Abstract：Objective To investigate the morphological characteristics of Lorenz-RR scatter plot in patients with rapid atrial arrhythmia and its formation mechanism. Methods We selected 73 patients diagnosed with rapid atrial arrhythmia by ambulatory electrocardiography (AECG) examination, including 7 cases of atrial tachycardia, 32 cases of atrial flutter, 13 cases of impure atrial flutter and 21 cases of atrial flutteratrial fibrillation. By using 12lead AECG recorder and analysis software produced by DMS company, retrospective study was carried out on Lorenz-RR scatter plots with all the heart beats. The characteristics of scatter plots in each group were summarized. We analyzed the ECG features, FF interval, atrial frequency, morphological types of F wave, the presence or absence of equivalent potential line, and their association with morphological characteristics of Lorenz-RR scatter plot. ResultsA mong the 7 cases of atrial tachycardia, 2 are presented as individual ellipses, 3 are multi-distributional ellipses, and 2 look like grid-shaped block masses. Among the 32 cases of atrial flutter, 2 are presented as multi-distributional ellipses, 26 are clear grid-shaped block masses, and 4 are vague grid-shaped block masses. In the 13 cases of impure atrial flutter, 2 look like clear grid-shaped block masses, 10 are vague grid-shaped block masses, and one is fan-shaped with vague block masses. The scatter plot of atrial flutter-atrial fibrillation is fan-shaped with vague block masses or without block mass. Conclusion The morphological characteristics of Lorenz-RR scatter plot in patients with rapid atrial arrhythmia are related to the frequency and regularity of atrial cycle, and are also associated with changes of atrioventricular node refractory period. At a slow and regular atrial frequency, the scatter plot is presented as individual or multi-distributional elliptic block mass; at a quick and regular atrial frequency, it looks like clear grid-shaped block mass. With a loss of regularity in atrial frequency, the boundary of block mass gradually becomes blurred—developing from clear grid-shaped block mass to vague one and then fan-shaped graphics with or without block mass. The number of block mass is related to the proportion of atrioventricular conduction; the enlargement or diffusion of individual block mass is influenced by the variability of atrial cycle and changes of atrioventricular node refractory period.
