2D perfusion-angiography during endovascular intervention for critical limb threatening ischemia - A feasibility study

Association of 2D Perfusion Angiography and Wound Healing Rate in Combined Femoro-popliteal and Below-the-Knee Lesions in Ischemic Patients Undergoing Isolated Femoro-popliteal Endovascular Revascularization

The aim of this study was to demonstrate the association between 2-dimensional (2D) perfusion angiography and wound healing rate in patients with combined femoro-popliteal and below-the-knee lesions in critical limb-threatening ischemia (CLTI) and foot wounds undergoing isolated femoro-popliteal endovascular revascularization. Between January and June 2019, 24 patients with multilevel CLTI and foot wounds underwent isolated femoro-popliteal endovascular revascularization. In all of them, an assessment of foot perfusion by 2D perfusion angiography was performed. To evaluate the foot perfusion, a region of interest was identified, and time-density curves were calculated. Changes of the overall time-density curves were evaluated together with transcutaneous oximetry (TcPO2) using bivariate correlation (Pearson correlation coefficient) and associated with 6-month wound healing. The mean increase of time-density curves was 212.2% (range from +9.8% to +1984.9%) and the mean increase of TcPO2 was 116.4% (range from -4.7% to 485.7%). No significant association between time-density curves and TcPO2 values (Pearson correlation coefficient: -0.24) was observed (P = .3). At 6 months, wound healing occurred in 15 of 24 (62.5%) patients. In conclusion, this preliminary experience confirmed that 2D perfusion angiography associates with wound healing rate in CLTI patients with ischemic foot wounds and combined femoro-popliteal and below-the-knee lesions who are undergoing isolated femoro-popliteal endovascular revascularization. No association between time-density curves and TcPO2 values was observed.

Evaluation of Tissue Perfusion by Wound Blush and 2D Color-Coded Digital Subtraction Angiography During Endovascular Intervention and Its Impact on Limb Salvage in Critical Limb Ischemia

PURPOSE

Critical limb ischemia (CLI) is an entity with high mortality if not properly treated. The primary aim of CLI revascularization is to enhance wound healing, which greatly depends on microvascular circulation. The available tools for assessment of revascularization success are deficient in the evaluation of local microvascular tissue perfusion, that wound blush (WB) reflects. A reliable technique that assesses capillary flow to foot lesions is needed. This study aims to assess WB angiographically at sites of interest in the foot after revascularization and its impact on limb salvage in CLI.

MATERIALS AND METHODS

198 CLI patients (Rutherford category 5/6) with infrainguinal atherosclerotic lesions amenable for endovascular revascularization (EVR) were included. Limbs were directly or indirectly revascularized by EVR. Direct revascularization meant that successful revascularization of the area of interest according to the angiosome concept was achieved. A completion angiographic run was taken to assess WB. Patients were divided into 2 groups; positive and negative WB groups. In the event of a disagreement between the observational investigators, the digital subtraction angiography (DSA) series was analyzed for hemodynamic changes with a computerized 2D color-coded DSA (Syngo iFlow).

RESULTS

176 limbs had successful revascularization in 157 patients. The successful revascularization rate was 88.9% (176/198), with technical failure encountered in 22 limbs. 121 patients had positive WB and 55 patients had negative WB. Direct revascularization of target areas was obtained in 98 limbs (55.7%). There was a significant difference in the rate of achieving direct flow to the lesion between the positive WB and negative WB groups (36.4% vs 19.3%, p≤0.001). We noticed a nonsignificant difference between patients who had direct revascularization of the foot lesion(s) and those who had indirect revascularization as regards limb salvage. Patients were followed up for 25.2 ± 12.7 months. By the end of the first year, limb salvage rate was significantly higher in patients who had positive WB (98% vs 63%, p<0.001, after 2 years (97% vs 58%, p<0.001) and after 3 years (94% vs 51.5%, p<0.001).

CONCLUSIONS

WB is an important predictor and a prognostic factor for wound healing in CLI patients with soft tissue lesions.

The Efficacy of Cone-Beam CT-Based Perfusion Mapping in Evaluation of Tissue Perfusion in Peripheral Arterial Disease

This study investigated the use of cone-beam computed tomography (CBCT)-based perfusion mapping during percutaneous transluminal angioplasty (PTA) to predict clinical outcome in the peripheral arterial disease (PAD). From January 2016 to March 2020, 43 patients (28 male, 15 female; mean age, 69) with 51 limbs, who underwent PTA with CBCT-based foot perfusion mapping for PAD were included. Parenchymal blood volume (PBV) of foot was measured. Clinical response was investigated based on medical records. Predictive value for clinical success was evaluated using multiple logistic regression with C-statistics. Two reviewers visually assessed the improvement on angiography and CBCT-based foot perfusion mapping; inter-observer agreement of clinical success between the two were measured. Technical and clinical success rate of PTA was 90.8% and 68.6%, respectively. In multiple logistic regression, the maximum value of PBV (PBV_max) on perfusion mapping after PTA was significant (p = 0.03) for evaluating clinical success with the highest C-statistic (0.84). Using a cutoff of 235.7 mL/L for PBV_max after PTA, area under curve for prediction of clinical success was 0.664, and sensitivity and specificity were 71.4% and 68.8%, respectively. Consistency in prediction of clinical success between the two reviewers was almost perfect for CBCT-based foot perfusion mapping.

2D perfusion DSA with an open-source, semi-automated, color-coded software for the quantification of foot perfusion following infrapopliteal angioplasty: a feasibility study

BACKGROUND

Foot perfusion has been recently implemented as a new tool for optimizing outcomes of peripheral endovascular procedures. A custom-made, two-dimensional perfusion digital subtraction angiography (PDSA) algorithm has been implemented to quantify outcomes of endovascular treatment of critical limb ischemia (CLI), assist intra-procedural decision-making, and enhance clinical outcomes.

METHODS

The study was approved by the Hospital's Ethics Committee. This prospective, single-center study included seven consecutive patients scheduled to undergo infrapopliteal endovascular treatment of CLI. Perfusion blood volume (PBV), mean transit time (MTT), and perfusion blood flow (PBF) maps were extracted by analyzing time-intensity curves and signal intensity on the perfused vessel mask. Mean values calculated from user-specified regions of interest (ROIs) on perfusion maps were employed to evaluate pre- and post-endovascular treatment condition. Measurements were performed immediately after final PDSA.

RESULTS

In total, five patients (aged 54 ± 16 years, mean ± standard deviation) were analyzed, as two patients were excluded due to significant motion artifacts. Post-procedural MTT presented a mean decrease of 19.1% for all patients and increased only in 1 of 5 patients, demonstrating in 4/5 patients an increase in tissue perfusion after revascularization. Overall mean PBF and PBV values were also analogously increased following revascularization (446% and 69.5% mean, respectively) and in the majority of selected ROIs (13/15 and 12/15 ROIs, respectively).

CONCLUSIONS

Quantification of infrapopliteal angioplasty outcomes using this newly proposed, custom-made, intra-procedural PDSA algorithm was performed using PBV, MTT, and PBF maps. Further studies are required to determine its role in peripheral endovascular procedures ( ClinicalTrials.gov Identifier: NCT04356092).