Controlled Reperfusion Versus Conventional Treatment of the Acutely Ischemic Limb

DNase I and Sivelestat Ameliorate Experimental Hindlimb Ischemia-Reperfusion Injury by Eliminating Neutrophil Extracellular Traps

Purpose

Neutrophil extracellular traps (NETs) play an important role in ischemia-reperfusion injury (IRI) of the hindlimb. The aim of this study was to investigate the effect of recombinant DNase I and sivelestat in eliminating NETs and their effects on IRI limbs.

Patients and Methods

An air pump was used to apply a pressure of 300 mmHg to the root of the right hindlimb of the rat for 2 h and then deflated to replicate the IRI model. The formation of NETs was determined by the detection of myeloperoxidase (MPO), neutrophil elastase (NE), and histone H3 in the skeletal muscles of the hindlimbs. Animals were administered 2.5 mg/kg bw/d DNase I, 15 or 60 mg/kg bw/d sivelestat by injection into the tail vein or intramuscularly into the ischemic area for 7d. Elimination of NETs, hindlimb perfusion, muscle fibrosis, angiogenesis and motor function were assessed.

Results

DNase I reduced NETs, attenuated muscle fibrosis, promoted angiogenesis in IRI area and improved limb motor function. Local administration of DNase I improved hindlimb perfusion more than intravenous administration. Sivelestat at a dose of 15 mg/kg bw/d increased perfusion, counteracted skeletal muscle fibrosis, promoted angiogenesis and enhanced motor function. However, sivelestat at a dosage of 60 mg/kg bw/d had an adverse effect on tissue repair, especially when injected locally.

Conclusion

Both DNase I and moderate doses of sivelestat can eliminate IRI-derived NETs. They improve hindlimb function by improving perfusion and angiogenesis, preventing muscle fibrosis. Appropriate administration mode and dosage is the key to prevent IRI by elimination of NETs. DNase I is more valid when administered topically and sivelestat is more effective when administered intravenously. These results will provide a better strategy for the treatment of IRI in clinical.

Mechanisms and Interventions on Acute Lower Limb Ischemia/Reperfusion Injury: A Review and Insights from Cell to Clinical Investigations

AIM

This review aims to highlight mechanistic insights on skeletal muscle ischemia/reperfusion injury (IRI), a potentially life-threatening complication after acute lower limb ischemia. Lower limb IRI produces a wide spectrum of manifestations, ranging from local skeletal muscle necrosis to multi-organ failure. There is increasing evidence from both in vitro and in vivo reports to demonstrate several promising interventions that have successfully reduced IRI in skeletal muscle ischemic models. However, clinical studies to confirm their benefits are still lacking.

METHOD

We conducted a comprehensive search of English literature listed in the PubMed database (All related published articles shown in PubMed until September 2020 have been included in this review), using the following keywords: acute limb ischemia, acute arterial occlusion, compartment syndrome, ischemic reperfusion injury, revascularization and hypoxic reoxygenation.

RESULT

58 articles pertinent to acute limb ischemia models were identified. The underlying mechanisms associated with IRI in skeletal muscle are due to excessive mitochondrial production of reactive oxygen species (ROS), cellular apoptosis and activation of inflammatory cascades. Several therapeutic interventions including both pharmacological and non-pharmacological treatments have been investigated and some showed promising results. These interventions include antioxidation, anti-inflammation, anti-hypertension, controlled-reperfusion and ischemic preconditioning. Further clinical studies are needed to warrant their use in a clinical setting for lower limb IRI treatment.

CONCLUSION

This review comprehensively summarizes the mechanisms underlying IRI in lower limb ischemia. The reports currently available regarding the potential therapeutic interventions against lower limb IRI from in vitro, in vivo and clinical studies are presented and discussed. These findings may provide mechanistic insights for devising the strategies to improve the clinical outcomes in IRI patients in the near future. Further clinical studies are needed to warrant their use in a clinical setting for lower limb IRI treatment.

Acute Aortic Occlusion and Its Sequelae: Metabolic, Pathologic Etiology, and Management

Acute occlusion of the abdominal aorta is a catastrophic occurrence that results in high risk of limb loss and death. The etiology has historically been either acute embolism obstructing the aortic bifurcation in 8% to 75% of patients, or thrombosis of existing aorta-iliac occlusive disease in 35% to 84% of patients. Other etiologies include thrombosis of either a previously placed endograft or aortic graft or acute dissection. The most common symptoms are severe pain in almost 100% of patients or lower extremity paralysis/paresis in up to 80% of patients. Evaluation in the past was by angiography, but presently, computed tomography angiography is the preferred imaging study. Treatment is dependent on the etiology and includes embolectomy, aorta femoral bypass, axillary femoral bypass, and endovascular techniques. The aim of intervention is to restore flow in the shortest time period. Mortality rates vary widely from 17% to 52%, amputation occurs in up to 30% of patients. Paraplegia can occur in 40% of patients, renal insufficiency in 40% to 70%, and visceral ischemia in 6% to 14%. Both mortality and morbidity are affected by the duration of ischemia and the local and systemic complications of reperfusion injury. Complications of acute aortic occlusion can be reduced by a more prompt diagnosis, rapid intervention, and a more rapid and complete reestablishment of perfusion.

Open or endovascular revascularization in the treatment of acute lower limb ischaemia

Background

Consensus is lacking regarding intervention for patients with acute lower limb ischaemia (ALI). The aim was to study amputation‐free survival in patients treated for ALI by either primary open or endovascular revascularization.

Methods

The Swedish Vascular Registry (Swedvasc) was combined with the Population Registry and National Patient Registry to determine follow‐up on mortality and amputation rates. Revascularization techniques were compared by propensity score matching 1 : 1.

Results

Of 9736 patients who underwent open surgery and 6493 who had endovascular treatment between 1994 and 2014, 3365 remained in each group after propensity score matching. Results are from the matched cohort only. Mean age of the patients was 74·7 years; 47·5 per cent were women and mean follow‐up was 4·3 years. At 30‐day follow‐up, the endovascular group had better patency (83·0 versus 78·6 per cent; P < 0·001). Amputation rates were similar at 30 days (7·0 per cent in the endovascular group versus 8·2 per cent in the open group; P = 0·113) and at 1 year (13·8 versus 14·8 per cent; P = 0·320). The mortality rate was lower after endovascular treatment, at 30 days (6·7 versus 11·1 per cent; P < 0·001) and after 1 year (20·2 versus 28·6 per cent; P < 0·001). Accordingly, endovascular treatment had better amputation‐free survival at 30 days (87·5 versus 82·1 per cent; P < 0·001) and 1 year (69·9 versus 61·1 per cent; P < 0·001). The number needed to treat to prevent one death within the first year was 12 with an endovascular compared with an open approach. Five years after surgery, endovascular treatment still had improved survival (HR 0·78, 99 per cent c.i. 0·70 to 0·86) but the difference between the treatment groups occurred mainly in the first year.

Conclusion

Primary endovascular treatment for ALI appeared to reduce mortality compared with open surgery, without any difference in the risk of amputation.

Endovascular may save lives