abnormal PR interval MP:0003901 MPheno.ontology The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. The PR interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node and entering the ventricles. The PR interval is therefore a good estimate of AV node function. anomaly in the length of time between the beginning of atrial depolarization and the beginning of ventricular depolarization, measured by the interval from the beginning of the P wave to the beginning of the QRS complex abnormal atrioventricular node conduction abnormal heart electrocardiography waveform feature