Hepatopetal Portal Blood Flow Research Articles

Rex Shunt for Extra-Hepatic Portal Venous Obstruction in Children

Rex shunt, which was first put in use in 1992, has been considered as an ideal surgical method for the treatment of extra-hepatic portal venous obstruction (EHPVO) due to its reconstruction of the hepatopetal portal blood flow. However, despite its long tradition, there are only a few reports about the application and advances in Rex shunt for the treatment of EHPVO in children. In this paper, we summarized the literature related to Rex shunt and discussed the new advances of Rex shunt in the following aspects: surgical method of Rex shunt, the indications of Rex shunt, the strengths of Rex shunt, the effectiveness of Rex shunt, factors affecting the efficacy of Rex shunt, methods that improve the prognosis of Rex shunt, and treatment strategy for recurrence after Rex shunt.

Proof of principle: Estimation of liver function using color coded Doppler sonography of the portal vein

The diagnostic value of Doppler ultrasonography of the portal vein for the evaluation of liver function is still contradictory. Aim of this study was to test the relationship between clinical liver function tests based on MRI and breath testing and blood flow in the portal vein. The portal vein velocity was measured by color coded Doppler ultrasonography (CCDS) and tested against the relative enhancement (RE), a MRI-based index of liver function. The signal intensity in the liver parenchyma was assessed before (pre) and after (post) administration of contrast agent, the RE was calculated afterwards. Further, the liver function was also assessed using a 13C-Methacetin-based breath test. The blood flow in the portal vein was tested for possible correlation applying Pearson's correlation coefficient. Using CCDS, all patients show a hepatopetal portal blood flow. The portal vein velocity is decreasing with progression of liver damage and there was a significant correlation of portal velocity with SI post (r = 0.411, p = 0.024). However, the portal velocity did not correlate significantly with the 13C-MBT readout (r = 0.233; p = 0.216), SI pre (r = 0.271, p = 0.147) or the relative enhancement (r = 0.303; p = 0.103). The results of this proof-of-principle study indicate that CCDS-based assessment of portal velocity is of only limited value for the evaluation of liver function.

Liver AL amyloidosis as a possible cause of high liver stiffness values

The liver is a common site of amyloid deposition in primary systemic amyloidosis. We report the case of a 52-year-old white woman complaining of hepatomegaly, high levels of alkaline phosphatase and serum gamma-glutamyl transferase. Other laboratory tests showed proteinuria with light-chain type lambda. Color Doppler ultrasonography showed an enlarged bright liver with hepatopetal portal blood flow. Fine-needle aspiration biopsy of abdominal fat, with Congo red stain, was positive for amyloid. No liver biopsy was performed, but transient elastography showed high liver stiffness values (75 kPa), suggestive of amyloid infiltration, as other causes of elevation had been ruled out by clinical, laboratory and radiological findings. Bone marrow morphology and immunoistochemistry confirmed low-grade plasmacytoma with amyloidosis.

Improved body mass index after mesenterico-portal bypass

Extrahepatic portal hypertension in children secondary to portal vein obstruction is frequently associated with impaired somatic growth. The aim of this study was to assess growth and nutritional status, as reflected by the body mass index (BMI), before and after mesenterico-portal bypass (Rex shunt). Eleven children with a portal vein cavernoma underwent mesenterico-portal bypass using autologous jugular vein. All shunts have remained patent during follow-up periods of 7 months to 5 years. All except one child, who had a normal BMI prior to surgery, demonstrated an increase in their BMI standard deviation scores after surgery. Mean BMI standard deviation scores increased from -0.44 +/- 1.28 (95% CI -1.30 to 0.42) to 0.46 +/- 1.08 (95% CI -0.27 to 1.19), a highly statistically significant increase (P=0.003). Restoration of hepatopetal portal blood flow by mesenterico-portal bypass surgery improves nutrition and growth in children with extrahepatic portal hypertension.

Mesenterico left portal bypass for variceal bleeding owing to extrahepatic portal hypertension caused by portal vein thrombosis

Background/Purpose Portosystemic shunt operations are indicated in patients with extrahepatic portal hypertension owing to portal vein thrombosis (EPH-PVT) suffering from recurrent variceal bleeding despite endoscopic sclerotherapy. Mesenterico left portal bypass procedure (MLPB) is an alternative procedure to the portosystemic shunt operations in patients with EPH-PVT. MLPB operation reestablishes hepatopetal portal blood flow. We herein present our experience with MLPB in children with EPH-PVT. Methods Six patients were treated for EPH-PVT with recurrent bleeding despite endoscopic sclerotherapy (2 boys and 4 girls) in our unit. All patients were evaluated preoperatively with complete blood count, portal duplex system Doppler ultrasonography, magnetic resonance angiography, and upper gastrointestinal (GI) endoscopy. MLPB operation was performed as described by de Ville de Goyet. During the postoperative period, patients were evaluated with complete blood count, portal duplex system Doppler ultrasonography, upper GI endoscopy, and magnetic resonance angiography. Results Six patients were assessed to be candidates for MLPB procedure and were operated to perform the MLPB procedure. Left portal veins were found to be patent during the operation in 4 patients, and the MLPB procedure was performed. Internal jugular vein was used in 3 patients and enlarged inferior mesenteric vein in 1 patient. Left portal veins of the remaining 2 patients were found to be obliterated; therefore, mesocaval shunt was performed. The postoperative course of the patients was uneventful except for 1 patient. During the following period, the leukocyte and the platelet counts were significantly increased in 3 of the 4 patients after the MLPB procedure. Upper GI bleeding occurred in the early postoperative period in 1 patient with MLPB procedure because of prepyloric ulcer that was successfully treated by endoscopic sclerotherapy. Internal jugular vein graft thrombosis was detected on the 10th postoperative day. This patient underwent a second laparotomy, the distal half of the graft was found to be sclerosed and narrowed that the graft was revised with a synthetic allograft. Conclusions Based on a review of the literature, the MLPB functions well in patients with portal hypertension caused by portal vein thrombosis and appears to have a physiologic advance over shunts that decompress but do not return blood directly to the liver. Because intra-abdominal veins appear to function well as a conduit in this operation, it may be favored by eliminating additional incision and increased risk in such patients.

Ultrasonography of Portosystemic Shunts in Dogs and Cats

Ultrasonography is a rapid, accurate, noninvasive diagnostic test for primary (congenital) and secondary (acquired) portosystemic shunting in dogs and cats. Two-dimensional, gray-scale ultrasonography alone enables diagnosis of most congenital portosystemic shunts and determination of intra- versus extrahepatic location. Use of duplex- and color-flow Doppler ultrasonography aids detection of congenital and acquired extrahepatic portosystemic shunts. The underlying cause of acquired portosystemic shunting is portal hypertension; this may be documented by finding either hepatofugal or reduced velocity hepatopetal portal blood flow by duplex-Doppler. Also, ultrasonography may enable detection of lesions involved in the pathogenesis of portal hypertension, for example, hepatic arterioportal fistula, hepatic parenchymal lesions, and portal vein thrombosis.

Effects of L-arginine on the systemic, mesenteric, and hepatic circulation in patients with cirrhosis.

Nitric oxide (NO) is known to play an important role in modulating both the hepatic and mesenteric circulation under physiological and pathological conditions. We investigated how L-arginine, a precursor of NO, modifies the hepatic and mesenteric circulation in patients with cirrhosis. The study design was a single-blind controlled study. We measured the systemic and portal hemodynamics before and following intravenous L-arginine and saline infusion using pulsed Doppler ultrasonography in 20 patients with cirrhosis, and then the effects were compared with those found in 20 healthy subjects. In these patients, the effects of L-arginine on hepatic circulation were investigated using hepatic catheterization. L-Arginine infusion induced systemic vasodilation in both the healthy controls and the cirrhotic patients in a similar hemodynamic manner. In these patients, the L-arginine-induced increase in the portal flow was significantly higher than that of cardiac output (CO); however, the relation was the inverse in healthy subjects. Moreover, the L-arginine-induced increase in the portal flow was greater in the cirrhotic patients than that seen in healthy subjects. As a result, L-arginine infusion was thus found to selectively augment the hepatopetal portal blood flow in the cirrhotic liver. In patients, L-arginine infusion induced marked hepatic vasodilation as demonstrated by the reduced hepatic sinusoidal resistance (HSR) and increased estimated hepatic blood flow (EHBF) associated with the ameliorated intrinsic clearance of indocyanine green. Despite the fall in HSR, the hepatic venous pressure gradient (HVPG) increased following L-arginine infusion. The mesenteric and hepatic vascular areas of cirrhosis exhibited an increased susceptibility to the dilator action of L-arginine. These findings suggest that the enhanced NO production in the splanchnic vascular area has an important role in the hepatic circulation in patients with cirrhosis.

Total hepatofugal portal blood flow in cirrhosis demonstrated by transhepatic portography.

We investigated 108 patients with cirrhosis of the liver and portal hypertension by percutaneous transhepatic portography to demonstrate the occurrence and frequency of total hepatofugal portal blood flow. Sixteen patients (14.8%) had a total hepatofugal portal blood flow. The aetiology of portal hypertension and the portal pressure did not differ from that in the group of patients with hepatopetal portal blood flow. A significantly higher percentage of patients in the group with hepatofugal flow had gastro-oesophageal varices (P less than 0.025). All patients with varices had bled. Half of the patients in the group with hepatofugal blood flow had a false splenoportographic diagnosis of portal vein thrombosis. In conclusion, total hepatofugal postal blood flow exists more often than hitherto assumed. Hepatofugal blood flow does not relieve portal hypertension nor prevent development of gastrooesophageal varices or bleeding.

Angiographic, hemodynamic, and histologic evaluation of portal hypertension and periportal fibrosis induced in the dog by retrograde biliary injections of sesame oil.

Periportal fibrosis and portal hypertension were induced by periodic retrograde biliary injections of sesame oil for two to three months in 12 cholecystectomized dogs equipped with Thomas cannulas. Stable portal hypertension between 18 and 24 cm of water occurred in four of 12 dogs (baseline: 10.4 +/- 0.5 cm of water); the remaining eight dogs required continuous biliary oil injections to maintain the portal pressure in that range. Portosystemic venous collaterals were first seen three weeks after the initial biliary oil injection and were extensively developed after two months. Hepatopetal portal blood flow decreased 61 +/- 5% during the first six months, with the greatest decrease of 32 +/- 4% occurring in the first month. Hepatic arterial flow did not change in the first month and then began to rise slowly to peak at nine months at 170 +/- 32% of its baseline value. The greatest increase in hepatic arterial flow was found between the sixth and ninth month when the portal flow no longer changed significantly. Hepatic fibrosis originating from the portal triads and around extravasated oil droplets appeared to progress slowly during the entire observation period. Animals with advanced hepatic fibrosis remained in satisfactory general health with liver enzymes usually remaining in the high normal to low pathologic range, allowing extensive follow-up examinations at regular intervals.

Hepatic blood flow after canine portasystemic shunting.

Effects of portasystemic shunting on total hepatic blood flow (THBF) were evaluated in mongrel dogs with 35 and 50micro radioactive microspheres. THBF was measured prior to shunting and 1 hour and 3 weeks after surgery. Using systemic and pulmonary artery catheters, pertinent hemodynamic variables were also measured. In sham-operated dogs (n = 5), there were no significant changes in the hemodynamic parameters or the components of THBF during the experiment. After end-to-side shunting (n = 7), animals experienced a significant, permanent fall in hepatopetal portal blood flow (HABF). In contrast, dogs with side-to-side shunts (n = 7) exhibited a transient, significant increase in HABF 1 hour after surgery. Although the shunt eliminated HPBF, the rise in HABF prevented a significant, immediate fall in THBF. Three weeks after surgery, however, HABF had returned to the baseline range, and THBF was significantly lower than the preshunt value. Dogs with H-graft mesocaval shunts (n = 5) also exhibited a transient, significant rise in HABF 1 hour after surgery. Since HPBF did not fall substantially, THBF at this time was significantly higher than the baseline value. Three weeks after surgery, HABF had fallen to the baseline range, but THBF was not significantly different from the preshunt level. In animals with distal splenorenal shunts (n = 11), there was no significant change in HABF after shunting. Both HPBF and THBF were transiently, significantly reduced immediately after surgery, but three weeks later neither parameter was significantly lower than the preshunt values. There were no significant, persistent changes in the systemic perfusion pressures or flows in the shunted groups. These experiments demonstrate that the reported increase in HABF following portasystemic shunting is dependent on the type of shunt and, if it occurs, is a transient phenomenon. Hence, immediate postoperative changes in hemodynamic variables or hepatic blood flows do not necessarily reflect long-term patterns. In the normal dog, total portasystemic shunting produces a permanent, significant decrease in THBF, whereas selective shunting maintains THBF in the near-normal range.

A Randomized, Controlled Trial of the Distal Splenorenal Shunt

In 1971 a prospective, randomized trial was initiated to determine efficacy of the distal splenorenal shunt in the management of cirrhotic patients who had previously bled from esophageal varices. When entry into the trial was terminated in 1976, 26 patients had received the distal splenorenal shunt (selective) and 29 had undergone a nonselective shunting procedure (18 interposition mesorenal, six interposition mesocaval, and five other nonselective shunts). Three operative deaths occurred in each group. Early postoperative angiography revealed preservation of hepatic portal perfusion in 14 of 16 selective patients (88%), but in only one of 20 nonselective patients (5%; p < .001). Quantitative measures of hepatic function (maximal rate of urea synthesis or MRUS and Child's score) were similar to preoperative values in the selective group but were significantly decreased in nonselective patients on the first postoperative evaluation (p < .001 for MRUS; p < .05 for Child's score). Eighty-seven per cent of selective and 81% of nonselective patients have now been followed for three to six years since surgery. Late postoperative evaluation of 29 survivors (12 selective, 17 nonselective) still shows an advantage to the selective group with respect to MRUS, Child's score, and incidence of hepatopetal portal blood flow, but differences are no longer statistically significant. However, if the seven patients with portal flow (five selective; two nonselective) are compared to the 20 with absent portal flow (seven selective; 13 nonselective), the former group has significantly higher values for MRUS (p < .05) and Child's score (p < .025). No patient with continuing portal perfusion has developed encephalopathy as compared to a 45% incidence of this complication in individuals without portal flow (p < .05). No significant differences between selective and nonselective groups have appeared with respect to total cumulative mortality (ten selective; 38%; eight nonselective, 28%), shunt occlusion (two selective, 10%; five nonselective, 18%), or recurrent variceal hemorrhage (one selective, 4%; two nonselective, 8%). Overall, significantly fewer selective patients have developed postoperative encephalopathy (three selective, 12%; 15 nonselective, 52%; p < .001). Therefore, we conclude that the distal splenorenal shunt, especially when its objective of maintaining hepatic portal perfusion is achieved, results in significantly less morbidity than nonselective shunting procedures.