I'm a bit worried.

[Yuuriko]

Before I begin, let me give you a bit of background.
I'm currently 13 years old. I was rushed to the hospital a month ago due to an anxiety attack. I had 200 beats per minute, which was alarming at the time. The next morning, I was diagnosed with hypokalemia. They hooked me up to an IV (with oral potassium chloride), which eventually brought my potassium levels back to normal, and I was released.

Afterwards, I had a series of anxiety attacks. About an average of three a day for about two weeks. From then on, I began to worry about things like heart attack, stroke, and even heart arrhythmia. I know that it is extremely uncommon for a 13 year-old to have ANY cardiac issues, it's possible, although very rare.
Because of this reason, my doctor would not make a referral for a cardiologist, but a pediatrician instead.

What makes me worry about this so much is the fact that it FEELS like my heart skips beats. I've developed a habit of placing my hand on my heart, to check the way it's beating. I also have mild chest pain from time to time, along with pain in other areas of my body. Is it just anxiety that's to blame? I sure hope so.
"Muscle spasms" are also common. Sometimes it feels like my heart is "quivering".

Not being able to control my body makes me feel so helpless. I have broken down a few times because of it.

[CFS56]

Have you seen the pediatrician yet?  You need to tell him your symptoms and how concerned you are about them.  Even if he doesn't refer you to a cardiologist, maybe he could do a few tests to ease your mind.  I know first hand how scary heart issues are and it will be hard to get your anxiety under control when you are so scared. I would also suggest you talk to your parents about what is going on, maybe they can help.  And a word from somebody that has had a stupid acting heart for 40 some years...the more you worry and think about it, the worse it's going to get.  Try to do things that will distract your worry.  Hang in there.

[softlyasinamorningsunrise]

These sounds like PVC's (premature ventricular contractions), palpitations that are generally benign. They can happen in response to excess caffeine, stress, or anxiety. In other words, your anxiety may be causing the very symptom which then worsens your anxiety.

If someone has an anxious temperament, he/she may be more likely than others to develop anxiety about possible illness. Many people who develop anxiety disorders see their onset at about your age. If it's still troubling you, might want to see someone for counseling. If it's severe, you might consider medications.