Pedicle-to-Perforator Bypass Using Supermicrosurgical Technique for Deep Inferior Epigastric Artery Perforator Flap Salvage.

Sir:

Appropriate perforator selection is critical to successful deep inferior epigastric artery perforator flap harvest. Although the optimal number of perforators to be included is often debated, commitment to a single, dominant perforator simplifies dissection, reduces operative time, and minimizes donor-site morbidity when compared with multi-perforator flap designs.[1] A potential drawback of this approach, however, relates to inadvertent perforator injury, which has a reported incidence as high as 4.3% and bears devastating prognostic implications.[2] When discovered in-situ, conversion to a muscle-sparing alternative may facilitate flap salvage. However, the majority (71%) of these injuries are attributed to perforator mishandling (i.e., traction-induced) during flap transfer/inset, rather than technical error of dissection, itself.[2] As such, perforator-level injuries often go unnoticed until arterial insufficiency and/or venous congestion become evident following microvascular anastomosis.

When this scenario is encountered intraoperatively, emergent microsurgical intervention offers the only reliable solution to avoid catastrophic flap loss. To this end, strategies that incorporate the superficial inferior epigastric artery/vein, with or without vein grafting and/or pedicle turbocharging, have been proposed to redirect flap inflow/outflow, respectively.[3,4] These techniques, however, require preemptive planning and preservation of viable superficial inferior epigastric artery/vein, which are present in fewer than 30% of cases.[5] In situations where the superficial system is inadequate/unavailable, segmental resection and anastomosis of the injured perforator to itself may aid in the reestablishment of nutritive perfusion.[2] Although high success rates (83%) have been reported with this approach, perforator-to-perforator anastomosis in the setting of prior trauma can be technically challenging and increases the likelihood of thrombotic complications.[2]

A safer alternative to restore microcirculation involves interperforator bypass between previously ligated, nontraumatized perforators within the flap and preserved pedicle side branches (Fig. 1). After ligation/division of the injured perforator, the undersurface of the flap and pedicle are each investigated to identify suitable perforator remnants. Donor/recipient perforators are preferentially selected on the basis of vessel caliber (0.3–0.5 mm diameter), length (4–6 mm), and absence of prior trauma (i.e., cauterization). Perforator dissection/anastomosis are performed under microscopic guidance utilizing meticulous supermicrosurgical technique with interrupted 10-0 nylon sutures (Fig. 2). After anastomotic patency is confirmed, the pedicle is sutured to the flap to avoid traction and/or accidental avulsion during inset.

Fig. 1.

Diagram illustrating interperforator bypass between previously ligated, non-traumatized perforators/venae comitans within the flap and preserved arterial/venous side-branches originating from the deep inferior epigastric pedicle. The previously injured perforator is seen ligated and divided (ghosted).

Fig. 2.

Intraoperative photograph demonstrating pedicle-to-perforator bypass following delayed discovery of perforator injury in a single, dominant deep inferior epigastric artery perforator free flap. Intraflap dissection provided an additional 4 mm cuff of donor perforator and adjacent venae comitans to facilitate end-to-end anastomosis to arterial and venous side branches off of the main vascular pedicle. Microanastomosis was accomplished utilizing supermicrosurgical instruments and 10-0 nylon interrupted suture. Relative size concordance between the donor perforator and recipient arterial side branch in this case obviated the need for donor vessel spatulation or back-cutting. The pedicle was subsequently secured to the undersurface of the flap with 6-0 absorbable, multifilament suture to prevent perforator avulsion during flap repositioning and inset. DA, donor artery; DV, donor vein; RA, recipient artery; RV, recipient vein.

The advent of supermicrosurgical technique has expanded the indications and options available for salvage of perforator-level injuries. Successful pedicle-to-perforator bypass, as described herein, is dependent on the exclusion of injured vascular segments that pose unjustified thrombogenic risk. Preservation of perforator length during primary flap/pedicle dissection and use of hemoclip ligation optimize the quality/quantity of perforators available for anastomosis.[3,4] In many cases, intraflap dissection and donor spatulation are required to lengthen the vascular cuff and improve size concordance between donor perforators and recipient pedicle side branches.[5] It is our preference to incorporate perforators with accompanying venae comitans (VC), which simplifies the orientation of the arterial/venous pedicles supplying the flap. In the absence of reliable VC, the recipient venous pedicle can be separated along its length from the artery and transferred independently to an adjacent donor VC or the superficial inferior epigastric vein to facilitate flap outflow. Although described in the context of single-perforator deep inferior epigastric artery perforator flaps, pedicle-to-perforator bypass—utilizing a perforator-preserving technique—should be considered a practical salvage maneuver in all cases where delayed perforator-level injury is either suspected or confirmed after microvascular anastomosis.