I seriously doubt that you have had a clot for 18 yrs continously. I have had 4 DVTs over the years. The treatment was admit to the hospital and IV heparin and on to coumadin. Subsequent dopplers have shown the clots to have been dissolved. I apparently have something in my blood chemistry that makes me prone to develop clots. 2 in lt leg and 1 in rt leg all due to trauma. Latest in lt arm due to many venipunctures with subsequent phlebitis & a clot formation associated with a surgery. With the exception of the 6 days I was off the coumadin before the surgery, I am on coumadin for life which keeps the situaion well controlled. I will have a doppler next week to see how the latest is dissolving. A prothrombin time is done every 4 - 6 weeks to monitor the situation.