ABSTRACT
As techniques of microsurgery continued to develop and become more widespread, surgeons were able to counter problems of donor morbidity and improve flap viability with use of the “free TRAM flap.” This method of autologous reconstruction completely separates abdominal wall tissue from the lower abdomen, which is then transferred to the anterior chest wall. Microvascular techniques with anastomosis of the deep inferior epigastric vessels to the internal mammary or thoracodorsal vessels are used to restore blood supply to the TRAM flap. The free TRAM flap is based on the deep inferior epigastric vessels rather than the superior epigastric vessels on which the pedicled TRAM flap is based. Anatomic and functional studies have clearly demonstrated that the deep inferior epigastric system provides the dominant arterial and venous supply to the lower abdomen. Studies have also demonstrated that the superior epigastric system can only perfuse the lower abdomen via collateral supraumbilical “choke” vessels, and that the caliber, pressure and flow of blood through the superior epigastric arteries are less that that of the deep inferior epigastric arteries. Thus, the area of the lower abdomen perfused by each superior epigastric system is smaller than the area supplied by each deep inferior system (6-8). This partially
accounts for the higher frequency of venous congestion and partial flap loss witnessed in the pedicled TRAM group when compared with the free TRAM group of patients (9-11). A further benefit of the free TRAM flap is that the integrity of the inframammary fold can be better preserved; thus with a pedicled TRAM flap it is necessary to tunnel through to the chest wall from the upper abdomen to create a passage for the flap. The body of the rectus muscle lies within this tunnel and may allow the inframammary crease to drift inferiorly. Moreover, the rectus muscle can produce an unsightly prominence in the epigastrium, especially with a contralateral pedicled TRAM flap.
