Actually, gabapentin is used for anxiety
, in higher doses than those used for nerve pain. It's off-label, of course, but isn't everything these days? I only know this because my psychiatrist is considering it for my anxiety, and that forced me to research it, otherwise I'd be clueless. How well it works is another matter. But heart rate isn't causing your anxiety here. Some people get an increased heart rate from anxiety, but most just feel like they do and actually don't.