Preliminary study of the hemodynamics of iliac venous compression syndrome using magnetic resonance imaging.

Abstract

OBJECTIVE\nIn clinical practice, the degree of iliac vein stenosis is often inconsistent with chronic venous disease (CVD) symptoms. Clinical studies evaluating hemodynamic changes associated with iliac vein stenosis are currently lacking. Magnetic resonance imaging (MRI) can noninvasively provide hemodynamic information. This study assessed the degree of stenosis associated with iliac venous compression syndrome (IVCS) and the relationships between IVCS-induced, MRI-determined hemodynamic changes and lower limb symptoms.\n\n\nMETHODS\nStenosis severity, collateral vessels, and flow rate differences between the common and external iliac veins secondary to iliac vein stenosis were measured by MRI in 69 CVD patients. Villalta scores were used as a measure of symptom severity in all patients, and percent change in Villalta score was used as a measure of symptom improvement in patients who received iliac vein stents. Symptom severity in all patients, in a subgroup of patients with iliac vein compression (affected limbs) and in a group of patients with unilateral iliac vein compression treated with stents was correlated with stenosis, differences in external and common iliac vein flow rates [< 0 ml/s group (indicating that stenosis-induced decreased common iliac vein flow) and ≥ 0 ml/s groups] and stenosis-induced collateral vessel formation.\n\n\nRESULTS\nIliac vein stenosis severity and flow rate differences in all affected limbs were correlated with the Villalta scores of the affected limbs (stenosis: r = 0.38, P < 0.001, n = 95; flow rate difference: r = -0.44, P < 0.001). In the unilateral compression subgroup, stenosis severity, differences in flow rate, and collateral vessels were not associated with significant changes in contralateral symptoms. In the endovascular treatment subgroup, both lower limbs exhibited significant improvement after stent implantation (affected limb: symptom remission 64.6% ± 18.2%, n = 15; contralateral limb: symptom remission 49.1% ± 29.1%, n = 11). Symptom remission was higher in patients with decreased iliac vein flow in the affected limbs (< 0 ml/s group: 74.6 ± 16.4%, n = 7; ≥ 0 ml/s group: 52.2 ± 16.6%, n = 6; P = 0.032).\n\n\nCONCLUSIONS\nIliac vein stenosis, the presence of collateral vessels, and decreased flow rate due to stenosis were significantly correlated with lower limb symptom severity. Endovascular treatment yielded good outcomes in patients with stenosis > 50%. A decreased iliac venous flow rate could indicate a better response to stent implantation and could be used in diagnosis and in guiding decisions to treat iliac venous compression.