We thank the authors for their interest in and comments on our recent publication, “Optimizing Perforator Selection: A Multivariable Analysis of Predictors for Fat Necrosis and Abdominal Morbidity in DIEP Flap Breast Reconstruction.”1 We agree that our conclusions could serve as a valuable reference for patient evaluation and surgical decision-making.
This study was indeed retrospective and thus always subject to the operative preferences and decisions of a given surgeon. This is the reason we kept such strict inclusion criteria and analyzed only patients operated on by our same two-surgeon team. We have adopted identical preoperative, intraoperative, and postoperative algorithms. Therefore, the decision-making bias inherently present in all retrospective surgical cohorts was at least kept constant throughout the 6-year period of analysis. The main variables changing from patient to patient were those included in the multivariable model as described.1 We conclude that the subtleties of different indications for different perforator configurations seen on preoperative computed tomographic angiography or in the operating room are therefore less relevant. Rather, in the setting of having the same two surgeons using the same algorithms for a given perforator configuration for the same patient population over the entire study duration, we found that larger, lateral row perforators were associated with decreased odds of postoperative fat necrosis.1
In response to their comments regarding our total flow rate calculation, we conceded in our article1 that “we acknowledge the potential inaccuracies of estimating flow based on external diameters of blood vessels.”2 We would argue, however, that depending on the phase and timing of contrast during computed tomographic angiography, there is not always concordance of preoperative perforator size estimates and those seen intraoperatively. Thus, this is not a perfect solution for estimating total flow rates. Moreover, visual estimates of external diameters of perforators coupled with the pulse and Doppler signal best simulate what is actually used in our operating room to assess perforator quality. These results are therefore more meaningful in our practice where we do not commonly use color duplex ultrasonography or magnetic resonance angiography.
In addition, we agree with the authors that hypertension and smoking can cause internal diameter narrowing of the microvasculature. However, both of these variables were included and controlled for in our statistical analysis.1 If increased blood pressures and smoking had indeed confounded the statistical relationship we found between total flow rate and fat necrosis, this would have been elucidated in our multivariable model.
The importance of venous flow and venous anatomy cannot be overstated, but as the authors mentioned, venous diameter estimations can be even more problematic. This is why we instead carefully analyzed the venous coupler sizes for every flap in our multivariable model.1 This did not have a significant effect on fat necrosis rates or abdominal morbidities.
With regard to their comments on our result showing that using indocyanine green angiography decreased the odds of fat necrosis, we feel that inclusion rather than exclusion of this variable in our analysis is of paramount importance. Only when we identify every possible factor in influencing free flap fat necrosis and include them all in a single multivariable model to account for their potential confounding interactions do we reach reliable and meaningful results. For example, in our preliminary univariable statistics, multiple-perforator flaps had decreased odds of fat necrosis versus single-perforator flaps.1 However, this significance was lost when other variables were accounted for in the multivariable model. Therefore, separating indocyanine green angiography from the other variables we analyzed because it was a significant predictor of decreased odds of fat necrosis would serve opposite to our intended aim.
Our criteria for fat necrosis are established from previously accepted literature.3–5 Although we agree that early fat necrosis can manifest as continual discharge of liquefying adipose tissue, this can often be subtle and hard to distinguish from other clinical manifestations such as serous drainage from resolving edema and subacute or early cellulitis. This is why we postponed the diagnosis of fat necrosis until after 6 weeks.1 This not only accounts for the resolution of normal postoperative edema and healing processes, but also ensures that what we are measuring is clinically relevant fat necrosis. Including subtle wound drainage in the early postoperative period has the potential to invite erroneous variability in our inclusion criteria.
The authors have no commercial or financial associations related to the submitted communication, and no commercial or financial conflicts of interest. No funding was received for the performance of this research of production of the communication.
Nicholas T. Haddock, M.D.
Austin Hembd, M.D.
Sumeet S. Teotia, M.D.
Department of Plastic Surgery
University of Texas Southwestern Medical Center
1. Hembd A, Teotia SS, Zhu H, Haddock NT. Optimizing perforator selection: A multivariable analysis of predictors for fat necrosis and abdominal morbidity in DIEP flap breast reconstruction. Plast Reconstr Surg. 2018;142:583–592.
2. Rozen WM, Whitaker IS, Chubb D, Ashton MW. Perforator number predicts fat necrosis in a prospective analysis of breast reconstruction with free TRAM, DIEP, and SIEA flaps. Plast Reconstr Surg. 2010;126:2286–2288; author reply 2288–2289.
3. Baumann DP, Lin HY, Chevray PM. Perforator number predicts fat necrosis in a prospective analysis of breast reconstruction with free TRAM, DIEP, and SIEA flaps. Plast Reconstr Surg. 2010;125:1335–1341.
4. Grover R, Nelson JA, Fischer JP, Kovach SJ, Serletti JM, Wu LC. The impact of perforator number on deep inferior epigastric perforator flap breast reconstruction. Arch Plast Surg. 2014;41:63–70.
5. Kamali P, Lee M, Becherer BE, et al. Medial row perforators are associated with higher rates of fat necrosis in bilateral DIEP flap breast reconstruction. Plast Reconstr Surg. 2017;140:19–24.
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