Doppler study of hepatic vein in cirrhotic patients: Correlation with liver dysfunction and hepatic hemodynamics

[Ultrasound diagnostics of the liver : Principles and important pathologies]

Diffuse changes in the liver parenchyma, focal lesions and blood flow in hepatic vessels can be assessed using ultrasound. Screening by ultrasound can be used to detect hepatocellular carcinomas as possible malignant sequelae of liver cirrhosis. As metastases are far more frequent than primary malignant liver tumors, secondary malignant neoplasms should be taken into consideration as a differential diagnosis in the presence of focal liver lesions. This particularly concerns patients with a known metastatic disease. Benign focal liver lesions are often incidentally discovered in women of childbearing age. Cysts, hemangiomas and focal nodular hyperplasia mostly show typical morphological features in ultrasound and do not require further follow-up; however, with hepatic adenomas, regular follow-up is recommended due to the risk of bleeding and/or malignant transformation.

Hepatic perfusion as a new predictor of prognosis and mortality in critical care patients with acute-on-chronic liver failure

Background and aims

Liver diseases are frequent causes of morbidity and mortality worldwide. Liver diseases can lead to cirrhosis, with the risk of acute-on-chronic liver failure (ACLF). For the detection of changes in hepatic hemodynamics, Doppler ultrasonography is a well-established method. We investigated hepatic hemodynamics via serial Doppler ultrasonography to determine the predictive value of changes in hepatic perfusion for the outcome in patients with severe liver diseases compared to established prognostic models such as the MELD (Model for End-Stage Liver Disease) or CLIF-C (Chronic Liver Failure-Consortium) ACLF score.

Methods

In this prospective cohort study, hepatic perfusion was quantified at baseline before the initiation of treatment and every third day by means of serial measurements of the hepatic artery resistance index (HARI) and the maximum portal vein velocity (PVv) using Doppler ultrasonography in 50 consecutive patients with severe liver diseases admitted to a medical intensive care unit (MICU). The recorded hemodynamic parameters were compared to the MELD score, and the CLIF-C ACLF score to analyze their utility for the prediction of the outcome of patients with severe liver diseases, liver cirrhosis, and ACLF.

Results

The changes (delta) obtained by serial measurements of the MELD score, HARI, and PVv were analyzed through scatter plots. Bivariate correlation analysis yielded a new positive linear correlation between the delta-HARI and the delta-MELD score (r = 0.469; p < 0.001). In addition, our data revealed a new negative linear correlation between delta-PVv and the delta-MELD score (r = −0.279, p = 0.001). The leading cause of MICU mortality was acute-on-chronic liver failure (ACLF). A subgroup analysis of patients with liver cirrhosis revealed a positive linear correlation between the delta-HARI and the delta-CLIF-C-ACLF score (r = 0.252, p = 0.005). Of clinical relevance, non-survivors of ACLF exhibited a significantly higher mean value for the delta-HARI (0.010 vs. −0.005; p = 0.015) and a lower mean value for the delta-PVv (−0.7 vs. 1.9 cm/s; p = 0.037) in comparison to survivors of ACLF.

Conclusion

This study shows the prognostic value of the assessment of hepatic perfusion in critical care patients with severe liver diseases by bedside Doppler ultrasound examination and its utility as an accurate predictor of the outcome in patients with ACLF. Increasing HARI and a decreasing PVv are predictors of an adverse outcome. Delta-HARI and delta-PVv are new biomarkers of prognosis and ACLF-related mortality in patients with liver diseases. Delta-HARI and delta-PVv may be helpful in guiding clinical decision-making, especially in catecholamine and fluid management.

Hepatic function predictive value of hepatic venous waveform versus portal vein velocity in liver cirrhosis

Background:

This study assessed the hepatic vein waveform (HVW) and mean maximum portal vein velocity (MM-PVV) on Doppler ultrasound in patients with liver cirrhosis (LC) and compared it with that of age and sex-matched controls. It correlated the degree of HVW abnormality and MM-PVV changes with liver function based on Child-Turcotte-Pugh (CTP) to determine which was more predictive of CTP.

Methods:

Sixty patients with LC and 60 healthy controls were consecutively recruited into this study. Each patient was classed based on the CTP system after relevant tests. Doppler evaluation of the hepatic vein (HV) and MM-PVV were performed. HVW obtained was classified either into triphasic, biphasic, or monophasic.

Results:

Sixty cirrhotic and 60 age-matched control subjects aged 19–69 and 18–69 years, respectively, completed this study. All control subjects had a normal HVW pattern while 46 (76.7%) cirrhotic subjects had abnormal HVW (P < 0.001). The MM-PVV was significantly lower in cirrhotic subjects than in controls; 22.8 cm/s versus 33.6 cm/s (P < 0.001). The degree of HVW abnormality among cirrhotics showed a significant positive correlation with CTP (r = 0.283, P = 0.029). MM-PVV on the other hand showed no correlation with CTP class (r = −0.124; P = 0.346). Linear regression showed that HVW was a significant predictor of hepatic dysfunction based on CTP.

Conclusion:

Changes in the waveform pattern of the HVs are a good predictor of the derangement of hepatic function in patients with LC than changes in PVV. HVW pattern could therefore serve as an adjunct to CTP class in hepatic function assessment.

What is the difference in ablation zone of multi-bipolar radiofrequency ablation between liver cirrhosis and normal liver background? - a prospective clinical study

PURPOSE

To explore the differences in ablation zone between liver cirrhosis and normal liver background and investigate the effect of hepatic blood flow on ablation zone of RFA.

METHODS

Between 2017 and 2019, 203 patients who had liver malignancies and underwent percutaneous RFA with Celon bipolar electrodes enrolled into this study. There were 90 patients had liver cirrhosis and 113 patients had normal liver background. They were 63 females and 140 males with average age of 59.0 ± 10.9 years old. Contrast-enhanced CT/MRI was used to evaluate the ablation zone in one month after RFA. The hepatic flow measurements on CDFI and CEUS were performed before RFA. Correlations between ablation zone versus hepatic flow were assessed using multiple linear regression analysis.

RESULTS

The average ablation zone in cirrhotic liver was significantly larger than those in normal liver background with 3 cm tip of RF electrodes (length 3.5 ± 0.5 vs 3.1 ± 0.4 cm, p = 0.001; width 2.6 ± 0.3 vs 2.2 ± 0.3 cm, p < 0.001; thickness 2.5 ± 0.3 vs 2.0 ± 0.2 cm, p < 0.001). The similar result was found with three 4 cm tip of RF electrodes (width 3.6 ± 0.5 vs 3.1 ± 0.5 cm, p = 0.019; thickness 3.3 ± 0.5 vs 2.7 ± 0.5 cm, p = 0.002). The multiple linear regression analysis showed arrive time of hepatic vein and portal vein was statistically associated with ablation zone with 3 cm electrodes (p < 0.001, p = 0.001), but explained part of the variance (Adjusted R²=0.294, adjusted R²=0.212).

CONCLUSION

The ablation zones of RFA with multi-bipolar electrodes in liver cirrhosis were significantly larger than those in normal liver background, being up to 6 mm in thickness. The hepatic flow parameters partly contributed to the ablation zone.

Diagnostic accuracy of the attenuation value in abdominal contrast enhanced dynamic multi-detector-row computed tomography for esophageal varices in patients with liver cirrhosis

Purpose

To investigate whether the attenuation value obtained by subtracting the CT value obtained from abdominal dynamic contrast enhanced (ADCE)-MDCT imaging of the equilibrium phase from the value obtained from that of the portal phase in hepatic parenchyma is useful in distinguishing normal liver from liver cirrhosis (LC) and to predict the development of esophageal varices (EVs) in patients with LC.

Materials and methods

We assigned 72 outpatients to group A (n = 45; normal liver) and group B (n = 27; LC), who underwent ADCE-MDCT. The attenuation value and CT value of the hepatic parenchymal portal and equilibrium phase were compared, and the correlation between attenuation value and biomarkers (ALB, T-bil, PLT, FIB-4, APRI, and AAR) was investigated. Furthermore, we investigated differences in the attenuation value, FIB-4, APRI, and AAR between the two subgroups of group B [without EVs (group a) and with EVs (group b)]. We performed receiver operating characteristic (ROC) analysis of the attenuation value, FIB-4, APRI, and, AAR for subgroup a vs b and evaluated the diagnostic accuracy.

Results

Significant differences were observed between groups A and B in all items. The attenuation value correlated with ALB, T-bil, PLT, FIB-4, and APRI. Only attenuation value showed a significant difference between groups a and b. The best cut-off attenuation value, FIB-4, APRI, and AAR for predicting EVs, according to ROC analysis was 13.4 HU, 6.8, 1.9, and 1.5.

Conclusions

Attenuation value can be useful to quantitatively classify normal liver and LC and to predict EVs in patients with LC.

Ultrasonography for Noninvasive Assessment of Portal Hypertension

Portal hypertension is a major pathophysiology in patients with cirrhosis. Portal pressure is the gold standard to evaluate the severity of portal hypertension, and radiological intervention is the only procedure for pressure measurement. Ultrasound (US) is a simple and noninvasive imaging modality available worldwide. B-mode imaging allows broad applications for patients to detect and characterize chronic liver diseases and focal hepatic lesions. The Doppler technique offers real-time observation of blood flow with qualitative and quantitative assessments, and the application of microbubble-based contrast agents has improved the detectability of peripheral blood flow. In addition, elastography for the liver and spleen covers a wider field beyond the original purpose of fibrosis assessment. These developments enhance the practical use of US in the evaluation of portal hemodynamic abnormalities. This article reviews the recent progress of US in the assessment of portal hypertension.

Pre-operative Hepatic Artery Resistive Index is a Non-invasive Predictive Indicator of Prognosis in Biliary Atresia

AIMS

The aim of this study is to evaluate hepatic artery resistive index (HARI) as a noninvasive prognostic predictor by correlating it with peripheral blood nitric oxide (NO) levels, portal pressure (PP) and histopathological changes in the liver in patients of biliary atresia (BA).

MATERIALS AND METHODS

Twenty-five patients were included in the study prospectively from November 2012 to June 2014. All patients underwent Doppler sonography to calculate the HARI preoperatively. Peripheral blood NO was also measured preoperatively. Biochemical liver function tests (LFTs) were measured preoperatively and at 1, 3, and 6 months postoperatively. The PP was measured intraoperatively, and a liver biopsy was taken in all patients. Disappearance of jaundice defined successful surgical treatment. Postoperatively, a hepatobiliary IminoDiacetic Acid scan (HIDA) was done to demonstrate a patent bilio-enteric pathway.

RESULTS

The mean preoperative HARI was 0.78 ± 0.105, and the median was 0.80 (range 0.60-1.0). The median HARI was used to correlate the other parameters; 13 (52%) patients had HARI ≥0.8. The mean PP was 24.96 ± 6.54 mmHg. The HARI had a strong correlation with PP (P = 0.0001) and (NO) (P = 0.0001); with every 0.1 increase in HARI, there was 5.2 mmHg increase in PP and 3.8 μmol/L increase in NO. The histological parameters which reached significance in relation to HARI were hepatocellular damage, bile duct inflammation, portal inflammation, and portal fibrosis. The postoperative improvement in LFT was significantly better in patients with HARI <0.8. All four patients who died during or after the study period had HARI >0.8, elevated PP, and NO levels.

CONCLUSIONS

Preoperative HARI was found to have a direct correlation with PP and peripheral blood NO as a measure of portal hypertension. A preoperative HARI ≥0.8 should be considered as a risk factor for poor outcomes in BA.

A sonographic Doppler study of the hepatic vein, portal vein and hepatic artery in liver cirrhosis: Correlation of hepatic hemodynamics with clinical Child Pugh score in Singapore

Objective

Liver cirrhosis has been a rising complication of chronic liver disease in Singapore. Ultrasound has been widely accepted as a non-invasive imaging modality for the evaluation of hepatic haemodynamics. This study aims to correlate the Doppler ultrasound values with the progression of liver cirrhosis to allow further understanding and possible prediction of clinical events for timely intervention.

Methods

Study sample of 56 eligible patients with liver cirrhosis was divided according to their Child-Pugh clinical score into Child's A (n = 29 patients), B (n = 19 patients) and C (n = 8 patients). The maximum portal vein velocity, maximum hepatic vein velocity, maximum hepatic artery velocity and hepatic artery resistive index were assessed by Doppler ultrasound.

Results

The incidence of ascites increases with the severity of cirrhosis. Flattening of the hepatic vein waveforms was dependant on degree of liver cirrhosis. Maximum hepatic vein velocity was higher in cirrhotic patients (where p = 0.05). Maximum portal vein velocity was found to be lower in cirrhosis (where p < 0.001) and mean maximum portal vein velocity decreases as severity of cirrhosis worsens. Hepatic artery resistive index was significantly higher in cirrhosis (where p < 0.001). Significant association was found between maximum hepatic vein velocity and maximum hepatic artery velocity and significant negative correlation was observed with the maximum portal vein velocity and hepatic artery resistive index.

Conclusion

The study demonstrated that these parameters can supplement the evaluation of liver cirrhosis and will be able to distinguish the different grades of liver cirrhosis using Doppler ultrasound.

Gender Linked Metric Analysis of Portal Vein: A Sonographic Appraisal

INTRODUCTION

Portal hypertension is one of the most mystifying and disconcerting abdominal ailment. Ultrasonography (USG) is an effective diagnostic tool for its prompt management. Knowledge of normal calibre of portal vein in a local setting is essential as literature reports contrasting values in different regions. It helps in early diagnosis of portal hypertension even before it is clinically manifested thereby assisting clinicians and interventional radiologists in pertinent management.

AIM

Study was aimed to evaluate the Portal Vein Diameter (PVD) and find its correlation with gender by using USG in North Indian population.

MATERIALS AND METHODS

A total of 300 healthy adults were included in the study. Portal vein diameter was measured in supine position and normal respiration by grey scale USG. The portal vein diameter was correlated with age and gender statistically using independent Student's t-test and ANOVA.

RESULTS

Mean PVD of (9.49±1.03 mm) was observed in the present cross-sectional study. Male showed a significantly higher mean PVD (9.70±1.02 mm) as compared to females (9.10±0.94 mm).

CONCLUSION

Scarcity of information concerning ultrasonographically measured standard portal vein diameter and inconstant values reported in literature necessitates the need for establishing local standard value. In the given subset of population the portal vein diameter was influenced by the gender. The information will be helpful in prompt diagnosis and management of portal hypertension.

Hepatic Venous Waveform, Splenoportal and Damping Index in Liver Cirrhosis: Correlation with Child Pugh's Score and Oesophageal Varices

INTRODUCTION

Clinical assessment of chronic liver disease is done by Modified Child Pugh's and Model for end-stage liver disease scoring system. Measurement of hepatic venous pressure gradient (HVPG) and Upper GI Endoscopy are considered the gold standards for measurement of portal hypertension in cirrhotics. There is a need for non-invasive evaluation of portal hypertension. Ultrasonography with colour and spectral Doppler evaluation may be an effective, rapid and inexpensive alternative.

AIM

To evaluate hepatic venous waveform, damping index, splenoportal index in patients of cirrhosis on Colour Doppler ultrasound, also predict severity of portal hypertension and presence of oesophageal varices.

MATERIALS AND METHODS

Thirty patients of chronic liver disease were included in the study. Ultrasound and colour Doppler was done to look hepatic venous waveform pattern, Damping Index (DI), and Splenoportal Index (SPI). Contrast-enhanced Computed Tomography scan (CT) was done if renal function tests were normal, else endoscopy when the renal function tests were deranged to look for oesophageal varices.

RESULTS

Twenty two (73.3%) patients had monophasic waveform. Biphasic and triphasic waveforms were seen in 4 (13.3%) cases. Twenty two patients (73.3%) had monophasic waveforms and majority of them were in class C. This distribution of hepatic vein waveform was statistically significantly with the Child Pugh's class (p<0.05). Twenty patients (66.7%) had value of Damping index more than >0.6 where majority of patients (18) belonged to class C and 2 in class B. There was a positive correlation between Child Pugh's total score and Damping index (r=0.614; p<0.05). There was weak positive correlation between splenoportal index and Child Pugh's score (r=0.269; p=0.15).

CONCLUSION

Change in triphasic to monophasic waveform and DI >0.6 suggests severe liver dysfunction and is associated with severe portal hypertension. Hepatic venous waveform pressure changes, DI and SPI have no value in predicting presence of oesophageal varices.

Liver Stiffness: A Significant Relationship with the Waveform Pattern in the Hepatic Vein

The aim of this prospective study was to assess the relationship between liver stiffness and hepatic vein waveform patterns in 42 patients with chronic hepatitis and 55 with cirrhosis. Liver stiffness measurement (LSM) values (FibroScan, Echosens, Paris, France) were significantly lower in the triphasic pattern group (11.3 ± 8.4 kPa) than in the monophasic pattern (32.5 ± 23.5 kPa, p = 0.001) and biphasic pattern (25.6 ± 18.1 kPa, p = 0.001) groups, indicating no significant relationship with portal pressure. The ability to diagnose cirrhosis represented by the highest area under the receiver operating characteristic curve was 0.921 (83.6% sensitivity, 90.5% specificity, best cutoff value: 16.9 kPa) by LSM and 1.000 (best cutoff value: 19.4 kPa) by LSM combined with the monophasic pattern. This study revealed a close linkage between liver stiffness and hepatic vein waveform findings, resulting in a better understanding of hepatic vein hemodynamics and wider application of its analysis.

Arterial ammonia levels in cirrhosis are determined by systemic and hepatic hemodynamics, and by organ function: a quantitative modelling study

BACKGROUND & AIMS

Hyperammonaemia is a common complication of chronic liver failure. Two main factors are thought to underlie this complication: a loss of hepatic detoxification function and the development of portosystemic shunting. However, few studies have tried to quantify the importance of portosystemic shunting. Here, we used a theoretical approach to test the hypothesis that the development of portosystemic shunting is sufficient to cause hyperammonaemia in cirrhosis.

METHODS

Two mathematical models are developed. The first one describes the main vascular resistances of the circulation and is used to provide scenarios for the distributions of organ blood flow in cirrhosis, which are necessary to run the second model. The second model predicts arterial ammonia levels resulting from ammonia metabolism in gut, liver, kidney, muscle and brain, and the distribution of organ blood flow.

RESULTS

The fraction of gastrointestinal blood flow shunted through collaterals was estimated to be 41% in mild cirrhosis, 69% in moderate and 85% in severe cases. In the second model, the redistribution of organ blood flow associated with severe cirrhosis was sufficient to cause hyperammonaemia, even when the hepatic detoxification function and the ammonia production were set to normal.

CONCLUSIONS

The model indicates that the development of portosystemic shunting in cirrhosis is sufficient to cause hyperammonaemia. Interventions that reduce the fraction of shunting may be future targets of therapy to control severity of hyperammonaemia.

Validation and Calibration of an Electrical Analog Model of Human Liver Perfusion Based on Hypothermic Machine Perfusion Experiments

Purpose

Hypothermic machine perfusion (HMP) is reviving as a better preservation method for donor livers than the golden standard of cold storage, but still faces challenges such as the risk for endothelial damage and flow competition between the arterial and portal venous inflow. Therefore, we previously developed an electrical analog model to investigate the effect of HMP settings on the human liver hemodynamics. While the model provided plausible results, it is based on a number of assumptions and its performance was never subjected to experimental validation. To this end, we present a new methodology to validate and calibrate this model to a specific liver.

Methods and Results

HMP experiments were performed to capture the perfusion behavior of a human liver during varying perfusion settings. Simultaneous pressure and flow signals were acquired at the hepatic artery, portal vein, and vena cava inferior. The calculation of hydraulic input impedances enabled reduced Windkessel models to be fitted to the global hepatic perfusion properties as an intermediate step. Based on these Windkessel models, the extended electrical analog model was calibrated to the specific available liver. Results revealed that literature values of one of the critical model parameters (wall viscoelasticity) are a few orders of magnitude off, having important consequences for simulated (pulsatile) hemodynamic variables.

Conclusions

A novel methodology, based on HMP experiments, signal processing and unconstrained nonlinear optimization was developed to validate and calibrate the liver-specific extended electrical model. Future research may focus on extending this approach to other applications (e.g. liver pathologies such as cirrhosis).

Hepatic vein waveforms in liver cirrhosis re-evaluated

OBJECTIVE

There are many studies on changes in Doppler waveforms of hepatic veins in cirrhotic liver. It is postulated that dampening of phasic oscillations appears with worsening of liver function. Our aim was to reevaluate the significance of Doppler waveforms of hepatic vein in cirrhotic patients and to correlate with hepatic blood flow.

PATIENTS AND METHOD

One hundred and thirty-five consecutive patients of liver cirrhosis and 60 age and sex matched non-cirrhotic controls were enrolled in this study. Doppler waveforms were obtained from right hepatic vein during normal respiration. Other parameters measured were flow volume of portal trunk, right portal vein and proper hepatic artery.

RESULT

Waveforms of the hepatic vein were classified into triphasic, biphasic and flat patterns. Flat waveform was rare and appeared in only 3% cases. There was no correlation between liver dysfunction and patterns of waveforms. Inflow, particularly to the right lobe, was significantly elevated in cases associated with the non-triphasic waveforms.

CONCLUSION

This study shows that the flat waveforms have no diagnostic value. Role of hepatic blood flow seems to be important suggesting hemodynamic changes rather than liver dysfunction as a plausible cause of change in waveforms.

A semi-mechanistic model to predict the effects of liver cirrhosis on drug clearance

BACKGROUND AND OBJECTIVE

Liver cirrhosis is characterized by a decrease in functional hepatocytes, lowered circulating levels of plasma proteins and alterations in blood flow due to the development of portacaval shunts. Depending on the interplay between these parameters and the characteristics of an administered drug, varying degrees of impaired systemic clearance and first-pass metabolism are anticipated. The Simcyp Population-based ADME Simulator has already been used successfully to incorporate genetic, physiological and demographic attributes of certain subgroups within healthy populations into in vitro-in vivo extrapolation (IVIVE) of xenobiotic clearance. The objective of this study was to extend population models to predict systemic and oral drug clearance in relation to the severity of liver cirrhosis.

METHODS

Information on demographics, changes in hepatic blood flow, cytochrome P450 enzymes, liver size, plasma protein binding and renal function was incorporated into three separate population libraries. The latter corresponded to Child-Pugh scores A (mild), B (moderate) and C (severe) liver cirrhosis. These libraries, together with mechanistic IVIVE within the Simcyp Simulator, were used to predict the clearance of intravenous and oral midazolam, oral caffeine, intravenous and oral theophylline, intravenous and oral metoprolol, oral nifedipine, oral quinidine, oral diclofenac, oral sildenafil, and intravenous and oral omeprazole. The simulated patients matched the clinical studies as closely as possible with regard to demographics and Child-Pugh scores. Predicted clearance values in both healthy control and liver cirrhosis populations were compared with observed values, as were the fold increases in clearance values between these populations.

RESULTS

There was good agreement (lack of statistically significant difference, two-tailed paired t-test) between observed and predicted clearance ratios, with the exception of those for two studies of intravenous omeprazole. Predicted clearance ratios were within 0.8- to 1.25-fold of observed ratios in 65% of cases (range 0.34- to 2.5-fold).

CONCLUSION

The various drugs that were studied showed different changes in clearance in relation to disease severity, and a 'one size fits all' solution does not exist without considering the multiple sources of the changes. Predictions of the effects of liver cirrhosis on drug clearance are of potential value in the design of clinical studies during drug development and, clinically, in the assessment of likely dosage adjustment.

Flat panel computed tomography for non-invasive flow measurement: initial results in in-vitro studies

The purpose was to evaluate the feasibility of flat panel computed tomography (FPCT) for quantifying flow by analyzing contrast changes along the z-axis in an in-vitro setting. Contrast material was injected in a 3-mm silicone tube at flow rates of 0.1, 0.2, 0.5 and 1.0 ml/s using a commercially available injector pump. FPCT scans of this phantom were performed with a gantry rotation time of 3 s. From this data 41 phases were reconstructed at different points in time using a full and a partial gantry rotation. The differences in the contrast material arrival time and the contrast enhancement along the z-axis were recorded. Flow was calculated from this data and compared to the injector settings. There was a good agreement between the injector settings and the calculated flow rates, but agreement decreased with increasing flow rates. Absolute (percent) mean deviation between the injector settings and calculated flow values was 0.0230 +/- 0.0489ml/s (3.7243 +/- 4.7817%) using the full gantry rotation. Repeated-measurement ANOVA failed to show significant differences between the various techniques (p = 0.9726). FPCT allows for computing flow. While preliminary results indicate a good agreement at low flow rates, further studies are needed to assess this technique for higher flow rates.