Weak pulse what could it be?

My friend has irregular heart beats 1000's a day, he's 30 years old and this has been going on for at least 8 years, well his doctor is sending him to see a cardiologist that is going to perform a complete cardiac exam. They wanna rule out a previous heart attack first. So i felt his pulse to feel the irregular beat or pause/skip btw hes having a lot of pvcs, so felt a faint pulse in the left arm, and felt a strong pulse in the right arm, he also has a hard time getting a bp reading from his left arm. His mother couldn't get a reading at all in her left arm but she's had so many tests ran and still nothing was found wrong with her except some pvcs, lack of bp in the left arm. What do you think? Hace you ever heard of this? I mean he's 30 years old decent cholesterol, bp isn't too bad, and he wasn't born with anything wrong, and has no family history of fmily members having these problems especially at such a young age.