The Perforasome Theory: Vascular Anatomy and Clinical Implications

Sir: We read with much interest the article by Saint-Cyr et al., “The Perforasome Theory: Vascular Anatomy and Clinical Implications,”1 which very clearly highlights some key anatomical factors essential to the design of perforator flaps. Although we congratulate the authors on their superb study and its presentation, as is often the case in research, we have concurrently been performing similar anatomical studies,2 some of which we feel complement this work and can add to an understanding of the perforator angiosome concept. Saint-Cyr et al. demonstrate the arterial anatomy of individual perforators in a series of cadaveric specimens, and although this type of cadaveric research is highly significant, functional changes occur postmortem that may create differences between cadaveric and living vascular anatomy. In a study in which we looked at 200 hemiabdominal walls from both cadavers and patients, we found that the absence of living flow dynamics (loss of sympathetic vascular tone and loss of adjacent tributary flow with buffering from adjacent vessels) combined with the forced pressure during cadaveric angiographic injection caused vessel calibers to be significantly greater in the cadaveric setting.3 As such, it is worthwhile to contribute a similar study to the discussion of the angiosome of individual perforators that we have performed in vivo. Using an imaging modality comparable to that used by Saint-Cyr et al., we performed timed (arterial phase) computed tomographic angiography for preoperative imaging of the abdominal wall vasculature in 145 patients.2 Thus, we analyzed the vascular architecture of 1200 deep inferior epigastric artery perforators. Our in vivo analysis demonstrated findings similar to the cadaveric findings reported by Saint-Cyr et al. and confirm that the findings are applicable in the living state. We found that perforator filling follows a territorial pattern, with perfusion within the subcutaneous tissues occurring in a multidirectional manner and with linking to adjacent perforator territories occurring by means of a combination of direct and indirect (“choke”) communications. We also found that perforator territories varied substantially, even between perforators of the same source vessel, warranting an individualized approach to flap design. An additional feature of perforator territories that we have found but that was not discussed in the article by Saint-Cyr et al. is that of interplay between adjacent perforator territories. We have found that, when there is a dominant perforator or group of perforators, there is a concurrent diminution of adjacent perforators.4 We performed this comparison in 300 patients (600 body sides, and over 2000 perforators), and found that this concept of “perforator dominance” was statistically significant, and that consideration of adjacent perforator territories is important in considering the effect of any single “perforator angiosome.” Regardless of the terminology in use (perforator angiosome or perforasome), it is clear that although individual perforators demonstrate features of the angiosome concept described by Taylor and Palmer,5 there are some unique features of perforators themselves that are essential in the design of perforator flaps. Warren M. Rozen, M.B.B.S., B.Med.Sc., P.G.Dip.Surg.Anat. Mark W. Ashton, M.B.B.S., M.D.