Go easy with them. I know they have a limit of 3 per day.

But I don't trust that. I never go beyond one patch a day.
And even sometimes I just use 1/2.

I've experimented with them for years. Certain placements work and others do not.

Start with the tops of the feet --the instep. With your cardiac issues, perhaps do one foot only for the first experiments.

And consider the knee. I was surprised to find behind the knee worked so well for my feet at times. I know of a study of Lidoderm against Celebrex for knee pain, so that is why I did it there for my painful right knee. The relief goes all the way down to my foot! So now I wonder how much of my "arthritic" foot pain is really referred knee compression?

There always can be an unexpected result when PN is concerned IMO.