Daily variation in portal blood flow and the effect of propranolol administration in a randomized study of patients with cirrhosis

Role of circadian rhythm and autonomic nervous system in liver function: a hypothetical basis for improving the management of hepatic encephalopathy

Hepatic encephalopathy (HE) is a common, incapacitating complication of cirrhosis that affects many patients with cirrhosis. Although several therapies have proven effective in the treatment and prevention of this condition, several patients continue to suffer from covert disease or episodes of relapse. The circadian rhythm has been demonstrated to be pivotal for many body functions, including those of the liver. Here, we explore the impact of circadian rhythm-dependent signaling on the liver and discuss the evidence of its impact on liver pathology and metabolism. We describe the various pathways through which circadian influences are mediated. Finally, we introduce a novel method for improving patient response to drugs aimed at treating HE by utilizing the circadian rhythm. A digital system that introduces a customization-based technique for improving the response to therapies is presented as a hypothetical approach for improving the effectiveness of current medications used for the treatment of recurrent and persistent hepatic encephalopathy.

Low air temperature increases the risk of oesophageal variceal bleeding: a population and hospital-based case-crossover study in Taiwan

BACKGROUND & AIMS

Studies concerning seasonal variations and the impact of air temperature on oesophageal variceal bleeding have yielded conflicting results. We aimed to explore the impact of air temperature on the occurrence of variceal bleeding.

METHODS

A case-crossover study design was employed, and two cohorts were used, including the NHI-EVB cohort from the National Health Insurance Research Database of Taiwan from 1 January 1999 to 31 December 2010, and the VGH-EVB cohort from the Taipei Veterans General Hospital, from 4 May 2002 to 31 December 2010. A conditional logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

In total, 2542 cases from the NHI-EVB cohort and 220 cases from the VGH-EVB cohort were analysed. Our analysis showed that low air temperature (LAT) increased the risk of variceal bleeding regardless of age, sex, decompensated cirrhosis, Child-Pugh classification, aetiology of liver disease and concomitant hepatocellular carcinoma; the lag effect was also observed. The ORs per 5°C decrease in daily mean air temperature were 1.144 (95% CI, 1.060-1.235) for the NHI-EVB cohort and 1.307 (95% CI: 1.031-1.658) for the VGH-EVB cohort. Oesophageal variceal bleeding in patients with small varices, end-stage liver disease score ≧15 or those using non-selective beta blockers was not influenced by air temperature.

CONCLUSIONS

Patients have higher risk of oesophageal variceal bleeding at low air temperature regardless of age, sex, aetiology of cirrhosis, Child-Pugh classification, decompensated cirrhosis and concomitant hepatocellular carcinoma and can be protected by use non-selective beta blockers.

Impaired regulation of portal venous flow in response to a meal challenge as quantified by 4D flow MRI

PURPOSE

Portal and mesenteric hemodynamics is greatly altered in portal hypertension patients. This study utilizes 4D flow magnetic resonance imaging (MRI) to visualize and quantify changes in abdominal hemodynamics in patients with portal hypertension undergoing meal challenge.

MATERIALS AND METHODS

Twelve portal hypertension patients and six healthy subjects participated in the study. Baseline MRI was acquired after 5 hours of fasting. Postmeal MRI was obtained 20 minutes after subjects ingested EnSure Plus (574 mL). Imaging was performed at 3T using 4D flow MRI with an undersampled radial acquisition. Flow measurements were performed blinded to subject status (fasting/meal). Flow values for each vessel were compared before and after the meal challenge using paired Student's t-tests (P < 0.05).

RESULTS

After meal challenge, significant increases in blood flow were observed in supraceliac aorta, portal vein, superior mesenteric vein, and artery in both groups (P < 0.05). In patients, hepatic artery (P = 0.001) and splenic vein (P = 0.045) flow decreased while azygos vein flow (P = 0.002) increased.

CONCLUSION

Portal venous flow regulation to adjust the increasing mesenteric venous flow after a meal challenge may be impaired in patients with cirrhosis. The ability to comprehensively quantify the hemodynamic response of the abdominal vasculature to a meal challenge using 4D flow MRI reveals the potential of this technique to noninvasively characterize portal hypertension hemodynamics.

Meal ingestion markedly increases liver stiffness suggesting the need for liver stiffness determination in fasting conditions

INTRODUCTION

The introduction of noninvasive liver stiffness (LS) determination has heralded a new stage in the diagnosis and treatment of liver fibrosis.

AIM

We evaluated the effect of food intake on LS in patients with different degrees of liver disease.

PATIENTS AND METHODS

We evaluated 24 patients (F≤1, n=11 and F> 1, n=13). LS (Fibroscan®) and portal blood flow (PBF) (Doppler ultrasound) were studied before and 30min after ingestion of a standard liquid meal.

RESULTS

Food intake increased PBF (51±10%, p<0.001). Splanchnic hyperemia was accompanied by a significant rise in LS (from 7.8±3.3 to 10.3±4.1kPa, p<0.001). These increases were similar in patients with minimal fibrosis(F≤1) and in those with more advanced fibrosis or cirrhosis (F>1). Hemodynamic and LS values returned to baseline pre-meal levels within 2hours.

CONCLUSION

LS increases markedly after ingestion of a standard meal, irrespective of the degree of fibrosis. Our results strongly suggest that LS should be measured in fasting conditions.

Chronopharmacokinetics of drugs in toxicological aspects: A short review for pharmacy practitioners

A rough 24-hour cycle driven endogenously in biochemical, physiological or behavioral processes is called circadian rhythm. Chronobiology is the study of biological temporal rhythms. For decades, we know that the biological rhythm and the drug metabolism are also affected from daylight and chronopharmacology became recognized by scientists in the early 1970s. Its lateral branch chronocopharmacokinetics is the study of rhythmic, predictable-in-time differences in the pharmacokinetics of drugs. Chronopharmacokinetic studies are performed at every step of the biotransformation i.e., absorption, distribution, metabolism and excretion. Feeding schedules, sex and phenotype must be taken into consideration while applying pharmacotherapy to increase the efficiency and to decrease side effects. The impact of drugs on circadian rhythm should be not neglected. On the other hand, new special drug delivery systems can be used to synchronize drug concentrations according to circadian rhythms. “Chronopharmaceuticals” can identify the proper dosing time and this amelioration will lead to improved progress and diffusion of pharmacotherapy. Chronopharmaceuticals coupled with nanotechnology could be the future of drug delivery systems, and lead to safer and more efficient disease therapy in the future. In this review, we will discuss the pharmacokinetic effects of circadian rhythm and its toxicological outcomes. Besides, we will try to give some practical points for clinical pharmacist/pharmacy practitioners, concerning chronopharmacokinetics.

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.

Circadian pattern of acute variceal bleeding among cirrhotic Egyptian patients

BACKGROUND

Liver cirrhosis is the most common cause of portal hypertension which may end in serious bleeding from gastro-esophageal varices. Recent studies have demonstrated a daily pattern of acute upper gastrointestinal bleeding in patients with liver cirrhosis evidenced by one or two peaks throughout the day.

AIM

The assessment of the circadian rhythm of acute variceal bleeding with the possible participation of circadian changes of the fibrinolytic parameters.

PATIENTS AND METHODS

The study included 264 patients with liver cirrhosis and upper gastrointestinal bleeding in addition to 20 healthy subjects as a control group. A series of hemostatic tests and parameters including prothrombin (PT), activated partial thromboplastin time (APTT), fibrinogen (Fib), Factors II, V, VII, IX, X, XI, platelets counts and fibrinolytic parameters assessement were completed in 60 patients in addition to the control group. The fibrinolytic activity was assessed by estimation of plasminogen, tissue plasminogen activator antigen (tPA: Ag) and plasminogen activator inhibitor antigen (PAI-1: Ag) at hour 09:00 and hour 17:00. The hemostatic tests and liver function tests were assessed once at hour 09.00.

RESULTS

We observed statistically significant two time peaks of upper gastrointestinal bleeding at hour 04:00 and hour 17:00 with a peak of the fibrinolytic parameter, tissue plasminogen activator antigen, with the night peak of bleeding. A significant correlation between the levels of fibrinolytic parameters and hemostatic factors as well as liver function tests were detected.

CONCLUSION

There are two time peaks of upper gastrointestinal bleeding with a temporal association between the night peak and a relative hyperfibrinolytic state.

Circadian rhythm of fasting and postprandial portal blood flow in cirrhosis

OBJECTIVE

To examine the relationship of both the unstimulated and the postprandial portal blood flow (PVF) to the time of day and to determine its intra-individual reproducibility over time in patients with liver cirrhosis.

MATERIAL AND METHODS

In 24 cirrhotic patients, 27 PVF measurements were performed during 24 h on day 0 and day 7 using Doppler ultrasound. Three standard liquid meals were given orally. On day 7, the baseline hepatic venous pressure gradient (HVPG) was also measured.

RESULTS

Circadian area under the time curve of PVF was highly reproducible within individuals (r=0.959, p<0.001). It did not correlate with HVPG. Cosinor analysis showed a significant circadian rhythm of PVF (acrophase at 11:44 and amplitude of 9.44%). Maximal postprandial increase in PVF was significantly higher in the morning than at noon or in the evening.

CONCLUSIONS

PVF is subject to a circadian rhythm and postprandial portal hyperemia shows a diurnal variability. Both are highly reproducible.

Effect of propranolol and depot lanreotide SR on postprandial and circadian portal haemodynamics in cirrhosis

BACKGROUND

Long-acting somatostatin analogues have been suggested as an alternative to propranolol for the prevention of variceal rebleeding.

AIM

To compare the effectiveness of lanreotide SR, a new depot formulation injected once-weekly, and propranolol in reducing circadian portal blood flow (PVF) and meal-stimulated hepatic venous pressure gradient (HVPG) in patients with liver cirrhosis.

METHODS

Patients were randomized to receive either lanreotide SR intramuscularly (30 mg once weekly, n=12) or propranolol (n=12) orally. Hemodynamic measurements were performed on day 0 and on day 21 after a 3-week period of drug administration, while patients received three standard oral liquid test meals. On each study day 27 PVF measurements were performed over 24 h and eight measurements of HVPG during the first postprandial period.

RESULTS

Propranolol was more effective than lanreotide SR in reducing baseline HVPG (-21.9 vs. -13.6%, P=0.04) and meal-stimulated HVPG (-16.6 vs. -3.8%, P=0.04). Propranolol reduced circadian PVF significantly by 9.3% (P=0.03) but not lanreotide SR.

CONCLUSIONS

Long-term treatment with propranolol reduced baseline and postprandial HVPG and circadian PVF, while lanreotide SR did not. The results of our study do not encourage clinical testing of lanreotide SR 30 mg for the prevention of variceal haemorrhage.

Cardiac output determined by echocardiography in patients with cirrhosis: comparison with the indicator dilution technique

BACKGROUND/AIMS

Measurement of cardiac output in hyperkinetic patients with cirrhosis by Doppler echocardiography is increasingly reported, but has not been validated. We have compared simultaneous measurements of cardiac output by Doppler echocardiography (CO(d)) and by the indicator dilution technique (CO(I)).

METHODS

Twelve patients with cirrhosis were studied. CO(d) was measured as the spatial mean velocity of the left ventricular outflow tract, multiplied by the cross-sectional area and the heart rate. CO(I) was determined by the standard indicator dilution technique after injection of 125I albumin and 99mTc albumin into the right atrium and subsequent sampling from the femoral artery.

RESULTS

The mean CO(d) and CO(I) were similar (7.20 vs 7.15 l/min, NS). A highly significant correlation was present between CO(d) and CO(I) (r = 0.86, P < 0.0001; slope 0.91, Y(0) = 0.78 l/min). However, the mean squared difference between CO(d) and CO(I) was 2.3 (l/min)2. A Bland-Altman plot revealed no trend with the level of cardiac output. The standard deviation (0.79 vs 0.30 l/min, P < 0.01) and the coefficient of variation (10.5 vs 4.2%, P < 0.01) of duplicate measurements were significantly higher with the Doppler technique.

CONCLUSION

Doppler measurements of cardiac output in groups of patients with cirrhosis are accurate with respect to the group mean, but marked disagreements of over- and underestimation were seen in individual patients. The reproducibility of the Doppler technique is acceptable, although not as good as that of the indicator dilution technique.

Effects of long-term propranolol and octreotide on postprandial hemodynamics in cirrhosis: a randomized, controlled trial

BACKGROUND & AIMS

Postprandial increases in portal pressure may influence esophageal variceal rupture. The effects of chronic propranolol and octreotide (100 and 200 microg subcutaneously in a single dose) on postprandial hemodynamics were evaluated.

METHODS

FIRST STUDY: 36 cirrhotic patients were studied at baseline and 30 and 60 minutes after a standard meal and then treated with propranolol (139 +/- 9 mg/d during 39 +/- 2 days). SECOND STUDY: After baseline measurements, patients were randomized into 3 groups: (1) placebo, (2) octreotide (100 microg), or (3) octreotide (200 microg) (n = 12 for each group). Thirty minutes postinjection a new baseline was established and measurements were repeated 30 and 60 minutes after the meal.

RESULTS

First study: Baseline portal pressure was 18.1 +/- 1.2 mm Hg, 30 and 60 minutes after the meal it was 21.5 +/- 0.8 mm Hg and 20.5 +/- 0.8 mm Hg, respectively (both P < 0.01 vs. baseline). Cardiac index (CI) was 4.5 +/- 0.2, 4.8 +/- 0.2, and 4.9 +/- 0.2 L x min(-1) x m(-2), respectively (both P < 0.05 vs. baseline). Peripheral vascular resistance was 1012 +/- 56, 902 +/- 51 (P = NS), and 884 +/- 49 dynes x sec x cm(-5) (P< 0.05 vs. baseline), respectively. Second study: Propranolol and placebo did not blunt postprandial increase in portal pressure. Octreotide (100 microg) partially ameliorated postprandial increase in portal pressure. Octreotide (200 microg) significantly enhanced the portal hypotensive effect of propranolol and blunted the postprandial increase in portal pressure.

CONCLUSIONS

Octreotide blunts postprandial increase in portal pressure not prevented by long-term propranolol administration.

Nitric oxide synthase activity in the splanchnic vasculature of patients with cirrhosis: relationship with hemodynamic disturbances

BACKGROUND/AIMS

It has been demonstrated that an overproduction of nitric oxide plays an important role in the pathogenesis of the hyperdynamic circulation exhibited by cirrhotic patients. Nevertheless, evidence is supported by studies performed in experimental models or by indirect measurements in humans. The purpose of this study has been to evaluate nitric oxide production in splanchnic vasculature of patients with cirrhosis and to investigate its possible relationship with systemic and splanchnic hemodynamics.

METHODS

Nitric oxide synthase (NOS) activity was measured in hepatic artery and portal vein tissues of nine cirrhotic patients. Samples were obtained during liver transplantation. Control samples were obtained simultaneously from the corresponding tissues of the liver donors. Hemodynamic parameters were determined with Doppler ultrasonography.

RESULTS

NOS activity was significantly higher in hepatic artery of cirrhotic patients than in controls (8.17 +/- 1.30 vs 4.57 +/- 0.61 pmoles/g of tissue/min, P < 0.05). Patients with ascites showed a higher hepatic artery NOS activity than patients without ascites. Highly significant correlation was observed between cardiac output and hepatic artery NOS activity as well as between portal blood flow and hepatic artery NOS activity.

CONCLUSIONS

The present study demonstrates an enhanced production of nitric oxide in the splanchnic vasculature of patients with cirrhosis.

Seasonal variations in variceal bleeding mortality and hospitalization in France

OBJECTIVES

The circadian variation in portal blood pressure and in the diurnal incidence of variceal bleeding is well known, but the seasonal variation in variceal bleeding is still controversial. This report analyzes the seasonal variations in mortality and hospitalizations due to variceal bleeding in the French population.

METHODS

All the deaths due to variceal bleeding that occurred from 1987 to 1996 (N = 13,514) and all adults discharged from French public hospitals for variceal bleeding from 1995 to 1997 (N = 17,026) were examined retrospectively. Cumulated monthly averages were expressed as the percentage above or below the average monthly value during the entire study period.

RESULTS

Deaths due to variceal bleeding in France occurred with a clear annual periodicity and peaked in winter (December/January), both in the overall population and in subgroups defined by age and sex, except for women. The distribution of cumulative monthly deaths differed by 24%, with a peak (14% above average) in December and a trough (10% below average) in July (Roger's test: p < 0.001). Hospitalizations for variceal bleeding in French public hospitals followed a similar seasonal pattern (p < 0.001) with a winter-spring predominance (4% to 7% from December through April), except in patients aged 15-49 yr. There was a short sharp peak of mortality in early winter in French public hospitals. The seasonality of hospitalization and death increased markedly with age.

CONCLUSIONS

A better understanding of these age- and sex-specific seasonal patterns would allow to improve pharmacological protection measures, disease management, and educational strategies.

Portal hypertension

Many advances in the management of portal hypertension and variceal hemorrhage have occurred during the last 10 years. Effective therapy for primary prevention of variceal hemorrhage is now available in the form of nonselective beta-blockers. Active bleeding should be managed with terlipressin, somatostatin or its analogues, and endoscopic therapy; TIPS and surgery are reserved as salvage therapy for patients who fail endoscopic treatment. Survivors of a variceal hemorrhage should be evaluated for liver transplantation. Specific treatment may be provided with EVL while these patients await transplantation. Patients who fail endoscopic treatment may be treated by TIPS or surgery.

Daily variation of azygos and portal blood flow and the effect of propranolol administration once an evening in cirrhotics

BACKGROUND/AIMS

Esophageal variceal bleeding occur more often at night, however, the mechanism for this remains unclear. This study investigated the daily variation of azygos blood flow (AzBF) and portal blood flow (PBF) and the effects of propranolol administration given once in evening in cirrhotics.

METHODS

Blood flow were measured using magnetic resonance imaging. Hemodynamic parameters were determined at 08:00, 16:00 24:00 and again 08:00 h, and were measured at baseline and after 14 days oral administration of propranolol (30 mg, n = 7) or placebo (n = 7) at 19:00 h in 14 patients.

RESULTS

A daily fluctuation of AzBF and PBF was observed, peaking at 24:00 h in nine patients. In three other patients, peak AzBF and PBF were observed both at 16:00 and 24:00 h. Two patients were constant throughout the day. When the daily variation was compared, ANOVA showed a significant difference (P < 0.001). Propranolol administration at 19:00 h reduced AzBF (-40.7 +/- 17.9% vs. baseline, P < 0.001) and PBF (-26.5 +/- 10.7% vs. baseline, P < 0.01) at 24:00 h.

CONCLUSIONS

We found that in most cirrhotics, AzBF and PBF peaks at midnight. Dosing of propranolol in the evening may be important for its role in preventing variceal bleeding.

Nitric oxide may contribute to nocturnal hemodynamic changes in cirrhotic patients

OBJECTIVE

Patients with liver cirrhosis have a nocturnal worsening of hemodynamic parameters that has been associated with an increased risk of variceal bleeding at nighttime. The aim of this study was to investigate whether nitric oxide and cytokines are implicated in these hemodynamic changes.

METHODS

Ten cirrhotic patients and eight controls were studied. Mean blood pressure, heart rate, plasma norepinephrine, tumor necrosis factor alpha and interleukin-6 levels, and serum nitrite + nitrate levels were determined at 0800, 1600, and 2400 h. All determinations were performed in supine rest and at least 4 h after meals. In a second study, nitrite + nitrate levels were assessed in 10 cirrhotic patients before and after eating a standard meal.

RESULTS

Mean arterial pressure levels that were always lower in the patient group showed a nocturnal decrease in both groups of subjects. Heart rate values that were always higher in cirrhotic patients showed a nocturnal fall in controls, whereas cirrhotics maintained elevated values at nighttime. Norepinephrine levels were higher in cirrhotics and maintained similar values during the study, whereas controls had a significant nocturnal decrease. Nitrite + nitrate levels that were higher in cirrhotic patients showed a significant mean increase of 40% from morning (0800 h) to night (2400 h) in the patient group, whereas in controls no change was observed (p < 0.05). Tumor necrosis factor alpha and interleukin-6 levels did not change either in patients or controls during the entire period. Cirrhotic patients with or without ascites maintained a pattern of hemodynamic and biochemical changes similar to the pattern observed in the entire group of patients. Finally, no changes in serum nitrite + nitrate levels were observed in patients before and after eating the standard meal.

CONCLUSION

An increased nocturnal nitric oxide production might contribute to the hemodynamic changes observed in cirrhotic patients during nighttime.

Doppler evaluation of the effects of pharmacological treatment of portal hypertension

The splanchnic pharmacodynamic effects of the drugs used for the treatment of hemorrhagic complications of portal hypertension were poorly clarified until some years ago. The introduction of Doppler ultrasound provided a powerful tool to investigate such hemodynamic effects and brought new insights in this field. The present article reviews the pharmacodynamics of the substances used in the treatment of portal hypertension, with particular regard to the effects assessable by duplex Doppler ultrasonography.

Effects of propranolol on the hepatic hemodynamic response to physical exercise in patients with cirrhosis

Physical exercise increases portal pressure (hepatic venous pressure gradient [HVPG]) in patients with cirrhosis. It is unknown if this deleterious effect is associated with changes in gastroesophageal collateral blood flow and if these can be prevented by propranolol administration. The aim of this study was to characterize the effects of propranolol on the splanchnic hemodynamic response to exercise in patients with cirrhosis. Twenty-three patients with cirrhosis and portal hypertension had hemodynamic measurements in baseline conditions, and during moderate cycling exercise (40 W) under double-blind propranolol or placebo administration. In patients receiving placebo, HVPG significantly increased during exercise (from 16.7 +/- 0.9 to 19.0 +/- 1.0 mm Hg; P < .01), hepatic blood flow (HBF) decreased (-18% +/- 4%; P < .01), while azygos blood flow (AzBF) was unchanged (4% +/- 12%; ns). In patients receiving propranolol, portal pressure did not increase during exercise, but decreased from 16.3 +/- 1.0 to 12.9 +/- 1.1 mm Hg (P < .01). The lack of increase in HVPG in response to exercise in patients receiving propranolol may be related to a more pronounced decrease in HBF, as compared with patients receiving placebo, and to a blunted increase in cardiac output (CO). Moderate physical exercise adversely influences the hepatic hemodynamics in patients with cirrhosis, causing a significant increase in portal pressure. This is effectively prevented by propranolol pretreatment.