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Catheter-Directed Treatment of Lower-Extremity DVT Reliable relief of acute symptoms is achievable via this endovascular technique. By Bulent Arslan, MD; Ulku C. Turba, MD; John F. Angle, MD; And Alan H. Matsumoto, MD Deep venous thrombosis (DVT), even in the absence of associated pulmonary embolism (PE), can result in significant morbidity. Primary symptoms associated with acute lower-extremity DVT are pain and swelling, which can be debilitating. Venous valvular damage and venous insufficiency can occur as sequelae of DVT and lead to chronic ambulatory venous hypertension and symptoms related to the postthrombotic syndrome (PTS). Traditional treatment of acute DVT is long-term anticoagulation and the use of compression stockings. This is the most common treatment, particularly for minimally symptomatic femoropopliteal thrombosis. However, in patients with acute iliofemoral thrombosis and persistent or progressive symptoms, there is evidence to suggest that catheter-directed treatment (CDT) options may provide both clinical and hemodynamic benefits.1,2 There is also some evidence that CDT may be more effective in preventing morbidity related to the PTS when compared to anticoagulation alone in the treatment of acute iliofemoral DVT.3,4 DIAGNOSIS Ultrasound (US) is the most commonly used diagnostic modality in the evaluation for acute DVT. US is accurate and also cost efficient. MR and CT venography can provide more information regarding the extent of involvement of the pelvic veins and inferior vena cava (IVC). These modalities can also define the location of an existing IVC filter and whether or not the thrombus involves the filter. A CT pulmonary angiography, which can be performed at the same time with the CT venography, can also demonstrate any existing pulmonary thromboembolism. On occasion, conventional venography may be necessary to help differentiate between acute and chronic thrombus and define the total extent of venous thrombosis. Use of additional imaging tests beyond US will depend on the specific clinical concerns associated with each case. ACCESS In most cases of acute iliofemoral DVT in which CDT is planned, ipsilateral antegrade popliteal venous access is used. If bilateral DVT is present, then bilateral popliteal venous access is obtained. Some cases require use of an internal jugular venous access, especially if a prophylactic retrievable IVC filter is placed (GŸnther Tulip or Celect, Cook Medical, Bloomington, IN; OptEase, Cordis Corporation, Warren, NJ; G2, Bard Peripheral Vascular, Tempe, AZ). If the interventionist would like to avoid internal jugular access, a retrievable filter can also be placed through the popliteal access using a longer-length alternate sheath instead of the regular sheath that comes with the filter kit. Although rare, there are reported cases of catastrophic PE during CDT for acute DVT.5 Given the availability of retrievable IVC filters, if an IVC filter is not already in place, we have adopted the algorithm of placement of a prophylactic retrievable IVC filter in almost all of our cases of CDT for acute iliofemoral or iliocaval DVT. Initial venous access is always obtained using US guidance with a 21-gauge micropuncture needle set (Cook Medical; AngioDynamics, Inc., Queensbury, NY) to minimize the risk of an inadvertent arterial puncture or multiple venous punctures. Meticulous technique for vascular access is critical because the patient will be receiving a thrombolytic agent, and bleeding complications need to be minimized. Usually, a 6-F to 8-F sheath is placed in each access site if mechanical thrombectomy is planned. Catheter-directed infusion therapy of a thrombolytic agent (rtPA or tenecteplase, urokinase, retaplase) can be performed via a 4-F or 5-F sheath; however, most cases of iliofemoral DVT will benefit from use of adjunctive pharmacomechanical thrombectomy, balloon angioplasty, and/or stenting to facilitate more rapid venous recanalization. We prefer a reinforced short (11 cm) Arrow (Arrow International, a Division of Teleflex Medical, Reading, PA) or Flexor (Cook Medical) sheath due to their kink resistance. Because the popliteal vein is relatively deep in a swollen leg, bending the knee may cause kinking of a nonreinforced sheath, which may result in occlusion of an infusion catheter and/or oozing of blood at the access site. The sheath size should be chosen to accommodate the planned thrombectomy device(s). WIRES AND CATHETERS After placing the sheath over a standard J wire (Cook Medical, AngioDynamics, Inc., and others) or a Wholey wire (Covidien, Hazelwood, MO), an angled catheter (Kumpe, Bernstein, multipurpose, or vertebral shape) is advanced over the wire to the IVC above the level of thrombus. If there are occlusive segments that are difficult to traverse due to chronic thrombus and/or extrinsic venous compression, a hydrophilic angled nitinol guidewire, such as the Glidewire (Terumo Interventional Systems, Somerset, NJ), may be helpful to traverse the occluded segments. Once the catheter is above the thrombus, an appropriate exchange-length wire, such as the Amplatz (extra stiff, Cook Medical; or super stiff, Boston Scientific Corporation, Natick, MA), Rosen (Cook Medical, AngioDynamics, Inc.), or Wholey wire will provide enough support to allow advancement and positioning of the mechanical thrombectomy devices. Of note, when advancing the catheter and wire cephalad to the popliteal vein, the need to treat duplicated superficial femoral veins should be considered, as they are seen in ≤30% of patients. THROMBECTOMY DEVICES To facilitate thrombolysis, we commonly perform mechanical thrombectomy during the initial access procedure, usually in conjunction with thrombolytics. There are many devices available, but we have found the following devices particularly useful for dealing with the large size of the iliac veins and the large volume of thrombus to be treated. AngioJet The AngioJet device (Possis Medical, Minneapolis, MN) requires a minimum of a 6-F sheath or an 8-F guide catheter for peripheral venous applications. It uses powerful jets and relies on the Bernoulli principle to remove thrombus. The power-pulse spray technique with this device involves closing off the effluent port on the device so that the thrombolytic agent solution (ie, 5-20 mg rtPA dissolved in 50-100 mL of normal saline) is dispersed as a high-velocity spray throughout the length of the thrombus and allowed to dwell for 20 to 30 minutes followed by use of the AngioJet in the standard fashion over the same venous segments. This technique has been shown to facilitate thrombus breakdown and shorten the total procedure time.6 The Possis Xpeedior (120 cm long) catheter is approved for use with the power-pulse spray technique by the FDA. The Possis DVX (90 cm long) catheter has five times greater power; therefore, it may be more effective in decreasing the thrombus burden but probably creates more hemolysis, especially using the power-pulse spray technique. Trellis The Trellis device (Bacchus Vascular, Santa Clara, CA) requires a minimum of an 8-F sheath. The catheter has four lumina: one to inflate the proximal balloon, one to inflate the distal balloon, one for the guidewire, and one that allows infusion and aspiration of the segment of vein between the two inflated balloons. When the catheter is connected to its power source, the catheter segment between the two inflated balloons precesses along the long access of the catheter in a sinusoidal pattern. The isolated venous segment (either 15 or 30 cm) is infused with a thrombolytic agent (ie, 4 to 6 mg rtPA), and then the Trellis catheter is turned on, creating a pharmacomechanical disruption of thrombus within the isolated venous segment. The macerated thrombus is aspirated while both balloons are inflated and, in theory, minimizes the risk of thrombus embolization and systemic distribution of the thrombolytic agent. The Trellis device will be incorporated into the ATTRACT (Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis) trial, which is an NIH-funded trial to assess if CDT can prevent PTS with an acceptable risk in patients with acute proximal DVT. Trerotola The over-the-wire version of the Trerotola device (Arrow) requires the use of a 7-F sheath and is used in veins in an off-label application. On occasion, we have used this device to fragment resistant thrombus within the iliac vein or IVC. The device can be problematic below the inguinal ligament, as it has the potential of grabbing the valves within the femoral or popliteal veins. MULTISIDEHOLE INFUSION CATHETERS Cragg-McNamara The 4-F and 5-F Cragg-McNamara (ev3 Inc., Plymouth, MN) catheters are available with infusion lengths of 5, 10, 20, 30, 40, and 50 cm. Catheter lengths are available between 40 and 135 cm. MicroMewissen The MicroMewissen (ev3) catheters are available in 2.5-F sizes with infusion lengths of 5 and 10 cm and a total length of 150 cm. Unifuse The Unifuse (AngioDynamics, Inc.) catheters are available in a 5-F size with infusion lengths of 5, 10, 20, 30, 40, and 50 cm. The 4-F Unifuse catheters are available with infusion lengths of 5, 10, and 20 cm. The Unifuse catheters incorporate the use of a tip occluding wire. EKOS Endowave Peripheral Infusion System The EKOS Endowave Peripheral Infusion System (EKOS Corporation Bothell, WA) combines the use of a 5-F multisidehole infusion catheter (12-, 18-, 24-, 30-, 40-, and 50-cm infusion lengths) and a high-frequency, low-power US to facilitate distribution of the thrombolytic agent into the interstices of the thrombus and perhaps break fibrin bonds. It is based on the theory of US waves temporarily loosening the fibrin components, allowing more surface contact with the thrombolytic agent. The 5-F infusion catheter uses a standard .035-inch guidewire that is replaced by the US wire after positioning of the catheter at the desired location. The US wire is activated during the infusion of the desired thrombolytic agent. STENTS Once thrombolysis is complete or becomes static, we often use stents above the inguinal ligament for areas of persistent narrowing. We reserve stents for sites of extrinsic compression or intrinsic narrowing not due to acute thrombus. These devices are used in an off-label application for venous disease. Nitinol Stents Nitinol stents (Protégé, ev3; Smart, Cordis) are self-expanding and foreshorten minimally upon expansion. Nitinol stents are MR compatible. A multitude of brands of nitinol stents can be used; however, the most frequent diameters used in the iliac vein are 8, 10, 12, and 14 mm. A large variety of companies sell nitinol stents 10 mm or smaller in diameter. Wallstent The Wallstent (Boston Scientific) is not nitinol; it is made of an MR-compatible alloy called elgiloy. It comes in diameters larger than currently available nitinol stents. These stents are available in 16-, 18-, 20-, 22-, and 24-mm diameters, in addition to smaller diameters. These stents are self-expanding but do foreshorten a fair amount, in an asymmetric fashion. Large Palmaz The Large Palmaz stent (Cordis) is made of 316L stainless steel and therefore creates MR susceptibility artifacts. The large Palmaz stent is hand-mounted onto a balloon of the desired diameter and is balloon expanded. Its diameter can be dilated from 10 to 28 mm. The stent foreshortens a varying amount, depending on its expanded diameter. BALLOONS A variety of angioplasty balloons from different companies can be used to perform venous angioplasty or to further dilate stents. Abbott Vascular (Santa Clara, CA), Bard Peripheral Vascular, Cook Medical, Cordis, B. Braun (Bethlehem, PA), and Boston Scientific are manufacturers that make balloons larger than 10 mm. An abundance of companies make balloons smaller than 10 mm in diameter  Tips & Tricks: Complication Avoidance in DVT Therapy The patient is ultimately placed in a prone position, the popliteal vein in the symptomatic leg is accessed in an antegrade fashion using US guidance, and the appropriate-size sheath is placed. In most cases, the AngioJet device is used, and the power-pulse spray technique is employed. If the Trellis device is chosen, it is used in overlapping treatment zones throughout the thrombosed segment of vein. After performing pharmacomechanical thrombectomy, the venous segments with residual thrombus are treated with catheter-directed thrombolysis using a multisidehole infusion catheter. Some interventionists prefer to perform CDT using the EKOS infusion catheter system. The patients are observed in an intermediate care unit or an ICU. The patient is re-evaluated in 8- to 24-hour increments depending on the time of day, concerns for bleeding, clinical symptoms, and other pragmatic variables. If residual thrombus is identified, further mechanical thrombectomy with or without thrombolytic agents is performed until the majority (>90%) of thrombus is removed and there is good antegrade flow. If necessary, catheter-directed thrombolysis is continued to thrombolyse the residual thrombus, and the process is repeated. Once the majority or all the acute thrombus is removed and good antegrade flow is established, the underlying stenoses and/or occlusions due to chronic thrombus or extrinsic compression are treated. We routinely attempt balloon angioplasty for chronic thrombus or residual synechiae but will place a stent if the angioplasty result is suboptimal. However, in cases of extrinsic venous compression due to May-Thurner syndrome, malignancies, or adenopathy, primary stent placement is performed. We prefer to use self-expanding stents in the iliac veins. For IVC stenoses or occlusions, if the underlying pathology directly involves a pre-existing IVC filter, we use a Palmaz stent (Cordis) to push the filter to one side to re-establish an adequate lumen. In the absence of an IVC filter, larger self-expanding stents are preferred for treatment of stenosis or occlusions involving the IVC. Even with complete thrombolysis, we recommend long-term anticoagulation for 3 to 6 months. If a prophylactic IVC filter was placed, we remove the filter prior to starting coumadin. If clinically indicated, patients undergo a hypercoagulable state evaluation by a hematologist. If a hypercoagulable problem is identified, the hematologist may choose to place the patient on anticoagulants for life. If there is a hereditary component, family evaluation is also undertaken. If no identifiable hypercoagulable state is detected, after 3 to 6 months of full anticoagulation, the anticoagulation is stopped. If the patient had stents placed, an additional 3 to 6 months of clopidogrel 75 mg/d and aspirin 80 to 325 mg/d are prescribed. After this time period, aspirin is recommended for life. US follow-up is also performed at 6 weeks, 6 months, and 1 year, as well at any time the patient's symptoms recur. On occasion, it may be necessary to perform MR or CT venography to evaluate the pelvic veins and IVC. Potential Complications Hemolysis is very common with use of the AngioJet thrombectomy device. Placement of a Foley catheter in every patient is therefore essential to monitor urine output and to minimize the need to use a bedpan. We routinely hydrate our patients with sodium bicarbonate, with the added benefit of alkalinizing the urine to facilitate free hemoglobin excretion by the kidneys. Rare cases of renal failure have been reported with use of the AngioJet thrombectomy, possibly related to the hemolysis, in combination with the nephrotoxicity of iodinated contrast. Bleeding and hematomas can be minimized by meticulous vascular access, minimizing venipunctures for blood, and maximizing patient bedrest. There remains debate over the appropriate dosing of anticoagulants, such as heparin, during the thrombolysis because there is a risk of bleeding complications. Also, concomitant use of antiplatelet agents and coumadin should be minimized. Antacids or H-2 blockers should also be used to minimize the occurrence of bleeding associated with stress gastritis. SUMMARY Aggressive use of endovascular techniques for iliofemoral DVT can provide near-complete thrombolysis with reliable relief of acute symptoms and may help prevent the long-term sequelae of DVT that occurs when treated with anticoagulation alone. The aforementioned tools may help to facilitate this process. Bulent Arslan, MD, is from the Department of Radiology, Division of Angiography and Interventional Radiology at the University of Virginia Health System in Charlottesville, Virginia. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Arslan may be reached at (434) 924-9391; ba6e@hscmail.mcc.virginia.edu. Ulku C. Turba, MD, is from the Department of Radiology, Division of Angiography and Interventional Radiology at the University of Virginia Health System in Charlottesville, Virginia. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Turba may be reached at (434) 924-9391; uct5d@virginia.edu. John F. Angle, MD, is from the Department of Radiology, Division of Angiography and Interventional Radiology at the University of Virginia Health System in Charlottesville, Virginia. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Angle may be reached at (434) 924-9401; jfa3h@virginia.edu. Alan H. Matsumoto, MD, is from the Department of Radiology, Division of Angiography and Interventional Radiology at the University of Virginia Health System in Charlottesville, Virginia. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Matsumoto may be reached at (434) 924-9279; ahm4d@virginia.edu. |
