I had 12 sessions of ECT over a 4 week period. I only had 2 side effects - it made me nauseous which my pdoc controlled with some medication and short-term memory loss. Th memory loss was odd because you don't know what you've forgotten until someone points it out.
ECT was successful for me. It did take the 12 sessions and some time after I was released from the hospital, but it did help pull me out of a deep depression.
Good luck with your treatment.