High-Resolution Duplex Ultrasound Imaging Proves a High Incidence of an Arterial Neovascularization Phenomenon Associated with venous Thrombosis

Abstract

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.

Imaging of deep vein thrombosis

“…Duplex scanning can demonstrate the recanalization of an organizing DVT, which may continue for up to 1 year29. Recently, high‐resolution duplex techniques have even imaged the development of arterial neovascularization that occurs as part of this process30. It is sometimes important to determine whether a new DVT has developed in a post‐thrombotic limb when the patient develops more pain or limb swelling.…”

Unusual Presentation and Identification of a Post-traumatic Arteriovenous Fistula Identified with the Use of Duplex Ultrasonography

“…2 The unusual findings of multiple venous collaterals with arterial Doppler signals within the thrombus and vein wall in this case suggested an arteriovenous fistula. In one recent report, in which the authors had initially inspired the technologists and led to the diagnosis of this case, 3 the author described an interesting finding of arterial neovascularization within a venous thrombus (less than 1 year old) and vein wall of patients with proximal deep vein thrombosis, sometimes marked enough to appear as small AVF. In our case, subsequent ultrasound examinations revealed Doppler waveform characteristics that were suspicious for an AVF.…”

A Case of Mistaken Identity: When a Deep Vein Thrombosis is not a Thrombosis

“…10 In the past, this may have been considered sufficient evidence to distinguish tumor from thrombus. 11 However, in recent times, vascularity of thrombi has been reported as a normal finding in DVT presentation 5 and low resistant arterial waveforms in acute DVT's have been described as “neovascularization.” 5 In addition, a description of flow that is low resistant and arterialized as “fistula” flow has also been described. 12 The authors of study have suggested differentiating between thrombus and tumor flow on the basis of velocity and pulsatility, with thrombus flow demonstrating very low velocity, and a lower resistive index (RI) than tumor flow.…”

“…Several investigators have discussed the diffi culty of distinguishing intravascular tumors from thrombus. [4][5][6] Therefore, their diagnosis can be diffi cult, delayed or missed, especially because they comprise such a low percentage of all patients with venous disease. This is especially true if the tumor is confi ned to the vessel and has not extended out of the lumen, making the symptoms, physical and ultrasonic examination even more closely aligned with that of a thrombotic event.…”

“…6 Low-velocity thrombus fl ow has not been duplicated in other studies where high-velocity thrombus fl ow has been noted. 5 In relation to the RI, most thrombus fl ow studies have demonstrated a low RI with the thrombus, averaging just less than 0.5. 5,12 We found a RI of 0.46 in case 1, and an average RI of 0.56 in case 2; however, there was a range of RIs recorded in case 2, ranging from 0.45 to 0.65.…”