High-resolution duplex ultrasound imaging proves a high incidence of an arterial neovascularization phenomenon associated with venous thrombosis

Introduction. - We have recently observed an interesting phenomenon of prominent arterial neovascularization (ANV) within the thrombus and vein wall of patients with major venous thrombosis, sometimes intense enough to mimic small arteriovenous fistula. A prospective study was therefore conducted in 50 patients to further characterize this process. Aims. - We sought to determine the incidence of ANV; to characterize the process in more detail; and to determine whether there was an eventual recanalization of the thrombosed vein and favorable clinical outcome Methods. - All patients presenting with lower-extremity venous thrombus were prospectively imaged with Philips HDI 5000 and IU22 ultrasound systems using a standard protocol, including spectral and color Doppler analysis. Blood flow patterns in and around the thrombus were closely observed and recorded. In each patient, the phenomenon was assigned a grading from 0 to III according to prominence and penetration of the neovascularization process into the thrombosed vein. Results. - A total of 50 consecutive patients (age range; 35-80 years) were included in the study. 32 patients had DVT and 18 patients had superficial venous thrombus (SVT). ANV was observed as small vessels demonstrating a low-resistive arterial signature appearing predominantly on the vein wall and/or within the thrombus. The typical vessel diameter was 0.3-3.0 mm. ANV was present in 80% of patients examined and in 97% of cases with thrombus aged less than a year old. It was more common with SVT (100%). The process was most prominent at the 2-4 month interval after venous thrombosis. Conclusion. - There is a process of neovascularization that commonly occurs in association with venous thrombus. This was detected in 97% of patients with thrombus less than a year old. ANV appears to be a normal component of the recanalization process and may result from an inflammatory reaction. Further studies will be required to determine if the grade of this process can be correlated with favorable long-term outcome.