Purpose: Direct blood flow measurement in the portal vein (PV) and in transjugular intrahepatic portosystemic shunts (TIPS) holds potential as a means of optimizing shunt creation and predicting outcomes. A retrograde thermodilutional flow measurement catheter was recently designed. The purpose of this study was to validate and optimize the technique of blood flow measurement in the PV with use of this catheter in a swine model of TIPS.
Materials and methods: Six domestic swine underwent TIPS creation. At day 14, shunts were catheterized for venography and portal blood flow measurement with use of thermodilutional catheters. Simultaneous flow measurements were made with use of the thermodilutional and perivascular methods at the same anatomic location within the PV. To test reproducibility of the flow measurement, repeated measurements were performed in the PV and shunt.
Results: Fifty-five measurements of PV blood flow with the thermodilutional catheter and perivascular probe were made in five animals. Perivascular probe placement was unsuccessful in one animal. There was high correlation between the thermodilutional and perivascular measurements (r(2) = 0.96; Q(periv) = 0.80 . Q(therm) + 147 mL/min; n = 55; range, 205-1541 mL/min). The difference between two consecutive thermodilutional measurements and their mean was less than 50 mL/min in 72% of measurements and less than 100 mL/min in 94% of measurements (N = 85 pairs).
Conclusions: Measurement of PV blood flow with use of a retrograde thermodilutional catheter system yields reliable and reproducible results. This catheter system holds promising utility as a device for measuring flow within TIPS and the PV.