As promised, Dr Santiago Chahwan of Anchors Vascular Surgery in Naples, Florida provides some personal insights from his experience with percutaneous treatment of acute Iliofemoral Deep Venous Thombosis (DVT)
Dr Chahwan: Despite evidence that patients with iliofemoral DVT suffer the worst postthrombotic sequelae, most patients continue to be treated with anticoagulation alone. While anticoagulation generally prevents thrombus propagation, it does not avoid chronic venous insufficiency and the postthrombotic syndrome.
In the current era of minimal intervention and endovascular technology this under appreciated disease spectrum I believed needs a paradigm shift in its treatment. A strategy of thrombus removal offers patients an opportunity for rapid resolution of symptoms, avoiding post-thrombotic morbidity. It makes intuitive sense that eliminating the acute thrombus leading to the persistent venous obstruction would benefit patients over the long term, and indeed it does. Furthermore, thrombus extraction not only eliminates venous obstruction but also preserves valvular function.
There is increasing evidence that thrombus removal or early thrombus resolution after acute DVT is associated with improved outcomes. Benefits of thrombus removal derive from data generated from experimental animal studies, findings from natural history studies of acute DVT treated with anticoagulation, venous thrombectomy data, and observations following systemic and catheter-directed thrombolysis supports the concept that thrombus removal in patients with acute iliofemoral DVT results in significantly less postthrombotic morbidity.
In order to build a succesful program the refering and emergency room physician should be educated about DVT and the importance of quick referal to the endovascular specialist as soon it is diagnosed. Several talks have been given also to the community to educate about this underdiagnosed disease.
In our institution we recommend that any DVT involving the femoral vein and above, with the presence of thrombus occluding at least more than 50 % of the luminal area, be considere for percutaneous intervention. If ileofemoral DVT , then CT of the chest, abdomen and pelvis is performed to identify the proximal extent of thrombus and to evaluate for abdominal or pelvic pathology . This has been an important addition to the evaluation of these patients, as we have found serious unsuspected pathology with surprising frequency. Renal cell carcinoma, adrenal tumors, retroperitoneal lymphoma, hepatic metastases, iliac vein aneurysms, and vena caval atresia all have been identified. A full hematologic evaluation for an underlying thrombophilia is also performed.
Technique
The preferred approach is through an ultrasound-guided popliteal vein puncture with antegrade passage of the infusion catheter. Through this approach physicians can incorporate adjunctive mechanical thrombectomy techniques. If the popliteal vein is thrombosed, an additional catheter is placed through an ultrasound-guided tibial vein puncture. Using catheters that achieve long segments of thrombus infusion is advised.Vena caval filters are not routinely used but are recommended for patients with free-floating thrombus in the vena cava. A retrievable filter can be used in the patient in whom only temporary protection is needed. Following successful thrombolysis, the venous system is examined with completion phlebography. Residual areas of stenosis must be corrected for long-term success with stents; otherwise, the patient faces a high risk of rethrombosis.
I use the segmental and controlled pharmacomechanical thrombolysis catheter from Bacchus Vascular, Santa Clara, CA, called the Trellis 8, which is a hybrid catheter that isolates the thrombosed vein segment between 2 occluding balloons, needs a 8 Fr sheet and a lytic agent is infused into the thrombus between the occluding balloons. The intervening catheter shaft assumes a sign wave or spiral configuration and, when activated, spins at 35,000 rpm. After 10-15 minutes, the liquified thrombus and remaining fragments are aspirated. One or two runs are ussualy necessary to succesful thrombus resolution. Phlebographic evaluation of the result is performed before moving on to treat additional thrombosed vein segments. After resolution of the thrombus, a phlebographic imagine is performed and any venous stenosis is corrected with an appropriate stent.
The advantages of the Trellis 8 device is its ability to incorporate mechanical and pharmacologic therapies, even in patients with a contraindication to thrombolytic therapy since the infusate is aspirated, and the rapidity with which treatment can be achieved. The rationales behind the design of this catheter are (1) rapidly resolve thrombus during a short course of treatment, (2) limit or avoid exposure to thrombolytic therapy by aspirating liquified thrombus and infused lytic agent, and (3) prevent PE by proximal balloon occlusion. Thrombolysis is effective and has become safer with the direct intrathrombus infusion and adjunctive mechanical techniques. As technology continues to improve, lytic infusion times will shorten, more patients will be offered a treatment strategy that includes thrombus removal, and many patients will be spared their otherwise certain postthrombotic morbidity.
