Heart rate variability analysed by Poincaré plot in patients with metabolic syndrome

• Heart rate variability was analysed by Poincaré plot in metabolic syndrome patients.
• The tilt table test at a controlled breathing frequency 20 times/minute was used.
• SD1 and SD2 values are lower in metabolic syndrome patients.
• Lower values of SD1 and SD2 are indicative of autonomic dysfunction.

IntroductionThe SD1 and SD2 indexes (standard deviations in two orthogonal directions of the Poincaré plot) carry similar information to the spectral density power of the high and low frequency bands but have the advantage of easier calculation and lesser stationarity dependence.MethodsECG signals from metabolic syndrome (MetS) and control group patients during tilt table test under controlled breathing (20 breaths/minute) were obtained. SD1, SD2, SDRR (standard deviation of RR intervals) and RMSSD (root mean square of successive differences of RR intervals) were evaluated for 31 control group and 33 MetS subjects.ResultsStatistically significant lower values were observed in MetS patients in supine position (SD1: p = 0.03, SD2: p = 0.002, SDRR: p = 0.006, RMSSD: p = 0.01) and during tilt (SD2: p = 0.004, SDRR: p = 0.007).ConclusionSD1 and SD2 combining the advantages of time and frequency domain methods, distinguish successfully between MetS and control subjects.