Foot skin blood flow following infrainguinal revascularization for critical lower limb ischemia

Determination of Changes in Tissue Perfusion at Home with Hyperspectral and Thermal Imaging in the First Six Weeks after Endovascular Therapy in Patients with Peripheral Arterial Disease

The aims of this study were to assess changes in tissue perfusion up to 6 weeks after endovascular therapy (EVT), in hospital and at home, and to determine differences in tissue perfusion between patients with and without clinical improvement or good angiographic result. This single-center prospective cohort study included patients undergoing EVT for Rutherford stages two to six. Hyperspectral and thermal imaging were performed at the dorsal and plantar sides of the foot. These measurements consisted of a baseline measurement pre-EVT, and six follow-up measurements obtained at 1 and 4 h and 6 weeks in hospital, and 1 day, 7 days, and 14 days at home. Clinical improvement was defined as a decrease of one or more Rutherford class or decrease in the wound surface area and a good angiographic result was accomplished when a Transatlantic Inter-Society Consensus for the Management of PAD II C or D lesion was treated and uninterrupted flow continued in at least one below-the-knee artery in continuation with the inframalleolar arteries. The study included 34 patients with 41 treated limbs. Deoxyhemoglobin values were lower 1 h post-EVT compared with baseline and increased over time up to 6 weeks post-EVT. Significant differences in deoxyhemoglobin levels at 7 and 14 days post-EVT were determined between patients with and without clinical or angiographic success. This prospective pilot study shows the feasibility of hyperspectral imaging and thermal imaging post-EVT at home, which may decrease the need for hospital visits.

The Effect of Lower Limb Revascularization on Flow, Perfusion, and Systemic Endothelial Function: A Systematic Review

Peripheral arterial disease (PAD) is associated with reduced lower limb blood flow and tissue perfusion. The consequent reduction in vessel wall shear stress as well as ischemia-reperfusion injury has also been associated with systemic endothelial dysfunction and inflammation. We aimed to explore the impact of lower limb revascularization on (1) lower limb blood flow, (2) tissue perfusion, and (3) systemic endothelial function. We performed a systematic literature search using the MEDLINE, Embase, and Web of Science databases. Eligible studies measured changes in lower limb blood flow, perfusion, or systemic endothelial function following revascularization for the treatment of symptomatic PAD. We found 19 eligible studies, which were limited by considerable heterogeneity. Current evidence suggests that revascularization has a positive effect on flow, perfusion, and systemic endothelial dysfunction. Any changes may take a number of weeks to become apparent. There is a need for well-designed studies to explore the association between flow, perfusion, and endothelial dysfunction.

Increase in skin perfusion pressure predicts amputation-free survival after lower extremity bypass surgery for critical limb ischemia

The objective of this study was to determine how postoperative skin perfusion pressure (SPP) as a measure of blood flow after revascularization affects limb prognosis in patients with critical limb ischemia (CLI). We retrospectively reviewed 223 consecutive bypass surgery cases performed in 192 patients with CLI during a 10-year period. SPP was measured 1–2 weeks before and after the procedure. An SPP of 40 mmHg was set as the cut-off value for revascularization. Patients were grouped according to their postoperative SPPs, and amputation-free survival (AFS) was analyzed. An SPP of ≥ 40 mmHg was recovered in 75% of the patients, but no significant difference was found between this group and the group that did not reach 40 mmHg. On the other hand, the values increased by ≥ 20 mmHg from the preoperative values in 70% of the patients. This group had a significantly better AFS than the group that did not increase by 20 mmHg. Logistic regression analysis revealed that (1) a preoperative SPP of < 20 mmHg and (2) a high serum albumin level (> 3.0 g/dL) were significant factors in increasing SPP by 20 mmHg. These results showed that an increase in SPP of ≥ 20 mmHg after bypass surgery was associated with better limb prognosis.

The evaluation of contralateral foot circulation after unilateral revascularization procedures using indocyanine green angiography

The aim of the present study is to assess the effects of unilateral revascularization on the contralateral foot circulation using indocyanine green (ICG). From January 2016 to April 2016, a total of twenty-one patients were included in this study. The patients underwent elective unilateral revascularization at our institution and we evaluated the feet circulation by indocyanine green angiography (ICGA) tests preoperatively and postoperatively. The ICGA parameters included the magnitude of intensity from the onset of ICG to the maximum intensity (I_max), the time from the onset of ICG to the maximum intensity (T_max), and the time required to reach the half maximum intensity from the onset of ICG (T_1/2). There were significant differences in the treated limb T_max (P = 0.016) and T_1/2 (P = 0.013) values and in the contralateral limb T_max (P = 0.013), and T_1/2 (P < 0.001) values on the perioperative ICGA tests. These results reflect the increase in skin perfusion in the treated limb and the decrease in skin perfusion in the contralateral limb. Unilateral revascularization decreases contralateral foot circulation. The preoperative contralateral lesion should be evaluated when revascularization is performed.

Effect of direct cold atmospheric plasma (diCAP) on microcirculation of intact skin in a controlled mechanical environment

OBJECTIVE

The microcirculatory response of intact human skin to exposure with diCAP for different durations with a focus on the effect of implied mechanical pressure during plasma treatment was investigated.

METHODS

Local relative hemoglobin, blood flow velocity, tissue oxygen saturation, and blood flow were monitored noninvasively for up to 1 hour in 1-2 mm depth by optical techniques, as well as temperature, pH values, and moisture before and after skin stimulation. The experimental protocol (N = 10) was set up to differentiate between pressure- and plasma-induced effects.

RESULTS

Significant increases in microcirculation were only observed after plasma stimulation but not after pressure stimulus alone. For a period of 1 h after stimulation, local relative hemoglobin was increased by 5.1% after 270 seconds diCAP treatment. Tissue oxygen saturation increased by up to 9.4%, whereas blood flow was doubled (+106%). Skin pH decreased by 0.3 after 180 seconds and 270 seconds diCAP treatment, whereas skin temperature and moisture were not affected.

CONCLUSIONS

diCAP treatment of intact skin notably enhances microcirculation for a therapeutically relevant period. This effect is specific to the plasma treatment and not an effect of the applied pressure. Prolonged treatment durations lead to more pronounced effects.

PET/SPECT imaging of hindlimb ischemia: focusing on angiogenesis and blood flow

Peripheral artery disease (PAD) is a result of the atherosclerotic narrowing of blood vessels to the extremities, and the subsequent tissue ischemia can lead to the up-regulation of angiogenic growth factors and formation of new vessels as a recovery mechanism. Such formation of new vessels can be evaluated with various non-invasive molecular imaging techniques, where serial images from the same subjects can be obtained to allow the documentation of disease progression and therapeutic response. The most commonly used animal model for preclinical studies of PAD is the murine hindlimb ischemia model, and a number of radiotracers have been investigated for positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of PAD. In this review article, we summarize the PET/SPECT tracers that have been tested in the murine hindlimb ischemia model as well as those used clinically to assess the extremity blood flow.