Chronic Venous Obstruction Research Articles

Thrombosis of Cross-pubic Collateral Veins After a Long Haul Flight in a Patient With Chronic Left Ilio-femoral Venous Obstruction

Thrombosis of Cross-pubic Collateral Veins After a Long Haul Flight in a Patient With Chronic Left Ilio-femoral Venous Obstruction

PC184 Delayed Conversion to Kissing Stent Configuration in the Setting of Unilateral Iliac Vein Stenting

Iliac vein stents are being increasingly used to treat chronic proximal venous outflow obstruction. Among patients with unilateral stenting in the proximal common iliac vein with extension into the inferior vena cava (IVC), a small number of patients presented with venous symptoms related to outflow obstruction of the contralateral common iliac vein. While the incidence of this complication of iliac vein stenting is unknown, this abstract presents one technical approach to this complication. We present 11 patients with outflow obstructive symptoms in the contralateral iliac vein after a prior IVC common iliac vein stent placement. Postanesthesia, ultrasound guidance is used to obtain access to the common femoral vein bilaterally. Inferior vena cavograms and venograms of the iliac veins are undertaken using contrast in digital subtraction mode. Intravascular ultrasound (IVUS) using a Volcano Visions PV .035 Digital IVUS catheter (Volcano Corporation, San Diego, Calif) is then used to evaluate the iliac veins and assess the degree of stenosis in each vein segment. The use of IVUS is critical to locate the narrow channel present between the contralateral stent and wall of the IVC, assist passage of the guidewire through this narrow channel, and ensure that the guidewire does not pass through the interstices of the stent (Fig 1). Balloon angioplasty is seldom necessary. The initial guidewire is then exchanged for a stiff 0.35-inch × 180-cm guidewire. Next, a 16-mm or 18-mm stent is positioned alongside the existing stent in a kissing iliac stents configuration. After the newly placed stent is deployed, both stents are simultaneously dilated with either 16-mm or 18-mm balloons (Fig 2). Finally, a completion venogram and IVUS confirm fully expanded stents. This procedure was performed in 11 patients (6 males, 5 females), with three performed on the right iliac vein and eight on the left iliac vein. The mean time to development of contralateral occlusive symptoms was 626 days from the initial stenting. Average follow-up time from the second stenting was 167 days, with no postoperative complications. Eight patients reported significant symptomatic improvement in their newly treated limb at 30 days postoperatively, while 10 patients did at 90 days postoperatively. No patients reported any worsening symptoms in either limb. Delayed conversion to a kissing stent configuration can be considered for treatment of contralateral iliac vein outflow obstruction in the setting of previous unilateral iliac vein stenting.Fig 2View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Secondary Interventions After Iliac Vein Stenting for Chronic Proximal Venous Outflow Obstruction

Iliac stent placement is an increasingly common procedure in the treatment of chronic proximal venous outflow obstruction (PVOO), but secondary interventions after vein stent placement remain poorly characterized. Our goals were to identify the incidence, indications, operative findings, and outcomes of secondary interventions after the primary iliac vein stent procedure in a single institution. We retrospectively reviewed the clinical history of 490 patients (42.41% male; mean age, 60.77 years [range, 18-92 years]; 93.28% follow-up with a mean follow-up of 308.59 days) who underwent iliac stent placement (Wallstent; Boston Scientific, Marlborough, Mass) for PVOO between October 2013 and June 2016. We specifically evaluated the clinical presentation, intraoperative findings, and outcomes among those patients who required a secondary intervention after an initial iliac vein stent procedure. Secondary interventions after an initial stent placement were identified in 50 of 490 patients (10.2%; mean age, 61.54 years [range, 19-92 years]; 58% female [n = 29]). Among these 50 patients, 56% (n = 28) of secondary interventions were due to recurrence of symptoms after the initial stent surgery, 24% (n = 12) were due to the development of new symptoms, and 20% (n = 10) were due to persistence of symptoms. Intraoperative findings during the secondary intervention included migration of the stent (8% [n = 4]), acute deep venous thrombosis/thrombosis (12% [n = 6]), an additional lesion (ie, stenosis in a native iliac vein proximal or distal to the original lesion; 50% [n = 25]), stenosis within the stent (stent stenosis without finding of thrombus or isolated, focal intrastent thrombosis; 16% [n = 8]), impairment of flow of the contralateral vessel from the previous stent (12% [n = 6]), and no finding (2% [n = 1]). The types of secondary interventions were placement of a new stent (80% [n = 40]), isolated balloon angioplasty alone (6% [n = 3]), and catheter PMT (14% [n = 7]). Significant symptomatic improvement was observed after the secondary intervention in 90% of patients (n = 45); 2% (n = 1) of patients experienced only a transient improvement, and 8% of patients (n = 4) reported no improvement in their symptoms. This study establishes a secondary intervention rate of 10% after iliac vein stent placement for chronic PVOO, identifies discrete and definable intraoperative findings as targets for quality improvement, and indicates that secondary interventions after vein stent placement are associated with a good outcome.

Abdominal and pubic collateral veins as indicators of deep venous obstruction.

Chronic deep venous obstruction can cause a significant loss of quality of life, although it can be treated successfully by stenting. A clear referral pattern for additional imaging is warranted in patients with lower limb complaints. The aim of this study was to determine the value of clinically visible abdominal wall collateral veins in the diagnosis of a potentially treatable deep venous obstruction. A total of 295 patients referred for evaluation at a tertiary venous clinic with a collateral vein on the abdominal wall or pubic bone, visible on physical examination, were retrospectively analyzed and compared with a randomly selected control group of 365 patients without such a collateral vein. Duplex ultrasound, magnetic resonance venography, computed tomography venography, and conventional venography were used to determine the presence or absence of deep venous obstruction. Mean age of the group with a positive collateral was 43.5± 13.7 (6-76) years compared with 44.7± 14.2 (16-89) years in the control group. In the collateral group, 66.1% werefemale compared with 63.3% in the control group. Sensitivity of the abdominal wall collateral vein for any obstruction atthelevel of the groin or more proximal was53%(95% confidence interval [CI], 48-57); specificity, 86% (95%CI, 79-91); positive predictive value, 93% (95% CI, 90-96); and negative predictive value, 32% (95% CI, 28-37). Sensitivity was 68% (95%CI, 62-73) for higher degrees of post-thrombotic obstruction and 27% (95%CI, 19-36) in iliacveincompression. A collateral vein on the abdominal wall or acrossthe pubic bone in patients with complaints of the lowerlimb has an excellent positive predictive value for deepvenous obstructive disease at the level of the groin orhigher.Such collateral veins should therefore not be removed, and symptomatic patients could be offered furtherdiagnostics and treatment.

Interventional treatment of postthrombotic syndrome.

BackgroundPostthrombotic syndrome (PTS) is the development of symptoms and signs of chronic venous insufficiency following deep vein thrombosis (DVT) and has a significant negative effect on the quality of life. The current understanding is that the clinical manifestation of PTS is related more to venous obstruction than it is to venous reflux. The use of interventional techniques for the treatment of venous obstruction and/or venous occlusion has rapidly increased in recent years.ObjectiveThis article summarizes the current concept of endovenous and hybrid interventions and presents the optimized treatment of choice in patients with chronic symptomatic venous obstruction.MethodsWe performed a systematic literature search in the Medline database to identify relevant studies on the treatment of patients with PTS.ResultsA meta-analysis of the relevant studies showed that this minimally invasive procedure is an effective treatment option with low morbidity and no mortality. Use of the newly developed dedicated venous stents showed promising results with good mid-term patency rates and a significant decrease in related symptoms.ConclusionInterventional therapy for the treatment of symptomatic chronic venous obstruction has become the method of choice in recent years. More studies are needed to evaluate the long-term success rate of dedicated venous stents.

Abstract 36: Alpha 2-antiplasmin Prevents the Resolution of Deep Vein Thrombosis

Introduction: Deep venous thrombosis is a major cause of death and disability. Despite anticoagulation treatment, venous thrombi persist for months, causing chronic venous obstruction, inflammatory remodeling and post-thrombotic syndrome. The mechanisms responsible for impaired clearance of venous thrombi are poorly understood. Alpha 2-antiplasmin (a2AP) is the primary physiological inhibitor of plasmin and a key regulator of the fibrinolytic pathway. The role of a2AP in the resolution of venous thrombosis has not been determined. Hypothesis: We tested the hypothesis that a2AP prevents the resolution of experimental deep venous thrombi. Methods and Results: Thrombus resolution and content were examined in a2AP +/+ and a2AP -/- mice using a well-established, fibrinolytic-resistant, stasis model induced by ligation of the inferior vena cava (IVC). Thrombus weight and composition were determined after 7 days. Data was analyzed by one-way ANOVA with Neumann-Keul’s correction. Thrombus weight was reduced in a2AP -/- mice by >90% when compared to a2AP +/+ mice (p<0.001); there was no significant difference between a2AP -/- mice and shams. Histochemical and immunofluorescence staining showed significant reductions in IVC fibrin content, neutrophil recruitment and matrix metalloproteinase-9 expression in a2AP -/- mice (p<0.001) vs. a2AP +/+ mice. The relative effect of plasminogen activation and a2AP on resolution of preformed venous thrombi was examined in wild-type a2AP +/+ mice treated 24 h after IVC ligation with tissue plasminogen activator (TPA) (1.2 or 5 mg/kg) or a monoclonal antibody inactivating a2AP (10 mg/Kg). By comparison to 7 day old venous thrombi in untreated mice, treatment with TPA at 1.2 mg/kg or 5 mg/kg did not decrease thrombus size after 7 days. In contrast, a2AP inactivation significantly reduced thrombus weight vs. untreated and TPA-treated mice (p<0.01 to p<0.001). Conclusions: In experimental venous thrombosis, a2AP was required for the persistence of venous thrombi 7 days after formation. Venous thrombi resisted TPA, but were sensitive to resolution after a2AP inactivation. This suggests that a2AP may be responsible for the persistence of clinical venous thrombosis in humans.

Creating arteriovenous fistulas in patients with chronic central venous obstruction.

Central venous obstruction Occlusion (CVO) has been considered a contraindication for creating a vascular access due to fear of developing a swollen extremity. However, many of these individuals developed large collateral veins and are asymptomatic. We report our experience constructing arteriovenous fistulas (AVFs) in these challenging patients. Patients with a new AVF constructed in the presence of known CVO were identified. Venous imaging confirmed proximal obstruction and extensive collateral venous return. The AVF was constructed in the extremity with the most favorable ultrasound vessel mapping and collateral central venous outflow. Arterial inflow via the radial artery was utilized when feasible. AVFs associated with known CVO were constructed in 19 patients during an eight-year time period. The mean age was 53 years, 63% were female, and 58% diabetic. Arterial inflow was from the radial artery in 15 patients and the brachial or axillary artery in 5 individuals. Post-operative AVF flow volumes were 415-910 mL/min (mean = 640 mL/min). Eight patients (42%) developed some degree of arm edema. Two resolved without intervention. The others required inflow banding (n = 2), outflow branch coiling (n = 1), and/or recanalization with angioplasty (n = 4) of the CVO to resolve swelling. Mean follow-up was 14 months. Two AVFs failed at 8 and 16 months. Primary and cumulative patency rates were 49% and 100% at 12 months and 39% and 80% at 24 months, respectively. CVO need not preclude the creation of a successful AVF. Extensive venous collaterals and avoiding high-flow AVFs are important elements for success. Cumulative patency was 80% at 24 months.

The value of hemodynamic measurements by air plethysmography in diagnosing venous obstruction of the lower limb.

Air plethysmography (APG) is a functional, noninvasive test that can assess volumetric changes in the lower limb and might therefore be used as a diagnostic tool in chronic deep venous disease. However, use of APG in chronic deep venous obstructive disease remains debatable. This study assessed the clinical value of APG in identifying chronic deep venous obstruction. All patients referred to our tertiary, outpatient clinic between January 2011 and August 2013 with chronic venous complaints and suspected outflow obstruction underwent an outflow fraction (OF), ejection fraction (EF), and residual volume fraction (RVF) test using APG. Duplex ultrasound and magnetic resonance venography were used to establish whether and where obstruction was present. Diagnostic values of these tests were assessed for obstructions at different levels of the deep venous system. A total of 312 limbs in 248 patients were tested. Mean age was 45.5± 14.0 years, and 62.5% were female. Inpost-thrombotic disease, specificity and positive predictive value for OF were as high as 98.4% and 95.0%, respectively; however, sensitivity was 34.8% and negative predictive valuewas 29.6%, with no clinically relevant positive or negative likelihood ratios. No clinically relevant differences were observed in stratifying for level of obstruction. EF and RVFwere as inconclusive. Neither could these parameters beused in diagnosing nonthrombotic iliac vein compression. We found a poor correlation between OF, EF, or RVF, determined by APG, and the presence of chronic deep venous obstruction. Therefore, use of its relative parameters is unwarranted in daily clinical practice.

The Pathology of Chronic Post-Thrombotic Venous Obstruction is not Chronic Thrombus

The Pathology of Chronic Post-Thrombotic Venous Obstruction is not Chronic Thrombus

Criteria for detecting significant chronic iliac venous obstructions with duplex ultrasound.

The purpose of this study was to determine the sonographic criteria for diagnosis of iliac venous outflow obstruction by assessing the correlation of this method with intravascular ultrasound (IVUS) in patients with advanced chronic venous insufficiency (CVI). The evaluation included 15 patients (30 limbs; age, 49.4± 10.7years; 1 man) with initial CVI symptoms (Clinical class, Etiology, Anatomy, and Pathophysiology [CEAP] classification, CEAP1-2) in group I (GI) and 51 patients (102 limbs; age, 50.53± 14.5years; 6 men) with advanced CVI symptoms (CEAP3-6) in group II (GII). Patients from both groups were matched by gender, age, and race. The Venous Clinical Severity Score was considered. All patients underwent structured interviews and duplex ultrasound (DU) examination, measuring the flow phasicity, the femoral volume flows and velocities, and the velocity and obstruction ratios in the iliac vein. The reflux multisegment score was analyzed in both groups. Three independent observers evaluated individuals in GI. GII patients were submitted to IVUS, in which the area of the impaired venous segments was obtained and compared with the DU results and then grouped into three categories: obstructions<50%, obstructions between 50% and 79%, and obstructions ≥80%. The predominant clinical severity CEAP class was C1 in 24 of 30 limbs (80%) in GI and C3 in 54 of 102 limbs (52.9%) in GII. Reflux was severe (reflux multisegment score ≥3) in 3 of 30 limbs (10%) in GI and in 45 of 102 limbs (44.1%) in GII (P< .001). There was a moderately high agreement between DU and IVUS findings when they were grouped into three categories (κ= 0.598; P< .001) and high agreement when they were grouped into two categories (obstructions<50% and ≥50%; κ= 0.784; P< .001). The best cutoff points and their correlation with IVUS were 0.9 for the velocity index (r=-0.634; P< .001), 0.7 for the flow index (r= -0.623; P< .001), 0.5 for the obstruction ratio (r= 0.750; P< .001), and 2.5 for the velocity ratio (r= 0.790; P<.001). Absence of flow phasicity was observed in 62.5% of patients with obstructions ≥80%. An ultrasound algorithm was created using the measures and the described cutoff points with accuracy of 86.7% for detecting significant obstructions (≥50%) with high agreement (κ= 0.73; P< .001). DU presented high agreement with IVUS for detection of obstructions ≥50%. The velocity ratio in obstructions ≥2.5 is the best criterion for detection of significant venous outflow obstructions in iliac veins.

Hypertension portale non cirrhotique idiopathique : indications et conduite pratique du traitement

Idiopathic non-cirrhotic portal hypertension is an under-estimated cause of portal hypertension. The diagnosis requires the exclusion of cirrhosis, common causes of chronic liver disease and venous obstruction of the portal and hepatic veins. It has been associated with various extra-hepatic conditions that are most frequently immunologic, prothrombotic, hematologic and toxic. The most frequent clinical complications are variceal hemorrhage and portal vein thrombosis. Complications of portal hypertension should be managed as in patients with cirrhosis.

Iliocaval Confluence Stenting for Chronic Venous Obstructions.

PurposeDifferent techniques have been described for stenting of venous obstructions. We report our experience with two different confluence stenting techniques to treat chronic bi-iliocaval obstructions.Materials and MethodsBetween 11/2009 and 08/2014 we treated 40 patients for chronic total bi-iliocaval obstructions. Pre-operative magnetic resonance venography showed bilateral extensive post-thrombotic scarring in common and external iliac veins as well as obstruction of the inferior vena cava (IVC). Stenting of the IVC was performed with large self-expandable stents down to the level of the iliocaval confluence. To bridge the confluence, either self-expandable stents were placed inside the IVC stent (24 patients, SECS group) or high radial force balloon-expandable stents were placed at the same level (16 patients, BECS group). In both cases, bilateral iliac extensions were performed using nitinol stents.ResultsRecanalization was achieved for all patients. In 15 (38 %) patients, a hybrid procedure with endophlebectomy and arteriovenous fistula creation needed to be performed because of significant involvement of inflow vessels below the inguinal ligament. Mean follow-up was 443 ± 438 days (range 7–1683 days). For all patients, primary, assisted-primary, and secondary patency rate at 36 months were 70, 73, and 78 %, respectively. Twelve-month patency rates in the SECS group were 85, 85, and 95 % for primary, assisted-primary, and secondary patency. In the BECS group, primary patency was 100 % during a mean follow-up period of 134 ± 118 (range 29–337) days.ConclusionStenting of chronic bi-iliocaval obstruction shows relatively high patency rates at medium follow-up. Short-term patency seems to favor confluence stenting with balloon-expandable stents.

Deep venous thrombosis and postthrombotic syndrome: invasive management.

Invasive management of postthrombotic syndrome encompasses the two ends of the deep vein thrombosis spectrum, patients with acute iliofemoral deep vein thrombosis and those with chronic postthrombotic iliofemoral venous obstruction. Of all patients with acute deep vein thrombosis, those with involvement of the iliofemoral segments have the most severe chronic postthrombotic morbidity. Catheter-based techniques now permit percutaneous treatment to eliminate thrombus, restore patency, potentially maintain valvular function, and improve quality of life. Randomized trial data support an initial treatment strategy of thrombus removal. Failure to eliminate acute thrombus from the iliofemoral system leads to chronic postthrombotic obstruction of venous outflow. Debilitating chronic postthrombotic symptoms of the long-standing obstruction of venous outflow can be reduced by restoring unobstructed venous drainage from the profunda femoris vein to the vena cava.

A histological and functional description of the tissue causing chronic postthrombotic venous obstruction

BackgroundPostthrombotic intraluminal tissue causing postthrombotic syndrome (PTS) has not been well described. This study defines its histological characteristics and assess whether tissue function evolves over time. MethodsSpecimens from 18 common femoral veins (CFV) from 16 patients obtained during CFV endovenectomy and iliocaval recanalization were examined. Phase 1 used hematoxylin and eosin and Masson’s trichrome stains for collagen, immunohistochemical, and Von Kossa stains. Phase 2 examined young (≤ one year) and mature (≥10years from acute DVT) specimens to evaluate evolution of endothelial function. Antibodies to four biomarkers were used to examine specific functions of endothelial cells lining neovessels and recanalization channels (RC). ResultsPhase 1: Specimens demonstrated 80-90% of collagen type I, 10-20% of collagen type III, and dystrophic calcification. Neovessels and RC were in close proximity to each other. Thrombus and smooth muscle cells were absent, but white blood cells were present. Phase 2: VEGFR2 receptor uptake was more abundant in neovessels than RC and more prominent in younger specimens. Neovascular, nonchannel cells were observed more frequently in young specimens. CD-31 was similar in young and mature specimens. TIE-2 and von Willebrand factor antibodies had greater uptake in mature specimens. ConclusionTissue causing chronic postthrombotic venous obstruction is predominantly type I collagen. Neovascularization and recanalization occur in close proximity. The biomarker for neovascularization and angiogenesis (VEGFR2) was more prominent in young specimens whereas TIE-2, a stabilizing biomarker and vWF were more frequently observed in mature specimens.

Venous In-stent Thrombosis Treated by Ultrasound Accelerated Catheter Directed Thrombolysis

Stent placement in the venous system is an increasingly used treatment modality in chronic venous obstruction and as additional treatment after thrombolytic therapy in ilio-femoral deep vein thrombosis (DVT). Experience in treating in-stent thrombosis with ultrasound accelerated catheter directed thrombolysis (UACDT) is reported. A retrospective analysis of patients treated for venous stent occlusion, after percutaneous transluminal angioplasty (PTA) and stent placement for either chronic venous occlusive disease or persistent vein compression in patients with acute DVT was performed. Duration of occlusion and suspected clot age were assessed using patient complaints and typical findings on duplex ultrasonography (DUS). DUS and venography were used to assess patency and to determine the cause of re-occlusion. Acute treatment of occlusion was by UACDT. Additional procedures included PTA, stent placement, and creation of an arteriovenous (AV) fistula. Eighteen patients (median age 43 years; 67% male), treated for occluded stent tracts with UACDT between January 2009 and July 2014, were identified. Indications for initial stenting were treatment of chronic venous obstructive disease (12 patients) and treatment of underlying obstruction after initial thrombolysis in acute DVT (six patients). Technical success was achieved in 11/18 (61%) patients. Primary patency in 8/11 patients was 73% at last follow up (median follow up 14 months [range 0-41 months]). Additional treatments after successful lysis were re-stenting (seven patients) and creation of an AV fistula (six patients). Treatment with UACDT of recently occluded stent tracts is feasible and effective. Recanalization of the stent tract can be achieved in most cases. Additional interventions were frequently used after successful UACDT treatment. Suboptimal stent positioning caused the majority of the stent occlusions.

Combined Transmesenteric and Transhepatic Recanalization of Chronic Portal and Mesenteric Vein Occlusion to Treat Bleeding Duodenal Varices

Two patients presented with bleeding duodenal varices secondary to mesenteric and portal vein chronic occlusion. After a failed transhepatic recanalization, a combined transmesenteric and transhepatic approach was used to recanalize the chronic portal and mesenteric venous obstruction. The occluded segment was treated with transmesenteric stent placement in one patient and stent placement and coil embolization of varices in the second patient. Follow-up imaging and endoscopy showed decompression of the duodenal varices in both patients and absence of further bleeding episodes.

The new era of vascular interventions: The venous side

In spite of the huge advances in endovascular management of arterial diseases, surgery remained for a long time the only available option for treating veins. The situation has changed dramatically since the introduction of minimally invasive interventions for treating superficial as well as deep venous diseases. To review the recent advances in venous imaging and interventions for treatment of varicose veins, venous outflow obstruction and deep vein thrombosis. Reviewing available literature providing evidence for the new technologies available for treating: 1- Chronic Venous Disease (including superficial varicose veins and deep venous obstructions). 2- Deep Vein thrombosis (DVT). RCTs showed that ultrasound-guided endovenous thermal or chemical ablation of superficial varicose veins are as effective as surgical ligation and stripping with the additional advantages of being minimally invasive, with less complications and more patient satisfaction, potential treatment in out-patient setup and early return to work. Stenting of chronic deep venous obstruction is safe, effective in improving symptoms and treating venous leg ulcers. Catheter-directed thrombolysis and pharmaco-mechanical thrombolysis are both effective in treating acute DVT and reducing post-thrombotic manifestations. Current evidence shows that management of venous diseases is now shifting towards minimally invasive interventions with very promising results. Given the lots of research work done in the field nowadays and evolving technologies provided by manufacturers, it will soon be the standard of practice offered for patients with chronic venous disease.

The incidence of contralateral iliac venous thrombosis after stenting across the iliocaval confluence in patients with acute or chronic venous outflow obstruction.

Percutaneous transluminal angioplasty with stenting of the iliac veins is the method of choice to treat patients with symptomatic lower extremity venous outflow obstruction. The optimal method of performing this technique remains to be solved, however. One question in particular is that when braided stainless steel stents (Wallstents; Boston Scientific, Natick, Mass) are used, should these venous stents extend into the vena cava or should they stop short of this for fear of causing thrombosis of the patient's normal contralateral iliofemoral vein? It has been our practice to extend our venous stents significantly into the vena cava to coapt with the inferior vena cava (IVC) wall in the majority of patients with disease of the common iliac vein at the iliocaval junction. The aim of this study was to assess whether this placement led to thrombosis of a normal contralateral common iliac vein. We retrospectively reviewed prospectively collected data from 2008 to 2012 in patients with symptomatic acute or chronic iliocaval venous obstruction who underwent percutaneous angioplasty and stenting at our institution. Data were collected by use of the American Venous Forum venous stent database variables. Stent patency rates and the incidence of contralateral iliac vein thrombosis were analyzed. In 65 patients (median age, 48years; range, 15-80years), 200 iliocaval stents were placed. Of these patients, 41 received ipsilateral stents that extended into the IVC and completely across the contralateral common iliac vein orifice; 39 (95%) of these had venous outflow obstruction as a result of thrombotic disease. In 22 patients (54%), post-thrombotic disease involved the IVC. All patients had stents that extended into the IVC, crossing the normal contralateral iliac vein orifice completely. Most patients (97.5%) were maintained by full anticoagulation with warfarin or low-molecular-weight heparin. Four patients (9.7%) suffered new thrombosis of the nonstented contralateral iliofemoral vein; two patients had initial involvement of the IVC, and three were totally noncompliant with their postoperative anticoagulation. Thus, 2.4% of compliant patients had new contralateral thrombosis after stenting across a normal contralateral common iliac vein and into the vena caval wall. In this select patient population, univariate analysis of patient compliance with the postoperative anticoagulation strategy showed a strong correlation with postoperative contralateral iliofemoral venous thrombosis (P= .0004). From these data, it appears that stenting across the iliocaval confluence can be done safely in the majority ofpatients maintained with therapeutic anticoagulation. Inpost-thrombotic patients, however, stenting across the iliocaval confluence can result in a small number of new contralateral thromboses, more often if the patients are noncompliant with anticoagulation after stenting. Current stent technology limits the ability of practitioners to treat common femoral venous obstruction precisely. Future stent development is likely to eliminate the need to cross the iliocaval confluence and risk contralateral venous thromboses.

Aberrant Centrizonal Features in Chronic Hepatic Venous Outflow Obstruction

Chronic hepatic venous outflow obstruction is characterized by centrizonal scarring but may also display features that can lead to portal tract mimicry and misdiagnosis as biliary disease, especially given elevated cholestatic liver profiles in these patients. However, these histopathologic features have not been systematically described. We graded the numbers of centrizonal arterioles, ductules, keratin 7+ hepatocytes, CD34+ microvessels, and capillarized sinusoids in 61 cases of chronic venous outflow obstruction and assessed changes in metabolic zonation by glutamine synthetase staining. Centrizonal arterioles and ductules were present in 82.0% and 72.1% of cases, respectively, and correlated with fibrosis. Centrizonal CD34+ microvessels and sinusoidal capillarization were closely associated and present in 25 (92.6%) and 26 (96.3%) of 27 cases, respectively. Centrizonal capillarized sinusoids and microvessels, which were present in all cases with advanced fibrosis, were demonstrated in 90% and 80% of the cases without significant fibrosis, respectively. The results suggest that capillarization and/or microvessel formation precede and may contribute to centrizonal scarring, whereas arterialization likely reflects vascular remodeling associated with progressive fibrosis. Centrizonal ductules were often immature, being either keratin 7+/keratin 19- (36.4%) or keratin 7-/keratin 19- (10.0%). Centrizonal keratin 7+ intermediate-phenotype hepatocytes were present in 25 (92.5%) of 27 cases. Lastly, 22 (91.7%) of 24 cases showed loss of metabolic zonation, with reversed zonation in 2 (8.3%) cases. Together, the findings indicate that vascular and lobular reorganization in chronic venous outflow obstruction may result in mimicry of central zones as portal tracts. Recognition of these changes is essential to prevent misdiagnosis of this condition as biliary tract disease.

Treatment of IVC Thrombosis in Patients Undergoing Iliocaval Stenting for Acute or Chronic Venous Obstruction.

Treatment of IVC Thrombosis in Patients Undergoing Iliocaval Stenting for Acute or Chronic Venous Obstruction.