Acute changes in cerebral blood flow and metabolism during portasystemic shunting

Pathological Features of Mitochondrial Ultrastructure Predict Susceptibility to Post-TIPS Hepatic Encephalopathy

BACKGROUND

Post-TIPS hepatic encephalopathy (PSE) is a complex process involving numerous risk factors; the root cause is unclear, but an elevation of blood ammonia due to portosystemic shunt and metabolic disorders in hepatocytes has been proposed as an important risk factor.

AIMS

The aim of this study was to investigate the impact of pathological features of mitochondrial ultrastructure on PSE via transjugular liver biopsy at TIPS implantation.

METHODS

We evaluated the pathological damage of mitochondrial ultrastructure on recruited patients by the Flameng classification system. A score ≤2 (no or low damage) was defined as group A, and a score >2 (high damage level) was defined as group B; routine follow-up was required at 1 and 2 years; the incidence of PSE and multiple clinical data were recorded.

RESULTS

A total of 78 cases in group A and 42 in group B completed the study. The incidence of PSE after 1 and 2 years in group B (35.7% and 45.2%, respectively) was significantly higher than that in group A (16.7% and 24.4%, respectively); the 1- and 2-year OR (95% CI) were 2.778 (1.166-6.615) and 2.565 (1.155-5.696), respectively, for groups A and B. Importantly, group B had worse incidence of PSE than group A [P=0.014, hazard ratio (95%CI): 2.172 (1.190-4.678)].

CONCLUSION

Aggressive damage to mitochondrial ultrastructure in liver shunt predicts susceptibility to PSE. The registration number is NCT02540382.

Cirrhotic Multiorgan Syndrome

Patients with cirrhosis and portal hypertension are at an increased risk of the development of circulatory dysfunction that may potentially result in multiple organ failure. Apart from the liver, this may involve the heart, lungs, kidneys, the immune system, the adrenal glands, and other organ systems. As the disease progresses, the circulation becomes hyperdynamic, and signs of cardiac, pulmonary, and renal dysfunction are observed, in addition to reduced survival. Infections and an altered cardiac function known as cirrhotic cardiomyopathy may be precipitators for the development of other complications such as hepatorenal syndrome. In patients with chronic organ dysfunction, various precipitating events may induce an acute-on-chronic renal failure and acute-on-chronic liver failure that negatively affect the prognosis. Future research on the pathophysiologic mechanisms of the complications and the precipitating factors is essential to understand the basics of the treatment of these challenging conditions. The aim of the present review is to focus on the development and precipitating factors of various organ failures in patients with decompensated cirrhosis.

Complications of cirrhosis. A 50 years flashback

In patients with cirrhosis and portal hypertension, it is largely the frequency and severity of complications relating to the diseased liver, degree of portal hypertension and hemodynamic derangement that determine the prognosis. It can be considered as a multiple organ failure that apart from the liver involves the heart, lungs, kidneys, the immune systems and other organ systems. Progressive fibrosis of the liver and subsequent metabolic impairment leads to a systemic and splanchnic arteriolar vasodilatation. With the progression of the disease development of portal hypertension leads to formation of esophageal varices and ascites. The circulation becomes hyperdynamic with cardiac, pulmonary as well as renal consequences for dysfunction and reduced survival. Infections and a changed cardiac function known as cirrhotic cardiomyopathy may be involved in further aggravation of other complications such as renal failure precipitating the hepatorenal syndrome. Patients with end-stage liver disease and related complications as for example the hepatopulmonary syndrome can only radically be treated by liver transplantation.

Transjugular intrahepatic portosystemic shunt induced short- and long-term cerebral blood flow variations in cirrhotic patients: an arterial spin labeling MRI study

Short- and long-term effects of transjugular intrahepatic portosystemic shunt (TIPS) on cerebral blood flow (CBF) in patients with cirrhosis are still unclear. The purpose of this longitudinal study was to explore CBF alteration patterns in cirrhotic patients after TIPS. Thirteen cirrhotic patients (7 male, 6 female, mean age 50.0 ± 9.3 years) underwent arterial-spin labeling (ASL) MRI 1-9 days (median 1 days) before TIPS. Follow-up MR examinations were performed about 1 week (median 6 days), 3 months (n = 6), 6-9 months (n = 5) and 12-18 months (n = 5) after TIPS. CBF, ammonia level, Child-Pugh score, number connection test type A (NCT-A) and digit symbol test (DST) scores were converted into relative values by dividing by his/her pre-TIPS values, and then, compared via one-way analysis of variance (ANOVA). Correlations between the pre- and post-TIPS changes of relative CBF (rCBF) and the changes of relative ammonia (rAmmonia), Child-Pugh (rChild-Pugh), and NCT-A/DST (rNCT-A/rDST) scores were calculated by crossing subjects. Compared with the pre-TIPS level, the global rCBF slightly increased by 10.9 % about 1 week later, then rapidly decreased by 14.2 % 3 months later, and flatly decreased by 17.2 % in 6-9 months and 18.0 % in 12-18 months following TIPS. The changes of 3-month rDST score were slightly correlated with 3-month rCBF rather than 1-week rCBF, (P < 0.1, FDR-corrected) No difference was found between the pre- and post-TIPS rAmmonia levels, rChild-Pugh and rNCT-A/rDST scores (Post-hoc P > 0.05). CBF measured at different time points after TIPS insertion showed different patterns, indicating varying longitudinal effects of TIPS on CBF. A sharp decline of rCBF was found in the 1 week to 3 months period after insertion, indicating that high event rate of hepatic encephalopathy might relate with the unadaptable CBF in patients undergoing TIPS insertion.

Transjugular intrahepatic portosystemic shunt does not alter cerebral blood flow

BACKGROUND & AIMS

Cirrhosis patients with symptomatic portal hypertension might be effectively treated with a transjugular intrahepatic portosystemic shunt stent (TIPS). The intervention, however, carries a risk of debilitating portosystemic hepatic encephalopathy (HE). HE in cirrhosis might be associated with decreased cerebral blood flow (CBF), and CBF might decrease after TIPS.

METHODS

We measured CBF by [(15)O]-water positron emission tomography (PET) in 9 nonencephalopathic cirrhosis patients before and median 11 days after the insertion of TIPS. The PET images were co-registered to magnetic resonance images for region-based analysis.

RESULTS

Pre-TIPS whole-brain CBF varied markedly from very low to high-normal values of 0.28-0.58 mL blood/mL of brain tissue/min. There were no systematic changes in whole-brain or regional CBF after the TIPS treatment (P > .1). No patient had HE after TIPS.

CONCLUSIONS

Treating portal hypertension by TIPS in patients with advanced cirrhosis and without HE had no effect on their CBF and seemed not to entail a risk of cerebral hypoperfusion.

Pathogenesis of hepatic encephalopathy and its prevention after transjugular intrahepatic portosystemic shunt

With the increasing use of transjugular intrahepatic portosystemic shunt (TIPS), we have obtained a breakout progress in the therapy of acute esophageal and gastric-fundus variceal bleeding and refractory ascites. whereas the patency of stent and hepatic encephalopathy (or namely portal-systemic encephalopathy, PSE) after TIPS become two great problems for TIPS. The patency of stent has been improved greatly after the use of covered stent such as Viator stents or covered vascular stents. But the problem of hepatic encephalopathy has not been well solved. In this review, we try to explore the pathogenesis of hepatic encephalopathy and its prevention after TIPS.

Brain cytokine flux in acute liver failure and its relationship with intracranial hypertension

BACKGROUND

In acute liver failure (ALF), it is unclear whether the systemic inflammatory response associated with intracranial hypertension is related to brain cytokine production.

AIM

To determine the relationship of brain cytokine production with severity of intracranial hypertension in ALF patients.

METHOD

We studied 16 patients with ALF. All patients were mechanically ventilated and cerebral blood flow measured using the Kety-Schmidt technique and intracranial pressure (ICP) measured with a Camino subdural catheter. We sampled blood from an artery and a reverse jugular catheter to measure proinflammatory cytokines (TNF-alpha, IL-6 and IL-1beta) and ammonia. Additionally, in 3 patients, serial samples were obtained over a 72 h period.

RESULTS

In ALF patients a good correlation between arterial pro-inflammatory cytokines and ICP (r (2) = 0.34, 0.50 and 0.52; for IL-6, IL-1beta and TNF-alpha respectively) was observed. There was a positive cerebral cytokine 'flux' (production), in ALF patients with uncontrolled ICP. Plasma ammonia between groups was not statistically significant. In the ALF patients studied longitudinally, brain proinflammatory cytokine production was associated with uncontrolled ICP.

CONCLUSION

Our results provide novel data supporting brain production of cytokines in patients with uncontrolled intracranial hypertension indicating activation of the inflammatory cascade in the brain. Also, the appearance of these cytokines in the jugular bulb catheter may indicate a compromised blood brain barrier at this late stage.

Transjugular intrahepatic portosystemic stent-shunt: technical factors and new developments

The introduction of expandable metal stents in the mid 1980s led to the development of transjugular intrahepatic portosystemic stent-shunt (TIPSS) as we know it today. Short-lived detrimental effects on the hyperdynamic circulation in cirrhosis accompany the acute reduction in portal pressure following TIPSS creation. Caution is needed in patients with cardiac dysfunction or pulmonary hypertension. With increasing expertise and careful patient selection, fatal procedural complications are rare and TIPSS can even be safely used as a bridge to liver transplantation. Shunt insufficiency and hepatic encephalopathy are more common following TIPSS. Currently, however, novel approaches to tackling both these limitations exist. These include the combination of uncovered TIPSS with variceal band ligation, and the introduction of polytetrafluoroethylene covered stents. Despite the lack of controlled studies, covered stents are now widely used and have the potential to drastically reduce shunt insufficiency, the need for long-term shunt surveillance and even hepatic encephalopathy.

Kidney plays a major role in ammonia homeostasis after portasystemic shunting in patients with cirrhosis

The kidney plays an important role in ammonia metabolism. In this study the hypothesis was tested that the kidney can acutely diminish ammonia release after portacaval shunting. Thirteen patients with cirrhosis (6 female/7 male, age 54.4 +/- 3.3 yr) were studied. Blood was sampled prior to and 1 h after transjugular intrahepatic stent-shunt (TIPSS) insertion from the portal vein, a hepatic vein, the right renal vein, and the femoral vein, and renal and liver plasma flow were measured. Prior to TIPSS, renal ammonia release was significantly higher than ammonia release from the splanchnic region, which was not significantly different from zero. TIPSS insertion did not change arterial ammonia concentration or ammonia release from the splanchnic region but reduced renal ammonia release into the circulation (P < 0.05) to values that were not different from zero. TIPSS resulted in a tendency toward increased venous-arterial ammonia concentration differences across leg muscle. Post-TIPSS ammonia efflux via portasystemic shunts was estimated to be seven times higher than renal efflux. Kidneys have the ability to acutely diminish systemic ammonia release after portacaval shunting. Diminished renal ammonia release and enhanced muscle ammonia uptake are important mechanisms by which the cirrhotic patient maintains ammonia homeostasis after portasystemic shunting.

Effects of porta-systemic shunting and ammonia infusion on cerebral blood flow autoregulation in the rat

BACKGROUND

Portacaval shunting of blood, hyperammonemia, and impaired cerebral blood flow (CBF) autoregulation are assumed to be involved in the development of high intracranial pressure (ICP) in liver failure. In this study, we determined whether CBF autoregulation is impaired by portacaval anastomosis and hyperammonemia.

METHODS

Four groups of pentobarbital-sedated and mechanically ventilated rats were investigated after construction of a portacaval anastomosis or following sham operation. Half of the rats received either infusion of ammonia (55 micromol/kg/minute) or saline for 180 minutes. Arterial pressure and ICP was monitored, and lower limit of CBF autoregulation was determined.

RESULTS

Lower limit of autoregulation was preserved in all four groups of studied animals; vehicle lower limits were 40 +/- 2.3, 40 +/- 2, 54 +/- 1, and 51 +/- 3 mmHg in sham-operated rats, sham rats receiving ammonia infusion, portacaval anastomosis-vehicle animals, and portacaval anastomosis-hyperammonemia animals, respectively. The lower limit of auto regulation was higher in portacaval anastomosis rats (p = 0.01) compared to the sham- operated rats. Hyperammonemia in portacaval anastomosis rats did not aggravate this.

CONCLUSION

Portacaval anastomosis and hyperammonemia does not impair the lower limit of CBF autoregulation. However, shunting of portal blood to the systemic circulation shifts the lower limit of autoregulation to higher blood pressure values, making the brain more sensitive to episodes of arterial hypotension.

Changes in brain size in hepatic encephalopathy: a coregistered MRI study

Magnetic resonance imaging (MRI) coregistration techniques can be used to track changes in brain volume. We aimed to determine whether treatment in chronic liver disease altered brain size. The study group comprised nine patients with cirrhosis (7 Child's grade B and 2 Child's grade C). Six had minimal and three had overt hepatic encephalopathy on clinical, psychometric, and electrophysiological testing. Cerebral MRI was performed in seven patients before and 6 weeks after starting lactulose. A further two patients underwent transjugular intrahepatic portosystemic stent shunting with MRI performed before and 24 h afterwards. One patient had a further scan 3 months after TIPSS. Brain size was measured using a semiautomated contour/thresholding technique. Measurable changes were found after treatment intervention, but there was no correlation with severity of encephalopathy (West Haven criteria) or liver dysfunction (Child's score). Three patients improved on lactulose, the brain size decreased with an increase in ventricular volume. Two patients deteriorated; the brain size increased with a concomitant decrease in ventricular volume. Two stable patients had small changes, one with an increase in brain size and a decrease in ventricular volume and the other showing the converse. Following TIPSS, there was an increase in brain size in both patients, evident within 24 h in one patient and at 3 months in the other. Coregistered MRI demonstrates easily detectable changes in brain size following treatment intervention. Our results support the hypothesis that low-grade brain swelling is present, even in minimal hepatic encephalopathy.

Worsening of cerebral hyperemia by the administration of terlipressin in acute liver failure with severe encephalopathy

There is increasing evidence that terlipressin is useful in patients with cirrhosis and hepatorenal syndrome, but there are no data of its use in patients with acute liver failure (ALF) in whom hepatorenal syndrome is common. Although terlipressin produces systemic vasoconstriction, it produces cerebral vasodilatation and may increase cerebral blood flow (CBF). Increased CBF contributes to intracranial hypertension in patients with ALF. The aim of this study was to evaluate the safety of terlipressin in patients with ALF with respect to cerebral hemodynamics. Six successive patients with ALF were ventilated electively for grade IV hepatic encephalopathy. Patients were monitored invasively and CBF was measured (Kety-Schmidt technique). Measurements were made before and at 1, 3, and 5 hours after intravenous (single bolus) administration of terlipressin (0.005 mg/kg), median, 0.25 mg (range, 0.2-0.3 mg). There was no significant change in heart rate, mean arterial pressure, or cardiac output. CBF and jugular venous oxygen saturation both increased significantly at 1 hour (P = 0.016). Intracranial pressure increased significantly at 1 hour (P = 0.031), returning back to baseline values at 2 hours. In conclusion, administration of terlipressin, at a dose that did not alter systemic hemodynamics, resulted in worsening of cerebral hyperemia and intracranial hypertension in patients with ALF and severe hepatic encephalopathy. These data suggest the need to exercise extreme caution in the use of terlipressin in these patients in view of its potentially deleterious consequences on cerebral hemodynamics.