Version May 2024
INTRODUCTION — Iliocaval venous obstruction (ICVO) is an underrecognized venous outflow condition that can present with clinical features of chronic venous hypertension and chronic venous insufficiency, or with acute venous occlusion typically leading to extensive deep vein thrombosis (DVT).
Advancements in endovascular techniques have revolutionized the options for treating ICVO and are reviewed here. Whether to proceed with treatment depends upon the etiology of obstruction, severity of symptoms, and the presence or absence of thrombus (ie, thrombotic versus nonthrombotic ICVO). The clinical features, diagnosis, and approach to management of IVCO are reviewed separately [1]. (See "Overview of iliocaval venous obstruction".)
PROCEDURE OVERVIEW — Endovascular procedures used to treat iliocaval venous obstruction (ICVO) are typically performed in an interventional suite (eg, radiology, cardiovascular) or hybrid operating room using monitored conscious sedation. More advanced anesthetic techniques may be appropriate in selected cases. (See "Considerations for non-operating room anesthesia (NORA)", section on 'Vascular procedures'.)
Intervention for ICVO is undertaken in a stepwise fashion, including:
●Gaining initial access to the venous circulation. (See 'Potential sites for vein cannulation' below.)
●Performing initial venography to confirm the level and location of venous obstruction and also to define the presence and the extent of any thrombus. Although the patient is likely to have had a venous duplex ultrasound (VDU) that identified a high likelihood of thrombus, the ability to fully characterize the obstruction with VDU can be limited due to a variety of factors (eg, body habitus, vein depth, overlying bowel gas). (See 'Procedural imaging' below.)
●Administering intravenous heparin for any identified thrombus or stenosis (weight-based dosing: 50 units/kg; partial thromboplastin time [PTT] target 1.5 to 2 times the upper limit of normal). For heparin allergy, alternative parenteral anticoagulants (eg, argatroban, bivalirudin) can be used. (See "Heparin and LMW heparin: Dosing and adverse effects" and "Management of heparin-induced thrombocytopenia (HIT) during cardiac or vascular surgery".)
●Reducing the burden of thrombus from the venous system, typically using a combined approach with pharmacologic thrombolysis and mechanical thrombectomy (ie, pharmacomechanical thrombolysis). (See 'Options for reducing thrombus burden' below.)
●Using intravascular ultrasound (ideal if available) to confirm and characterize the degree of stenosis and for determining measurements for stent placement. (See 'Procedural imaging' below.)
●Performing angioplasty/stenting of stenotic venous lesions and completion venography to confirm unobstructed venous patency and optimal stent positioning. (See 'Angioplasty/stenting' below and 'Procedural imaging' below.)
Vascular access is generally via the right or left common femoral vein and/or right internal jugular vein. A venogram showing the inferior vena cava (IVC) and both common iliac veins is obtained to locate and calibrate the area(s) of stenosis/occlusion. Intravascular ultrasound (IVUS) should be part of routine intraoperative assessment of any iliocaval pathology to precisely evaluate the proximal and distal extent of stenosis, to determine the actual diameter of the vessels, and finally to evaluate for any filling defects. Once the lesion is crossed with wire, the pressure gradient across the stenosis can be obtained (≥4 mmHg is significant in the IVC, >2 mmHg is significant in the iliac veins).
Balloon angioplasty is performed using a noncompliant balloon (eg, 6 x 40 mm) prior to angioplasty to facilitate stent placement, typically with stainless steel stents (eg, Gianturco Z stent, Wallstent, Venovo, balloon expandable Palmaz stent).
Post-stent ballooning is carefully performed to achieve proper iliocaval venous dilation. The balloon is undersized and slowly inflated. Overdilation or rapid inflation can cause caval rupture. Following stenting, a completion venogram as well as IVUS exam confirms adequate angioplasty/stenting and rules out any extravasation or venous webbing.
Following venous stenting, dual antiplatelet therapy (aspirin 81 mg and clopidogrel 75 mg daily) is maintained for 12 weeks, thereafter aspirin 81 mg each day is continued indefinitely.
TIMING OF TREATMENT — The severity of symptoms is the primary driver for intervention. (See "Overview of iliocaval venous obstruction", section on 'Approach to venous intervention'.)
For thrombotic iliocaval venous obstruction (ICVO), while most studies of the efficacy of thrombolytic therapy have used ≤14 days as a limit for treating acute thrombus [2-11], duration of symptoms, rather than the documented duration of thrombosis, is probably more important. In many interventional practices, clinicians intervene for thrombotic venous obstruction for several weeks from the onset of acute symptoms. We agree with guidelines from the Society for Vascular Surgery that state "on balance, recommendations for consideration of early thrombus removal strategies in patients with symptoms of <14 days of duration would seem fairly secure, although a benefit in patients with a duration of symptoms of >14 days cannot be excluded" [2]. Some clinicians may elect to pursue thrombolysis in selected patients even after several months if symptoms are severe and risks are judged to be low (eg, young, otherwise healthy patient with minimal risk of bleeding). The outcomes of treatment of longer duration thrombus and chronic venous disease (eg, post-thrombotic syndrome) are not as good as those for treatment of more acute disease. (See 'Outcomes' below.)
POTENTIAL SITES FOR VEIN CANNULATION — The approach to vein cannulation is made on a case-by-case basis and depends, in part, upon the extent of thrombus, if present, and the potential location of the stenotic venous lesion(s). The clinician needs to decide among the potential sites for vein cannulation and whether to approach ipsilateral or contralateral (ie, up-and-on over) to the clinically affected side. Routine real-time ultrasound-guided venous access is recommended during vein cannulation because it improves time to access and reduces the number of unsuccessful attempts and inadvertent arterial puncture, which are particularly relevant for reducing complications related to administration of pharmacologic thrombolytic agents (eg, hematoma). (See "Basic principles of ultrasound-guided venous access".)
●If the diseased segment is located in the inferior vena cava (IVC) or iliac veins, we generally approach from the groin. This includes thrombotic or nonthrombotic conditions. (See 'Femoral approach' below.)
●If the diseased segment includes the iliocaval segment and common femoral veins with or without femoropopliteal thrombus, we generally approach from the ipsilateral popliteal region, or possibly tibial region depending upon the extent of thrombus. However, a contralateral approach may be considered for achieving an unobstructed pathway from proximal to distal (cranial to caudal) in cases of extensive thrombosis. (See 'Popliteal approach' below.)
For patients with acute thrombus, a thrombolysis catheter can be placed to initiate thrombolytic therapy. For chronic iliocaval occlusion or following thrombolysis that reveals a persistent stenotic segment, the access sheath(s) will need to be "upsized" to a larger size (eg, up to 12 Fr sheath) to accommodate the necessary devices, balloons, and stents. (See 'Options for reducing thrombus burden' below and 'Angioplasty/stenting' below.)
Femoral approach — For iliocaval venous obstruction (ICVO) proximal (cranial) to the inguinal ligament, we position the patient supine. Both groins are prepared and draped in standard surgical fashion. Using ultrasound guidance, the common femoral veins are accessed bilaterally using a micropuncture kit, preferably at the saphenofemoral junction. The micropuncture sheath is upsized to an 8 Fr sheath and the patient is anticoagulated (eg, unfractionated heparin; 50 units/kg).
Bilateral iliac venograms are obtained using both anteroposterior and oblique views to evaluate the iliocaval segment. A glidewire is introduced through a guiding catheter to navigate through the iliocaval segment. Stiff-straight or stiff-angled glidewires may be needed. After confirming that the wire is in a segment of the inferior vena cava that is free from thrombus or stenosis, the glidewire is exchanged for a stiff, working wire (eg, Supracore).
Popliteal approach — For ICVO that involves the common femoral vein(s), with or without thrombosis, we generally position the patient prone to access the popliteal vein(s) or possibly tibial vein(s). Alternatively, if the contralateral iliofemoral veins are not involved, an up-and-over groin approach can be used. (See 'Femoral approach' above.)
The popliteal fossae bilaterally are prepared and draped in standard fashion. The popliteal vein ipsilateral to the diseased iliac segment is accessed using a micropuncture technique with ultrasound guidance. The micropuncture sheath is upgraded to a 5 or 6 Fr sheath and the patient is anticoagulated (eg, unfractionated heparin; 50 units/kg). A glidewire can be used to navigate through the occluded segments of the femoral, common femoral, and iliac veins, and inferior vena cava. After crossing all occluded segments, the intraluminal position of the wire is confirmed on venogram.
PROCEDURAL IMAGING — Once venous access is achieved, venography with adjunctive intravascular ultrasound (IVUS) is used to confirm the diagnosis of iliocaval venous obstruction (ICVO), aid in positioning devices, measure the vein to ensure proper stent sizing, and evaluate the results of intervention.
Venography — Contrast venography, particularly with the added use of transvenous pressure measurements, confirms the preintervention ultrasound diagnosis of ICVO and provides insight toward chronicity of lesions. Chronic lesions will be resistant to balloon angioplasty. Venography also identifies any variations, such as a duplicated or rudimentary venous system (figure 1).
Venography for caval lesions can be performed with a pigtail catheter using a pressure injector (600 psi) to bolus intravenous contrast (eg, Visipaque). Obtaining two or three different projections with a pigtail catheter in the external iliac vein may improve the accuracy of venography. However, for more distal (caudal) lesions, it may be equally effective to perform hand-injected venography through the access sheath in the femoral position rather than using a power injector.
Obtaining invasive hemodynamic pressure measurements is a valuable adjunct for confirming iliocaval venous stenosis. Simultaneous pressure measurements from both iliac veins can be obtained and compared. A pressure gradient of >2 mmHg can be used to diagnose significant stenosis [12]. Using a pullback method comparing the pressure in the inferior vena cava above the obstruction site with the pressure below the obstruction may be more accurate [13].
Intravascular ultrasound — IVUS, if available, can be performed after the initial venography. A high-frequency ultrasound transducer located directly on the tip of a catheter provides the operator with a real-time, cross-sectional image that can be used to examine the target vessel. Since its inception and with increasing use over the last decade, IVUS has become the single most important advancement in the evaluation and treatment of ICVO [14]. IVUS has become integral to stent deployment by providing accurate diameters for diseased and undiseased segments and for assessing any residual post-stenting stenosis. IVUS can also be used to locate the lowest renal vein during deployment of stents in the inferior vena cava or to estimate the degree of recanalization in those with post-thrombotic syndrome.
Several IVUS devices are available that vary in the type of transducer or catheter. For the iliocaval segment, a relatively "low" frequency catheter ultrasound transducer provides an acceptable balance between tissue penetration and high resolution. Several catheters are available for iliocaval imaging that use a 0.035 inch wire platform (eg, Volcano [60 mm, 10 MHz], Opticross [30 mm, 15 MHz], Sonicath [50 mm, 9 MHz]).
After initiating systemic anticoagulation with unfractionated heparin, the IVUS catheter is introduced through an 8 Fr sheath and connected to the intravascular ultrasound system (eg, Volcano S5).
IVUS should ideally be performed from both groin access locations to assess the iliac veins bilaterally. The orientation of intravascular ultrasound should be adjusted to identify the overlying iliac arteries. A slow pullback technique will precisely record the degree, extent, and nature of stenosis/thrombosis.
THROMBOLYSIS — Advancements in endovenous treatments have been instrumental in improving outcomes, particularly among those with thrombotic iliocaval venous obstruction (ICVO) [15]. A well-balanced discussion with the patient prior to intervention is important to convey the benefits/risks of treatment. The patient must understand all risks, including the risk of bleeding, compared with the potential benefit of a decreased chance of post-thrombotic syndrome.
Options for reducing thrombus burden — One or a combination of endovascular techniques can be used to reduce the burden of thrombus when it is encountered [2,16-25]. Available options include catheter-directed thrombolysis (CDT), mechanical thrombectomy, or a combination (ie, pharmacomechanical thrombolysis).
CDT selectively administers the thrombolytic agent into the thrombus and is often the first line of treatment [2,16,17]. We prefer the added benefits of mechanical thrombectomy, which helps to fractionate the thrombus load, thus facilitating the action and increasing the surface area for the pharmacologic agent to work. While limited data have demonstrated significant clearing of thrombus (>50 percent) in one-third of patients treated with mechanical thrombectomy alone, it is not generally recommended without a concurrent thrombolytic agent [26]. Mechanical thrombectomy alone frequently leads to rethrombosis. Although, a multicenter study of 15 patients using the ClotTriever and FlowTriever devices demonstrated adequate treatment of thrombotic iliocaval lesions without the use of thrombolytic drugs [27].
Catheter-directed pharmacologic thrombolysis — CDT is an important advance in the treatment of ICVO, particularly extensive proximal lower extremity deep vein thrombosis (DVT). CDT involves placement of a catheter into the thrombus. The main benefit of catheter-directed treatment is the delivery of concentrated drug directly at the thrombus site to dissolve the thrombus. In addition, mechanical disruption of the thrombus helps to increase the surface area, thereby augmenting the effect of the thrombolytic agent. If dissolution of the thrombus uncovers an underlying venous stenosis, treating it may help prevent rethrombosis.
Two methods are available for CDT and include the pulse spray techniques and ultrasound-assisted thrombolysis (eg, EkoSonic Endovascular System [EKOS]). Pulse spray can be started after placement of an adequate treatment zone multi-side hole catheter (eg, Unifuse, Mewissen; typically 50 cm) connected to a standard infusion pump to deliver the thrombolytic agent at a specific rate to a set dose. Ultrasound-assisted CDT also uses a multi-side hole catheter to deliver the thrombolytic agent, but a core wire, which emits high-frequency, low-intensity ultrasound, is included as a part of the catheter system. The ultrasound energy aims to disaggregate fibrin fibers, increase available surface area within the thrombus, and permit greater penetration of the thrombolytic agent. Outcomes for these two catheters are comparable [28]. The choice is guided by the operator's experience.
Percutaneous mechanical thrombectomy — Mechanical thrombectomy uses a variety of devices to break up thrombus with or without the aid of pharmacologic agents. Outcomes using mechanical thrombectomy alone have been dismal; however, for patients with extensive DVT and candidates for treatment, but in whom pharmacologic thrombolysis is contraindicated, mechanical thrombectomy by itself can be considered. Available devices include:
●Rheolytic thrombectomy – Rheolytic thrombectomy injects high-velocity saline using Bernoulli's principle to break up and aspirate clot (eg, Angiojet-Zelante [8 Fr], Angiojet-Solent [6 Fr]) [29]. Devices are placed over a 0.035 inch wire.
●Rotational thrombectomy – Rotational thrombectomy macerates thrombus using a rotating sinusoidal wire (eg, Cleaner-XT [6 Fr] and Cleaner-15 [7 Fr]) [30]. No guidewire is needed.
●Suction thrombectomy – For suction thrombectomy, a steerable delivery catheter provides a high-velocity vacuum suction to aspirate thrombus (eg, Penumbra: 4, 6, 8, and 12 Fr; ClotTriever funnel sheath: 13 Fr with catheter 13 to 25 mm [27,31]). These catheters are designed to facilitate debulking and removal of significant amounts of acute thrombus (<4 weeks) from larger veins without the need for pharmacologic agents [27,31]. These catheters can offer lytic free clot retrieval in one session. However, clot needs to be fresh to be suctioned completely.
•The ClotTriever consists of two pieces, a 13 Fr sheath equipped with a funnel at the proximal end (ie, the ClotTriever catheter) and a large-bore hemostatic valve with a large suction syringe attached designed to facilitate clot removal in concert with the funnel device. The catheter incorporates a retractable coring element that, when deployed, is designed to capture thrombus from vessels up to 16 mm in diameter, and is then directed into a long collection bag that is withdrawn through the sheath for retrieval [27,32].
•The Indigo continuous aspiration mechanical thrombectomy (CAT) system is another aspiration mechanical thrombectomy device that intended to aspirate acute thrombus without the need for administration of thrombolytic medication, thereby reducing the risk of bleeding [33]. CAT is a single-use device for aspiration of arterial or venous thrombus in any vessel except for the coronary or cranial vessels. It has three components: a catheter, a separator, and a vacuum pump. Four catheter sizes are available from 3.4 Fr to 8 Fr). The CAT 8 (8 Fr), which is used mainly for venous thrombectomy, can aspirate up to 160 mL/s. It has an angulated tip for rotational use to clear larger thrombus burdens. The separator allows thrombus fragmentation and mobilization as well as cleaning of the catheter when it is obstructed by thrombus. The vacuum pump provides continuous suction by applying and maintaining negative pressure of 29 mmHg [34].
●Cannula and circuit thrombectomy – Circuit thrombectomy uses a large-caliber suction cannula and filter, which are spliced into an extracorporeal veno-venous bypass circuit to remove thrombus (AngioVac; 22 Fr); adjuvant rotational thrombectomy devices (eg, CLEANER, Aspirex, Vetex, ThromCat, FlowTriever Catheter) may also be used.
Combined treatment: Pharmacomechanical thrombolysis — For the treatment of thrombotic ICVO, we prefer to use a combination of pharmacological CDT and mechanical thrombectomy (ie, pharmacomechanical) thrombolysis. The added benefit of mechanical thrombolysis is to fractionate the load of the thrombus to facilitate the pharmacologic phase of therapy. Many studies have shown significant reduction in thrombolytic dosage, hospital stay, and intensive care unit utilization [35,36].
Commercially available systems for pharmacomechanical thrombolysis include rotational (eg, Angiojet, Trellis), rheolytic, and ultrasound-assisted mechanical thrombectomy devices that also include a means by which to administer pharmacologic agents [37-42]. The mechanical aspects of these devices are similar to those described above. (See 'Percutaneous mechanical thrombectomy' above.)
Prophylactic IVC filter — Whether to place an inferior vena cava (IVC) filter before initiating thrombolytic therapy is controversial. The Society for Vascular Surgery (SVS) supports placement of IVC filters in selected patients, though it recommends against routine use. The decision to place a temporary IVC filter prior to pharmacomechanical thrombectomy should be based on individual patient risk factors and practitioner preference. Due to inherent long-term complications and reduced benefit after the first two weeks, the IVC filter should be retrieved as soon the indication for it no longer exists [2,43-45].
Observational studies and one trial have suggested a potential benefit for prophylactic IVC filter placement to reduce the risk of fatal embolic complications in patients undergoing venous thrombolysis [46,47]. In the author's practice, a retrievable IVC filter is often placed prior to thrombolysis and angioplasty/stenting for ICVO (image 1). Some clinicians do not place an IVC filter unless there has been significant prior PE. Proponents of not placing IVC filters point to the potential complications related to the filter itself, particularly when there is not a clear need for an ongoing/permanent filter and the filter is not retrieved. One trial evaluated the effect of IVC filter use during intervention [48]. In the Filter Implantation to Lower Thromboembolic Risk in Percutaneous Endovenous Intervention (FILTER-PEVI) trial, the use of a filter significantly lowered the risk of symptomatic PE compared with no filter (1 of 14 [1.4 percent] versus 8 of 22 [11.3 percent]) [48]. In the TORPEDO trial, 88 patients were randomly assigned to receive percutaneous endovascular venous intervention (PEVI), which included IVC filter placement, or to a control group who received only medical treatment [49]. Non-fatal PE was noted in three patients of the control group compared with none in the PEVI group, although this was not statistically significant. Fatal PE was noted in four patients of the control group versus one patient in PEVI group.
When prophylactic filter placement is chosen, it can be placed via the nondiseased common femoral vein or using a transjugular approach. The placement of IVC filters and retrieval of temporary filters are discussed in detail separately. (See "Placement of vena cava filters and their complications".)
Thrombolytic agents and dosing — Several thrombolytic agents are currently available. Streptokinase is the only thrombolytic agent approved for venous thrombolysis by the US Food and Drug Administration, but it is rarely used due to common side effects, including allergy and a higher risk of bleeding complications. Other thrombolytic agents such as recombinant tissue plasminogen activator (rtPA; alteplase, reteplase, tenecteplase) and urokinase are also available, and while these have indications primarily for arterial thrombolysis, they have been used extensively in the venous system [26,41,50,51]. The majority of reported experience has been with rtPA, but reteplase and tenecteplase have been reported in small case series.
Prior to the administration of the thrombolytic agent, a soft 0.035 inch guidewire and a guiding catheter are used to navigate through the occlusion, and when an intraluminal position is confirmed, the soft wire is exchanged for a stiff working wire (eg, Supracore). Sequential ballooning of the common iliac veins can be tried using 9 or 10 mm compliant balloons, which helps to increase the surface area for thrombolysis and to mechanically fracture and destabilize any organized thrombus.
Thrombolysis is started with an initial bolus dose of 2 to 4 mg tPA. After placement of the catheter with the patient positioned supine (or repositioned if the procedure started in the prone position), the infusion can be started. For pulse spray CDT with rtPA, accepted dosing is weight-based administration starting at 0.01 mg/kg/hr, not to exceed 1.0 mg/hr [4,52]. Low-dose heparin is administered concurrently (500 units/hour) to prevent thrombosis of the access sheath. The catheter should be firmly secured to the patient's leg before transportation to a monitored unit. (See 'Monitoring' below.)
Patients with contraindication to thrombolysis may be considered for mechanical thrombectomy. One study has showed improved functional outcomes even if thrombolysis therapy is contraindicated [53].
Monitoring — While it is common to monitor a variety of hemostatic parameters during thrombolysis to reduce the risk of unwanted bleeding, there is a paucity of reliable data upon which to make definitive recommendations regarding monitoring. Many clinicians measure platelet counts, hemoglobin, fibrinogen, fibrin degradation products, and activated partial thromboplastin time prior to and after initiation of thrombolysis. One publication and associated commentary questioned the value the monitoring fibrinogen levels in patients with pulmonary embolism treated with CDT [54,55]. Suffice it to say that there is a significant need for improved methods to accurately predict the risk of bleeding in patients undergoing venous thrombolysis.
It is common practice to reduce or discontinue tPA in the setting of dropping or very low fibrinogen levels based on data derived from the coronary literature. Because a plasma fibrinogen level (PFL) <100 mg/dL is associated with the occurrence of minor and major hemorrhagic complications [56], we usually monitor PFL and if the levels drop to <150 mg/dL, we stop the thrombolytic infusion for two hours and repeat testing. If the PFL continues to be low and the patient is stable, we continue a heparin drip at 500 units/hour via the sheath and normal saline at 20 cc/hour via the side-hole infusion catheter. If the PFL normalizes after two hours, thrombolytic therapy can be resumed [57].
The patient is reevaluated in the interventional suite at 24 hours, and additional balloon angioplasty is performed for residual stenosis, as needed. (See 'Angioplasty/stenting' below.)
ANGIOPLASTY/STENTING — For symptomatic iliocaval venous obstruction (ICVO) stenosis, stenting is preferable but is not universally agreed upon. Stenting is important for maintaining patent venous outflow in the long term [2,58-65]. Without stenting, recurrence rates are greater than 70 percent [66]. In addition, in the iliac segment, residual stenosis has been correlated to the development of post-thrombotic syndrome [67]. However, recurrence rates may depend upon underlying pathology and type of stent used [66,68].
If thrombus is present on the initial venogram, angioplasty and stenting of a stenotic ICVO lesion can only be performed once thrombus has been cleared. Once vein patency is restored using pharmacomechanical thrombolysis, as confirmed by repeat venography, angioplasty and stenting can be undertaken. (See 'Options for reducing thrombus burden' above.)
Venous stents — Using stents designed specifically for the venous system is of paramount importance in treating venous occlusive disease. Patency rates are overall high for venous stenting, particularly for nonthrombotic lesions.
●In a systematic review of venous stents with at least 30 patients and six months or more follow-up primary, assisted primary, and secondary patency rates were 71, 89, and 91 percent, respectively, with a median follow-up of two years [69]. Higher patency was reported for nonthrombotic compared with thrombotic lesions (96 versus 73 percent).
●In a study of 90 consecutive patients treated using venous stents, one-year primary, assisted primary, and secondary patency rates were 92.2, 92.2, and 93.9 percent, respectively [70]. Venous Clinical Severity Scores were also improved. Stent patency was significantly lower for thrombotic venous lesions compared with nonthrombotic lesions (86 versus 100 percent).
●In a pivotal study, 170 symptomatic patients (CEAP II or III) with a mean diameter stenosis of 78 percent underwent treatment with a self-expanding nitinol venous stent [71]. Among 127 patients with chronic post-thrombotic obstruction, mean lesion length was 125.3 mm. Initial technical success was high, and freedom from major adverse events through 30 days was 98.8 percent. The one-year primary patency rate for the entire group was 84 percent and was lower for chronic post-thrombotic disease (79.8 versus 96.2 percent).
It is important to consider specific stent characteristics, such as foreshortening, radial pressure, and collapse. Knowledge of the maximal foreshortening of the initial length is imperative for planning stent placement and coverage. In one review, maximal foreshortening values for three venous stents were: 11.3 percent of the Cook Z stent, 14.2 percent for the Cook Vena stent, and 88.7 percent for the Wallstent. While subject to more foreshortening, steel stents (eg, Wallstent) have more radial force and are less compliant compared with nitinol stents (Cook Z), and therefore may be more useful for treating pinch force lesions such as those found in May-Thurner syndrome [72].
Stent failure is mainly related to technical factors, such as new or missed stenosis in native iliac vein, inadequate stent expansion, or the use of unilateral iliac stent that extends into the inferior vena cava (IVC) obstructing flow from the contralateral iliac vein [73]. Yet, there is a role for using pharmacological adjuncts to maintain stent patency. To optimize patency, the authors of a respected study suggested that without substantial evidence to demonstrate efficacy for stents in venous occlusive disease, the use of adjunct antiplatelets in primary nonthrombotic lesions and the consideration of anticoagulant in thrombotic ones appears to be reasonable [74]. (See 'Antithrombotic therapy' below.)
General technique — Once the vein is clear of thrombus, if it was present, intravascular ultrasound (IVUS) is used to characterize the location and severity of stenotic lesions and to calibrate the size of the vein before stent placement. A self-expanding stent is typically used and positioned in the region of the stenosis. The stent diameter is chosen to be 20 percent larger than the normal vein diameter. In the author's practice, stent diameter sizes are typically between 12 and 24 mm, depending on the size of the target vein. Once deployed, the stent is dilated using a balloon to open the stent with a 1:1 ratio (ie, no oversizing). (See 'Intravascular ultrasound' above.)
●For cases in which a thrombosed IVC filter is encountered, the filter can be crossed with a guidewire and in some cases will respond to a high-pressure balloon. At other times, a second stent may be needed. The second stent (eg, Wallstent) will crush and displace the occluded IVC filter laterally. Special attention needs to be given to the renal veins and every effort made to stay below them. Suboptimal results may require deployment of a balloon-expandable stent (eg, Palmaz stent P4010) mounted onto a 14 to 18 mm balloon (eg, Maxi LD) to provide sufficient radial force to maintain the lumen of IVC. Placing a "kissing stent" (self-expanding) distally (caudally) into each common iliac vein completes treatment.
●Prior to iliac vein stenting, a 10 mm noncompliant balloon can be used to predilate the lesion. For a more distal (caudal) lesion, a smaller noncompliant balloon can be used. Following angioplasty, it is imperative to stent all diseased segments. At times, it may be necessary to extend the stent to or below the inguinal ligament to recanalize the iliofemoral segment. If there is a technical need, interventionists should be careful about extending a standard stent with small interstices (eg, Wallstent) into the IVC due to the possibility of jailing the contralateral common iliac vein [68,75-77]. A later-generation stent with larger interstices (eg, Gianturco Z-stent) has been designed for this situation to minimize the impedance to venous flow by the protruding stent, and it may also help maintain patency by reinforcing the iliocaval junction [78].
●When the femoropopliteal segment is involved, a long balloon (eg, 5 mm x 10 cm) can be used to angioplasty the vein from proximal to distal (cranial to caudal). Stenting the femoropopliteal vein segment may also be needed; however, every effort should be made not to cover the confluence of the deep femoral vein.
Completion venography along with IVUS examination is necessary to confirm the adequacy of treatment. Successful recanalization in our practice is defined with residual stenosis <30 percent (any site; IVC, iliac, femoral, popliteal); still, some respected authorities consider <50 percent as satisfactory [79].
Following stenting, antiplatelet therapy is initiated immediately. (See 'Antithrombotic therapy' below.)
Specific techniques
●Mechanical thrombectomy – With the patient in the prone position, ultrasound-guided access of the popliteal vein is obtained, upgrading to an 8 Fr sheath. The patient is systemically anticoagulated typically with unfractionated heparin (80 units/kg) or an alternative agent (eg, Angiomax) for those with contraindications. Venography is performed to confirm the presence and extent of deep vein thrombosis. Intravascular ultrasound (IVUS) can be used as well to delineate the extent of thrombotic lesion and any possible underlying pathology. An exchange length guidewire (eg, Supracore) is placed, and at this time, the sheath is exchanged for 13 Fr ClotTriever sheath, and the ClotTriever catheter is inserted over the guidewire and positioned in the IVC. The nitinol basket bag is deployed, the device is withdrawn through the thrombotic segment, and thrombus is extracted and removed via the 13 Fr sheath. Multiple passes (in author's experience up to six passes) may be required, and there is no limit to how many times it can be used. The nitinol basket is very durable, so it can be easily removed, cleaned, resheathed, and redeployed. Final venography and IVUS confirm patency and identify any underlying pathology such as May-Thurner syndrome that requires angioplasty and stenting.
●Stent placement and orientation – Several options are available for stenting chronic iliocaval venous obstruction and include placement of two stents side by side (double-barrel stent), the inverted Y stent in which another iliac stent is deployed through a "fenestration" of previous stent across the caval confluence, and stent apposition as close as possible to the previously deployed stent at the caval confluence. One review evaluated stent technique for 230 limbs with ICVO, the authors concluded that the barrel technique was optimal and should be performed, if feasible. A high number of reinterventions were reported for the apposition technique.
●Whether to cover the contralateral iliac vein ostium – Covering the contralateral iliac vein during unilateral IVCO is a valid concern. In a review of 261 patients (177 nonthrombotic, 84 thrombotic), stent placement for nonthrombotic ICVO [80] had 97 percent long-term primary patency rate and 100 percent assisted primary patency rate. Encroachment of the contralateral iliac vein was relatively safe with <1 percent of those who had a stent placed ≥5 mm into the confluence of IVC developing a thrombotic event at a median follow up of 62 months.
Another systematic review [81] of 12 studies with total 1864 patients reported incidence of contralateral iliac vein thrombosis up to 15.6 percent. In the author's opinion, incidence of contralateral iliac vein thrombosis in the event of partially or totally covering the confluence of IVC is not negligible, and every effort should be pursued not to cover the contralateral ostium of iliac vein, and if that accidentally occurs, a long-term antithrombic medications should be considered, if feasible.
●Iliocaval venous anomalies – Iliocaval venous anomalies (ICVAs) are not uncommon and often encountered during venogram. It is imperative to be aware of them since they may be more prevalent than previously thought. In one study, the prevalence of ICVAs was 15 percent (129 of 845 patients) [82]. A high IVC confluence occurred (bifurcation was above L4-L3 disc space) in 56 percent of patients, followed by right internal iliac vein draining into proximal left common iliac vein in 22.5 percent and double IVC in 8.5 percent. This review highlights the importance of performing a full venogram prior to any angioplasty/stenting. While IVUS is critical to calibrate area of stenosis/obstruction, it may not be adequate to evaluate the venous bed prior to stenting.
Example cases — May-Thurner Syndrome (MTS) is a common underlying cause of ICVO, but other etiologies should be considered as well. The following cases illustrated the author's practice.
●Classic May-Thurner syndrome — A young female in her early twenties presented with acute deep vein thrombosis (image 2). Magnetic resonance angiography was suspicious for MTS (image 3 and image 4 and image 5).
●Bilateral May-Thurner syndrome – A female in her early thirties with severe bilateral lower extremity swelling and bilateral venous claudication. Following bilateral iliac vein stenting, venography showed resolution of venous collaterals (image 6), and IVUS showed resolution of the stenoses (movie 1 and movie 2).
●Pediatric May-Thurner syndrome – Adolescent female with thrombotic May-Thurner syndrome (image 7).
●Acquired May-Thurner syndrome – Older male presenting with acute DVT after remote history of endovascular aortic aneurysm repair (image 8).
●IVC filter thrombosis – Older female with prior history of DVT and filter placement with extensive swelling (image 9).
●Post-thrombotic syndrome with IVC stenosis – Older male with bilateral with bilateral post-thrombotic syndrome and IVC filter stenosis (image 10).
POSTPROCEDURE CARE AND FOLLOW-UP — After completion of the endovascular intervention and before leaving the interventional suite, compression dressings are placed to augment venous drainage once the outflow obstruction is relieved. Special attention should be paid to maintaining adequate elevation of the foot of the bed to at least 30° and also in using bilateral sequential pneumatic compression devices. Early ambulation is recommended.
Follow-up appointments are scheduled for one, three, and six months postprocedure, then annually thereafter. At each office visit, a full clinical examination is performed to document level of activity and the presence and degree of any limb swelling, skin changes, and progress of any venous ulcer healing. Vascular imaging is indicated for any recurrence of symptoms.
Antithrombotic therapy — Even among experts in the field, there is no consensus on the optimal type and duration of antithrombotic regimen after angioplasty and stenting for venous occlusive disease. There are no data from randomized trials to guide decisions on antithrombotic therapy, and as a result, clinical practice varies widely [74,83-87]. Our general approach is as follows:
●Patients with acute iliocaval venous thrombosis (ie, thrombotic) should receive therapeutic anticoagulation with dosing, and duration as per venous thromboembolism (VTE) guidelines [2,88,89].
•For patients who undergo venous angioplasty, but no stent has been deployed, we suggest aspirin (81 mg) daily.
•For those who undergo venous stenting at low risk for bleeding, we suggest clopidogrel for a period of four to six weeks, then aspirin indefinitely. (See 'Our approach after venous stenting' below.)
●For patients with chronic iliocaval venous disease (ie, nonthrombotic), after a stent has been deployed, we suggest dual antiplatelet therapy with clopidogrel in addition to aspirin for four to six weeks, then aspirin indefinitely. (See 'Our approach after venous stenting' below.)
For those with an increased risk for bleeding, antiplatelet therapy is individualized but often consists of aspirin alone. We suggest not using triple antithrombotic therapy (ie, anticoagulation and dual antiplatelet therapy) because of its inherent increased risk of major bleeding. Anticoagulation options, dosing and the duration of therapy for patients with deep vein thrombosis (DVT) are reviewed separately. (See "Overview of the treatment of proximal and distal lower extremity deep vein thrombosis (DVT)", section on 'Patients at low risk of bleeding' and "Selecting adult patients with lower extremity deep venous thrombosis and pulmonary embolism for indefinite anticoagulation".)
Variability of use after venous intervention — While there is little debate over the need for ongoing anticoagulation among those who undergo venous intervention for thrombotic disease (acute, post-thrombotic), the need for and selection of antithrombotic therapy for nonthrombotic disease is controversial. Some believe the role for antiplatelet therapy is less for the slower flow/lower shear venous system compared with the arterial system [74,90]. However, generally speaking, the vascular response to stent placement in the venous bed is similar to stented arteries, with endothelial injury activating the coagulation cascade at the site of stenting [91] and inflammatory changes promoting neointimal hyperplasia [92-94]. The evidence supporting the use of antiplatelet agents is largely indirect and extrapolated from recommendations for antiplatelet therapy based on studies demonstrating improved patency of arterial stents [74,95-99]. However, studies evaluating specific antithrombotic regimens following venous stenting are emerging. As in arterial disease, the goal of antithrombotic therapy following venous stenting is to maintain long-term patency of the revascularization and to mitigate adverse systemic outcomes.
The variability in practice is illustrated in the following review that examined the antithrombotic regimen used in 151 patients following iliac vein stenting [100]:
●Thirty-eight percent received triple therapy (anticoagulation plus dual antiplatelet therapy), 17 percent received anticoagulation only, 14 percent received anticoagulation plus a single antiplatelet agent, 10 percent received dual antiplatelet therapy only, 7 percent received a single antiplatelet agent, and 15 percent received no antithrombotic therapy. Not surprisingly, those with acute DVT and those with a prior history of DVT were more likely to be anticoagulated.
●The duration of antithrombotic therapy was also variable. When anticoagulation was prescribed (104 patients), 31 percent received indefinite therapy, 22 percent were anticoagulated for six months, and 12 percent were anticoagulated for three months. Patients with a history of prior DVT or thrombophilia were more likely to be prescribed indefinite anticoagulation. Aspirin was the most common agent used for an indefinite duration (62 of 88 patients), while it was common to prescribe clopidogrel for just three months (60 of 89 patients).
●Triple antithrombotic therapy (anticoagulation with dual antiplatelet therapy) significantly reduced the odds of experiencing in-stent stenosis/stent thrombosis when compared with dual antithrombotic therapy, but pairwise comparisons of the remaining treatment groups did not yield significant differences. Whether triple therapy improved the odds of in-stent restenosis/stent thrombosis compared with combinations that also included an anticoagulant agent could not be evaluated due to the small size of these subgroups.
●Importantly, there were no major bleeding events observed in the dual antiplatelet or single antiplatelet groups.
Our approach after venous stenting — For patients who undergo venous stenting, we use the following approach [2,10,50].
●For patients with acute/subacute thrombotic iliocaval lesions, we continue anticoagulation after thrombolysis. Parenteral anticoagulation should be resumed within four hours after sheath removal and transitioned to oral anticoagulation. Therapeutic anticoagulation is continued using dosing, duration and monitoring per VTE guidelines [2,88,89]. Generally, anticoagulation can be discontinued (typically after six months) when the underlying anatomic venous pathology provoked the thrombotic event and after satisfactory imaging of the iliocaval segment shows complete resolution of the clot burden and the underlying stenosis. Immediately after stent placement, we provide a 300 mg oral loading dose of clopidogrel and continue clopidogrel 75 mg daily for three months, after which we discontinue clopidogrel and give aspirin 81 mg daily indefinitely. Antiplatelet therapy is individualized in those with an increased risk for bleeding.
●For patients with recurrent thrombotic iliocaval lesions, parenteral anticoagulation should be resumed within four hours after sheath removal and transitioned to oral anticoagulation. Therapeutic anticoagulation is continued indefinitely given the high risk of thrombosis [2,88,89]. Immediately after stent placement, we provide a 300 mg oral loading dose of clopidogrel and continue clopidogrel 75 mg daily for three months after which we discontinue clopidogrel and give aspirin 81 mg daily indefinitely. Antiplatelet therapy is individualized accordingly for those with an increased risk for bleeding.
●For patients with nonthrombotic lesions (eg, May-Thurner syndrome, chronic venous changes), immediately after stent placement, we provide a 300 mg oral loading dose of clopidogrel. For patients at low risk for bleeding, we suggest dual antiplatelet therapy using clopidogrel (75 mg daily) and aspirin 81 mg for four to six weeks, after which we discontinue clopidogrel and continue aspirin indefinitely. Antiplatelet therapy is individualized for those at an increased risk for bleeding.
Compression hosiery — Patients are instructed to use graded compression stockings as part of their daily routine [2]. Following successful intervention for symptomatic ICVO and to help reduce the incidence of post-thrombotic syndrome, we prescribe knee or thigh-high compression stockings (30 to 40 mmHg) for at least two years and indefinitely, if tolerated [2]. (See "Compression therapy for the treatment of chronic venous insufficiency" and "Post-thrombotic (postphlebitic) syndrome".)
OUTCOMES — Under most circumstances, treatment of iliocaval venous obstruction (ICVO) will improve hemodynamics, most symptoms related to venous hypertension, as well as quality-of-life (QOL) [35,101-105]. Outcomes in patients with ICVO related to May-Thurner syndrome are reviewed separately. (See "May-Thurner syndrome", section on 'Efficacy of endovenous therapy'.)
Complications of endovascular therapy include bleeding related to the use of thrombolytic agents and complications related to the placement of venous stents, which include the following: "jailing" the contralateral common iliac vein, which can lead to thrombosis [68,77]; rupture of the iliac vein; stent migration or displacement; and erosion of stent into an overlying artery.
Patency and reintervention — Initial technical success for the treatment of iliocaval lesions in most series is high, with one-year patency rates (primary, assisted) greater than 90 percent (table 1) [35,106,107].
The patency of stents used to treat nonthrombotic lesions appears to be better compared with post-thrombotic disease [75,108,109]. In a review that included 982 obstructive lesions, the primary, assisted primary, and secondary cumulative patency rates were 79, 100, and 100 percent for patients with nonthrombotic disease compared with 57, 80, and 86 percent for patients with thrombotic disease, respectively [75]. Severe in-stent restenosis (>50 percent) has been observed in 5 to 15 percent of limbs after iliofemoral venous stenting [61,75]. In one study, the cumulative, overall rate of severe in-stent restenosis was 5 percent at 72 months, but significantly higher in thrombotic compared with nonthrombotic limbs (10 versus 1 percent) (image 11) [61].
Stent occlusion after IVCO stenting is a rare occurrence. Of the patients who have undergone iliofemoral venous stenting, 5 to 20 percent may require reintervention for in-stent restenosis with or without stent compression [110-112]. Reintervention for in-stent restenosis has been associated with good and durable relief of symptoms with cumulative improvement in pain and swelling at 18 months after reintervention for stenosis >60 percent [113]. In a large retrospective study, the primary, primary-assisted, and secondary patency at 60 months after reintervention for in-stent restenosis was 70, 98, and 84 percent, respectively [112].
Quality of life — Many studies have highlighted the socioeconomic burden of post-thrombotic syndrome (PTS) on QOL [3,114-117]. Endovenous intervention for ICVO is associated with reduced severity of PTS symptoms and improved quality of life [118]. In a study of 938 patients with chronic ICVO with and without venous reflux, complete relief of pain was achieved in 82 and 77 percent of patients, respectively [119]. In addition, complete relief of swelling occurred in 47 and 53 percent, respectively; stasis ulcer healing in 67 and 76 percent, respectively; and overall clinical improvement in 75 and 79 percent, respectively.
Some studies have suggested using the Chronic Venous Insufficiency Quality of Life Questionnaire (CIVIQ) to provide a subjective analysis of pain, sleep disturbance, morale, and social activities, including routine and strenuous physical activities, before and after intervention. The CIVIQ assessment has proven to be specific and relevant to chronic venous disease. In several reviews, CIVIQ improved significantly after intervention (doubled in three of the five indicated categories) [75,104,120]. There is also a direct correlation between quality-of-life and revised Venous Clinical Severity Score (VCSS) (calculator 1). Improved QOL can also be demonstrated in those with improved Short Form (36) Health Survey (SF-36) scores, and Venous Insufficiency Epidemiologic and Economic Study quality-of-life questionnaire (VEINES-QOL) scores and its validated subscale of 10 items on venous symptoms (VEINES-Sym) scores [115]. (See "Classification of lower extremity chronic venous disorders", section on 'Measures of clinical severity' and "Classification of lower extremity chronic venous disorders", section on 'Disease-specific quality-of-life measures'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Superficial vein thrombosis, deep vein thrombosis, and pulmonary embolism" and "Society guideline links: Chronic venous disorders".)
SUMMARY AND RECOMMENDATIONS
●Iliocaval venous obstruction (ICVO) is an underrecognized venous pathology with an increasing incidence. Proceeding with endovenous treatment of ICVO depends upon the severity of symptoms and whether thrombus is present (ie, nonthrombotic ICVO, thrombotic ICVO). (See "Overview of iliocaval venous obstruction", section on 'Approach to venous intervention'.)
●For patients with moderate-to-severe symptoms related to nonthrombotic ICVO, treatment is targeted toward reducing the severity of the chronic venous stenosis/occlusion. Restoring patency of the venous outflow reduces swelling, aids healing of ulcers (if present), and improves overall quality of life. (See 'Angioplasty/stenting' above and 'Outcomes' above.)
●For patients with thrombotic ICVO and appropriate indications for treatment, we suggest pharmacomechanical thrombolysis rather than catheter-directed thrombolysis alone or percutaneous mechanical thrombectomy alone (Grade 2C). The added benefit of mechanical thrombolysis is to fractionate the load of the thrombus to facilitate the pharmacologic thrombolysis. Pharmacomechanical thrombolysis reduces the dose of the thrombolytic agent and reduces hospital stay and intensive care unit utilization.
●For patients with stenotic ICVO lesions (May-Thurner syndrome, chronic venous changes), we suggest angioplasty and stenting, rather than angioplasty alone (Grade 2C). Angioplasty alone is associated with higher rates of recurrent stenosis and thrombosis. (See 'Angioplasty/stenting' above.)
●Our approach to antithrombotic therapy following iliocaval venous intervention is as follows: (See 'Antithrombotic therapy' above.)
•Patients with acute iliocaval venous thrombosis (ie, thrombotic) should receive therapeutic anticoagulation with dosing, and duration as per venous thromboembolism (VTE) guidelines. (See "Overview of the treatment of proximal and distal lower extremity deep vein thrombosis (DVT)", section on 'Patients at low risk of bleeding'.)
In addition:
-For patients who undergo venous angioplasty, but no stent has been deployed, we suggest aspirin (81 mg) daily, rather than no antiplatelet therapy (Grade 2C).
-For patients at low risk for bleeding, after stenting we suggest monotherapy using clopidogrel alone for a period of four to six weeks, rather than no therapy or dual antiplatelet therapy (Grade 2C). Thereafter, we suggest aspirin indefinitely, rather than no antiplatelet therapy (Grade 2C). (See 'Our approach after venous stenting' above.)
•For patients with chronic iliocaval lesion (ie, nonthrombotic; May-Thurner, chronic post-thrombotic changes) at low risk for bleeding, after stenting we suggest dual antiplatelet therapy using clopidogrel and aspirin for four to six weeks, rather than monotherapy or no therapy (Grade 2C). Thereafter, we suggest aspirin indefinitely, rather than no antiplatelet therapy (Grade 2C). (See 'Our approach after venous stenting' above.)
•For patients with an increased risk for bleeding, antiplatelet therapy after iliocaval venous stenting is individualized, but often consists of aspirin alone. For all patients, we avoid triple antithrombotic therapy (ie, anticoagulation and dual antiplatelet therapy) because of its inherent increased risk of major bleeding. (See 'Antithrombotic therapy' above.)
آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟
