The medical meaning of excessive PR is prolonged PR interval, which indicates a block in atrial to ventricular signaling. PR is the distance from the P wave to the QRS wave in the ECG image, and is clinically significant in terms of atrial-to-ventricular conduction velocity. The normal PR interval in adults is 0.12s to 0.2s, which is 3 to 5 frames in the electrocardiogram, so the prolongation of the PR interval in the electrocardiogram is more than 5 frames. The clinical significance is the prolongation of cardiac excitation signal conduction through the atria to the ventricles, and its etiology is mostly related to atrioventricular block, myocardial ischemia and other factors. If PR interval prolongation is found, it needs to be treated according to its cause.