Abstract：Objective To explore the application of ECG scatterplot in analyzing competitive arrhythmias, know its electrophysiological characteristics and lay foundation for rapidly analyzing ambulatory electrocardiography(AECG). Methods Typical AECG cases with common competitive arrhythmias including pararrhythmia, autonomous cardiac rhythm, escaped rhythm and multifocal atrial tachycardia were selected. The morphological features of their ECG scatterplots were analyzed while the electrophysiological characteristics were explored by using the reversal technique and based on AECG segments.Results An obvious feature of the Lorenz scatterplot of pararrhythmia was a Yshaped scatter set which sloped downwards to the right and was upside down. It indicated that the automatic rhythmicity of pararrhythmia did not rise or was slightly higher, not exceeding the variation range of sinus rhythm. By protective entrance block(without “perceptive” function for dominant rhythm), pararrhythmia can compete with sinus rhythm. The Lorenz scatterplot of autonomous cardiac rhythm was characterized by the fact that ventricular cycle(VV) and coupling interval(NV) was overlapping in sinus rhythm cycle(NN). It indicated that the automatic rhythmicity of lower pacemaker was slightly higher, reaching or slightly exceeding the frequency range of sinus rhythm. Autonomous cardiac rhythm competed with sinus rhythm by “strength”(increased automatic rhythmicity). Alternate autonomous cardiac rhythm and sinus rhythm repeated, which suggested there was no protective entrance block(with “perceptive” function for dominant rhythm). The Lorenz scatterplot feature of escaped rhythm was the squareshaped top outer boundary(capture rhythm of escape) at the distal end of constant velocity line(outside the 1.0 s line). It indicated that the automatic rhythmicity of escaped rhythm did not rise. Its rhythm readjusted at any time, suggesting there was no protective entrance block. Because of reduced dominant ventricular rate resulting from sinus node or atrioventricular nodal dysfunction, escaped rhythm can compete with dominant rhythm at a low level. The Lorenz scatterplot of multifocal atrial tachycardia was similar to the pie chart of atrial fibrillation. The automatic rhythmicity of several lower pacemakers significantly increased, almost replacing sinus rhythm; a small quantity of sinus beats can only possibly be found at the moment of block conduction from pacemakers at all levels; there was no changeless rhythm. It implied that each lower pacemaker was wellmatched in strength.Conclusion Common competitive arrhythmias are significantly characterized by ECG scatterplot which serves as a secret weapon for rapidly analyzing these kinds of AECGs. The electrophysiological meanings(including automatic rhythmicity, protective entrance block and intermittent efferent block) reflected by ECG scatterplot vary from each other, which provide important references for identification and nomenclature.
2017, Vol. 26 
