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BACKGROUND: Reliability of free flap breast reconstruction has been well established. Thrombophilic conditions may be considered as relative contraindications to free tissue transfer. Sickle cell disease is characterized by the preponderance of abnormal hemoglobin (HbS) which leads to conditions resulting from vaso-occlusion and hemolysis. Sickle cell trait (SCT) is the heterozygous condition in which the majority of hemoglobin molecules are normal, but a substantial percentage of HbS is present. Patients with SCT are asymptomatic until provoked by severe hypoxic conditions, acidosis, and/or hypothermia that cause a marked structural change in HbS, causing vaso-occlusive events similar to those seen in patients with sickle cell disease. There is an obligatory ischemic period during free tissue transfer. There is limited data regarding success rates of free tissue transfer in patients with SCT.
METHODS: A review of all patients who underwent free tissue transfer between June 2011 and May 2013 identified two patients with SCT. Both patients underwent unilateral immediate DIEP flap breast reconstruction.
RESULTS: Patient 1 had an uneventful intra-operative and post-operative course. Patient 2 was morbidly obese (BMI 48), and had a size discrepancy between the epigastric and internal mammary veins. Nonetheless, the vascular anastomoses were performed without event. Approximately two hours after the ischemic period, early onset venous congestion was noted. Both venous and arterial anastomoses were patent, but the venous congestion progressed. There appeared to be poor flow through the flap suggestive of a no re-flow phenomenon. The reconstruction was ultimately abandoned.
CONCLUSIONS: Most free flap failures, especially intra-operative failures, are the consequence of technical errors. However, in some circumstances the etiology of flap failure is unclear. In these cases, failure may be multifactorial. A previous report documented unilateral flap failure in a SCT patient who underwent bilateral free TRAM flap breast reconstruction. The flap that failed was placed on ice during the ischemic period. It is possible that hypothermia precipitated sickling of the abnormal red cells. This hypothermia alone generally does not cause flap failure. A multiple hit etiology of flap failure may explain the case presented. Although technical error cannot be excluded in our patient, it may be possible that this patient with a large flap volume and marginal venous drainage suffered relative intra-flap hypoxia and acidosis causing microvascular thrombosis. The actual impact of SCT on free tissue transfer is limited by the low incidence of flap failure and the limited prevalence of SCT. Nonetheless, SCT should be considered during consultation.