Calculation of esophageal variceal wall tension by direct sonographic and manometric measurements

Sudden Death Caused by Gastroesophageal Varices Rupture: Insights From an Autopsy-Based Case Series Unraveling the Pathological Events

Sudden death is characterized by natural yet unexpected death, typically occurring within 24 hours from the onset of the patient's symptoms. While the majority of sudden deaths stem from cardiac issues/causes, there are instances where non-cardiac factors are at play. One such scenario involves hemorrhage from ruptured esophageal varices, a complication that stems from portal hypertension. Portal hypertension can manifest due to a range of pre-hepatic, hepatic, and post-hepatic conditions, with liver cirrhosis being the primary culprit. Although sudden death cases linked to the gastrointestinal system are relatively rare, the rupture of gastroesophageal varices, precipitating severe morbidity and a high mortality rate, represents a life-threatening condition. In this context, we present a case series encompassing five instances of sudden natural deaths arising from the rupture of gastroesophageal varices.

Editorial: variceal haemorrhage-under pressure, not the probe pushing down on me

This article is linked to Odewole et al papers. To view these articles, visit https://doi.org/10.1111/apt.16860

So-Called Lamina Cribrosa Defects May Mitigate IOP-Induced Neural Tissue Insult

Purpose

The prevailing theory about the function of lamina cribrosa (LC) connective tissues is that they provide structural support to adjacent neural tissues. Missing connective tissues would compromise this support and therefore are regarded as “LC defects”, despite scarce actual evidence of their role. We examined how so-called LC defects alter IOP-related mechanical insult to the LC neural tissues.

Methods

We built numerical models incorporating LC microstructure from polarized light microscopy images. To simulate LC defects of varying sizes, individual beams were progressively removed. We then compared intraocular pressure (IOP)-induced neural tissue deformations between models with and without defects. To better understand the consequences of defect development, we also compared neural tissue deformations between models with partial and complete loss of a beam.

Results

The maximum stretch of neural tissues decreased non-monotonically with defect size. Maximum stretch in the model with the largest defect decreased by 40% in comparison to the model with no defects. Partial loss of a beam increased the maximum stretch of neural tissues in its adjacent pores by 162%, compared with 63% in the model with complete loss of a beam.

Conclusions

Missing LC connective tissues can mitigate IOP-induced neural tissue insult, suggesting that the role of the LC connective tissues is more complex than simply fortifying against IOP. The numerical models further predict that partial loss of a beam is biomechanically considerably worse than complete loss of a beam, perhaps explaining why defects have been reported clinically but partial beams have not.

Variceal bleeding is aggravated by portal venous invasion of hepatocellular carcinoma: a matched nested case-control study

Background

We hypothesized that portal vein tumor thrombosis (PVTT) in hepatocellular carcinoma (HCC) increases portal pressure and causes esophageal varices and variceal bleedings. We examined the incidence of high-risk varices and variceal bleeding and determined the indications for variceal screening and prophylaxis.

Methods

This study included 1709 asymptomatic patients without any prior history of variceal hemorrhage or endoscopic prophylaxis who underwent upper endoscopy within 30 days before or after initial anti-HCC treatment. Of these patients, 206 had PVTT, and after 1:2 individual matching, 161 of them were matched with 309 patients without PVTT. High-risk varices were defined as large/medium varices or small varices with red-color signs and variceal bleeding. Bleeding rates from the varices were compared between matched pairs. Risk factors for variceal bleeding in the entire set of patients with PVTT were also explored.

Results

In the matched-pair analysis, the proportion of high-risk varices at screening (23.0% vs. 13.3%; P = 0.003) and the cumulative rate of variceal bleeding (4.5% vs. 0.4% at 1 year; P = 0.009) were significantly greater in the PVTT group. Prolonged prothrombin time, lower platelet count, presence of extrahepatic metastasis, and Vp4 PVTT were independent risk factors related to high-risk varices in the total set of 206 patients with PVTT (Adjusted odds ratios [95% CIs], 1.662 [1.151–2.401]; 0.985 [0.978–0.993]; 4.240 [1.783–10.084]; and 3.345 [1.457–7.680], respectively; Ps < 0.05). During a median follow-up of 43.2 months, 10 patients with PVTT experienced variceal bleeding episodes, 9 of whom (90%) had high-risk varices. Presence of high-risk varices and sorafenib use for HCC treatment were significant predictors of variceal bleeding in the complete set of patients with PVTT (Adjusted hazard ratios [95% CIs], 26.432 [3.230–216.289]; and 5.676 [1.273–25.300], respectively; Ps < 0.05).

Conclusions

PVTT in HCC appears to increase the likelihood of high-risk varices and variceal bleeding. In HCC patients with PVTT, endoscopic prevention could be considered, at least in high-risk variceal carriers taking sorafenib.

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.

Lamina Cribrosa Pore Shape and Size as Predictors of Neural Tissue Mechanical Insult

Purpose

The purpose of this study was to determine how the architecture of the lamina cribrosa (LC) microstructure, including the shape and size of the lamina pores, influences the IOP-induced deformation of the neural tissues within the LC pores using computational modeling.

Methods

We built seven specimen-specific finite element models of LC microstructure with distinct nonlinear anisotropic properties for LC beams and neural tissues based on histological sections from three sheep eyes. Changes in shape (aspect ratio and convexity) and size (area and perimeter length) due to IOP-induced hoop stress were calculated for 128 LC pores. Multivariate linear regression was used to determine if pore shape and size were correlated with the strain in the pores. We also compared the microstructure models to a homogenized model built following previous approaches.

Results

The LC microstructure resulted in focal tensile, compressive, and shear strains in the neural tissues of the LC that were not predicted by homogenized models. IOP-induced hoop stress caused pores to become larger and more convex; however, pore aspect ratio did not change consistently. Peak tensile strains within the pores were well predicted by a linear regression model considering the initial convexity (negative correlation, P < 0.001), aspect ratio (positive correlation, P < 0.01), and area (negative correlation, P < 0.01). Significant correlations were also found when considering the deformed shape and size of the LC pores.

Conclusions

The deformation of the LC neural tissues was largely dependent on the collagenous LC beams. Simple measures of LC pore shape and area provided good estimates of neural tissue biomechanical insult.

Management of gastric variceal bleeding: Role of endoscopy and endoscopic ultrasound

Gastric varices (GVs) are notorious to bleed massively and often difficult to manage with conventional techniques. This mini-review addresses endoscopic management principles for gastric variceal bleeding, including limitations of ligation and sclerotherapy and merits of endoscopic variceal obliteration. The article also discusses how emerging use of endoscopic ultrasound provides optimism of better diagnosis, improved classification, innovative management strategies and confirmatory tool for eradication of GVs.

Invasive and non-invasive techniques for detecting portal hypertension and predicting variceal bleeding in cirrhosis: a review

Portal hypertension is a severe syndrome that may derive from pre-sinusoidal, sinusoidal, and post-sinusoidal causes. As a consequence, several complications (i.e. ascites, oesophageal varices) may develop. In sinusoidal portal hypertension, hepatic venous pressure gradient (HVPG) is a reliable method for defining the grade of portal pressure, establishing the effectiveness of the treatment, and predicting the occurrence of complications; however, some questions exist regarding its ability to discriminate bleeding from non-bleeding varices in cirrhotic patients. Other imaging techniques (transient elastography, endoscopy, endosonography, and duplex Doppler sonography) for assessing causes and complications of portal hypertensive syndrome are available and may be valuable for the management of these patients. In this review, we evaluate invasive and non-invasive techniques currently employed to obtain a clinical prediction of deadly complications, such as variceal bleeding in patients affected by sinusoidal portal hypertension, in order to create a diagnostic algorithm to manage them. Again, HVPG appears to be the reference standard to evaluate portal hypertension and monitor the response to treatment, but its ability to predict several complications and support management decisions might be further improved through the diagnostic combination with other imaging techniques.

Minimally invasive measurement of esophageal variceal pressure and wall tension (with video)

BACKGROUND

There is no simple method to measure intravariceal pressure in patients with esophageal varices.

OBJECTIVE

Our purpose was to develop a new noninvasive technique to measure resting intravariceal pressure and wall tension.

DESIGN

A model was developed. A long balloon (varix) was fitted inside an airtight cylinder (esophagus). Fluid ran through the model varices to maintain 5 different constant pressures. An endoscope was placed in the model esophagus, and pressure was increased by air insufflation. The endoscopy and pressure readings from the esophagus and varix were recorded continuously until variceal collapse.

SETTING

Patient studies were done in an endoscopy suite with the patient under fentanyl and midazolam sedation.

PATIENTS

Esophageal pressure was measured during air insufflation in patients with varices until the varices collapsed. EUS was used to measure radius and wall thickness to calculate wall tension.

RESULTS

In the varix model, the mean (SD) intraluminal esophageal pressures at variceal flattening for the model varices at 5, 10, 15, 20, and 25 mm Hg were 5.69 (0.34), 11 (0.32), 15.72 (0.51), 21.55 (0.63), and 25.8 (0.14) mm Hg. The correlation between actual and measured variceal pressure in the model at variceal flattening was r = 0.98. In the patients, a total of 10 varices in 3 patients were evaluated. The mean (SD) for the varices in each subject was 12.16 (2.4), 23.2 (1.3), and 6.5 (2.2) mm Hg for subjects 1, 2, and 3, respectively.

CONCLUSION

Standard endoscopy with air insufflation and manometry can be used as an accurate, simple, and reproducible method to measure intravariceal pressure.

Portal venous flow pattern as a useful tool for predicting esophageal varix bleeding in cirrhotic patients

This study aimed to evaluate whether (1) the portal venous flow pattern determined by color Doppler sonography could be related to the clinical severity of liver cirrhosis and (2) whether the flow patterns differ between patients with bleeding and nonbleeding esophageal varices. One hundred twenty-nine cirrhotic patients and 60 noncirrhotic healthy controls were enrolled after endoscopic survey for the presence of esophageal varices. Each patient received color Doppler echography to define the pattern of blood flow direction as hepatopetal or nonhepatopetal (hepatofugal, turbulence, and bidirection) in type. The patients with esophageal varices were further categorized into two groups: with recent bleeding (BEV; n = 99) and without recent bleeding (NBEV; n = 30). More patients in the BEV group (72.7%) had a nonhepatopetal Doppler flow pattern than in the control group (1.7%) and NBEV group (13.3%) (P < 0.001). Among the 129 cirrhotic patients, the nonhepatopetal flow pattern of the portal vein was higher in 96% of Child-Pugh grade C patients than in 41.8% of grade A patients and 57.6% of grade B patients (P < 0.05). Moreover, for those cirrhotic patients with Child-Pugh grades A and B, the nonhepatopetal Doppler flow pattern was more commonly found in the BEV group than in the NBEV group (63.0 vs. 13.8%; odds ratio, 10.64; 95% CI, 0.03-0.299; P < 0.001). Portal venous blood flow pattern is related to severity of cirrhosis. The presence of a nonhepatopetal flow pattern implicates an increased risk of esophageal varices bleeding, especially for those cirrhotic patients with Child-Pugh grades A and B.

Ultrasound system to measure esophageal varix pressure: an in vitro validation study

We report our experience with an ultrasound system to measure esophageal varix pressure in an in vitro model. The ultrasound system consists of a 12.5 MHz frequency intraluminal ultrasound probe, a water infusion catheter, and a manometry catheter, all contained within a nondistensible latex bag. Esophagi and external jugular veins were harvested from five pigs. The vein and ultrasound system were placed inside the esophagus. One end of the vein was connected to a water reservoir to modulate its pressure; the other end was connected in two different ways to simulate hydrodynamic and hydrostatic flow conditions. The bag was inflated with water until vein occlusion was discernible on the ultrasound images. The influences of vein pressure, vein cross-sectional area and esophageal elasticity on the ultrasound measurement of vein pressure were assessed. A total of 108 trials were performed at nine different vein pressures. Complete vein occlusion occurred when the bag pressure was slightly greater (1.4 +/- 0.7 mmHg) than the vein pressure. For a vein pressure of 25 mmHg, the average occlusion and opening pressures were 27 +/- 0.2 and 25.7 +/- 0.3 mmHg, respectively (P < .05) suggesting that the vein opening pressure on the ultrasound images is more accurate than the vein closing pressure. In conclusion, the ultrasound technique can accurately measure intravariceal pressure in vitro. The bag pressure at the point of vein reopening is the best determinant of the vein pressure.

Mechanics and hemodynamics of esophageal varices during peristaltic contraction

Our hypothesis states that variceal pressure and wall tension increase dramatically during esophageal peristaltic contractions. This increase in pressure and wall tension is a natural consequence of the anatomy and physiology of the esophagus and of the esophageal venous plexus. The purpose of this study was to evaluate variceal hemodynamics during peristaltic contraction. A simultaneous ultrasound probe and manometry catheter was placed in the distal esophagus in nine patients with esophageal varices. Simultaneous esophageal luminal pressure and ultrasound images of varices were recorded during peristaltic contraction. Maximum variceal cross-sectional area and esophageal luminal pressures at which the varix flattened, closed, and opened were measured. The esophageal lumen pressure equals the intravariceal pressure at variceal flattening due to force balance laws. The mean flattening pressures (40.11 +/- 16.77 mmHg) were significantly higher than the mean opening pressures (11.56 +/- 25.56 mmHg) (P < or = 0.0001). Flattening pressures >80 mmHg were generated during peristaltic contractions in 15.5% of the swallows. Variceal cross-sectional area increased a mean of 41% above baseline (range 7-89%, P < 0.0001) during swallowing. The peak closing pressures in patients that experience future variceal bleeding were significantly higher than the peak closing pressures in patients that did not experience variceal bleeding (P < 0.04). Patients with a mean peak closing pressure >61 mmHg were more likely to bleed. In this study, accuracy of predicting future variceal bleeding, based on these criteria, was 100%. Variceal models were developed, and it was demonstrated that during peristaltic contraction there was a significant increase in intravariceal pressure over baseline intravariceal pressure and that the peak intravariceal pressures were directly proportional to the resistance at the gastroesophageal junction. In conclusion, esophageal peristalsis in combination with high resistance to blood flow through the gastroesophageal junction leads to distension of the esophageal varices and an increase in intravariceal pressure and wall tension.

Catheter-based intraluminal sonography

With the development of interventional and minimally invasive surgical techniques in the last decade, a strong interest in intraluminal sonography has arisen because of the need for better imaging information and management of the interventional procedure. High-resolution intraluminal sonography is a unique approach for the evaluation of a wide range of abnormalities within the luminal structures throughout the body. This imaging technique has been able to obtain information not available with even the most sophisticated percutaneous sonography, CT, or MRI. The uniqueness of this approach has led to extensive research, establishing a variety of clinical applications. These miniature catheter-based transducers have become important supplemental tools in the evaluation of the urinary and gastrointestinal tracts. Other areas need to be evaluated more thoroughly before efficacy is established, but the concept of using miniature transducers has shown promise in many areas of the body. This should lead to the provision of important information for decision making relative to patient care and surgical intervention. In the future, with projected technical progress, intraluminal sonography should substantially improve its diagnostic capabilities.

Risk of esophageal variceal bleeding based on endoscopic ultrasound evaluation of the sum of esophageal variceal cross-sectional surface area

OBJECTIVE

The aim of this study was to evaluate the risk of future variceal bleeding, based on the endoscopic ultrasound measurement of the sum of the cross-sectional surface area (CSA) of all of the esophageal varices in the distal esophagus.

METHODS

Twenty-eight patients with portal hypertension and esophageal varices, but no prior history of variceal bleeding, were evaluated using endoscopic ultrasound (20-MHz ultrasound probe, Microvasive, Boston, MA; Olympus, Tokyo, Japan). The entire esophagus was imaged, and an image was selected at a point where the varices appeared the largest. This image was digitized, and the sum of the CSA of all of the varices was measured (Image Pro Plus, Silver Springs, MD) by an investigator blinded to the patients' clinical status. The follow-up time for each patient was calculated (time to first bleed, time to liver transplantation, time to death, or time to the end of study). The Cox Proportional Hazards Model was used to determine if there was a significant difference between the sums of the CSA in the patients who bled compared with those who did not bleed. An OR was calculated to determine the risk of future variceal bleeding based on the sum of the CSA as measured in cm(2)/month. Positive and negative predictive values were calculated for future variceal bleeding.

RESULTS

Six of 28 patients (21%) experienced esophageal variceal bleeding on follow-up. The mean CSA +/- SEM of the sum of the esophageal varices in these patients was 0.77 cm(2) +/- 0.31 cm(2) (range 0.07-2.09 cm(2)). The mean time to bleeding was 15.5 months +/- 4.95 months (range 1-29 months). Twenty-two of 28 patients (79%) did not experience variceal bleeding. The mean CSA +/- SEM of the sum of the varices in these patients was 0.36 cm(2) +/- 0.08 cm(2) (range 0.02-1.19 cm(2)). The mean time to follow-up was 35.7 months +/- 6.69 months (range 1.2-103.2 months). The sum of the CSA between the patients who bleed and those who did not bleed was significantly different at the p < 0.018 level. The OR for the risk of variceal bleeding for each one cm(2) difference in the sum of the CSA per month was 6.34. Using a cutoff of 0.45 cm(2), the sensitivity and specificity for future variceal bleeding was 83% and 75%, respectively.

CONCLUSIONS

There is a significant difference (p < 0.018) in the sum of the esophageal variceal CSA between those patients who will experience future variceal bleeding and those who will not. There is a 76-fold increase per year in the risk of future variceal bleeding for each one cm(2) increase in variceal CSA. Using a cutoff value for the CSA of 0.45 cm(2), the sensitivity and specificity for future variceal bleeding above and below this point is 83% and 75%, respectively.

A new device for measuring esophageal variceal pressure

BACKGROUND

Esophageal varices are a frequent source of bleeding in patients with cirrhosis. Elevated intravariceal pressure is associated with variceal bleeding. There is no simple, easy-to-use device for noninvasive measurement of intravariceal pressure. The purposes of this study were to develop a noninvasive method for measuring intravariceal pressure, and to develop a model of esophageal varices that can be used to test this pressure measurement device.

METHODS

A variceal pressure measurement device was constructed by placing a 20 MHz US transducer in a latex balloon catheter sheath and attaching the catheter to a pressure transducer. The pressure measurement device was passed though the accessory channel of a large-channel endoscope and tested in blinded fashion by using tip deflection to compress each of 4 variceal models with the device. The pressure within each model was measured 10 times by 2 separate investigators blinded to the actual pressures. The mean (SD) pressure was calculated for each model. The variceal models were made of nitrocellulose dialysis tubing filled with water. Each "varix" had the same diameter but a different intraluminal pressure (5.5, 10, 15, 21.5 mm Hg).

OBSERVATIONS

The correlation coefficient between the actual and measured "varix" pressures for the first investigator (L.S.M.) was r = 0.96: 99% CI [0.93, 0.98]. For the varix models with pressures of 21.5, 15, 10, and 5.5 the percent errors were, respectively, 9.5, 3.9, 5.1, and 0.7. The correlation coefficient between the actual and measured varix pressures for the second investigator (Q.D.) was r = 0.97: 99% CI [0.94, 0.98]. For the varix models with pressures of 21.5, 15, 10, and 5.5 the percent errors were, respectively, 10.3, 3.4, 9.8, and 1.1. The correlation coefficient between the 2 investigators (L.S.M., Q.D.) for the varix model pressures was r = 0.97: 99% CI [0.95, 0.99].

CONCLUSION

The variceal pressure measuring device developed for this study measured intravariceal pressure in a model varix with a low percent error and high correlation to the actual pressures. Intraobserver and interobserver variability was low.

The Law of Laplace and its relevance to contemporary medicine and rehabilitation

OBJECTIVE

To show that the Law of Laplace is not only a historical curiosity but also remains relevant to our daily teaching and clinical activities.

DATA SOURCES

Comprehensive MEDLINE (1960-2000) and CINAHL (1982-2000) computer literature searches performed by using key words such as Law of Laplace, Laplace, and Laplace relationship. Additional references were obtained from the bibliographies of the selected articles. Supplementary searches were also made by using various Internet search engines.

STUDY SELECTION

Primary references were used whenever possible.

DATA EXTRACTION

A single reviewer assessed all references and extracted information relevant to the Law of Laplace.

DATA SYNTHESIS

Although the Law of Laplace is attributed to Pierre Simon de Laplace, Laplace may not deserve the credit for the discovery. Nevertheless, the relationship (T [tension] alpha P [pressure] R [radius]) is easily derived and improves our understanding of the physiologic basis of many of our medical and rehabilitation practices. For example, the Law provides an insight into the mechanism of action of compression garments and lumbosacral orthoses, an understanding of the role of uterine muscle during delivery, and a reason why cesarean sections are made in the lower uterus. In addition, the Law explains many aspects of such diverse phenomena as penile erection, compartment syndromes, and peripheral edema. Perhaps most important, the Law explains the basis of many common medical practices that we use to promote bladder emptying, to control edema, and to plan surgery.

CONCLUSION

The Law of Laplace explains the mechanism of a wide range of physiologic phenomena. Unfortunately, even though it was developed about 200 years ago, the insights it provides us are often underused. More consideration of its implications can improve our clinical practice, our teaching, and our enjoyment of medicine.

Endoluminal sonography of the genitourinary and gastrointestinal tracts

OBJECTIVE

Endoluminal sonography with high-frequency catheter-based transducers is a technique well suited to imaging structures beyond the lumen of the hollow viscus. The purpose of this article was to review some aspects of endoluminal sonography, including instrumentation, clinical applications in the gastrointestinal and genitourinary tracts, and its three-dimensional reconstruction.

METHODS

The development of 6F to 10F catheter-based ultrasonic probes has made this technique available for use within a variety of lumina. Endoluminal sonography with frequencies of 9 to 20 MHz has been used for evaluation of a wide range of abnormalities in both the genitourinary and gastrointestinal tracts.

RESULTS

Uses in the gastrointestinal tract include quantification of esophageal varices, distinguishing between various submucosal lesions, and measuring the degree of fibrosis in scleroderma. In the genitourinary system, endoluminal sonography has been used to guide collagen injection, to diagnose urethral diverticula and upper tract neoplasms, to locate crossing vessels and septa for guiding endopyelotomy, and to identify submucosal calculi.

CONCLUSIONS

High-resolution endoluminal sonography is a new sonographic approach for evaluation of the genitourinary and gastrointestinal tracts. This should lead to the expansion of the diagnostic capabilities of sonography, providing important information for decision making relative to patient care and minimally invasive interventional procedures. Reconstructed three-dimensional endoluminal sonography has the potential to become a valuable tool in both the research and clinical areas.

Three-dimensional esophageal varix model quantification of variceal volume by high-resolution endoluminal US

BACKGROUND

The purpose of this study was to evaluate the accuracy and reproducibility of three-dimensional volume measurements by high-resolution endoluminal ultrasound in an esophageal varix model.

METHODS

An esophageal varix model was made by filling three esophageal dilatation catheters with various volumes of water. A 20 MHz ultrasonography transducer was then pulled along the length of the catheters at a constant rate (1.25 mm/sec) while videotaping the procedure. Cross-sectional surface area measurements of each catheter were taken every second and the cross-sectional surface area was multiplied by the length of each catheter, as determined by high-resolution endoluminal ultrasound, to determine the volume in each catheter. Interobserver variability was calculated, and three-dimensional reconstruction was performed.

RESULTS

The measured volumes corresponded closely with the actual volumes with an error ranging from 0% to 15.4%. The correlation between actual and measured volumes was r = 0.988. The interobserver variability ranged from r = 0.951 to r = 0.994. Actual esophageal varices were then imaged in a similar fashion to determine the feasibility of this method in patients with esophageal varices.

CONCLUSIONS

High-resolution endoluminal ultrasound is an accurate and reproducible method of measuring volumes in an esophageal varix model and can be used in a clinical setting to determine variceal volume. Volume studies are now underway in human subjects.