Validation of color Doppler EUS for azygos blood flow measurement in patients with cirrhosis: application to the acute hemodynamic effects of somatostatin, octreotide, or placebo

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.

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.

Validation of endoscopic ultrasound measured flow rate in the azygos vein using a flow phantom

Increase in flow rate within the azygos vein may be used as an indicator of the degree of liver cirrhosis. The aim of this study was to evaluate the error in measurement of flow rate using a commercial endoscopic ultrasound system, using a flow phantom that mimicked azygos vein depth, diameter and flow rate. Diameter was underestimated in all cases, with an average underestimation of 0.09 cm. Maximum velocity was overestimated, by 4 ± 4% at 50°, 11 ± 3% at 60° and 23 ± 7% at 70°. The increase in error with beam-vessel angle is consistent with the error as arising from geometric spectral broadening. Flow was underestimated by amounts up to 33%, and it is noted that the overestimation caused by geometric spectral broadening is in part compensated by underestimation of diameter. It was concluded that measurement of flow rate using a commercially available endoscopic ultrasound system is dependent on the beam-vessel angle, with errors up to 33% for typical vessel depths, diameter and beam-vessel angle.

Octreotide bolus injection and azygos blood flow in patients with cirrhosis: is the effect really predictable?

BACKGROUND

Octreotide (OCT) improves the management of variceal bleeding, but the pattern of administration is not clearly defined. Available data show a transient decrease in portal pressure and azygos blood flow (AzBF) after OCT bolus injection with desensitization at readministration.

AIM

To explore the sustained hemodynamic effects of OCT and changes associated with readministration at 60 minutes on AzBF in patients with portal hypertension.

PATIENTS AND METHODS

AzBF was measured invasively (thermodilution technique) in 12 patients at baseline and at 10 minutes intervals after OCT 50-μg IV bolus for a total of 60 minutes. Readministration of OCT was followed by AzBF measurement for another 15 minutes. Patients [age 51.4 y (30 to 69)] had cirrhosis (alcoholic in 9 patients; Pugh's score 8.8±0.3), portal hypertension (HVPG 19±1 mm Hg), and elevated AzBF (658±138 mL/min).

RESULTS

The bolus of OCT was followed at 10 minutes by a 34% decline in AzBF as compared with baseline value. This AzBF reduction was sustained over the 60-minute study period (-36%±1.4%) with the values that remained decreased as compared with baseline (P<0.01). Mean arterial pressure remained stable. At 60 minutes, the repeat OCT bolus induced a further significant (P<0.01) decline in AzBF, although the response was blunted (-18%±1.2%).

CONCLUSION

The AzBF showed a sustained decrease of value after a bolus injection of 50-μg OCT. A further hemodynamic response is detectable at OCT readministration after 60 minutes. The pattern of hemodynamic response to OCT may not be uniform among cirrhotics.

Endoscopic ultrasonography for the evaluation of portal hypertension

Since the 1980s, endoscopic ultrasonography (EUS) has been useful in the evaluation of portal hypertension, either for the diagnostic aspects or for the evaluation of therapy and risk of bleeding. More recently, it has been described as a method for guiding interventions such as variceal injection, portal vein catheterization, or even for creating an intrahepatic portosystemic shunt in the animal laboratory. The new generation of radial electronic echoendoscopes is equipped with color Doppler capability, allowing for measurement of any hemodynamic parameter of the portal circulation. This article summarizes the current knowledge on the role of EUS for the evaluation of portal hypertension.

Endoscopic ultrasonography and portal hypertension: where are we in 2009?

Endoscopic ultrasonography is currently a sensitive diagnostic and therapeutic tool with established indications, but its role in the management of portal hypertension is not well defined. This article briefly reviews indications, technologic improvements, diagnostic and interventional applications of endoscopic ultrasonography in portal hypertension.

Systematic review: endoscopic and imaging-based techniques in the assessment of portal haemodynamics and the risk of variceal bleeding

BACKGROUND

Invasive measurement of the hepatic venous pressure gradient (HVPG) is regarded as the gold standard for risk stratification and the evaluation of pharmaceutical agents in patients with portal hypertension.

AIM

To review the techniques for endoscopic and imaging-based assessment of portal haemodynamics, with particular emphasis on trials where the results were compared with HVPG or direct portal pressure measurement.

METHODS

Systematic search of the MEDLINE electronic database with keywords: portal hypertension, variceal bleeding, variceal pressure, endoscopic ultrasound, Doppler ultrasonography, magnetic resonance angiography, CT angiography, hepatic venous pressure gradient.

RESULTS

Computed tomography angiography and endoscopic ultrasound (EUS) have been both employed for the diagnosis of complications of portal hypertension and for the evaluation of the efficacy of endoscopic therapy. Colour Doppler ultrasonography and magnetic resonance angiography has given discrepant results. Endoscopic variceal pressure measurements either alone or combined with simultaneous EUS, correlate well with HVPG and risk of variceal bleeding and have a low interobserver variability.

CONCLUSIONS

Endoscopic and imaging-based measurements of portal haemodynamics provide an alternate means for the assessment of complications of portal hypertension. Further studies are required to validate their use in risk stratification and the evaluation of drug therapies in patients with portal hypertension.

A 3-month course of long-acting repeatable octreotide (sandostatin LAR) improves portal hypertension in patients with cirrhosis: a randomized controlled study

OBJECTIVE

In patients with cirrhosis, acute octreotide administration may transiently decrease the hepatic venous pressure gradient (HVPG). Information on long-term effects of octreotide is limited and controversial. We evaluated portal and systemic hemodynamics following a prolonged administration of long-acting octreotide in patients with cirrhosis.

METHODS

Eighteen cirrhotic patients (alcoholic 12; age 55 yr [44-69]; Pugh's score 7.8; HVPG 17.3 mmHg [12-22]), no steatohepatitis on histology, were randomized to intramuscular octreotide 20 mg (group A) q 4 wk for 3 months or placebo (group B) in a double-blind fashion. At baseline and 3 months, we measured the HVPG, systemic hemodynamics, endothelin-1 (ET-1), and vascular endothelial growth factor (VEGF) in hepatic venous blood.

RESULTS

Patients remained compensated except for one episode of infection in each group. At 3 months, the HVPG decreased in group A but not in group B (16.5 +/- 1.3 to 11.8 +/- 1.5 mmHg, P < 0.01; 18.2 +/- 1 to 17 +/- 1.1 mmHg, P= 0.4). Systemic hemodynamics and liver function remained unchanged. In group A, but not in group B, VEGF decreased (21.2 +/- 4.7 to 13.7 +/- 3.5 pg/mL, P < 0.01; 22.5 +/- 7.8 to 19.2 +/- 5.4 pg/mL, P= 0.4). ET-1 remained stable. Changes in HVPG and VEGF were correlated (r = 0.49, P < 0.05).

CONCLUSIONS

Three months of long-acting octreotide in selected cirrhotic patients with portal hypertension decreases the HVPG independent of systemic hemodynamics and liver function. The decrease in VEGF blood levels suggests an improvement in splanchnic hyperemia.

Evaluation of the effects of combined endoscopic variceal ligation and splenectomy with pericardial devascularization on esophageal varices

AIM: To detect the hemodynamic alterations in collateral circulation before and after combined endoscopic variceal ligation (EVL) and splenectomy with pericardial devascularization by ultrasonography, and to evaluate their effect using hemodynamic parameters.

METHODS: Forty-three patients with esophageal varices received combined EVL and splenectomy with pericardial devascularization for variceal eradication. The esophageal vein structures and azygos blood flow (AZBF) were detected by endoscopic ultrasonography and color Doppler ultrasound. The recurrence and rebleeding of esophageal varices were followed up.

RESULTS: Patients with moderate or severe varices in the esophageal wall and those with severe peri-esophageal collateral vein varices had improvements after treatment, while the percentage of patients with severe para-esophageal collateral vein varices decreased from 54.49% to 2.33%, and the percentage of patients with detectable perforating veins decreased from 79.07% to 4.65% (P < 0.01). Color Doppler flowmetry showed a significant decrease both in AZBF (43.00%, P < 0.05) and in diameter of the azygos vein (28.85%, P < 0.05), while the blood flow rate was unchanged. The recurrence rate of esophageal varices was 2.5% (1/40, mild), while no re-bleeding cases were recorded.

CONCLUSION: EVL in combination with splenectomy with pericardial devascularization can block the collateral veins both inside and outside of the esophageal wall, and is more advantagious over splenectomy in combination with pericardial devascularization or EVL in preventing recurrence and re-bleeding of varices.

Endoscopic ultrasonography in the diagnosis and management of portal hypertension. Where are we next?

Endoscopic ultrasonography has recently emerged as an accurate, non-invasive and reproducible alternative means of providing data for patients with portal hypertension. It is well established that endoscopic ultrasonography is more sensitive than endoscopy in the diagnosis of gastric varices. Dilated venous abnormalities outside the gastrooesophageal lumen, which cannot be diagnosed by endoscopy, are readily visible with endoscopic ultrasonography or miniature probes. Endoscopic ultrasonography is also useful to predict the risk of variceal recurrence and thus the risk of rebleeding after endotherapy which cannot be reliably predicted using endoscopy alone. The introduction of echo endoscopes equipped with Doppler facilities has allowed the sonographic visualisation of the vessels and the evaluation of vascular blood flow along with possible morphologic and haemodynamic changes after endoscopic or pharmacological therapy. However, despite its theoretical advantages, relative evidence suggests that in the clinical setting of portal hypertension, endoscopic ultrasonography remains an investigational tool with limited clinical applications.

Utilization of the delay phenomenon improves blood flow and reduces collagen deposition in esophagogastric anastomoses

OBJECTIVE

Complications of anastomotic healing are a common source of morbidity and mortality after esophagogastrostomy. The delay phenomenon is seen when a skin flap is partially devascularized in a staged procedure prior to its definitive placement, resulting in increased blood flow at the time of grafting. This effect may be applied to esophagogastrectomy, potentially reducing anastomotic complications.

SUMMARY BACKGROUND DATA

The purpose of this investigation was to apply the delay principle to the gastrointestinal tract, investigate mechanisms by which it occurs and examine the effects of delay on anastomotic healing.

METHODS

Thirty-seven opossums were assigned to Sham (n = 5), Immediate (n = 14), and Delay (n = 18) groups. Each underwent laparotomy and measurement of baseline gastric fundus blood flow. The Delay and Immediate animals underwent ligation of the left, right, and short gastric vessels and subsequent measurement of gastric fundus blood flow. The Delay group underwent repeat measurement of blood flow, esophagogastrectomy, gastric tubularization, and esophagogastrostomy 28 days after vessel ligation. The Immediate group completed the procedure immediately after vessel ligation. The anastomoses in both groups were harvested 32 days after esophagogastrostomy. The Sham group underwent blood flow measurement on initial laparotomy, followed by harvesting of esophagogastric junction 60 days later. Sections taken through the anastomoses were examined with trichrome-staining and immunohistochemistry (IHC) for actin. Collagen content of the gastric submucosa 5 mm below the anastomosis was quantified, and preservation of the muscularis propria and muscularis mucosa was determined histologically. Capillary content of the esophagogastric junction was quantified using IHC for vascular endothelium in the Delay and Sham groups.

RESULTS

Blood flow decreased by 73% following vessel ligation in Delay and Immediate groups. The Delay group had over 3 times the gastric blood flow of the Immediate group at the time of anastomosis at 16 (interquartile range [IQR] 11-17) versus 5, (IQR 5-6) mL/min/100 g (P = 0.000003). Two Immediate animals developed anastomotic leak and died; the Delay group had no complications. Submucosal collagen content in Sham, Delay, and Immediate groups were 57% (IQR 52-62), 65% (IQR 57-72), and 71% (IQR 60-82), respectively (P = 0.0004). The median distance of full-thickness atrophy of the muscularis propria was 0.10 mm (IQR 0-0.60 mm) in the Delay group and 0.53 mm (IQR 0.03-0.80 mm) in the Immediate group (P = 0.346). Five percent of the Delay group had atrophy of the muscularis mucosa, whereas 19% of Immediate animals had atrophy of this layer (P = 0.023). Compared with the Sham group, all Delay animals developed dilation of the right gastroepiploic artery and vein. A median of 27 (IQR 23-33) capillaries per 20x field was observed in the Sham fundus and 38 (IQR 31-46) in the Delay fundus (P = 0.037).

CONCLUSIONS

The delay effect is associated with both vasodilation and angiogenesis and results in increased blood flow to the gastric fundus prior to esophagogastric anastomosis. Animals undergoing delayed operations have less anastomotic collagen deposition and ischemic injury than those undergoing immediate resection. Clinical application of the delay effect in patients undergoing esophagogastrectomy may lead to a decreased incidence of leak and stricture formation.

Octreotide exerts only acute, but no sustained, effects on MRI enhancement of liver metastases in carcinoid syndrome

We have investigated the acute and sustained hemodynamic effects of octreotide on hepatic metastases of midgut carcinoids using contrast-enhanced dynamic magnetic resonance imaging (MRI). Seven patients with the carcinoid syndrome and metastasized midgut carcinoid tumors underwent functional dynamic multi-phase gadolinium-enhanced MRI of selected liver metastases at baseline and 60 min after the subcutaneous (s.c.) administration of 100 microg octreotide, and also after 3 months with three times daily (t.i.d.) 100 microg octreotide s.c. Baseline MRIs showed the typical aspect of carcinoid liver metastases with a very bright signal on the T2-weighted sequences and intense enhancement in the arterial phase after injection of gadolinium-diethylenetriaminepentaacetate. MRIs 60 min after the s.c. administration of 100 microg octreotide showed a 34.9 +/- 6.2% (mean +/- SD) reduction in relative enhancement in the selected liver metastases as compared to baseline. In 2 patients, however, there was no (significant) reduction in the relative enhancement in the selected liver metastases 60 min after the s.c. administration of 100 microg octreotide as compared to baseline. Only in 2 patients did the MRIs at 3 months show a decrease in relative enhancement in one of the selected liver metastases. At 3 months, with 100 microg octreotide s.c. t.i.d., there was no correlation between the change in relative enhancement on MRI and the change in 24-hour 5-HIAA excretion. There is thus only an acute effect of octreotide on the perfusion of liver metastases. This study further shows that contrast-enhanced dynamic MRI can be a very useful tool for studying hemodynamic effects of medical therapies on liver metastases in patients with metastatic midgut carcinoids.

Pharmacological rationale for the use of somatostatin and analogues in portal hypertension

Somatostatin and its analogue octreotide have been used for two decades to treat oesophageal variceal haemorrhage. The drug was introduced because of its capacity to decrease portal venous pressure without major side effects. In clinical trials assessing the efficacy of somatostatin and long-acting analogues in arresting variceal haemorrhage, conflicting results have been obtained. Furthermore, in haemodynamic studies evaluating the effects of somatostatin and analogues in patients with cirrhosis, divergent effects were observed. The main reason for these differences is probably related to different affinities of the drugs for different somatostatin receptor subtypes. The effects of somatostatin and analogues are mediated via five different G-protein coupled receptors (somatostatin receptor subtypes 1-5), which regulate the activity of ion channels (Ca2+, K+, Na+ and Cl-) and enzymes (adenyl cyclase, phospholipase C, phospholipase A2, phosphoinositide 3-kinase and guanylate cyclase) responsible for the synthesis or degradation of intracellular second messengers including cyclic AMP, inositol 1,4,5-trisphosphate, diacylglycerol and cyclic GMP. Despite universal use of somatostatin, the cellular and biochemical mechanisms of its effects in portal hypertension are relatively poorly studied and remain incompletely understood. In this review, we summarize relevant signal transduction of somatostatin and analogues, the haemodynamic effects of the drugs and the possible mechanisms by which these effects are mediated.

A linear-array freehand 3-D endoscopic ultrasound

Recognition of the clinical importance of linear-array endoscopic ultrasound (EUS) has increased. In this study, we developed a linear-array 3-D EUS, a miniature position sensor attached to the tip of the echoendoscope used in freehand scanning. To evaluate the geometrical accuracy of the 3-D reconstruction of the system, the diameter of a sphere-shaped phantom (38 mm) was determined by five examiners and five measurers. Measured size of the sphere was 39.03 +/- 1.29 mm, with variance between examiners and measurers, and interaction of examiners with measurers was not significant. In animal and clinical studies, the system facilitated anatomical interpretation of the EUS images, especially in the pancreatobiliary area and vascular images. We concluded that this system is both accurate and reproducible, and may resolve difficulties in linear-array EUS.

Endoscopic ultrasound and upper gastrointestinal disorders

Endoscopic ultrasound (EUS) plays a vital role in management of upper gastrointestinal disorders, particularly cancer of the esophagus, pancreas, stomach, lung (via transesophageal mediastinal staging), and bile duct. Endoscopic ultrasound has also been valuable in detection of early chronic pancreatitis (CP). In cancer of the esophagus, the primary role of EUS is to determine whether disease is localized (T1-2, N0) and appropriate for surgery, locally advanced (T3-4, N1, M1a) (which may benefit from chemoradiation with or without surgery), or metastatic. Pancreatic and bile duct cancers are more complex given the controversy over portal vein resection. In centers that resect tumors invading the portal venous system, the role of EUS is limited to tissue confirmation or identification of metastases to the liver or distant lymph nodes. In centers that do not resect the portal vein invasion, EUS plays an important role in local staging. In lung cancer, EUS is emerging as an accurate, nonsurgical alternative to staging the mediastinum through EUS fine-needle aspiration. Endoscopic ultrasound has an important role in diagnosing CP because of its high degree of sensitivity. This has also led to controversy over whether EUS can overdiagnose CP. For these reasons, we recommend the use of a high threshold for EUS and that CP be diagnosed in conjunction with other standard tests (endoscopic retrograde cholangiopancreatography, pancreatic function tests).