May-Thurner syndrome is not a disease but an anatomic variant where there is compression of the left iliac vein by the right common iliac artery. Patients usually present with a swollen, painful left leg. An iliac vein DVT is found on workup for left leg swelling.
The mainstay of treatment in the past was anticoagulation with heparin and Coumadin. This treated the clot but did not prevent valvular damage, which produced chronic leg edema. More recently, catheter-directed thrombolysis followed by angioplasty and stenting of the iliac vein has been used with some success.