Characteristics of Peripheral Microembolization During Iliac Stenting: Doppler Ultrasound Monitoring

Distal embolization during percutaneous revascularization of the lower extremity arteries

Summary: Background: Percutaneous endovascular therapy is nowadays the leading treatment option for patients with symptomatic peripheral arterial disease, but it can be complicated with distal embolization (DE). Patients and methods: We retrospectively analyzed 2054 endovascular revascularization interventions performed in patients with disabling claudication or chronic critical limb ischemia in the Catheterisation Laboratory of the Department of Vascular Diseases, University Medical Centre Ljubljana between January 2014 and December 2018. Lesions were treated by balloon angioplasty and/or stent implantation, without atherectomy. Results: The overall incidence of DE was 0.9%. DE was more frequent in females than males (1.6% vs 0.5%, p = 0.011), in the absence of antiplatelet treatment prior to intervention compared to previous antiplatelet treatment (2.1% vs 0.6%, p = 0.005) and in femoropopliteal stenting compared to angioplasty without stenting (2.2% vs 0.8%, p = 0.037). DE was successfully managed with percutaneous aspiration, in combination with angioplasty when necessary, in 84% of cases. In remaining 16% of patients, DE was managed with surgical thromboembolectomy. Conclusions: The incidence of DE during endovascular revascularization of chronic atherosclerotic lesions in lower limb arteries without use of atherectomy was low. DE was more frequent in women, in patients without prior antiplatelet treatment and in femoropopliteal stenting. The majority of DE was successfully managed percutaneously.

Successful Treatment of Acute Limb Ischemia Secondary to Iatrogenic Distal Embolization Using Catheter Directed Aspiration Thrombectomy

Objective: Acute limb ischemia (ALI) due to thromboembolism is a limb- and life-threatening condition regularly encountered by vascular surgeons. Iatrogenic distal embolization is occasionally seen as a complication of various endovascular procedures. We present a series of four patients who developed ALI due to arterial embolization during cardiovascular procedures that were successfully treated via catheter directed aspiration embolectomy. Methods: Retrospective review of demographics, risk factors, and procedural outcomes was completed for 4 patients who presented with ALI due to distal embolization following cardiovascular procedures. All patients were successfully treated with catheter directed aspiration embolectomy using the Penumbra Indigo System (Penumbra Inc., Alameda, California). All patients had high-quality angiography demonstrating successful embolectomy and end-procedure patency. Results: Three patients presented with Rutherford 2A and one with Rutherford 2B ALI secondary to intraoperative distal embolization. Three patients presented with ALI secondary to distal embolization during peripheral vascular interventions, and one following emergent intra-aortic balloon pump (IABP) placement for myocardial infarction. All emboli were located in the infra-inguinal vasculature. Median post-operative ABIs were 0.94 (n = 4). Median length of stay was 2 days. There were no mortalities and no need for adjunctive fasciotomy, amputation, or bypass for limb salvage. All patients improved clinically after intervention, and returned to their reported pre-hospitalization functional status. Conclusion: All procedures achieved technical success with catheter-directed aspiration thrombectomy with or without adjunctive lysis. Catheter-directed aspiration embolectomy with the Penumbra Indigo System for ALI following an iatrogenic embolic event is a safe, less-invasive treatment option. The use of this technology may reduce the need for traditional open thrombectomy or thrombolytic therapy to address ALI.

The usefulness of Duplex Doppler ultrasound in the angiological and dermatological diagnosis of patients with blue toe syndrome

Introduction

Peripheral microembolism is one of the most frequent causes of acute limb ischemia. In order to effectively prevent relapses it is essential to localize and eliminate the source of embolism.

Aim

To evaluate the role of Duplex Doppler ultrasound examination in identifying the causes of blue toe syndrome (BTS).

Material and methods

The group of 165 patients with clinical symptoms of BTS on their upper limbs (n = 16) and lower limbs (n = 149) was investigated. They all underwent Duplex Doppler ultrasound of the major arteries of the extremities, where ischemic changes occurred.

Results

Morphological and functional changes which might be potential sources of microembolism were identified in 146 patients. These changes included significant short-length stenoses or unstable atherosclerotic plaque (n = 73), true aneurysms (n = 42) and pseudoaneurysms (n = 17). In 11 cases, pathology of vascular prostheses in the form of anastomotic aneurysms, infection and residual thrombi after fibrinolysis was detected. In all cases, Duplex diagnosis was confirmed by other imaging and intraoperative tests.

Conclusions

Duplex Doppler ultrasound of the arteries in the affected limb with a full length view should be the first-line examination in diagnosing patients with BTS. In the absence of hemodynamic blood flow disturbances in the major arteries in patients with symptoms of BTS, it is advisable to start haematological tests to identify/exclude congenital or acquired thrombophilia.

Distal macro- and microembolization during subintimal recanalization of femoropopliteal chronic total occlusions

PURPOSE

To investigate the phenomenon of distal embolization during subintimal angioplasty with or without stenting of femoropopliteal chronic total occlusions (CTOs).

METHODS

This prospective study included 40 consecutive patients (35 men; mean age 65.4±9.3 years) who underwent subintimal angioplasty alone (n=14) or with stenting (n=26) of CTOs in the femoropopliteal segment. A Spider protection filter was used to capture any possible macro- or microemboli generated during balloon inflation/stenting. Arterial outflow was angiographically checked during each consecutive procedural step. All filters were examined on site for macroscopic material, while the first 20 filters underwent further histopathological qualitative and semiquantitative analysis using a 0+ to 3+ score.

RESULTS

There was no angiographically or clinically evident distal embolization. Macroscopic particulate debris was not detected in any filter. Histopathology confirmed the absence of macroemboli but revealed microembolic material (diameter <100 μm) in all filters (20/20). The mean number of particles detected was 9.4±4.5 (range 5-17). Histopathological findings included fibrin conglomerates (20/20), trapped erythrocytes (19/20), inflammatory cells (16/20), calcification minerals (6/20), extracellular matrix (6/20), cholesterol clefts (6/20), and endothelial cells (6/20). Captured material was classified as fresh and old thrombus in 7/20 and 4/20 cases, respectively. Semiquantitative analysis demonstrated that the collected microparticles consisted primarily of fibrin conglomerates (median score 2+), trapped erythrocytes (median score 1+), and inflammatory cells (median score 1+).

CONCLUSION

Macroscopically evident emboli were not detected following subintimal angioplasty or stenting of femoropopliteal CTOs. Microscopic debris was present in all filters. The clinical significance of the phenomenon remains to be determined.

Embolic capture angioplasty of lower extremity lesion following distal embolization

Peripheral embolization is a known complication of peripheral artery interventions. It can lead to occlusion of distal vessels leading to significant lower extremity ischemia and complications. Peripheral artery interventions involving chronic total occlusions have been shown to have higher rates of complications including distal embolization. Although distal embolic protection strategies are available, they are seldom utilized during lower extremity interventions, especially during treatment of totally occluded vessels. Proteus embolic capture angioplasty balloon may provide operators with the option of balloon dilation of stenotic lesion in the peripheral arterial bed, along with embolic capture. We report a case where use of this novel device helped in achieving a successful angioplasty outcome along with evacuation of distal embolus and restoration of antegrade flow.

Doppler ultrasonography-aided early diagnosis of venous thromboembolism after total knee arthroplasty

OBJECTIVES

Postoperative deep venous thrombosis (DVT) is usually asymptomatic but can result in a fatal pulmonary embolism (PE). To assess the ability of transcranial Doppler (TCD) ultrasound apparatus to detect venous emboli in patients who had undergone total knee arthroplasty (TKA).

METHODS

Forty-eight patients undergoing TKA were examined postoperatively by using compression ultrasonography, computed tomographic angiography, and TCD ultrasonography that detected high-intensity transient signals (HITS) in femoral veins. An original scoring system based on both the number of HITS and the locations of DVT was tested for its accuracy in predicting PE development.

RESULTS

Twenty-three of the 48 patients had DVT postoperatively, and 8 had an asymptomatic PE. The sensitivity and specificity of the HITS assessment alone in identifying PE development were 75% and 92.5%, respectively. The scoring system, however, had a sensitivity of 100% and a specificity of 85% and the area under the receiver operating characteristic (ROC) curve (AUC) was 0.96.

CONCLUSIONS

Application of a scoring system based on the detection of both DVT and HITS may be an effective and efficient method of screening for PE after knee arthroplasty.

Detection of venous emboli using Doppler ultrasound

OBJECTIVES

To detect emboli in the venous system using a Doppler ultrasound device with embolism detecting software.

METHODS

Pulmonary embolism (PE) was induced by injecting thrombus through the iliac vein of castrated swine under general anaesthesia. Data recorded from the Doppler system were analysed for high intensity transient signals (HITS) using receiver operating characteristic curves. Four different thrombi (5 or 10mm long and 3 or 5mm in diameter) were then injected to assess the quantitative analysis.

RESULTS

Thrombus could be detected in the venous system by the Doppler ultrasound device with an embolism detecting function. Appropriate confidence level was 60%. If thrombus were assumed to travel at the maximum flow rate (30 cm/s) in the inferior vena cava, the estimated embolism size was 10.4 S.D. 2.8mm for 3mm and 10.8 S.D. 4.9 mm for 5mm, both of which were close to 10mm.

CONCLUSION

Thrombi could be detected as high intensity transient signals in the venous system. The appropriate confidence level was 60%. The size of emboli can be estimated if they are more than 3mm in diameter when the venous flow rate is 30 cm/s or less. Our results suggest that it may be possible to detect emboli in the subclavian vein, axillary vein or inferior vena cava in clinical cases.