Hepatic venous pressure gradient in 2010: Optimal measurement is key

T he first documented attempt to measure portal venous pressure was made over 110 years ago in a dog: a cannula was inserted into the mesenteric vein, and it was connected to a water manometer. Over the next 5 decades, portal pressure could be measured in human beings only by invasive procedures such as direct portal vein catheterization and splenic pulp pressure measurements. In 1951, an indirect measurement method was described in which a small catheter was advanced into the hepatic vein and wedged so that it could not be advanced any further, and this formed a continuous static column of blood between the catheter and the hepatic sinusoids. This wedged hepatic vein pressure (WHVP) equals the pressure in the hepatic sinusoids, which in turn corresponds to the portal vein pressure (in the absence of presinusoidal portal hypertension). Several studies have assessed the direct correlation of WHVP to portal vein pressure and have documented very good concordance. To eliminate variations in abdominal pressure, such as those occurring with ascites, the free hepatic vein pressure (FHVP; i.e., the unwedged pressure in the hepatic vein) is currently used as an internal zero reference. The difference between WHVP and FHVP—the hepatic venous pressure gradient (HVPG)—is a measure of the severity of portal hypertension. In 1979, the measurement of WHVP was modified by the use of a balloon occlusion catheter, which yields a more reproducible measurement as it allows a more uniform and greater area of occlusion of the sinusoidal bed. The occluded wedge hepatic venous pressure also correlates very well to portal vein pressure. In 2004, the optimal technique for measuring HVPG was well described. In 1987, one of us suggested that HVPG was underused as a prognostic test in chronic liver disease. Since then, many studies have shown its strong predictive power for mortality, which notably is independent of the severity of liver disease as measured by the Child-Pugh or Model for End-Stage Liver Disease scores but improves their predictive power when it is combined with them. HVPG also predicts the advent of complications of cirrhosis. Patients with an HVPG below 10 mm Hg have a 90% chance of not decompensating over the next 4 years. Varices develop only at an HVPG greater than 10 mm Hg and bleed at an HVPG greater than 12 mm Hg. In patients with acute variceal hemorrhage, an HVPG 20 mm Hg is associated with worse outcomes and identifies patients who would benefit from early transjugular intrahepatic portosystemic shunt (TIPS) placement or other therapies. An HVPG 10 mm Hg identifies patients with Child A cirrhosis who are likely to obtain excellent outcomes after curative resection of hepatocellular carcinoma. Our group and others have proposed HVPG measurement as an important marker in assessing prognosis and fibrosis in patients with chronic viral hepatitis. This has been shown to be useful after liver transplantation for HCV-related cirrhosis and for chronic hepatitis B–related cirrhosis after antiviral treatment. Changes in HVPG after pharmacological intervention have been used to define an optimal hemodynamic response, which is a reduction of HVPG of 20% from the baseline or to <12 mm Hg. This predicts a low risk of future bleeding in both primary and secondary prophylaxis. However, even patients who do not achieve these targets have some protection from bleeding. Importantly, lesser reductions in HVPG are also associated with a reduction in both mortality and other complications of cirrhosis, such as spontaneous bacterial peritonitis and encephalopathy, which can be independent of any concomitant improvement in liver function. The aforementioned studies demonstrate the utility of measuring HVPG. Thus, the appropriate and correct measurement of HVPG is an important issue both in clinical research and with more widespread use, as has been repeatedly advocated. In this issue of HEPATOLOGY, La Mura and colleagues provide data that are helpful in further Abbreviations: FHVP, free hepatic vein pressure; HAPG, hepato-atrial pressure gradient; HVPG, hepatic venous pressure gradient; RAP, right atrial pressure; TIPS, transjugular intrahepatic portosystemic shunt; WHVP, wedged hepatic vein pressure. Address reprint requests to: Andrew K. Burroughs, Liver Transplantation and Hepatobiliary Medicine, Royal Free Hospital, Pond Street, Hampstead, London NW3 2QG, United Kingdom. E-mail: andrewburroughs@royalfree.nhs. uk. CopyrightVC 2010 by the American Association for the Study of Liver Diseases. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hep.23710 Potential conflict of interest: Nothing to report.