Physiological Mechanism of Pulsatility of Portal Venous Flow in Healthy Adults

Portal venous (PV) flow Doppler velocimetry assesses venous congestion in heart failure, showing PV pulsatility due to backward transmission of right atrial pressure (RAP) through the sinusoids. However, PV pulsatility has also been observed under physiological conditions. We aimed to elucidate the mechanisms and contributing factors of PV pulsatility in healthy adults. Pulsed-wave Doppler recordings of the hepatic venous (HV) and PV flow were obtained with electrocardiography. A- and V-wave velocities and their timings relative to the P- and R-waves (P-HVA, R-HVV) were measured from the HV waveforms. From PV waveforms, atrial and ventricular systolic descent flow velocities and their timings (P-PVA, R-PVV) were measured. The PV pulsatility index (VPI) was calculated. There were no differences between P-PVA and P-HVA, and between R-PVV and R-HVV, indicating similar waveforms. Seventy-nine percent of participants showed a VPI ≥ 0.3, with a higher VPI in younger vs. older participants (0.7 vs. 0.3, p < 0.01). Only age was independently associated with VPI (β = −0.56, p < 0.01). PV pulsatility was common in healthy adults, suggesting RAP transmission via the sinusoids; this physiological phenomenon was attenuated with aging. These findings highlight the importance of considering age-related physiological changes when interpreting the PV flow.