This web site will guide you through the process of interpreting the heart rhythm from an electrocardiogram tracing.

  Place the ECG or rhythm strip in front of you, then follow a series of questions.  At the end a list of differential diagnosis with sample ECG tracings will be given.

First, look at the series of QRS complexes.  Is the rhythm regular or irregular, i.e. is the interval between the R waves (RR interval) constant?

Regular

Irregular