Neovascularization in acute venous thrombosis

Area of Science:

• Vascular Medicine
• Interventional Radiology
• Diagnostic Ultrasound

Background:

• Venous thrombus formation can lead to complications, but the development of arteriovenous fistulas (AVFs) within thrombi is an under-described phenomenon.
• Understanding the characteristics of AVF formation in venous thrombus is crucial for accurate diagnosis and management.

Purpose of the Study:

• To describe the phenomenon of arteriovenous fistula (AVF) formation within venous thrombus.
• To characterize the ultrasound findings, including flow patterns and resistivity indices, associated with AVF in thrombosed veins.

Main Methods:

• Patients referred for deep venous thrombosis evaluation underwent duplex ultrasound scanning.
• Flow patterns, resistivity indices, and vessel characteristics were assessed in thrombosed veins and adjacent arteries.
• Exclusion criteria included trauma, hemodialysis access, endovenous ablation, known AVF, or inflammatory conditions.

Main Results:

• Twenty-two patients presented with AVF flow within thrombosed veins (deep and superficial).
• Perivenous vessels feeding the AVF were identified, with multiple flow channels within the thrombus in most cases.
• Flow patterns within the thrombus were indicative of fistula flow (mean resistivity index 0.48), with unaffected adjacent main arteries and no systemic symptoms.

Conclusions:

• Neovascularization with AVF flow occurs within venous thrombi, originating from perivenous arteries.
• These AVFs have variable morphology, including multiple flow channels and lengths.
• The etiology, natural history, and clinical significance of AVF formation in venous thrombus remain to be elucidated.