Association between the degree of iliac venous outflow obstruction by intravascular ultrasound and lower limb venous reflux.

OBJECTIVE:The present study aims to evaluate the association between the degree of iliac venous outflow obstruction (IVOO) identified by intravascular ultrasound (IVUS) and venous reflux presentation in the lower limbs on duplex ultrasound (DU). METHODS:Patients with bilateral chronic venous insufficiency, CEAP (clinical-etiology-anatomy-pathophysiology) C3 to C6, and a visual analog scale score for pain >5 underwent DU for reflux evaluation of the deep venous system (reflux ≥1 second); superficial system, great saphenous vein, and small saphenous vein (reflux ≥0.5 second); and perforator system (reflux ≥0.35 second). All patients underwent IVUS in the iliac venous territory. The area of the impaired venous segments was categorized as obstruction <50% (category 1), 50% to 79% (category 2), and ≥80% (category 3). The venous clinical severity score and reflux multisegment score (RMS) were assessed. RESULTS:A total of 51 patients (n = 102 limbs; age, 50.53 ± 14.5 years; 6 men) were included. The predominant clinical severity CEAP class was C3 in 54 of 102 limbs (52.9%). The mean VCSS was 14.3 ± 6.7. A severe RMS (≥3) was registered in 63.4% of the limbs. Of the 102 limbs, 51 (50%) presented with category 1, 27 (26.5%) with category 2, and 24 (23.5%) with category 3. Previous deep vein thrombosis (DVT) was associated with critical obstruction (odds ratio [OR], 3.65; 95% confidence interval [CI], 1.29-10.38; P = .015). The superficial and perforator venous systems had no association with the degree of IVOO. Deep venous reflux (DVR) had a significant association with significant IVOO (obstruction ≥50%; OR, 6.44; 95% CI, 2.19-18.93; P = .001) and critical IVOO (obstruction ≥80%; OR, 4.57; 95% CI, 1.70-12.27; P = .003) and a significant linear association with the IVOO degree and reflux in the femoral veins (P < .001) and popliteal vein (P = .008). Significant lesions were significantly more likely to develop in the left limb (OR, 5.76; 95% CI, 2.46-13.50; P < .001). After multivariate analysis, DVR remained a predictor for significant and critical obstruction (P < .003 and P < .012, respectively). Left limb and previous DVT remained as predictors for IVOO of ≥50% and ≥80% (P < .001 and P = .043, respectively). CONCLUSIONS:We found a significant linear association between the degree of IVOO and reflux in the deep venous system on DU. Limbs with DVR, a severe RMS, loss of respiratory variation on DU, and previous DVT were more likely to be affected by IVOO of ≥50%, especially with left leg involvement.