Hi emster, Wow I am sorry your having so many problems . I can relate though as I have anxiety and panic disorder with diagnosed heart diease and it is very difficult not to stress on the effects it causes.
It has actually been proven that anxiety/panic disorder can cause irregular heart rates. However, this doesnt mean that you would have a heart problem or what would be called arrythmias. I wouldnt just dismiss any chest pain or rapid heart rates as just a panic disorder though. These should always be checked out by a physician/cardiologist to rule out any type of heart diesease. Doctors will look at your family history, if anyone has had heart diease or heart attack close to you, your eating habits, exercise, any medications you take now or in the past...all of these things are essential in determining someone's risk factors for heart problems or future heart problems.
Also, what you may be experiancing could be what is called PVC's (premature ventricular contrations). This is a pretty common condition in most people, for some it is benign and not so noticiable and others it is stronger. Here is a link on it to the Mayo Clinic so you can read up and see what you think. http://www.mayoclinic.com/health/premature-ventricular-contractions/DS00949 Either way I really think you need to get a check up and talk to your physician regarding this.
Please do post again and let us know how your doing. And bty, we do also have a great anxiety/panic forum here. There are many members who post in there who are most supportive, Please do check it out...here is the link to that: https://www.healingwell.com/community/default.aspx?f=9