Hi,
If it is blood suppy issue, then she need to do farther investigation like magnetic resonance angiography (MRA) of her left hand,to fond out where the blood suppy is being blocked..if positive then you may go to vascular surgeons opinion..if it is non sugical case then simple free hand , isometrics , K-Cat, resisted training with theraband or wgt calf will surely improve her condition ..thank you.
Next Steps
if nothing positive comes out in MRA then pls also go for neurological investigation.