Objective: The purpose of our study was to describe Doppler sonography patterns of venous flow in the portal system of healthy subjects and to compare pulsatility of flow with subjects' body mass, degree of inspiration, and body position.
Subjects and methods: Doppler signals from the main, right, and left portal veins; superior mesenteric vein; splenic vein; and inferior vena cava of 23 healthy adults were prospectively studied. Pulsatility of flow was quantified using an index of venous pulsatility (VPI = [maximum frequency shift-minimum frequency shift]/maximum frequency shift). Antegrade flow peak velocities were also related to ECG tracings the time between two R waves being divided into four equal parts for analysis. The caliber variations of the main portal vein and inferior vena cava were measured with M-mode sonography. Doppler tracings were obtained with subjects in supine and sitting positions and during mid and deep inspiration. The subjects' heights and weights were obtained and the body mass index calculated (weight/[height2]).
Results: In the portal vein, the VPI was 0.48 +/- 0.31 (mean +/- SD). Marked pulsatility of venous flow (VPI > 0.5) was found in 12 of 23 subjects. We found an inverse correlation between the VPI and the subjects' body mass index (r = -.76; p < .001). Portal vein pulsatility decreased significantly during sitting (p < .05) and deep inspiration (p < .01). The portal VPI was correlated with caliber variation of the inferior vena cava (r = .59; p < .05). In the portal venous system, antegrade flow peak velocities occurred most often during the third quarter of the cardiac cycle, particularly in the splenic vein.
Conclusion: Doppler sonography shows pulsatile portal venous flow in healthy adults, especially in thin subjects. This pulsatility has an inverse correlation to body mass. The finding of a pulsatile portal vein needs to be interpreted in clinical context and does not necessarily imply dysfunction of the right side of the heart.