Indigo aspiration thrombectomy for treating acute lower limb ischemia. Technical considerations

We have read with great interest the recently reported article by Lopez et al1 regarding their experience with Indigo System (IS; Penumbra, Alameda, Calif) aspiration thrombectomy for acute lower limb ischemia (ALLI) with a technical success rate of 52%. The study by Lopez et al1 is one of the first single-center experiences after the well-known PRISM trial.2 In the PRISM trial, the success of the procedures was reported using the Thrombolysis in Myocardial Infarction score,3 allowing for an objective evaluation. In contrast, Lopez et al1 selected the definition of technical success as blood flow restoration to the ischemic limb with <50% residual thrombus, and as they stated, this measurement could be perceived as subjective. The IS consists of an aspiration pump, five different aspiration catheters ranging from 3.4F to 8F, and a separator wire. These intrinsic characteristics lead to some technical considerations that were not described in their report, such as the type of device used in different vessels and whether they had used the separator wire. In our experience, the choice of the caliber of the CAT device is of crucial importance for clot removal and, in particular, in the femoral district in which a mismatch can be present between the vessel diameter and device size. Regarding the separator, our impression has been that it can help in the case of a larger clot by allowing for catheter patency during the aspiration maneuver. Another technical aspect we would like to focus on is the vascular access to be used: the antegrade or retrograde approach with short or long sheaths. We think that the antegrade common femoral artery approach, even for the CAT8 catheter, should be preferred when possible because it increases overall control of the endovascular devices. A main issue when treating patients with ALLI is symptom onset. Using the IS, we can observe the benefits of early treatment after symptoms have appeared. In conclusion, the IS device is very promising for treating ALLI; however, the optimal treatment time and standardization of the techniques should be determined.