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Background/aims: Portal hypertension is characterized by the development of a hyperdynamic splanchnic circulation. To determine whether this process is angiogenesis-dependent, we assessed the effects of SU5416, a specific inhibitor of VEGF receptor-2, in portal hypertensive rats., Methods: Rats with portal hypertension induced by partial portal vein ligation were treated with SU5416 or vehicle during 5 days. Then, hemodynamic studies were performed using radioactive microspheres. Protein expressions of CD31, VEGF receptor-2 and VEGF were also determined by Western blotting., Results: Treatment of portal hypertensive rats with SU5416 resulted in a significant and marked decrease (by 44%) in portal venous inflow, and increases in splanchnic arteriolar resistance (by 68%) and portal venous resistance (by 93%). In addition, SU5416 administration significantly inhibited the formation of portal-systemic collateral vessels (52% inhibition), as well as the splanchnic CD31 and VEGF receptor-2 protein expressions in portal hypertensive rats, compared with those receiving vehicle., Conclusions: This study demonstrates that the development of hyperdynamic splanchnic circulation and the formation of portal-systemic collateral vessels in portal hypertensive rats are angiogenesis-dependent processes that can be markedly inhibited by blockade of the VEGF signaling pathway. Therefore, modulation of angiogenesis may represent a potential target in the treatment of portal hypertension.

Background & Aims: Portal hypertension in cirrhosis is secondary to an increase in hepatic resistance that occurs mainly through collagen deposition. However, recent evidence points to a major contribution by other factors, such as an intrahepatic reduction in nitric oxide production. Akt is a major activator of the endothelial nitric oxide synthase (eNOS) enzyme, but its potential role in intrahepatic resistance in cirrhosis is unknown. For this reason the aims of the present study were to determine whether there is an impaired Akt activation in cirrhotic livers and how this phenomenon relates to the decrease in NO production associated with portal hypertension., Methods: Cirrhosis was induced in rats by carbon tetrachloride inhalation. Protein abundance and phosphorylation status of Akt and eNOS were examined by Western blotting. The role of Akt in the liver of cirrhotic rats was investigated through infection with adenoviruses encoding either beta-galactosidase (beta-gal) or constitutively active Akt (myr-Akt)., Results: The liver of cirrhotic animals showed a significant reduction in Akt and eNOS phosphorylation. Adenoviral delivery of myr-Akt restored eNOS phosphorylation and increased the intrahepatic concentration of guanosine 3',5'-cyclic monophosphate. These events were associated with normalization in portal pressure and a significant increase in mean arterial pressure after 3 days of adenoviral infection. In contrast, transduction of livers with beta-gal did not produce any change in these hemodynamic parameters., Conclusions: myr-Akt gene therapy restored Akt activation and NO production in the cirrhotic liver, suggesting that this therapy may be useful for the treatment of portal hypertension.

In cirrhotic patients under pharmacologic treatment for portal hypertension, a reduction in hepatic venous pressure gradient (HVPG) of >or=20% of baseline or to or=20% of baseline or to or=20% or to

Background and Aims: Up to 60% of patients treated with transjugular intrahepatic portosystemic shunt (TIPS) require angioplasty or restenting during the first year of follow up because of TIPS dysfunction (stenosis of the intrahepatic shunt increasing the portal pressure gradient above the 12 mm Hg threshold). We hypothesised that in patients with TIPS stenosis, propranolol administration, by decreasing portal inflow, would markedly decrease portal pressure., Patients and Methods: Eighteen patients with TIPS dysfunction were investigated by measuring portal pressure gradient before and after acute propranolol administration (0.2 mg/kg intravenously; n=18)., Results: Propranolol markedly reduced the portal pressure gradient (from 16.6 (3.5) to 11.9 (4.8) mm Hg; p<0.0001), cardiac index (-26 (7)%), and heart rate (-18 (7)%) (p<0.0001). Portal pressure gradient decreased to less than 12 mm Hg in nine patients, more frequently in those with moderate dysfunction (portal pressure gradient 16 mm Hg) than in patients with severe dysfunction (portal pressure gradient >16 mm Hg) (8/10 v 1/8; p=0.015)., Conclusions: Propranolol therapy may delay the increase in portal pressure and reduce the need for reintervention in patients with TIPS dysfunction.

Many daily activities cause acute elevations of intra-abdominal pressure (IAP). In portal hypertensive cirrhotic patients, increased IAP increases absolute portal pressure and azygos blood flow, suggesting that it may have detrimental consequences at the esophageal varices. The aim of this study was to investigate the effects of increased IAP on variceal pressure, size, and wall tension. Endosonography and a noninvasive endoscopic pressure gauge were used to measure variceal pressure, radius, wall tension, and volume in baseline conditions and after increasing IAP by 10 mm Hg using an inflatable girdle in 14 patients with cirrhosis and esophageal varices. Increasing IAP markedly increased variceal pressure (from 13.3 +/- 4.2 to 17.4 +/- 4.6 mm Hg; P =.0001) and radius (from 2.9 +/- 1.0 to 3.9 +/- 1.1 mm; P =.0001). Consequently, wall tension dramatically increased (from 38.7 +/- 13.6 to 65.9 +/- 23.8 mm Hg. mm, +78%; P =.0001). Variceal volume increased significantly from 1,264 +/- 759 to 2,025 +/- 1,129 mm(3) (P =.0001). In conclusion, in portal hypertensive cirrhotic patients, increases in IAP have deleterious effects on variceal hemodynamics, markedly increasing the volume, pressure, and wall tension of the varices. Increases in IAP may contribute to the progressive dilatation that precedes the rupture of the varices in portal hypertension.

Altered leukocyte/cytokine response to inflammation has been observed in human and experimental portal hypertension. The aim of this study was to characterize leukocyte adhesion in portal hypertensive (PPVL) rats stimulated with endotoxin. Leukocyte rolling, adhesion, and migration assessed by intravital microscopy were impaired in mesenteric venules after lipopolysaccharide administration (150 microg/kg) in PPVL vs. sham-operated rats. Analysis of leukocyte L-selectin expression and soluble L-selectin showed that this defective adhesion was related to increased L-selectin shedding. In vitro experiments using isolated leukocytes treated with phorbol 12-myristate 13-acetate showed that monocytes and neutrophils but not lymphocytes were hyperreactive to cell activation, as measured by CD11b overexpression and increased L-selectin shedding in PPVL rats. However, neutrophil emigration in liver sinusoids and in the lung 3 h after endotoxin injection were similar in both groups of animals. Thus the alterations in leukocyte activation and adhesion molecule expression observed in this study may contribute to a better understanding of the higher susceptibility and severity of bacterial infections in cirrhotic patients with portal hypertension.

The aim of this study was to investigate the influence of different strategies of blood volume restitution in the outcome of portal hypertension-related bleeding in anesthetized cirrhotic rats. Gastrointestinal hemorrhage was induced by sectioning a first order branch of the ileocolic vein in 38 cirrhotic rats (common bile duct ligation and occlusion). The subsequent hypovolemic shock was treated with no transfusion (n = 17), moderate transfusion (50% of expected blood loss, 5 mL, n = 11), and total transfusion (100% of expected blood loss, 10 mL, n = 10). At the end of the blood transfusion period (minute 15), mean arterial pressure (MAP) partially recovered in rats receiving moderate transfusion or no transfusion but decreased in the 10-mL transfusion group ( downward arrow 12 +/- 43%, P < .05 vs. no transfusion and 5 mL transfusion). After transfusion, groups given no or 5 mL transfusion remained hemodynamically stable. However, rats receiving 10 mL transfusion continued to deteriorate with persistent bleeding and progressive fall in MAP ( downward arrow 65 +/- 12%; P < .05 vs. no transfusion and 5 mL transfusion). Collected blood loss was significantly greater in the 10-mL group (20.0 +/- 1.5 g) than in groups given 5 mL (15.9 +/- 2.8 g; P < .05) or no transfusion (13.2 +/- 2.1 g; P < .05 vs. 10 mL and 5 mL transfusion). Survival in the no transfusion group was 47%. Rats given 5-mL transfusion had 64% survival. The worst survival was observed in the 10-mL transfusion group (0% survival; P < .05). We concluded that a transfusion policy aimed at completely replacing blood loss worsens the magnitude of bleeding and mortality from portal hypertensive-related bleeding in cirrhotic rats. On the contrary, moderate blood transfusion allowed hemodynamic stabilization and increased survival.

Background & Aims: Octreotide has been suggested for the treatment of variceal bleeding, but detailed dose-finding studies are not available. We performed a dose-finding study investigating the hemodynamic effects of several forms of intravenous octreotide administration., Methods: Splanchnic hemodynamics and plasma glucagon levels were measured in 68 cirrhotics in baseline conditions and (1) after a double-blind intravenous injection of octreotide (50 microg [n = 9] or 500 microg [n = 8]) or placebo (n = 7); (2) after a 50-microg octreotide bolus followed by continuous infusion of 50 microg/h (n = 8), 250 microg/h (n = 8), or placebo (n = 6); (3) after repeated 50-microg injections of octreotide (n = 9) or placebo (n = 6) after an initial bolus (50 microg octreotide); and (4) after a placebo bolus and continuous octreotide infusion (50 microg/h; n = 7)., Results: Placebo caused no significant changes. Octreotide caused a marked and transient decrease in portal pressure and azygos blood flow and an increase in mean arterial pressure. These effects lasted only 5 minutes despite addition of continuous octreotide infusions. Repeated octreotide injections had shorter, less marked effects than the first bolus. A continuous octreotide infusion did not decrease portal pressure. Glucagon levels were markedly reduced by octreotide, but gradually returned to baseline despite continuous infusions or repeated injections of octreotide., Conclusions: Octreotide injection caused marked but transient reductions in portal pressure and azygos blood flow. Adding a continuous octreotide infusion neither maintained nor prolonged its effects. Repeated boluses caused significant tachyphylaxis. This rapid desensitization to the effects of octreotide may explain the divergent effects achieved with octreotide infusions in acute variceal bleeding.

Noninvasive measurements of variceal pressure adequately reflect the hemodynamic effects of propranolol on portal hypertension. However, the prognostic value of variceal pressure responses during continued propranolol therapy has not been evaluated, and it is unclear whether this may substitute invasive measurements of portal pressure response. Fifty-five portal hypertensive patients with cirrhosis were studied before and at 4 months of continued propranolol therapy. Variceal pressure was measured using an endoscopic pressure gauge. Portal pressure was evaluated as the hepatic venous pressure gradient (HVPG). Over a 28 +/- 11 month follow-up, 16 patients experienced variceal bleeding. Baseline characteristics were similar in bleeders and nonbleeders. At 4 months, reduction in variceal pressure was less marked in bleeders than in nonbleeders (5% +/- 20% vs. -15% +/- 24%; P =.03). A fall in variceal pressure 20% or greater of baseline was an independent predictor of absence of variceal bleeding; which occurred in 5% of patients with a 20% or greater fall in variceal pressure versus 42% of patients with less than a 20% reduction (P =.004). The HVPG response had similar independent prognostic value (decrease > or =20%: 6% bleeding; decrease <20%: 45% bleeding; P =.004) but identified different patients. Achieving a 20% decrease in either variceal pressure or HVPG was highly sensitive (85%) and specific (93%) identifying patients not bleeding on follow-up. Endoscopic measurements of variceal pressure response to continued pharmacotherapy provide useful prognostic information on the risk of variceal bleeding. As with HVPG response, a fall in variceal pressure of 20% or greater is associated with a very low risk of variceal bleeding. The combination of both parameters allows almost optimal prognostication.

Background & Aims: Variceal bleeding is the most important complication of portal hypertension. However, the relationship between the increase in portal pressure and the outcome of variceal bleeding has not been well defined., Methods: We measured the hepatic venous pressure gradient (HVPG) of 65 cirrhotic patients with acute variceal hemorrhage, early after admission (20.6 +/- 15.6 hours)., Results: Twenty-three patients had a poor evolution (failure to control bleeding or early variceal rebleeding), and 42 had an uneventful evolution. The only variable associated with outcome was the HVPG, which was higher in patients with a poor evolution (23.7 +/- 6.1 vs. 19.2 +/- 3.3 mm Hg; P < 0.0004). This was confirmed by multivariate analysis. HVPG was >/=20 mm Hg in 19 of 23 patients with poor evolution vs. 12 of 42 patients with uneventful evolution (P < 0.0001). An initial HVPG of >/=20 mm Hg was associated with a significantly longer intensive care unit stay (7 +/- 5 vs. 4 +/- 2 days; P < 0.02), longer hospital stay (19 +/- 10 vs. 14 +/- 6 days; P < 0.02), greater transfusion requirements (9.0 +/- 7.7 vs. 4.7 +/- 3.2 UU; P < 0.007), and a worse actuarial probability of survival (1-year mortality, 64% vs. 20%; P < 0.002)., Conclusions: Early measurement of HVPG in cirrhotic patients during acute variceal bleeding provides useful prognostic information on the evolution of the bleeding episode and long-term survival.

Background & Aims: Transjugular intrahepatic portosystemic shunt (TIPS) procedures are increasingly being used, but the relationship between the hemodynamic effects of TIPS and the clinical events on follow-up remains undefined. Hence, we have investigated the hemodynamic correlations of portal hypertension-related events after a TIPS procedure., Methods: Prospective follow-up of 122 cirrhotic patients who had a TIPS procedure performed because of variceal hemorrhage was conducted., Results: The portacaval pressure gradient (PPG) significantly decreased after the TIPS procedure (from 19.7 +/- 4.6 to 8.6 +/- 2.7 mm Hg; P > 0.001), but increased thereafter and at rebleeding (n = 25) was > 12 mm Hg in all patients (18.4 +/- 4.6 mm Hg). Twenty-six patients developed ascites; the PPG (measured in 19) was always > 12 mm Hg. Increasing the PPG to > 12 mm Hg occurred very frequently (83% at 1 year). Within 1 year, 77% of patients underwent balloon angioplasty or restenting. However, 80% had again a PPG of > 12 mm Hg 1 year after reintervention. Hepatic encephalopathy developed in 31% of patients at 1 year; 21 of 23 patients had a PPG of < 12 mm Hg., Conclusions: Total protection from the risk of recurrent complications of portal hypertension after a TIPS procedure requires that the PPG be decreased and maintained < 12 mm Hg. However, reintervention will be required in most patients within 1 year and again the second year. On the other hand, such portal decompression is associated with an increased risk of hepatic encephalopathy.

The reintroduction of paracentesis has modified the way in which patients with ascites are treated. Transjugular intrahepatic portosystemic shunt can be an alternative treatment for patients with refractory ascites and for those patients with hepatorenal syndrome, although more studies are needed to clarify its usefulness and safety. The use of more potent and less nephrotoxic antibiotics together with an earlier diagnosis have improved the outcome of patients with spontaneous bacterial peritonitis (SBP). Oral antibiotics can be used in patients with SBP and good clinical conditions with an efficacy similar to that obtained with intravenous antibiotics. Prophylactic antibiotics in SBP should be restricted to cirrhotic patients at high risk, including bleeding cirrhotic patients, those with a past history of SBP, and those with low protein content in ascitic fluid. This chapter describes the management of ascites in patients with portal hypertension.

This retrospective cohort study was aimed at investigating the effects of anemia on the hemodynamic disturbances associated with portal hypertension. In all, 202 consecutive nontreated portal-hypertensive patients referred for evaluation to our Hepatic Hemodynamic Laboratory were included. Compared to the nonanemic patients, anemic cirrhotic patients had an increased cardiac output (7.9 +/- 1.9 vs 7.1 +/- 2 liters/min, P < 0.01), and a decreased mean arterial blood pressure (82 +/- 11 vs 94 +/- 13 mm Hg, P < 0.0001) and systemic vascular resistance (838 +/- 235 vs 1102 +/- 356 dyn/sec/cm5, P < 0.0001). Similar results were obtained when Child A or Child B-C patients were analyzed separately. Multivariate logistic regression disclosed that hemoglobin concentration, in addition to age, sex azygos blood flow, and albumin concentration, was an independent factor influencing the degree of systemic vasodilation in cirrhotic portal-hypertensive patients. This study discloses that anemia worsens the hyperdynamic circulation associated with portal hypertension. Since hemoglobin concentration may change with time, this parameter should be taken into account when evaluating hemodynamics in portal-hypertensive patients.

Background/aims: Terlipressin is a long-acting vasopressin analogue that has been proved useful in the treatment of variceal haemorrhage. This study investigates the time profile of the haemodynamic effects of terlipressin on portal hypertension as well as the efficacy in decreasing portal-pressure and collateral blood flow of reduced doses, suitable for longer therapy to prevent early rebleeding., Methods: Splanchnic and systemic haemodynamics were measured in 23 patients with cirrhosis and portal hypertension in baseline conditions and at 30 min, 1, 2, 3 and/or 4 h after the double-blind administration of a single intravenous injection of 1 mg (n=8) or 2 mg (n=8) of terlipressin, or placebo (n=7)., Results: Placebo caused no significant effects. At 30 min of terlipressin administration, the hepatic venous pressure gradient (1 mg: -16+/-9%, 2 mg: -21+/-11%; p<0.01) and azygos blood flow (1 mg: -19+/-13%, 2 mg: -25+/-17%; p<0.05) were significantly reduced. These effects were still significant at 4 h (2 mg) or 3 h (1 mg). Both doses moderately increased arterial pressure at 1 h. At 4 h, neither arterial pressure nor peripheral vascular resistance was significantly modified by either dose of terlipressin. Terlipressin caused no significant changes in hepatic blood flow., Conclusions: In patients with cirrhosis, a single injection of 2 mg of terlipressin significantly and markedly reduces portal pressure and azygos blood flow for up to 4 h. The effects of a reduced dose (1 mg) were almost as pronounced and prolonged, suggesting that after the initial control of variceal bleeding, terlipressin therapy could be maintained for several days at low dosage to reduce the risk of early rebleeding.

Transjugular intrahepatic portosystemic shunt (TIPS) is a calibrated shunt directed at reducing the portal pressure gradient with a low incidence of hepatic encephalopathy and deterioration of hepatocellular function. The present study investigated the effects of TIPS on splanchnic and systemic hemodynamics on liver function and on the development of encephalopathy. A group of 30 patients treated with TIPS were included in the study: 26 patients with hepatic cirrhosis for an hemorrhagic episode by esophageal varices not controlled by medical treatment and sclerotherapy and in 4 cases with the Budd-Chiari syndrome for ascites refractory to medical treatment. Before, at 24 hours and 2 months after TIPS, the portal pressure gradient, cardiopulmonary pressure and cardiac output, blood flow of the azygos vein, and hepatic clearance of indocyanine green as indexes of liver function were determined. TIPS significantly decreased the portal pressures gradient and azygos blood flow. This was associated with a significant increase in cardiac output and a significant decrease in peripheral vascular resistance and hepatic clearance of indocyanine green. Portal flow deviated by TIPS was greater in the 9 patients (30%) who developed hepatic encephalopathy during follow up. In conclusion, TIPS effectively reduces portal hypertension. Nonetheless, it is associated with an increase in hyperdynamic circulation, a high incidence of encephalopathy and a deterioration in liver function.

Background & Aims: In healthy subjects, exercise promotes marked hemodynamic and humoral changes characterized by an increase in cardiac output, a redistribution of blood flow to muscular territories under activity, and an increase in sympathoadrenergic activity. The aim of this study was to investigate the extent to which hemodynamic and humoral changes caused by exercise may influence portal and systemic hemodynamics in patients with cirrhosis., Methods: In 8 patients with liver cirrhosis and portal hypertension, arterial pressure, cardiac output, portal pressure (as hepatic venous pressure gradient [HVPG]), and hepatic blood flow were measured before and at two steps of cycling exercise equivalent to 30% and 50% of their peak workload., Results: Exercise (at 30% of peak work-load) significantly increased arterial pressure and cardiac output and decreased systemic vascular resistance. This was associated with a significant increase in HVPG (from 16.7 +/- 1.5 to 19.2 +/- 1.6 mm Hg; P < 0.01) and a significant reduction in hepatic blood flow (from 1291 +/- 216 to 1034 +/- 152 mL-min-1; P < 0.05). All of these changes were intensified at 50% of target workload., Conclusions: The present study shows that moderate exercise increases portal pressure and may therefore increase the risk of variceal bleeding in patients with esophageal varices. These findings suggest that cirrhotic patients with portal hypertension should be advised of potential risks during exercise.

Background/aims: It has been suggested that mechanical pumping of portal blood to the liver may correct portal hypertension while increasing portal flow to the liver, which may enhance liver function in cirrhosis. However, the hemodynamic effects of this procedure are unknown. The present study investigated these issues in rats with portal hypertension due to portal vein stenosis., Methods: Mechanical pumping of portal blood to the liver was established by an extracorporeal shunt bypassing the portal vein stenosis, connected to a continuous withdrawal/infusion pump. Portal pressure, portal-systemic shunting (mesenteric injection of Cr-51 microspheres, n = 10), mesenteric artery blood flow (perivascular Transonic flowmeter, n = 7) and systemic hemodynamics and regional blood flows (left ventricle injection of Ce-141 microspheres, n = 15), were measured at pumping rates of 0, 3 and 6 ml.min-1., Results: Mechanical pumping of portal blood to the liver caused a marked decrease in portal pressure (from 17 +/- 1 to 12.6 +/- 1 and 9.4 +/- .9 mmHg at pumping rates of 0, 3 and 6 ml.min-1) and portal-systemic shunting (from 97 +/- 4 to 70 +/- 4 and 51 +/- 6% respectively) (p < 0.001). However, there were no significant changes in mesenteric artery flow (5.5 +/- 3 vs 5.6 +/- 3 ml.min-1.100 g-1), suggesting that all blood pumped to the liver was withdrawn from that circulating through the collaterals. Moreover, there were no changes in mean arterial pressure, cardiac index, peripheral resistance and splanchnic arteriolar resistance., Conclusions: The short-term mechanical pumping of portal blood to the liver effectively decreases portal pressure and portal-systemic shunting and has no significant effects on systemic and splanchnic hemodynamics in portal hypertensive rats.

Background & Aims: Prostacyclin and nitric oxide have been involved in the hyperkinetic syndrome in portal hypertension. The aim of this study was to investigate the relative contribution and possible interaction between prostacyclin and NO in this circulatory abnormality., Methods: Portal vein-ligated and sham-operated rats received indomethacin and vehicle either on a short-term (5 mg/kg subcutaneously) or long-term basis (5 mk.kg-1.day-1, continuous 7-day infusion with an osmotic minipump). Measurements of arterial pressure and superior mesenteric arterial flow (mL.min-1.kg-1, ultrasonic flow probe) were then performed before and after NG-nitro-L-arginine methyl ester (L-NAME) injection (13 mg/kg intravenously)., Results: Short-term or long-term indomethacin treatment had no effect in sham-operated rats but significantly decreased mesenteric arterial flow in portal-hypertensive rats. Mesenteric flow remained higher after long-term than after short-term indomethacin treatment (54.5 +/- 2 vs. 46.1 +/- 2; P = 0.01). This blunted response to long-term indomethacin treatment was associated with an enhanced response to L-NAME, shown by greater increments in arterial pressure (29% +/- 3%) and mesenteric arterial resistance (209 +/- 22%) in indomethacin-treated rats than in rats receiving vehicle (19% +/- 2% and 130% +/- 20%; P < 0.05)., Conclusions: Both prostacyclin and NO contributed to splanchnic hyperemia in portal-hypertensive rats. There was an enhanced release of NO after long-term prostacyclin inhibition, suggesting that both vasodilatory systems interact, promoting splanchnic hyperemia in portal hypertension.

Background & Aims: Nitric oxide, which is quenched by hemoglobin, has been implicated in the pathogenesis of portal hypertension. The aim of this study was to investigate the effects of increasing blood hemoglobin concentration by erythropoietin treatment on the gastrointestinal vasodilation associated with portal hypertension., Methods: Portal-hypertensive and sham-operated rats treated with erythropoietin were studied 2 weeks after surgery. Hemodynamic and rheological parameters were measured in baseline conditions and after N(G)-nitro-L-arginine methyl ester (L-NAME) or sodium nitroprusside treatment., Results: In portal-hypertensive rats, erythropoietin attenuated the increase in gastric mucosal and superior mesenteric artery blood flows and the decrease in arterial blood pressure and splanchnic vascular resistances. Those parameters were not affected by erythropoietin in sham-operated rats. A direct vascular effect of erythropoietin was ruled out by the lack of changes in blood pressure or mesenteric blood flow after intravenous erythropoietin administration and by a similar in vitro relaxation to acetylcholine in mesenteric artery rings. In portal-hypertensive rats, erythropoietin blunted the blood pressure response to sodium nitroprusside and attenuated the gastric and mesenteric blood flow response to L-NAME., Conclusions: Gastrointestinal vasodilation associated with portal hypertension can be attenuated by increasing blood hemoglobin concentration. Inactivation of overproduced NO by hemoglobin may account for this effect.

Background/aims: Effective protection from the risk of variceal bleeding is achieved when the hepatic venous pressure gradient is reduced to 12 mmHg or at least by 20% of baseline values. Such a marked decrease is rarely achieved with propranolol, and new agents or combinations of them are now being explored. The present randomized study investigated whether chronic treatment with the combination of propranolol plus molsidomine, a preferential venous dialator that reduces hepatic venous pressure gradient and does not cause pharmacological tolerance, achieves greater reduction in hepatic venous pressure gradient than propranolol alone., Methods: A hemodynamic study was performed in 34 patients with cirrhosis with portal hypertension in baseline conditions and after 3 months of chronic oral treatment with propranolol alone (n = 19) or propranolol plus molsidomine (n = 15)., Results: Propranolol produced a significant reduction in hepatic venous pressure gradient (-16%, p < 0.01). Propranolol plus molsidomine also caused a slight but significant decrease in hepatic venous pressure gradient (-9%, p < 0.05). Hepatic blood flow and the hepatic and intrinsic clearance of indocyanine green were significantly reduced by propranolol. The combined administration of propranolol+molsidomine significantly reduced hepatic blood flow but not hepatic and intrinsic clearance of indocyanine green. Both treatment groups produced similar reduction in azygos blood flow, heart rate and cardiac output. However, contrary to propranolol alone, propranolol plus molsidomine did not increase cardiopulmonary pressures., Conclusions: The current study shows that although the combined administration of propranolol plus molsidomine prevents some of the adverse effects of propranolol on liver function and cardiopulmonary pressures, it does not achieve a greater reduction in hepatic venous pressure gradient than propranolol alone and therefore, does not support the use of this combined therapy for the pharmacological treatment of portal hypertension.

Background/aims: Excessive nitric oxide biosynthesis caused by expression of inducible NO synthase has been implicated in the hyperdynamic circulation of portal hypertension. The aim of the study was to investigate whether inducible NO synthase is expressed in portal hypertension an accounts for the hyperdynamic circulation., Methods: In study 1, NO synthase activities were measured by the conversion of L-arginine to citrulline in tissues from portal-hypertensive, cirrhotic, and sham-operated rats and from normal rats pretreated with endotoxin and after long-term administration of dexamethasone, which inhibits the expression of inducible NO synthase. In study 2, systemic and splanchnic hemodynamics (radiolabeled microspheres) and gastric blood flow (hydrogen gas clearance and reflectance spectrophotometry) were measured in portal-hypertensive rats after long-term administration of dexamethasone (0.25 mg.kg-1.day-1) or vehicle., Results: In study 1, constitutive and inducible NO synthase activities in portal-hypertensive or cirrhotic rats were similar to those observed in sham-operated rats. The significant increase in the inducible activity observed after endotoxin injection was prevented when rats received long-term treatment with dexamethasone. In study 2, cardiac index, portal-pressure, portal venous inflow, and gastric blood flow were similar in dexamethasone-or vehicle-treated portal-hypertensive rats., Conclusions: These results to not support a role for an increased expression of the inducible NO synthase in the hyperdynamic circulation of portal hypertension.

The present study investigated whether chronic nitric oxide (NO) inhibition prevents the hyperdynamic circulatory syndrome that appears in rats after partial portal vein ligation (PPVL). N omega-nitro-L-arginine methyl ester (L-NAME; 30 micrograms.kg-1.min-1, n = 17), a NO biosynthesis inhibitor, or vehicle (n = 17) was infused continuously from PPVL through subcutaneously osmotic pumps. Studies were performed, in ketamine-anesthetized Sprague-Dawley rats, in one-half of the animals at 4 days and in the remaining one-half at 8 days from PPVL. At 4 days, PPVL rats treated with L-NAME had higher mean arterial pressure (MAP), systemic vascular resistance (SVR), and splanchnic arteriolar resistance (SAR) and lower cardiac output and portal venous inflow (PVI) than PPVL rats treated with vehicle (P < 0.05). Similarly, at 8 days PPVL rats treated with L-NAME had higher MAP and SVR and lower cardiac output (P < 0.05) than PPVL rats treated with vehicle. In contrast, PVI and SAR were similar. At 4 days plasma volume and mesenteric-systemic shunting were lower, although nonsignificantly, in PPVL rats treated with L-NAME. This trend completely disappeared at 8 days. L-NAME did not change portal pressure at either 4 or 8 days. After 4 days of continuous treatment with L-NAME, nonportal hypertensive control rats had a significantly higher MAP, lower cardiac index and PVI, and higher SVR and SAR than nonportal hypertensive rats treated with vehicle. Contrary to PPVL rats, these effects were maintained after 8 days of treatment. The present study shows that NO contributes to the systemic disturbances of portal hypertension. However, NO inhibition delayed but did not prevent the splanchnic vasodilation that appears after PPVL, suggesting that other factors could also be involved.

It has been suggested that estrogen-progestagen therapy may be useful in preventing bleeding from gastric angiodysplasia, a vascular lesion similar to that described in portal-hypertensive gastropathy. In this study we assessed the effects of estrogen-progestagen therapy on gastric microcirculation and systemic and splanchnic hemodynamics in portal-hypertensive and sham-operated rats. One week after the surgical procedure (partial portal vein ligation or sham surgery), animals were given an intramuscular injection of a slow-release preparation of estrogen-progestagen or its vehicle. Two weeks later, gastric mucosal blood flow was measured by means of hydrogen gas clearance, a morphometrical analysis of gastric mucosal blood vessels was performed and systemic and splanchnic hemodynamics were evaluated with a radiolabeled-microspheres technique. In portal-hypertensive rats, estrogen-progestagen therapy induced a significant reduction in gastric mucosal blood flow, number of blood vessels and relative area of vessels. Similar changes, although of lesser magnitude, were achieved with estrogen or progestagen given separately and with the low dose of combined estrogen-progestagen. Estrogen-progestagen treatment also induced significant reductions in portal pressure and porto-collateral resistance without changing systemic or splanchnic hemodynamics. In contrast, estrogen-progestagen treatment did not induce changes in any of the parameters studied in sham-operated rats. We conclude that long-term estrogen-progestagen therapy reduces the gastric hyperemia, increased mucosal vessel density and portal pressure in portal-hypertensive rats.

Gastric perfusion has been found to be increased in cirrhotic patients with portal-hypertensive gastropathy. This phenomenon may contribute to gastric bleeding from these lesions. Therefore drugs reducing gastric mucosal perfusion may be beneficial in the treatment of bleeding portal-hypertensive gastropathy. In this study, gastric mucosal perfusion was assessed, by means of laser-Doppler flowmetry and reflectance spectrophotometry, in 36 cirrhotic patients with portal-hypertensive gastropathy in basal conditions and after double-blind administration of placebo or somatostatin. Intravenous bolus injection of 250 micrograms somatostatin induced a rapid, marked decrease in gastric perfusion (-31.6% +/- 7.9%, p < 0.05), as assessed on laser-Doppler flowmetry, that lasted for only 6 min. Changes in the hemoglobin content of the gastric mucosa paralleled those of laser-Doppler signal. The oxygen content of the gastric mucosa was mildly reduced (-6.9% +/- 1.1%, p < 0.05). When the bolus injection was followed by a continuous infusion of somatostatin, the reduction in gastric perfusion, as assessed by means of laser-Doppler flowmetry, was maintained, although the magnitude of the reduction (-17% +/- 7%) was significantly lower than that observed immediately after the bolus (p < 0.05); the hemoglobin content of the gastric mucosa was also significantly reduced (-8% +/- 1%), but no changes were observed in the oxygen content. Placebo administration had no effect on any of these parameters. We conclude that the increased gastric perfusion in cirrhotic patients with portal-hypertensive gastropathy can be effectively decreased by somatostatin administration.

The present study investigated the hemodynamic effects of nicardipine, a new calcium channel blocker, and placebo in 14 patients with cirrhosis. Sixty minutes after nicardipine administration (20 mg orally; n = 8), there was a significant increase in hepatic blood flow (25 +/- 21%; p < 0.05) and azygos blood flow (33 +/- 40%; p < 0.05) but no significant change in the hepatic venous pressure gradient. As a result of the increase in hepatic blood flow and the lack of change in the hepatic venous pressure gradient, nicardipine significantly reduced hepatic sinusoidal resistance (-14 +/- 15%; p < 0.05). Enhanced liver perfusion was associated with a significant increase in the hepatic clearance of indocyanine green (from 241 +/- 81 to 265 +/- 92 ml/min, p < 0.05). A mild, well-tolerated decrease in mean arterial pressure (-10 +/- 6%, p < 0.05), without significant changes in cardiac output, systemic vascular resistance and heart rate, was also observed. Placebo administration (n = 6) did not cause significant changes in systemic or hepatic hemodynamics. The results of the present study show that nicardipine, unlike other calcium channel blockers, effectively increases hepatic blood flow and the hepatic clearance of indocyanine green in patients with cirrhosis. The acute beneficial effects of nicardipine should be confirmed in chronic studies.

Increased circulating insulin and glucagon levels are a common observation in patients with cirrhosis, as well as in portal hypertensive models. Hyperinsulinemia and hyperglucagonemia may be caused either by increased beta- and alpha-cell secretion or by defective hepatic clearance of these hormones. To elucidate whether an abnormal endocrine pancreatic function might contribute to the hyperinsulinism or to the hyperglucagonism observed in chronic portal hypertension, insulin and glucagon secretion were measured in vitro in isolated pancreatic islets from rats with partial portal vein ligated and rats with cirrhosis caused by carbon tetrachloride poisoning. Both rats with partial portal vein ligation and rats with cirrhosis caused by carbon tetrachloride poisoning exhibited hyperinsulinism and hyperglucagonism as compared with control rats. Isolated pancreatic islets from both experimental portal hypertensive models showed an impaired insulin secretion after glucose stimulation. On the contrary, glucagon secretion was significantly increased, and there was a markedly enhanced response to arginine. This increased in vitro glucagon production could not be corrected, even in the presence of high glucose concentrations in the incubation medium. Therefore our data show that although hyperglucagonism in rats with partial portal vein ligation and in rats with cirrhosis caused by carbon tetrachloride poisoning is promoted by an enhanced alpha-cell secretion, hyperinsulinism is associated with impaired beta-cell secretion.

Gastric mucosal perfusion is increased in portal-hypertensive gastropathy, and this may contribute to gastric bleeding from these lesions. Therefore drugs reducing gastric mucosal perfusion may be beneficial in the treatment of overt bleeding from portal-hypertensive gastropathy. In this study gastric mucosal perfusion was assessed in 28 cirrhotic patients with portal-hypertensive gastropathy under basal conditions and after double-blind intravenous administration of vasopressin (0.4 U/min), glypressin (2-mg injection) or placebo, with laser-Doppler flowmetry and reflectance spectrophotometry. Vasopressin and glypressin induced a significant increase in blood pressure and a decrease in heart rate. These effects were more pronounced in the vasopressin group. Both vasopressin and glypressin induced a sustained and similar reduction in gastric mucosal perfusion as assessed by laser-Doppler flowmetry (-36% +/- 8% and -34% +/- 6%, respectively; p < 0.05 with respect to basal values and with respect to the control group), whereas placebo had no effect. Both drugs significantly reduced the oxygen content of the gastric mucosa; however, the impairment in mucosal oxygenation was greater (p < 0.05) in the vasopressin group (-17% +/- 3%) than in the glypressin group (-6% +/- 0.1%). We conclude that the increased gastric perfusion in cirrhotic patients with portal-hypertensive gastropathy may be reduced by either vasopressin or glypressin. These findings support the use of these drugs in clinical trials treating bleeding portal-hypertensive gastropathy. The lower reduction in gastric mucosal oxygen content observed with glypressin could decrease the incidence of ischemic adverse events associated with the use of vasopressin.

This study investigated the short-term effects of ritanserin, a selective and specific S2-serotonergic antagonist, in an experimental model of cirrhosis and intrahepatic portal hypertension caused by long-term bile duct ligation and division and in normal control rats. The rats subjected to bile duct ligation were randomized under blind conditions into two groups to receive ritanserin (0.7 mg/kg body wt, intravenously; n = 10) or the same volume of placebo (isotonic saline solution; n = 10). We performed hemodynamic studies with radiolabeled microspheres 60 min after drug administration. Two groups of normal rats (n = 6) were studied after they received ritanserin or placebo. Ritanserin administration to rats subjected to bile duct ligation significantly reduced portal pressure (from 16.2 +/- 1.3 mm Hg to 12.3 +/- 0.7 mm Hg; mean decrease, 22% +/- 5%; p < 0.05). This reduction was associated with lower portal venous resistance (4.3 +/- 0.5 mm Hg.min.100gm/ml in the placebo group vs. 3.1 +/- 0.3 mm Hg.min.100 gm/ml in rats given ritanserin; mean decrease, 28%; p = 0.069), but we saw no changes in portal vein inflow (3.9 +/- 0.5 ml/min.100 gm vs. 4.4 +/- 0.4 ml/min.100 gm), mean arterial pressure (110 +/- 9 mm Hg vs. 102 +/- 9 mm Hg) and cardiac index (32.9 +/- 2.7 ml/min.100 gm vs. 40.5 +/- 6.7 ml/min.100 gm). Hepatic arterial and kidney blood flows were not modified by ritanserin. Ritanserin had no systemic or splanchnic effects in normal rats. Our results demonstrate that ritanserin infusion decreases portal pressure without any systemic hemodynamic change in rats with secondary biliary cirrhosis and portal hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

This study investigated the effects of the short-term administration of propranolol on gastric blood perfusion in cirrhotic patients with portal hypertensive gastropathy. Portal hypertensive gastropathy is a common cause of nonvariceal bleeding in cirrhosis, which is associated with increased gastric mucosal perfusion and is favorably influenced by propranolol therapy. Gastric mucosal perfusion was evaluated with laser-Doppler flowmetry and reflectance spectrophotometry. Measurements were performed under basal conditions and after the double-blind administration of propranolol (0.15 mg/kg intravenously) or placebo. Propranolol administration significantly reduced (p < 0.001) the laser-Doppler signal (2.93 +/- 0.23 vs. 2.25 +/- 0.22 V) and the hemoglobin content of the gastric mucosa (99.2 +/- 3.8 vs. 89.3 +/- 3.1 arbitrary units), whereas the oxygen content remained unchanged (37.4 +/- 1.2 vs. 36.9 +/- 1.0 arbitrary units). Placebo administration had no effect in any of these parameters. Changes in gastric perfusion after propranolol administration were associated with a significant decrease in hepatic venous pressure gradient and azygos blood flow. We conclude that short-term propranolol administration, in addition to lowering portal pressure, reduces the increased gastric blood perfusion in cirrhotic patients with portal hypertensive gastropathy, an effect that may contribute to prevention of bleeding from these lesions.

To alleviate the risk of variceal bleeding, the portal pressure gradient--usually evaluated as the hepatic venous pressure gradient (HVPG)--must be reduced to < or = 12 mmHg. Although beta-blocking agents are accepted therapy for preventing first or subsequent bleeding episodes, propranolol therapy decreases final HVPG to < or = 12 mmHg in only 12% of patients, while only 24% of patients have a > or = 20% reduction in HVPG and nearly 40% show no reduction in HVPG. This has stimulated research on alternative or additional treatments. Nitrates such as isosorbide dinitrate reduce portal pressure by decreasing resistance to portal and collateral blood flow and by promoting reflex splanchnic vasoconstriction. However, while nitrates are effective in the acute situation, tolerance leading to refractoriness develops over the long term unless they are combined with diuretics or other agents in the treatment of portal hypertension. Propranolol and isosorbide-5-mononitrate combined cause a substantially greater reduction in HVPG than monotherapy with either drug in both acute and long-term use. Presumably concomitant isosorbide-5-mononitrate administration opposes the increase in portal resistance induced by propranolol. Spironolactone, which has been shown to lower HVPG in patients with cirrhosis, produces a reduction in plasma volume that attenuates the increased cardiac output associated with cirrhosis and triggers vasoactive mechanisms that decrease splanchnic blood flow. Potentially, spironolactone may maintain and enhance the decrease in portal pressure achieved by nitrates or propranolol. Triple therapy with a beta-blocker, a nitrate and spironolactone may be feasible.(ABSTRACT TRUNCATED AT 250 WORDS)

To characterize gastric mucosal perfusion in cirrhotic patients with portal hypertensive gastropathy, 34 cirrhotics with this lesion and 24 noncirrhotics were studied by reflectance spectrophotometry and laser-Doppler flowmetry during endoscopy. A significant correlation was observed between the hemoglobin content of the gastric mucosa, measured by reflectance spectrophotometry, and the serum hemoglobin concentration both in cirrhotics (r = 0.72) and in noncirrhotics (r = 0.87). IHb ratio (hemoglobin content of gastric mucosa divided by blood hemoglobin concentration) was higher in cirrhotics with portal hypertensive gastropathy than in noncirrhotics (P < 0.001), whereas the oxygen content of the gastric mucosa was similar in both groups. This pattern indicates that cirrhotics with portal hypertensive gastropathy have increased gastric perfusion without congestion. Gastric blood flow estimated by laser-Doppler was significantly higher in cirrhotics with portal hypertensive gastropathy than in noncirrhotics (P < 0.001). In cirrhotic patients, gastric areas with cherry red spots showed a significantly higher IHb ratio than areas with a mosaic or scarlatina pattern (P < 0.05). The magnitude of changes in gastric perfusion and the endoscopic severity of portal hypertensive gastropathy had no relationship with the degree of portal hypertension or the azygos blood flow.

Twenty five patients with acute liver failure were measured for hepatic venous pressure gradient as an index of portal pressure during the course of a transjugular liver biopsy. Hepatic venous pressure gradient ranged from 4 to 24.5 mm Hg with a mean of 12.8 (5.3) mm Hg (normal values less than 5 mm Hg). All patients but one had increased portal pressure gradient. Portal hypertension correlated with the degree of architectural distortion of the liver, as suggested by a direct correlation between hepatic venous pressure gradient and the area of reticulin collapse, evaluated by means of a morphometric analysis on Sirius red stained liver slides (r = 0.43, p less than 0.05). Hepatic venous pressure gradient was significantly higher in patients with ascites (15.1 (5) mm Hg, n = 15) or renal failure (14.4 (5.3) mm Hg, n = 16) than in those without (9.3 (3.4) mm Hg and 10.1 (4) mm Hg, respectively; p less than 0.05). Portal hypertension was associated with systemic vasodilation and a hyperkinetic circulatory state, with decreased arterial pressure, and peripheral resistance and increased cardiac output.

Whether the decrease of portal venous inflow and portal pressure induced by somatostatin is related to the effects of somatostatin in inhibiting the secretion of glucagon and other vasodilatory peptides that are increased in portal hypertension was investigated in the current study. Splanchnic vascular resistance and splanchnic blood flow were determined using radioactive microspheres in rats with portal hypertension caused by partial portal vein ligation. Somatostatin infusion significantly decreased portal pressure (from 13.1 +/- 1.9 to 12.1 +/- 2.2 mm Hg; P less than 0.05). This was associated with a significant decrease in portal venous inflow caused by splanchnic vasoconstriction, as evidenced by increased splanchnic vascular resistance, and with a marked suppression of glucagon secretion. The simultaneous infusion of somatostatin and glucagon (2.8 ng/min, a dose that prevented any decrease in circulating glucagon levels) abolished all the hemodynamic effects of somatostatin. This effect seems to be specific because no hemodynamic changes were noted in portal hypertensive rats receiving only the glucagon infusion.

Serotonergic mechanisms have recently been implicated in the pathogenesis of portal hypertension; this suggests that blockade of serotonin S2 receptors may be a new approach for the pharmacological therapy of portal hypertension. This study was aimed at investigating the effects of ritanserin, a selective S2-serotonergic antagonist, in portal-hypertensive rats whose condition was due to partial portal vein ligation. The animals were randomized under double-blind conditions into two groups: the first received ritanserin (0.7 mg/kg body wt, intravenously), and the second received the same volume of placebo (isotonic saline solution). The hemodynamic studies were performed using radiolabeled microspheres 60 min after drug administration. Ritanserin administration significantly reduced portal pressure (from 11.8 +/- 0.8 mm Hg to 9.4 +/- 0.6 mm Hg; p less than 0.05). This was associated with lower portocollateral resistance (1.8 +/- 0.2 mm Hg/ml/min 100 gm in the ritanserin group vs. 2.3 +/- 0.2 mm Hg/ml/min 100 gm in rats receiving placebo; not significant), but we saw no changes in portal-vein inflow (5.5 +/- 0.7 ml/min 100 gm vs. 5.4 +/- 0.5 ml/min 100 gm), mean arterial pressure (95.9 +/- 3.5 mm Hg vs. 94.0 +/- 4.0 mm Hg) and cardiac index (31.9 +/- 3.5 ml/min 100 gm vs. 28.5 +/- 2.6 ml/min 100 gm). Hepatic arterial and kidney blood flows were not modified by ritanserin. In summary, our results demonstrate that ritanserin infusion decreases portal pressure without causing systemic hemodynamic changes. This effect is probably due to a decrease in portocollateral resistance in portal-hypertensive rats. These results provide further for a role of serotonin in the pathogenesis of portal hypertension.

The present study investigated the effects of molsidomine, a predominant venous dilator which, contrary to organic nitrates, does not produce pharmacological tolerance on splanchnic and systemic hemodynamics in patients with cirrhosis. Twenty-seven cirrhotic portal hypertensive patients were studied prior to and up to 2 h after the oral administration of 2 mg of molsidomine (n = 11), 4 mg of molsidomine (n = 8) or placebo (n = 8). Molsidomine caused a significant reduction in the hepatic venous pressure gradient. The mean decrease at 60 min was -6.8 +/- 9% after 2 mg (p less than 0.05) and -15.4 +/- 12% after 4 mg (p less than 0.01). The decrease in the hepatic venous pressure gradient was maintained at 120 min: -11% after 2 mg (p less than 0.05) and -19% with 4 mg (p less than 0.01). This was associated with mild changes in azygos blood flow and with a significant decrease in hepatic blood flow (-17%, p less than 0.05). There was a moderate reduction in mean arterial pressure (-12.6% after 2 mg and -13.2% after 4 mg, p less than 0.01), which was due to a reduction in cardiac output, without any significant fall in systemic vascular resistance. Placebo administration did not change systemic or hepatic hemodynamics. This study shows that molsidomine causes a significant and sustained reduction in portal pressure in patients with cirrhosis, suggesting the potential role of this agent in the treatment of portal hypertension.

Objective: To investigate whether isosorbide-5-mononitrate (Is-5-Mn) given with propranolol reduces hepatic portal pressure more than does propranolol alone in patients with cirrhosis., Design: A randomized controlled trial., Patients: Fifty patients with cirrhosis and esophageal varices entered and 42 completed the study., Intervention: Twenty-one patients received oral propranolol at increasing doses until their resting heart rate was reduced by 25%, and 21 patients received oral propranolol (on the same schedule) plus oral Is-5-Mn, 40 mg twice a day., Measurements: Hepatic vein pressure gradient, liver function, and splanchnic and systemic hemodynamics before and after 3 months of continuous therapy., Main Results: At 3 months, the hepatic venous pressure gradient decreased more (P less than 0.01) in patients given propranolol plus Is-5-Mn (19%, from 18.4 +/- 3.9 to 14.9 +/- 3.8 mm Hg; 95% CI, -2.4 to -4.5 mm Hg) than in those given propranolol alone (10%, from 18.2 +/- 3.5 to 16.3 +/- 3.1 mm Hg; CI, -1.1 to -2.7 mm Hg). The hepatic venous pressure gradient decreased by more than 20% of the baseline value in 10% of patients receiving propranolol, but in 50% of patients receiving combined therapy (P less than 0.02). There were statistically significant decreases in hepatic blood flow and the intrinsic clearance of indocyanine green after propranolol therapy, but not after combined therapy. The treatments caused similar reductions in azygos blood flow and cardiac output., Conclusions: The long-term combined administration of propranolol plus Is-5-Mn reduces portal pressure more than propranolol alone without adverse effects on hepatic perfusion and liver function. Whether this greater hemodynamic effect translates into better clinical efficacy should be determined in randomized controlled trials.

This study was aimed at investigating the effects of propranolol on esophageal variceal pressure in patients with portal hypertension. Variceal pressure was measured at endoscopy using a miniature pressure-sensitive gauge in 20 patients with portal hypertension. Measurements were obtained under baseline conditions and 20 min after double-blind administration of propranolol (0.15 mg/kg; n = 10) or an identical amount of placebo (normal saline, 0.3 ml/kg; n = 10). Under baseline conditions, variceal pressure was similar in propranolol and placebo groups (14.1 +/- 5 mm Hg vs. 14.9 +/- 6.6 mm Hg, respectively; not significant). Placebo had no significant effect on variceal pressure (baseline = 14.9 +/- 6.6 mm Hg; placebo = 15.5 +/- 6.6 mm Hg; not significant), and values after placebo administration were closely correlated with baseline values (r = 0.98; y = 1.1 + 0.97 x; p less than 0.0001). In contrast, propranolol caused a significant decrease in the pressure of esophageal varices (from 14.1 +/- 5 mm Hg to 11.3 +/- 4.4 mm Hg; p less than 0.0002). No significant changes in the size of esophageal varices were observed after propranolol or placebo administration. This study shows (a) the endoscopic pressure-gauge technique has a low variability and may be used to assess acute drug-induced changes in variceal pressure; and (b) propranolol causes significant decreases in variceal pressure in patients with portal hypertension and esophageal varices.

Since it is well known that pharmacological tolerance may rapidly occur on continuous administration of organic nitrates, in this study we attempted to investigate whether isosorbide 5-mononitrate (Is-5-Mn), a long-acting vasodilator that decreases portal pressure in acute haemodynamic studies, causes a significant reduction in portal pressure following long-term oral administration. Eleven patients with cirrhosis and portal hypertension were studied prior to and following 3 months of continuous administration of Is-5-Mn, 40 mg b.i.d. The hepatic venous pressure gradient decreased significantly following long-term Is-5-Mn treatment (from 18.6 +/- 3.4 to 17.2 +/- 3.1 mmHg; p less than 0.01). This was associated with a moderate increase in hepatic blood flow. Azygos blood flow and portal blood flow did not change. There were significant decreases in mean arterial pressure (from 89.4 +/- 13.7 to 82.6 +/- 10.8 mmHg; p less than 0.05) and heart rate (from 77 +/- 10 to 73 +/- 10 b.p.m.; p less than 0.05). In contrast, there were no changes in portal pressure or hepatic and systemic haemodynamics in a control group of 17 patients receiving placebo. Repeated nitroglycerin cross-tolerance studies in five patients receiving Is-5-Mn indicated the development of a partial pharmacological tolerance (as shown by blunted haemodynamic response to nitroglycerin after long-term Is-5-Mn administration). This study shows that Is-5-Mn continues to cause a significant decrease in portal pressure during long-term therapy, with only partial pharmacological tolerance to this compound.

It has been suggested that glucagon contributes to the pathogenesis of portal hypertension by increasing portal blood flow. This study examined this issue by assessing the hemodynamic effects of a pharmacological dose of glucagon (1 mg, intravenously) in patients with cirrhosis and portal hypertension (n = 10) and in subjects without significant liver disease (controls = n = 5). Patients with cirrhosis had much higher glucagon levels than control subjects (875 +/- 167 vs. 186 +/- 25 pg/ml, p less than 0.01) and showed blunted hemodynamic responses after glucagon administration. This occurred despite greater circulating glucagon levels, probably because of a significant prolongation of the plasma half-life of exogenously administered glucagon (4.9 +/- 0.4 vs. 2.7 +/- 0.1 min, p less than 0.1). Control subjects had marked increases in heart rate (+ 19% +/- 4%, p less than 0.01), cardiac index (+ 16% +/- 4%, p = 0.01) and arterial pressure (+ 10% +/- 3%, p less than 0.05), but corresponding changes in patients with cirrhosis (+ 7% +/- 1%, + 6% +/- 1%, and + 6% +/- 2%, respectively) were significantly less pronounced (p = 0.05), and there was a negative correlation between basal glucagon levels and the response of heart rate to glucagon injection (r = -0.804, p less than 0.001). Resistance to the systemic effects of glucagon in cirrhosis may thus be caused by a down-regulation of vascular glucagon receptors. In addition, glucagon administration caused a significant increase in portal pressure (from 18.1 +/- 1.1 to 19.0 +/- 1.2 mm Hg, p less than 0.01), as well as in azygos blood flow (from 0.54 +/- 0.03 to 0.64 +/- 0.04 L/min, + 19% +/- 4%, p less than 0.02), reflecting increased portocollateral blood flow. These findings are consistent with the hypothesis that glucagon is one of the factors contributing to the splanchnic vasodilatation and increased portal pressure of cirrhosis.

This study examined whether hyperglucagonism may promote an altered sensitivity to norepinephrine (NE) and contribute to systemic vasodilation in rats with portal hypertension due to portal vein stenosis. Three groups of male Sprague-Dawley rats were studied, portal hypertensive, normal controls, and hyperglucagonemic controls. Systemic vascular reactivity was studied by constructing dose-response curves of systemic vascular resistance (SVR) during infusions of increasing doses of NE and calculating NE ED50, the dose of NE that caused 50% of the maximal increase in SVR. Measurement of SVR was based on simultaneous measurements of arterial pressure and cardiac output (CO). Repeated measurements of CO were performed by indicator dilution curves of indocyanine green by means of a fiber-optic catheter placed in the carotid artery. Portal hypertensive rats had a decreased systemic sensitivity to NE, shown by a significant increase in NE ED50 compared with normal controls (60 +/- 8 micrograms vs. 25 +/- 3 micrograms; P less than 0.001). Glucagon levels were markedly increased in the portal hypertensive group (332 +/- 51 pg/ml vs. 176 +/- 22 pg/ml in controls; P less than 0.005). Glucagon infusion in normal rats achieved levels similar to those observed in portal hypertension (305 +/- 48 pg/ml; NS). Systemic vascular sensitivity to NE was also impaired in these hyperglucagonemic normal animals, as shown by an abnormal NE ED50 (69 +/- 16 micrograms; P less than 0.001 vs. controls) that was almost identical to that observed in portal hypertension. These results are consistent with the hypothesis that a reduced sensitivity to NE can contribute to systemic vasodilation in portal hypertension and suggest that hyperglucagonism can play a key role in its pathogenesis.

This study investigated whether oral doses of isosorbide-5-mononitrate, a preferential venous dilator that decreases portal pressure, could enhance the effects of propranolol on portal hypertension. Taking part in the study were 28 patients with cirrhosis and portal hypertension. Twenty patients (group 1) had hemodynamic measurements in baseline conditions after beta-blockade by intravenous administration of propranolol and after receiving oral doses of isosorbide-5-mononitrate. The remaining eight patients (group 2) were given oral isosorbide-5-mononitrate while receiving chronic propranolol therapy. In group 1, propranolol significantly reduced portal pressure (estimated as the gradient between wedged and free hepatic venous pressures) from 21.5 +/- 3.9 to 18.6 +/- 4.2 mm Hg (-13.7%, p less than 0.001), azygos blood flow (-38%, p less than 0.001), hepatic blood flow (-12.8%, p less than 0.05), cardiac output (-24.5%, p less than 0.001) and heart rate (-18.4%, p less than 0.001) without significant changes in mean arterial pressure. Addition of oral isosorbide-5-mononitrate caused a further and marked fall in portal pressure (to 15.7 +/- 3.1 mm Hg, p less than 0.001), without additional changes in azygos blood flow but with significant additional reductions in hepatic blood flow (-15.5%, p less than 0.05), cardiac output (-11.5%, p less than 0.001) and mean arterial pressure (-22%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

The results of a study to characterize the effects of the oral administration of isosorbide-5-mononitrate (Is-5-Mn), the active metabolite of isosorbide dinitrate, on portal hypertension in 23 patients with cirrhosis are reported. Patients received 20 mg of Is-5-Mn (n = 10), 40 mg (n = 9), or a placebo (n = 4). No significant changes were observed after the administration of the placebo. However, both doses of Is-5-Mn significantly reduced portal pressure, as evaluated by measurements of the hepatic venous pressure gradient. The fall in portal pressure averaged 10% after the 20-mg dose and 18% after 40 mg and was maintained for the 2 h of observation. Reduction of portal pressure was due to a decrease in the wedged hepatic vein pressure, with no changes in the free hepatic venous pressure. After the 20-mg dose, the decrease in portal pressure was associated with an increase in hepatic blood flow (16%), suggesting a fall in hepatic vascular resistance. However, after the 40-mg dose, a reflex splanchnic vasoconstriction elicited by the fall in arterial pressure (-19%) appeared to contribute to the greater reduction in portal pressure, as suggested by a significant decrease in azygos blood flow (-15%). These beneficial effects on portal pressure were not associated with adverse effects on liver function, as evaluated by measurements of the hepatic clearance of indocyanine green and the hepatic intrinsic clearance. Neither dose of Is-5-Mn caused significant changes in these quantitative parameters of liver function. These findings suggest that Is-5-Mn could be a potentially useful and safe agent in the treatment of portal hypertension.

The effects of pharmacological manipulation of the lower esophageal sphincter pressure on the esophageal circulation in patients with cirrhosis and portal hypertension were investigated in 33 patients by measuring the azygos venous blood flow, which is an index of blood flow through esophageal varices and periesophageal collaterals draining into the azygos venous system. Measurements were performed in baseline conditions and after the blind administration of metoclopramide (20 mg i.v.) (12 patients), domperidone (10 mg i.v.) (12 patients) and placebo (9 patients). Both metoclopramide and domperidone caused a significant reduction of azygos blood flow, that decreased by 11.5% (p less than 0.01) and 15.6% (p less than 0.02) respectively, while no change was observed in patients receiving placebo (+1.4%, not statistically significant). Reduction of azygos blood flow represents a selective effect of metoclopramide and domperidone on the esophageal circulation, since portal pressure, hepatic blood flow, cardiac output, heart rate and arterial blood pressure were unchanged by the administration of metoclopramide, domperidone or placebo. These results indicate that the administration of drugs that increase the lower esophageal sphincter pressure may reduce the inflow of blood into the esophageal varices in cirrhotic patients with portal hypertension.

Portal hypertension has been studied in the rat to see if it is associated to altered blood volume composition, as it has been shown in other species. Plasma volume was measured by isotope dilution using 99mTc labelled albumin in three groups of male Sprague-Dawley rats: normal rats (controls), partially ligated portal vein rats and rats with Cl4C induced cirrhosis. Plasma volume was significantly higher in rats with portal hypertension due to partially ligated portal vein and cirrhosis than in control animals. Similarly, the calculated blood volume was also significantly higher in the portal hypertensive animals than in control group. Portal hypertension in the rat, therefore, has been demonstrated to be associated to a marked hypervolemia and this finding should be taken into consideration in haemodynamic and pharmacokinetic studies in portal hypertensive rat models.

In the past recent years there have been several major innovations in the diagnosis and evaluation of portal hypertension. These include the application of new endoscopic, ultrasonographic and haemodynamic techniques that allow a better evaluation of the portal hypertensive patient, specially when prophylactic medical therapy is considered. Ultrasonography is very useful to assess the patency of the portal vein. The association of a pulsed Doppler flowmeter increases its accuracy and allows the non-invasive estimation of the direction and magnitude of portal blood flow. Endoscopic measurements of variceal pressure may help to understand the mechanism of variceal bleeding, and perhaps might permit to assess the risk of haemorrhage in the individual patient. In addition to the measurement of portal pressure, measurement of blood flow through the azygos vein has been the major innovation in the haemodynamic evaluation of portal hypertension. Azygos blood flow represents an index of blood flow through gastroesophageal collaterals and varices draining in the azygos vein. This technique has been very useful in the development of new forms of pharmacological therapy for portal hypertension.

Measurements of variceal pressure with a noninvasive endoscopic pressure gauge and by direct variceal puncture were performed in 20 cirrhotic patients with portal hypertension in the course of the first session of therapeutic sclerotherapy following an episode of variceal bleeding. Endoscopic gauge measurements of the pressure of esophageal varices gave similar values (15.5 +/- 2.7 mm Hg) than measurements by variceal puncture (15.4 +/- 2.4 mm Hg; not statistically significant), and there was a highly significant linear correlation between both measurements (r = 0.9, p less than 0.001). Azygos blood flow, that was markedly increased in these patients (852 +/- 399 ml per min), was directly related to variceal pressure (r = 0.73, p less than 0.01). Variceal pressure was significantly lower than portal pressure (18.8 +/- 5.0 mm Hg) (p less than 0.05), indicating that measurements of variceal pressure cannot substitute measurements of portal pressure. The study demonstrates that the noninvasive endoscopic gauge technique allows an accurate estimation of variceal pressure in patients with portal hypertension. This technique may provide additional useful information in the evaluation of portal hypertension as well as on the mechanism of variceal bleeding.

The effects of verapamil on hepatic and systemic hemodynamics and on liver function were investigated in 10 patients with portal hypertension due to advanced micronodular cirrhosis to verify whether, as it has been suggested, this calcium channel blocker may improve liver function and reduce portal pressure in these patients. The oral administration of 100 mg of verapamil caused systemic vasodilation, evidenced by a significant reduction in mean arterial pressure (-8.1 +/- 7.6%, p less than 0.025) and systemic vascular resistance (-12.5 +/- 9.5%, p less than 0.001), and increased heart rate (+13.9 +/- 10.4%, p less than 0.01). However, no beneficial effect was noted on portal pressure evaluated by hepatic vein catheterization (baseline 19.8 +/- 4.0, verapamil 20.2 +/- 3.6 mmHg, NS), hepatic blood flow (1.45 +/- 0.64 vs. 1.47 +/- 0.62 liters per min, NS) and hepatic vascular resistance (1.314 +/- 611 vs. 1,266 +/- 513 dyn per sec per cm-5, NS). Similarly, no change was observed in portal blood flow, measured in six patients by pulsed Doppler flowmeter (0.94 +/- 0.30 vs. 0.89 +/- 0.35 liter per min, NS). In addition, verapamil did not increase the hepatic intrinsic clearance of these patients (0.20 +/- 0.07 vs. 0.19 +/- 0.06 liter per min, NS). This study suggests that verapamil is of no beneficial effect in patients with advanced cirrhosis of the liver.