Portal Venous Pulsatility Index: A Novel Biomarker for Diagnosis of High-Risk Nonalcoholic Fatty Liver Disease

Ablation of Hepatic Asah1 Gene Disrupts Hepatic Lipid Homeostasis and Promotes Fibrotic Nonalcoholic Steatohepatitis in Mice

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of chronic liver conditions, ranging from simple steatosis to nonalcoholic steatohepatitis, which may progress to fibrosis/cirrhosis. Here, the GSE163211 data set was analyzed, and Asah1 (encoding acid ceramidase) was identified as a crucial lysosomal gene that positively correlated with NAFLD stages in obese patients. To evaluate the role of Asah1 in the progression of NAFLD, Asah1fl/fl/Albcre mice (hepatocyte-specific deletion of Asah1) and Asah1 floxed (Asah1fl/fl/wild-type) mice were fed with either a normal diet or a high-fat, high-cholesterol paigen diet (PD) for 20 weeks. Hepatocyte-specific Asah1 ablation markedly aggravated PD-induced hepatic steatosis, hepatitis, and apoptosis, and resulted in marked fibrotic changes. In addition, Asah1 gene ablation exacerbated PD-induced portal venous hemodynamic abnormality. In cultured hepatocytes, Asah1 gene knockdown resulted in increased ceramide and cholesterol levels but did not affect triglyceride level. Knocking down Asah1 gene also exhibited broad impacts on lipid homeostasis pathways, including lipogenesis, fatty acid uptake, fatty acid oxidation, and lipid transport. Furthermore, Asah1 knockdown resulted in increased endoplasmic reticulum stress and lipid droplet biogenesis. Finally, Asah1 gene knockdown impaired chaperone-mediated autophagy. These results suggest that Asah1 functions as an important regulator of hepatic lipid homeostasis, and its deficiency exacerbates hepatocyte lipotoxicity and injury, and promotes the development of fibrotic nonalcoholic steatohepatitis.

Decoding VExUS: a practical guide for excelling in point-of-care ultrasound assessment of venous congestion

Venous congestion, often associated with elevated right atrial pressure presents a clinical challenge due to its varied manifestations and potential organ damage. Recognizing the manifestations of venous congestion through bedside physical examination or laboratory tests can be challenging. Point-of-care ultrasound (POCUS) is emerging as a valuable bedside tool for assessing venous congestion, with the Venous Excess Ultrasound (VExUS) technique gaining prominence. VExUS facilitates non-invasive quantification of venous congestion, relying on measurements of the inferior vena cava (IVC) size and Doppler assessments of the hepatic vein (HV), portal vein (PV), and intrarenal vein, thereby providing real-time insights into hemodynamic status and guiding therapeutic interventions. The grading system outlined in VExUS aids in stratifying the severity of congestion. However, achieving proficiency in VExUS requires a comprehensive understanding of Doppler techniques and their clinical applications. This review article provides practical guidance on performing VExUS, encompassing equipment requirements, preparation, machine settings, and examination techniques for assessing the inferior vena cava (IVC), hepatic vein (HV), portal vein (PV), and intrarenal vein. Potential pitfalls and troubleshooting strategies are discussed to ensure accurate interpretation of Doppler waveforms.

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

The Portal Venous Pulsatility Index and Main Portal Vein Diameter as Surrogate Markers for Liver Fibrosis in Nonalcoholic Fatty Liver Disease and Metabolic-Dysfunction-Associated Steatotic Liver Disease

(1) Background: Despite numerous noninvasive methods for assessing liver fibrosis, effective ultrasound parameters remain limited. We aimed to identify easily measurable ultrasound parameters capable of predicting liver fibrosis in patients with nonalcoholic fatty liver disease (NAFLD) and metabolic-dysfunction-associated steatotic liver disease (MASLD); (2) Methods: The data of 994 patients diagnosed with NAFLD via ultrasound at the Armed Forces Goyang Hospital were retrospectively collected from June 2022 to July 2023. A liver stiffness measurement (LSM) ≥ 8.2 kPa was classified as significant fibrosis. Liver steatosis with cardiometabolic risk factors was defined as MASLD. Two ultrasound variables, the portal venous pulsatility index (VPI) and main portal vein diameter (MPVD), were measured; (3) Results: Of 994 patients, 68 had significant fibrosis. Significant differences in VPI (0.27 vs. 0.34, p < 0.001) and MPVD (10.16 mm vs. 8.98 mm, p < 0.001) were observed between the fibrotic and non-fibrotic groups. A logistic analysis adjusted for age and body mass index (BMI) revealed that only VPI (OR of 0.955, p = 0.022, VPI on a 0.01 scale) and MPVD (OR of 1.501, p < 0.001) were significantly associated with significant liver fibrosis. In the MASLD cohort (n = 939), VPI and MPVD were associated with significant fibrosis. To achieve better accuracy in predicting liver fibrosis, we established a nomogram that incorporated MPVD and VPI. The established nomogram was validated in the test cohort, yielding an area under the receiver operating characteristic curve of 0.821 for detecting significant liver fibrosis; (4) Conclusions: VPI and MPVD, as possible surrogate markers, are useful in predicting significant fibrosis in patients with NAFLD and MASLD.

Variation in hepatic segmental portal venous pulsed wave Doppler flow distribution in patients with NAFLD: A pilot study

Purpose

To evaluate the segmental variations in portal venous pulsed wave colour Doppler flow velocity in patients with moderate to severe non-alcoholic fatty liver disease in comparison with healthy controls.

Materials and Methods

In this prospective, observational, case-control study, the maximum velocity of all the segmental branches of portal vein were evaluated on colour Doppler in patients with moderate to severe non-alcoholic fatty liver disease, and the values were compared between three groups (1) Healthy controls (n = 30), (2) non-alcoholic fatty liver disease group, that is moderate to severe fatty liver without features of portal hypertension (n = 32) and (3) non-alcoholic steatohepatitis-portal hypertension group, that is those non-alcoholic fatty liver disease patients with features of portal hypertension (n = 13).

Results

Compared to controls, non-alcoholic fatty liver disease group showed a lower velocity in all the eight segments of liver. The ratio of segment 2 to segment 7 peak portal vein maximum velocity was significantly higher in non-alcoholic fatty liver disease (1.03 ± 0.21) compared to controls (0.90 ± 0.17) and even higher in non-alcoholic steatohepatitis-Portal hypertension group (1.83 ± 0.40) with p value of 0.003.

Conclusion

Our study demonstrates the occurrence of flow redistribution occurring in cases of non-alcoholic fatty liver disease patients with the left lobe receiving higher portal venous flow. This flow redistribution was even more pronounced in a subset of non-alcoholic fatty liver disease patients who developed features of portal hypertension.

The Future Is Beyond Bright: The Evolving Role of Quantitative US for Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a common cause of morbidity and mortality. Nonfocal liver biopsy is the historical reference standard for evaluating NAFLD, but it is limited by invasiveness, high cost, and sampling error. Imaging methods are ideally situated to provide quantifiable results and rule out other anatomic diseases of the liver. MRI and US have shown great promise for the noninvasive evaluation of NAFLD. US is particularly well suited to address the population-level problem of NAFLD because it is lower-cost, more available, and more tolerable to a broader range of patients than MRI. Noninvasive US methods to evaluate liver fibrosis are widely available, and US-based tools to evaluate steatosis and inflammation are gaining traction. US techniques including shear-wave elastography, Doppler spectral imaging, attenuation coefficient, hepatorenal index, speed of sound, and backscatter-based estimation have regulatory clearance and are in clinical use. New methods based on channel and radiofrequency data analysis approaches have shown promise but are mostly experimental. This review discusses the advantages and limitations of clinically available and experimental approaches to sonographic liver tissue characterization for NAFLD diagnosis as well as future applications and strategies to overcome current limitations.

Proceedings of the 2022 UAB CRRT Academy: Non-Invasive Hemodynamic Monitoring to Guide Fluid Removal with CRRT and Proliferation of Extracorporeal Blood Purification Devices

In 2022, we celebrated the 15th anniversary of the University of Alabama at Birmingham (UAB) Continuous Renal Replacement Therapy (CRRT) Academy, a 2-day conference attended yearly by an international audience of over 100 nephrology, critical care, and multidisciplinary trainees and practitioners. This year, we introduce the proceedings of the UAB CRRT Academy, a yearly review of select emerging topics in the field of critical care nephrology that feature prominently in the conference. First, we review the rapidly evolving field of non-invasive hemodynamic monitoring and its potential to guide fluid removal by renal replacement therapy (RRT). We begin by summarizing the accumulating data associating fluid overload with harm in critical illness and the potential for harm from end-organ hypoperfusion caused by excessive fluid removal with RRT, underscoring the importance of accurate, dynamic assessment of volume status. We describe four applications of point-of-care ultrasound used to identify patients in need of urgent fluid removal or likely to tolerate fluid removal: lung ultrasound, inferior vena cava ultrasound, venous excess ultrasonography, and Doppler of the left ventricular outflow track to estimate stroke volume. We briefly introduce other minimally invasive hemodynamic monitoring technologies before concluding that additional prospective data are urgently needed to adapt these technologies to the specific task of fluid removal by RRT and to learn how best to integrate them into practical fluid-management strategies. Second, we focus on the growth of novel extracorporeal blood purification devices, starting with brief reviews of the inflammatory underpinnings of multiorgan dysfunction and the specific applications of pathogen, endotoxin, and/or cytokine removal and immunomodulation. Finally, we review a series of specific adsorptive technologies, several of which have seen substantial clinical use during the COVID-19 pandemic, describing their mechanisms of target removal, the limited existing data supporting their efficacy, ongoing and future studies, and the need for additional prospective trials.

Venous Doppler to Assess Congestion: A Comprehensive Review of Current Evidence and Nomenclature

Organ congestion from venous hypertension is an important pathophysiological mechanism mediating organ injury in several clinical contexts including critical illness, congestive heart failure and end-stage chronic kidney disease. However, the practical evaluation of venous congestion is often challenging at the bedside because of the limitations of traditional methods. Point-of-care ultrasound (POCUS) enables the clinician to assess venous velocity profiles during the cardiac cycle using Doppler modalities. Venous Doppler profile abnormalities at multiple sites are detected when elevated venous pressure results in hemodynamic changes within the systemic venous circulation. The detection of these abnormal Doppler profiles may identify patients with clinically significant systemic venous congestion. These patients have been reported to be at increased risk of medical complications. Improving the evaluation of venous congestion may lead to individualized treatment and improved patient outcomes. In this review, we describe the physiologic principles necessary to understand venous Doppler assessment. We also propose a nomenclature for the description of venous Doppler profiles. Finally, we provide a narrative review of the current clinical evidence related to use of venous Doppler assessment in various clinical contexts.

Portal Hypertension in Nonalcoholic Fatty Liver Disease: From Pathogenesis to Clinical Practice

Portal hypertension in nonalcoholic fatty liver disease (NAFLD) mostly occur in cirrhotic stage. However, several experimental and clinical studies showed evidence of portal hypertension in NAFLD without significant or advance fibrosis. This early development of portal hypertension in NAFLD is associated with liver sinusoidal contraction by hepatocellular lipid accumulation and ballooning, which is also accompanied by capillarization and dysfunction of liver sinusoidal endothelial cells. Both of these impaired mechanical and molecular components can cause an increase in intrahepatic vascular resistance which lead to the increase of portal pressure in the absence of significant liver fibrosis. Extrahepatic factors such as insulin resistance and gut dysbiosis may also contribute to liver sinusoidal endothelial dysfunction and early portal hypertension in NAFLD. The clinical impact of early portal hypertension in NAFLD is still unclear. However, clinical tools for diagnosis and monitoring of portal hypertension in NAFLD are being investigated to predict high-risk patients and to guide therapy.

Pulsatile flow in venous perforators of the lower limb

Teaching traditionally asserts that the arterial pressure pulse is dampened across the capillary bed to the extent that pulsatility is non-existent in the venous circulation of the lower limbs. Herein, we present evidence of transmission of arterial pulsations across the capillary network into perforator veins in the lower limbs of healthy, heat-stressed humans. Perforator veins are connections from the superficial veins that drain into the deep veins. When assessed using ultrasound at rest, they infrequently demonstrate flow and a pulsatile flow waveform is not described. We investigated perforator vein pulsatility in ten young, healthy volunteers who underwent passive heating by +2 ºC deep body temperature via a hot-water-perfused suit, and five who also underwent active heating by +2 ºC via low-intensity cycling while wearing the hot-water-perfused suit. At +0.5 ºC increments in temperature, blood velocity in an ankle perforator vein was measured using duplex ultrasound. In all perforators with heating, sustained flow was demonstrated, with a pulsatile waveform that was synchronous with the cardiac cycle. The maximum velocity was 29 ± 14 cm/s with passive heating and approximately half with active heating (P=0.04). The small veins of the skin at the ankle also demonstrated increased perfusion with pulsatility, seen with low-velocity microvascular imaging technology. We consider explanations for this pulsatility and conclude that it is propagated from the arterial inflow through the skin microcirculation as a result of increased dilatation and flow volume, and that this a normal response to increased skin blood flow.

Usefulness of Serial Multiorgan Point-of-Care Ultrasound in Acute Heart Failure: Results from a Prospective Observational Cohort

Background and Objectives: Acute heart failure (AHF) is a common disease and a cause of high morbidity and mortality, constituting a major health problem. The main purpose of this study was to determine the impact of multiorgan ultrasound in identifying pulmonary hypertension (PH), a major prognostic factor in patients admitted due to AHF, and assess whether there are significant changes in the venous excess ultrasonography (VE × US) score or femoral vein Doppler at discharge. Materials and Methods: Patients were evaluated with a standard protocol of lung ultrasound, echocardiography, inferior vena cava (IVC) and hepatic, portal, intra-renal and femoral vein Doppler flow patterns at admission and on the day of discharge. Results: Thirty patients were enrolled during November 2021. The mean age was seventy-nine years (Standard Deviation-SD 13.4). Seven patients (23.3%) had a worsening renal function during hospitalization. Regarding ultrasound findings, VE × US score was calculated at admission and at discharge, unexpectedly remaining unchanged or even worsened (21 patients, 70.0%). The area under the curve for the lung score was 83.9% (p = 0.008), obtaining a cutoff value of 10 that showed a sensitivity of 82.6% and a specificity of 71.4% in the identification of intermediate and high PH. It was possible to monitor significant changes between both exams on the lung score (16.5 vs. 9.3; p < 0.001), improvement in the hepatic vein Doppler pattern (2.4 vs. 2.1; p = 0.002), improvement in portal vein Doppler pattern (1.7 vs. 1.4; p = 0.023), without significant changes in the intra-renal vein Doppler pattern (1.70 vs. 1.57; p = 0.293), VE × US score (1.3 vs. 1.1; p = 0.501), femoral vein Doppler pattern (2.4 vs. 2.1; p = 0.161) and IVC collapsibility (2.0 vs. 2.1; p = 0.420). Conclusions: Our study results suggest that performing serial multiorgan Point-of-Care ultrasound can help us to better identify high and intermediate probability of PH patients with AHF. Currently proposed multi-organ, venous Doppler scanning protocols, such as the VE × US score, should be further studied before expanding its use in AHF patients.

NAFLD mark: an accurate model based on microRNA-34 for diagnosis of non-alcoholic fatty liver disease patients

BACKGROUND

It remains essential for non-alcoholic fatty liver (NAFLD) patients, to develop a sensitive and specific diagnostic model. Data regarding the use of micro (mi)RNA-34 for NAFLD diagnosis are few. Routine clinical assessment, laboratory tests were done for Egyptian individuals (n = 314) were included (100 healthy individuals and 214 NAFLD patients). Quantification of miRNA-34 was done using real-time PCR. Extremely significant variables were entered into stepwise logistic regression. The diagnostic power of variables was estimated by the area under the ROC (AUC).

RESULTS

MiRNA-34 levels were higher in NAFLD patients than healthy individuals with a significant difference (P< 0.0001). The multivariate analysis was used to evaluate the NAFLD-associated variables (CRP, cholesterol, body mass index (BMI), ALT had p< 0.0001 while mRNA-34 had (p=0.0004). The AUCs (CI) of candidate NAFLD markers were in the order of miRNA-34 0.72 (0.66-0.77) < ALT 0.73 (0.67-0.79) < BMI 0.81 (0.76-0.86) < cholesterol < 0.85 (0.79-0.90) < CRP 0.88 (0.84-0.92). We developed a novel index for discriminating patients with NAFLD named NAFLD Mark. AUC was jumped to 0.98 (0.93-0.99) when five markers were combined. The AUC of NAFLD mark for NAFLD detection was higher than the AUCs of seven common NAFLD indexes (0.44-0.86).

CONCLUSIONS

The NAFLD mark is a non-invasive and highly sensitive and specific model for NAFLD diagnosis.

Comprehensive Assessment of Fluid Status by Point-of-Care Ultrasonography

The management of complex fluid and electrolyte disorders is central to the practice of nephrologists. The sensitivity of physical examination alone to determine fluid status is limited, precluding accurate clinical decision making. Point-of-care ultrasonography (POCUS) is emerging as a valuable, noninvasive, bedside diagnostic tool for objective evaluation of physiologic and hemodynamic parameters related to fluid status, tolerance, and responsiveness. Rapid bedside sonographic evaluation can obtain qualitative data on cardiac function and quantitative data on pulmonary congestion. Advanced POCUS, including goal-directed Doppler echocardiography, provides additional quantitative information, including flow velocities and pressures across the cardiac structures. Recently, abnormal Doppler flow patterns in abdominal organs secondary to increased right atrial pressure have been linked to congestive organ damage, adding another component to the hemodynamic assessment. Integrating POCUS findings with clinical and laboratory data can further elucidate a patient's hemodynamic status. This drives decisions regarding crystalloid administration or, conversely, diuresis or ultrafiltration and allows tailored therapy for individual patients. In this article, we provide an overview of the focused assessment of cardiovascular function and pulmonary and venous congestion using POCUS and review relevant literature.

Comprehensive Assessment of Fluid Status by Point-of-Care Ultrasonography

The management of complex fluid and electrolyte disorders is central to the practice of nephrologists. The sensitivity of physical examination alone to determine fluid status is limited, precluding accurate clinical decision making. Point-of-care ultrasonography (POCUS) is emerging as a valuable, noninvasive, bedside diagnostic tool for objective evaluation of physiologic and hemodynamic parameters related to fluid status, tolerance, and responsiveness. Rapid bedside sonographic evaluation can obtain qualitative data on cardiac function and quantitative data on pulmonary congestion. Advanced POCUS, including goal-directed Doppler echocardiography, provides additional quantitative information, including flow velocities and pressures across the cardiac structures. Recently, abnormal Doppler flow patterns in abdominal organs secondary to increased right atrial pressure have been linked to congestive organ damage, adding another component to the hemodynamic assessment. Integrating POCUS findings with clinical and laboratory data can further elucidate a patient's hemodynamic status. This drives decisions regarding crystalloid administration or, conversely, diuresis or ultrafiltration and allows tailored therapy for individual patients. In this article, we provide an overview of the focused assessment of cardiovascular function and pulmonary and venous congestion using POCUS and review relevant literature.

Adiponectin involved in portal flow hepatic extraction of 13C-methacetin in obesity and non-alcoholic fatty liver

Obesity and non-alcoholic fatty liver disease (NAFLD) are high prevalence, inter-related conditions at increased risk for advanced liver diseases and related mortality. Adiponectin and leptin have divergent roles in the pathogenesis of fat accumulation and NAFLD. However, the relationships between body and liver fat accumulation, early modification of liver function and unbalanced adipokine levels are still scarcely explored. We studied by (13C)-methacetin breath test ((13C)-MBT) 67 adults stratified according to body mass index, and to presence/absence of ultrasonographic nonalcoholic fatty liver disease (uNAFLD). uNAFLD was detected in 20%, 73% and 96% of normal weight, overweight and obese subjects, respectively. The delta over baseline after 15 min (DOB₁₅), a marker of hepatic extraction efficiency from portal blood flow, was lower in obese than in normal weight subjects, and in subjects with-, as compared to those without uNAFLD. The cumulative percent dose recovery after 30 min (cPDR₃₀), a marker of liver microsomal function, was lower in uNAFLD patients. DOB₁₅ was positively correlated with adiponectin levels in obese and in uNAFLD patients. uNAFLD patients also showed a positive correlation between cPDR₃₀ values and adiponectin. Our data indicate the existence of early alterations of liver function in obese and in patients with uNAFLD. These dysfunctions are linked to altered leptin/adiponectin balance and can be identified noninvasively by (13C)-MBT.

Clinical applications of the venous excess ultrasound (VExUS) score: conceptual review and case series

The importance of functional right ventricular failure and resultant splanchnic venous congestion has long been under-appreciated and is difficult to assess by traditional physical examination and standard diagnostic imaging. The recent development of the venous excess ultrasound score (VExUS) and growth of point-of-care ultrasound in the last decade has made for a potentially very useful clinical tool. We review the rationale for its use in several pathologies and illustrate with several clinical cases where VExUS was pivotal in clinical management.

VExUS Nexus: Bedside Assessment of Venous Congestion

Organ dysfunction in the setting of heart failure is mainly determined by backward transmission of increased right atrial pressure. Although traditional point-of-care ultrasound applications such as inferior vena cava and lung ultrasound have been increasingly incorporated in the clinical care of congestive heart failure, they do not directly evaluate the hemodynamic consequences of high right atrial pressure on organ blood flow. Congestion induces alterations in the venous flow patterns of abdominal organs that can be readily assessed using Doppler imaging. These alterations have been consistently associated with congestive organ dysfunction and adverse clinical outcomes. In this article, we provide a comprehensive overview of the bedside assessment of venous congestion using Doppler imaging. The review focuses mainly on the normal and abnormal Doppler patterns of the hepatic, portal, and intrarenal veins along with clinical examples of how to incorporate this tool in the management of patients with venous congestion.

US Elastography in Hepatic Fibrosis-Radiology In Training

A 72-year-old woman with an elevated body mass index and moderate alcohol intake was seen in the gastroenterology clinic. The patient had a past history of abnormal liver function tests and previous biopsy-proven steatosis with early fibrosis. She was reevaluated, following an initial loss to follow-up, by using US elastography to assess for fibrosis progression. The utility of US elastography in the noninvasive diagnosis and longitudinal monitoring of hepatic fibrosis is discussed. An overview of available technologies, including transient elastography and shear-wave elastography, is provided. ^©RSNA, 2021 Online supplemental material is available for this article.