Heterogeneity in Post-Thrombotic Vein Wall Remodeling

Abstract

Post-thrombotic (PT) vein wall remodeling after thrombosis begins early after thrombus deposition and may persist even after thrombus resolution. The chronic luminal changes that occur have not been well characterized in PT patients. This study was designed to assess the extent and variability of chronic venous wall remodeling in the lower extremities. This prospective controlled study evaluated PT adult patients who presented with deep venous thrombosis (DVT) of >6 months in common femoral, femoral, popliteal, and axial calf veins as diagnosed by duplex ultrasound. Patients with recurrent DVT in the ipsilateral limb, penetrating trauma, complete or partial luminal obstruction, synechiae, or any other conditions affecting venous architecture were excluded. Normal ipsilateral and contralateral limb segments were included as control measurements when available. In all segments, venous wall thickness was measured using real-time high-definition zoom with a high-resolution linear array transducer. Only ultrasound images obtained under the best acoustic window at multiple angles to avoid slice thickness and off beam artifacts with distinguishable venous wall segments were included. For each venous segment with a smooth luminal surface, three measurements were obtained and the average value was used. In instances in which the lumen/blood interface was not uniform but rather irregular, three additional measurements were obtained and averaged from the heterogeneous area. Twenty-five PT patients (95 PT segments and 75 nonaffected segments) and 32 control patients (332 segments) were evaluated. Mean vein wall thickness was significantly higher in both the smooth (0.8 mm) and heterogeneous segments (1.1 mm) in PT patients compared with controls (0.370 mm) for all segments (P < .001). Segments with heterogeneous thickness were seen in 72% of patients. These heterogeneous regions were 1.40× (range, 1.25-1.48×) thicker than immediately adjacent PT segments and 2.89× (range, 2.6-3.18×) thicker than corresponding controls (P < .001). This prospective preliminary study suggests that the vein wall thickness at the PT stage is significantly elevated. On the same limb, it is common to find both smooth and heterogeneous areas. Detection of the chronic luminal changes may provide useful information in treating patients never formally diagnosed with DVT for the following reasons: it may allow the administration of chemical prophylaxis when surgery is required; it may lower the patient's expectations when superficial vein treatment is performed; and it could encourage the use of compression stockings.