Propensity-matched analysis does not support angiosome-guided revascularization of multilevel peripheral artery disease (PAD)

Background: This retrospective comparative cohort study evaluated the clinical outcome of angiosome-guided endovascular arterial reconstructions in chronic limb-threatening ischemia (CLTI) due to multilevel peripheral artery disease (PAD). Methods: Patients treated in an endovascular fashion for CLTI with tissue loss due to multilevel PAD were analyzed. Limbs were classified as having undergone either angiosome-guided (direct) revascularization (DR) or nonangiosomic (indirect) revascularization (IR). DR was defined as uninterrupted in-line flow to the affected angiosome, revascularization through the pedal arch was also considered direct. Groups were adjusted with propensity score (PS) matching and compared for amputation-free survival (AFS), freedom from major adverse limb events (MALE), and healing rate at 12 months. Results: A total of 174 patients (81 men, mean age 70.0 ± 10.4 y) were included. PS matching produced two groups of 55 patients each: DR (24 men, mean age 71.7 ± 10.7 y) and IR (26 men, mean age 72.0 ± 9.4 y). The matched groups had no significant differences in baseline variables. At 12 months there were no significant differences in AFS (73.2% vs 71.6%; p = 0.841), freedom from MALE (71.7% vs 66.1%; p = 0.617), and healing rate (72.7% vs 72.0%; p = 1.000) between DR and IR, respectively. Conclusion: This study failed to support the use of angiosome concept in CLTI due to multilevel disease.

COVID-19-Related Spontaneous Aortic Arch Thrombus With Delayed Embolization

Presentation of a 62-year-old man with baseline chronic obstructive pulmonary disease admitted to the hospital with dyspnea and newly diagnosed COVID-19 infection. CT scan of the chest was obtained to rule out pulmonary embolism. This revealed a mural thrombus of the inner curvature of the aortic arch with a floating component. Therapeutic full dose anticoagulation was initiated in combination with close clinical observation and treatment for modest hypoxia. He did well for 1 month and then returned with ischemic rest pain of the right foot. Angiography revealed thrombosis of all 3 tibial arteries in the right leg. Percutaneous mechanical thrombectomy with tissue plasminogen activator injection and angioplasty was performed with success in 1 tibial artery to achieve in line flow to the foot. After continued anticoagulation, the remainder of the tibial arteries autolysed and the aortic thrombus was noted to be resolved 4 months later. A brief pathophysiology discussion is included.

A Computationally Improved Heuristic Algorithm for Transmission Switching Using Line Flow Thresholds for Load Shed Reduction

A computationally improved algorithm to find the best transmission switching (TS) candidate for load shed reduction after (<i>N</i>-2) contingencies is presented. TS is a planned line outage and research from the past shows that changing transmission system's mesh topology changes the power flows and removes post contingency violations (PCVs). One of the major challenges is to find the best TS candidate in a suitable time. Here, the best TS candidate is determined by using a novel heuristic method by decreasing the search space based on proximity to load shedding bus (LSB). The proposed method is capable of finding the best TS candidate faster than the well-known existing algorithm in the literature and guarantees removal of PCVs. Moreover, proposed algorithm is compatible with both AC and DC optimal power flow (OPF) formulations. Finally, the proposed method is implemented by modifying the topology of the transmission system after (<i>N</i>-2) contingencies in the IEEE 39-bus, IEEE 118-bus, and Polish 2383-bus test systems. Two metrics are used to compare results from the proposed method with those from state-of-the-art to show the speedup and accuracy achieved. Parallel computing is used to increase the computational performance of the proposed algorithm.

A Computationally Improved Heuristic Algorithm for Transmission Switching Using Line Flow Thresholds for Load Shed Reduction

A computationally improved algorithm to find the best transmission switching (TS) candidate for load shed reduction after (<i>N</i>-2) contingencies is presented. TS is a planned line outage and research from the past shows that changing transmission system's mesh topology changes the power flows and removes post contingency violations (PCVs). One of the major challenges is to find the best TS candidate in a suitable time. Here, the best TS candidate is determined by using a novel heuristic method by decreasing the search space based on proximity to load shedding bus (LSB). The proposed method is capable of finding the best TS candidate faster than the well-known existing algorithm in the literature and guarantees removal of PCVs. Moreover, proposed algorithm is compatible with both AC and DC optimal power flow (OPF) formulations. Finally, the proposed method is implemented by modifying the topology of the transmission system after (<i>N</i>-2) contingencies in the IEEE 39-bus, IEEE 118-bus, and Polish 2383-bus test systems. Two metrics are used to compare results from the proposed method with those from state-of-the-art to show the speedup and accuracy achieved. Parallel computing is used to increase the computational performance of the proposed algorithm.

Multi-Fuel Power Dispatch Considering Prohibited Operating Zones and Tie-Line Flow Limits Using Ant Lion Optimizer

The electrical power generation from fossil fuel releases several contaminants into the air, and these become excrescent if the generating unit is fed by multiple fuel sources (MFS). The ever more stringent environmental regulations have forced the utilities to produce electricity at the cheapest price and the minimum level of pollutant emissions. The restriction in generator operations increases the complexity in plant operations. The cost effective and environmental responsive operations in MFS environment can be recognized as a multi-objective constrained optimization problem. The ant lion optimizer (ALO) has been chosen as an optimization tool for solving the MFS dispatch problems. The fuzzy decision-making mechanism is integrated in the search process of ALO to fetch the best compromise solution (BCS). The intended algorithm is implemented on the standard test systems considering the prevailing operational constraints such as valve-point loadings, CO2 emission, prohibited operating zones and tie-line flow limits.

Comparative Analysis on Optimal Placement of TCSC under Single Line Contingency by Using PSO and GA

In the network contingencies, the branch overloading and voltage violation are the most serious conditions and may lead to security problems. The application of Thyristor Controlled Series Capacitor (TCSC) can provide the required apparent reactance smoothly and rapidly and can reduce network contingency problems. This paper focuses an application of Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) to find out the optimal locations of TCSC devices under single contingency to reduce the voltage drops at system buses and line flow improvement on transmission lines. The suitability of the proposed technique is examined on Myanmar Electric Power System. The optimized location provided by each method is applied to single line contingency condition and the responses are observed. According to the simulation results, PSO method can provide the better the stability performance under single line contingency.