I had huge problems with my heart because of Lyme. My heart would skip a beat all the time (arrhythmia). That was pretty scary and I spent a lot of time in ERs... At times it felt like it would completely stop. I also had palpitations.
One thing that helps reduce arrhythmia is magnesium supplements. I take 450 mg mag glycinate every day. Other good sources of magnesium: citrate and lactate.
And I too have been suffering from panic disorder for many years... I know how you feel. With proper treatment and time, it will get better, I promise :o)
I thought I would chime in and mention that I, too, often have skipped heart beats. I have CFS though. I used to have palpitations years ago and my physicians could never figure out the cause. Now I know that those were also due to my health condition.