ABSTRACT
The knowledge of tissue perfusion has not only a prognostic value in microvascular surgery but also the intraoperative detection of malperfusion can lead to a quick surgical intervention. Indocyanine green (ICG) angiography allows a topographic analysis of perfusion and is used to assess lymphatic drainage pathways and to analyse the depth of burn injuries. Integrating the technique into an operating microscope enables visualisation of the flow over microanastomoses and allows the assessment of the transit time of blood flow between arterial and venous anastomosis. Using this method we analysed 11 microsurgical free flaps (3 latissimus dorsi, 3 rectus abdominis, 1 gracilis muscle, 2 radial forearm, 1 ALT, and 1 DIEP flap). The topographic analysis was performed after the assessment of the microanastomoses. We observed no flap loss or partial flap necrosis. The transit time between arterial inflow and venous outflow was 32.8 s on average. Here we observed distinct differences between muscle flaps (27.7 s) on the one hand and fasciocutaneous and perforator flaps (47.5 s) on the other hand. We detected one venous thrombosis by ICG angiography in a case where the clinical patency test was not distinct. Revision was performed immediately. Particularly for intraoperative assessment, ICG angiography is a useful, reliable and safe technique. The integration into the operating microscope allows an "angiographic patency test" and the analysis of the transit time allows the evaluation of blood flow within the flap. Especially when planning perforator flaps the method of ICG angiography provides a new level of safety in flap design by quickly demonstrating the borders of perfusion.
