Laser Angiography as a Predictor of Mastectomy Skin Flap Necrosis After Breast Reconstruction

Background

Skin sparing mastectomy improves the aesthetic result of the reconstructed breast while broadening the reconstructive options.  However, intraoperative ischemia leading to postoperative necrosis and mastectomy flap loss can prove difficult to clinically assess during the reconstruction.  Accurate determination of skin flap viability during immediate breast reconstruction is critical to avoid postoperative skin flap necrosis. We review our experience with laser angiography as a predictor of mastectomy skin flap necrosis.

Methods

All skin sparing mastectomy flaps in patients undergoing immediate breast reconstruction over a 2 year period were studied.  The vascularity of each mastectomy flap was assessed clinically and simultaneous images were obtained using intraoperative infrared fluorescent tissue angiography (Novadaq SPY SP2001, Mississauga, Ontario, Canada) with ICG (Akorn, Buffalo Grove, IL).  Postoperatively, the amount of fluorescence (referred to as fluorescence level (FL)) throughout each image was calculated (SPY-Q software, Novadaq, Mississauga, Ontario, Canada), with relative percentages of fluorescent brightness noted when compared to the most well perfused area of each respective flap (or brightest, regarded as 100%).  For each mastectomy flap, the fluorescent images and respective postoperative photographs were then compared and areas of ischemic necrosis were noted.

Results

227 mastectomy flaps in 174 patients were studied.  Poorly perfused mastectomy flap skin, as determined clinically, was resected.  However, postoperative mastectomy skin flap necrosis occurred in 10 breasts (4.41%).  Four of the 10 (40%) developed full thickness necrosis requiring debridement while the remaining six breasts (60%) developed partial thickness necrosis and healed with conservative care.  However, all areas of necrosis displayed a FL of 18% or less (positive predictive value 100%).  Three of the four breasts developing full thickness necrosis (75%, or 30% of all patients developing necrosis) were of patients smoking within six weeks of the mastectomy, and one breast had been previously radiated (100%).  Patients developing partial thickness necrosis did not smoke, nor had a history of pre-mastectomy radiation.  All reconstructions were salvaged using the original procedure.

Conclusions

A FL greater than 18% always predicted uneventful mastectomy skin flap survival.  However, a FL less than 18% predicted partial or full thickness skin flap necrosis.  The depth of necrosis in these flaps correlated to known risk factors of history of smoking and previous radiation.