Heart rate variability in multibacillar leprosy: Linear and nonlinear analysis

Abstract

Objective: To evaluate the heart rate variability (HRV) in patients with multibacillary leprosy using dynamic linear and nonlinear analysis.

Material and methods: Twenty-one leprosy patients (mean age: 39.14 ±10.58 years) and 21 healthy subjects (mean age: 36.24 ± 12.64 years) completed the sample. Heart rate variability recording was performed by a Polar RS800 CX heart monitor during a period of 15 min in the supine position and 15 min in a sitting position. Analysis of HRV was performed by frequency domain from high frequency (HF) and low frequency (LF) spectral indexes in absolute and normalized units. The nonlinear analysis of HRV was calculated using symbolic analysis (0V%, 1V%, 2LV% and 2UV% indexes), Shannon entropy (SE) and normalized complexity index (NCI).

Results: Linear analysis: both groups showed higher HF values (p < 0.05) and smaller LF values (p < 0.05) in supine than in sitting position. The leprosy patients showed higher LF values (p < 0.05) and smaller HF values (p < 0.05) compared to the controls on supine position. Symbolic analysis: leprosy patients had higher 0V% values (p < 0.05), smaller 2LV% values (p < 0.05) and 2UV % values compared to healthy subjects on both positions. The 1V % had higher values (p < 0.05) for leprosy patients than for controls in the sitting position. The control subjects had smaller 0V % values (p < 0.05), and higher 2UV % values (p < 0.05) in the supine position compared to the sitting position. Leprosy patients had higher 2UV index values (p < 0.05) in the supine position compared to the sitting position. In the complexity analysis, leprosy patients had smaller SE and NCI values (p < 0.05) than the control in the supine position. There was no difference between the SE and NCI values of leprosy and the control subjects in the sitting position. The control subjects had higher SE and NCI values (p < 0.05) in the supine position than in the sitting position.

Conclusion: Leprosy patients had higher sympathetic modulation and smaller vagal modulation than controls, indicating less HRV and cardiac modulation with lower complexity. The control group displayed significant HRV differences in response to position changes while leprosy patients had fewer HRV differences after the same postural change. An analysis of HRV with linear and non-linear dynamics proved to be a reliable method and promising for the investigation of autonomic dysfunction in patients with multibacillary leprosy.

Fig 1. Linear analysis of the HRV from control group and leprosy groups for (A) low frequencies and (B) high frequencies in normalized units (nu).

Leprosy patients had higher LFnu values (lower HFnu values) than controls in the supine position. Both groups were influenced by the change from supine to sitting position. LFnu values increased and HFnu values decreased in the sitting position compared to supine position for both groups. * p<0.05 intragroup; † p<0.05 intergroup.

Fig 2. Non-linear analysis of the HRV for (A) 0V%, (B) 1V%, (C) 2LV%, (D) 2UV%, (E) Shannon entropy, and (F) NCI.

All the indexes showed differences between control and leprosy groups. The leprosy group in most of the indexes showed no differences between the sitting and supine positions. * p<0.05 intragroup; † p<0.05 intergroup.