Best crossing of peripheral chronic total occlusions.

Together with colleagues from different disciplines, including cardiologists, interventional radiologists and vascular surgeons, committee members of the of the German Society of Angiology ( []), developed a novel algorithm for the endovascular treatment of peripheral chronic total occlusive lesions (CTOs). Our aim is to improve patient and limb related outcomes, by increasing the success rate of endovascular procedures. This can be achieved by adherence to the proposed crossing algorithm, aiding the standardization of endovascular procedures. The following steps are proposed: (i) APPLY Duplex sonography and if required 3D techniques such as computed tomography or magnetic resonance angiography. This will help you to select the optimal access site. (ii) EVALUATE the CTO cap morphology and distal vessel refilling sites during diagnostic angiography, which are potential targets for a retrograde access. (iii) START with antegrade wiring strategies including guidewire (GW) and support catheter technology. Use GW escalation strategies to penetrate the proximal cap of the CTO, which may usually be fibrotic and calcified. (iv) STOP the antegrade attempt depending on patient specific parameters and the presence of retrograde options, as evaluated by pre-procedural imaging and during angiography. (v) In case of FAILURE, consider advanced bidirectional techniques and reentry devices. (vi) In case of SUCCESS, externalize the GW and treat the CTO. Manage the retrograde access at the end of the endovascular procedure. (vii) STOP the procedure if no progress can be obtained within 3 hours, in case of specific complications or when reaching maximum contrast administration based on individual patient's renal function. Consider radiation exposure both for patients and operators. In this manuscript we systematically follow and explain each of the steps (i)-(vi) based on practical examples from our daily routine. We strongly believe that the integration of this algorithm in the daily practice of endovascular specialists, can improve vessel and patient specific outcomes.