Acute Limb Ischemia: An Update on Diagnosis and Management

Surgical thrombectomy versus conservative treatment in cases of acute limb ischemia with COVID-19 pneumonia

COVID-19 infection is a major cause for acute respiratory distress syndrome, multi-organ dysfunction, coagulopathy, and intravascular thrombosis; therefore, it is the main causative factor for acute limb ischemia.

Aim. To compare the treatment outcome of two limb ischemic groups post COVID-19 infection in a single center and detect at least which is better for the patients in the period of COVID-19 pandemic.

Material and methods. Here, in this study, we collect 26 patients and divided them into two groups, G1 (14) patients treated conservatively and G2 (12) patients treated with surgical thrombectomy. Data were analyzed to look for the outcome of groups after 24 hours and 30 days.

Results. The successful rate of conservative treatment was 85,72% in G1, while it was 75% in G2. There were two amputations below the knee joint in each group. Three patients died in both groups.

Conclusion. In conclusion, both conservative treatment and surgical thrombectomy have a comparable successful rate in the selected group of COVID-19 patients.

Fibrin Clot Properties in Atherosclerotic Vascular Disease: From Pathophysiology to Clinical Outcomes

Fibrin is a major component of thrombi formed on the surface of atherosclerotic plaques. Fibrin accumulation as a consequence of local blood coagulation activation takes place inside atherosclerotic lesions and contributes to their growth. The imbalance between thrombin-mediated fibrin formation and fibrin degradation might enhance atherosclerosis in relation to inflammatory states reflected by increased fibrinogen concentrations, the key determinant of fibrin characteristics. There are large interindividual differences in fibrin clot structure and function measured in plasma-based assays and in purified fibrinogen-based systems. Several observational studies have demonstrated that subjects who tend to generate denser fibrin networks displaying impaired clot lysis are at an increased risk of developing advanced atherosclerosis and arterial thromboembolic events. Moreover, the majority of cardiovascular risk factors are also associated with unfavorably altered fibrin clot properties, with their improvement following effective therapy, in particular with aspirin, statins, and anticoagulant agents. The prothrombotic fibrin clot phenotype has been reported to have a predictive value in terms of myocardial infarction, ischemic stroke, and acute limb ischemia. This review article summarizes available data on the association of fibrin clot characteristics with atherosclerotic vascular disease and its potential practical implications.

Ischemic postconditioning ameliorates acute kidney injury induced by limb ischemia/reperfusion via transforming TLR4 and NF-κB signaling in rats

BACKGROUND

The present study investigated the influence of ischemic postconditioning (I-postC) on the adjustment of renal injury after limb ischemia-reperfusion (I/R) injury, to elucidate the mechanisms of the Toll-like receptor 4 (TLR 4)/NF-κB signaling pathway using histopathological and immunohistochemical methods.

METHODS

Male Sprague-Dawley rats were randomly assigned to five groups (numbered from 1 to 5): the sham group (Group 1, only the anesthesia procedure was conducted without limb I/R), the I/R group (Group 2, 4 h of reperfusion was conducted following 4 h limb ischemia under anesthesia), the I/R + I-postC group (Group 3, 4 h of ischemia and 4 h of reperfusion was conducted; before perfusion, 5 min of limb ischemia and 5 min of reperfusion were performed in the rats and repeated 3 times), the I/R + TAK group (Group 4, rats were injected with TLR4 antagonist TAK through the caudal vein before limb ischemia and reperfusion under anesthesia), the TAK group (Group 5, rats were injected with TAK, and the anesthesia procedure was conducted without limb I/R). Histological changes in the kidney in different groups were observed, and the extent of tubular injury was assessed. Changes in biochemical indexes and the expression of inflammatory factors, TLR4, and NF-κB were also evaluated.

RESULTS

Compared with rats in the I/R group, the secretion of inflammatory factors and the expression levels of TLR4 and NF-κB were decreased in rats in the I/R + I-postC group. Histological analysis revealed renal injury, including inflammatory cell infiltration, dilatation of the tubuli lumen, congestion in glomerular capillaries, degeneration of tubuli epithelial cells, and necrosis was ameliorated by I-postC. Immunohistochemical studies showed that I/R-induced elevation in TLR4 and NF-κB expression was reduced by I-postC treatment. Moreover, the expression levels of TLR4, NF-κB, and inflammatory factors in rats in the I/R + TAK group were also decreased, and the renal pathological lesion was alleviated, which was similar to that in rats in the I/R + I-postC group.

CONCLUSIONS

The present findings suggest that I-postC can reduce tissue injury and kidney inflammation induced by limb I/R injury, possibly via inhibition of the TLR4 and NF-κB pathways.

Acute Limb Ischemia Complicated by Heparin-Induced Thrombocytopenia in an Asymptomatic COVID-19 Patient

Acute limb ischemia (ALI) is the sudden decrease in limb perfusion caused by embolism secondary to many blood stasis conditions. Treatment commences with intravenous (IV) unfractionated heparin infusion. Individuals can have an immune-mediated reaction to heparin products which results in heparin-induced thrombocytopenia (HIT). Coronavirus disease 2019 (COVID-19) has added to the difficulty of treating patients with ALI due to increasing the likelihood of HIT via the virus's ability to manipulate the coagulation parameters. We present a case of ALI complicated by HIT in a 49-year-old male with a confirmed asymptomatic COVID-19. The patient initially presented with progressive pain, coldness, and tingling in the right foot. He was treated with a tissue plasminogen activator (TPA) and a heparin drip. The occlusion persisted despite medical intervention leading to right below-knee amputation. The patient returned to the emergency department (ED) 13 days later with massive intracranial hemorrhage and subsequently expired. This case study demonstrates the significance of COVID-19 diagnostic testing due to the possibility of developing blood clots and potential complications, including HIT.

A clinical case series of COVID-19-associated acute limb ischemia: real-world situation

BACKGROUND

COVID-19 was a trending topic all year long in 2020. Currently, it is not only a problem for a pulmonologist since it could cause complications to many other organs, including the cardiovascular system. Recent acute COVID-19 infection state has been associated with hypercoagulation and causing microthrombi called immunothrombus. Acute limb ischemia is one of the rare complications but organ-threatening. Unfortunately, unlike coronary artery disease, there is no recent guideline for cardiologists to diagnose and manage acute limb ischemia in pandemic situations CASE PRESENTATION: This case series presented two patients with acute limb injury (ALI)-complicating COVID-19, with chief complaints of pain at their lower extremity. The first patient was an 80-year-old woman who was just dismissed from the hospital due to COVID-19. The distal part of her toe was cyanosed, and her motoric and sensory functions were partially reduced. She was treated with oral drug therapy due to unwillingness to be hospitalized. Interestingly, she had recovered by using oral drug therapy. The second case was a 54-years-old female with several comorbidities such as obesity, type 2 diabetes mellitus, hypertension, dyslipidemia, and chronic obstructive pulmonary disease. She had cyanosed foot and weak arterial pulsation. Unfortunately, she passed away due to acute respiratory distress syndrome.

CONCLUSION

Several internal and external factors cause ALI treatment to be more challenging in the pandemic COVID-19 situation. The diagnosis and management of ALI in COVID-19 patients may not fully comply with the current guideline and are likely to be affected by local hospital regulations. Clinical follow-up might be an essential feature in treating ALI in COVID-19 patients.

Catheter-directed intra-arterial thrombolysis in the treatment of acute thrombosis of below-the-knee arteries

Selecting treatment options in acute arterial thrombosis of the lower extremity, which threatens limb viability, is still a challenge for vascular surgeons. Early restoration of blood flow is crucial and is conducted by surgical thrombectomies or endovascular procedures, depending on patient condition. Catheter-directed thrombolysis with or without percutaneous mechanical thrombectomy for acute limb ischemia has been widely implemented from the early 1990s. Here, we present 2 cases of acute thrombosis of below-the-knee arteries, where we successfully saved the involved limbs using catheter-directed thrombolysis and thrombus aspiration.

Prognostic Value of Charlson Comorbidity Index in Acute Embolic Lower Limb Ischaemia Patients

INTRODUCTION

Charlson Comorbidity Index (CCI) is commonly used in outcome studies to adjust for patient comorbid conditions but has not been specifically validated for use in acute embolic lower limb ischaemia (AELLI).

OBJECTIVES

The aim of this study was to access whether a high CCI score unadjusted (CCIu) and adjusted (CCIa) by age relates to major amputation and mortality after a first episode of AELLI.

METHODS

The last 100 patients presenting with the first event of AELLI submitted to embolectomy at our Vascular Surgery Department were retrospectively evaluated. Patient characteristics, pre- and post-operative period variables were collected and CCIu and CCIa calculated. Survival predictors were analyzed using Cox regression. The area under the curve of the receiver operating characteristic curves was calculated to validate and determine the discriminating ability of CCIu and CCIa in predicting amputation rate and 30-day mortality. Youden index was used to determine the critical value. Survival analysis was performed with Kaplan-Meier method and differences between survival curves were tested with Log-Rank test. A P value of <0.05 was considered statistically significant.

RESULTS

The mean age was 80.03±10.776 years and the mean follow-up 19.28±7.929 months. Amputation rate was 16%, 30-day mortality 21% and long-term mortality 42%. Patients with CCIu≥3 compared with patients with CCIu<3 had higher amputation rate (37.5% vs. 1.7%; OR:35.400), 30-day mortality (47.5% vs. 3.3%; OR:35.400) and global mortality (P=0.00). Also, patients with CCIa≥6 compared with patients with CCIa<6 had higher amputation rate (34.1% vs. 1.8%; OR:28.488), 30-day mortality (47.7% vs. 0.0%) and global mortality (P=0.00). Multivariate analysis showed that both CCIu and CCIa were independent predictors of amputation rate and 30-day mortality.

CONCLUSION

CCIu and CCIa have proven to be good predictors of amputation rate and survival, thus being a valuable prognostic factor in patients presenting with the first event of AELLI.

Successful endovascular therapy for recurrent acute limb ischaemia due to persistent sciatic artery aneurysm after femoropopliteal bypass

Persistent sciatic artery (PSA) is a rare vascular anomaly that can cause acute limb ischaemia (ALI) due to peripheral thromboembolism following aneurysm formation, and surgical repair or exclusion with or without femoropopliteal bypass is the standard treatment for these symptomatic cases of PSA. Here, we report a case of a 70-year-old man with right PSA aneurysm who suffered from recurrent ALI despite the history of right femoropopliteal bypass at the age of 58 for occlusion of right PSA and graft (femoropopliteal bypass graft)-to-tibial bypass at the age of 68 for occlusion of right posterior tibial artery. We performed a catheter angiographic examination using an intravascular ultrasound and performed an endovascular therapy (EVT) for the purpose of jailing the internal iliac artery. This is a rare case of PSA aneurysm presenting with recurrent ALI after femoropopliteal bypass successfully treated with EVT.

A Comparison of Outcomes Based on Vessel Type (Native Artery vs. Bypass Graft) and Artery Location (Below-Knee Artery vs. Non-Below-Knee Artery) Using a Combination of Multiple Endovascular Techniques for Acute Lower Limb Ischemia

BACKGROUND

To evaluate outcomes of endovascular treatment (EVT) using a combination of multiple endovascular techniques for acute lower limb ischemia (ALLI) and to compare outcomes based on vessel type and artery location.

METHODS

A total of 95 consecutive patients with ALLI (mean age, 72.0 years; 65 males; 104 lower limbs) who received emergency EVT using a combination of multiple endovascular techniques including thrombolysis, aspiration thrombectomy, stenting, and balloon angioplasty with or without surgical thromboembolectomy, between January 2005 and December 2017 were included. Vessel type was classified into native artery occlusion (native occlusion) and bypass graft occlusion (graft occlusion), including prosthetic and vein graft. Additionally, native arteries were categorized into below-knee occlusion and non-below-knee occlusion. Technical success, perioperative death (POD), ALLI-related death, amputation, amputation-free survival (AFS), and complications were compared according to vessel type (native occlusion vs. graft occlusion) and artery location (below-knee occlusion vs. non-below-knee occlusion).

RESULTS

Of all patients with ALLI, 16.8% underwent a single endovascular technique, whereas 83.2% underwent a combination of multiple endovascular techniques. The technicalsuccess, POD, and ALLI-related death rates in the total number of patients were 94.7%, 11.6%, and 4.2%, respectively. A total of 67 patients (75 limbs) and 28 patients (29 limbs) were classified as having native occlusion and graft occlusion (prosthetic, 24 limbs; vein, 5 limbs), respectively. No significant differences in technical success (native occlusion: 92.5% vs. graft occlusion: 100%), POD (14.9% vs. 3.6%), and ALLI-related death (6.0% vs. 0%) were noted between native occlusion and graft occlusion. However, the 30-day AFS rate of native occlusion was significantly lower than that of graft occlusion (75.2% vs. 96.3%, P=0.01). The amputation rate (P=0.03) and AFS rate (P=0.03) of below-knee occlusion were significantly worse for below-knee occlusion patients than for non-below-knee occlusion patients.

CONCLUSIONS

EVT using multiple endovascular techniques for ALLI is effective and safe. A combination of multiple endovascular techniques is crucial for successful treatment. However, native occlusion may have a lower AFS rate than graft occlusion, and below-knee occlusion may have a higher risk of amputation than non-below-knee occlusion.

Acute Limb Ischemia as the Initial Severe Presentation in COVID-19

Coronavirus disease 2019 (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is characterized by an overwhelming inflammatory response in a subset of patients, resulting in respiratory compromise, multiorgan failure, and death. A common complication seen in patients hospitalized with COVID-19 infections is the development of venous and arterial thromboemboli. This occurs especially in patients who suffer from severe respiratory or systemic manifestations on the COVID-19 spectrum of disease. We present a case of acute limb ischemia as the initial presentation in a patient who tested positive for COVID-19.

Oral Anticoagulant and Antiplatelet Therapy for Peripheral Arterial Disease: A Meta-analysis of Randomized Controlled Trials

Peripheral artery disease (PAD) is a common disease affecting over 200 million people worldwide. PAD is associated with significant limb and cardiovascular morbidity and mortality which is reduced by antiplatelet and antithrombotic therapy. However, the optimal type, dose, and time of antithrombotic therapy is still uncertain.We searched 4 electronic databases from January 1, 1990, to June 1, 2020, for randomized controlled trials of patients who received oral anticoagulant and antiplatelet therapy for PAD. The primary outcome was a composite of acute limb ischemia, major amputation, myocardial infarction, ischemic stroke, death from cardiovascular events, or death from any cause. Secondary outcomes included major bleeding, fatal bleeding, and intracranial hemorrhage events.We identified 3 studies that satisfied inclusion and exclusion criteria. Compared with antiplatelet alone, oral anticoagulant plus antiplatelet therapy improved acute limb ischemia (p < 0.00001), stroke (p = 0.005), and major amputation events (p = 0.11). However, oral anticoagulant plus antiplatelet therapy was not effective for prevention of myocardial infarction (p = 0.23), death from cardiovascular events (p = 0.65), or death from any cause (p = 0.66). Additionally, a significant increase in major bleeding events was demonstrated (p < 0.00001). There was no significant difference in fatal bleeding (p = 0.16) or intracranial hemorrhage events (p = 0.43). This meta-analysis showed that oral anticoagulant plus antiplatelet therapy for PAD may improve acute limb ischemia and major amputation or stroke risk compared with antiplatelet therapy alone, but could increase the risk of major bleeding events. On the other hand, measuring myocardial infarction, death, fatal bleeding, or intracranial hemorrhage risk remains controversial.

Risk Factors for Fasciotomy After Revascularization for Acute Lower Limb Ischaemia

Background: Acute lower limb ischaemia (ALI) is a life and limb threatening vascular emergency. Acute compartment syndrome (ACS) may develop upon revascularization. The risk of fasciotomy was hypothesized to be decreased in women due to their lower calf muscle mass. The main aim was to evaluate risk factors for fasciotomy after revascularization for ALI.

Methods: This is a retrospective observational study of patients undergoing revascularization for ALI between 2001 and 2018. Factors associated with outcome at 1 year in univariable analysis (p < 0.1) were chosen for multi-variable analysis and expressed in Odds Ratios (OR) with 95% confidence intervals (CI).

Results: The median age for women (n = 394) was 75 years and men (n = 449) was 70 years (p < 0.001). The frequency of fasciotomy was 10.0% (84/843). The median in-hospital stay was 28 vs. 6 days for patients undergoing fasciotomy and not, respectively (p < 0.001). In adjusted analysis, renal insufficiency (OR 1.77, 95% CI 1.04–3.01), motor deficit (OR 4.40, 95% CI 2.45–7.92), popliteal artery aneurysm thromboembolism (OR 2.26, 95% CI 1.06–4.80), and open vascular surgery (OR 3.43, 95% CI 1.97–5.98) were associated with an increased risk of fasciotomy. Female patients (OR 0.49, 95% CI 0.28–0.84) and anemia (OR 0.52, 95% CI 0.28–0.84) had a lower risk. The major amputation/mortality rate at 1-year was 27.7%; fasciotomy (OR 1.94, 95% CI 1.11–3.40), anemia (OR 1.84, 95% CI 1.24–2.73) and female gender (OR 1.44, 95% CI 1.00–2.08) were independently associated with an increased risk.

Conclusions: Female patients had lower rates of fasciotomies, but subsequent higher risk of major amputation/mortality, which may be attributed to inferior results of revascularization. Lower muscle mass and underdiagnosis of ACS could also explain the lower frequency of fasciotomy for female patients. Further studies are needed to better understand gender differences in presentation of ALI, revascularization results and diagnosis of ACS.

Utilizing Dynamic Phosphorous-31 Magnetic Resonance Spectroscopy for the Early Detection of Acute Compartment Syndrome: A Pilot Study on Rats

INTRODUCTION

Disasters, including terrorism and earthquakes, are significant threats to people and may lead to many people requiring rescue. The longer the rescue takes, the higher the chances of an individual contracting acute compartment syndrome (ACS). ACS is fatal if diagnosed too late, and early diagnosis and treatment are essential.

OBJECTIVE

To assess the ability of dynamic phosphorus magnetic resonance spectroscopy (31P-MRS) in the early detection of muscular damage in ACS.

MATERIALS AND METHODS

Six ACS model rats were used for serial 31P-MRS scanning (9.4 Tesla). Skeletal muscle metabolism, represented by the levels of phosphocreatine (PCr), inorganic phosphate (Pi), and adenosine triphosphate (ATP), was assessed. The PCr/(Pi + PCr) ratio, which decreases with ischemia, was compared with simultaneously sampled plasma creatine phosphokinase (CPK), a muscle damage marker.

RESULTS

The PCr/(Pi + PCr) ratio significantly decreased after inducing ischemia (from 0.86 ± 0.10 to 0.18 ± 0.06; p < 0.05), while CPK did not change significantly (from 89 ± 29.46 to 241.50 ± 113.28; p > 0.05). The intracellular and arterial pH index decreased over time, revealing significant differences at 120 min post-ischemia (from 7.09 ± 0.01 to 6.43 ± 0.13, and from 7.47 ± 0.03 to 7.39 ± 0.04, respectively). In the reperfusion state, the spectra and pH did not return to the original values.

CONCLUSIONS

The dynamic 31P-MRS technique can rapidly detect changes in muscle bioenergetics. This technique is a promising non-invasive method for determining early muscular damage in ACS.

Acute Lower Limb Ischemia in Patients Infected with COVID-19

Background

The aim of this study was to investigate the prevalence of acute lower limb ischemia (ALLI) among patients infected with COVID-19 and to review their characteristics and outcomes.

Methods

This study was performed at King Abdullah University Hospital (KAUH) in the north of Jordan. All patients with ALLI and COVID-19 infection, between November 1, 2020 and December 31, 2020, were retrospectively identified and reviewed.

Results

A total number of 1300 COVID-19 patients were admitted to KAUH during the period of the study. Seven patients (0.54%) had ALLI. Of them, 5 were males (71.4%) with a mean age of 68 ± 3 years and 2 were females (28.6%) with a mean age of 58 ± 7 years. Five patients (71.4%) were admitted as COVID-19 infection and developed ALLI during hospitalization, all of them were males, had COVID-19 related pneumonia, and died within 24 hours of ALLI diagnosis. While 2 patients were presented with ALLI and found to have positive COVID-19, all of them were females, underwent successful thrombo-embolectomy, and had no deaths, however, one of them had recurrent ALLI which resulted in below knee amputation.

Conclusion

The prevalence of ALLI in patients infected with COVID-19 was 0.54%. We observed that patients with COVID-19 related pneumonia who develop ALLI during hospitalization had a high mortality.

Electro-Acupuncture on ST36 and SP6 Acupoints Ameliorates Lung Injury via Sciatic Nerve in a Rat Model of Limb Ischemia-Reperfusion

Introduction

Electro-acupuncture (EA) can significantly improve inflammatory response, but the specific mechanism is not clear. Limb ischemia-reperfusion (I/R) first produces inflammatory reactions in the lungs. In this study, EA on Zusanli (ST36) and Sanyinjiao (SP6) were used to explore the mechanism of improving tissue inflammation by sciatic nerve disconnection.

Material and Methods

A total of 56 male Sprague-Dawley rats were randomly divided into sham group, model group, EA group, SEA group, SNC+EA group, TNC+EA group and PNC+EA group. The sham groups were not given any treatment. Rats in the model group were treated with limb I/R without acupuncture intervention. In the EA group, ST36 and SP6 were given EA treatment for 30min before modeling. No electric current was given in the SEA group, and other operations were the same as those in the EA group. The SNC+EA group, TNC+EA group and PNC+EA group were respectively given sciatic nerve, tibial nerve or peroneal nerve amputation 72h before modeling, and the others were the same as the model group.

Results

Compared with the sham group, PaO2 and a/A ratios decreased significantly in the model group (P <0.05), while PA-aO2, RI, the ratio of wet to dry, lung injury value and inflammatory factor TNF-α, IL-1, IL-6, and MPO increased significantly (P <0.05). Compared with the model group, PaO2, a/A ratios increased significantly in the EA group (P <0.05), while PA-aO2, RI, the ratio of wet to dry lung, lung injury value, and TNF-α, IL-1, IL-6, and MPO decreased significantly (P <0.05). After transection of the sciatic nerve, the protective effect of EA disappeared. However, when the peroneal or tibial nerve was severed, EA continued to maintain the protective effect.

Conclusion

EA on ST36 and SP6 can alleviate lung injury caused by limb I/R through the sciatic nerve.

Outcome of catheter directed thrombolysis for popliteal or infrapopliteal acute arterial occlusion

Management of acute limb ischemia (ALI) due to occlusions in popliteal and infrapopliteal arteries remains a challenge. Open surgical methods and even the novel percutaneous mechanical thrombectomy devices have not shown satisfactory results in these small arteries. The aim of this prospective study was to assess the safety and efficacy of catheter-directed thrombolysis (CDT) in this type of ALI with distal occlusion. Between April 2017 and June 2019, 22 patients with ALI secondary to popliteal or infrapopliteal occlusion were enrolled in the study. Patients with thrombosis, embolism, and thrombosed bypass graft were included; all belong to category I or IIa of Rutherford's classification. Technical success, limb salvage, complications, and mortality were evaluated at short- and long-term follow-up. Technical success was achieved in 81.8%, while 36.4% of patients needed additional balloon angioplasty, major amputation in 13.6%, minor bleeding in 18.2%, and no major hemorrhage. Limb salvage at 30 days and 1 year was 86.4% and 72.7%, respectively. At 1 year, primary patency was 63.6% and mortality was 9.1%. Catheter directed thrombolysis is a safe and highly effective treatment modality for popliteal or infrapopliteal acute limb ischemia unless contraindicated.

Blue toe syndrome caused by emboli from anomalous left atrial septal pouch thrombus: a case report

Background

Left atrial septal pouches (LASPs) are a relatively newly described but common anatomical cardiac variant thought to be associated with atrial fibrillation (AF) and cardio-embolic stroke. Blue toe syndrome (BTS) describes ischemic changes in the toes due to microembolisation of the digital arteries. Establishing the etiology of BTS is vital so that the underlying cause can be treated. Here we describe the first case of BTS arising due to emboli from LASP thrombus arising on a background of new-onset AF.

Case presentation

A 65-year-old man presented with a two-day history of progressive painful swelling and bluish-purple discoloration of the second and fourth toes of his left foot and new-onset AF. Tests for hypercoagulability disorders were negative. Duplex ultrasound and CT angiography excluded deep venous thrombosis and an absence of embolus, thrombus, or occlusion in the arterial tree in the lower extremities bilaterally, so BTS was diagnosed. While transthoracic echocardiography and chest CT initially showed no cardiac abnormalities or mural thrombus, subsequent transesophageal echocardiography revealed a LASP with an associated pedunculated thrombus. The affected toes were amputated due to wet gangrene, but the patient recovered well with thrombus resolution after anticoagulation.

Conclusion

The presence of a LASP in the absence of any other identifiable cause of BTS should trigger careful investigation of the interatrial septum, preferably using a multimodality imaging approach. The possibility that LASPs may not merely be an innocent bystander but a causative mechanism for peripheral ischemia must be considered.

Acute Lower Limb Ischemia-Etiology, Pathology, and Management

Acute limb ischemia (ALI) is a vascular emergency associated with a high risk for limb loss and death. Most cases result from in situ thrombosis in patients with preexisting peripheral arterial disease or those who have undergone vascular procedures including stenting and bypass grafts. The other common source is cardioembolic. The incidence has decreased in recent times due to better anticoagulation strategies. Patients with suspected ALI should be evaluated promptly by a vascular specialist and consideration should be given for transfer to a higher level of care if such expertise is not available locally. Initial assessment should focus on staging severity of ischemic injury and potential for limb salvage. Neurological deficits can occur early and are an important poor prognostic sign. Duplex ultrasound and computed tomography angiography help plan intervention in patients with a still-viable limb and prompt catheter-based angiography is mandated in patients with an immediately threatened limb. Further investigations need to be pursued to differentiate embolic from thrombotic cause for acute occlusion as this can change management. Options include intravascular interventions, surgical bypass, or a hybrid approach. In this article, the authors discuss the common etiologies, clinical evaluation, and management of patients presenting with acute limb ischemia.

Contemporary Management of Acute Lower Limb Ischemia: Determinants of Treatment Choice

The role of endovascular procedures in the treatment of acute lower limb ischemia (ALI) is expanding. For treatment, the choice between surgical or endovascular is still debated. The aim of this study was to identify factors that determine the selection of treatment. This study included 307 ALI patients (209 with thrombosis). Patient details, factors affecting the procedure choice, and outcomes were analyzed. The majority of patients were operated on (52.4%). Surgery was more frequent in embolic patients with embolus (odds ratio (OR) 33.85; 95% confidence interval (CI) 6.22–184.19, p < 0.0001), severe ischemia (OR 1.79; 95% CI 1.2–2.66, p = 0.0041), and active cancer (OR 4.99; 95% CI 1.26–19.72, p = 0.02). Tibial arteries involvement was negatively related to surgery (OR 0.25; 95% CI 0.06–0.95, p = 0.04). The complications and amputation rates were comparable. Reinterventions were more common in the endovascular group (19 (20.2%) vs. 17 (8.9%), p = 0.007). The six-month mortality was higher in the operated patients (12.6% vs. 3.2%, respectively, p = 0.001). The determinants of the treatment path are ischemia severity, concurrent cancer, embolus, and peripheral lesion location. Modification of the Rutherford acute lower limb ischemia classification is required to improve the decision-making in patients with profound ischemia.

Feasibility of MRI based oxygenation imaging for the assessment of acute limb ischemia

Background

Acute limb ischemia (ALI) can lead to death and amputation. Evaluating the severity of ischemia is important but difficult, through current methods of examination. The purpose of this research was to demonstrate the feasibility of magnetic resonance imaging (MRI) susceptibility-based imaging techniques for use in assessing muscle oxygenation alterations in ALI.

Methods

ALI animal models were established in 11 rabbits. Their left iliac arteries were embolized by microspheres. MRI scans were conducted 24 hours before (Pre) and 1 hour (Post 1) and 3 hours (Post 2) after the procedure. A susceptibility model was used to calculate skeletal muscle oxygenation extraction fraction (SMOEF) and relaxation rate (R2’). T2 weighted (T2w) imaging and diffusion-weighted (DW) imaging were performed.

Results

The average calf muscle SMOEF in the embolized hindlimbs increased from 0.43±0.02 (Pre) to 0.48±0.02 (Post 1) and 0.50±0.02 (Post 2), both P<0.05. The R2’ value increased from 13.01±2.31 s⁻¹ (Pre) to 16.78±2.28 s⁻¹ (Post 1) and 17.90±3.29 s⁻¹ (Post 2), both P<0.05. No significant changes of SMOEF and R2’ were found after embolization in the contralateral hindlimbs. Apparent diffusion coefficient (ADC) values derived from DW imaging remained unchanged at different stages compared to before the procedures (all P>0.05). No abnormal signals were observed in the anatomical T2w images at Post 1 and Post 2.

Conclusions

This study demonstrates the feasibility of using SMOEF for the assessment of oxygenation alterations in ALI models. SMOEF is more sensitive than T2w and DW imaging in detecting acute muscle ischemia at an early stage.