Abstract:In clinical practice, we construct RR interval scatterplot of patients with typical sick sinus syndrome(SSS) with Lorenz scatterplot mapping system included in AECG analysis software. However, in this way, the graphic changes of long interval(>2 s) can not be shown in the scatterplot. The upper limit of coordinates in Lorenz scatterplot mapping system is reseted from original 2 s to 4 s. This paper compares the similarities and differences of RR interval scatterplots in the two upper limits of coordinates, and makes confirmation with reversal analysis technique. Our study revealed that attractors were more than before by 1 to 4 in the improved RR interval scatterplot which can show complete scatterplot graphs. However, the scatterplot in a coordinate upper limit of 2 s can only display local features. Therefore, it is not appropriate to make auxiliary diagnosis of SSS with the RR interval scatterplot in a coordinate upper limit of 2 s. Its improved version taking 4 s as the upper limit of coordinates can reflect the characteristics of SSS scatterplot more completely and more effectively.