Expert: David Richardson - 7/10/2009

Question
Dear Dr. Richardson,

I have recently begun to experience pvcs (50-100 daily last two weeks. I've been told they are not harmful, but I am trying to understand the physiological reason as to why they are not harmful. I just had a few questions that I was hoping you could answer.
1. In the context of a normal heart, what prevents pvcs from leading to more dangerous arrhythmia such as vtach?
2. I've read that an "R on T" pvc can be more serious; are these usually the result of some sort of heart disease or do they occur "by chance"?

Thank you.

Answer
Dear Andy,

1.  I'm not sure.  PVCs are normal heart activity, to threat to life or health in someone with normal heart structure and function, no matter how frequent.  

2. In normal hearts, R on T doesn't occur, only in abnormal hearts, and PVC's don't lead to more dangerous arrhythmias.

Please write back if this note doesn't answer all your questions.

David Richardson