[The influence of respiratory pattern on heart rate variability analysis in heart failure].

INTRODUCTION

Autonomic dysfunction is present early in the course of heart failure, and has a direct role on deterioration of cardiac function and prognosis. Heart rate variability (HRV) estimates sympathovagal control of heart frequency. The influence of respiratory pattern on HRV is clinically important. Breathing disorders are common in heart failure and highly affect HRV and autonomic evaluation. It was previously shown that slow and deep breathing increased parasympathetic tone, but effects of this respiratory pattern on HRV were not evaluated.

OBJECTIVE

The aim of the study was to estimate effects of slow and deep breathing (SDB) on HRV in heart failure patients.

METHOD

In 55 patients with heart failure (78% male, mean age 57.18 +/- 10.8 yrs, mean EF = 34.12 +/- 10.01%) and 14 healthy controls (57.1% male, mean age 53.1 +/- 8.2 yrs), short term HRV spectral analysis was performed (Cardiovit AT 60, Schiller). VLF, LF, HF and LF/HF were determined during spontaneous and deep and slow breathing at 0.1 Hz (SDB).

RESULTS

LF, HF and LF/HF significantly increased during SDB compared with spontaneous breathing both in controls (LF 50.71 +/- 61.55 vs. 551.14 +/- 698.01 ms2, p < 0.001; HF 31.42 +/- 29.98 vs. 188.78 +/- 142.74 ms2, p < 0.001 and LF/HF 1.46 +/- 0.61 vs. 4.21 +/- 3.23, p = 0.025) and heart failure patients (LF 27.37 +/- 36.04 vs. 94.50 +/- 96.13 ms2, p < 0.001; HF 12.13 +/- 19.75 vs. 41.58 +/- 64.02 ms2, p < 0.001 and LF/HF 3.77 +/- 3.79 vs. 6.38 +/- 5.98, p = 0.031). Increments of LF and HF induced by SDB were significantly lower in patients than healthy controls. Heart failure patients had lower HRV compared to healthy controls both during spontaneous breathing and SDB. During spontaneous breathing, only HF was significantly lower between healthy controls and patients (p = 0.002). During SDB VLF (p = 0.022), LF (p < 0.001) and HF (p < 0.001) were significantly lower in heart failure patients compared to controls.

CONCLUSION

These data suggest that SDB increases HRV both in healthy and heart failure patients; the highest increment is in LF range. Differences in spectral profile of HRV between healthy controls and heart failure patients become more profound during SDB. Controlled respiration during HRV analysis might increase sensitivity and reliability in detection of autonomic dysfunction in heart failure patients.