Heart beat abnormalities
There are several conditions that change the rate or rhythm of the heartbeat. These can cause a feeling of fluttering, trouble breathing, exercise intolerance, lightheadedness or dizziness, fainting or a feeling of faintness, exercise intolerance, chest pain or anxiety.
These are some examples of heart beat abnormalities:
Wolf Parkinson White syndrome
Multi focal atrial tachycardia (MAT)
Bundle branch block (right and left)