Venous Interruption Is Unnecessary to Achieve an Adequate Delay in the Rat TRAM Flap Model:

Microcirculation in DIEP flaps: a study of the haemodynamics using laser Doppler flowmetry and lightguide reflectance spectrophotometry

The deep inferior epigastric perforator (DIEP) flap is ideally suited for breast reconstruction. The DIEP flap reduces abdominal wall morbidity when compared to a transverse rectus abdominis (TRAM) flap, however, there maybe a compromise of the flap vascularity. Early venous problems and late fat necrosis in DIEP flaps can occur. There is a limited literature on the haemodynamic and microcirculation of the DIEP flap. Sixteen consecutive patients who underwent immediate breast reconstruction with DIEP flap were prospectively monitored during the post-operative time for a minimum period of 48h using laser Doppler flowmetry (LDF) and lightguide reflectance spectrophotometry (LRS) to analyse blood flow and oxygenated haemoglobin percentage in the cutaneous microcirculation of the flap. LDF demonstrated an increase of capillary flow in comparison to the pre-operative levels. LRS showed an initial decrease of the values and a varying pattern of increase in relation to time, to reach the pre-operative levels. A correlation between lower values of post-operative LDF and LRS measurements and late fat necrosis and early venous congestion was demonstrable in this series. This study demonstrates a change in the cutaneous microcirculation of the lower anterior abdominal wall following its elevation as a DIEP flap. These findings could explain the clinical phenomenon occurring in this flap in the early post-operative period. Significant correlation between longer harvesting time and re-exploration and between longer ischaemia time and localised fat necrosis was found.

Venous “Supercharging” Augments Survival of the Delayed Rat TRAM Flap

Adequate delay of a pedicled transverse rectus abdominis musculocutaneous (TRAM) flap might not necessarily require interruption of the venous system. The retained ipsilateral deep vein of the dominant pedicle could then be used as a secondary outflow source for potential salvage of a congested flap. A venous "supercharged" rat TRAM flap model has been designed to evaluate the efficacy of this maneuver. Seventy-two female Sprague-Dawley rats (CD) were equally divided into two major groups, differing only in whether a delay by division of the dominant cranial epigastric artery had first been performed. An inferior-based TRAM flap (nondominant) was raised for each rat, with three subsets of 12 rats in each group, ie, with the cranial epigastric vein subsequently divided (group control), retained (supercharged), or retained but the inferior pedicle divided (venous flap). Both supercharged subsets had significantly augmented flap survival when compared with flaps in their group raised without the cranial epigastric vein, whether a delay maneuver had (96 +/- 6% vs 89 +/- 7%; P = 0.012) or not (80 +/- 8% vs 65 +/- 21%; P = 0.034) been performed. Flaps with only a cranial epigastric vein pedicle totally necrosed, implying that the observed enhancement in flap viability was not the result of transformation into a venous flap, but perhaps as a crossover flap where an adjacent venosome was captured. Venous supercharging can be accomplished by inclusion of the ipsilateral dominant deep vein, and should be a consideration in the clinical planning of delay maneuvers and for treatment of the compromised TRAM flap.