Chronic limb-threatening ischemia (CLTI) is associated with significant mortality and limb loss. The interventional lumbar sympathectomy (LS) is one of the supportive treatment options for CLTI patients, reducing pain intensity and peripheral arterial resistance. The use of LS has gradually declined despite its positive effects. The contradictory results of studies dealing with evidence of tissue perfusion improvement after LS are one of the possible explanations. We describe a new approach for the evaluation of LS efficacy in 2 CLTI patients and below-the-knee arteries pathology in our observational cohort experimental trial. We utilized the angiosome concept of foot. Angiography identified angiosomes with occluded source artery. The relationship between angiosomes and corresponding surface areas of angiosomes-dermatomes was identified. The infrared thermography was used for the measurement of thermal changes in dermatomes before and after LS. Based on the thermal changes in dermatomes and the relationship between angiosomes and their dermatomes, we estimated perfusion in angiosomes after the LS procedure. We found that the clinically relevant increase in temperature (>
1°C) was presented only in dermatomes corresponding to angiosomes with occluded source artery. We hypothesize that LS opens up anastomoses between angiosomes, resulting in redistribution of blood flow between angiosomes that is associated with an increase in temperature in angiosomes with occluded source artery.