Endovascular treatment of acute proximal deep venous thrombosis secondary to iliac vein compression syndrome: a novel technique for thrombus removal.

Iliac vein compression syndrome (IVCS), also known as May-Thurner syndrome or Cockett syndrome, is caused by compression of the left common iliac vein between the right common iliac artery and the vertebrae. A recent imaging study have demonstrated that at least a 25% compression of the left iliac vein at the arterial crossover point may be present in 66% of the asymptomatic patient population.1 With the development of interventional technique, endovascular management as a less invasive means is becoming the first-line treatment, which can not only treat the thrombosis but also correct the venous anatomic abnormalities.2 In this study, we described a novel technique combining percutaneous aspiration thrombectomy (PAT) with Fogarty catheter thrombectomy (FCT) as the thrombus removal therapy without femoral venotomy in patients with acute deep vein thrombosis (DVT) due to IVCS and evaluated its technical feasibility and short-term outcomes. METHODS Patients Between October 2008 and December 2011, 28 limbs in 28 consecutive patients with acute (1-14 days) left DVT secondary to IVCS were treated with endovascular methods (Table 1). Diagnosis of DVT was established using color Doppler ultrasonography (CDUS) and iliac vein stenosis was confirmed by venography during endovascular treatment in all patients. No inferior vena cava (IVC) was involved. The exclusion criteria were contraindications to administration of iodinated contrast media, malignancy with a short survival expectancy, and the presence of concurrent acute and chronic DVT in the treated extremity. All patients received endovascular therapy on the same or next day following their presentation to our hospital.Table 1: Patient characteristics (n=28)Procedures All procedures were performed in an angiography suite using digital subtraction angiography (Angiostar, Siemens, Germany or Allura Xper FD20, Philips Healthcare, Holland). Patients were placed in the supine position, and an ascending venogram was obtained from the dorsalis pedis vein to observe the extent and location of thrombosis. Anticoagulation was carried out with an initial intravenous bolus of 3000-5000 U heparin, which was then continuously infused at a rate of 1000 U/h. In view of the risk of pulmonary embolism while performing thrombus aspiration, we placed the inferior vena cava filter (IVCF) prophylactically in all patients. A retrievable/permanent IVCF was advanced via the contralateral common femoral vein to the infrarenal IVC and placed at 5-10 mm below the lowest side of renal vein. After placement of IVCF, aspiration thrombectomy was performed via the ipsilateral common femoral venous approach. An 8F vascular sheath was inserted into the contralateral common femoral vein, then the ipsilateral common femoral vein was punctured directly under ultrasound guidance. An 8F vascular sheath was inserted to obtain a diagnostic venogram to assess the patency of iliac veins. Then, a 14F vascular sheath (Stent Vena Caval and Venous Design Radiopapue Band Introducer Set, Cook, Denmark) was exchanged to the thrombosed iliac vein and advanced over a guide wire to prevent venous injury (Figure 1A). Aspirations were performed from the cranial to caudal ends after withdrawing the dilator and guide wire (Figure 1B). The entrance of the vascular sheath was pressed with right index finger to prevent leakage, and the thrombi were gently aspirated using a 50 ml syringe to maintain negative pressure during the withdrawal of the large-lumen sheath. The guide wire was introduced to IVC again before the 14F sheath was removed outside of the vein. Then, by withdrawing the sheath outside of the body, the dilator can be rinsed and reinserted into the sheath. Aspiration thrombectomy was repeated by advancing and withdrawing the large-lumen sheath in the thrombus-filled common and external iliac vein until all thrombi were macerated and aspirated. As for femoropopliteal venous thrombus, a 7F “crosses sheath” (Flexor Up Over Balkin Contralateral, Cook, USA) was inserted from the contralateral common femoral vein into the ipsilateral common femoral vein over a guide wire (Figure 1E and 1F). If there was resistance when advancing the guide wire to the cavity of 14F sheath (“threading” technique; Figure 1C) and the working wire pathway could not be established to insert “crosses sheath,” an improvized snare kit was introduced to pull wire from IVC to contralateral vein (Figure 1D), after which a 6F wire-guided Fogarty balloon catheter (Fogarty, Edwards Lifesciences, USA) was inserted via the “crosses sheath” into a thrombus-filled femoropopliteal vein. The Fogarty balloon was gently inflated using contrast and withdrawn by applying adequate pressure to pull thrombus from the iliac vein (Figure 1H and 1I). Then, aspiration thrombectomy was performed again (Figure 1J). After removal of thrombi from the proximal veins, additional venograms were obtained during the procedure for detailed evaluation of the iliac vein and IVC. If there was significant stenosis (>50% luminal narrowing) or residual thrombi that could not be removed from the iliac vein, self-expanding stents (E-Luminexx, Bard, Germany) were placed and dilated with a balloon catheter to increase the flow into the proximal vein. CDT was used to dissolve the thrombus in the calf veins in selected patients or to dissolve the residual thrombus in the femoral and iliac veins. Contralateral common femoral artery was accessed, and an infusion catheter was inserted into the ipsilateral superficial femoral artery. Urokinase at a dose of (60-80)×104 U/d was used as the thrombolytic drug for 3-5 days. After the intervention, all patients were fully anticoagulated using standard heparin for 24 hours and was subsequently replaced by low-molecular-weight heparin and oral warfarin. The dose of warfarin was adjusted to achieve an international normalized ratio of 2-3 for 6 months.Figure 1.: The main procedure of PAT combined with FCT. “Threading” technique was first used (C) and then “capturing” technique was used as second choice after an unsuccessful attempt (D).Definition of criteria Removal of the thrombus was scaled as minimal (grade I) if <50% was removed; partial (grade II) if 50%-95% was removed; and complete (grade III) if >95% of the thrombus was removed. Technical success was defined as more than 50% clot removal with uninterrupted venous flow. All patients were followed up by clinical examination at 3, 6, and 12 months after the procedure. The patency of the veins was determined using venography or CDUS. The severity of post-thrombotic syndrome (PTS) was classified according to the Villalta PTS scale. RESULTS The technical success rate of the thrombectomy procedure was 100% (28/28). Twenty-five patients received retrievable filters (Aedis, Lifetech, China) and three received permanent filters (SNF/SL, Bard, Germany). All retrievable IVCFs were removed successfully within 7 days. Thrombus removal was complete (grade III) in 23 limbs (82.1%), partial (grade II) in five limbs (17.9%), and minimal (grade I) in none of the limbs (0%) on venography. CDT was used in 16 patients (57.1%) as an adjunctive treatment following PAT. The mean dose of the urokinase was (237±50)×104 U. All patients with common/ external iliac vein stenosis underwent stent implantation successfully. The stent diameters ranged from 12 to 16 mm. The mean hospitalization duration was (5.3±1.2) days. No treatment failure occurred in this cohort. Minor bleeding episodes related to thrombolysis occurred at the vein access site in two patients, and hemorrhage was stopped without any consequence by press on the access site for 10 minutes. Clinical follow-up was available for all patients for mean 11 months (ranging from 6 to 12 months). Twenty-three (82.1%) of the 28 patients were asymptomatic during the follow-up period. Rethrombosis occurred in five patients and the stent was obstructed again in two patients. Reinterventions were performed in four of the five patients, with successful restoration of the venous flow in four patients. Twenty-four patients had no PTS during the follow-up period. Three mild and one moderate PTS were present in patients with Grade II thrombus removal at 1 year after the procedure. DISCUSSION The present study showed that aspiration thrombectomy combined with Fogarty balloon catheter can be safely and effectively used for the treatment of acute massive proximal DVT secondary to IVCS. The advantages of thrombus aspiration treatment are lower cost, simpleness, and practical utility. The drawback is that clot removal is rarely complete, especially the large thrombus is difficult to remove when using sheath or catheter smaller than 10F. In this study, we improved the technique of surgical embolectomy using Fogarty catheter to drag thrombi from popliteal vein to a more centralized location (iliac vein). Then, a large cavity sheath (14F) was inserted through the femoral vein without surgical incision to aspirate and these thrombi were removed. It is worth noting that thrombus removal of grade III was achieved in up to 82.1% of the limbs in the present study. The first keypoint of this procedure was inserting a “crosses sheath” to provide adequate support for the Fogarty balloon catheter to extract thrombus from the distal vein. Generally, it is very difficult to introduce the “crosses sheath” because of the presence of severe stenosis or obstruction in the iliac vein. Thus, it is necessary to establish a pathway of “contralateral-ipsilateral femoral vein guidewire track,” which is the second keypoint of the procedure. The most common snare device is GooseNeck Snare Kit, but its price is relatively expensive. We designed a novel easy-making snare apparatus by inserting an angled hydrophilic guide wire into a 4F catheter, binding the wire tip on the outer wall of the catheter tip with common surgical suture, and keeping the suture longer than the catheter so that it can be dragged out in case of suture loosening. This improvized snare apparatus can be conveniently used and the ring size can be adjusted according to the vein diameter. In the current study, although the stenosis of iliac vein may in part prevent thrombus flowing into IVC,3 we placed IVCFs in all patients to prevent pulmonary artery embolization during procedures. The preoperative PE was present in two patients at admission in our study, and no additional PE occurred after endovascular procedure. In conclusion, PAT combined with FCT is a safe and effective endovascular therapy for acute proximal DVT secondary to IVCS. It has the major advantage of rapid thrombus removal without surgical femoral venotomy and reduced bleeding complications.