The PR interval is the time from the beginning of the P wave (atrial depolarization) to the beginning of the QRS complex (ventricular depolarization). The normal PR interval measures 0.12-0.20 seconds ...
In the last few weeks, the Skeptical Cardiologist has had a run on with patients with premature atrial contractions (PACs). I've discussed in detail premature ventricular contractions (PVCs) here and ...