The Island Perforator Flap Design Augments Vascularity

Abstract

Sir: We read with great interest the article entitled “The Importance of a Skin Bridge in Peripheral Tissue Perfusion in Perforator Flaps,” and we congratulate the authors on their study.1 With dynamic laser-induced fluorescence videoangiography, Mešić et al.1 assessed perfusion of island and nonisland perforator flaps and concluded that conversion of a perforator flap with a skin bridge into an island perforator flap increases peripheral tissue perfusion. Cutting of the skin bridge and conversion of a nonisland flap into an island flap completely divide the dermal/subdermal plexus and are intuitively expected to further impair circulation of the flap. Based on a similar line of thought, perfusion in island flaps is intuitively expected to be lower than that of surrounding skin (or preoperative donor area) due to raising of the flap, division of smaller vessels, and skeletonization of perforators. However, there is now an emerging body of research to suggest otherwise. Rubino et al.2 performed echo color Doppler measurements of diameter and blood flow velocity in deep inferior epigastric, superior gluteal artery, and anterolateral thigh perforator flaps. Their data showed that in the donor area preoperatively, blood velocity in the perforator is lower than that in the corresponding pedicle, whereas after surgery, blood velocity in the perforator is higher than that in the corresponding pedicle. Figus et al.3 assessed hemodynamic changes in deep inferior epigastric perforator flaps with laser Doppler flowmetry. Their study demonstrated an increase of the blood velocity in the circulation of deep inferior epigastric perforator flaps both in the immediate postoperative period and after 3 months. Both groups suggested that the higher velocity within perforator flaps may be a favorable rheologic feature.2,3 We had a case of a 46-year-old man who underwent perineal defect reconstruction with an inferior gluteal artery perforator island flap following laparoscopic abdominoperineal resection of a low rectal malignancy. Seven days after the operation, laser Doppler flowmetry (Moor Laser Doppler Imager; Moor Instruments Ltd., Devon, United Kingdom) assessment of flap perfusion revealed an area of significant hyperperfusion where the inferior gluteal artery entered the flap (Figs. 1 and 2). In comparison to surrounding skin (yellow/green/pink), the perfusion where the pedicle entered the flap was significantly increased (red), while flap perfusion in the areas away from the pedicle was relatively decreased (blue/purple).Fig. 1: The inferior gluteal artery island perforator flap was used to reconstruct the perineal defectFig. 2: Laser Doppler flowmetry displayed in 16-color palette over the range 0 to 230 PU with five marked regions of interest. Flux is highest where the vascular pedicle enters the flap at region 3 (blue, lowest blood flow; red, highest blood flow).In 1975, Behan and Wilson4 introduced the angiotome concept, which culminated in the keystone design perforator island flap. For at least two decades, Behan5 has hypothesized that the island flap design augments vascular perfusion, based on his intraoperative and early postoperative, clinically observed “red dot sign” and hyperaemic flare. In the current era of evidence-based medicine, his observations and interpretations were met with some skepticism until recent years. There are now published clinical series of keystone island flaps reflecting favorable clinical outcomes over decades. It is now gratifying to see the emergence of experimental and basic sciences research that helps to explain our positive experiences with the keystone island flap. Many questions remain unanswered (i.e., in our case, why the perfusion was relatively decreased in the flap areas away from the pedicle), and we look forward to contributing to this body of work on perforator flaps in the near future. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. Cheng Hean Lo, F.R.A.C.S.(Plast.) Hana Menezes, C.C.R.N. Felix Behan, F.R.A.C.S.(Plast.) Monash Health Dandenong, Victoria, Australia