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HEART RATE VARIABILITY AS A PREDICTOR OF SEVERITY IN CIRRHOSIS LIVER
A Somasundaram, K Muralikrishnan, J Varghese, P Mohan, R Ponnusamy, A Murali, K Balasubramanian, V JayanthiStanley Medical College, Chennai, India
Aims: Autonomic nervous system (ANS) dysfunction is documented in cirrhosis liver. Heart rate variability (HRV) is the oscillations in the interval between consecutive instantaneous heart beats as well as the oscillations between consecutive instantaneous heart rates. ANS function can be quantified by short term HRV analysis. Aim of the present study was to test ANS function in cirrhotics by analyzing short term HRV, to determine whether or not the degree of autonomic dysfunction is correlated with the severity of disease, and, also, to compare the changes of HRV between bleeders/non-bleeders and survivor/non-survivor groups on follow-up.
Methods: HRV was performed in cirrhotic men, age range 20-62 years, non diabetic, non-alcoholics and non-hypertensives and compared with age matched male healthy controls. Short term HRV (for 5 min) was done using RMS polyrite 2.5.2 software (India) in supine rest and upright position. Mean RR interval, SDNN (Standard Deviation of all the Normal to Normal intervals), and the Fast Fourier Transformation frequency statistics i.e. (i) Low Frequency (LF) and High frequency (HF) power (in percentage (%) and normalized units (n.u)), and (ii) LF/HF ratio were analyzed.
Results: 38 cirrhotics (Child Pugh class A: 6; B: 19; C: 13) and 22 healthy controls were included in the study. 12 patients died on follow up. The cause of death was - Hepatoma: 2; Spontaneous bacterial peritonitis: 4; Variceal Bleed: 5; and Leptospirosis with renal failure: 1.
Cirrhotics had a significantly lower (p < 0.05) SDNN (implying reduced HRV) and an increase in LF power (in n.u; p value 0.03) i.e. increase in sympathetic tone, in supine posture. In upright posture, the LF power (in percentage; indicative of autonomic function, predominantly sympathetic) and the LF/HF ratio (indicative of sympathovagal balance) was significantly low (p value 0.005) i.e. no increase in sympathetic tone in upright position. The decrease in SDNN accompanied with an increase in LF power, from supine to upright posture, observed in controls, was not seen in cirrhotics. With advancing liver disease (CTP class A vs B vs C), the LF power (in %) decreased significantly; implying reduced autonomic function; predominantly of sympathetic tone. However, there was no difference in the various parameters between bleeders/non-bleeders and survivors/non-survivors.
Conclusions: Cirrhotics had significantly reduced heart rate variability and an altered sympathovagal balance with an absent increase in sympathetic tone on standing. With advancing liver disease, there was an increasing autonomic dysfunction, predominantly of the sympathetic component. However, the HRV parameters did not differ significantly between bleeders/non-bleeders and survivors/non-survivors.