One complication of deep vein recanalization is:

Damage to venous valves is a recognized complication of deep vein recanalization procedures. During the recanalization process, which aims to restore patency to previously occluded veins, the mechanical or thermal interventions can inadvertently harm the fragile structures of the venous valves. These valves play a critical role in maintaining unidirectional blood flow and preventing reflux in the venous system. When damaged, they can lead to chronic venous insufficiency, resulting in symptoms such as swelling, pain, and varicosities due to improper blood flow.

In contrast, while infection, increased blood flow, and thrombus formation can occur in association with vascular procedures, they are not as directly tied to the act of recanalization of deep veins as valve damage is. Infection, though a possible complication, is more a generalized risk of any surgical procedure rather than specific to recanalization. Increased blood flow can occur as a positive outcome after successful recanalization rather than a complication, and while new thrombus formation can happen in patients with a propensity for thrombosis, it is not a direct consequence of the recanalization process itself. Overall, the risk of valve damage highlights the importance of careful technique and patient selection in deep vein recanalization interventions.