EUS-guided portal vein catheterization: a promising novel approach for portal angiography and portal vein pressure measurements

Endoscopic ultrasound-guided portal pressure gradient measurement in managing portal hypertension

Portal hypertension (PH) is still a challenging clinical condition due to its silent manifestations in the early stage and needs to be measured accurately for early detection. Hepatic vein pressure gradient measurement has been considered as the gold standard measurement for PH; however, it needs special skill, experience, and high expertise. Recently, there has been an innovative development in using endoscopic ultrasound (EUS) for the diagnosis and management of liver diseases, including portal pressure measurement, which is commonly known as EUS-guided portal pressure gradient (EUS-PPG) measurement. EUS-PPG measurement can be performed concomitantly with EUS evaluation for deep esophageal varices, EUS-guided liver biopsy, and EUS-guided cyanoacrylate injection. However, there are still major issues, such as different etiologies of liver disease, procedural training, expertise, availability, and cost-effectiveness in several situations with regard to the standard management.

Endoscopic ultrasound-guided vascular interventions: An expanding paradigm

Endoscopic ultrasound (EUS) has expanded its arena from a mere diagnostic modality to an essential therapeutic tool in managing gastrointestinal (GI) diseases. The proximity of the GI tract to the vascular structures in the mediastinum and the abdomen has facilitated the growth of EUS in the field of vascular interventions. EUS provides important clinical and anatomical information related to the vessels' size, appearance and location. Its excellent spatial resolution, use of colour doppler with or without contrast enhancement and ability to provide images “real-time” helps in precision while intervening vascular structures. Additionally, structures such as venous collaterals or varices can be dealt with optimally using EUS. EUS-guided vascular therapy with coil and glue combination has revolutionized the management of portal hypertension. It also helps to avoid radiation exposure in addition to being minimally invasive. These advantages have led EUS to become an upcoming modality to complement traditional interventional radiology in the field of vascular interventions. EUS-guided portal vein (PV) access and therapy is a new kid on the block. EUS-guided portal pressure gradient measurement, injecting chemotherapy in PV and intrahepatic portosystemic shunt has expanded the horizons of endo-hepatology. Lastly, EUS has also forayed into cardiac interventions allowing pericardial fluid aspiration and tumour biopsy with experimental data on access to valvular apparatus. Herein, we provide a comprehensive review of the expanding paradigm of EUS-guided vascular interventions in GI bleeding, portal vein access and its related therapeutic interventions, cardiac access, and therapy. A synopsis of all the technical details involving each procedure and the available data has been tabulated, and the future trends in this area have been highlighted.

The Role of Endoscopic Ultrasound in Hepatology

Endoscopic ultrasound (EUS) has been an indispensable and widely used diagnostic tool in several medical fields, including gastroenterology, cardiology, and urology, due to its diverse therapeutic and diagnostic applications. Many studies show that it is effective and safe in patients with liver conditions where conventional endoscopy or cross-sectional imaging are inefficient or when surgical interventions pose high risks. In this article, we present a review of the current literature for the different diagnostic and therapeutic applications of EUS in liver diseases and their complications and discuss the potential future application of artificial intelligence analysis of EUS.

Endohepatology - current status

PURPOSE OF REVIEW

This article discusses the most recent studies regarding the emerging field of endohepatology - the use of diagnostic and therapeutic endoscopic tools for the management of patients with liver disease and portal hypertension.

RECENT FINDINGS

New research has shown that liver biopsy specimens obtained by each Endoscopic ultrasound (EUS)-guidance, the percutaneous approach, and the transjugular approach contained sufficient portal triads to adequately analyzed by experienced pathologists - suggesting that any of these routes of liver biopsy is clinically acceptable; further, all had similar rates of adverse events. An initial prospective study showed that EUS guided portal pressure measurement was safe, effective, and accurate. A recent metanalysis showed that EUS-guided cyanoacrylate injection and coil embolization was statistically more efficacious and with less complications than EUS guided cyanoacrylate injection and EUS guided coil injection alone, suggesting that combination therapy appears to be the preferred approach for gastric varices (GV) bleeding. A prospective study evaluating focal liver lesions showed that the use of artificial intelligence had up to 100% sensitivity and 81% specificity for identifying malignant focal liver lesions.

SUMMARY

EUS guided liver biopsy is safe and enables accurate diagnosis of underlying liver disease. EUS guided portal pressure measurement is also safe and is accurate. Combination therapy of EUS guided cyanoacrylate injection and coil embolization is more efficacious and has less complications than injection or coil therapy alone when used for GV bleeding. Artificial intelligence is highly sensitive and specific when used in conjunction with EUS in the diagnosis of malignant focal liver lesions. Endohepatology is a rapidly expanding field with great potential.

Endoscopic Ultrasound Evaluation of Portal Pressure

Portal hypertension is a complex syndrome with multiple clinical manifestations that develop in a variety of conditions and diseases. The spectrum of portal hypertension manifestations is wide and dependent on the physiologic site of increased portal resistance (pre-, post-, and sinusoidal or intrahepatic), as well as the presence of hepatocellular dysfunction.

Role of endoscopic ultrasound in the field of hepatology: Recent advances and future trends

The role of endoscopic ultrasound (EUS) as a diagnostic and therapeutic modality for the management of various gastrointestinal diseases has been expanding. The imaging or intervention for various liver diseases has primarily been the domain of radiologists. With the advances in EUS, the domain of endosonologists is rapidly expanding in the field of hepatology. The ability to combine endoscopy and sonography in one hybrid device is a unique property of EUS, together with the ability to bring its probe/transducer near the liver, the area of interest. Its excellent spatial resolution and ability to provide real-time images coupled with several enhancement techniques, such as contrast-enhanced (CE) EUS, have facilitated the growth of EUS. The concept of “Endo-hepatology” encompasses the wide range of diagnostic and therapeutic procedures that are now gradually becoming feasible for managing various liver diseases. Diagnostic advancements can enable a wide array of techniques from elastography and liver biopsy for liver parenchymal diseases, to CE-EUS for focal liver lesions to portal pressure measurements for managing various liver conditions. Similarly, therapeutic advancements range from EUS-guided eradication of varices, drainage of bilomas and abscesses to various EUS-guided modalities of liver tumor management. We provide a comprehensive review of all the different diagnostic and therapeutic EUS modalities available for the management of various liver diseases. A synopsis of all the technical details involving each procedure and the available data has been tabulated, and the future trends in this area have been highlighted.

The role of endoscopic ultrasound for portal hypertension in liver cirrhosis

Chronic liver disease is still a major problem because disease progression will ultimately lead to liver cirrhosis. Portal hypertension is the hallmark in advanced liver disease management. By establishing portal vein access, endoscopic ultrasound (EUS) has been utilized in various clinical applications. In comparison to standard upper gastrointestinal endoscopy, EUS-Doppler has been shown to be a better modality for detecting esophageal and gastric varices along with peri-esophageal collateral veins, para-esophageal collateral veins, and perforating veins, and may be used to objectively predict the recurrence of bleeding. EUS-guided portal vein catheterization has also been proposed to overcome the limitations of trans-jugular approaches. The combination of EUS-elastography and azygos vein evaluation can also enhance the diagnostic accuracy of each modality. Another well-known implementation of EUS-guided procedures is in the management of ascites; particularly in paracentesis and ascitic fluid analysis. In addition, the most common clinical application of EUS in the treatment of portal hypertension is through vascular therapy or creation of intrahepatic portosystemic shunts. Major drawbacks of EUS mainly revolve around technical difficulties, the high cost of the procedure, as well as the requirement of more studies in humans to evaluate EUS-guided advanced therapeutic modalities in portal hypertension.

Development of a Novel Endovascular Brachytherapy Stent: A Proof-of-concept Study

BACKGROUND AND AIMS

Endovascular implantation of iodine-125 (¹²⁵I) seeds strand combined with stent is an effective method of treatment for portal vein tumor thrombosis. The aim of this study was to develop a novel endovascular brachytherapy stent (EVB-Stent) and to evaluate its feasibility of use.

METHODS

An EVB-Stent was implanted into the main portal vein (MPV) in a live porcine model via the percutaneous transhepatic route. Blood samples were collected and tested before and after operation, as well as before euthanasia. Single-photon emission computed tomography (SPECT) combined with CT (SPECT/CT) scan were performed directly after operation and CT scan was performed 2 months after implantation. After the CT scan was performed, all animals were euthanized and histologically examined.

RESULTS

The novel stent was successfully positioned in all six pigs. No deterioration of liver function was observed during the 2-month follow-up period. SPECT/CT revealed the uniform distribution of radiation around the seeds strand, and the hottest spot was near the center of the MPV. The patency of the stented MPV was confirmed using CT scans. The tissue-accumulated absorbed dose was 31,822.11 mGy at 10 mm transversely away from the midpoint of the ¹²⁵I seeds strand, with a half-life of 59.4 days. Pathological examination results showed no significant atrophy or inflammation of adjunct liver tissue, and no obvious intima thickening or thrombosis were detected in the stented MPV.

CONCLUSIONS

A liver porcine model was used to demonstrate that the transhepatic placement of a novel endovascular brachytherapy stent, EVB-Stent, is both technically feasible and safe.

Endoscopic Ultrasound-Guided Vascular Procedures: A Review

Since the 1980s, endoscopic ultrasound has advanced from being purely diagnostic to an interventional modality. The gastrointestinal tract offers an exceptional window for assessing the vascular structures in the mediastinum and in the abdomen. This has led to a rapidly growing interest in endoscopic ultrasound-controlled vascular interventions as a minimally invasive alternative to surgical and radiological procedures.

Advances in Interventional Endoscopic Ultrasound (EUS): A Technical Review

Endoscopic ultrasound (EUS) has become the therapeutic intervention of choice for multiple diseases and continues to evolve rapidly. Its increasing use has allowed the development and adaptation of multiple, revolutionary devices and tools. Currently, there is paucity of randomized clinical trials evaluating multiple EUS-guided interventions and the vast majority of published data is heterogenous. However, the available literature on EUS-guided therapeutic interventions continues to expand and demonstrate its safety, efficacy and cost effectiveness in carefully selected patients when performed by expert endosonographers. The future of interventional EUS appears to be bright!

Application of CT-based radiomics in predicting portal pressure and patient outcome in portal hypertension

PURPOSE

Portal venous pressure (PVP) measurement is of clinical significance, especially in patients with portal hypertension. However, the invasive nature and associated complications limits its application. The aim of the study is to propose a noninvasive predictive model of PVP values based on CT-extracted radiomic features.

METHODS

Radiomics PVP (rPVP) models based on liver, spleen and combined features were established on an experimental cohort of 169 subjects. Radiomics features were extracted from each ROI and reduced via the LASSO regression to achieve an optimal predictive formula. A validation cohort of 62 patients treated for gastroesophageal varices (GOV) was used to confirm the utility of rPVP in predicting variceal recurrence. The association between rPVP and response to treatment was observed.

RESULTS

Three separate predictive formula for PVP were derived from radiomics features. rPVP was significantly correlated to patient response to endoscopic treatment for GOV. Among which, the model containing both liver and spleen features has the highest predictability of variceal recurrence, with an optimal cut-off value at 29.102 mmHg (AUC 0.866). A Kaplan Meier analysis further confirmed the difference between patients with varying rPVP values.

CONCLUSION

PVP values can be accurately predicted by a non-invasive, CT derived radiomics model. rPVP serves as a non-invasive and precise reference for predicting treatment outcome for GOV secondary to portal hypertension.

Endoscopic ultrasonography guided transgastric trans-portal system fine needle aspiration for diagnosing pancreatic head and uncinate process malignancy

Background

Endoscopic ultrasonography guided fine needle aspiration (EUS-FNA) is a well-established technique for diagnosing pancreatic malignancy. In general, tissue of pancreatic head and uncinate process lesions is obtained via a transduodenal approach. However, this tissue-acquisition modality is not applicable in cases of pyloric obstruction and duodenal bulb ulceration. The aim of this study is to determine the feasibility and safety of a novel EUS-guided transgastric trans-portal system FNA in the diagnosis of pancreatic head and uncinate process cancer.

Methods

This study retrospectively analyzed 26 consecutive inpatient patients who had undergone EUS-FNA for highly suspected malignancy of pancreatic head or uncinate process between December 2013 and December 2018. EUS-guided transgastric trans-portal vein (trans-PV, n=2) or trans-superior mesenteric vein (trans-SMV, n=24) FNA was performed in the patients under conscious sedation. Feasibility, diagnostic yield and complication rates of the technique were evaluated.

Results

Specimens obtained by EUS-guided transgastric trans-portal system FNA were adequate for cytological evaluation in all 26 patients. Cytological diagnosis of adenocarcinoma was established in 22 patients, while the remaining 4 patients were negative. The diagnostic accuracy, sensitivity and specificity were 92.3%, 91.7% and 100% respectively. No immediate or delayed procedure-related complications were observed.

Conclusions

EUS-guided transgastric trans-portal system FNA is a feasible and probably safe method for diagnosing pancreatic head and uncinate process malignancy. Careful selection of the potential candidates and close periprocedural observation are mandatory.

Endoscopic ultrasonography and small-bowel endoscopy: Present and future

Over the last decade, impressive technological advances have occurred in ultrasonography and small-bowel endoscopy. Nowadays, endoscopic ultrasonography is an essential diagnostic tool and a therapeutic weapon for pancreatobiliary disorders. Capsule endoscopy and device-assisted enteroscopy have quickly become the reference standard for the diagnosis of small-bowel luminal diseases, thereby leading to radical changes in diagnostic and therapeutic pathways. We herein provide an up-to-date overview of the latest advances in endoscopic ultrasonography and small-bowel endoscopy, focusing on the emerging paradigms and technological innovations that might improve clinical practice in the near future.

The role of EUS in diagnosis and treatment of liver disorders

Background and aim  Transabdominal ultrasound (US), computed tomographic scanning (CT) and magnetic resonance imaging (MRI) are established diagnostic tools for liver diseases. Percutaneous transhepatic cholangiography is used to perform hepatic interventional procedures including biopsy, biliary drainage procedures, and radiofrequency ablation. Despite their widespread use, these techniques have limitations. Endoscopic ultrasound (EUS), a tool that has proven useful for evaluating the mediastinum, esophagus, stomach, pancreas, and biliary tract, has an expanding role in the field of hepatology complementing the traditional investigational modalities. This review aimed to assess the current scientific evidence regarding diagnostic and therapeutic applications of EUS for hepatic diseases.

Insights into the role of endoscopic ultrasound-guided vascular therapy

Gastroesophageal variceal bleeding is a life-threatening complication in patients with liver cirrhosis and portal hypertension. The endoscopic injection of cyanoacrylate is considered as the first-line alternative for gastric varices treatment; however, the incidence of adverse events supports the endoscopic ultrasound–guided approach. Endoscopic ultrasound–guided interventions are a safe and feasible technique for the injection of sclerosants, cyanoacrylate, thrombin, and the deployment of coils into targeted vessels. This review article aims to offer an overview of the role of endoscopic ultrasound–guided vascular therapy and present the available data regarding endoscopic ultrasound–guided management of gastrointestinal bleeding and other vascular therapies. The available data have shown the superiority of endoscopic ultrasound–guided endovascular therapy over the endoscopic technique, which supports the implementation of endoscopic ultrasound–guided therapy in therapeutical algorithms and guidelines. Regarding whether injecting cyanoacrylate, the deployment of coils, or combined therapy, we recommend the endoscopic ultrasound–guided combined therapy in patients with gastric varices due to the high eradication rate with lower rebleeding and reintervention rates. Multicenter worldwide studies are required to confirm the actual clinical applicability of endoscopic ultrasound–guided endovascular therapy and establish treatment algorithms. Endoscopic ultrasound offered a safe and effective alternative in the management of variceal and nonvariceal gastrointestinal bleeding, with the implementation of new diagnostic and treatment options for various gastrointestinal conditions, representing a new territory for research and development.

Endoscopic Ultrasound-Guided Interventions for the Measurement and Treatment of Portal Hypertension

The number of endoscopic ultrasound (EUS)-guided interventions is rapidly growing within advanced endoscopy. EUS offers high-resolution imaging of mediastinal and intra-abdominal vasculature, which can be targeted for various interventions, hence a growing number of studies have explored EUS-guided vascular catheterization. Potential clinical applications of EUS-guided portal venous access include angiography, measurement of the portosystemic pressure gradient, and EUS-guided transhepatic intrahepatic portosystemic shunt creation. This article reviews different devices and techniques used in these applications.

Endoscopic Ultrasound-Guided Portal Pressure Measurement and Interventions

A growing number of studies have explored endoscopic ultrasound (EUS)-guided vascular catheterization. Potential clinical applications of EUS-guided portal venous access include angiography, measurement of the portosystemic pressure gradient, EUS-guided transhepatic intrahepatic portosystemic shunt creation and portal vein sampling for the evaluation in gastrointestinal cancer. The following article reviews the different devices and techniques employed in these applications.

Endoscopic Ultrasound-Guided Vascular Interventions: From Diagnosis to Treatment

The development of endoscopic ultrasound was driven by the need to develop less invasive alternatives to surgical and radiologic interventions for a wide variety of gastrointestinal conditions. During the past decade, there has been a very rapid growth in the clinical role and capabilities of endoscopic ultrasound-guided therapeutic interventions. Endoscopic ultrasound offers both real-time imaging and access to structures within and adjacent to the gastrointestinal tract. The proximity of the gastrointestinal system to vascular structures throughout the abdomen and the mediastinum allows for endoscopic ultrasound-guided vascular access and therapy. The recent development of endoscopic ultrasound-guided vascular interventions has relied both on finding new applications for standard endoscopic accessories and on commandeering tools originally developed for use in interventional radiology. This article provides a review of the literature regarding the current state of endoscopic ultrasound for the management of variceal and nonvariceal bleeding, portal vein angiography and pressure measurements, intrahepatic portosystemic shunts, endoscopic ultrasound-guided fine-needle aspiration for portal vein sampling, drug administration and embolization as well as endoscopic ultrasound-guided cardiac access and treatment.

EUS-guided portal pressure measurement (with videos)

A growing number of studies have explored EUS-guided vascular catheterization due to the relative proximity of the gastrointestinal tract to the major blood vessels of the mediastinum and abdomen. In particular, EUS-guided access of the portal vein (PV) may be favorable given the relative difficulty of PV access through standard percutaneous routes. Two major diagnostic applications of EUS-guided vascular access include angiography and assessment of intravascular pressure. This review will outline the different devices and techniques employed to obtain angiographic visualization and/or direct pressure measurements of the portal circulation. Ease of access, safety, and important lessons learned from each approach will be highlighted.

Endoscopic Ultrasound-guided Portal Venous Access: Diagnostic and Therapeutic Implications

Endoscopic ultrasound (EUS) has evolved from a purely diagnostic to an interventional modality offering minimally invasive alternatives to surgical and radiologic interventions. This has led to a rapidly growing interest in EUS-guided vascular interventions. EUS-guided portal venous access is an emerging technique which opens a new arena for interventional vascular EUS. Portal vein can be accessed under EUS guidance with high precision and low risk of complications thus expanding its application for both benign and malignant conditions. Potential applications of EUS-guided portal vein access include: fine needle aspiration of portal vein thrombus and portal venous blood sampling for circulating tumor cells for diagnosis and staging of occult and known malignancies; portal vein angiography, portal pressure measurement, and creation of endoscopic intrahepatic portosystemic shunt; portal vein embolization and targeted drug delivery. This article will review the current literature on EUS-guided portal vein access, its feasibility and safety in animal and human studies, and current diagnostic and therapeutic applications with future directions.

Interventional endoscopic ultrasonography: Where are we headed?

Endoscopic ultrasonography (EUS) is an essential endoscopic tool within the diagnostic and therapeutic armamentarium of gastrointestinal and hepatic diseases. EUS-guided tissue acquisition will develop towards facilitating personalized treatment by obtaining large representative tissue specimens for elaborate immunohistochemical and biomolecular typing of the tumor. Intratumoral or intravascular delivery of drugs potentially offers many advantages over systemic injection. Intratumoral application of radiofrequency ablation and photodynamic therapy show promise but need to be explored further. Appositioning and connecting luminal structures within the gastrointestinal tract using fully covered expandable lumen-apposing stents will expand its indication far beyond the drainage of (infected) fluid collections and EUS-guided gastrojejunostomy is a particularly exciting development that could have significant impact on the management of gastric outlet obstruction.

Endoscopic Ultrasound-Guided Direct Portal Pressure Measurement Using a Digital Pressure Wire with Real-Time Remote Display: A Survival Study

BACKGROUND

Portal hypertension is necessary for the development of most clinical complications of cirrhosis. We recently reported a novel, endoscopic ultrasound (EUS)-guided technique for direct portal pressure measurements using a digital pressure wire.

AIMS

The aims of this study were to (1) evaluate safety in an animal survival model and (2) compare direct portal vein (PV) versus transhepatic access of a first-order venule.

MATERIALS AND METHODS

Yorkshire pigs, weighing 40-55 kg. Procedures were performed under general anesthesia. PV was identified using a linear array echoendoscope and accessed with a 22-G fine needle aspiration needle preloaded with a digital pressure wire. Access was confirmed by portal venography. Mean digital pressure measurements were recorded over 30 seconds, and again after accessing a first-order portal venule in a transhepatic manner. Procedure times and video logs were maintained throughout. Animals were survived for 2 weeks. Repeat portal pressure measurements were performed before euthanasia and necropsy.

RESULTS

EUS-guided portal pressure measurements ranged from 3 to 11 mm Hg (mean 6.1) and were performed in a mean time of 214 seconds. There was no difference in measurement between the PV and first-order venule, or between baseline and 2-week follow-up. Five of 5 animals survived without incident. On necropsy, there was no evidence of thrombus or hemorrhage.

CONCLUSIONS

This study represents the first survival study after EUS-guided direct portal pressure measurements using a digital pressure wire. This method appears safe, straightforward, and precise. Measurements of the PV and a first-order portal venule appear equivalent, and serial measurement seems feasible.

Interventional endoscopic ultrasound: A new promising way for intrahepatic portosystemic shunt with portal pressure gradient

Background and Objectives:

Interventional endoscopic ultrasound (EUS) is a promising novel approach for intravascular interventions. The aim of this study was to assess the feasibility and safety of a EUS-guided intrahepatic portosystemic shunt (EGIPS) with portal pressure gradient measurement in a live porcine model.

Methods:

The left hepatic vein (LHV) or the inferior vena cava (IVC) was punctured with a needle that advanced into the portal vein (PV). A guidewire was then inserted into the PV, and a needle knife was used to create an intrahepatic fistula between LHV and PV. Portal pressure was recorded. The fistula was dilated with a balloon and a biliary metal stent was deployed between LHV and PV under sonographic and fluoroscopic observation. A portocavography validated the patency of the stent. Necropsies were realized after euthanasia.

Results:

Portosystemic stenting was achieved in 19/21 pigs. Final portocavography confirmed stent patency between PV and LHV or IVC in 17 pigs (efficacy of 81%): Four stents were dysfunctional as two were thrombosed and two were poor positioned. Portal pressure was documented before and after shunting in 20/21 pigs. Necropsies revealed that 19/21 procedures were transesophageal and two were transgastric. Hemoperitoneum and pneumothorax were found in one pig and hemothorax was found in two pigs. Morbidity was 14.2% (3/21 animals).

Conclusion:

EGIPS was feasible in 91% of cases, functional in 81%, with 14.2% per procedure morbidity. EGIPS still needs to be assessed in portal hypertension pig models with longer follow-up before being considered as an alternative when the transjugular intrahepatic portosystemic shunt fails.

EUS-guided portal pressure gradient measurement with a novel 25-gauge needle device versus standard transjugular approach: a comparison animal study

BACKGROUND AND AIMS

Portal hypertension (PH) is a serious adverse event of liver cirrhosis. The hepatic venous pressure gradient (HVPG) accurately reflects the degree of PH and is the single best prognostic factor in liver disease. Currently, portal pressure gradient (PPG) measurement is performed at interventional radiology (IR) with a standard transjugular approach requiring radiation and intravenous contrast. The aim of this study was to develop a novel EUS-guided system using a 25G FNA needle and compact manometer to directly measure PPG and to evaluate its performance and clinical feasibility.

METHODS

Experiments were performed in 3 swine that were under general anesthesia. Manometry was performed in venous (baseline and PH) and arterial (aorta) systems. The PH model was created by rapid Dextran-40 infusion peripherally. Under EUS guidance a 25G FNA needle with attached manometer was used to puncture (transgastric-transhepatic approach) and measure pressures in the portal vein, right hepatic vein (RHV), inferior vena cava (IVC), and aorta. With the IR approach, RHV (free and wedged), IVC, and aorta pressure were measured with an occlusion balloon. Pressure correlation was divided into 3 groups; low pressure (baseline), medium pressure (noncirrhotic portal hypertensive model), and high pressure (arterial). Correlation between the 2 methods of measurement was charted in scatter plots, and the Pearson's correlation coefficient (R) was calculated.

RESULTS

EUS identification, access, and manometry was successful in all targeted vessels. There was excellent correlation (R, .985-.99) between EUS and IR methods in all pressure ranges. No adverse event occurred.

CONCLUSIONS

This novel technique of EUS-PPG measurement using a 25G needle and novel manometer was feasible and demonstrated excellent correlation with the standard transjugular method throughout low, medium, and high pressure ranges.

EUS-guided portal pressure measurement using a digital pressure wire with real-time remote display: a novel, minimally invasive technique for direct measurement in an animal model

BACKGROUND AND AIMS

Hepatic venous pressure gradient (HVPG) currently serves as a surrogate for portal pressure measurement but has many limitations. We developed a novel technique for rapid and direct portal pressure measurements using a digital pressure wire delivered through an EUS-guided 22-gauge FNA needle. Our aims were to evaluate (1) the short-term safety and technical feasibility, (2) procedural duration and subjective workload assessment, and (3) accuracy compared with a transjugular criterion standard approach.

METHODS

The subjects were Yorkshire pigs, weighing 40 to 55 kg. The portal vein was identified by using a linear array echoendoscope and accessed with a commercially available 22-gauge FNA needle preloaded with a digital pressure wire. Access was confirmed by portal venography. Mean digital pressure measurements were recorded over 30 to 60 seconds, and the National Aeronautics and Space Administration Task Load Index was scored. The control measurements were conventional transjugular catheterization with a balloon occlusion catheter to obtain free and wedged hepatic pressures, with subsequent HVPG calculation.

RESULTS

The total time required for EUS identification and needle access of the portal vein, venography, and digital pressure measurement was less than 5 minutes in 5 of 5 pigs. The National Aeronautics and Space Administration Task Load Index scores revealed a low subjective workload. Baseline portal pressure measurements via EUS ranged from 5 mm Hg to 10 mm Hg (mean, 6.4 mm Hg). HVPG measurements were consistently ±1 mm Hg of portal pressure.

CONCLUSIONS

This study is the first report of direct EUS-guided portal pressure measurements by using a digital pressure wire. This method is routinely performed in minutes and provides real-time pressure tracings via wireless transmission. This novel approach for direct portal pressure measurement has the potential to replace traditional indirect HVPG measurements.

Endoscopic ultrasound-guided interventions in special situations

Endoscopic ultrasound (EUS) was introduced in 1982 and has since become a popular advanced procedure for diagnosis and therapeutic intervention. Initially, EUS was most commonly used for the diagnosis of pancreatobiliary diseases and tissue acquisition. EUS was first used for guided cholangiography in 1996, followed by EUS-guided biliary drainage in 2001. Advancements in equipment and endoscopic accessories have led to an expansion of EUS-guided procedures, which now include EUS-guided drainage of intra-abdominal abscesses or collections, intra-vascular treatment of refractory variceal and nonvariceal bleeding, transmural pancreatic drainage, common bile duct stone clearance, enteral feeding tube placement and entero-enteric anastomosis. Patients with surgically altered upper gastrointestinal anatomies have greatly benefited from EUS also. This systematic review describes and discusses EUS procedures performed in uncommon diseases and conditions, as well as applications on more vulnerable patients such as young children and pregnant women. In these cases, routine approaches do not always apply, and thus may require the use of innovative and unconventional techniques. Increased knowledge of such special applications will help increase the success rates of these procedures and provide a foundation for additional advances and utilizations of the technique.

Endoscopic ultrasonography-guided placement of a transhepatic portal vein stent in a live porcine model

Background and Objectives:

Percutaneous portal vein (PV) stent placement is used to manage PV occlusion or stenosis caused by malignancy. The use of endoscopic ultrasonography (EUS) has expanded to include vascular interventions. The aim of this study was to examine the technical feasibility and safety of EUS-guided transhepatic PV stent placement in a live porcine model.

Materials and Methods:

EUS-guided transhepatic PV stent placement was performed in six male miniature pigs under general anesthesia using forward-viewing echoendoscope. Under EUS guidance, the left intrahepatic PV was punctured with a 19-gauge fine-needle aspiration (FNA) needle and a 0.025 inch guidewire inserted through the needle and into the main PV. The FNA needle was then withdrawn and a needle-knife inserted to dilate the tract. Under EUS and fluoroscopic guidance, a noncovered metal stent was inserted over the guidewire and released into the main PV.

Results:

A PV stent was placed successfully in all six pigs with no technical problems or complications. The patency of the stent in the main PV was confirmed using color Doppler EUS and transhepatic portal venography. Necropsy of the first three animals revealed no evidence of bleeding and damage to intra-abdominal organs or vessels. No complications occurred in the remaining three animals during the 8 weeks observation period.

Conclusions:

EUS-guided transhepatic PV stent placement can be both technically feasible and safe in a live animal model.

Hepatic applications of endoscopic ultrasound: Current status and future directions

The diagnosis and staging of various gastrointestinal malignancies have been made possible with the use of endoscopic ultrasound, which is a relatively safe procedure. The field of endoscopic ultrasound is fast expanding due to advancements in therapeutic endoscopic ultrasound. Though various studies have established its role in gastrointestinal malignancies and pancreatic conditions, its potential in the field of hepatic lesions still remains vastly untapped. In this paper the authors attempt to review important and landmark trials, case series and case studies involving hepatic applications of endoscopic ultrasound, thus not only providing an overview of utilization of endoscopic ultrasound in various liver conditions but also speculating its future role.

Endoscopic ultrasound guided vascular access and therapy (with videos)

The continued need to develop minimally invasive alternatives to surgical and radiologic interventions has driven the development of endoscopic ultrasound (EUS)-guided treatments. EUS has now stepped into the therapeutic arena. EUS provides the unique advantage of both real-time imaging and access to structures within and adjacent to the gastrointestinal (GI) tract. Hence, EUS-guided therapeutic techniques continue to evolve in several directions enabling a variety of minimally invasive therapies for pancreatic and biliary pathologies. Furthermore, the close proximity of the GI tract to vascular structures in the mediastinum and abdomen permits EUS-guided vascular access and therapy. Studies have demonstrated several EUS-guided vascular interventions by using standard endoscopic accessories and available tools from the interventional radiology armamentarium. This article provides an overview of the literature including clinical and nonclinical studies for the management of nonvariceal and variceal GI bleeding, formation of intrahepatic portosystemic shunts (IPSS), and EUS-guided cardiac access and therapy.

Endoscopic ultrasound-guided intravascular therapy

The gastrointestinal tract provides a unique "window" to access vascular structures in the mediastinum and abdomen. The advent of interventional endoscopic ultrasound (EUS) has enabled access to these structures with a standard fine-needle aspiration (FNA) needle. Sclerosants, cyanoacrylate, and coils can be delivered through the lumen of the FNA needle. EUS-guided treatment of gastric varices has theoretical advantages over conventional endoscopy-guided treatment. Controlled studies are needed to determine the role of EUS-guided treatment for primary and secondary prevention of variceal bleeding. There is a growing list of novel indications for EUS-guided vascular therapy that include portal vein angiography and pressure measurements, intrahepatic portosystemic shunt placement, and micro coil embolization of vascular structures. Additionally, access and therapy of the heart and surrounding structures appears feasible.

Utility of endoscopic ultrasound in patients with portal hypertension

Endoscopic ultrasound (EUS) has revolutionized the diagnostic and therapeutic approach to patients with gastrointestinal disorders. Its application in patients with liver disease and portal hypertension is increasing. Patients with chronic liver disease are at risk for development of portal hypertension sequale such as ascites, spontaneous bacterial peritonitis and gastroesophageal varices. Bleeding esophageal and gastric varices are among the most common causes of mortality in patients with cirrhosis. Thus, early detection and treatment improve the outcome in this population. EUS can improve the detection and diagnosis of gastroesophageal varices and collateral veins and can provide endoscopic therapy of gastroesophageal varices such as EUS-guided sclerotherapy of esophageal collateral vessels and EUS-guided cynoacrylate (Glue) injection of gastric varices. EUS can also provide knowledge on the efficacy of pharmacotherapy of portal hypertension. Furthermore, EUS can provide assessment and prediction of variceal recurrence after endoscopic therapy and assessment of portal hemodynamics such as E-Flow and Doppler study of the azygous and portal veins. Moreover, EUS-guided fine needle aspiration may provide cytologic diagnosis of focal hepatic tumors and analysis of free abdominal fluid. Using specialized EUS-guided needle biopsy, a sample of liver tissue can be obtained to diagnose and evaluate for chronic liver disease. EUS-guided fine needle injection can be used to study portal vein pressure and hemodynamics, and potentially could be used to assist in exact measurement of portal vein pressure and placement of intrahepatic portosystemic shunt.

Endoscopic Ultrasound-Guided Treatment beyond Drainage: Hemostasis, Anastomosis, and Others

Since the introduction of endoscopic ultrasound (EUS) in the 1990s, it has evolved from a primarily diagnostic modality into an instrument that can be used in various therapeutic interventions. EUS-guided fine-needle injection was initially described for celiac plexus neurolysis. By using the fundamentals of this method, drainage techniques emerged for the biliary and pancreatic ducts, fluid collections, and abscesses. More recently, EUS has been used for ablative techniques and injection therapies for patients with for gastrointestinal malignancies. As the search for minimally invasive techniques continued, EUS-guided hemostasis methods have also been described. The technical advances in EUS-guided therapies may appear to be limitless; however, in many instances, these procedures have been described only in small case series. More data are required to determine the efficacy and safety of these techniques, and new accessories will be needed to facilitate their implementation into practice.

Standard imaging techniques for assessment of portal venous system and its tributaries by linear endoscopic ultrasound: a pictorial essay

Linear Endosonography has been used to image the Portal Venous System but no established standard guidelines exist. This article presents techniques to visualize the portal venous system and its tributaries by linear endosonography. Attempt has been made to show most of the first order tributaries and some second order tributaries of splenic vein, superior mesenteric vein and portal vein.

Standard imaging techniques for assessment of portal venous system and its tributaries by linear endoscopic ultrasound: a pictorial essay

Linear Endosonography has been used to image the Portal Venous System but no established standard guidelines exist. This article presents techniques to visualize the portal venous system and its tributaries by linear endosonography. Attempt has been made to show most of the first order tributaries and some second order tributaries of splenic vein, superior mesenteric vein and portal vein.

Splanchnic venous thrombosis and pancreatitis

Pancreatitis is an inflammatory process with local and systemic manifestations. One such local manifestation is thrombosis in splanchnic venous circulation, predominantly of the splenic vein. The literature on this important complication is very sparse. This review offers an overview of mechanism of thrombosis, its pathophysiology, diagnosis, and management in the setting of acute as well as chronic pancreatitis.

EUS-Guided Vascular Procedures: A Literature Review

Endoscopic ultrasound (EUS) is continuously stepping into the therapeutic arena, simultaneously evolving in different directions, such as the management of pancreatic and biliary diseases, celiac neurolysis, delivering local intratumoral therapy, and EUS-guided endosurgery. EUS-guided vascular procedures are also challenging, considering the variety of vascular pathology, proximity of the vascular structures to the GI tract wall, high resolution, and real-time guidance offering an attractive access route and precise delivery of the intervention. The literature on vascular therapeutic EUS demonstrates techniques for the management of upper GI variceal and nonvariceal bleeding, pseudoaneurysms, and coiling and embolization procedures, as well as the creation of intrahepatic portosystemic shunts. The paucity of studies, diversity of study designs, and the number of animal model studies hamper a systematic approach to the conclusion and decision making important to clinicians and healthcare policy makers. Nevertheless, theoretical benefits and findings up to date concerning technical feasibility, efficacy, and safety of the procedures drive further research and development in this rather young therapeutic arena.

On the implementation of an automated acoustic output optimization algorithm for subharmonic aided pressure estimation

Incident acoustic output (IAO) dependent subharmonic signal amplitudes from ultrasound contrast agents can be categorized into occurrence, growth or saturation stages. Subharmonic aided pressure estimation (SHAPE) is a technique that utilizes growth stage subharmonic signal amplitudes for hydrostatic pressure estimation. In this study, we developed an automated IAO optimization algorithm to identify the IAO level eliciting growth stage subharmonic signals and also studied the effect of pulse length on SHAPE. This approach may help eliminate the problems of acquiring and analyzing the data offline at all IAO levels as was done in previous studies and thus, pave the way for real-time clinical pressure monitoring applications. The IAO optimization algorithm was implemented on a Logiq 9 (GE Healthcare, Milwaukee, WI) scanner interfaced with a computer. The optimization algorithm stepped the ultrasound scanner from 0% to 100% IAO. A logistic equation fitting function was applied with the criterion of minimum least squared error between the fitted subharmonic amplitudes and the measured subharmonic amplitudes as a function of the IAO levels and the optimum IAO level was chosen corresponding to the inflection point calculated from the fitted data. The efficacy of the optimum IAO level was investigated for in vivo SHAPE to monitor portal vein (PV) pressures in 5 canines and was compared with the performance of IAO levels, below and above the optimum IAO level, for 4, 8 and 16 transmit cycles. The canines received a continuous infusion of Sonazoid microbubbles (1.5 μl/kg/min; GE Healthcare, Oslo, Norway). PV pressures were obtained using a surgically introduced pressure catheter (Millar Instruments, Inc., Houston, TX) and were recorded before and after increasing PV pressures. The experiments showed that optimum IAO levels for SHAPE in the canines ranged from 6% to 40%. The best correlation between changes in PV pressures and in subharmonic amplitudes (r=-0.76; p=0.24), and between the absolute PV pressures and the subharmonic amplitudes (r=-0.89; p<0.01) were obtained for the optimized IAO and 4 transmit cycles. Only for the optimized IAO and 4 transmit cycles did the subharmonic amplitudes differ significantly (p<0.01) before and after increasing PV pressures. A new algorithm to identify optimum IAO levels for SHAPE has been developed and validated with the best results being obtained for 4 transmit cycles. The work presented in this study may pave the way for real-time clinical applications of estimating pressures using the subharmonic signals from ultrasound contrast agents.

Investigating the efficacy of subharmonic aided pressure estimation for portal vein pressures and portal hypertension monitoring

The efficacy of using subharmonic emissions from Sonazoid microbubbles (GE Healthcare, Oslo, Norway) to track portal vein pressures and pressure changes was investigated in 14 canines using either slow- or high-flow models of portal hypertension (PH). A modified Logiq 9 scanner (GE Healthcare, Milwaukee, WI, USA) operating in subharmonic mode (f(transmit): 2.5 MHz, f(receive): 1.25 MHz) was used to collect radiofrequency data at 10-40% incident acoustic power levels with 2-4 transmit cycles (in triplicate) before and after inducing PH. A pressure catheter (Millar Instruments, Inc., Houston, TX, USA) provided reference portal vein pressures. At optimum insonification, subharmonic signal amplitude changes correlated with portal vein pressure changes; r ranged from -0.82 to -0.94 and from -0.70 to -0.73 for PH models considered separately or together, respectively. The subharmonic signal amplitudes correlated with absolute portal vein pressures (r: -0.71 to -0.79). Statistically significant differences between subharmonic amplitudes, before and after inducing PH, were noted (p ≤ 0.01). Portal vein pressures estimated using subharmonic aided pressure estimation did not reveal significant differences (p > 0.05) with respect to the pressures obtained using the Millar pressure catheter. Subharmonic-aided pressure estimation may be useful clinically for portal vein pressure monitoring.

EUS-guided vascular access and therapy

The gastrointestinal tract provides a unique window to access vascular structures in the mediastinum and abdomen. The advent of interventional endoscopic ultrasound (EUS) has enabled access to these structures with standard fine-needle aspiration. EUS-guided treatment of varices has been largely reserved as rescue therapy for refractory bleeding but has theoretic advantages over conventional endoscopy-guided treatment. Data are limited and multicenter, prospective controlled trials are needed to show clinical effectiveness and safety in humans. The development of new tools designed for EUS-guided vascular therapy is needed.

Usefulness of endoscopic ultrasonography in hepatology

Endoscopic ultrasonography (EUS) is used to evaluate patients with hepatobiliary diseases. The technique is useful for the diagnosis of esogastric varices in selected cases of portal hypertension, and to evaluate the pathogenic role and prognostic value of the collateral circulation in patients with this condition. When coupled with the Doppler technique, EUS can be used to guide injection sclerotherapy and to verify the obliteration of varices (particularly fundal varices) after endoscopic treatment. Hemodynamic changes induced in the collateral circulation by vasoactive drugs can also be measured with Doppler-EUS. Fine-needle aspiration under EUS guidance is useful in the diagnosis of focal liver lesions and perihepatic adenopathy, and in the evaluation of biliary tract diseases. New indications can be developed in the future after adequate experimental validation.

Interventional EUS

The American Society for Gastrointestinal Endoscopy (ASGE) Technology Committee provides reviews of new or emerging endoscopic technologies that have the potential to have an impact on the practice of GI endoscopy. Evidence-based methodology is used by performing a MEDLINE literature search to identify pertinent preclinical and clinical studies on the topic and a MAUDE (U.S. Food and Drug Administration Center for Devices and Radiological Health) database search to identify the reported complications of a given technology. Both are supplemented by accessing the "related articles" feature of PubMed and by scrutinizing pertinent references cited by the identified studies. Controlled clinical trials are emphasized, but, in many cases, data from randomized, controlled trials are lacking. In such cases, large case series, preliminary clinical studies, and expert opinions are used. Technical data are gathered from traditional and Web-based publications, proprietary publications, and informal communications with pertinent vendors. For this review, the MEDLINE database was searched through August 2009 by using the keywords "interventional endoscopic ultrasound," "EUS," and "interventional endoscopy." Reports on Emerging Technologies are drafted by 1 or 2 members of the ASGE Technology Committee, reviewed and edited by the committee as a whole, and approved by the Governing Board of the ASGE. These reports are scientific reviews provided solely for educational and informational purposes. Reports on Emerging Technologies are not rules and should not be construed as establishing a legal standard of care or as encouraging, advocating, requiring, or discouraging any particular treatment or payment for such treatment.