[Chaotic Features on Excess/Deficiency Syndrome of Chronic Stable Angina Pectoris Based on Analyzing Approximate Entropy of Heart Rate Variability].

Objective To analyze the chaotic degree of excess/deficiency syndrome (ES/DS) in chronic stable angina pectoris (CSAP) patients by observing 24-h dynamic changes of approximate en- tropy index of heart rate variability per hour, and to observe dynamic changing features. Methods From November 2009 to June 2011, a total of 187 CSAP patients were assigned to ES (36 cases) , DS (42 ca- ses) , intermingled syndrome of deficiency and excess (109 cases, abbreviated as intermingled ES/DS) according to TCM syndrome differentiation standards.24 h dynamic electrocardiograms were collected u- sing USA DMS dynamic ECG, which was then divided into 24 continuous period by hour. The approximate entropy algorithm (by hour) was respectively calculated. The approximate entropy diurnal variation trend was analyzed in patients with different TCM syndromes. These results were controlled with 30 healthy subjects who had normal physical examinations at the same hospital. Results The approximate entropy mean value of each hour throughout the day was lower, as compared with the healthy group (F=7. 847, P <0. 01). Although no statistical difference existed among ES, DS, intermingled ES/DS (F =1. 585, P = 0. 208), the approximate entropy mean value showed the tendency of ES >intermingled ES/DS > ES. From 8:00 a.m. to 7:00 a.m. on the next day, the variation tendency of four-group curves all showed that the approximate entropy level changed as time went by (F =2. 655, P <0. 01). Besides, the approximate en- tropy diurnal variation of ES, DS, intermingled ES/DS showed a similar trend (F =1. 011 ,P =0. 457) , but different from the healthy group (F = 1. 583, P = 0. 003). The curve in the healthy group showed "two peaks and one valley" type [one peak from 10:00 to 14:00, and the other peak from 22:00 to 02:00]. The curve for ES, DS, intermingled ES/DS showed an inverted dipper type [only a peak at night, and a relatively stable curve from 8:00 to 19:00]. Compared with the normal group, the day peak disappeared in CSAP patients, and the daytime approximate entropy was significantly reduced (F = 10. 315, P <0. 01). Conclusions Compared with the healthy group, the approximate entropy of CSAP patients decreased, which means the chaotic degree reduced. The adaptability of the cardiovascular system to external envi- ronment changes was weakened, which was more obviously seen at daytime than at night. The chaotic degree showed gradually decreasing trend (ES > DS >intermingled DS/ES).