Hello Stuart,
If you have just started taking it, has the dose been checked, or have you been told how to check the dose is correct? I think you must talk to your doctor or specialist to make sure, as you probaly know, if its to high, then your blood will not clot fast enough, and if its too low, it may clot as a result of your condition.
I know that balancing teh doseage can be difficult, my father bless his soul, also had to use it, it he had to maek regular visits to teh doctor to check the doseage.
Sadly I am also about to go ont a lifetime of wafarin, as I need a replacement heart valve.
So please kep us posted.