesh provides superior outcomes to bridging the fascial defect with bioprosthetic mesh. The risk of devel­oping a hernia increases sevenfold when bridging fascial repairs are performed instead of reinforced mesh repairs [ 4 ]. All attempts should be made to achieve fascial coaptation as bridging repairs are far more likely to develop hernias. When early fascial closure is not an option owing to ongoing debridement of the musculofascia or the need to perform a second- look laparotomy, a temporizing abdominal wall closure can be utilized such as the
NPWT system. A static bridging wound dress­ing protects and insulates the viscera while con­trolling fl uid loss in the wound bed. NPWT also provides abdominal stability in the early postop­erative period for patients undergoing mechani­cal ventilation and later when they ambulate and undergo physical therapy.
When both the soft-tissue and musculofascia require reconstruction, it is preferred to recon­struct these two components independently, rather than using the fascia of the fl ap for musculofascial reconstruction. Historically, before the introduc­tion of mesh material for use in contaminated cases, fl aps such as the tensor fascia lata fl ap were used to reconstruct full-thickness abdominal wall defects, especially in the setting of wound con­tamination [ 5 ]. Selecting a single fl ap to restore the musculofascial integrity and resurface the skin defect can compromise durability of the hernia repair as well as lead to a perfusion-related com­plication (wound dehiscence, fl ap necrosis) at the skin level. The current approach to these defects includes mesh and often component separation release to re-establish a physiologic tension bear­ing musculofascial closure and then a soft-tissue fl ap is used for the cutaneous defect. The use of the fascial component of a fl ap for musculofascial reconstructions can result in increased bulge or hernia. In addition, insertion of the fascial compo­nent can potentially compromise the vascularity of the soft-tissue component of the fl ap. Thus, for composite midline defects, myofascial recon­struction is generally performed with either syn­thetic or bioprosthetic mesh materials. Surgeon preference and the variables of any given clinical scenario will determine whether bioprosthetic mesh or synthetic mesh is used. Regardless of mesh type, the expectations are that the mesh will maintain the abdominal musculofascial structure, integrity, and contour, without development of a hernia or bulge. Mesh should be placed to avoid forming extensive adhesions to the intra-abdomi­nal viscera that can lead to bowel obstruction or fi stulization. Bioprosthetic and synthetic meshes can meet these expectations, and the decision to use either is based on patient comorbidities, degree of wound contamination, prior radiation, availability of greater omentum to interpose
30 Flap Reconstruction of the Abdominal Wall
315
between mesh and bowel, and the quality of the overlying soft-tissue.
The reconstructive algorithm for skin cover­age of full-thickness abdominal wall defects begins with local skin advancement fl aps and expands to local perforator fl aps, regional pedi­cled fl ap , and ultimately free-fl ap reconstruc­tions. The overlapping angiosomes of the abdominal wall’s cutaneous blood supply allow
abdominal wall defects can involve signifi cant loss of innervated myofascia and overlying skin in a dimension that is greater than the surround­ing tissue’s ability to be recruited and mobilized for closure. In such cases, regional or distant tis­sue fl aps must be used for closure, and the resul­tant repair will no longer be dynamic, contractile, and coordinated with the surrounding abdominal
wall musculature. for wide undermining and robust skin advance­ment. In addition, tissue expansion (Chapter 29 ) can be performed in the trunk to increase the sur­face area and availability of local fasciocutane-
Overview of Reconstruction
by Regio n
ous fl aps as an alternative to a pedicled or free-fl ap donor site. In cases of prior radiation, extensive prior scars, or massive skin resection, a pedicled regional or free fl ap may be required to provide adequate soft-tissue coverage. Composite
Table 30.1 Abdominal wall fl ap reconstruction algorithm epigastric defects
Local Pedicled Free
Epigastric Transposition IM, IC, SE Rectus Thigh-based (ALT, AMT, VL, TFL, RF, STF)
Keystone Omentum Back-based LD, TAP, Scap/Para Bipedicled Fasciocutaneous
IM internal mammary artery perforator fl ap, IC intercostal artery perforator fl ap, SE superior epigastric artery perforator fl ap Thigh-based: ALT anterolateral thigh fl ap, AMT anteromedial thigh fl ap, VL Vastus lateralis fl ap, TFL tensor fascia lata fl ap, RF rectus femoris fl ap, STF subtotal thigh fl ap Back-based: LD latissimus dorsi fl ap, TAP thoracodorsal artery perforator fl ap, Scap/Para scapular/parascapular fl ap
The anterior abdominal wall can be divided into
three anatomic regions: the epigastrium, the peri-
umbilical region and the hypogastrium. (Tables
30.1 , 30.2 and 30.3 ) The relationship of defects
Table 30.2 Abdominal wall fl ap reconstruction algorithm periumbilical defects
Local Pedicled Free
Periumbilical Transposition DIEP, SIEP, TLP Rectus Thigh-based ALT, AMT, VL, TFL, RF, STF
Keystone Omentum Back-based LD, TAP, Scap/Para Bipedicled fasciocutaneous Thigh-based
DIEP deep inferior artery perforator fl ap, SIEP superfi cial inferior epigastric artery perforator fl ap, TLP thoracolumbar perforator fl ap Thigh-based: ALT anterolateral thigh fl ap, AMT anteromedial thigh fl ap, VL vastus lateralis fl ap, TFL tensor fascia lata fl ap, RF rectus femoris fl ap, STF subtotal thigh fl ap Back-based: LD latissimus dorsi fl ap, TAP thoracodorsal artery perforator fl ap, Scap/Para scapular/parascapular fl ap
Table 30.3 Abdominal wall fl ap reconstruction a lgorithm hypogastric defects
Local Pedicled Free
Hypogastric
DIEP deep inferior artery perforator fl ap, SIEP superfi cial inferior epigastric artery perforator fl ap, TLP thoracolumbar perforator fl ap Thigh-based: ALT anterolateral thigh fl ap, AMT anteromedial thigh fl ap, VL vastus lateralis fl ap, TFL tensor fascia lata fl ap, RF rectus femoris fl ap, STF subtotal thigh fl ap Back-based: LD latissimus dorsi fl ap, TAP thoracodorsal artery perforator fl ap, Scap/Para scapular/parascapular fl ap
Transposition DIEP, SIEP, TLP Keystone Bipedicled Fasciocutaneous
Rectus Thigh-based ALT, AMT, VL, TFL, RF, STF Omentum Back-based LD, TAP, Scap/Para Thigh- Based
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D.P. Baumann and C.E. Butler
to these anatomic regions guide decision-making when regional p edicled fl aps are planned for reconstruction. Options for pedicled fl aps in the upper abdomen include latissimus dorsi, and omental fl aps. Thigh-based fl aps such as antero­lateral thigh, vastus lateralis, and tensor fascia lata fl aps are generally able to reach the hypogas­trium and fl ank as pedicled fl aps. If a pedicled fl ap is not available or feasible, a thoracoepigas­tric bipedicled fasciocutaneous fl ap may provide a local tissue alternative in patients who are not candidates for free tissue transfer.
When the volume of tissue loss or the arc of rotation needed precludes a pedicled fl ap trans­fer, a free fl ap is required for soft-tissue coverage. The thigh can serve as a source of fasciocutane­ous fl aps and myocutaneous fl aps that provide large skin paddles and signifi cant muscle volume. Recipient vessels in the abdominal wall include the deep inferior epigastric, superior epigastric, internal mammary, intercostal artery, and perfo­rating thoracolumbar. When no local recipient vessels are available, vein grafts to the internal mammary or femoral vessels may be required depending on defect location.
Local Flap Options
Local fl aps involve recruiting tissue adjacent to the wound defect. Well-planned incisions are critical to preserve blood supply to the local fl ap and avoid wound-healing complications at the donor site used to resurface the wound defect. There are various fl ap transposition designs available including advancement, rotation/ advancement, interpolation, V-Y advancement, and bipedicled fl aps. These fl aps can be oriented in any dimension: vertically, obliquely, or hori­zontally. Given these fl aps are perfused through random or axial blood supplies, understanding of the vascular anatomy in terms of abdominal wall angiosomes and perforator location is critical to designing robust local fl aps.
It is also important to consider the impact of preexisting incisions in the abdominal wall when planning a fl ap design. A midline laparotomy may preclude harvesting a local fl ap from the
contralateral abdominal wall. However, a midline defect bisected by a laparotomy scar can be divided in half and reconstructed by two local fl aps, one from each hemi-abdomen. Another key factor in performing a local fl ap reconstruction is limiting tension across the wound closure both at the defect site and the donor site. The fl ap perfu­sion, especially at the most distal part of the fl ap, can be compromised if the fl ap is placed on high tension either by pushing the limits of the fl ap design or by creating excessive bi-axial tension across the fl ap when the donor site is closed.
One strategy that can be employed to mitigate excessive tension across the fl ap is to transpose the fl ap to cover the defect and then skin graft the donor site. This concept is the mainstay of the bipedicled fl ap in trunk reconstruction. For mid­line defects, a bipedicled fasciocutaneous fl ap is generally used for midline defects either unilater­ally or bilaterally. The fl ap is oriented vertically with a maximum of a 3:1 length/width ratio and maintains a blood supply from both the superior and inferior aspects of the fl ap. The fl ap is then directly transposed to resurface the defect and by design the donor site cannot be closed without an undue degree of tension. To offl oad the tension, a skin graft can be used to resurface the donor site preserving blood supply to the distal fl ap to maxi­mize wound healing.
Perforator fl aps are based on a dominant named vessel which perfuses the entire fl ap through an organized vascular network. Perforator fl aps present multiple options for fl ap design and rotation throughout the entire abdom­inal wall. Flaps based on internal mammary, superior epigastric, deep inferior epigastric, superfi cial inferior epigastric, and superfi cial cir­cumfl ex iliac perforators provide local fl ap options in all zones of the abdominal wall. The keystone fl ap is one strategy to reconstruct large trunk defects with perforator fl aps [ 6 ]. Keystone fl aps enable one stage resurfacing of both the defect and donor site. The fl ap is designed as a large 3:1 ellipse parallel to the long axis of the defect. The blood supply to the fl ap is based on cutaneous perforators that shift towards the defect when the fl ap is advanced. Once the lead­ing edge of the keystone fl ap is inset, the donor
30 Flap Reconstruction of the Abdominal Wall
317
site is then closed on itself from the poles of the long axis of the fl ap to the side of the fl ap remote from the defect. The success of this fl ap is due to the transposition tension from the advancement and closure being distributed over the lengthy circumference of the fl ap skin island.
Regional Flap Options
In cases where the defect size exceeds the avail­ability of local soft-tissue for coverage, the next line option is to consider a regional pedicled fl ap . Use of regional fl aps is often limited as the defect is adjacent to the fl ap donor site, particu­larly if the defect is a full-thickness, or compos­ite defect. Regional pedicled fl aps are harvested from adjacent anatomic areas such as the chest, groin, thigh, or back. Pedicled fl aps can be designed as fasciocutaneous fl aps, myocutane­ous fl aps, or muscle fl aps resurfaced with a skin graft. When selecting a pedicled fl ap it is impor­tant to factor the donor morbidity incurred. As an example, a contralateral vertical rectus abdominis myocutaneous fl ap can be used to reconstruct a lower lateral abdominal wall defect; however, the donor site closure may com­promise the fl ap inset, increasing the risk of postoperative complication s. In addition, not only must the pedicled fl aps ability to “reach” the defect be considered, but also how the trans­ferred fl ap will tolerate the rotational, fl exion/ extension forces placed on it in the trunk. As an example, a vastus lateralis thigh fl ap can be used to resurface a hypogastric defect however, as the fl ap’s pedicled vessels remain in their site of ori­gin in the thigh, the fl ap pedicle can pivot and traverse the groin and have its blood fl ow com­promised by compression or rotation during the postoperative period.
Free Flap Options
Microsurgical free tissue transfer enables the reconstructive surgeon to provide soft-tissue cov­erage for abdominal wall defects that are not amenable to either local or regional fl ap cover-
age. Flaps of essentially any size, volume, dimen­sion, and composition can be transferred from donor sites remote from the abdominal wall. While much more technically demanding, the evolution of microsurgical techniques enables successful free-fl ap transfer in excess of 98% of cases [ 7 ].
There is a multitude of free-fl ap donor site options available for abdominal wall reconstruc­tion. The torso and thigh are the main areas of fl ap harvest for defects extending from the upper abdominal wall and epigastrium to the suprapu­bic region. The posterior c hest wall donor site yields the latissimus dorsi myocutaneous fl ap, scapular/parascapular fasciocutaneous fl aps, tho­racodorsal artery perforator fl aps, and serratus anterior muscle fl aps. (Fig. 30.1a–e ) In addition, these fl aps can be harvested together as a chime­ric fl ap to increase the tissue volume for fl ap transfer. These fl aps can also be transposed to the upper epigastrium or lateral subcostal region as a pedicled fl ap. For defects beyond the reach of the thoracodorsal pedicle, the fl ap can be converted to a free fl ap and be transposed anywhere in the abdominal wall.
In cases where a large skin paddle is required for the abdominal wall defect, a free scapular or parascapular fl ap can be designed on the circum­fl ex scapular branch of the subscapular arterial system. If a latissimus or serratus fl ap is har­vested, the functional donor site impact must be considered as it relates to the weakened abdomi­nal wall. Patients who have decreased core mus­cle strength will rely on upper extremity strength and range of motion to complete activities of daily living. The impact of impaired shoulder and upper extremity movement should be considered in these patients. In addition, in terms of logisti­cal planning, the patient must undergo an intra­operative position change to facilitate fl ap dissection in the posterior chest wall . This adds complexity and additional time to the procedure and extends fl ap ischemia time.
The thigh represents the mainstay for fl ap donor sites for the abdominal wall. Both pedicled fl aps for coverage of the infraumbilical abdomi­nal wall and free fl aps can be designed in several of confi gurations: fasciocutaneous, myocutane-
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Fig. 30.1 Free chimeric latissimus myocutaneous fl ap with serratus muscle fl ap reconstruction of epigastric defect. ( a ) Preoperative view of planned composite full- thickness resection of the abdominal wall including ante­rior refl ection of diaphragm. ( b ) Bioprosthetic mesh inlay bridging repair of the thoraco-abdominal defect. ( c ) Free
ous, muscle, and chimeric fl aps. The descending branch of the lateral circumfl ex femoral system provides blood supply to the vastus lateralis, rec­tus femoris muscles, and anterolateral thigh skin. The transverse branch of the lateral circumfl ex femoral system provides blood supply to the ten­sor fascia lata fl ap. These fl aps can be harvested as muscle-only fl aps or as myocutaneous fl aps with overlying skin paddles. The anterolateral thigh fl ap is designed by including a skin paddle overlying vastus lateralis muscle and can be designed as a myocutaneous or fasciocutaneous fl ap. The tensor fascia lata fl ap can be designed to include the distal fascia of the iliotibial tract and a smaller proximal skin paddle, if needed. The
chimeric latissimus myocutaneous fl ap with serratus mus­cle fl ap. ( d ) Serratus muscle fl ap inset covering the bio- prosthetic mesh with the latissimus myocutaneous fl ap providing skin coverage. Right internal mammary vessels used as recipient vessels. ( e ) Follow-up 6 months
anteromedial thigh fl ap can be designed on medial perforators from the descending branch of the lateral circumfl ex femoral system. The rectus femoris muscle is more commonly designed as a muscle fl ap; however, a skin island can be included over the central muscle when appropri­ate-sized cutaneous perforators are present.
These thigh-based fl aps can be designed in any combination as chimeric fl aps, i.e., ALT with AMT fl aps, ALT with TFL, vastus lateralis with TFL. For massive abdominal wall defects, the vastus lateralis, tensor fascia lata, and the rectus femoris can be harvested with all overlying skin territory as a subtotal thigh fl ap for increased volume and skin coverage [
8 ].
30 Flap Reconstruction of the Abdominal Wall
319
Recipient Vessel s
The success of any free tissue transfer relies on the availability of suitable recipient vessels pro­viding arterial infl ow and venous outfl ow to the free fl ap. There are several recipient vessels available for abdominal wall reconstruction with free fl aps. The main vascular axis in the central abdominal wall is the internal mammary-superior epigastric-inferior epigastric system. The internal mammary and deep inferior epigastric vessels provide large caliber 2–3 mm diameter recipient vessels for microanastomosis. However, these vessels are present at the most cephalad and cau­dal limits of the abdominal wall. The main chal­lenge for identifying adequate internal mammary or epigastric recipient vessels in the periumbili­cal region is that they are much smaller in caliber and present more technically challenging micro­anastomoses. In cases where the internal mammary- epigastric vascular axis is unavailable, the thoracodorsal pedicle in the axilla can be reached by using vein grafts.
Recipient vessel options exist beyond the abdominal wall itself. There are a number of options in the groin based on the superfi cial fem­oral system. The superfi cial inferior epigastric artery, the superfi cial circumfl ex iliac artery, and the deep circumfl ex iliac artery provide reason­able caliber vessels for free fl ap transfer to the lower central and lateral abdominal wall. If pri­mary anastomosis is not feasible then vein grafts or vein loops are required. Vein grafts are often harvested from the leg (greater or less saphenous vein) or arm (cephalic vein). In addition, in abdominal wall reconstructions with concurrent laparotomy intra-abdominal vessels can be used as recipients if there are no local options in the abdominal wall. The omental and gastroepiploic vessels can be mobilized to reach the undersur­face of the abdominal wall. Care must be taken in insetting and supporting the fl ap pedicle so that there is no tension on the anastomoses when the visceral contents shift when the patient transi­tions from supine to sitting/standing. In addition, the morbidity of re-entering the abdominal cavity must be considered if there is a vascular throm­bosis requiring fl ap re-exploration. In addition,
when mesh is used for the musculofascial recon­struction as an adjunct to the fascia of the fl ap the pedicle must traverse an aperture in the abdomi­nal wall mesh that increases the risk of pedicle kink and vascular compromise. Moreover, defects in abdominal wall integrity increase the risk of hernia. For these reasons, local recipient options should be explored before intra- abdominal ves­sels are selected.
Vein grafts and arterialized vein loops can be designed to provide adequate recipient vessels in the central abdominal wall. Vein grafts can be harvested from either the upper or lower extrem­ity as a cephalic vein graft or saphenous vein graft. For central and lower abdominal defects an arterialized saphenous vein loop can be designed. (Fig. 30.2a–e ) The saphenous vein is dissected and transected distally and then anastomosed to the superfi cial femoral artery or a side branch. This allows delivery of the loop to the fl aps recip­ient site where the loop is divided providing an arterialized afferent limb and a venous drainage efferent limb. One advantage of this technique is that it only requires three vascular anastomoses instead of four as in the case with direct individual arterial and venous vein grafts. The main recipi­ent vessel sites for vein grafts or arterialized vein loops are the thoracodorsal vessels in the axilla, branches of the superfi cial femoral system on the groin, and the deep inferior epigastric vessels in the lateral abdominal wall, which can be used to extend the reach of vein grafts to the central abdominal wall.
Abdominal Wall Transplantation
Abdominal wall transplantation represents the zenith of abdominal wall fl ap reconstruction. It is generally reserved for patients undergoing single or multi-organ visceral transplants in which abdominal wall closure by autologous fl aps is not technically feasible or presents signifi cant donor morbidity. Abdominal wall closure after visceral organ transplantation is challenging in the setting of donor/recipient organ size mismatch and/or prior recipient abdominal surgery. Transplant patients can benefi t from vascularized composite
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D.P. Baumann and C.E. Butler
Fig. 30.2 Free anterolateral thigh (ALT) fl ap reconstruction of abdominal wall. ( a ) Preoperative view of open abdomen treated with NPWT. ( b , c .) A right-sided ALT fl ap with vas- tus lateralis muscle was harvested on the descending branch
abdominal wall allotransplants as an additional strategy to expand the domain of the abdominal cavity to account for either a graft/recipient size mismatch or inability for closure in the face of extreme intestinal edema. While the risks of life­long immunosuppression potentially outweigh the potential benefi ts of abdominal wall trans­plantation in healthy non-transplant patients, transplant patients are already bound to an immu­nosuppressive regimen and can benefi t from the addition of allograft abdominal wall musculofas-
of the lateral femoral circumfl ex system. ( d ) A shapeno-fem- oral A-V loop was delivered into the lower abdominal defect to serve as recipient vessels. ( e ) Patient at 12 weeks follow- up. Flap reconstruction algorithm by region
cial tissue to reduce abdominal wall wound com­plication at the time of transplantation.
In the setting of transplant immunosuppres­sion, the risk of an open abdominal wound, fascial dehiscence, septic evisceration or fi s­tula carries signifi cant morbidity and potential mortality. When conventional abdominal wall closure techniques are insuffi cient allotransplan­tation is performed. Extensive study of the vas­cular supply of the abdominal wall has allowed design of musculofasciocutaneous fl aps based