In coma, there is the medullary depression (stage of agony). Spontaneous respiration and circulation cease i.e. vasomotor center. There is no full circulatory and respiratory support.
Assume you could stimulate and coordinate fully the autonomic nervous system of the heart. You know exactly which pacemaker cells and pathways are blocked in the particular coma patient. I have in mind Schumacher's case - where you have head injury. I think you should consider, in his case, the pressure of the head also if you can restore circulation and respiration artificially.
Some neurologists say that it is practically very difficult to wake a person if he has been in coma for six months. I would like to understand this. I think it is because of atrophy of muscles and probably something with atherosclerotic changes. However, I am still interested in your opinion about the theoretical situation - if you can restore heart and respiration centre, can the recovery start?
What are the limitations of restoring the function of the body by restoring the circulation and respiration i.e. vasomotor centers after long stay in coma?