I had the same problem. Every few seconds my heart would hurt like someone hit it with a sledge hammer. I had this occur on minor occasions at night when I tried to lay down and sleep, but as I got older it would occur during the day also.
My cardiologist did an utrasound and said that I had a benign heart arythmia. He put me on toprol (I also have high blood pressure) and this seems to have fixed the problem.
Good luck!!!!!!!!!!!!!!