Pressure Gradient Measurement Research Articles

Temperature effect on non-Darcian flow in low-permeability porous media

The Darcy’s law specifies a linear relation between the Darcy velocity of a fluid flow and the pressure gradient that drives the flow. However, in low-permeability porous media, the velocity of a fluid flow exhibits a nonlinear dependence on the imposed pressure gradient, which is referred to as the non-Darcian flow behavior. Temperature has been postulated to affect the threshold pressure gradient of a non-Darcian flow; however, the supporting data is very limited due to the challenges in conducting flow experiments in low-permeability porous media. In this study we for the first time report a systematic measurement of the threshold pressure gradient under various permeabilities and temperatures. The results show that a higher temperature leads to a lower threshold pressure gradient under the same permeability and a faster reduction of the threshold pressure gradient with increasing permeability. The experimental data are fitted to a two-parameter model we previously developed to determine the parameters, h0 and a, which characterize the interfacial fluid-solid interactions and the transition between the Darcy and non-Darcian regimes. Both h0 and a decrease with an increasing temperature. The lower value of h0 under a higher temperature leads to the faster decline of threshold pressure gradient with increasing permeability. This is the first comprehensive experimental study that measured the threshold pressure gradient under multiple different permeabilities and temperatures, which generated the first laboratory dataset of this kind. The experimental data and the model constrained here allow for systematic predictions of both Darcy and non-Darcian flows for a general set of low-permeability porous media under various temperatures and pressure gradients, which have important applications to geological disposal of nuclear waste, hydrocarbon extraction from shale, and contaminant remediation in clay-rich formations.

Womersley's solution for the measurement of volume flow rates in transient laminar flow tubes

The characterization of transient flows within the Reynolds number range of Re = 10–100 and the Womersley number range α = 0.8–10 is required for the ongoing development of green monopropellant thrusters. However, at the ml/min scale flow rates of interest, these measurements are outside the capabilities of current commercial flow meters. It is proposed here that transient flows under the required dynamic conditions can be characterized via Womersley's solution for transient flow in a rigid tube. This solution method requires only the measured transient pressure gradient within a controlled laminar flow section and can be accomplished using existing commercial pressure measurement hardware. Experiments were performed where flow similarity was maintained with the ultimate thruster characterization application, but the radius of the flow passage was increased so that flows could be simultaneously characterized by both the proposed solution method and a commercial ultrasonic flow meter. It was shown that across the range of interest, applying Womersley's solution to a measured pressure gradient was an effective method of transient flow characterization. Additionally, it was shown that non-periodic flows can be characterized except for the initial flow startup transient with solution convergence times approximating the analytical solution to starting flow in a pipe. While these results were expected due to an experimental design matching the assumptions required for Womersley's analytic solution, this work demonstrates that this method is practically feasible as novel instrumentation enabling previously unobtainable measurements.

The Sequential Application of Baveno VII Criteria and VITRO Score Improves Diagnosis of Clinically Significant Portal Hypertension

Baveno VII proposed liver stiffness measurement (LSM)/platelet count (PLT)-based criteria ('ruled out,' LSM ≤15 kPa plus PLT ≥150 G/L; 'ruled in': LSM ≥25 kPa) for clinically significant portal hypertension (CSPH) in compensated advanced chronic liver disease (cACLD). However, a substantial proportion of patients remains 'unclassified.' Patients with evidence of cACLD (LSM ≥10 kPa) undergoing hepatic venous pressure gradient (HVPG) measurement at the Vienna General Hospital 2004 to 2021 (derivation [2004-2016], n= 221; validation [2017-2021], n= 81) were included. The performance of noninvasive tests (NITs) including von Willebrand factor antigen to PLT ratio (VITRO) for the detection of CSPH (HVPG ≥10 mmHg) were evaluated. Overall, viral hepatitis was the predominant (50.7%) etiology, followed by alcoholic liver disease (15.2%) and nonalcoholic steatohepatitis (13.2%); CSPH prevalence was 62.3%. In the derivation cohort, 45.7% were 'unclassified' according to Baveno VII criteria; in this group, VITRO showed an excellent diagnostic performance for the detection of CSPH (area under the receiver operating curve, 0.909; 95% confidence interval, 0.823-0.965). VITRO ≤1.5 and ≥2.5 ruled out (sensitivity, 97.7%; negative predictive value, 97.5%) and ruled in (specificity, 94.7%; positive predictive value, 91.2%), respectively, CSPH in patients who were 'unclassifiable' by Baveno VII criteria. The application of a sequential Baveno VII-VITRO algorithm reallocated 73% and 70% of 'unclassified' patients to the 'ruled in' and 'ruled out' group, respectively, while maintaining high sensitivity and negative predictive value and specificity and positive predictive value in the derivation and validation cohort, respectively. No patient allocated to the 'CSPH ruled out' group by the Baveno VII-VITRO algorithm developed decompensation within 5 years, whereas 5-year decompensation rates were negligible (4%) and substantial (23.9%) among 'unclassified' and 'CSPH ruled in' patients, respectively. The sequential application of VITRO in patients with cACLD who were 'unclassifiable' with regard to CSPH by Baveno VII criteria substantially decreased the number of 'unclassifiable' patients to <15% and refined prognostication.

Spleen stiffness in patients with chronic liver disease evaluated by 2-D shear wave elastography with ultrasound multiparametric imaging.

The novel 2-D shear wave elastography (2D-SWE) can measure two ultrasound parameters: shear wave dispersion (SWD) and shear wave speed (SWS). We investigated the ability of 2D-SWE in measuring spleen stiffness using ultrasound multiparametric imaging. This cross-sectional study included patients with chronic liver disease who underwent esophagogastroduodenoscopy and ultrasonographic examinations of the spleen between September 2018 and December 2021. In total, 157 patients were enrolled in this study: 81 and 67 patients were included in the pilot set for hepatic venous pressure gradient (HVPG) measurements and validation cohort without HVPG measurements, respectively. To confirm reproducibility between the two examiners, an additional 30 patients were enrolled. The Bland-Altman plots revealed no significant bias in the SWD as measured by two examiners. The splenic SWS (r=0.752) and SWD (r=0.444) were correlated with the HVPG. Regarding high-risk varices, as per the Youden index, the cut-off value for splenic SWS was 3.30m/s, with a sensitivity of 85.7%, specificity of 92.5%, positive predictive value of 85.7%, and negative predictive value of 92.4% in the pilot set. In the validation set, good diagnostic performance by the splenic SWS was observed. However, SWD did not perform as well as SWS. The splenic SWS, measured using ultrasound multiparametric imaging, was closely correlated with the HVPG. Thus, SWS is a useful predictive marker for high-risk varices.

S1109 General vs Monitored Anesthesia Time: Is One Preferred for EUS-Guided Portal Pressure Gradient Measurements and Liver Biopsies?

Introduction: EUS-guided portal pressure gradient (PPG) measurement and EUS guided liver biopsies are well tolerated procedures under anesthesia, but it is unclear which anesthesia modality, monitored anesthesia care (MAC) or general anesthesia (GA), is superior for performing these cases. We aimed to describe our centers’ experiences and approach to EUS-guided PPG and liver biopsy from an anesthesia perspective and compared the two anesthesia modalities in terms of procedure duration, efficacy, and safety. Methods: This was a retrospective review of all consecutive patients who underwent EUS-guided PPG measurement and/or liver biopsies at a single tertiary center between June 2021 and May 2022. All procedures were done with an anesthesiologist attending and/or a resident/nurse. After initial experience with GA, our center largely switched to MAC for these cases. In the last 40 cases, 82% were done with MAC. Demographic data, scope time, anesthesia time, technical success rate, and adverse events post procedure for each patient were noted. Statistical analysis was performed using student t-testing. Results: We have a total of 73 patients who underwent EUS guided PPG measurement and/or liver biopsy, with 30 (54%) having undergone only PPG measurement. The mean age was 51, with 56 (77%) patients being female and mean BMI as 37. The clinical indication for most patients 60 (82%) in undergoing the EUS procedure was for evaluation of underlying NAFLD/NASH. No differences in basic demographics was found between the MAC and GA cohorts. The mean scope time for MAC vs GA was 38.2 ± 14.2 and 47.3 ± 14.5 minutes respectively for patients who underwent both EUS-PPG and liver biopsy. The timing of endoscopy was comparable between the two modalities (p=0.013). The mean anesthesia time for MAC vs GA was 57.1 ± 14.9 and 81.6 ± 14.9 minutes respectively, with MAC being shorter by 25 minutes (p= < 0.001). Similar comparisons were made for patients who underwent EUS-PPG alone. Technical success was 100% for all cases, and there was only one reported adverse event of a patient who reported transient shortness of breath post-extubation from GA who underwent EUS-PPG alone. This was resolved within a few hours with close monitoring. (Table) Conclusion: Our results show that MAC was superior in terms of anesthesia time as compared to GA. Both anesthesia modalities demonstrated excellent and comparable safety and efficacy. Table 1. - Procedure and Anesthesia time for EUS guided PPG measurement and Liver Biopsy Table a EUS guided PPG measurement (with liver biopsy) Mean Mac(n=20) GA (N=23) p value Procedure time (mins) 38.2 ± 14.2 47.3 ± 14.5 0.013 Anesthesia time (mins) 57.1 ± 14.9 81.6 ± 14.9 Table b EUS guided PPG measurement (without liver biopsy) Mean MAC (N=13) GA (N=17) p value Procedure time (mins) 37.7 ± 14.5 46.9 ± 14.5 0.011 Anesthesia time (mins) 58.1 ± 15.5 81.9 ± 15.5 < 0.001 Table c Mean intubation time with GA (n=23 )( with liver biopsy) 66.3 ± 14.6 Mean intubation time in minutes with GA (n= 17) ( without liver biopsy) 66 ± 15.3

Assessment of portal hypertension severity using machine learning models in patients with compensated cirrhosis

In individuals with compensated advanced chronic liver disease (cACLD), the severity of portal hypertension (PH) determines the risk of decompensation. Invasive measurement of the hepatic venous pressure gradient (HVPG) is the diagnostic gold standard for PH. We evaluated the utility of machine learning models (MLMs) based on standard laboratory parameters to predict the severity of PH in individuals with cACLD. A detailed laboratory workup of individuals with cACLD recruited from the Vienna cohort (NCT03267615) was utilised to predict clinically significant portal hypertension (CSPH, i.e., HVPG ≥10mmHg) and severe PH (i.e., HVPG ≥16mmHg). The MLMs were then evaluated in individual external datasets and optimised in the merged cohort. Among 1,232 participants with cACLD, the prevalence of CSPH/severe PH was similar in the Vienna (n= 163, 67.4%/35.0%) and validation (n= 1,069, 70.3%/34.7%) cohorts. The MLMs were based on 3 (3P: platelet count, bilirubin, international normalised ratio) or 5 (5P:+cholinesterase,+gamma-glutamyl transferase,+activated partial thromboplastin time replacing international normalised ratio) laboratory parameters. The MLMs performed robustly in the Vienna cohort. 5P-MLM had the best AUCs for CSPH (0.813) and severe PH (0.887) and compared favourably to liver stiffness measurement (AUC: 0.808). Their performance in external validation datasets was heterogeneous (AUCs: 0.589-0.887). Training on the merged cohort optimised model performance for CSPH (AUCs for 3P and 5P: 0.775 and 0.789, respectively) and severe PH (0.737 and 0.828, respectively). Internally trained MLMs reliably predicted PH severity in the Vienna cACLD cohort but exhibited heterogeneous results on external validation. The proposed 3P/5P online tool can reliably identify individuals with CSPH or severe PH, who are thus at risk of hepatic decompensation. We used machine learning models based on widely available laboratory parameters to develop a non-invasive model to predict the severity of portal hypertension in individuals with compensated cirrhosis, who currently require invasive measurement of hepatic venous pressure gradient. We validated our findings in a large multicentre cohort of individuals with advanced chronic liver disease (cACLD) of any cause. Finally, we provide a readily available online calculator, based on 3 (platelet count, bilirubin, international normalised ratio) or 5 (platelet count, bilirubin, activated partial thromboplastin time, gamma-glutamyltransferase, choline-esterase) widely available laboratory parameters, that clinicians can use to predict the likelihood of their patients with cACLD having clinically significant or severe portal hypertension.

Endoscopic ultrasound-guided portal pressure gradient measurement.

Endoscopic ultrasound-guided portal pressure gradient measurement.

Alpha-1 antitrypsin Pi∗Z allele is an independent risk factor for liver transplantation and death in patients with advanced chronic liver disease

Background & AimsAlpha-1 antitrypsin (AAT) deficiency causes/predisposes individuals to advanced chronic liver disease (ACLD). However, the role of the SERPINA1 Pi∗Z allele in patients who have already progressed to ACLD is unclear. Thus, we aimed to evaluate the impact of the Pi∗Z allele on the risk of liver transplantation/liver-related death in patients with ACLD, while adjusting for the severity of liver disease at inclusion.MethodsA total of 1,118 patients with ACLD who underwent hepatic venous pressure gradient (HVPG) measurement and genotyping for the Pi∗Z/Pi∗S allele at the Vienna Hepatic Hemodynamic Lab were included in this retrospective analysis. The outcome of interest was liver transplantation/liver-related death, while non-liver-related death and removal/suppression of the primary etiological factor were considered as competing risks.ResultsViral hepatitis was the most common etiology (44%), followed by alcohol-related (31%) and non-alcoholic fatty liver disease (11%). Forty-two (4%) and forty-six (4%) patients harboured the Pi∗Z and Pi∗S variants, respectively. Pi∗Z carriers had more severe portal hypertension (HVPG: 19±6 vs.15±7 mmHg; p <0.001) and hepatic dysfunction (Child-Turcotte-Pugh: 7.1±1.9 vs. 6.5±1.9 points; p = 0.050) at inclusion, compared to non-carriers. Contrarily, the Pi∗S allele was unrelated to liver disease severity. In competing risk regression analysis, harbouring the Pi∗Z allele was significantly associated with an increased probability of liver transplantation/liver-related death, even after adjusting for liver disease severity at inclusion. The detrimental impact of the common Pi∗MZ genotype (adjusted subdistribution hazard ratio: ≈1.56 vs. Pi∗MM) was confirmed in a fully adjusted subgroup analysis. In contrast, Pi∗S carriers had no increased risk of events.ConclusionGenotyping for the Pi∗Z allele identifies patients with ACLD at increased risk of adverse liver-related outcomes, thereby improving prognostication. Therapies targeting the accumulation of abnormal AAT should be evaluated as disease-modifying treatments in Pi∗Z allele carriers with ACLD.Lay summaryAlpha-1 antitrypsin deficiency is a genetic disease that affects the lung and the liver. Carrying two dysfunctional copies of the gene causes advanced liver disease. Harbouring one dysfunctional copy increases disease severity in patients with other liver illness. However, the significance of this genetic defect in patients who already suffer from advanced liver disease is unclear. Our study found that harbouring at least one dysfunctional copy of the alpha-1 antitrypsin gene increases the risk of requiring a liver transplantation or dying from a liver disease. This indicates the need for medical therapies aimed at treating the hepatic consequences of this genetic defect.

Concomitant mitral regurgitation in patients with low-gradient aortic stenosis: an analysis from the German Aortic Valve Registry

BackgroundPatients with severe aortic stenosis (AS) frequently presented mitral regurgitation (MR), which may interfere with the standard echocardiographic measurements of mean pressure gradient (MPG), flow velocity, and aortic valve area (AVA).AimsHerein we investigated the prevalence and severity of MR in patients with severe AS and its role on the accuracy of the standard echocardiographic parameters of AS quantification.MethodsOf all patients with severe AS undergoing transcatheter or surgical aortic valve replacement enrolled in the German Aortic Registry from 2011 to 2017, 119,641 were included in this study. The population was divided based on the values of left ventricular ejection fraction ([LVEF] > 50%, LVEF 31–50%, and LVEF ≤ 30%] and AVA (0.80 to ≤ 1.00 cm2, 0.60 to < 0.80 cm2, 0.40 to < 0.60 cm2, and 0.20 to < 0.40 cm2).ResultsOverall, 77,890 (65%) patients with mild to-moderate and 4262 (4%) with severe MR were compared with 37,489 (31%) patients without MR. Patients with mild-to-moderate and severe MR presented significantly lower mPG (ΔmPG [95%CI] − 1.694 mmHg [− 2.123 to − 1.265], p < 0.0001 and − 6.954 mmHg [− 7.725 to − 6.183], p < 0.0001, respectively), that increased with LVEF impairment. Conversely, AVA did not differ (severe versus no MR: ΔAVA [95%CI]: − 0.007cm2 [− 0.023 to 0.009], p = 0.973). Increasing MR severity was associated with significant mPG reduction throughout all AVA strata, causing a low-gradient pattern, that manifested since the early stages of severe AS (LVEF > 50%: AVA 0.80 to 1.00 cm2; LVEF 31–50%: AVA 0.60 to 0.80 cm2).ConclusionsIn patients with severe AS, concomitant MR is common, contributes to the onset of a low-gradient AS pattern, and affects the diagnostic accuracy of flow-dependent AVA measurements. In this setting, a multimodality, AVA-centric approach should be implemented.Graphical abstractIn patients with severe aortic stenosis, concomitant mitral regurgitation contributes to the onset of a low-gradient pattern, warranting a multimodality, and AVA-centric diagnostic approach.

Hepatic venous pressure gradient in sinusoidal obstruction syndrome: Diagnostic value and link with histological lesions

Background & AimsLiver sinusoidal obstruction syndrome (SOS) is a well-established complication of myeloablative conditioning regimens used in hematopoietic stem cell transplantation. Hepatic venous pressure gradient (HVPG) >10 mmHg was described as an accurate diagnostic tool for SOS in the 1990s. However, epidemiology and presentation of SOS have dramatically changed. Moreover, elementary histological lesions influencing HVPG are unknown.MethodsWe retrospectively analyzed the charts of all patients who underwent transjugular liver biopsy with HVPG measurement for a clinical suspicion of SOS at our center. Two expert pathologists unaware of the presence or absence of SOS reviewed all liver samples and graded elementary histological lesions according to a semi-quantitative scoring defined a priori.ResultsOut of the 77 included patients, the 30 patients with SOS had higher HVPG than the 47 patients without SOS (median 14 mmHg [IQR 10-18], vs. 6 mmHg [3-9], respectively p <0.001). HVPG >10 mmHg had a specificity of 78% and a positive predictive value of 66% for the diagnosis of SOS. However, almost 40% of the patients with SOS had an HVPG ≤10 mmHg. HVPG correlated with sinusoidal congestion (r = 0.57; p = 0.001) and hepatocyte necrosis (r = 0.42; p = 0.02), but not with other lesions.ConclusionEven though HVPG is higher in patients with SOS, low HVPG values do not rule out SOS. Thus, HVPG cannot be used alone, and should be combined with transjugular liver biopsy, for the diagnosis of SOS.Lay summaryHepatic venous pressure gradient >10 mmHg has been described as an accurate tool for the diagnosis of liver sinusoidal obstruction syndrome after hematopoietic stem cell transplantation. This study shows that the sensitivity and specificity of hepatic venous pressure gradient measurement for sinusoidal obstruction syndrome are insufficient, so that liver pressure measurement should be combined with a liver biopsy in this setting.

Multivariable Technique for the Evaluation of the Trans-stenotic Pressure Gradient.

This study establishes a reliable image-based multivariable technique for measuring the trans-stenotic pressure gradient. A self-made in vitro steady flow model based on adjustable velocities and stenotic properties were used as the experimental subject. The pre-stenotic flow velocity, severity, and length of the stenosis were used as the input variables. Based on equations used to fit the plots of the physically measured pressure gradient values versus each input variable, a multivariable formula for the pressure gradient measurement could then be derived. The flow model was scanned using velocity-encoded phase-contrast magnetic resonance imaging (PC-MRI) to validate the derived formula while simultaneously measuring the trans-stenotic pressure gradient. The correlation between the physically-measured pressure gradient values and the pressure gradient values calculated using the new formula were subsequently analyzed. The results of linear regression analysis using the physically measured pressure gradient values for the new method were compared to values obtained using the simplified Bernoulli equation (R2, 0.991, and 0.975, respectively). In a paired t-test, no statistically significant difference was found between the new method and the physical measurements. The derived multivariable technique was found to reliably measure the trans-stenotic pressure gradient, with better performance than a traditional procedure based on the simplified Bernoulli equation.

A Combined Baveno VII and Spleen Stiffness Algorithm to Improve the Noninvasive Diagnosis of Clinically Significant Portal Hypertension in Patients With Compensated Advanced Chronic Liver Disease.

A noninvasive diagnosis of clinically significant portal hypertension (CSPH) has important prognostic and therapeutic implications for patients with compensated advanced chronic liver disease. We aimed to validate and improve the available algorithms for the CSPH diagnosis by evaluating spleen stiffness measurement (SSM) in patients with compensated advanced chronic liver disease. This is a retrospective study including patients with liver stiffness measurement (LSM) ≥10 kPa, no previous decompensation, and available measurements of hepatic venous pressure gradient, LSM, and SSM by transient elastography referring to our center in Bologna. The diagnostic algorithms were adequate if negative and positive predictive values were >90% when ruling out and ruling in CSPH, respectively; these models were validated in a cohort from Verona. The 5-year decompensation rate was reported. One hundred fourteen patients were included in the derivation cohort. The Baveno VII diagnostic algorithm (LSM ≤15 kPa + platelet count ≥150 × 10 9 /L to rule out CSPH and LSM >25 kPa to rule in CSPH) was validated; however, 40%-60% of the patients remained in the gray zone. The addition of SSM (40 kPa) to the model significantly reduced the gray zone to 7%-15%, maintaining adequate negative and positive predictive values. The diagnostic algorithms were validated in a cohort of 81 patients from Verona. All first decompensation events occurred in the "rule-in" zone of the model including SSM. The addition of SSM significantly improves the clinical applicability of the algorithm based on LSM and platelet count for CSPH diagnosis. Our models can be used to noninvasively identify candidates for nonselective beta-blocker treatment and patients at a high risk of decompensation.

Evaluation of the OpSens OptoWire III and Novel TAVR Algorithm to Measure Pressure Gradient During TAVR.

We aim to establish the degree of agreement related to gradient measurement during transcatheter aortic valve replacement (TAVR) between the OpSens OptoWire III and its new proprietary TAVR algorithm and hemodynamic value derived by catheterization and echocardiogram (transthoracic echocardiogram and transesophageal echocardiogram). The current study was a prospective, single-arm, single-center study. All subjects underwent hemodynamic assessment before and after TAVR using standard hemodynamic assessment using 2 pigtails, transthoracic echocardiogram, transesophageal echocardiogram, and the OpSens OptoWire III. The primary end point was the final post-TAVR mean gradient correlation between OpSens OptoWire III and hemodynamic values derived by catheterization. Between July 2021 and September 2021, 20 patients were enrolled. The median age was 79 [6.5] years, and 9 (45%) patients were female. The mean gradient before TAVR derived by 2-pigtail technique and the mean gradient using the OpSens OptoWire III were similar (35 ± 14 mm Hg vs 35 ± 14 mm Hg, P = 1.00), with an absolute mean difference of 2.2 ± 3.5 mm Hg and a strong correlation (r = 0.96, P < .0001). After TAVR, the mean gradient derived by 2-pigtail technique and the mean gradient using the OpSens OptoWire III were similar (2.2 ± 3.5 vs 2.8 ± 2.7, P = .16), with an absolute mean difference of 1.2 ± 1.3 mm Hg and a strong correlation (r = 0.89, P < .0001). Hemodynamic assessment derived by the OpSens OptoWire III wire and its new TAVR algorithm demonstrated excellent correlation with measurements derived by 2 pigtails both before and after TAVR. Integration of this new technology within a dedicated TAVR wire with live hemodynamic assessment could bring meaningful value to TAVR operators.

Measuring the Gradient of Sound Pressure Directly Via Flexoelectricity

In this work, we propose the design of a flexoelectric sensor, which can measure sound-pressure gradient directly. It is found that the sensitivity of sound-pressure gradient of the flexoelectric sensor has a wide band for low working frequencies. Our theoretical and experimental results indicate that the position of sound sources can be predicted based on the measured sound-pressure gradients of three flexoelectric sensors, which are perpendicular to each other. Moreover, different from the previous design for a piezoelectric sensor array, only three flexoelectric sensors are needed to determine the orientation of sound sources. The flexoelectric sensor proposed here may provide an alternative way for the pressure-gradient measurement.

Portal Pressure Measurements: Locations, Implications, and State of the Art

Portal hypertension defined as pressure within the portal venous system is an important event in the evolution of cirrhosis. With the development of clinically significant portal hypertension, there is increased risk of developing gastroesophageal varices and hepatic decompensation. Endoscopic evaluation of esophageal and gastric varices and hepatic venous pressure gradient (HVPG) measurement are gold standard methods for evaluating portal hypertension. Additionally, measurement of HVPG is important in prognostication and assessing efficacy of pharmacotherapy. New state-of-the-art noninvasive techniques are available for diagnosis and assessment of portal hypertension severity. While some of these are validated for larger clinical application, others are still experimental. In this review, we have discussed invasive and noninvasive portal hypertension measurement techniques.

MR elastography outperforms shear wave elastography for the diagnosis of clinically significant portal hypertension.

Portal hypertension (PH) is associated with complications such as ascites and esophageal varices and is typically diagnosed through invasive hepatic venous pressure gradient (HVPG) measurement, which is not widely available. In this study, we aim to assess the diagnostic performance of 2D/3D MR elastography (MRE) and shear wave elastography (SWE) measures of liver and spleen stiffness (LS and SS) and spleen volume, to noninvasively diagnose clinically significant portal hypertension (CSPH) using HVPG measurement as the reference. In this prospective study, patients with liver disease underwent 2D/3D MRE and SWE of the liver and spleen, as well as HVPG measurement. The correlation between MRE/SWE measures of LS/SS and spleen volume with HVPG was assessed. ROC analysis was used to determine the utility of MRE, SWE, and spleen volume for diagnosing CSPH. Thirty-six patients (M/F 22/14, mean age 55 ± 14 years) were included. Of the evaluated parameters, 3D MRE SS had the strongest correlation with HVPG (r = 0.686, p < 0.001), followed by 2D MRE SS (r = 0.476, p = 0.004). 3D MRE SS displayed the best performance for diagnosis of CSPH (AUC = 0.911) followed by 2D MRE SS (AUC = 0.845) and 3D MRE LS (AUC = 0.804). SWE SS showed poor performance for diagnosis of CSPH (AUC = 0.583) while spleen volume was a fair predictor (AUC = 0.738). 3D MRE SS was significantly superior to SWE LS/SS (p ≤ 0.021) for the diagnosis of CSPH. SS measured with 3D MRE outperforms SWE for the diagnosis of CSPH. SS appears to be a useful biomarker for assessing PH severity. These results need further validation. • Spleen stiffness measured with 2D and 3D MR elastography correlates significantly with hepatic venous pressure gradient measurement. • Spleen stiffness measured with 3D MR elastography demonstrates excellent performance for the diagnosis of clinically significant portal hypertension (AUC 0.911). • Spleen stiffness measured with 3D MR elastography outperforms liver and spleen stiffness measured with shear wave elastography for diagnosis of clinically significant portal hypertension.

Role of endoscopic ultrasound in vascular interventions: Where are we now?

From a mere diagnostic tool to an imperative treatment modality, endoscopic ultrasound (EUS) has evolved and revolutionized safer efficient options for vascular interventions. Currently it is an alternative treatment option in the management of gastrointestinal bleeding, primarily variceal type bleeding. Conventional treatment option prior to EUS incorporation had limited efficiency and high adverse events. The characterization and detail provided by EUS gives a cutting edge towards a holistically successful management choice. Data indicates that EUS-guided combination therapy of coil embolization and glue injection has the higher efficacy for the treatment of varices. Conversely, similar treatment options that exist for esophageal and other ectopic variceal bleeding was also outlined. In conclusion, many studies refer that a combination therapy of coil and glue injection under EUS guidance provides higher technical success with fewer recurrence and adverse events, making its adaptation in the guideline extremely favorable. Endo-hepatology is a novel disciple with a promising future outlook, we reviewed topics regarding portal vein access, pressure gradient measurement, and thrombus biopsy that are crucial interventions as alternative of radiological procedures. The purpose of this review is to provide an update on the latest available evidence in the literature regarding the role of EUS in vascular interventions. We reviewed the role of EUS in variceal bleeding in recent studies, especially gastric varices and novel approaches aimed at the portal vein.

A Novel SAVE Score to Stratify Decompensation Risk in Compensated Advanced Chronic Liver Disease (CHESS2102): An International Multicenter Cohort Study.

INTRODUCTION:In patients with compensated advanced chronic liver disease (cACLD), the invasive measurement of hepatic venous pressure gradient is the best predictor of hepatic decompensation. This study aimed at developing an alternative risk prediction model to provide a decompensation risk assessment in cACLD.METHODS:Patients with cACLD were retrospectively included from 9 international centers within the Portal Hypertension Alliance in China (CHESS) network. Baseline variables from a Japanese cohort of 197 patients with cACLD were examined and fitted a Cox hazard regression model to develop a specific score for predicting hepatic decompensation. The novel score was validated in an external cohort (n = 770) from 5 centers in China, Singapore, Korea, and Egypt, and was further assessed for the ability of predicting clinically significant portal hypertension in a hepatic venous pressure gradient cohort (n = 285).RESULTS:In the derivation cohort, independent predictors of hepatic decompensation were identified including Stiffness of liver, Albumin, Varices, and platElets and fitted to develop the novel score, termed “SAVE” score. This score performed significantly better (all P < 0.05) than other assessed methods with a time-dependent receiver operating characteristic curve of 0.89 (95% confidence interval [CI]: 0.83–0.94) and 0.83 (95% CI: 0.73–0.92) in the derivation and validation cohorts, respectively. The decompensation risk was best stratified by the cutoff values at −6 and −4.5. The 5-year cumulative incidences of decompensation were 0%, 24.9%, and 69.0% in the low-risk, middle-risk, and high-risk groups, respectively (P < 0.001). The SAVE score also accurately predicted clinically significant portal hypertension (AUC, 0.85 95% CI: 0.80–0.90).DISCUSSION:The SAVE score can be readily incorporated into clinical practice to accurately predict the individual risk of hepatic decompensation in cACLD.

Hepatic venous pressure gradient (HVPG) measurement: Tips and pitfalls of hepatic venous catheterization

Hepatic venous pressure gradient (HVPG) measurement: Tips and pitfalls of hepatic venous catheterization

Tolerance and acceptance of hepatic venous pressure gradient measurement in cirrhosis (CHESS1904): An international multicenter study

AbstractAimTo determine the tolerance and acceptance of hepatic venous pressure gradient (HVPG) measurements in patients with liver cirrhosis.MethodsThis prospective international multicenter study included 271 patients with cirrhosis who were scheduled to undergo HVPG measurement between October 2019 and June 2020. Data related to the tolerance and acceptance of HVPG measurements were collected using descriptive questionnaires.ResultsHVPG measurements were technically successful in all 271 patients, with 141 (52.0%) undergoing HVPG measurement alone. The complication rate was 0.4%. Postoperative pain was significantly lower than preoperative expected pain (p &lt; 0.001) and intraoperative pain (p &lt; 0.001), and intraoperative pain was also significantly lower than preoperative expected pain (p = 0.036). No, mild, moderate, severe, and intolerable discomfort scores were reported by 36.9%, 44.6%, 11.1%, 6.3%, and 0.4% of these patients, respectively, during HVPG measurement and by 54.6% 32.5%, 11.4%, 1.5%, and 0%, respectively, after HVPG measurement. Of these patients, 39.5% had little understanding and 10% had no understanding of the value of HVPG measurement, with 35.1% and 4.1% regarding HVPG measurements as being of little or no help, respectively. Most patients reported that they would definitely (15.5%), probably (46.9%), or possibly (29.9%) choose to undergo additional HVPG measurements again, and 62.7% regarded the cost of the procedure as acceptable.ConclusionHVPG measurement was safe and well‐tolerated in patients with cirrhosis, but patient education and communication are warranted to improve the acceptance of this procedure.