[What key zones should be monitored as a function of the assessment of the initial lesion? Collateral pathways?].

Key zones to be kept under surveillance are defined as a function of initial lesion features of operated or unoperated arteriopathy of lower limbs. Knowledge of these key zones resides in the anatomical knowledge of the supply network and of the physiopathology involved and its coming into play. Collateral circulations of infrarenal aortic obstructions are studied in detail, and then those that develop after femoral and tibial artery occlusions. Valid prediction of the ischemic risk can only be made after obtaining precise data on the re-entry effectiveness through this collateral circulation, allowing a prognosis to be established and a reasoned choice of therapy to be made.