7. If a deep venous thrombosis or other vascular event has required medical or surgical intervention in the past year, patients must either: a) be on a stable dose of anticoagulant therapy (i.e., Coumadin and/or Heparin) for at least three weeks or b) have completed anticoagulant therapy at least three months prior to registration with radiographic confirmation that thrombosis is resolved. Prophylactic anticoagulant therapy for indwelling catheters is acceptable.