Shift in Sympathovagal Balance Toward Parasympathetic Predominance Is Associated With Attenuation of Portal Hyperperfusion in Cirrhotic Recipients Undergoing Living Donor Liver Transplant

Background. The autonomic innervation to a liver graft remains lost up to 1 year after liver transplant. Therefore, we investigated the effects of recipients' autonomic nervous activity on the extent of portal hyperperfusion of a partial liver graft in the absence of the autonomic innervation. Methods. A total of 31 cirrhotic recipients undergoing right lobe living donor liver transplant were analyzed. Following a 10-minute absence of surgical stimulation after hepatic artery and bile duct reconstruction, the electrocardiogram and blood pressure waveforms were recorded for 5 minutes. Low-frequency (LF) and high-frequency (HF) powers and their ratio (LF/HF) were calculated using fast Fourier transform from the electrocardiogram waveform. A decrease in LF/HF represents a shift in sympathovagal balance toward parasympathetic predominance. Then, portal venous (PVF) and hepatic arterial (HAF) blood flows were measured in mL/min per 100 g of liver weight using spectral Doppler ultrasonography. A decrease in their ratio (PVF/HAF) represents attenuation of portal hyperperfusion. Results. The medians of the PVF and HAF were 349 and 27 mL/min/100 g liver weight with interquartile ranges of 272 to 617 mL/min/100 g liver weight and 22 to 41 mL/min/100 g liver weight, respectively, yielding a median of the PVF/HAF of 13.7 (interquartile range, 8.5-21.3). The median of LF/HF was 0.67 (interquartile range, 0.16-1.45). With a reduction in LF/HF, PVF/HAF decreased according to an S-curve regression model between them (PVF/HAF = e(2.743)+-0.031/Lf/Hf, adjusted R-2 = 0.129, P = 0.027). Conclusion. A shift in sympathovagal balance toward parasympathetic predominance is associated with attenuation of portal hyperperfusion in a partial liver graft.