Abstract
Acute limb ischemia due to bypass thrombotic occlusion may occur in patients with poor collateral circulation. It constitutes a medical emergency with increased morbidity, mortality and risk for limb amputation. Although the management of acute limb ischemia due to native artery occlusion is well studied, the optimal approach of acute bypass graft failure resulting in acute limb ischemia is uncertain. We present a case of acute limb ischemia in a patient with femoro-femoral and femoro-popliteal graft who presented with acute limb ischemia due to acute thrombotic occlusion of his femoro-popliteal graft. The patient was successfully managed with ultrasound-enhanced catheter-directed thrombolysis using the EkoSonic® endovascular system with excellent clinical and angiographic results. To our knowledge this is the first published report of the use of the EkoSonic® system for this indication.
1
Surgery for complex multi-level peripheral arterial disease
According to the TASC-II classification, multi-level peripheral arterial disease with the presence of long occlusions is categorized in the “class D” sub-group and a surgical approach is preferred as an initial approach in symptomatic patients . The extra-anatomical crossover femoro-femoral bypass graft (CFFBG) procedure was first described in 1952. It is commonly performed in high-risk patients with patent unilateral iliac arteries due its ease for the patient as it can be done under local anesthesia and its patency rates are comparable to aorto-femoral bypass in selected patients . The primary, secondary patency rates and limb salvage rates at 10 years are estimated to be 48.1%, 63.2% and 80.1% respectively . Femoro-popliteal grafting is one of the most common surgical procedures for limb salvage but its 5-year patency rates vary from 40 to 80% depending on the location, material and acuity of the initial surgery . Bypass surgery is preferred in patients with more complex PAD lesions. However, inflow and outflow patency, graft material, perianastomotic stenosis, vein graft stricture, focal vein stenosis, valvulotome injury, kinking of the graft, retained valve leaflet, intimal flap and residual arteriovenous fistula have all been correlated with early graft failure. Moreover, patients aged < 60 years, African American race, nondiabetics, patients with lower hematocrit and patients with tibial vessel bypass appear to have higher risk for early graft failure .
2
Options for occluded by-pass grafts
Occlusion of a by-pass graft often results in recurrence of symptoms ranging from intermittent claudication to acute or critical limb ischemia depending on the acuity of occlusion and the presence of collateral circulation. Multiple approaches have been used for the have been used for the treatment of occluded by-pass grafts including endovascular mechanical and chemical thrombolysis or surgical thrombectomy .
2
Options for occluded by-pass grafts
Occlusion of a by-pass graft often results in recurrence of symptoms ranging from intermittent claudication to acute or critical limb ischemia depending on the acuity of occlusion and the presence of collateral circulation. Multiple approaches have been used for the have been used for the treatment of occluded by-pass grafts including endovascular mechanical and chemical thrombolysis or surgical thrombectomy .
3
Development of Ultrasound – Accelerated Catheter – Directed Thrombolysis
Catheter-directed thrombolysis (CDT) allows the delivery of high concentration therapeutic agents directly to the affected vascular segments. High frequency ultrasound is thought to increase the permeability of the thrombolytic agent into the thrombus through the fibrin strands resulting in increased effectiveness . Ultrasound accelerated catheter-directed thrombolysis through the EkoSonic® Endovascular System (EKOS Corporation, Bothell, WA, USA) has been successfully used for the management of deep venous thrombosis (DVT) and pulmonary embolism (PE) ( Fig. 1 ). Furthermore, it has demonstrated promising results in the management of acute thromboembolic arterial disease and a randomized trial comparing it to the standard thrombolysis (DUET trial) is underway . Its published use for the management for the management of acute lower extremity by-pass occlusion is limited with only one 10-patient case series published study available from Germany .
The EkoSonic® endovascular system consists of a 0.035-inch guidewire compatible catheter which incorporates small ultrasound transmitters for the delivery of ultrasound waves ( Fig. 2 ). The use of ultrasound in endovascular thrombus has been proven to enhance enzyme-mediated thrombolysis by application of constant operating parameters (COP), reducing the amount of thrombolytics (volume and time) and achieving better patency rates .
4
Case presentation
A 57-year-old patient with a history of coronary artery disease (CAD) post acute myocardial infarction (MI) and stent thrombosis within a week after primary percutaneous coronary intervention (PCI), 3-vessel CABG shortly thereafter, hypertension, dyslipidemia, remote history of tobacco abuse and history of peripheral arterial disease (PAD) presented to the emergency with acute left leg pain. He had a known occluded left common iliac (CIA), external iliac (EIA) and superficial femoral arteries (SFA) post right-to-left CFFBG and left femoro-popliteal graft (FPG) 3 years ago. In the emergency room his left limb appeared to be pale, cold, paresthetic and paretic with absent femoral, popliteal, posterior tibial and dorsalis pedis pulses. With persistent resting pain, decreased sensory and motor function he was diagnosed with IIB acute left lower limb ischemia (ALI) and we were consulted after administration of 325 mg of aspirin and initiation of unfractionated heparin drip. An arterial venous Doppler showed absent arterial and audible venous Doppler signals. After discussion with our vascular surgery consultants the patient was transferred emergently to the cath lab with type IIB threatened limb ischemia .
A 5 F sheath was placed in the right radial artery and a 130 cm Soft-Vu braided Bernstein catheter (Angiodynamics, Latham, NY, USA) was used for a selective right iliac angiogram and bilateral run-off ( Fig. 3 ). The left iliac arteries were known to be occluded. The right iliac and femoral arteries showed absence of atherosclerosis. The femoro-femoral bypass graft was patent with a flush occlusion of the left common femoral artery, which appeared to be at the site of anastomosis with the femoro-popliteal graft.
