Abstract:Taking time as the horizontal coordinate and PR interval of each heart beat as the vertical coordinate, we can obtain time-PRinterval scatterplot, that is, tPR scatterplot. Arrhythmias involving PR interval changes such as intermittent ventricular preexcitation, PR interval prolongation, atrioventricular block, operation of special function of pacemaker, etc. are manifested by characteristic morphological changes on t-PR scatterplot, which lays foundation for the diagnosis. The t-PR scatterplot provides an important supplement to the macro-information of t-RR scatter plot.