Treating Deep Vein Thrombosis
Devices, techniques, and side effects to keep in mind when treating DVT.
By Robert A. Lookstein, MD

PREPROCEDURAL TESTING
Duplex ultrasonography is used to make the initial diagnosis, followed by CT venography of the chest, abdomen, pelvis, and thighs to document the extent of clot and exclude any variant anatomy (duplicated inferior vena cava [IVC], congenital absence of IVC, azygos continuation of IVC). The CT scan can also identify a pre-existing IVC filter. Our center will not perform deep vein thrombosis (DVT) thrombectomy without a CT venogram to address these concerns before the procedure.

ACCESS SITES
The most common access is the popliteal vein from a posterior approach with the patient in the prone position. If there is extensive calf vein thrombus, consider the posterior tibial vein approach. Another site that can be used for isolated iliac vein thrombus is the ipsilateral common femoral vein. Our center does not routinely use a contralateral femoral vein or jugular approach for lower-extremity cases.

VENOUS ACCESS SITE EQUIPMENT
We use a 4-F or 5-F micropuncture kit, ultrasound for venous access, 6-F sheath for femoral DVT, and an 8-F sheath for iliac and caval thrombus.

• 4-F to 5-F, 100-cm hydrophilic catheter
• 4-F to 5-F, 100-cm calibrated flush catheter (pigtail or omni flush)

• .035-inch angled glidewire (180 and 260 cm)
• .035-inch Bentson wire (150 and 260 cm)
• .035-inch Amplatz superstiff (180 and 260 cm)

TECHNICAL NOTES FOR DIAGNOSTIC PORTION
Popliteal access can be difficult in an extremely swollen extremity. Use excellent ultrasound imaging to localize and visualize the popliteal vein during access. Avoid the popliteal artery at all costs. A popliteal artery hematoma can lead to compartment syndrome during the lysis portion of the procedure.

• .035-inch angled glidewire (180 and 260 cm)
• .035-inch Bentson wire (150 and 260 cm)
• .035-inch Amplatz superstiff (180 and 260 cm)

• 6-F, 10-cm sheath for isolated iliac DVT
• 8-F, 10-cm sheath for iliofemoral-popliteal DVT

MECHANICAL THROMBECTOMY DEVICES
Several devices are currently available. This author preferentially uses the AngioJet catheters (120-cm Expeedior and 90-cm DVX, Possis, Inc., Minneapolis, MN). A complete product listing of mechanical thrombectomy devices can be found on pages 137-140.

• 6-mm to 8-mm X 10-cm, low-pressure balloons for femoropopliteal DVT
• 10-mm to 12-mm X 6-mm to 8-cm, low-pressure balloons for iliac veins
• 18-mm X 4-cm, low-pressure balloons for IVC. Do not use high-pressure balloons in the iliac veins and IVC to avoid tear/rupture. Pelvic and retroperitoneal venous injuries are very difficult to manage in the setting of thrombolysis.

• 14-mm X 40-, 60-, 80-mm, self-expandable stents (nitinol) for May-Thurner lesion
• 18-mm to 20-mm X 68-mm Wallstent (Boston Scientific Corporation, Natick, MA) for IVC

We do not routinely stent below the inguinal ligament.

INTERVENTIONAL NOTES
Our center routinely performs power-pulse spray rapid pharmacomechanical thrombolysis for acute DVT. All procedures are performed with full heparinization usually initiated the day prior to intervention. All procedures are initiated in the morning to enable single-day therapy.

Protocol: 20-mg alteplase in 50 mL normal saline (for a total of 70 mL).

This thrombolytic is infused with the AngioJet catheter centrally to peripherally in one pass. During the infusion of the thrombolytic agent, the aspiration port of the AngioJet catheter is clamped with a flow switch to prevent aspirating the thrombolytic agent.

The pump drive is monitored during the infusion to calculate the appropriate time to pull back the catheter and infuse the entire bolus. The infusion is stopped after 60 to 65 mL of infusate is delivered. Do not let the infusate bag empty and let air into the pump drive. Wait 30 to 45 minutes for the alteplase to activate the clot (the longer the wait time, the better result). After the wait time, run the AngioJet in the normal mode (unclamp the flow switch from the aspiration port) to allow the thrombus to be aspirated by the catheter. After two full passes (one antegrade and one retrograde, which equals one full pass) perform repeat venography. Based on the appearance of the venogram, the operator can either (1) perform balloon maceration, (2) initiate catheter-directed thrombolysis, (3) perform directed mechanical thrombectomy with a curved 8-F guide catheter (Cobra/Hockey Stick/Multipurpose) to allow better wall apposition of the AngioJet catheter, or (4) perform a combination of all of these.

At our center, we routinely perform catheter-directed thrombolysis for 4 to 6 hours with low-dose alteplase (0.5 to 1 mg/h) to allow antegrade flow to debulk any adherent thrombus. During this period, the patient should have the affected limb elevated and have pneumatic compression stockings placed. The patient is then brought back to the interventional suite later in the day for aggressive wall-directed mechanical thrombectomy and balloon maceration. At this time, any resistant lesions can be stented. Once 90% to 100% clot lysis is achieved, the sheath can be removed and full anticoagulation can be initiated with low-molecular-weight heparin or warfarin. With this protocol, 75% of our cases can be treated in 1 day without the need for overnight intensive care monitoring.

Side Effects
Hemolysis. All patients are required to have Foley catheters placed the night before the procedure. Expect gross hematuria, especially with the DVX catheter. This is seen in almost all cases and is treated with aggressive hydration with sodium bicarbonate solution to alkalinize the urine and minimize the risk of renal tubular acidosis.

Patients need to be anticoagulated after the procedure in a manner similar to any patient with DVT (usually a minimum of 6 months). Patients are also worked up for hypercoagulable conditions and are treated appropriately. Clinical and imaging (usually ultrasound) follow-up is done at 3, 6, and 12 months.

Robert A. Lookstein, MD, is Assistant Professor of Radiology, Vascular Interventional Radiology, Mount Sinai Medical Center, New York, New York. He has disclosed that he is a paid consultant to Possis. Dr. Lookstein may be reached at (212) 241-7409; robert.lookstein@mountsinai.org.