The interval between complexes is regular and the pacemaker is in the sinoatrial node and whose conduction through the atria, atrioventricular node, and ventricles are unimpaired.

The problem arises in the Sinus node causing a P wave on the surface of ECG. It can be classified as a sinus rhythm with a resting heart rate of 60 beats per minute or less, some are asymptomatic until heart rate goes under 50.

A type of a fast heart rate due to improper electrical activity in the ventricles of the heart. This may be caused by an existing coronary heart disease, cardiomyopathy and electrolyte problems which may result to lightheadedness, chest pain or cardiac arrest.

Regular rhythm P Wave is Normal PR Interval is Normal (0.12-0.20 sec) QRS Wide (>0.12 sec)

Rhythm is not present Rate is absent P Wave is Absent PR Interval is Absent QRS is absent

Rhythm is regular Rate is normal (60-100 bpm) P Wave is present before, during (hidden) or after QRS, if visible it is inverted PR Interval is not measurable QRS is normal (0.06-0.10 sec)