I don't know if this is any help, but my chiropractor told me that my aching (not trembling) hands post surgery might very well have been due to the action of splaying my chest back during the surgery and thus misaligning or messing with the backbone and all the cushioning agents. I wonder if you have a pinched nerve in that area of your back. I'm assuming you had the full sternotomy. I actually just learned this, almost 3 years post-op. Hadn't had the guts to see a chiropratctor until now, and then of course the "new way" of adjusting is not to sit on top of the patient and crack their back forcefully, but rather a much much gentler way. Anyway, his mother had had AVR so we got to talking and when I mentioned that my back never hurt me after the surgery (and so many here have troubles in their backs or shoulders) but that my hands were weak and aching....he suggested that it was my back which was probably out which contributed to that. Lasted a good 3 months or more, too. Should have gone to see him sooner!!
Either way, if it were me I would definitely call the surgeon. It could even be as simple as anemia....low iron..... He would know best, at least to start with.
Please keep us posted.
Best wishes.
Marguerite