Emergency or not

My husband who is 51 years old has been complaining today of pains in his arm and back area. They are pains which come and go. He's a very stressed person and always under pressure which doesn't help. My question is: What would we need to to if it became an emergency and would he get immediate help if he needed it? He also suffers from chronic heartburn all the time for many years now. I don't want to over-react but I also don't want to dismiss the fact that it could be serious and time could be a life-saver.