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New Technology for the Treatment of Peripheral Arterial and Venous Occlusions: Ultrasound Accelerated Thrombolysis
New Technology for the Treatment of Peripheral Arterial and Venous Occlusions: Ultrasound Accelerated Thrombolysis j Stephanie D. Crouch, RN; Deborah Hill, RN; and Donna Bridwell, RT (R) (VI) ABSTRACT: Peripheral arterial occlusion and deep venous thrombosis are common and serious conditions that can lead to pain, limb loss, or even death. As many patients with arterial and venous occlusions of the peripheral vasculature are cared for by radiology nurses, it is important to understand the risk factors, presentation, treatment options, and the new technology available to improve outcomes. In addition to pharmacotherapy and open surgery, many patients with these conditions are treated with endovascular interventions such as catheterdirected thrombolysis and percutaneous mechanical thrombectomy. A novel technique, ultrasound accelerated thrombolysis (USAT), has been developed to more rapidly and completely resolve thrombus, overcoming limitations associated with earlier treatment options. In an illustrative case study, early recanalization and complete thrombus resolution of extensive and potentially chronic thrombus in the lower extremity after only an overnight infusion demonstrate the effective and successful use of USAT. (J Radiol Nurs 2008;27:14-21.)
INTRODUCTION Occlusions of the peripheral arteries and veins are common and serious conditions that can lead to pain, limb loss, or even death. Although treatment ranges from pharmacotherapy to open surgery, many patients are also seen in the angiography suite to be treated with interventions such as catheter-directed thrombolysis (CDT), percutaneous mechanical thrombectomy (PMT) and a novel technique, ultrasound accelerated thrombolysis (USAT). When a stenosis is revealed, it
Stephanie D. Crouch, RN, Deborah Hill, RN, and Donna Bridwell RT (R) (VI), are with Interventional Radiology Department, St. Anthony’s Medical Center, at St. Louis, MO. The authors hold no financial interest in any product or manufacturer mentioned in the article. Corresponding author Stephanie D. Crouch, Interventional Radiology Department, St. Anthony’s Medical Center, 10010 Kennerly Road, St. Louis, MO 63128. E-mail: [email protected] 1546-0843/$34.00 Copyright Ó 2008 by the American Radiological Nurses Association. doi: 10.1016/j.jradnu.2007.12.002
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is resolved with a procedure such as angioplasty, stent implantation, or plaque excision. It is important for radiology nurses caring for patients being treated for arterial or venous occlusions to understand the risk factors, presentation, treatment options, and the new technology available to improve outcomes. Our case study illustrates the successful use of USAT in a patient with extensive and potentially chronic thrombus in the lower extremity. The patient presented with acute onset of right extremity pain and a history of vascular disease. After treatment with USAT, this patient experienced early recanalization and complete thrombus resolution of her occluded femoral-tibial peroneal bypass graft with only an overnight infusion. USAT unmasked an underlying lesion that was successfully treated with angioplasty and at 1 month, the patient continued to have pulses and had no leg pain. PERIPHERAL ARTERIAL DISEASE AND OCCLUSIONS Peripheral arterial disease (PAD) is a common condition whose symptoms affect approximately 10 million
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people in the United States. An additional 20 to 30 million Americans have asymptomatic PAD (Allaqaband, Solis, Kazemi, & Bajwa, 2006; Hirsch & Criqui, 2001). Patients affected with the disease have an increased risk of cardiovascular events and mortality. PAD is characterized by reduced blood flow in limb arteries, typically the legs, and is most frequently caused by atherosclerotic plaque buildup that causes narrowing of the arterial lumen. Narrow, diseased vessels are more prone to occlusion by an embolus, thrombus, or acute trauma. The prevalence of peripheral arterial occlusion (PAO) is estimated to be 14 out of 100,000 (Davies et al., 1997; Giannini & Balbarini, 2004). When clot blocks blood flow into the affected limb, the patient experiences pain, a cold, or blue leg and is at risk for amputation. Similar to coronary artery disease, key risk factors for PAD include tobacco use, diabetes mellitus, hypertension, high cholesterol, family history, obesity, dyslipidemia, and increasing age (Clagett et al., 2004; Sieggreen, 2006). PAD patients have a wide variety of presenting symptoms with a marked difference between chronic and acute onset. Patients with chronic disease often experience pain during walking, known as intermittent claudication. This is the most common symptom of lower extremity PAD, present in up to 20% of patients older than 75 years (Sieggreen, 2006). Approximately 25% of patients with intermittent claudication will deteriorate to more severe disease (Dormandy & Rutherford, 2000). More serious symptoms of chronic PAD include critical limb ischemia, characterized by rest pain and indicating that there is insufficient blood flow to sustain tissue. Often, this progresses to ischemic ulcers or gangrene. If blood flow is not reestablished, these conditions may lead to amputation, which becomes necessary in 1% to 3% of symptomatic patients (Dormandy & Rutherford, 2000). Acute onset of an arterial occlusion, as a first occurrence or in a patient with chronic disease, is most commonly caused by underlying atherosclerosis and the sudden loss of blood flow due to clot formation in a native artery or bypass. Due to the abrupt development of the occlusion, collateral blood supply is not well established resulting in ischemia. Patients with severe acute occlusion present with pain followed by paresthesia, motor dysfunction, and eventual tissue death (Ouriel, 2002). Acute limb ischemia threatens the viability of the extremity and is associated with a 1-year mortality rate of approximately 20% (Ouriel, 2002). Management of PAOs depends on many factors including extent and location of the disease, patient comorbidities, occlusion duration (e.g., acute or chronic), and type of occlusion (e.g., embolic or thrombotic). Initial treatment for PAD without limb ischemia includes
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exercise, risk factor modification, and pharmacotherapy to reduce symptoms and help control the disease. Risk factor modification includes smoking cessation to slow the progression of PAD and lower risk of cardiovascular events, as well as weight loss, blood pressure reduction, blood glucose control, and lipid modification to reduce cardiovascular morbidity and mortality (Sieggreen, 2006). Antiplatelet therapy with aspirin and clopidogrel is initiated to inhibit thrombus propagation (Allaqaband et al., 2006; Clagett et al., 2004; Ouriel, 2002). Medical therapy decreases the risk of associated cardiovascular events and lowers the risk of recurrent thrombosis (Clagett et al., 2004; Sieggreen, 2006). Patients with disabling claudication and profound limb ischemia require more aggressive treatment such as endovascular interventions or open surgery to restore blood flow quickly (Ouriel, 2002). Historically, open surgical techniques such as thromboembolectomy or bypass grafting have been the primary treatment for acute limb ischemia. However, patients with PAD tend to be medically compromised due to comorbid conditions such as coronary artery disease and cerebrovascular disease that associate open surgical procedures with a significant mortality rate (Ouriel, 2002; Ouriel, Veith, & Sasahara, 1998). In fact, due to related complications, surgical intervention for the treatment of acute limb ischemia is associated with a 30-day mortality rate of up to 25% (Ouriel et al., 1998). For this reason, less invasive interventional procedures such as CDT and PMT have become widely accepted alternatives to surgery. Although CDT has demonstrated comparable or favorable morbidity and mortality rates to open surgery, extended duration of thrombolytic infusion and large drug dosages required to achieve recanalization of the vessel may lead to serious hemorrhagic complications. PMT devices have demonstrated efficacy in rapidly macerating and extracting thrombus, but with limited effectiveness in older occlusions and increased potential for distal embolization and residual thrombus (Grimm, Jahnke, Muhle, Heller, & Mu¨ller-Hu¨lsbeck, 2003; Kalinowski & Wagner, 2003). For these reasons, PMT is generally used as an adjunct to CDT rather than as a stand-alone treatment. DEEP VENOUS THROMBOSIS Deep venous thrombosis (DVT), the most common manifestation of venous thromboembolism, occurs in as many as 250,000 Americans each year (Augustinos & Ouriel, 2004). DVT typically occurs in the deep veins of the lower extremities; however, upper extremities are involved in approximately 4% of cases (Elman & Kahn, 2006; Kommareddy, Zaroukian, & Hassouna, 2002). Patients with acute DVT typically present with
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symptoms that abate over time with the development of collateral pathways including limb edema, pain, and difficulty with walking. However, many patients continue to experience symptoms due to outflow obstruction, particularly during exercise (Augustinos & Ouriel, 2004). DVT is associated with disabling and potentially life-threatening acute and chronic complications. The most serious complication of DVT is pulmonary embolism, resulting in as many as 100,000 deaths annually in the United States (Haines, 2003). Other complications of DVT include recurrent thrombosis, which occurs in up to 10% of DVT patients within 3 years, and may cause symptoms and complications including pulmonary embolism (PE) (Augustinos & Ouriel, 2004). Postthrombotic syndrome (PTS), the most common DVT complication found in two thirds of patients with iliofemoral DVT, refers to chronic venous insufficiency resulting from valvular incompetence and venous obstruction (Augustinos & Ouriel, 2004; Laiho et al., 2004). Patients with PTS present with a wide spectrum of symptoms including limb edema, leg heaviness, claudication, hyperpigmentation and, in severe cases, ulceration (Augustinos & Ouriel, 2004; Semba, Razavi, Kee, Sze, & Dake, 2004). Virchow’s triad highlights the following causes of venous thrombosis: endothelial injury, blood flow abnormalities, and hypercoagulability. Specific risk factors for DVT include recent surgery, bed rest, orthopedic surgery, advanced age, cardiac disease, malignancy, immobilization, spinal injury, leg trauma, pregnancy, acquired and inherited hypercoagulable states, use of oral contraceptives, obesity, presence of intravenous access devices, and previous episodes of venous thrombosis (Sharafuddin et al., 2003). In younger women, the compression of the left iliac vein by the artery crossing over it, known as May-Thurner Syndrome, is a common contributing factor in DVT. Treatment for DVT ranges from anticoagulation therapy to surgical intervention. The goal of the treatment is to reduce symptom severity and prevent acute and late complications such as PE, recurrent thrombosis, and PTS. The standard of care for DVT is anticoagulation therapy with unfractionated or low-molecular-weight heparin followed by oral anticoagulants. Inferior vena cava filters are indicated to prevent PE in DVT patients who are contraindicated for anticoagulation therapy. Although anticoagulation prevents further thrombus formation, it does not dissolve the existing occlusion. This limitation results in a significant number of patients with residual thrombus that leads to low long-term patency rates (AbuRahma et al., 2001). Surgical thrombectomy provides rapid and complete removal of occlusive thrombus; however,
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this technique has been associated with a high-recurrence rate and significant mortality (Ouriel et al., 1998). For these reasons, surgical thrombectomy is typically reserved for patients contraindicated or refractory to other treatments. Interventional procedures for DVT including CDT and PMT attempt to resolve existing thrombus without the inherent risks of open surgery. CDT has become an accepted DVT treatment in select patients and has demonstrated efficacy in achieving complete and partial lysis. However, extended lysis times, over 48 hr in many cases, and the associated risk of hemorrhagic complications have prevented more widespread use of this technique in the treatment of DVT (Semba et al., 2004). PMT devices, designed to fragment and extract thrombus, are used as stand-alone therapy or as an adjunct to CDT or surgery. PMT is associated with incomplete thrombus removal, risk of embolization, and potential for vessel wall and valvular injury (Murphy, 2004). Furthermore, adjunctive PMT procedures often require additional interventional lab time. CATHETER-DIRECTED THROMBOLYSIS CDT involving local delivery of concentrated thrombolytic agents directly into clot is preferred over systemic infusion of thrombolytics due to higher technical success rates and decreased risk of bleeding complications (Sidebar 1). Standard CDT involves continuous, stepwise, or accelerated (e.g., pulse spray technique) infusion of lytic agent through a standard infusion catheter with a hole at the distal end, a series of lateral side holes or lateral slits that open once an intraluminal pressure threshold is reached. Common lytic agents are shown in Table 1. Streptokinase was the first thrombolytic agent to be described and initially the most widely used, but was generally replaced by urokinase (UK) due to increased initial clinical success rates and fewer hemorrhagic complications. Although UK became the most preferred thrombolytic drug, the US Food and Drug Administration temporarily withdrew it from the US market in 1998 due to theoretical concerns of viral disease transmission. During this time, other thrombolytic agents including t-PA and newer drugs were investigated and used with more frequency. Currently, there is no consensus on the optimal thrombolytic drug or dosing regimen for CDT of the peripheral vasculature due to limited data from randomized studies comparing thrombolytic agents (Kessel, Berridge, & Robertson, 2004). CDT has several potential advantages over alternative treatment options. Aside from being less invasive than surgery, CDT may reveal the underlying cause of thrombosis and allow for conversion from emergency to elective surgery. CDT may also be used to
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Sidebar 1. EKOS modes of action 1. Fibrin strand dissociation: Fibrin strands within the clot are loosened, increasing the surface area of the clot exposed to lytic agent. 2. Acoustic microstreaming: Streams of high-flow enhance penetration of lytic agent into thrombus.
resolve thrombus from collateral circulation (Giannini & Balbarini, 2004). Compared to anticoagulation therapy that only inhibits further propagation of thrombus, thrombolysis can more rapidly and completely dissolve existing clot resulting in higher patency rates and preserved venous valvular function (Kahn, 2006). Despite its advantages and demonstrated efficacy in the treatment of PAO and DVT, CDT is associated with complications resulting from prolonged exposure to thrombolytic agents. The most clinically relevant complications associated with CDT are intracranial hemorrhage and stroke (Giannini & Balbarini, 2004; Kessel et al., 2004). Published series estimate the incidence of hemorrhagic stroke at 1% to 2.3% and major bleeding events at 5.1% to 12% when treating arterial occlusions (Ouriel et al., 1998; Working Party on Thrombolysis in the Management of Limb Ischemia, 2003). In the largest published experience of CDT for the treatment of DVT, major bleeding complications were reported in 11% of patients (Mewissen et al., 1999). The number and severity of bleeding complications resulting from CDT are associated with increased time of the thrombolytic infusion and associated increased dose (Sullivan, Gardiner, Shapiro, Bonn, & Levin, 1989). Occlusion duration and extent of disease must be considered to increase the likelihood of technical success. Absolute and relative contraindications must be considered along with risk factors to reduce the possibility of complications. Absolute contraindications to thrombolytic therapy are recent cerebrovascular events (within last 2 months), recent gastrointestinal bleeding (within 10 days), neurosurgery or intracranial trauma (within the last 3 months), and active bleeding diathesis. Relative contraindications are those where the physician must balance the risk versus the potential benefit of using a thrombolytic on a case-by-case basis. Major relative contraindications are cardiopulmonary resuscitation (within 10 days), uncontrolled hypertension,
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major nonvascular surgery (within 10 days), major trauma (within 10 days), noncompressible vessel puncture, intracranial tumor, and recent eye surgery. Relative minor contraindications include hepatic failure (particularly in patients with coagulopathy), bacterial endocarditis, pregnancy, and diabetic hemorrhagic retinopathy (Working Party on Thrombolysis in the Management of Limb Ischemia, 2003). ULTRASOUND ACCELERATED THROMBOLYSIS A new minimally invasive technology, USAT, has been developed to more rapidly and completely resolve arterial and venous occlusions than standard thrombolysis, thereby potentially preventing bleeding complications while avoiding the limitations of percutaneous mechanical techniques and risks of open surgery. USAT combines low-power, high-frequency ultrasound with catheter-directed thrombolytic infusion. Simultaneous delivery of directed ultrasound energy with local thrombolytic infusion accelerates clot lysis through dissociation of fibrin strands and acoustic microstreaming effects. These processes increase clot surface area enhancing receptor site availability, and drive lytic agent deeper into the clot. In addition, ultrasound energy generated from the catheter penetrates through valvular tissue, allowing for complete clearance of clot lodged behind valves (Raabe, 2006). The combined effects of USAT enhance permeability of thrombus to lytic and accelerate thrombolysis, allowing for more rapid and complete clearance of acute and chronic thrombus compared to CDT alone. The efficacy of this technique has been demonstrated in vitro (Braaten, Goss, & Francis, 1997) and clinically in the treatment of patients with embolic stroke (Mahon et al., 2003). USAT using the EKOS EndoWaveÔ System (EKOS Corporation, Bothell, WA) is a new technique that has recently been introduced at our institution. The EKOS infusion catheter is positioned within the thrombus in the interventional radiology (IR) suite and radiology nurses initiate the delivery of ultrasound. Therefore, nurses in the IR department must be familiar in the use of the EKOS system (Sidebar 2). The EKOS system consists of a self-contained control unit and a 5.2-F multilumen drug delivery catheter with matched ultrasound core for combined directed ultrasound and lytic infusion. Treatment zones range from 6 to 50 cm in length depending on the extent of
Table 1. Common thrombolytic medications ActivaseÒ (Genentech, San Francisco, CA) RetavaseÒ (PDL BioPharma, Inc., Fremont, CA) TNKaseÔ (Genentech, San Francisco, CA) AbbokinaseÒ (ImaRx Therapeutics, Inc., Tucson, AZ)
Alteplase (t-PA or rt-PA) Reteplase (rPA) Tenecteplase (TNK) Urokinase (UK)
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Sidebar 2. Patient questions and answers
Sidebar 3. EKOS troubleshooting steps
1. What is the EKOS system doing? The EKOS system provides harmless low-power ultrasound energy (sound waves), while the clot-dissolving drug is being delivered to the clot to make the clot accept more drug and dissolve faster. 2. Will I feel the ultrasound? No, most patients do not feel any effects from the EKOS system because it generates very low-power sound waves. A small percentage of patients describe a feeling of tingling. 3. Will my foot get warm from the ultrasound? No, not as a direct result of the ultrasound. However, when blood flow is restored, the entire limb will get warmer. 4. What does the EKOS display show? The EKOS system automatically adjusts the power of the ultrasound being delivered based on the temperature in the treated area. The display shows the percent of the maximum power that is being delivered. In some cases, the power level shows an upward changedthis usually indicates when blood flow has restarted. There are no ‘‘right’’ or ‘‘wrong’’ power levels because the EKOS system always delivers the optimal power.
1. Mute the alarm. 2. Check the connections. 3. Restart ultrasound by pressing the green ‘‘ON’’ button.
the thrombus, and the catheter contains multiple drug delivery lumens and one central lumen to house the matching ultrasound core wire. Miniature ultrasound transducers are located at approximately 1-cm increments along the distal end of the ultrasound core wire. These elements deliver ultrasound energy radially along the entire infusion zone. Interventional radiologists position the EKOS infusion catheter within the thrombus using their standard navigation techniques with a 0.035-inch guidewire. Because USAT uses the same catheter placement technique as CDT and does not require additional manipulations such as is the case with adjunctive PMT, the procedure requires little time in the IR lab and is associated with a short learning curve. After catheter placement, the guidewire is replaced with the ultrasound core and continuous thrombolytic infusion through the drug delivery lumens is initiated using an infusion pump. At our institution, radiology nurses initiate ultrasound delivery as soon as drug delivery begins to minimize infusion time. The EKOS system has proven to be very user friendly. The drug delivery catheter is connected to the control unit using two electrical connectors that are easily identified with both shape and color coding. Starting the ultrasound is a simple, one-step process that involves pressing a single green ‘‘On’’ button (Sidebar 3). The EndoWave control unit automatically monitors vessel temperature through a series of thermocouples located within the catheter and adjusts ultrasound delivery automatically to maintain optimal- and safe-operating parameters with no input required from the user. As clot dissolves and recanalization occurs, power is automatically increased to the 18
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transducers in the area of increased blood flow. This power change is displayed graphically on the control unit and may serve as an early indicator of clot clearance for potential early angiographic assessment. After catheter placement and initiation of thrombolytic infusion with concomitant ultrasound application, patients are transferred from the IR suite to the critical care unit. For this reason, it is important that nurses working in the intensive care unit (ICU), pediatric intensive care unit, and lytic infusion care units of the hospital also be knowledgeable on this new technology. At our institution, all hospital departments involved in monitoring thrombolytic patients have been in-serviced on the EKOS system. However, because not all ICU nurses will have experience using the system when it arrives with a patient, radiology nurses must be prepared to provide an overview of the EKOS system to ensure the patient receives the full benefit of this novel technology. A brief summary of the technique for the ICU nurse should include the following points: 1. Ultrasound pushes drug away from the catheter to the surrounding clot. It also thins and separates the fibrin strands within the clot allowing the drug to access more of the clot surface. Simultaneous thrombolytic drug delivery with the application of low-power ultrasound accelerates clot lysis to minimize procedure time. 2. The drug delivery catheter is connected to the control unit with two connectors, one gray and one black. The most common alarm occurs when one of these connectors becomes disconnected. To resolve the alarm, the connections should be checked and ultrasound restarted by pressing the green ‘‘On’’ button. 3. Standard hospital infusion pumps are used to deliver thrombolytic drug through the drug delivery catheter so there is no change when addressing pump alarm issues. Nurses should ensure that physician-specified flow rates for both drug and coolant are maintained. 4. The EKOS system is automatically monitoring the ultrasound and ensuring there are no patient safety issues. CASE STUDY A 66-year-old female with a history of peripheral vascular disease and smoking (stopped 20 years prior)
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presented with pain in her right leg. She had a right femoral-tibial peroneal bypass graft implanted 18 months prior with a right femoral-popliteal and aortobifemoral bypass grafts placed before that (Figure 1).
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The patient presented with acute right leg pain and reported that she had had intermittent rest pain in her right leg since 1-month postgraft implant. Lower extremity angiography confirmed a right femoral-tibial
Figure 1. A 66-year-old female with a history of peripheral vascular disease and acute onset of pain had a total occlusion (A) of her femoral-tibial peroneal bypass graft. B. A 50-cm long EKOS infusion catheter was placed through the graft. C. After 21.5 hr of thrombolysis, the arteriogram shows the graft is patent with complete clot lysis.
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peroneal bypass graft occlusion. There was reconstitution in the tibial peroneal artery in the upper calf region. Vascular access was contralateral from the left common femoral artery. A 7 40 Balkin sheath (Cook Inc., Bloomington, IN) was advanced retrograde into the right limb of the aortobifemoral graft. Access through the occlusion was gained using an MPA catheter (Cordis, Miami Lakes, FL) and 0.035-inch guidewire. Due to the extent of the occlusion and the need for rapid and complete removal of thrombus, USAT was selected as the treatment option. An EndoWave catheter (EKOS Corporation, Bothell, WA) with the longest available treatment length (50 cm) was used due to the length of the thrombus. The catheter was advanced over the guidewire through the occluded graft. Reteplase (RetavaseÒ, PDL BioPharma, Inc. Fremont, CA) was administered through the infusion catheter at a dose of 0.25 U/hr. The EndoWave catheter coolant lumen was infused with heparinized saline at a rate of 20 mL/hr. Ultrasound was started and the patient was transferred to the ICU. In addition to the reteplase, intravenous heparin was infused at 80 U/hr, half through the coolant lumen and half through the sheath, to maintain the partial thromboplastin time at 40e50 s. Due to the extent of the thrombus and likelihood that the clot contained chronic components, it was determined that the patient would get her first lytic check after a full day of thrombolytic infusion (approximately 24 hr). Our expectation was that the patient would return to the ICU for additional thrombolytic infusion after the initial angiographic assessment. Pulses were taken regularly and after 1 hr, the dorsalis pedis pulse in the right lower extremity was detected using Doppler. The lytic check at 21.5 hr showed a patent bypass graft with minimal residual thrombus. A total dose of 5-U reteplase was delivered. There was a moderately atherosclerotic irregularity at the anastamosis of the graft in the common femoral artery that resulted in 60% to 70% stenosis. This stenosis was successfully treated with angioplasty using a 5 6-cm balloon, resulting in excellent angiographic results and improved blood flow. Postprocedure, there was complete resolution of symptoms. The patient was discharged on postprocedure day 4. At her 1-month follow-up visit, the right leg was warm and the patient was not experiencing any leg pain. Pulses in the right common femoral artery were palpable and 2+ and the pulses in the posterior tibial artery were palpable and 1+. USAT provided a fast, effective treatment for this occluded femoral-tibial peroneal bypass graft. CONCLUSION Occlusions of the peripheral vasculature are serious conditions with significant rates of morbidity and 20
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mortality (Augustinos & Ouriel, 2004; Ouriel, 2002). Profound limb ischemia requires rapid recanalization through an interventional procedure or surgical treatment (Ouriel, 2002). In addition to resolving symptoms, rapid elimination of residual thrombus in DVT patients may prevent serious complications including acute PE and the development of chronic PTS. USAT is an interventional procedure that has been developed to more rapidly and completely resolve existing thrombus compared to traditional endovascular techniques while avoiding the risks of open surgery. At our institution, USAT achieved early recanalization and complete clot lysis with only an overnight infusion in an occluded right femoral-tibial peroneal bypass graft that had been symptomatic for over 12 months. Patients undergoing USAT are transferred from the IR suite to the critical care unit, necessitating an understanding of the clinical implications of peripheral vascular occlusions and this new technique by nurses in the IR department, ICU, and lytic units. The EKOS EndoWave is a self-contained, easy-to-use system with automated monitoring that uses the same placement technique as CDT, a well-accepted treatment for PAO and DVT. USAT provides significant patient benefit by potentially decreasing lytic infusion duration and reducing drug dosage leading to fewer hemorrhagic complications and eliminating residual thrombus. References AbuRahma, A., Perkins, S.E., Wulu, J.T., & Ng, H.K. (2001). Iliofemoral deep vein thrombosis: Conventional therapy versus lysis and percutaneous transluminal angioplasty and stenting. Annals of Surgery, 233(6), 752-760. Allaqaband, S., Solis, J., Kazemi, S., & Bajwa, T. (2006). Endovascular treatment of peripheral vascular disease. Current Problems in Cardiology, 31(11), 711-760. Augustinos, P., & Ouriel, K. (2004). Invasive approaches to treatment of venous thromboembolism. Circulation, 110(Suppl. I), I27-I34. Braaten, J.V., Goss, R.A., & Francis, C.W. (1997). Ultrasound reversibly disaggregates fibrin fibers. Thrombosis and Haemostasis, 78(3), 1063-1068. Clagett, G.P., Sobel, M., Jackson, M.R., Lip, G.Y., Tangelder, M., & Verhaeghe, R. (2004). Antithrombotic therapy in peripheral arterial occlusive disease: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest, 126(3 Suppl.), 609S-626S. Davies, B., Braithwaite, B.D., Birch, P.A., Poskitt, K.R., Heather, B.P., & Earnshaw, J.J. (1997). Acute leg ischaemia in Gloucestershire. The British Journal of Surgery, 84(4), 504-508. Dormandy, J.A., & Rutherford, R.B. (2000). Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic Inter-Society Consensus (TASC). Journal of Vascular Surgery, 31(1 Pt 2), S1-S296. Elman, E.E., & Kahn, S.R. (2006). The post-thrombotic syndrome after upper extremity deep venous thrombosis in adults: A systematic review. Thrombosis Research, 117(6), 609-614.
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Giannini, D., & Balbarini, A. (2004). Thrombolytic therapy in peripheral arterial disease. Current Drug TargetsdCardiovascular & Haematological Disorders, 4(3), 249-258. Grimm, J., Jahnke, T., Muhle, C., Heller, M., & Mu¨ller-Hu¨lsbeck, S. (2003). Influence of thrombus age on the mechanical thrombectomy efficacy of the Amplatz thrombectomy device in vitro. Cardiovascular and Interventional Radiology, 26(3), 265-268. Haines, S.T. (2003). Venous thromboembolism: Pathophysiology and clinical presentation. American Journal of Health-System Pharmacy, 60(22 Suppl. 7), S3-S5. Hirsch, A.T., & Criqui, M.H. (2001). Peripheral arterial disease detection, awareness, and treatment in primary care. Journal of the American Medical Association, 286(11), 1317-1324. Kahn, S.R. (2006). The post-thrombotic syndrome: Progress and pitfalls. British Journal of Haematology, 134(4), 357-365. Kalinowski, M., & Wagner, H. (2003). Adjunctive techniques in percutaneous mechanical thrombectomy. Techniques in Vascular and Interventional Radiology, 6(1), 6-13. Kessel, D.O., Berridge, D.C., & Robertson, I. (2004). Infusion techniques for peripheral arterial thrombolysis. Cochrane Database of Systematic Reviews, 1. CD000985. Kommareddy, A., Zaroukian, M.H., & Hassouna, H.I. (2002). Upper extremity deep vein thrombosis. Seminars in Thrombosis and Hemostasis, 28(1), 89-99. Laiho, M.K., Oinonen, A., Sugano, N., Harjola, V.-P., Lehtola, A.L., & Roth, W.-D., et al. (2004). Preservation of venous valve function after catheter-directed and systemic thrombolysis for deep venous thrombosis. European Journal of Vascular and Endovascular Surgery, 28(4), 391-396. Mahon, B.R., Nesbit, G.M., Barnwell, S.L., Clark, W., Marotta, T.R., & Weill, A., et al. (2003). North American clinical experience with the EKOS MicroLysUS Infusion Catheter for the treatment of embolic stroke. ANJR American Journal of Neuroradiology, 24(3), 534-538. Mewissen, M.W., Seabrook, G.R., Meissner, M.H., Cynamon, J., Labropoulos, N., & Haughton, S.H. (1999). Catheter-directed
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thrombolysis of lower extremity deep venous thrombosis: Report of a national multicenter registry. Radiology, 211(1), 39-49. Murphy, K.D. (2004). Mechanical thrombectomy for DVT. Techniques in Vascular and Interventional Radiology, 7(2), 79-85. Ouriel, K. (2002). Current status of thrombolysis for peripheral arterial occlusive disease. Annals of Vascular Surgery, 16(6), 797-804. Ouriel, K., Veith, F.J., & Sasahara, A.A. (1998). A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. Thrombolysis or Peripheral Arterial Surgery (TOPAS) Investigators. New England Journal of Medicine, 338(16), 1105-1111. Raabe, R.A. (2006). Ultrasound-facilitated thrombolysis in treating DVT. Endovascular Today, 5(4), 75-79. Semba, C.P., Razavi, M.K., Kee, S.T., Sze, D.Y., & Dake, M.D. (2004). Thrombolysis for lower extremity deep venous thrombosis. Techniques in Vascular and Interventional Radiology, 7(2), 68-78. Sharafuddin, M.J., Shilian, S., Hoballah, J.J., Youness, F.M., Sharp, W.J., & Roh, B. (2003). Endovascular management of venous thrombotic and occlusive diseases of the lower extremities. Journal of Vascular and Interventional Radiology, 14(4), 405-423. Sieggreen, M. (2006). A contemporary approach to peripheral vascular disease. The Nurse Practitioner, 31(7), 14-25. Sullivan, K.L., Gardiner, G.A., Jr., Shapiro, M.J., Bonn, J., & Levin, D.C. (1989). Acceleration of thrombolysis with a highdose transthrombus bolus technique. Radiology, 173(3), 805-808. Working Party on Thrombolysis in the Management of Limb Ischemia. (2003). Thrombolysis in the management of lower limb peripheral arterial occlusiondA consensus document. Journal of Vascular and Interventional Radiology, 14(9 Pt 2), S337-S349.
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INTRODUCTION Occlusions of the peripheral arteries and veins are common and serious conditions that can lead to pain, limb loss, or even death. Although treatment ranges from pharmacotherapy to open surgery, many patients are also seen in the angiography suite to be treated with interventions such as catheter-directed thrombolysis (CDT), percutaneous mechanical thrombectomy (PMT) and a novel technique, ultrasound accelerated thrombolysis (USAT). When a stenosis is revealed, it
Stephanie D. Crouch, RN, Deborah Hill, RN, and Donna Bridwell RT (R) (VI), are with Interventional Radiology Department, St. Anthony’s Medical Center, at St. Louis, MO. The authors hold no financial interest in any product or manufacturer mentioned in the article. Corresponding author Stephanie D. Crouch, Interventional Radiology Department, St. Anthony’s Medical Center, 10010 Kennerly Road, St. Louis, MO 63128. E-mail: [email protected] 1546-0843/$34.00 Copyright Ó 2008 by the American Radiological Nurses Association. doi: 10.1016/j.jradnu.2007.12.002
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is resolved with a procedure such as angioplasty, stent implantation, or plaque excision. It is important for radiology nurses caring for patients being treated for arterial or venous occlusions to understand the risk factors, presentation, treatment options, and the new technology available to improve outcomes. Our case study illustrates the successful use of USAT in a patient with extensive and potentially chronic thrombus in the lower extremity. The patient presented with acute onset of right extremity pain and a history of vascular disease. After treatment with USAT, this patient experienced early recanalization and complete thrombus resolution of her occluded femoral-tibial peroneal bypass graft with only an overnight infusion. USAT unmasked an underlying lesion that was successfully treated with angioplasty and at 1 month, the patient continued to have pulses and had no leg pain. PERIPHERAL ARTERIAL DISEASE AND OCCLUSIONS Peripheral arterial disease (PAD) is a common condition whose symptoms affect approximately 10 million
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people in the United States. An additional 20 to 30 million Americans have asymptomatic PAD (Allaqaband, Solis, Kazemi, & Bajwa, 2006; Hirsch & Criqui, 2001). Patients affected with the disease have an increased risk of cardiovascular events and mortality. PAD is characterized by reduced blood flow in limb arteries, typically the legs, and is most frequently caused by atherosclerotic plaque buildup that causes narrowing of the arterial lumen. Narrow, diseased vessels are more prone to occlusion by an embolus, thrombus, or acute trauma. The prevalence of peripheral arterial occlusion (PAO) is estimated to be 14 out of 100,000 (Davies et al., 1997; Giannini & Balbarini, 2004). When clot blocks blood flow into the affected limb, the patient experiences pain, a cold, or blue leg and is at risk for amputation. Similar to coronary artery disease, key risk factors for PAD include tobacco use, diabetes mellitus, hypertension, high cholesterol, family history, obesity, dyslipidemia, and increasing age (Clagett et al., 2004; Sieggreen, 2006). PAD patients have a wide variety of presenting symptoms with a marked difference between chronic and acute onset. Patients with chronic disease often experience pain during walking, known as intermittent claudication. This is the most common symptom of lower extremity PAD, present in up to 20% of patients older than 75 years (Sieggreen, 2006). Approximately 25% of patients with intermittent claudication will deteriorate to more severe disease (Dormandy & Rutherford, 2000). More serious symptoms of chronic PAD include critical limb ischemia, characterized by rest pain and indicating that there is insufficient blood flow to sustain tissue. Often, this progresses to ischemic ulcers or gangrene. If blood flow is not reestablished, these conditions may lead to amputation, which becomes necessary in 1% to 3% of symptomatic patients (Dormandy & Rutherford, 2000). Acute onset of an arterial occlusion, as a first occurrence or in a patient with chronic disease, is most commonly caused by underlying atherosclerosis and the sudden loss of blood flow due to clot formation in a native artery or bypass. Due to the abrupt development of the occlusion, collateral blood supply is not well established resulting in ischemia. Patients with severe acute occlusion present with pain followed by paresthesia, motor dysfunction, and eventual tissue death (Ouriel, 2002). Acute limb ischemia threatens the viability of the extremity and is associated with a 1-year mortality rate of approximately 20% (Ouriel, 2002). Management of PAOs depends on many factors including extent and location of the disease, patient comorbidities, occlusion duration (e.g., acute or chronic), and type of occlusion (e.g., embolic or thrombotic). Initial treatment for PAD without limb ischemia includes
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exercise, risk factor modification, and pharmacotherapy to reduce symptoms and help control the disease. Risk factor modification includes smoking cessation to slow the progression of PAD and lower risk of cardiovascular events, as well as weight loss, blood pressure reduction, blood glucose control, and lipid modification to reduce cardiovascular morbidity and mortality (Sieggreen, 2006). Antiplatelet therapy with aspirin and clopidogrel is initiated to inhibit thrombus propagation (Allaqaband et al., 2006; Clagett et al., 2004; Ouriel, 2002). Medical therapy decreases the risk of associated cardiovascular events and lowers the risk of recurrent thrombosis (Clagett et al., 2004; Sieggreen, 2006). Patients with disabling claudication and profound limb ischemia require more aggressive treatment such as endovascular interventions or open surgery to restore blood flow quickly (Ouriel, 2002). Historically, open surgical techniques such as thromboembolectomy or bypass grafting have been the primary treatment for acute limb ischemia. However, patients with PAD tend to be medically compromised due to comorbid conditions such as coronary artery disease and cerebrovascular disease that associate open surgical procedures with a significant mortality rate (Ouriel, 2002; Ouriel, Veith, & Sasahara, 1998). In fact, due to related complications, surgical intervention for the treatment of acute limb ischemia is associated with a 30-day mortality rate of up to 25% (Ouriel et al., 1998). For this reason, less invasive interventional procedures such as CDT and PMT have become widely accepted alternatives to surgery. Although CDT has demonstrated comparable or favorable morbidity and mortality rates to open surgery, extended duration of thrombolytic infusion and large drug dosages required to achieve recanalization of the vessel may lead to serious hemorrhagic complications. PMT devices have demonstrated efficacy in rapidly macerating and extracting thrombus, but with limited effectiveness in older occlusions and increased potential for distal embolization and residual thrombus (Grimm, Jahnke, Muhle, Heller, & Mu¨ller-Hu¨lsbeck, 2003; Kalinowski & Wagner, 2003). For these reasons, PMT is generally used as an adjunct to CDT rather than as a stand-alone treatment. DEEP VENOUS THROMBOSIS Deep venous thrombosis (DVT), the most common manifestation of venous thromboembolism, occurs in as many as 250,000 Americans each year (Augustinos & Ouriel, 2004). DVT typically occurs in the deep veins of the lower extremities; however, upper extremities are involved in approximately 4% of cases (Elman & Kahn, 2006; Kommareddy, Zaroukian, & Hassouna, 2002). Patients with acute DVT typically present with
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symptoms that abate over time with the development of collateral pathways including limb edema, pain, and difficulty with walking. However, many patients continue to experience symptoms due to outflow obstruction, particularly during exercise (Augustinos & Ouriel, 2004). DVT is associated with disabling and potentially life-threatening acute and chronic complications. The most serious complication of DVT is pulmonary embolism, resulting in as many as 100,000 deaths annually in the United States (Haines, 2003). Other complications of DVT include recurrent thrombosis, which occurs in up to 10% of DVT patients within 3 years, and may cause symptoms and complications including pulmonary embolism (PE) (Augustinos & Ouriel, 2004). Postthrombotic syndrome (PTS), the most common DVT complication found in two thirds of patients with iliofemoral DVT, refers to chronic venous insufficiency resulting from valvular incompetence and venous obstruction (Augustinos & Ouriel, 2004; Laiho et al., 2004). Patients with PTS present with a wide spectrum of symptoms including limb edema, leg heaviness, claudication, hyperpigmentation and, in severe cases, ulceration (Augustinos & Ouriel, 2004; Semba, Razavi, Kee, Sze, & Dake, 2004). Virchow’s triad highlights the following causes of venous thrombosis: endothelial injury, blood flow abnormalities, and hypercoagulability. Specific risk factors for DVT include recent surgery, bed rest, orthopedic surgery, advanced age, cardiac disease, malignancy, immobilization, spinal injury, leg trauma, pregnancy, acquired and inherited hypercoagulable states, use of oral contraceptives, obesity, presence of intravenous access devices, and previous episodes of venous thrombosis (Sharafuddin et al., 2003). In younger women, the compression of the left iliac vein by the artery crossing over it, known as May-Thurner Syndrome, is a common contributing factor in DVT. Treatment for DVT ranges from anticoagulation therapy to surgical intervention. The goal of the treatment is to reduce symptom severity and prevent acute and late complications such as PE, recurrent thrombosis, and PTS. The standard of care for DVT is anticoagulation therapy with unfractionated or low-molecular-weight heparin followed by oral anticoagulants. Inferior vena cava filters are indicated to prevent PE in DVT patients who are contraindicated for anticoagulation therapy. Although anticoagulation prevents further thrombus formation, it does not dissolve the existing occlusion. This limitation results in a significant number of patients with residual thrombus that leads to low long-term patency rates (AbuRahma et al., 2001). Surgical thrombectomy provides rapid and complete removal of occlusive thrombus; however,
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this technique has been associated with a high-recurrence rate and significant mortality (Ouriel et al., 1998). For these reasons, surgical thrombectomy is typically reserved for patients contraindicated or refractory to other treatments. Interventional procedures for DVT including CDT and PMT attempt to resolve existing thrombus without the inherent risks of open surgery. CDT has become an accepted DVT treatment in select patients and has demonstrated efficacy in achieving complete and partial lysis. However, extended lysis times, over 48 hr in many cases, and the associated risk of hemorrhagic complications have prevented more widespread use of this technique in the treatment of DVT (Semba et al., 2004). PMT devices, designed to fragment and extract thrombus, are used as stand-alone therapy or as an adjunct to CDT or surgery. PMT is associated with incomplete thrombus removal, risk of embolization, and potential for vessel wall and valvular injury (Murphy, 2004). Furthermore, adjunctive PMT procedures often require additional interventional lab time. CATHETER-DIRECTED THROMBOLYSIS CDT involving local delivery of concentrated thrombolytic agents directly into clot is preferred over systemic infusion of thrombolytics due to higher technical success rates and decreased risk of bleeding complications (Sidebar 1). Standard CDT involves continuous, stepwise, or accelerated (e.g., pulse spray technique) infusion of lytic agent through a standard infusion catheter with a hole at the distal end, a series of lateral side holes or lateral slits that open once an intraluminal pressure threshold is reached. Common lytic agents are shown in Table 1. Streptokinase was the first thrombolytic agent to be described and initially the most widely used, but was generally replaced by urokinase (UK) due to increased initial clinical success rates and fewer hemorrhagic complications. Although UK became the most preferred thrombolytic drug, the US Food and Drug Administration temporarily withdrew it from the US market in 1998 due to theoretical concerns of viral disease transmission. During this time, other thrombolytic agents including t-PA and newer drugs were investigated and used with more frequency. Currently, there is no consensus on the optimal thrombolytic drug or dosing regimen for CDT of the peripheral vasculature due to limited data from randomized studies comparing thrombolytic agents (Kessel, Berridge, & Robertson, 2004). CDT has several potential advantages over alternative treatment options. Aside from being less invasive than surgery, CDT may reveal the underlying cause of thrombosis and allow for conversion from emergency to elective surgery. CDT may also be used to
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Sidebar 1. EKOS modes of action 1. Fibrin strand dissociation: Fibrin strands within the clot are loosened, increasing the surface area of the clot exposed to lytic agent. 2. Acoustic microstreaming: Streams of high-flow enhance penetration of lytic agent into thrombus.
resolve thrombus from collateral circulation (Giannini & Balbarini, 2004). Compared to anticoagulation therapy that only inhibits further propagation of thrombus, thrombolysis can more rapidly and completely dissolve existing clot resulting in higher patency rates and preserved venous valvular function (Kahn, 2006). Despite its advantages and demonstrated efficacy in the treatment of PAO and DVT, CDT is associated with complications resulting from prolonged exposure to thrombolytic agents. The most clinically relevant complications associated with CDT are intracranial hemorrhage and stroke (Giannini & Balbarini, 2004; Kessel et al., 2004). Published series estimate the incidence of hemorrhagic stroke at 1% to 2.3% and major bleeding events at 5.1% to 12% when treating arterial occlusions (Ouriel et al., 1998; Working Party on Thrombolysis in the Management of Limb Ischemia, 2003). In the largest published experience of CDT for the treatment of DVT, major bleeding complications were reported in 11% of patients (Mewissen et al., 1999). The number and severity of bleeding complications resulting from CDT are associated with increased time of the thrombolytic infusion and associated increased dose (Sullivan, Gardiner, Shapiro, Bonn, & Levin, 1989). Occlusion duration and extent of disease must be considered to increase the likelihood of technical success. Absolute and relative contraindications must be considered along with risk factors to reduce the possibility of complications. Absolute contraindications to thrombolytic therapy are recent cerebrovascular events (within last 2 months), recent gastrointestinal bleeding (within 10 days), neurosurgery or intracranial trauma (within the last 3 months), and active bleeding diathesis. Relative contraindications are those where the physician must balance the risk versus the potential benefit of using a thrombolytic on a case-by-case basis. Major relative contraindications are cardiopulmonary resuscitation (within 10 days), uncontrolled hypertension,
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major nonvascular surgery (within 10 days), major trauma (within 10 days), noncompressible vessel puncture, intracranial tumor, and recent eye surgery. Relative minor contraindications include hepatic failure (particularly in patients with coagulopathy), bacterial endocarditis, pregnancy, and diabetic hemorrhagic retinopathy (Working Party on Thrombolysis in the Management of Limb Ischemia, 2003). ULTRASOUND ACCELERATED THROMBOLYSIS A new minimally invasive technology, USAT, has been developed to more rapidly and completely resolve arterial and venous occlusions than standard thrombolysis, thereby potentially preventing bleeding complications while avoiding the limitations of percutaneous mechanical techniques and risks of open surgery. USAT combines low-power, high-frequency ultrasound with catheter-directed thrombolytic infusion. Simultaneous delivery of directed ultrasound energy with local thrombolytic infusion accelerates clot lysis through dissociation of fibrin strands and acoustic microstreaming effects. These processes increase clot surface area enhancing receptor site availability, and drive lytic agent deeper into the clot. In addition, ultrasound energy generated from the catheter penetrates through valvular tissue, allowing for complete clearance of clot lodged behind valves (Raabe, 2006). The combined effects of USAT enhance permeability of thrombus to lytic and accelerate thrombolysis, allowing for more rapid and complete clearance of acute and chronic thrombus compared to CDT alone. The efficacy of this technique has been demonstrated in vitro (Braaten, Goss, & Francis, 1997) and clinically in the treatment of patients with embolic stroke (Mahon et al., 2003). USAT using the EKOS EndoWaveÔ System (EKOS Corporation, Bothell, WA) is a new technique that has recently been introduced at our institution. The EKOS infusion catheter is positioned within the thrombus in the interventional radiology (IR) suite and radiology nurses initiate the delivery of ultrasound. Therefore, nurses in the IR department must be familiar in the use of the EKOS system (Sidebar 2). The EKOS system consists of a self-contained control unit and a 5.2-F multilumen drug delivery catheter with matched ultrasound core for combined directed ultrasound and lytic infusion. Treatment zones range from 6 to 50 cm in length depending on the extent of
Table 1. Common thrombolytic medications ActivaseÒ (Genentech, San Francisco, CA) RetavaseÒ (PDL BioPharma, Inc., Fremont, CA) TNKaseÔ (Genentech, San Francisco, CA) AbbokinaseÒ (ImaRx Therapeutics, Inc., Tucson, AZ)
Alteplase (t-PA or rt-PA) Reteplase (rPA) Tenecteplase (TNK) Urokinase (UK)
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Sidebar 2. Patient questions and answers
Sidebar 3. EKOS troubleshooting steps
1. What is the EKOS system doing? The EKOS system provides harmless low-power ultrasound energy (sound waves), while the clot-dissolving drug is being delivered to the clot to make the clot accept more drug and dissolve faster. 2. Will I feel the ultrasound? No, most patients do not feel any effects from the EKOS system because it generates very low-power sound waves. A small percentage of patients describe a feeling of tingling. 3. Will my foot get warm from the ultrasound? No, not as a direct result of the ultrasound. However, when blood flow is restored, the entire limb will get warmer. 4. What does the EKOS display show? The EKOS system automatically adjusts the power of the ultrasound being delivered based on the temperature in the treated area. The display shows the percent of the maximum power that is being delivered. In some cases, the power level shows an upward changedthis usually indicates when blood flow has restarted. There are no ‘‘right’’ or ‘‘wrong’’ power levels because the EKOS system always delivers the optimal power.
1. Mute the alarm. 2. Check the connections. 3. Restart ultrasound by pressing the green ‘‘ON’’ button.
the thrombus, and the catheter contains multiple drug delivery lumens and one central lumen to house the matching ultrasound core wire. Miniature ultrasound transducers are located at approximately 1-cm increments along the distal end of the ultrasound core wire. These elements deliver ultrasound energy radially along the entire infusion zone. Interventional radiologists position the EKOS infusion catheter within the thrombus using their standard navigation techniques with a 0.035-inch guidewire. Because USAT uses the same catheter placement technique as CDT and does not require additional manipulations such as is the case with adjunctive PMT, the procedure requires little time in the IR lab and is associated with a short learning curve. After catheter placement, the guidewire is replaced with the ultrasound core and continuous thrombolytic infusion through the drug delivery lumens is initiated using an infusion pump. At our institution, radiology nurses initiate ultrasound delivery as soon as drug delivery begins to minimize infusion time. The EKOS system has proven to be very user friendly. The drug delivery catheter is connected to the control unit using two electrical connectors that are easily identified with both shape and color coding. Starting the ultrasound is a simple, one-step process that involves pressing a single green ‘‘On’’ button (Sidebar 3). The EndoWave control unit automatically monitors vessel temperature through a series of thermocouples located within the catheter and adjusts ultrasound delivery automatically to maintain optimal- and safe-operating parameters with no input required from the user. As clot dissolves and recanalization occurs, power is automatically increased to the 18
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transducers in the area of increased blood flow. This power change is displayed graphically on the control unit and may serve as an early indicator of clot clearance for potential early angiographic assessment. After catheter placement and initiation of thrombolytic infusion with concomitant ultrasound application, patients are transferred from the IR suite to the critical care unit. For this reason, it is important that nurses working in the intensive care unit (ICU), pediatric intensive care unit, and lytic infusion care units of the hospital also be knowledgeable on this new technology. At our institution, all hospital departments involved in monitoring thrombolytic patients have been in-serviced on the EKOS system. However, because not all ICU nurses will have experience using the system when it arrives with a patient, radiology nurses must be prepared to provide an overview of the EKOS system to ensure the patient receives the full benefit of this novel technology. A brief summary of the technique for the ICU nurse should include the following points: 1. Ultrasound pushes drug away from the catheter to the surrounding clot. It also thins and separates the fibrin strands within the clot allowing the drug to access more of the clot surface. Simultaneous thrombolytic drug delivery with the application of low-power ultrasound accelerates clot lysis to minimize procedure time. 2. The drug delivery catheter is connected to the control unit with two connectors, one gray and one black. The most common alarm occurs when one of these connectors becomes disconnected. To resolve the alarm, the connections should be checked and ultrasound restarted by pressing the green ‘‘On’’ button. 3. Standard hospital infusion pumps are used to deliver thrombolytic drug through the drug delivery catheter so there is no change when addressing pump alarm issues. Nurses should ensure that physician-specified flow rates for both drug and coolant are maintained. 4. The EKOS system is automatically monitoring the ultrasound and ensuring there are no patient safety issues. CASE STUDY A 66-year-old female with a history of peripheral vascular disease and smoking (stopped 20 years prior)
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presented with pain in her right leg. She had a right femoral-tibial peroneal bypass graft implanted 18 months prior with a right femoral-popliteal and aortobifemoral bypass grafts placed before that (Figure 1).
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The patient presented with acute right leg pain and reported that she had had intermittent rest pain in her right leg since 1-month postgraft implant. Lower extremity angiography confirmed a right femoral-tibial
Figure 1. A 66-year-old female with a history of peripheral vascular disease and acute onset of pain had a total occlusion (A) of her femoral-tibial peroneal bypass graft. B. A 50-cm long EKOS infusion catheter was placed through the graft. C. After 21.5 hr of thrombolysis, the arteriogram shows the graft is patent with complete clot lysis.
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peroneal bypass graft occlusion. There was reconstitution in the tibial peroneal artery in the upper calf region. Vascular access was contralateral from the left common femoral artery. A 7 40 Balkin sheath (Cook Inc., Bloomington, IN) was advanced retrograde into the right limb of the aortobifemoral graft. Access through the occlusion was gained using an MPA catheter (Cordis, Miami Lakes, FL) and 0.035-inch guidewire. Due to the extent of the occlusion and the need for rapid and complete removal of thrombus, USAT was selected as the treatment option. An EndoWave catheter (EKOS Corporation, Bothell, WA) with the longest available treatment length (50 cm) was used due to the length of the thrombus. The catheter was advanced over the guidewire through the occluded graft. Reteplase (RetavaseÒ, PDL BioPharma, Inc. Fremont, CA) was administered through the infusion catheter at a dose of 0.25 U/hr. The EndoWave catheter coolant lumen was infused with heparinized saline at a rate of 20 mL/hr. Ultrasound was started and the patient was transferred to the ICU. In addition to the reteplase, intravenous heparin was infused at 80 U/hr, half through the coolant lumen and half through the sheath, to maintain the partial thromboplastin time at 40e50 s. Due to the extent of the thrombus and likelihood that the clot contained chronic components, it was determined that the patient would get her first lytic check after a full day of thrombolytic infusion (approximately 24 hr). Our expectation was that the patient would return to the ICU for additional thrombolytic infusion after the initial angiographic assessment. Pulses were taken regularly and after 1 hr, the dorsalis pedis pulse in the right lower extremity was detected using Doppler. The lytic check at 21.5 hr showed a patent bypass graft with minimal residual thrombus. A total dose of 5-U reteplase was delivered. There was a moderately atherosclerotic irregularity at the anastamosis of the graft in the common femoral artery that resulted in 60% to 70% stenosis. This stenosis was successfully treated with angioplasty using a 5 6-cm balloon, resulting in excellent angiographic results and improved blood flow. Postprocedure, there was complete resolution of symptoms. The patient was discharged on postprocedure day 4. At her 1-month follow-up visit, the right leg was warm and the patient was not experiencing any leg pain. Pulses in the right common femoral artery were palpable and 2+ and the pulses in the posterior tibial artery were palpable and 1+. USAT provided a fast, effective treatment for this occluded femoral-tibial peroneal bypass graft. CONCLUSION Occlusions of the peripheral vasculature are serious conditions with significant rates of morbidity and 20
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mortality (Augustinos & Ouriel, 2004; Ouriel, 2002). Profound limb ischemia requires rapid recanalization through an interventional procedure or surgical treatment (Ouriel, 2002). In addition to resolving symptoms, rapid elimination of residual thrombus in DVT patients may prevent serious complications including acute PE and the development of chronic PTS. USAT is an interventional procedure that has been developed to more rapidly and completely resolve existing thrombus compared to traditional endovascular techniques while avoiding the risks of open surgery. At our institution, USAT achieved early recanalization and complete clot lysis with only an overnight infusion in an occluded right femoral-tibial peroneal bypass graft that had been symptomatic for over 12 months. Patients undergoing USAT are transferred from the IR suite to the critical care unit, necessitating an understanding of the clinical implications of peripheral vascular occlusions and this new technique by nurses in the IR department, ICU, and lytic units. The EKOS EndoWave is a self-contained, easy-to-use system with automated monitoring that uses the same placement technique as CDT, a well-accepted treatment for PAO and DVT. USAT provides significant patient benefit by potentially decreasing lytic infusion duration and reducing drug dosage leading to fewer hemorrhagic complications and eliminating residual thrombus. References AbuRahma, A., Perkins, S.E., Wulu, J.T., & Ng, H.K. (2001). Iliofemoral deep vein thrombosis: Conventional therapy versus lysis and percutaneous transluminal angioplasty and stenting. Annals of Surgery, 233(6), 752-760. Allaqaband, S., Solis, J., Kazemi, S., & Bajwa, T. (2006). Endovascular treatment of peripheral vascular disease. Current Problems in Cardiology, 31(11), 711-760. Augustinos, P., & Ouriel, K. (2004). Invasive approaches to treatment of venous thromboembolism. Circulation, 110(Suppl. I), I27-I34. Braaten, J.V., Goss, R.A., & Francis, C.W. (1997). Ultrasound reversibly disaggregates fibrin fibers. Thrombosis and Haemostasis, 78(3), 1063-1068. Clagett, G.P., Sobel, M., Jackson, M.R., Lip, G.Y., Tangelder, M., & Verhaeghe, R. (2004). Antithrombotic therapy in peripheral arterial occlusive disease: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest, 126(3 Suppl.), 609S-626S. Davies, B., Braithwaite, B.D., Birch, P.A., Poskitt, K.R., Heather, B.P., & Earnshaw, J.J. (1997). Acute leg ischaemia in Gloucestershire. The British Journal of Surgery, 84(4), 504-508. Dormandy, J.A., & Rutherford, R.B. (2000). Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic Inter-Society Consensus (TASC). Journal of Vascular Surgery, 31(1 Pt 2), S1-S296. Elman, E.E., & Kahn, S.R. (2006). The post-thrombotic syndrome after upper extremity deep venous thrombosis in adults: A systematic review. Thrombosis Research, 117(6), 609-614.
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Giannini, D., & Balbarini, A. (2004). Thrombolytic therapy in peripheral arterial disease. Current Drug TargetsdCardiovascular & Haematological Disorders, 4(3), 249-258. Grimm, J., Jahnke, T., Muhle, C., Heller, M., & Mu¨ller-Hu¨lsbeck, S. (2003). Influence of thrombus age on the mechanical thrombectomy efficacy of the Amplatz thrombectomy device in vitro. Cardiovascular and Interventional Radiology, 26(3), 265-268. Haines, S.T. (2003). Venous thromboembolism: Pathophysiology and clinical presentation. American Journal of Health-System Pharmacy, 60(22 Suppl. 7), S3-S5. Hirsch, A.T., & Criqui, M.H. (2001). Peripheral arterial disease detection, awareness, and treatment in primary care. Journal of the American Medical Association, 286(11), 1317-1324. Kahn, S.R. (2006). The post-thrombotic syndrome: Progress and pitfalls. British Journal of Haematology, 134(4), 357-365. Kalinowski, M., & Wagner, H. (2003). Adjunctive techniques in percutaneous mechanical thrombectomy. Techniques in Vascular and Interventional Radiology, 6(1), 6-13. Kessel, D.O., Berridge, D.C., & Robertson, I. (2004). Infusion techniques for peripheral arterial thrombolysis. Cochrane Database of Systematic Reviews, 1. CD000985. Kommareddy, A., Zaroukian, M.H., & Hassouna, H.I. (2002). Upper extremity deep vein thrombosis. Seminars in Thrombosis and Hemostasis, 28(1), 89-99. Laiho, M.K., Oinonen, A., Sugano, N., Harjola, V.-P., Lehtola, A.L., & Roth, W.-D., et al. (2004). Preservation of venous valve function after catheter-directed and systemic thrombolysis for deep venous thrombosis. European Journal of Vascular and Endovascular Surgery, 28(4), 391-396. Mahon, B.R., Nesbit, G.M., Barnwell, S.L., Clark, W., Marotta, T.R., & Weill, A., et al. (2003). North American clinical experience with the EKOS MicroLysUS Infusion Catheter for the treatment of embolic stroke. ANJR American Journal of Neuroradiology, 24(3), 534-538. Mewissen, M.W., Seabrook, G.R., Meissner, M.H., Cynamon, J., Labropoulos, N., & Haughton, S.H. (1999). Catheter-directed
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thrombolysis of lower extremity deep venous thrombosis: Report of a national multicenter registry. Radiology, 211(1), 39-49. Murphy, K.D. (2004). Mechanical thrombectomy for DVT. Techniques in Vascular and Interventional Radiology, 7(2), 79-85. Ouriel, K. (2002). Current status of thrombolysis for peripheral arterial occlusive disease. Annals of Vascular Surgery, 16(6), 797-804. Ouriel, K., Veith, F.J., & Sasahara, A.A. (1998). A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. Thrombolysis or Peripheral Arterial Surgery (TOPAS) Investigators. New England Journal of Medicine, 338(16), 1105-1111. Raabe, R.A. (2006). Ultrasound-facilitated thrombolysis in treating DVT. Endovascular Today, 5(4), 75-79. Semba, C.P., Razavi, M.K., Kee, S.T., Sze, D.Y., & Dake, M.D. (2004). Thrombolysis for lower extremity deep venous thrombosis. Techniques in Vascular and Interventional Radiology, 7(2), 68-78. Sharafuddin, M.J., Shilian, S., Hoballah, J.J., Youness, F.M., Sharp, W.J., & Roh, B. (2003). Endovascular management of venous thrombotic and occlusive diseases of the lower extremities. Journal of Vascular and Interventional Radiology, 14(4), 405-423. Sieggreen, M. (2006). A contemporary approach to peripheral vascular disease. The Nurse Practitioner, 31(7), 14-25. Sullivan, K.L., Gardiner, G.A., Jr., Shapiro, M.J., Bonn, J., & Levin, D.C. (1989). Acceleration of thrombolysis with a highdose transthrombus bolus technique. Radiology, 173(3), 805-808. Working Party on Thrombolysis in the Management of Limb Ischemia. (2003). Thrombolysis in the management of lower limb peripheral arterial occlusiondA consensus document. Journal of Vascular and Interventional Radiology, 14(9 Pt 2), S337-S349.
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