THE LONG-TERM EFFECTS OF INTERNAL MAMMARY CHAIN IRRADIATION AND ITS ROLE IN THE VASCULAR SUPPLY OF THE PEDICLED TRANSVERSE RECTUS-ABDOMINISMUSCULOCUTANEOUS FLAP BREAST RECONSTRUCTION

With an increase in breast-sparing surgery and adjuvant radiotherapy, there has been a concomitant increase in the complexity of breast reco nstruction, The effects of radiotherapy on the internal mammary artery were evaluated with respect to flap viability for conventional transv erse rectus abdominis musculocutaneous breast reconstruction using the irradiated rectus muscle, Twenty-eight women who received postoperati ve irradiation for breast cancer were studied, All women had unilatera l irradiation, and evaluation of the internal mammary arteries was per formed at least 1 year after the completion of radiotherapy to allow f or fibrosis and long-term vascular changes, Examination of the interna l mammary artery (upper and lower chains) was performed using color Do ppler sonography to assess vessel diameter, peak systolic velocity, an d blood flow. The nonirradiated side was compared to the radiated inte rnal mammary artery as an internal control. Based on the details of pr ior radiotherapy, the 28 women were designated into two groups, Group I included 14 women with radiation portals that specifically treated t he internal mammary chain; the average dose to the internal mammary ch ain was 47.44 Gy. Group II comprised 14 patients that received tangent ial portals that did not directly target the internal mammary chain re gion; the average radiation dose was 48.21 Gy to the chest wall, No st atistical difference was observed in group I between the irradiated an d nonirradiated side for vessel diameter (p = .8631) or peak systolic velocity (p = .2646), However, an increase in blood now on the irradia ted side was significant (p = .0321), In evaluating group II alone in addition to the study population (28 patients), we failed to identify significant differences in these parameters. In conclusion, radiation portals that specifically target the internal mammary chain region may affect blood flow but did not have a statistical effect on vessel dia meter and peak systolic velocity. Tangential radiation portals, which may or may not include the internal mammary chain region, appear to ha ve little effect on the internal mammary artery, From these indirect m easurements of internal mammary chain patency, prior radiotherapy may not preclude the use of the ipsilateral muscle as a possible vascular source for pedicled transverse rectus abdominis musculocutaneous flap breast reconstruction.