Foot perfusion. Insights from an anatomically detailed arterial network model.

Abstract

Peripheral artery disease currently affects over 202 million people worldwide. The ankle-brachial index is widely used to assess a reduction in blood flow to the foot, but it cannot characterise tissue perfusion. MRI-based perfusion measurements can provide this information, yet they are time-consuming and can be painful if induction of ischemia is warranted for the scan. As an alternative, we model foot perfusion during a cuff-induced ischemia test to characterise how arterial occlusions affect perfusion in foot regions. Simulations, not patient-specific at this stage, are conducted on a 1D arterial network model which includes 154 foot and calf arterial segments, providing a realistic description of the topology of the foot vasculature. A baseline model characterizes angiosome perfusion under healthy conditions, which is then modified to reflect 42 pathological scenarios by introducing occlusions and different levels of collateral impairment. This approach enables a novel in-silico comparison of angiosome-targeted and best-vessel strategies in a realistic whole-limb geometry, uncovering mechanistic phenomena relevant for revascularization planning. Results show a marked influence of collateral impairment on angiosome perfusion under the condition of a single-artery occlusion, highlighting the role of blood redistribution. If two feeding arteries are occluded, perfusion markedly decreases at all collateral impairment levels due to the severe reduction in incoming blood flow. These results provide a bridge between the angiosome-targeted and "best-vessel" strategies for revascularization, showing that both can be correct depending on collateral sufficiency.