Previous studies suggest that blood clots lead to permanent damage of the leg veins. When a blood clot forms, the body’s reaction (called “inflammation”) harms the one-way vein valves that normally keep blood flowing in the correct (upwards) direction, leading to backflow (“reflux”). Even with blood-thinning drug treatment, some clot often remains in the leg veins and may cause complete or partial blockage (“obstruction”) of blood flow. In the long run, the vein blockage and backflow lead to abnormally increased blood pressure in the veins, especially when a patient is upright or walking (this is called “ambulatory venous hypertension”), which in turn leads to the symptoms and signs of the Post-Thrombotic Syndrome (PTS).
The Open Vein Theory postulates that a patient’s health is likely to be better if the large veins that drain blood flow from the leg are open and flowing properly. This theory forms the basis for believing that image-guided treatments may help patients with DVT and PTS. In the setting of acute (new) DVT, this raises the question of whether active clot-busting treatments can prevent or reduce PTS by quickly restoring blood flow and preventing vein damage (see our work on the ATTRACT Study. For patients with chronic (old) DVT who have PTS, this also raises the question of whether eliminating the vein blockage and backflow can reduce patients’ symptoms and disability (see our current C-TRACT Study that is evaluating this question).