Geometric index of heart rate variability in chronic obstructive pulmonary disease [Índices geométricos de variabilidade da frequência cardíaca na doenc ̧a pulmonar obstrutiva crónica]

Background: it was already evidenced decreased heart rate variability (hrv) in chronic obstructive pulmonary disease (copd) patients at rest. objective: in order to insert new elements in the literature regarding this issue,we evaluated geometric index of hrv in copd subjects. method: we analyzed data from 34 volunteers,divided into two groups according to spirometric values: copd (17 volunteers,fev1/fvc = 47.3±10.2; fev1 = 50.8±15.7) and control (17 volunteers,fev1/fvc = 78.8±10.8; fev1 = 100.1±14.7). for analysis of hrv indexes the volunteers remained in the supine position for 30minutes. we analyzed the following indexes: triangular index (rrtri),triangular interpolation of rr intervals (tinn) and poincaré plot (sd1,sd2 and sd1/sd2). student's t-test for unpaired samples and mann---whitney test were used for data analysis. results: we observed statistically significant reductions in geometric indexes in the copd group: rrtri (0.043±0.01 vs. 0.059±0.02; p = 0.018),tinn (105.88±51.82 vs. 151.47±49.9; p = 0.014),sd1 (9.76±4.66 vs. 14.55±6.04; p = 0.014) and sd2 (34.86±17.02 vs. 51.51±18.38; p = 0.010). sd1/sd2 (0.30±0.11 vs. 0.28±0.07; p = 0.605) were not significantly different between groups. patients with copd presented a visual analysis of poincaré plot of lower dispersion of rr intervals both beat-to-beat and the long-term. conclusion: subjects with copd present reduction of geometric indexes of hrv,indicating reduced heart rate variability. © 2011 sociedade portuguesa de pneumologia. published by elsevier españa,s.l. all rights reserved.