RESUMO
Objective@#To explore the value of vector angle of Lorenz plots(LPs) and the role of combining B-line slope in improving the diagnostic efficiency of arrhythmia．@*Methods@#LPs of 119 cases with ventricular premature contraction (VPC group ) ，97 cases with supraventricular premature contraction(SPC group) ，52 cases with type II°I atrioventricular block ( Ⅱ ° Ⅰ group) and 54 cases with type Ⅱ ° Ⅱ atrioventricular / sinoatrial block ( Ⅱ ° Ⅱ group) were retrospectively analyzed．The B-line slope and vector angle were measured，and the differences between groups were compared. Receiver operating characteristic curve was used to analyze the diagnostic efficacy of B-line slope，vector angle and their combination between groups ，and MedCalc software was used for statistical comparison．The consistency of intra-observer and inter-observer measurements of B-line slope and vector angle was evaluated using Intra group correlation coefficient (ICC) and Bland-Altman plot. @*Results@#There were significant differences between VPC group and SPC group，and between Ⅱ ° Ⅰ group and II°II group (P＜0. 05) ．The area under the curve (AUC) of B-line slope，vector angle，and the combination of the two in distinguishing ventricular and supraventricular premature contraction were 0. 81，0. 84 and 0. 87 respectively，and the AUC in distinguishing type Ⅱ ° Ⅰ and type Ⅱ ° Ⅱ atrioventricular / sinoatrial block were 0. 76，0. 78 and 0. 80 respectively．The ICC of vector angle was better than B-line slope (Intra-observer 0. 99 vs 0. 98，Inter-observer 0. 97 vs 0. 96) ．@*Conclusion@#Vector angle can be used to identify the type of arrhythmia，and has good intraobserver and interobserver consistency．Its combination with B-line slope has the highest accuracy in diagnosing arrhythmia，providing a new reference for clinical diagnosis and treatment.
RESUMO
Objective: To explore the advantage of RR-Lorenz plot (RR-LP) in analyzing the patients of sinus rhythm with long RR interval. Methods: A total of 308 RR-LP patients with long RR interval were retrospectively studied. The patients were divided into 7 groups according to the type of long RR intervals. ① Sinus bradycardia with arrhythmia group, n=63,②Repeated transient sinus arrest group, n=16, ③Ⅱ° sino-atrial block group, n=14, ④Ⅱ° atrial ventricular block (Ⅱ° AVB) group, n=47, ⑤ Un-passed atrial premature beats (APB) group, n=28, ⑥ Atrial premature beats group, n=72 and ⑦ Premature ventricular beats group, n=68. We analyzed the patients of RR interval greater than 1500 ms with ambulatory electrocardiogram record. Results: ①RR-LP of sinus bradycardia with arrhythmia group showed a single distributing area with 1500 ms for the origin of transverse and longitudinal axis with B line slope at 1, tilt angle of 45°.②RR-LP of repeated transient sinus arrest,Ⅱ° sino-atrial block,Ⅱ° AVB and APB groups showed special four distributing areas with B line slope at (0.51 ± 0.01), tilt angle of (23.04 ± 0.50) °, B line slope at 0.6, tilt angle of (27°), B line slope at (0.57 ± 0.21), tilt angle of (25.69 ± 9.59)° and B line slope at (0.50 ± 0.01), tilt angle of (22.59 ± 0.54) ° respectively.③RR-LP of premature beats groups showed special four regional distributing areas, B line slope for atrial premature beats was at (0.38 ± 0.12), tilt angle of (17.06 ± 5.22) ° and B line slope for ventricular premature beats was at (0.07 ± 0.05), tilt angle of (3.02 ± 2.39) °. Conclusion: RR-LP in patients of sinus rhythm with long RR interval had speciifc morphology and distribution features, the local abnormality could be found in a plane via all RR intervals which provided a differential diagnosis for repeated occurrence of short RR interval.