Unfortunately, you are correct about tPA and similar substances that might dissolve the clots. They all must be administered as soon as possible in the acute phase of embolization.
Surgical clot removal and vascular re-attachment is, as you indicated, based on the assessment of risk of surgery. As has been suggested of your father, not all persons with clots (Class IV and some Class III) are candidates for endarterectomy. Your father's physicians may have correctly assessed him as being either Class III or IV. Pre-operative evaluation of risk is crucial.
This is a rather specialized procedure and should be performed only by physicians who have had extensive experience with the procedure.
For my father who can not have surgery to remove blood clots in the lungs and warfarin, etc. have not worked.....is there anything else out there that can dissolve the clots? Since we have the same blood type could we do a blood transfusion if I have the enzyme he doesn't have to dissolve clots?
Thank you.