Heart rate variability in the clinical assessment of patients with chronic liver disease

Figure 1 Typical electrocardiogram recording and obtention of heart rate variability measurements. Starting from a typical electrocardiogram (ECG) recorded using a Holter monitor, after digitalization and edition, the R waves (RR intervals) file or inter-beat interval is obtained, which is used to determine the variation in RR with time and for creating the heart rate variability (HRV) waveform. Three different measurements can be obtained: (1) Time domain HRV: Based on different descriptive statistics and distribution of RR data; (2) Frequency domain HRV: The original HRV trace is separated into a spectrum of frequencies as described in Table 1 (very low frequencies, low frequencies, and high frequencies); and (3) Nonlinear parameters: Based on the complexity and regularity of RR data. ECG: Electrocardiogram; HRV: Heart rate variability; IBI: Inter-beat interval.

Figure 2 Proposed utility of heart rate variability in chronic liver disease. Heart rate variability can be assessed across different stages of chronic liver disease progression with different aims at each stage.