Distal pedal bypasses combined with free microsurgical flaps in chronic limb ischaemia for problematic wounds.

Abstract

We want to congratulate De Caridi and coauthors for their description of the value of what they called an extreme distal bypass to improve wound healing in Buerger's disease 1. They describe the successful management of a 53-year-old patient with thromboangiitis obliterans (TAO/Buerger's disease), which is a rare non-atherosclerotic inflammatory disease and they highlight the value of distal peripheral bypass surgery in such occasions. Although this is only a single case report, it has been shown that beyond the successful treatment of an infected wound in a poorly vascularised extremity, such surgical approaches with limb salvage after successful pedal bypass grafting are associated with improved long-term survival 2. Studies concerning the long-term morbidity and mortality after reconstruction for critical limb ischaemia following pedal bypasses with often multiple operative or interventional steps show high rates of primary and secondary patency. But when amputation becomes necessary this is associated with significantly worse long-term survival 2. We want to add our experiences with distal pedal branch bypasses over the last 20 years for limb salvage, where we found a number of technical factors that may be associated with graft patency and limb salvage 3 (Figures 1, 2). The indication for distal pedal bypass grafts has become an accepted treatment form for all patients who suffer from peripheral arterial occlusive disease, limb-threatening peripheral ischaemia and wounds with or without major infections. We found that the preoperative assessment and the accuracy of imaging diagnostics is a prerequisite for proper planning of how to proceed, and we could not identify a typical systemic contraindication, because the results were unaltered regardless of age or diabetic status. However, there are a number of problematic wounds with exposed vital structures where neither vascular surgery alone nor plastic surgery with free flap transplantation is sufficient when applied solely. When distal pedal revascularisation however is combined with simultaneous or staged free microvascular tissue transplantations, new horizons may be opened for patients with such severe wounds as described by De Caridi et al. 4. In cachectic patients in whom no sufficient muscle tissues could be harvested, we have demonstrated the value of the greater omentum as a source of well-vascularised autologous tissue that can be combined with revascularisation processes 5. Surgical principles of radical wound debridement—regardless of underlying vital structures are exposed—and if necessary a second-look operation with intermittent negative pressure wound treatment, simultaneous or staged distal bypass grafting together with soft tissue transfer with an appropriate microvascular flap may help salvage limbs even when heavily infected wounds are present 6, 7. We are aware of the fact that not every vascular unit might have the chance of joining hands with plastic surgeons to tackle combined vascular-plastic reconstructive operative manoeuvers and vice versa. Nevertheless, when the problem of a high resistance in the distal outflow vessel after pedal bypass grafting may be solved by attaching a muscle flap with a completely new capillary bed, the run-off can be influenced significantly. Even when the flap and its microcapillary bed as well as the arterial connection to the flap may occlude over the time, we have seen stable wound coverage over many years with unsuspicious flap tissue in place 4, 6. From these observations, we would like to stress the concept of a nutrient free flap in addition to distal pedal bypass grafts to enhance long-term stable coverage of large tissue loss in ischaemic limbs. Given the safety and durability of these procedures with cumulative foot salvage rates of > 80% at 3–5 years in our series of 76 patients over the last 10 years 3, we conclude that our results justify attempting revascularisation with distal bypass grafting to the foot vessels—with or without additional free flaps—is indicated even in high-risk patients and that such interdisciplinary treatment forms should be deliberated in any of these problematic wounds before major amputation is undertaken. Raymund E Horch, MD1*, Werner Lang, MD2, Alexander Meyer, MD2, Marweh Schmitz, MD1 1Department of Plastic and Hand Surgery University Hospital Erlangen Erlangen, Germany 2Division of Vascular Surgery University Hospital Erlangen Erlangen, Germany *Email: raymund.horch@uk-erlangen.de