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Ultrasound technique to measure portal hypertension/liver stiffness

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Anyone who has had a chance to examine their old liver after

transplant knows how stiff and hard it is compared to cow liver in

the butcher shop. This stiffness has been found to correlate with

portal hypertension.

Portal hypertension is elevated pressure in certian blood vessels

leading to the liver and the cause of leathal bleeding in liver

failure. It looks like there is finally a good non-invasive way to

measure the pressure. This could lead to better evaluation of

treatments of portal hypertension. Perhaps Losartan is better than

inderol at treating portal hypertensionbut it is hard to compare the

two with invasive testing but should be easy to compare with

ultrasound.

Liver Stiffness Measurement May Predict Severe Portal Hypertension

CME

News Author: Laurie Barclay, MD

CME Author: Désirée Lie, MD, MSEd

Disclosures

Release Date: May 7, 2007; Valid for credit through May 7, 2008

Credits Available

Physicians - maximum of 0.25 AMA PRA Category 1 Credit(s)™ for

physicians;

Family Physicians - up to 0.25 AAFP Prescribed credit(s) for

physicians

May 7, 2007 — Transient elastography may predict severe portal

hypertension in patients with hepatitis C virus (HCV)–related

cirrhosis, according to the results of a study reported in the May

issue of Hepatology.

" Measurement of hepatic venous pressure gradient (HVPG) is a standard

method for the assessment of portal pressure and correlates with the

occurrence of its complications, " write Francesco Vizzutti, from the

Università degli Studi di Firenze/Azienda Ospedaliero Universitaria

Careggi in Firenze, Italy, and colleagues. " Liver stiffness

measurement (LSM) has been proposed as a noninvasive technique for

the prediction of the complications of cirrhosis. "

The investigators evaluated the ability of liver stiffness

measurement to predict severe portal hypertension compared with that

of HVPG in 61 consecutive patients with chronic HCV-related liver

disease.

In the overall population, there was a strong relationship between

liver stiffness measurement and HVPG measurements (r = 0.81; P

< .0001). The correlation was excellent for HVPG values less than 10

or 12 mm Hg (r = 0.81; P = .0003 and r = 0.91; P < .0001,

respectively). However, linear regression analysis was not optimal

for HVPG values of 10 mm Hg or greater (r2 = 0.35; P < .0001) or 12

mm Hg or greater (r2 = 0.17; P = .02).

The areas under the receiver operating characteristic curves were

0.99 for the prediction of HVPG of 10 mm Hg or greater and 0.92 for

the prediction of 12 mm Hg or greater. At liver stiffness measurement

cutoff values of 13.6 and 17.6 kPa, sensitivity was 97% and 94%,

respectively.

In patients with cirrhosis, liver stiffness measurement positively

correlated with the presence of esophageal varices (P = .002).

However, there was no apparent correlation between liver stiffness

measurement and size of esophageal varices. Area under the receiver

operating characteristic curve for the prediction of esophageal

varices was 0.76, and at a liver stiffness measurement cutoff value

of 17.6, kPa sensitivity was 90%.

" LSM represents a non-invasive tool for the identification of chronic

liver disease patients with clinically significant or severe portal

hypertension and could be employed for screening patients to be

subjected to standard investigations including upper GI endoscopy and

hemodynamic studies, " the authors conclude. " Measurement of liver

stiffness by transient elastography may represent a reliable non-

invasive methodology for the prediction of clinically significant and

severe portal hypertension, although not good enough to replace

endoscopy for the detection of varices. "

The Italian MIUR, the University of Florence, and the Italian Liver

Foundation supported this study. The authors have disclosed no

relevant financial relationships.

Hepatology. 2007;45:1290-1297.

Clinical Context

According to the authors of the current study, progression of liver

disease to cirrhosis occurs in successive stages of liver fibrosis

and noninvasive tests are needed to assess progression of liver

fibrosis and portal hypertension to optimize management. HVPG has

been used as a gold standard for the evaluation of portal

hypertension to assess the benefit of antiviral therapy, but it is

invasive and costly and available only at major centers, whereas

transient elastography is an emerging noninvasive method that has

potential for predicting hepatic fibrosis in patients with chronic

HCV-related hepatitis. Transient elastography relies on a novel

ultrasound-based technology in which the tip of an ultrasound

transducer probe is placed between 2 intercostal spaces at the level

of the right liver lobe and transmits a low frequency to the liver,

inducing an elastic shear wave that propagates through liver tissue

and is then measured to reflect liver stiffness.

This is a study of patients with chronic HCV-related hepatitis

conducted using HVPG as a gold standard to examine the predictive

value of transient elastography for portal hypertension and varices.

Study Highlights

Included were 61 consecutive patients (39 men) with

histopathologically determined chronic HCV infection who underwent

HVPG measurement.

Patients had a hemodynamic study to obtain baseline assessment of

portal pressure before starting & #946;-blockers.

16 patients had cirrhosis, and 14 patients had advanced hepatic

fibrosis.

Excluded were patients with body mass index of 35 kg/m2 or higher,

ascites, overt complications such as renal or cardiovascular

problems, hepatocellular carcinoma, or coinfection with other viruses

or those receiving antiviral therapy.

After overnight fasting, patients underwent complete upper abdomen

ultrasound followed by transient elastography using the Fibroscan

(Echosens, Paris, France) apparatus with a 5-MHz transducer probe.

An elastic shear was produced by low-amplitude vibrations, and liver

stiffness measurement was determined in a cylinder of hepatic tissue

1 cm by 2 to 4 cm.

The clinician operator had prior experience with at least 100 liver

stiffness measurement procedures.

After liver stiffness measurement was determined, HVPG (portal

pressure gradient) and transjugular liver biopsy were performed using

local anesthesia.

The operator was unaware of patient's liver disease status.

Clinically significant portal hypertension was defined as an HVPG of

10 mm Hg or greater.

Mean age was 56 years, 64% were men, mean body mass index was 23

kg/m2, 34% had no esophageal varices, and 38% had large varices.

Among 47 patients with cirrhosis, 60% were classified as Child-Pugh

class A, 30% as class B, and 10% as class C.

9% had no portal hypertension, 13% had preclinical portal

hypertension, and 77% had clinically significant portal hypertension

of whom 57% had severe portal hypertension.

Esophageal varices were present in 30 of 47 patients with cirrhosis,

gastroesophageal varices in 4, and isolated gastric varices in 1.

Patients with cirrhosis showed significantly higher HVPG and liver

stiffness vs those with advanced fibrosis (P < .0001 for both).

There was a significant correlation between HVPG and liver stiffness

measurement (r = 0.81; P < .0001).

Liver stiffness was significantly higher in patients with an HVPG of

10 mm Hg or greater and 12 mm Hg or greater than in those with that

of less than 10 mm Hg and less than 12 mm Hg (P < .0001).

Based on receiver operating characteristic curves, different cutoff

values for liver stiffness measurement were determined.

A liver stiffness measurement of 13.6 kPa or greater had a negative

predictive value of 92% and a sensitivity of 97% for the prediction

of patients with HVPG of 10 mm Hg or greater.

A liver stiffness measurement of 17.6 kPa or greater had a negative

predictive value of 91% and a sensitivity of 94% for the prediction

of patients with HVPG of 12 mm Hg or greater.

However, using a cutoff value of 17.6 kPa or greater for liver

stiffness measurement, the negative predictive value and positive

predictive value for the prediction of varices were only 66% and 77%,

respectively.

There was no correlation between liver stiffness measurement and the

size of esophageal varices.

The authors concluded that measurement of liver stiffness by

transient elastography represents a reliable and noninvasive method

for the prediction of clinically severe portal hypertension but is

not good enough to replace endoscopy for the detection of varices.

The authors suggest larger studies to collaborate these findings.

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