Thank you for your question.
According to the details provided by you, your mother is suffering from
heart failure with copd. And now she has an associated
hoarseness of voice. Does she have
cough at present? Or difficulty in swallowing? It would be prudent to visit an
ENT specialist in order to check her throat and rule out any problems there. The use of an Endotracheal tube to help her to breathe during anaesthesia in surgery can also cause hoarseness of voice which can last upto 3 or 4 weeks. This too can be confirmed by an ENT specialist. A chest Xray may also help to rule out any other causes.
In certain situations, the
nerve to her voice organ or the
larynx may be pressed upon by something leading to hoarsness. Again an Xray may help wit this. One other situation you should bear in mind is that since she has heart failure, her heart is probable dilated or swollen. Sometimes ( though rarely) an
enlarged heart may press upon her voice organ nerve leading to hoarseness of voice (this is called Ortner's syndrome).
If I were your mothers physician I would get an ENT opinion as well as a chest Xray. Further investigations maybe needed according to the discretion of your physician.
I hope this will help you to take a decision regarding further management for your mother. If you need further clarifications please do get back to me.