My GP was concerned with my unusual heart beat so he got an ECG organised in the surgery he didn't like the result and ordered an ambulance to take me to hospital. I was admitted and several ECG's were taken along with blood tests. The head Doctor came to see me next day and explained that the main concern from my GP was there was no output or movement on the F line he said that he wasn't concerned about this and could go home. Can you explain what is the F line is and what is its purpose and who was right my GP or the Hospital Doctor. Thank you.