The interpretation of hepatic venous pressure gradient tracings - excellent interobserver agreement unrelated to experience

Predictive power of portal pressure gradient remeasured shortly after transjugular intrahepatic portosystemic shunt

BACKGROUND AND AIMS

The portal pressure gradient (PPG) measured at the time of transjugular intrahepatic portosystemic shunt (TIPS) completion (immediate PPG) is easily disturbed by many factors. This study aimed to assess the diagnostic value of PPG remeasured 2-4 days after TIPS (delayed PPG) by comparison with immediate PPG.

METHODS

We retrospectively analyzed cirrhotic patients aged 18-75 years who received TIPS for preventing variceal rebleeding and pressure measurements at different time points.

RESULTS

Of 154 eligible patients, 60 (39.0%), 62 (40.3%), and 32 (20.8%) were categorized into group LL (both immediate and delayed PPG < 12 mmHg), LH (immediate PPG < but delayed PPG ≥ 12 mmHg) and HH (both immediate and delayed PPG ≥ 12 mmHg), respectively. Mean immediate and delayed PPG were 9.2 mmHg and 12.8 mmHg (p < 0.001). During a median follow-up of 22 months, the 1-year probability of variceal rebleeding was significantly lower in group LL (1.7%) compared to LH (9.8%, absolute risk difference [ARD]: - 8.2%, p = 0.028) and HH (12.6%, ARD: - 11.1%, p = 0.014), but was not significantly different between groups LH and HH (ARD: - 2.9%, p = 0.671). Delayed PPG (p < 0.001) was identified as an independent predictor of variceal rebleeding in multivariable Cox regression analysis. The area under curves of delayed and immediate PPG in predicting variceal rebleeding were 0.837 and 0.693 for all patients (p = 0.031), and 0.936 and 0.694 for patients without shunt dysfunction (p < 0.001).

CONCLUSIONS

In cirrhotic patients with variceal bleeding, delayed PPG has higher predictive power for variceal rebleeding than immediate PPG.

Endovascular Assessment of Liver Hemodynamics in Patients with Cirrhosis Complicated by Portal Hypertension

The hepatic venous pressure gradient (HVPG) is currently considered the gold standard to assess portal hypertension (PH) in patients with cirrhosis. A meticulous technique is important to achieve accurate and reproducible results, and values obtained during measurement are applied in risk stratification of patients with PH, allocating treatment options, monitoring follow-up, and deciding management options in surgical patients. The use of portosystemic pressure gradients in patients undergoing placement of transjugular intrahepatic portosystemic shunts has been studied extensively and has great influence on decisions on shunt diameter. The purpose of this study was to describe the recommended technique to measure HVPG and portosystemic pressure gradient and to review the existing literature describing the importance of these hemodynamic measurements in clinical practice.

Non-selective beta-blockers in patients with ascites: The complex interplay among the liver, kidney and heart

Non-selective beta-blockers (NSBBs) are the cornerstone of the primary and secondary prophylaxis of variceal bleeding in cirrhotic patients. They additionally prevent ascites development and death in compensated patients with clinically significant portal hypertension. After ascites onset, NSBBs remain beneficial for preventing further decompensations. However, as the cirrhosis progresses, the inflammation increases, systemic vasodilatation worsens, ascites turns refractory and cardiodynamic equilibrium becomes extremely fragile. In this scenario, NSBBs can critically impair the cardiac reserve and facilitate a haemodynamic breakdown, imperilling renal perfusion. Consequently, NSBB treatment should be carefully monitored or even avoided in such patients, and other options for portal hypertension management should be considered. In the present review, we explore the effects of NSBBs in patients with ascites and discuss the complex interplay among their hepatic, systemic and renal haemodynamic effects in this scenario.

Transjugular Portosystemic Stent Shunt: Impact of Right Atrial Pressure on Portal Venous Hemodynamics Within the First Week

Purpose

Porto-systemic pressure gradient is used to prognosticate rebleeding and resolution of ascites after TIPS. This study investigates the reliability of portal pressure characteristics as quantified immediately after TIPS placement and at short-term control.

Patients and Methods

Portal venous pressure (PVP) and right atrial pressure (RAP) were prospectively obtained before and after TIPS as well as ≥ 48 h after TIPS procedure. Porto-systemic pressure gradients (PSG) and pressure changes were calculated. A multivariate regression analysis was performed to predict portal hemodynamics at short-term control.

Results

The study included 124 consecutive patients. Indications for TIPS were refractory ascites, variceal bleeding or combinations of both. Pre- and post-interventional PSG yielded 16.4 ± 5.3 mmHg and 5.9 ± 2.7 mmHg, respectively. At that time, 105/124 patients (84.7%) met the target (PSG ≤ 8 mmHg). After 4 days (median), PSG was 8.5 ± 3.5 mmHg and only 66 patients (53%) met that target. In patients exceeding the target PSG at follow-up, PVP was significantly higher and RAP was lower resulting in the increased PSG. The highly variable changes of RAP were the main contributor to different pressure gradients. In the multivariate regression analysis, PVP and RAP immediately after TIPS were predictors for PSG at short-term control with moderately predictive capacity (AUC = 0.75).

Conclusion

Besides the reduction of portal vein pressure, the highly variable right atrial pressure was the main contributor to different pressure gradients. Thus, immediate post-TIPS measurements do not reliably predict portal hemodynamics during follow-up. These findings need to be further investigated with respect to the corresponding clinical course of the patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-021-03003-z.

Test-Retest Reliability and Consistency of HVPG and Impact on Trial Design: A Study in 289 Patients from 20 Randomized Controlled Trials

BACKGROUND AND AIMS

Portal hypertension (PH) is a major driver for cirrhosis complications. Portal pressure is estimated in practice by the HVPG. The assessment of HVPG changes has been used for drug development in PH. This study aimed at quantifying the test-retest reliability and consistency of HVPG in the specific context of randomized controlled trials (RCTs) for the treatment of PH in cirrhosis and its impact on power calculations for trial design.

APPROACH AND RESULTS

We conducted a search of published RCTs in patients with cirrhosis reporting individual patient-level data of HVPG at baseline and after an intervention, which included a placebo or an untreated control arm. Baseline and follow-up HVPGs in the control groups were extracted after digitizing the plots. We assessed reliability and consistency and the potential impact of study characteristics. We retrieved a total of 289 before and after HVPG measurements in the placebo/untreated groups from 20 RCTs. The time span between the two HVPG measurements ranged between 20 minutes and 730 days. Pre-/post-HVPG variability was lower in studies including only compensated patients; therefore, modeled sample size calculations for trials in compensated cirrhosis were lower than for decompensated cirrhosis. A higher proportion of alcohol-associated cirrhosis and unicentric trials was associated with lower differences between baseline and follow-up measurements. The smallest detectable difference in an individual was 26% and 30% in compensated and decompensated patients, respectively.

CONCLUSIONS

The test-retest reliability of HVPG is overall excellent. Within-individual variance was higher in studies including higher proportions of decompensated patients. These findings should be taken into account when performing power analysis for trials based on the effects on HVPG or when considering HVPG as a tool to guide therapy of PH.

The Role of Hepatic Venous Pressure Gradient in the Management of Cirrhosis

Quantifying the degree of portal hypertension provides useful information to estimate prognosis and to evaluate new therapies for portal hypertension. This quantification is done in clinical practice with the measurement of the hepatic venous pressure gradient. This article addresses the applications of measuring portal pressure in cirrhosis, including the differential diagnosis of portal hypertension; estimation of prognosis in cirrhosis, including preoperative evaluation before hepatic and extrahepatic surgery; assessment of the response to drug therapy (mainly in the context of drug development); and assessing the regression of portal hypertension syndrome.

Nonalcoholic fatty liver disease and portal hypertension

Nonalcoholic fatty liver disease (NAFLD) is a substantial and growing problem worldwide and has become the second most common indication for liver transplantation as it may progress to cirrhosis and develop complications from portal hypertension primarily caused by advanced fibrosis and erratic tissue remodeling. However, elevated portal venous pressure has also been detected in experimental models of fatty liver and in human NAFLD when fibrosis is far less advanced and cirrhosis is absent. Early increases in intrahepatic vascular resistance may contribute to the progression of liver disease. Specific pathophenotypes linked to the development of portal hypertension in NAFLD include hepatocellular lipid accumulation and ballooning injury, capillarization of liver sinusoidal endothelial cells, enhanced contractility of hepatic stellate cells, activation of Kupffer cells and pro-inflammatory pathways, adhesion and entrapment of recruited leukocytes, microthrombosis, angiogenesis and perisinusoidal fibrosis. These pathological events are amplified in NAFLD by concomitant visceral obesity, insulin resistance, type 2 diabetes and dysbiosis, promoting aberrant interactions with adipose tissue, skeletal muscle and gut microbiota. Measurement of the hepatic venous pressure gradient by retrograde insertion of a balloon-tipped central vein catheter is the current reference method for predicting outcomes of cirrhosis associated with clinically significant portal hypertension and guiding interventions. This invasive technique is rarely considered in the absence of cirrhosis where currently available clinical, imaging and laboratory correlates of portal hypertension may not reflect early changes in liver hemodynamics. Availability of less invasive but sufficiently sensitive methods for the assessment of portal venous pressure in NAFLD remains therefore an unmet need. Recent efforts to develop new biomarkers and endoscopy-based approaches such as endoscopic ultrasound-guided measurement of portal pressure gradient may help achieve this goal. In addition, cellular and molecular targets are being identified to guide emerging therapies in the prevention and management of portal hypertension.

Invasive and non-invasive assessment of portal hypertension

Portal hypertension is the central driver of complications in patients with chronic liver diseases and cirrhosis. The diagnosis of portal hypertension has important prognostic and clinical implications. In particular, screening for varices in patients with portal hypertension can effectively reduce the morbidity and mortality of variceal bleeding. In this article, we review the invasive and non-invasive methods to assess portal hypertension. Hepatic venous pressure gradient remains the gold standard to measure portal pressure but is invasive and seldom performed outside expert centers and research settings. In recent years, a number of non-invasive tests of fibrosis have shown good correlation with liver histology. They also show promise in identifying patients with portal hypertension and large varices. As a result, the latest Baveno VI consensus guidelines endorse the use of liver stiffness measurement by transient elastography and platelet count as initial assessment to select patients for varices screening. On the other hand, the performance of non-invasive tests in assessing the response to non-selective beta-blockers or transjugular intrahepatic portosystemic shunting is either suboptimal or unclear.

Potential use of metabolic breath tests to assess liver disease and prognosis: has the time arrived for routine use in the clinic?

The progression of liver disease may be unique among organ system diseases in that progressive fibrosis compromises not only the sufficiency of hepatocyte mass but also impairs blood flow to the liver, resulting in porto-systemic shunting. Although liver biopsy as an assessment of fibrosis has become the key biomarker of and target for new therapies, it is invasive and subject to sampling error, and cannot quantify metabolic function or porto-systemic shunting. Measurement of the hepatic venous pressure gradient accommodates some of the deficiencies of biopsy but requires expertise not widely available and misses minor changes in hepatocellular mass and thereby information about metabolic function. Thus, an unmet need in clinical hepatology remains unfulfilled: a noninvasive biomarker which quantitates both the hepatocellular insufficiency and porto-systemic shunting inherent in progressive hepatic fibrosis. Ideally, such a biomarker should correlate with clinical endpoints including liver-related survival and cirrhotic complications, be performed at the point-of-care, and be affordable and easy to use. This review, an expert opinion, summarizes background and recent data suggesting that metabolic breath tests may now meet these requirements and have a valid place in clinical hepatology to supplant the time-honoured assessment of hepatic fibrosis.