Intraoperative evaluation of blood flow in the internal mammary or thoracodorsal artery as a recipient vessel for a free TRAM flap.

Although the free microvascular transverse rectus abdominis musculocutaneous (TRAM) flap is in routine use for breast reconstruction, little is known of its hemodynamics. The purpose of this study was to determine whether any differences exist when the free TRAM flap is anastomosed to the thoracodorsal or internal mammary vessels. The study comprised 25 patients receiving a free TRAM flap for breast reconstruction. The thoracodorsal vessels were used as recipients in 21 patients and the internal mammary vessels were used in 4 patients. Blood flow rate was measured directly in the donor and recipient arteries, and after anastomosis by a transit-time ultrasonic flowmeter (CardioMed). Two- and 3-mm probes were used. The blood flow rate in the donor artery (deep inferior epigastric) before flap dissection was 11 +/- 6 ml per minute (mean +/- standard deviation). The rate was significantly (p < 0.05) lower (5 +/- 3 ml per minute) in the recipient thoracodorsal artery than in the donor, but after transplantation it increased to 14 +/- 5 ml per minute (p < 0.05), attaining the same value as the donor artery. The blood flow rate in the intact internal mammary artery was significantly higher (25 +/- 10 ml per minute) than in the donor and thoracodorsal arteries, but after anastomosis it dropped to the same value (12 +/- 3 ml per minute; p < 0.05) as the donor artery. The intake of blood in TRAM flaps supplied by the intemal mammary artery seems to be no greater than that in free flaps anastomosed to thoracodorsal vessels, although the flow in the internal mammary artery was much higher. The authors concluded that the blood supply in a free TRAM flap is independent of the flow in the recipient artery and that thoracodorsal vessels, although often in a scarred bed and radiated, are as suitable for anastomosing a free TRAM flap as are internal mammary vessels.