Treatment is generally symptom-based. What kinds of treatments have you tried? What symptoms are you struggling with?
Ritalin isn't normally considered a first line of treatment. You may find that Florinef or Midodrine do more to alleviate your symptoms. That being said, I take Ritalin every four hours. As for the effects wearing off throughout the course of treatment, I've been told that taking a two week break every year can sort of "reset" your system. I've yet to do that myself, but may sometime in the near future.
As for implantable devices, the usefulness of a pacemaker in Dysautonomia is an ongoing debate amount specialists. If your syncope events are caused by a drop in blood pressure first, a pacemaker cannot correct that. If some of your syncope episodes are caused by a sudden drop in heart rate however, your Cardiologist may opt for a pacemaker. The decision really depends on you, and your specialist.
Don't know of any implantable devices. Ritalin effect can wear off for some people, as can Adderall. Provigil is supposed to work the same way without building up a tolerance, but I haven't personally tried it yet. The best place to look for treatment options is the upper right side of your screen where it says "Health Pages". Welcome to the group!