The role of foot collateral vessels on angiosome-oriented revascularization

Comprehensive imaging of microcirculatory changes in the foot during endovascular intervention - A technical feasibility study

Chronic limb-threatening ischemia (CLTI) has a major impact on patient's lives and is associated with a heavy health care burden with high morbidity and mortality. Treatment by endovascular intervention is mostly based on macrocirculatory information from angiography and does not consider the microcirculation. Despite successful endovascular intervention according to angiographic criteria, a proportion of patients fail to heal ischemic lesions. This might be due to impaired microvascular perfusion and variations in the supply to different angiosomes. Non-invasive optical techniques for microcirculatory perfusion and oxygen saturation imaging have the potential to provide the interventionist with additional information in real-time, supporting clinical decisions during the intervention. This study presents a novel multimodal imaging system, based on multi-exposure laser speckle contrast imaging and multi-spectral imaging, for continuous use during endovascular intervention. The results during intervention display spatiotemporal changes in the microcirculation compatible with expected physiological reactions during balloon dilation, with initially induced ischemia followed by a restored perfusion, and local administration of a vasodilator inducing hyperemia. We also present perioperative and postoperative follow-up measurements with a pulsatile microcirculation perfusion. Finally, cases of spatial heterogeneity in the observed oxygen saturation and perfusion are discussed. In conclusion, this technical feasibility study shows the potential of the methodology to characterize changes in microcirculation before, during, and after endovascular intervention.

Indirect Endovascular Revascularization via Collaterals: A New Classification to Predict Wound Healing and Limb Salvage

BACKGROUND

In the setting of chronic limb ischemia, lower extremity (LE) wounds require revascularization of source arteries for wound healing and limb salvage. Direct revascularization of the source artery is preferred but cannot always be performed. Our objective was to analyze the influence of arterial-arterial connections on clinical outcomes after angiosome-directed endovascular revascularization.

METHODS

Consecutive LE wounds in patients with isolated infra-popliteal disease revascularized endovascularly from 2012 to 2016 within a single center were retrospectively reviewed. Treatment was classified as direct revascularization (DR) if the source artery supplying the wound angiosome was treated, indirect revascularization via collaterals (IR-C) if the source artery angiosome was revascularized by another major artery via arterial connections, or indirect revascularization (IR) if direct revascularization of the source artery angiosome was not possible. Demographics, comorbidities, and patient outcomes were collected.

RESULTS

Of 105 patients with 106 LE wounds, there were 35, 38, and 33 patients in the DR, IR-C, and IR groups, respectively. The mean age was 65.8 years old (standard deviation (SD) 11.9) with 81 males (77.1%) and 24 females (22.9%). Average follow-up was 21.0 months (SD 14.0). Overall wound healing rates were 80.0%, 92.1%, and 63.6% for DR, IR-C, and IR, respectively (P = 0.009). Significant differences were found between all 3 group comparisons, DR versus IR-C (P = 0.010), DR versus IR (P = 0.013), IR-C versus IR (P = 0.008). Overall major amputation-free survival was 85.7%, 89.5%, and 69.7% in DR, IR-C, and IR groups, respectively, with statistically significant differences between the IR-C and IR groups (P = 0.036).

CONCLUSIONS

Treating diseased infra-popliteal arteries and improving blood flow via arterial-arterial connections as per the angiosome model improved wound healing and amputation-free survival in this cohort. Although DR is still the gold standard, revascularization using IR-C may give superior healing results even in highly comorbid patients. This offers an additional avenue for treatment, especially when DR is not possible.

Foot Angiosomes: Instructions for Use

In the last 15 years an abundance of literature has demonstrated that angiosome-targeted revascularization, either endovascular or open, can lead to better clinical results in patients with chronic limb-threatening ischemia. According to this literature, the angiosome concept should guide our treatment strategy in every chronic limb-threatening ischemia patient. However, in our daily practice, its application is often difficult or impossible. Most foot wounds spread over multiple angiosomes and, moreover, the value of an angiosome-guided revascularization approach can vary according to vascular anatomy, collateral vessel network, type of revascularization, and wound. The aim of this article is to explore values and limits of the angiosome concept, and to propose some “instructions for use” regarding its application in our daily practice.