Portal pressure measurements

Question: A transjugular liver biopsy is performed on your cirrhotic patient and a HVPG (hepatic vein/portal gradient) is recorded as follows: right atrial pressure = 4 mmHg; free hepatic vein pressure = 12 mmHg; wedged hepatic vein pressure = 14 mmHg.  The subsequent biopsy shows cirrhosis and this patient has ascites, so you’re left scratching your head as you try to figure out why the HVPG here is only 2 mmHg (wedge pressure minus free pressure).  What is the most plausible reason for the clinical discrepancy?

A. this patient has schistosomiasis

B. this patient is probably intoxicated with cocaine

C. this patient has a stenosis in the IVC

D. the catheter was probably pushed too far into the hepatic vein during the “free” pressure measurement

Answer: This may be the most challenging question ever posted on thebileflow, and not only because there is more than one correct answer.  Let’s eliminate the cocaine answer immediately because it has no relationship to this scenario.

Schistosomiasis.  Classic teaching states that this is a pre-sinusoidal condition (although in reality, when advanced, it becomes a sinusoidal distortion).  Nevertheless, when a pre-sinusoidal condition is present, the wedge minus free pressures should be about equal, and this is the case here.  However, the right atrium pressure is only 4 and schistosomiasis alone cannot explain this discrepancy.

Stenosis in IVC.  Recall that the IVC connects the right atrium to the hepatic vein, and therefore a healthy/patent IVC means that the RA and HV pressures should be equal.  However, if there is a stenosis in the IVC, the proximal pressures (RA) will be lower than the distal pressure (HV), and may explain the case scenario above.  This anatomic anomaly could falsely elevate the free HV pressure and obscure the HVPG measurement.  This is an acceptable answer choice, but not the most likely.  The most likely explanation is…

The catheter is pushed too far into the HV during the “free” pressure measurement.  When this happens, the “free” measurement reflects the wedge pressure because it’s pushed up against the walls of the HV; by pulling back several centimeters, a truer free pressure is achieved, and it should be the same pressure as what’s seen in the right atrium.  This is the most likely answer- this patient has a HVPG of 10 mmHg, which explains the cirrhosis and ascites.  Good job!

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