electric blankets ??

Don't know if any of you have heard this before, but a nurse told my wife that if you have a stent in your heart ( my wife does )not to use an electric blanket or electric heat pad. We were discussing this Sunday when my mother and sister were here and the said they were told the same thin. Have not talked to the Cardiologist as of yet, but it will be a question I will ask when I go back to be sure.
This may be wrong, I don't know for sure, just wanted to warn any who may need this info. If I can get an answer, I will post it here. If any one else has a firm answer please post it.