Objectives To discuss and parse the formation principle and the graphic feature of RR-Lorenz plot of supraventricular premature beats (SPB), ventricular premature beats (VPB) and atrial fibrillation (Af) RR-Lorenz plot, and evaluate the diagnostic value of RR-Lorenz plot for arrhythmias in Holter.
Methods To screen for the Holter data which were diagnosed simple SPB and simple VPB and sustained Af, and the total number of ectopic heart beats must be more than 100 times. The Holter system input all continuous RR intervals information from the cases into the Lorenz plot software to draw a Lorenz plot automatically. To observe the graphic feature and laws of RR-Lorenz plots of SPB, VPB and Af.
Results A total of 529 cases Holter recordings were collected. According to Holter diagnosis, three groups were divided, including 174 cases SPB, 173 cases VPB and 182 cases Af. The RR-LP of SPB is a three-distribution graph, the B linear slope is 0.528 ± 0.096; While RR-LP of VPB is a four-distribution graph, the B linear slope is 0.088 ± 0.098. The RR-LR of Af was one distribution graph which is fan pattern, the fan-shaped edge close to X axis has been proved to be dynamic functional refractory period of the atrioventricular node (AVNFRP), the slope of sector bottom margin (equivalently B line) is about 0.261 ± 0.185. For B linear slope, SPB is greater than Af and greater than VPB. There is a significant difference in B linear slopes of RR-LP among three groups (P ≤ 0.05).
Conclusions In this data, there are all obviously different in the graph shape and sub-graph number and B linear slope of RR-Lorenz plots among SPB, VPB and Af. The compensatory intervals of SPB are most incomplete, which is the mechanism of forming three-distribution graph; and most VPB have complete compensatory intervals, which is the mechanism of forming four-distribution graph; RR intervals of Af are uneven, which form a evacuated scatter gram, but the seemingly random distribution of scatter points is limited within a sector, and the limited factor is AVNFRP. There is a significant difference in B linear slopes of three groups’ RR-LP, which manifest that the coupling intervals of different arrhythmias have different heart rate dependency on their previous sinus cardiac cycles. As dependent coefficient of heart beats, B linear slope shows the degree of dependence on heart rate, greater the positive heart rate dependency, the B linear slope is bigger, conversely the dependency is smaller. In this data, for heart rate dependency level, SPB is maximum, next is Af, and VPB have almost no heart rate dependency, which manifests that heart rate dependency are different in different origin groups of cardiac rhythm. This phenomenon may be connected with the type of autonomic nerve fibres and its function of control heart in this part.
RR-Lorenz plot is a method which is specially used for analysing large sample mass electrocardiogram data, so only sufficient scatter points to participate in drawing RR-LP can perfectly and steadily present graph features. Generally, the number of ectopic heart beats must be more than 100 times per 24 hours.