Perfusion classification in a IR injury DIEP flap model observed to be statistically unrelated to the number of venous anastomoses in a large retrospective study by Gill et al6. In bilateral DIEP flap breast reconstruction, the use of zone III and zone IV is eliminated by the division of the flap in the midline. Only zone I and zone II are incorporated in bilateral DIEP reconstruction, and still, an incidence of 12.5% FN is reported, which is comparable to unilateral breast reconstruction.11 FN is a multifactorial complication, which is only partially caused by intrinsic vascular anatomy. In contrary to other experimental models, the ischemia period in our study was relatively short. Usually, an ischemia period of 6–8 hours is used in IR injury studies.25‐27 Our study is the first to our knowledge that even a short ischemic period using an experimental model could induce IR‐related PFL. This is also observed in clinical studies where relatively short but incremental ischemic period led to an increase of flap‐related complications in DIEP flaps.28,29 In addition, there is a delayed perfusion of distal parts of the flap, especially after free tissue transfers.19,30,31 Interestingly, in a clinical study using the laser Doppler imager, all the zones of the flap zones maintained normal blood flow when blood supply became restricted to the abdominal vascular pedicle.31 After transplantation of the flap, blood flow was altered, and we observed an increase of the flap centrally compared with measurements before and during surgery. A decrease of peripheral flap blood flow was observed after transplantation. The ischemia period is, as a result, much longer in distal parenchyma compared with parenchyma located centrally over the vascular pedicle31 In conclusion, IR injury may thus be an important etiologic factor in PFL and/or FN in the DIEP flap. The TRAM flap zone classification introduced by Hartrampf et al.32 and later modified by Holm et al.19, dividing the flap in four perfusion zones, should be considered obsolete and not used. Therefore, the DIEP flap can theoretically be divided in three areas: (A) the central zone, (B) a zone that is vulnerable to IR injury, and (C) a zone of distal ischemia (Figure 7.5). Figure 7.5 Therefore, the DIEP flap can theoretically be divided in three areas: (A) the central zone, (B) a zone that is vulnerable to IR injury, and (C) a zone of distal ischemia. This new classification of the flap is more physiological than the previously used classification that divides the flap in zones I–IV. 107
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