Abstract
Functional outcomes following catheter-based iliac vein stent placement
Vasc Endovasc Surg 2013;
The authors’ objectives of this study were to access midterm outcomes and functional quality of life among patients treated with iliac vein stenting. Thirty-two patients (33 limbs) underwent iliac vein stent placement during a 7–year period. Seventy-two percent were females (average age 43 years); 78% of the patients were diagnosed with acute DVT, 89% of which occurred in the left leg; 92% of the acute DVT patients underwent catheter-directed thrombolysis. All patients treated with thrombolysis and stent placement presented with pain and edema in the affected limb. One-year primary assisted primary, and secondary patencies were 75%, 96%, and 96%, respectively. Freedom from reintervention at 1 year was 83%. Treatment was associated with a reduction in pain (91% vs. 6%, P < 0.001) and edema (97% vs. 12%, P < 0.001). Patients (mean follow-up of 29 months) reported to be at their pre-DVT functional status. The authors conclude that by prompt catheter-directed thrombolysis, and iliac vein stent placement, patients can anticipate good functional recovery with decreased pain, decreased edema, and high likelihood of returning to work.
Iliofemoral venous stenting extending into the femoral region: initial clinical experience with the purpose-designed Zilver Vena stent
J Cardiovasc Surg (Torino) 2013;
The authors’ intent of this study was to assess the early clinical experience with the Zilver Vena stent in treating patients with iliofemoral venous obstruction. Twenty patients (12 women; mean age of 59 ± 17 years) treated for iliofemoral vein obstruction with 1-year follow-up were retrospectively reviewed. Seventy percent of patients presented with acute obstruction, of which 50% had an active malignancy. Twenty-five percent of the patients were diagnosed as having May–Thurner Patency was established venographically at procedure end, and was evaluated with Duplex ultrasound in follow-up. Flow was re-established through the obstructed venous segment in all patients; however, three patients experienced early stent thrombosis (<30 days). The patency rate was 85% (17/20 patients). Clinical improvement was demonstrated by decreased leg swelling (17/20) in patients. The authors conclude that the Zilver Vena stent performed favorably; however, these results need to be confirmed in multicenter studies.
Ovarian vein syndrome during pregnancy – diagnostic and treatment
Akush Ginekol (Sofiia) 2013;
The authors studied the presence of ovarian vein syndrome in second trimester pregnancy and safety and effectiveness of stents insertion in symptomatic hydronephrosis. Ovarian vein syndrome is a ureteral obstruction secondary to ovarian vein dilatation. In 2007–2011, 66 women were hospitalized and presented with acute pyelonephritis and painful hydronephrosis. Laterality was established: 92% right, 3% left and 5% with both sides. On the ultrasound Doppler investigation, 61 cases with right hydronephrosis were with varicose right ovarian vein anomalies, which caused unilateral ureteral obstructions. Using ultrasound guidance, 66 retrograde ureteral stents were successfully placed under local anesthesia. In 66 patients with urinary infection, patients’ fever defervesced in the first 24–48 h after the placement of the ureteral stents. The majority of cases are diagnosed during pregnancy, with a 90% predominance on the right side. The authors conclude that ureteral stenting is an effective, simple and safe method in treating symptomatic hydronephrosis during pregnancy.
Indications for platelet aggregation inhibitors after venous stents
Phlebology 2013;
In large series early stent occlusions and late re-stenosis are reported. Meissner wrote, “Although most of these appear related to technical factors, there is likely a role for pharmacological adjuncts in maintaining stent patency.” He continues to state that the use of anticoagulants and antiplatelet agents is largely based on extrapolation from arterial interventions. The author concludes: “Although lacking substantial evidence demonstrating efficacy, the use of adjunctive antiplatelet agents in stents placed for primary lesions and consideration of anticoagulation for high-risk post-thrombotic lesions appears to be reasonable.”
Editor's note: Presently, antiplatelet agents use after venous stenting for non-thrombotic lesions has consensus. But why?
Platelet recruitment to venous stent thrombi
J Thromb Thrombolysis 2013;
Thrombosis following venous stent placement is a morbid clinical outcome. Whether to target platelets or coagulation factors for venous stent thromboprophylaxis remains unclear. The authors sought to determine whether integrin α(IIb)β3 antagonism with lamifiban would inhibit platelet recruitment to venous stent thrombosis. Anti-thrombotic efficacy was compared between venous and arterial circulations. Pigs received either lamifiban (0.2 mg/kg bolus plus 0.2 mg/kg/h infusion; n = 6) or saline (n = 12). (Lamifiban is an intravenously administered, selective, reversible, nonpeptide glycoprotein IIb/IIIa receptor antagonist which inhibits platelet aggregation and thrombus formation by preventing the binding of fibrinogen to platelets.) Carotid arteries were crush injured and then harvested 30 min later to provide an assessment of antithrombotic efficacy in the arterial circulation. Iliac venous stents were then deployed and thrombi allowed to propagate for 2h before harvesting. Platelet deposition was measured by scintillation detection of autologous (111)In-platelets. Venous thrombi were quantified by weight and compared to platelet, Von Willebrand factor (VWF) and fibrinogen content. Arterial platelet deposition (×10(6)/cm(2)) was reduced >80% by lamifiban (398 ± 437) compared to controls (1540 ± 883; p < 0.005). Lamifiban also reduced venous thrombus platelet deposition (139 ± 88 vs. 281 ± 167), however did not prevent thrombosis. In control animals, venous stent platelet deposition correlated with plasma fibrinogen content (R(2) = 0.29; p = 0.03). Fibrinogen content correlated directly with venous stent platelet deposition (p = 0.03) but not thrombus weight. Neither venous platelet deposition nor thrombus weights varied by VWF content. Platelet recruitment to venous stent thrombi occurs in part through the integrin α(IIb)β3 receptor. The authors conclude that unlike arterial thrombosis, inhibition of this receptor is insufficient to prevent venous stent thrombosis.
Endovascular treatment of iliofemoral chronic post-thrombotic venous flow obstruction
J Vasc Surg: Venous Lym Dis 2014;
From 2009 to 2012, these Spanish investigators examined 41 limbs in 36 patients with post-thrombotic obstruction of iliofemoral vein. The procedure was successful in 39 limbs (95%) with no mortality and low morbidity. Thrombotic events occurred in nine limbs (23%) during the follow-up period. At 33 months, primary, assisted-primary, and secondary cumulative patency rates were 74%, 87%, and 89%, respectively. The main risk factor associated with stent occlusion was the severity of thrombotic disease. All postoperative thrombotic events occurred in occluded veins; no previously stenotic veins presented any complication (P = 0.04). The presence of thrombophilia, stent brand, and stent extension into the common femoral vein was not significantly associated with stent thrombosis. After surgery, the mean revised VCSS and Villalta scores improved substantially (P < 0.0001). The cumulative rate of revised VCSS improvement was 89% at 33 months. Clinical improvement was observed despite deep venous system reflux remaining uncorrected.
Validation of the Villalta scale in assessing post-thrombotic syndrome using clinical, duplex, and hemodynamic comparators
J Vasc Surg: Venous Lym Dis 2014;
Limited data exist as how the Villalta scale (VS) compares against generalized assessment tests in defining the severity of post-thrombotic syndrome (PTS). The aim of this study from the UK was to compare the VS against the Venous Clinical Severity Score (VCSS), the C of the CEAP classification, the Venous Segmental Disease Score (VSDS), and the Venous Filling Index (VFI) of air plethysmography. Baseline data generated from a recent single-center prospective clinical trial comparing graduated elastic compression stocking performance on 40 legs in 34 patients with PTS were analyzed. All the legs had PTS defined as persisting leg symptoms/signs at least 6 months after a deep vein thrombosis with evidence of deep venous obstruction and/or deep venous reflux on duplex ultrasound. Unadjusted VS scores were used so patients with ulceration with a VS <15 were not automatically upgraded to a score of 15. The VS had a highly significant and moderate-to-good correlation (Spearman) with the VCSS (r = 0.609; P < 0.0005) and the C of CEAP (r = 0.556, P < 0.0005). When the VFI was used as a hemodynamic benchmark, the VS correlation outperformed the other assessment tests (r = 0.499; P = 0.001). However, the VCSS correlation with the VFI was also significant (r = 0.480; P = 0.002). Surprisingly, the VSDS did not correlate with any assessment tests. No correlation could be detected within the VS between patient symptoms and their clinical signs. Correlations between the VS and the VCSS (r = 0.775) and C class (r = 0.779) improved when the VS patient-reported part was excluded. The authors concluded that the VCSS and the C of CEAP may also be useful in the assessment of PTS severity, and the VFI may provide a clinically meaningful hemodynamic evaluation. However, using the VFI as a reference, there was no essential difference between the VS and the VCSS.
National trends in utilization of inferior vena cava filters in the United States, 2000–2009
J Vasc Surg: Venous Lym Dis 2014;
This multicenter, retrospective cross-sectional study used the Nationwide Inpatient Sample Database (2000–2009) to look at IVC filter placement. The number of IVC filters placed in the US increased by 234% over a decade, from 56,380 in 2000 to 132,049 in 2009; 84.7% of patients had a pulmonary embolism or deep venous thrombosis, 94.6% of IVC filters were placed in urban hospitals. The largest number of IVC filters was placed in the South, followed by the Northeast, Midwest, and Western regions (38.7%, 25.8%, 22.4%, and 13%, respectively). Adjusting for other patient and hospital factors, independent predictors of IVC filter placement were year, hospital size, location, teaching status, patient age group 50 to 79 years, insurance status, and urgency of admission. The investigators concluded that the use of IVC filters has dramatically increased over the last decade in the US, with variation in utilization based on patient and hospital characteristics. The largest utilization of IVC filters was among patients aged 50–79 years, Medicare recipients, and the Southern region of the US. The majority of patients receiving IVC filters have a diagnosis of pulmonary embolism or deep venous thrombosis.
Hemodynamic changes in the femoral vein with increasing outflow resistance
J Vasc Surg: Venous Lym Dis 2014;
Measurements of outflow resistance (OR) impeding venous return may be helpful to select patients for intervention and to assess the impact of intervention. A proof-of-concept study is presented by a group from the UK in healthy volunteers where OR is quantified using duplex assessment of the femoral vein (FV) at mid-thigh following predetermined inflation pressures with a high thigh tourniquet. Twenty-two consecutive subjects (15 males) without evidence of venous disease by clinical and duplex examination were studied. Subjects were examined standing with the test leg nonweight-bearing, resting gently on the floor. A 26-cm-wide calf cuff was attached to an intermittent pneumatic compression device that delivered three calf compressions per minute at 120 mm Hg. A high thigh cuff, 12 cm wide, was inflated just before each calf compression in multiples of 20 mm Hg, from 0 to 120 mm Hg, to provide a standard OR. FV waveform parameters were recorded using duplex beneath each thigh-cuff inflation pressure and repeated three times. OR was calculated using change in pressure (P2-P1)/Flow (Q). Pressure P2 was 120 mm Hg minus the additional height to the duplex transducer. P1 was assumed to be zero. Flow was cross-sectional area (π × diameter [d]2/4) × velocity. The velocity parameters chosen were peak velocity (PV), time-averaged mean velocity (TAMV), and TAMV from start to peak. Peak velocity, TAMV, and TAMV to peak all decreased significantly (P < 0.0005; Friedman) with increasing thigh cuff pressure with P < 0.0005 correlations (Spearman) of r = 0.842, r = 0.488, and r = 0.744, respectively. Furthermore, increasing thigh cuff pressure at 0, 20, 40, 60, 80, 100, and 120 mm Hg also caused a gradual and significant increase in median (interquartile range) OR at 27 (19–34), 30 (21–12), 30 (23–44), 40 (26–17), 46 (32–51), 61 (38–71), and 79 (45–134) resistance units, respectively (P < 0.0005; Friedman, and r = 0.516; Spearman). Higher baseline (innate) OR values were found in taller (P = 0.002) and heavier (P = 0.043) subjects. The authors concluded that hemodynamic velocity parameters in the FV attenuate progressively with increasing venous obstruction. OR can be quantified using duplex measurements when they are substituted into equations of fluid mechanics. Optimization of this novel technique, which requires an IPC outflow challenge test, may provide useful information in the assessment and treatment of patients.