A 20 year old female university student came to the clinic complaining of palpitations. She has had occasional rapid heart rates but never lasting more than 2 minutes. This time it has lasted for over 15minutes. The patient has been sleeping 4 hours or less a night while studying for anatomy exams. She has also been binge drinking coffee attempting to stay up. Her father died of a heart attack when he was 50. BP 95/80 P: 180 beats/min Patient is anxious, pulse extremely rapid and regular. No murmurs are present and the lungs ar clear. Massage of the carotid bifurcation slows the heart rate down. Q: What is the normal electrical flow of depolarization through the heart? How has this changed here?