Acute femoropopliteal artery stent obstruction

Abstracts

Femoropopliteal stent obstruction may be responsible for acute lower limb ischemia. Fibrinolytic treatment may not be the best therapeutic approach in this group of patients. We report a clinical case in which stent fragmentation and endarterectomy enabled femoropopliteal below knee bypass and limb revascularization.

ischemia; fibrinolysis; endarterectomy; graft occlusion

A oclusão aguda de stent fêmoro-poplíteo pode ser causa de isquemia crítica dos membros inferiores. A terapia fibrinolítica pode não ser a forma de tratamento mais indicada para o grupo de pacientes com esse quadro clínico. Neste artigo, apresentamos um caso em que a retirada de um fragmento de stent por endarterectomia tornou possível a revascularização do membro.

isquemia; extremidade inferior; fibrinólise; endarterectomia; oclusão de enxerto vascular

CASE REPORT

Acute femoropopliteal artery stent obstruction

Fabio Henrique Rossi^I; Milton Kiyonory Uehara^II, Juliana Chen^II; Thiago Emilio Burza Maia^II; Eduardo Mulinari Darold^II; Andréia Silveira Martins^II; Nilo Mitsuro Izukawa^III; Akash Kuzhiparambil Prakasan^II

^ICirurgião vascular assistente, Instituto Dante Pazzanese de Cardiologia (IDPC), São Paulo, SP, Brazil. Cirurgião vascular e endovascular responsável, Hospital Adventista de São Paulo, São Paulo, SP, Brazil, e Hospital São Caetano, São Caetano do Sul, SP, Brazil. Doutor em Ciências (Clínica Cirúrgica), Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil. Especialista em Cirurgia Vascular, SBACV

^IISetor de Cirurgia Vascular Periférica, IDPC, São Paulo, SP, Brazil

^IIIChefe, IDPC, São Paulo, SP, Brazil

Correspondence

ABSTRACT

Femoropopliteal stent obstruction may be responsible for acute lower limb ischemia. Fibrinolytic treatment may not be the best therapeutic approach in this group of patients. We report a clinical case in which removal of a stent fragment with endarterectomy enabled limb revascularization.

Keywords: ischemia, lower limb, fibrinolysis, endarterectomy, vascular graft occlusion.

Introduction

Acute arterial obstruction of lower limbs may be an important factor for cardiovascular morbidity and mortality. There are 17 new cases for every 100,000 inhabitants per year.¹ Its etiology is associated with embolization and arterial thrombosis. With the increased number of endovascular procedures being performed to treat this group of patients, intimal hyperplasia should be considered in the differential diagnosis, because it may be the cause for stent thrombosis. The use of thrombolytics may not be the best therapeutic approach in these cases.

Case report

A 70-year old male patient had a history of angioplasty with stent placement in left popliteal artery performed approximately 1 year before. He was admitted to the emergency room and presented with disabling claudication in the left lower limb which had started on the previous day. Personal history: arterial hypertension – it was under control at admission – and smoking. On physical examination, the femoral pulse was the only palpable pulse in left lower limb; all pulses were palpable in the contralateral limb. Other findings were: coldness starting at the mid-third of the left lower limb; reduced plantar perfusion; mild paresthesia of the forefoot; and absence of arterial flow in tibial arteries as assessed by a portable Doppler ultrasound device. The acute arterial obstruction was classified as Rutherford grade 2a. Initially, the patient underwent limb warming and full intravenous heparinization. Digital subtraction angiography revealed patency of common, superficial and deep femoral arteries, with diffuse atheromatosis (not obstructing the flow), and arterial obstruction at the level of the stent (popliteal artery), with refilling of the infragenicular popliteal artery, tibial and fibular arteries with diffuse atheromatosis (Figure 1).

Chemical thrombolysis was performed with local infusion of streptokinase through a multiperforated catheter inserted with the crossover technique (contralateral retrograde femoral puncture and use of a pigtail catheter). The loading dosage was 20,000 UI in 20 minutes; afterward, continuous infusion with an infusion pump at 5,000 UI/h was administered. Systemic heparinization was maintained through intravenous infusion of unfractionated heparin with infusion pump. Anticoagulation levels were monitored with activated partial thromboplastin time (aPTT) values. Control arteriography was performed every 6 hours. After 11 hours of infusion, decreased hemoglobin, hematocrit and fibrinogen levels were revealed, without hypotension symptoms. At arteriography, performed through the introducer sheath, the stent remained occluded (Figure 2).

There were no observable clinical changes in the ischemic limb during infusion of fibrinolytic agents. The patient underwent surgical exploration. The arteriotomy performed on the infragenicular popliteal artery showed that stent meshes had migrated to the site chosen for distal anastomosis of the graft. A macroscopic occlusion of the stent lumen with a fibrous and whitish tissue was observed, suggesting occlusion due to intimal hyperplasia (later confirmed by histological examination). After the distal end of the stent was cut and the fibrous mass was removed with open endarterectomy, distal anastomosis and infragenicular femoropopliteal bypass with reverse great saphenous vein were performed (Figure 3).

In the immediate postoperative period, the patient progressed with improved perfusion of the limb and presence of distal pulses; he was discharged on the 3rd postoperative day with no complications and with improved symptoms.

Discussion

In the case reported here, stent occlusion occurred 1 year after the stent placement, period during which intimal hyperplasia is the main cause for occlusion.^1,2 Experimental studies showed that it is due to local hemodynamic disorders – shear stress, compliance mismatches, interactions of blood components (platelets, lymphocytes) with the endothelium. Endothelial injury is the main factor for the development of intimal hyperplasia. It involves the formation of smooth muscle cells and an extracellular matrix of loose connective tissue.³

In femoropopliteal angioplasty followed by stent placement, local anatomical and mechanical characteristics seem to be a predisposing factor for intimal hyperplasia,⁴ which is the main cause for the low patency rates observed.^5,6

The need for early identification and treatment of obstructive lesions that may place patency at risk after conventional surgical⁷ or endovascular⁸ revascularization has already been demonstrated. The treatment of these lesions prolongs graft patency and reduces morbidity and mortality rates.

In the case of an acute thrombosis, fibrinolytic treatment may dissolve the recent thrombus and reveal the obstructive lesion. It may enable the endovascular treatment of the lesion or reduce the extent of the surgery to be performed. This consideration is real when results obtained in the aortoiliac segment are observed.⁹ However, studies that support the use of this approach in the femoropopliteal segment were not found.

References to the removal of a stent fragment followed by endarterectomy so as to enable anastomosis in the segment (as performed in our patient) were not found either. The distal end of the stent was in the infragenicular popliteal artery. If the surgical removal of the fragment had not been possible, anastomosis would have had to be performed in one of the leg arteries, increasing surgical morbidity and potentially decreasing its patency.

In the case of acute artery obstruction in patients who underwent angioplasty and stent placement in the femoropopliteal segment, it was observed that fibrinolytic treatment may not be the best approach and it should not defer the surgical treatment for artery reperfusion of the ischemic limb. It is known that, after stent placement, technical failures, distal bed resistance and hypercoagulability may cause early failure of the angioplasty. Furthermore, it is known that the main reason for obstruction during the first year of clinical follow-up is intimal hyperplasia. Within this period, in which our patient developed ischemic symptoms, thrombolysis may not be the best therapeutic option. Furthermore, it should be considered that, unlike the aortoiliac segment, the mechanical characteristics and the extent of the obstruction observed in the femoropopliteal segment may not recommend the use of endovascular techniques.

We conclude that surgical endarterectomy with removal of a stent fragment is a feasible therapeutic option and it may be used in patients with acute obstruction of a femoropopliteal stent, that is, when the presence of a stent may make graft anastomosis difficult to be performed.

References

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• 9. Mussa FF, Peden EK, Zhou W, Lin PH, Lumsden AB, Bush RL. Iliac vein stenting for chronic venous insufficiency. Tex Heart Inst J. 2007;34:60-6.

Publication Dates

• Publication in this collection
  04 Sept 2009
• Date of issue
  Sept 2009

History

• Received
  08 Sept 2008