Poincare plot of heart rate variability: an approach towards explaining the cardiovascular autonomic function in obesity.

Obesity has been shown to affect cardiovascular function. Heart rate variability (HRV) has been an accepted method of measuring cardiovascular autonomic function. The aim of the study is to evaluate the impact of obesity on HRV using Poincaré plot (POP) analysis. A finding of sympathovagal imbalance in pre-obese adults in respiratory sinus arrhythmia (RSA) could provide important diagnostic information about early subclinical autonomic dysfunction in obesity. Thirty one obese (BMI 26.84 +/- 2.47) adult males (25.42 +/- 7.86 years) were compared with 31 normal subjects (25.38 +/- 4.61 years). In all participants, anthropometric and blood pressure (BP) measurements were performed. After rest at supine position for 5 minutes, they were asked to do control deep breathing for 1 minute. HRV was measured in terms of POP analysis. Differences in Resting heart rate (RHR) (P < or = 0.025), Pulse pressure (PP) (P < or = 0.048), SD1 (P < or = 0.042) and SD2 (P < or = 0.039) of the POP between the two groups were significant. Correlation between Body mass index (BMI) and (PP) (p = 0.19); SD1 (p = 0.47) and SD2 (p = 0.39) of the POP were significant in obese groups. Obesity is related to sympathovagal imbalance characterized by depressed parasympathetic tone and increased sympathetic activity. Nonlinear methods like POP permit simple assessment of autonomic function, despite measuring different aspects of HRV.