On a normal routine I would not feel my heart racing but a sudden episode of missed beat, increased awareness of heartbeat, fluttering or a sudden urge of deep breath that last for few minutes. I passed my stress test by okay margin and my Echo revealed the heart murmur.
However, in December 2005 I was caught with high rate of heart beat during a normal routine checkup. I was referred to the hospital and was on heart monitor for 6 hours, the conclusion was increased heart rate due to stress and flu.