Splanchnic vein thrombosis in candidates for liver transplantation: usefulness of screening and anticoagulation

Hepatic endothelial dysfunction and abnormal angiogenesis: new targets in the treatment of portal hypertension

Portal hypertension is the main cause of complications in patients with chronic liver disease. Over the past 25 years, progress in the understanding of the pathophysiology of portal hypertension was followed by the introduction of an effective pharmacological therapy, consisting mainly of treatments aimed at correcting the increased splanchnic blood flow. It is only recently that this paradigm has been changed. Progress in our knowledge of the mechanisms of increased resistance to portal blood flow, of the formation of portal-systemic collaterals, and of mechanisms other than vasodilatation maintaining the increased splanchnic blood flow have opened entirely new perspectives for developing more effective treatment strategies. This is the aim of the current review, which focuses on: (a) the modulation of hepatic vascular resistance by correcting the increased hepatic vascular tone due to hepatic endothelial dysfunction, and (b) correcting the abnormal angiogenesis associated with portal hypertension, which contributes to liver inflammation and fibrogenesis, to the hyperkinetic splanchnic circulation, and to the formation of portal-systemic collaterals and varices.

Hemostasis and thrombosis in patients with liver disease: the ups and downs

Patients with chronic or acute liver failure frequently show profound abnormalities in their hemostatic system. Whereas routine laboratory tests of hemostasis suggest these hemostatic alterations result in a bleeding diathesis, accumulating evidence from both clinical and laboratory studies suggest that the situation is more complex. The average patient with liver failure may be in hemostatic balance despite prolonged routine coagulation tests, since both pro- and antihemostatic factors are affected, the latter of which are not well reflected in routine coagulation testing. However, this balance may easily tip towards a hypo- or hypercoagulable situation. Indeed, patients with liver disease may encounter both hemostasis-related bleeding episodes as well as thrombotic events. During the 3rd International Symposium on Coagulopathy and Liver disease, held in Groningen, The Netherlands (18-19 September 2009), a multidisciplinary panel of experts critically reviewed the current data concerning pathophysiology and clinical consequences of hemostatic disorders in patients with liver disease. Highlights of this symposium are summarized in this review.

Detection of the imbalance of procoagulant versus anticoagulant factors in cirrhosis by a simple laboratory method

Patients with cirrhosis possess an imbalance in procoagulant versus anticoagulant activity due to increased factor VIII and decreased protein C. This imbalance can be detected by thrombin-generation assays performed in the presence/absence of thrombomodulin (predicate assay) that are not readily available in clinical laboratories. We sought to assess this hypercoagulability with a simpler thrombin-generation assay performed in the presence/absence of Protac, a snake venom that activates protein C in a manner similar to thrombomodulin (new assay). We analyzed blood from 105 patients with cirrhosis and 105 healthy subjects (controls). Results for the predicate-assay or the new-assay were expressed as ratio (with:without thrombomodulin) or as Protac-induced coagulation inhibition (PICI%). By definition, high ratios or low PICI% translate into hypercoagulability. The median(range) PICI% was lower in patients (74% [31%-97%]) than controls (93% [72%-99%]; P < 0.001), indicating that patients with cirrhosis are resistant to the action of Protac. This resistance resulted in greater plasma hypercoagulability in patients who were Child class C than those who were A or B. The hypercoagulability of Child C cirrhosis (63% [31%-92%]) was similar to that observed for patients with factor V Leiden (69% [15%-80%]; P = 0.59). The PICI% values were correlated with the levels of protein C (rho = 0.728, P < 0.001) or factor VIII (rho = -0.517, P < 0.001). Finally, the PICI% values were correlated with the predicate assay (rho = -0.580, P < 0.001).

CONCLUSION

The hypercoagulability of plasma from patients with cirrhosis can be detected with the new assay, which compares favorably with the other markers of hypercoagulability (i.e., high factor VIII and low protein C) and with the predicate-assay based on thrombin-generation with/without thrombomodulin. Advantages of the new assay over the predicate assay are easy performance and standardized results. Prospective trials are needed to ascertain whether it is useful to predict thrombosis in patients with cirrhosis.

Safety and efficacy of anticoagulation therapy with low molecular weight heparin for portal vein thrombosis in patients with liver cirrhosis

BACKGROUND

Treatment of portal vein thrombosis (PVT) in patients with liver cirrhosis is not well established.

AIM

We intended to assess the safety and efficacy of low molecular weight heparin (LMWH) to treat PVT in cirrhotic patients.

STUDY

All 39 patients diagnosed with non-neoplastic PVT and cirrhosis from June 2005 to December 2006 were evaluated for anticoagulation therapy (AT). PVT was occludent in 15.4%, partial in 64.1%, and portal cavernoma presented in 20.5%. Twenty-eight patients received 200 U/kg/d of enoxaparin for at least 6 months. In 39.3% of patients PVT was an occasional finding, in 10.7% presented with acute abdominal pain, in 50% with bleeding from gastroesophageal varices. In this last group LMWH was started after endoscopic eradication of varices by band ligation.

RESULTS

Complete recanalization of portal vein occurred in 33.3%, partial recanalization in 50% and no response in 16.7% of patients. Further 12 patients who continued AT obtained complete recanalization at a median time of 11 months (range 7 to 17 mo). Overall, a complete response was obtained in 75% of patients. No significant side effects, particularly bleeding complications, were observed during the treatment.

CONCLUSIONS

LMWH demonstrated safe and effective in the treatment of PVT in patients with liver cirrhosis.

Systemic thrombolysis of portal vein thrombosis in cirrhotic patients: a pilot study

BACKGROUND

Portal vein thrombosis is a frequent complication in liver cirrhosis. Encouraging reports of systemic thrombolysis in non-cirrhotic patients suffering from acute portal vein thrombosis led us to start a pilot study on the efficacy and safety of systemic low dose recombinant tissue plasminogen activator (Actilyse, Boheringer Ingelheim, Florence, Italy).

PATIENTS

Nine cirrhotic patients (6 males and 3 females) with recent portal vein thrombosis were enrolled. Exclusion criteria were portal cavernomatosis, recent (30 days) surgery, active bleeding, hepatocellular carcinoma and cancer in other sites.

METHODS

All cases were treated for a maximum of 7 days by continuous i.v. infusion of 0.25mg/kg/die of r-tPA plus subcutaneous low molecular weight heparin. Efficacy was evaluated by colour doppler sonography monitoring and confirmed by contrast enhanced computerized tomography.

RESULTS

The combined r-tPA/LMWH treatment was well tolerated without clinically significant side effects. Complete resolution of thrombosis occurred in 4 cases, partial regression in 4 and none in 1. Retreatment of a complete recurrence in 1 patient was successful. Variceal pressure dropped from 30.7+/-4.5 mmHg to 21.2+/-6.6 mmHg (p=0.012).

CONCLUSIONS

Our preliminary data demonstrate that thrombolytic treatment of recent portal vein thrombosis with i.v. r-tPA and LMWH in patients with cirrhosis appears to be safe and effective and can significantly reduce pressure in oesophageal varices.

Portal vein thrombosis, revisited

This review article aims to discuss the aetiology, pathophysiology, clinical presentation, diagnostic workup and management of portal vein thrombosis, either as a primary vascular liver disease in adults and children, or as a complication of liver cirrhosis. In addition, indications and limits of anticoagulant therapy are discussed in detail.

Survival among children with portal vein thrombosis and end-stage liver disease

Occlusive PVT concurrent with chronic liver disease is a common clinical entity among pediatric patients referred for transplantation. The natural history of PVT is unknown. Our aim was to determine, using a retrospective cohort design, if children under 13 yr with chronic liver disease and concomitant PVT have an increased mortality risk prior to and after transplantation. A total of 203 patients were included in the study. Nearly 10% of the population had PVT (n = 19); 63.2% of PVT patients (5.9% of total cohort) underwent liver transplantation (n = 12). PVT patients tended to be younger than non-PVT patients at evaluation (1.94 +/- 3.51 vs. 3.79 +/- 4.11, p = 0.059). Clinical and demographic factors were similar between the two groups. Regarding survival, four PVT patients died, of which two had undergone transplantation. Kaplan-Meier analyses indicated that PVT and non-PVT patients had similar survival from the time of evaluation, on the waiting list, and after transplant. Although limited by sample size, our study suggests that a diagnosis of PVT does not increase the mortality risk for children waiting for a liver transplant. Further study is needed to discern variations in mortality risk that may occur in the pediatric chronic liver disease population with PVT.

Systematic review: portal vein thrombosis in cirrhosis

BACKGROUND

As current imaging techniques in cirrhosis allow detection of asymptomatic portal vein thrombosis during routine ultrasonography, more patients with cirrhosis are diagnosed with portal vein thrombosis. Although a consensus on noncirrhotic extra-hepatic portal vein thrombosis has been published, no such consensus exists for portal vein thrombosis with cirrhosis.

AIM

To perform a systematic review of nonmalignant portal vein thrombosis in cirrhosis in terms of prevalence, pathogenesis, diagnosis, clinical course and management.

METHODS

Studies were identified by a search strategy using MEDLINE and EMBASE.

RESULTS

Portal vein thrombosis is encountered in 10-25% of cirrhotics. In terms of pathophysiology, cirrhosis is no longer considered a hypocoagulable state; rather than a bleeding risk in cirrhosis, various clinical studies support a thrombotic potential. Clinical findings of portal vein thrombosis in cirrhosis vary from asymptomatic disease to a life-threatening condition at first presentation. Optimal management of portal vein thrombosis in cirrhosis is currently not addressed in any consensus publication. Treatment strategies most often include the use of anticoagulation, while thrombectomy and transjugular intrahepatic portosystemic shunts are considered second-line options.

CONCLUSIONS

Portal vein thrombosis in cirrhosis has many unresolved issues, which are often the critical problems clinicians encounter in their everyday practice. We propose a possible research agenda to address these unresolved issues.

Portal vein thrombosis: insight into physiopathology, diagnosis, and treatment

Portal vein thrombosis (PVT) is a relatively common complication in patients with liver cirrhosis, but might also occur in absence of an overt liver disease. Several causes, either local or systemic, might play an important role in PVT pathogenesis. Frequently, more than one risk factor could be identified; however, occasionally no single factor is discernable. Clinical examination, laboratory investigations, and imaging are helpful to provide a quick diagnosis, as prompt treatment might greatly affect a patient's outcome. In this review, we analyze the physiopathological mechanisms of PVT development, together with the hemodynamic and functional alterations related to this condition. Moreover, we describe the principal factors most frequently involved in PVT development and the recent knowledge concerning diagnostic and therapeutic procedures. Finally, we analyze the implications of PVT in the setting of liver transplantation and its possible influence on patients' future prognoses.

Impact of antithrombin III concentrates on portal vein thrombosis after splenectomy in patients with liver cirrhosis and hypersplenism

OBJECTIVE

The aim of this study was to determine the role of antithrombin III (AT-III) in portal vein thrombosis (PVT) after splenectomy in cirrhotic patients.

SUMMARY BACKGROUND DATA

There is no standard treatment for PVT after splenectomy in liver cirrhosis.

METHODS

A total of 50 consecutive cirrhotic patients who underwent laparoscopic splenectomy for hypersplenism were enrolled into this study. From January 2005 to December 2005, 25 cirrhotic patients received no prophylactic anticoagulation therapy after the operation (AT-III [-] group). From January 2006 to July 2006, 25 cirrhotic patients received prophylactic administration of AT-III concentrates (1500 U/d) on postoperative day (POD) 1, 2, and 3 (AT-III [+] group).

RESULTS

In AT-III (-) group, 9 (36.0%) patients developed PVT up to POD 7, and risk factors for PVT were identified as: low platelet counts, low AT-III activity, and increased spleen weight. Although there were no significant differences in the clinical characteristics, including the above risk factors, between the 2 groups, only 1 (4.0%) patient developed PVT on POD 30 in AT-III (+) group, and the incidence of PVT was significantly lower than in AT-III (-) group (P = 0.01). In AT-III (-) group, AT-III activity was significantly decreased from POD 1 to POD 7, as compared with the preoperative level, whereas AT-III concentrates prevented the postoperative decrease in AT-III activity.

CONCLUSIONS

These results demonstrate that low AT-III activity and further decreases in this activity are associated with PVT after splenectomy in cirrhotic patients, and that treatment with AT-III concentrates is likely to prevent the development of PVT in these patients.

Protein C and D-dimer are related to portal vein thrombosis in patients with liver cirrhosis

BACKGROUND AND AIM

To profile changes of coagulation, anticoagulation and fibrolytic factors associated with liver function failure and portal vein thrombosis (PVT) formation in chronic liver cirrhosis patients.

METHODS

A total of 116 cirrhotic patients admitted to our hospital from June 2006 to October 2008 were included in our study. All patients were classified into two groups: PVT group (31 patients), composed of patients with PVT and a control group (85 patients), including patients without PVT. Platelet, prothrombin time (PT), activated partial prothrombin time (APTT) and fibrinogen were measured. Also, plasma samples from the patients were analyzed for the levels of antithrombin III (AT-III), protein C (PC), protein S (PS), D-dimer, tissue-type plasminogen activator as well as plasminogen activator inhibitor-1. Statistical analyses were carried out to evaluate the correlation of specific variations with the disease status.

RESULTS

In general, the higher Child-Pugh scores, indicating the aggravation of hepatic impairment of the patients, correlated well with the prolonged PT/APTT and increased D-dimer, as well as decreased platelet, fibrinogen, PC and AT-III levels in the serum. Furthermore, we found that the PC, PS and D-dimer levels in PVT patients were 2.32 +/- 0.72 mg/L, 17.14 +/- 3.62 mg/L and 0.99 +/- 0.36 mg/L, respectively, both representing a significant difference compared with those in the control group without PVT. Logistic regression model shows that the odds ratio value of one unit of increase of PC and D-dimer were 0.48 and 15.57.

CONCLUSIONS

Cirrhotic patients displayed dysfunctions in the coagulation, anti-coagulation and fibrolytic systems. The development of PVT in these patients may be independently associated with the decrease of PC, PS and D-dimer. Furthermore, decreasing PC and increasing D-dimer may be risk factors inducing PVT in cirrhotic patients.

An imbalance of pro- vs anti-coagulation factors in plasma from patients with cirrhosis

BACKGROUND & AIMS

Patients with cirrhosis have an increased tendency to develop thromboses despite the longer coagulation times of their plasma, compared with that of healthy individuals. We investigated whether plasma from cirrhotic patients has an imbalance of pro- vs anti-coagulation factors.

METHODS

We analyzed blood samples from 134 cirrhotic patients and 131 healthy subjects (controls) for levels of pro- and anti-coagulants and for thrombin generation in the presence or absence of thrombomodulin (the main physiologic activator of the protein C anticoagulant pathway).

RESULTS

The median ratio of thrombin generation (with/without thrombomodulin) was higher in patients (0.80; range, 0.51-1.06) than controls (0.66; range, 0.17-0.95), indicating that cirrhotic patients are resistant to the action of thrombomodulin. This resistance resulted in greater hypercoagulability of plasma from patients of Child-Pugh class C than of class A or B. The hypercoagulability of plasma from patients of Child-Pugh class C (0.86; range, 0.70-1.06) was slightly greater than that observed under the same conditions in patients with congenital protein C deficiency (0.76; range, 0.60-0.93). Levels of factor VIII, a potent pro-coagulant involved in thrombin generation, increased progressively with Child-Pugh score (from Child-Pugh class A to C). Levels of protein C, one of the most potent naturally occurring anti-coagulants, showed the opposite trend.

CONCLUSIONS

The hypercoagulability of plasma from patients with cirrhosis appears to result from increased levels of factor VIII and decreased levels of protein C-typical features of patients with cirrhosis. These findings might explain the risk for venous thromboembolism in patients with chronic liver disease.

Severe sepsis in cirrhosis

Sepsis is physiologically viewed as a proinflammatory and procoagulant response to invading pathogens. There are three recognized stages in the inflammatory response with progressively increased risk of end-organ failure and death: sepsis, severe sepsis, and septic shock. Patients with cirrhosis are prone to develop sepsis, sepsis-induced organ failure, and death. There is evidence that in cirrhosis, sepsis is accompanied by a markedly imbalanced cytokine response ("cytokine storm"), which converts responses that are normally beneficial for fighting infections into excessive, damaging inflammation. Molecular mechanisms for this excessive proinflammatory response are poorly understood. In patients with cirrhosis and severe sepsis, high production of proinflammatory cytokines seems to play a role in the worsening of liver function and the development of organ/system failures such as shock, renal failure, acute lung injury or acute respiratory distress syndrome, coagulopathy, or hepatic encephalopathy. In addition, these patients may have sepsis-induced hyperglycemia, defective arginine-vasopressin secretion, adrenal insufficiency, or compartmental syndrome. In patients with cirrhosis and spontaneous bacterial peritonitis (SBP), early use of antibiotics and intravenous albumin administration decreases the risk for developing renal failure and improves survival. There are no randomized studies that have been specifically performed in patients with cirrhosis and severe sepsis to evaluate treatments that have been shown to improve outcome in patients without cirrhosis who have severe sepsis or septic shock. These treatments include recombinant human activated C protein and protective-ventilation strategy for respiratory failure. Other treatments should be evaluated in the cirrhotic population with severe sepsis including the early use of antibiotics in "non-SBP" infections, vasopressor therapy, hydrocortisone, renal-replacement therapy and liver support systems, and selective decontamination of the digestive tract or oropharynx.

Management of portal vein thrombosis in cirrhotic patients

Portal vein thrombosis (PVT) not associated with hepatocellular carcinoma is considered a frequent complication of liver cirrhosis but, unlike PVT occurring in non-cirrhotic patients, very few data are available on its natural history and management. The reduced portal blood flow velocity is the main determinant of PVT but, as in other venous thromboses, multiple factors local and systemic, inherited or acquired often can concur with. PVT has a variety of clinical presentations ranging from asymptomatic to life-threatening diseases like gastroesophageal bleeding or acute intestinal ischemia. It is usually diagnosed by Doppler ultrasound but computed tomography and magnetic resonance imaging are useful to study the extent of thrombosis and the involvement of the abdominal organs. The risk of bleeding mainly determined by the presence of gastroesophageal varices and clotting alterations causes concern for the treatment of PVT in cirrhotic patients. To date, anticoagulant therapy seems to be indicated only in patients awaiting liver transplantation. This review focuses on the definition of the subgroups of patients with cirrhosis that might benefit from treatment of PVT and examines the pros and cons of the available treatments in terms of efficacy, monitoring and safety, providing also perspectives for future studies.

Review article: the modern management of portal vein thrombosis

BACKGROUND

Portal vein thrombosis (PVT) is an important cause of portal hypertension. It may occur as such with or without associated cirrhosis and hepatocellular carcinoma. Information on its management is scanty.

AIM

To provide an update on the modern management of portal vein thrombosis. Information on portal vein thrombosis in patients with and without cirrhosis and hepatocellular carcinoma is also updated.

METHODS

A pubmed search was performed to identify the literature using search items portal vein thrombosis-aetiology and treatment and portal vein thrombosis in cirrhosis and hepatocellular carcinoma.

RESULTS

Portal vein thrombosis occurs because of local inflammatory conditions in the abdomen and prothrombotic factors. Acute portal vein thrombosis is usually symptomatic when associated with cirrhosis and/or superior mesenteric vein thrombosis. Anticoagulation should be given for 3-6 months if detected early. If prothrombotic factors are identified, anticoagulation should be given lifelong. Chronic portal vein thrombosis usually presents with well tolerated upper gastrointestinal bleed. It is diagnosed by imaging, which demonstrates a portal cavernoma in place of a portal vein. Anticoagulation does not have a definite role, but bleeds can be treated with endotherapy or shunt surgery. Rarely liver transplantation may be considered.

CONCLUSION

Role of anticoagulation in chronic portal vein thrombosis needs to be further studied.

Thrombotic risk factors in patients with liver cirrhosis: correlation with MELD scoring system and portal vein thrombosis development

BACKGROUND/AIMS

Prognostic scores currently used in cirrhotic patients do not include thrombotic risk factors (TRFs). Predicting factors of portal vein thrombosis (PVT) development are still unknown. We wanted to describe TRFs as a function of liver disease severity using the MELD score and assess the role of local and systemic TRFs as predictors of PVT development in cirrhotic patients.

METHODS

One hundred consecutive patients with liver cirrhosis were included in the study. TRFs, D-dimers, MELD score, portal vein patency and flow velocity were evaluated in all subjects at baseline and every 6 months thereafter. Variables able to predict PVT development within 1 year were identified by means of multiple logistic regression.

RESULTS

The plasma levels of protein C and antithrombin were lower and the concentration of D-dimers was higher in patients with advanced disease. Plasma levels of antithrombin, protein C and protein S resulted significantly lower in PVT group at univariate analysis, but reduced portal vein flow velocity was the only variable independently associated with PVT development.

CONCLUSIONS

Lower concentrations of natural coagulation inhibitors are frequently detected in patients with liver cirrhosis. A reduced portal flow velocity seems to be the most important predictive variable for PVT development in patients with cirrhosis.

Should we give thromboprophylaxis to patients with liver cirrhosis and coagulopathy?

Patients with liver cirrhosis are characterized by decreased synthesis of both pro- and anticoagulant factors, and recently there has been evidence of normal generation of thrombin resulting in a near normal haemostatic balance. Although it is generally recognized that bleeding is the most common clinical manifestation as a result of decreased platelet function and number, diminished clotting factors and excessive fibrinolysis, hypercoagulability may play an under recognized but important role in many aspects of chronic liver disease. In fact, they can encounter thrombotic complications such as portal vein thrombosis, occlusion of small intrahepatic vein branches and deep vein thrombosis (DVT). In particular, patients with cirrhosis appear to have a higher incidence of unprovoked DVT and pulmonary embolism (PE) compared with the general population. In dedicated studies, the incidence of DVT/PE ranges from 0.5% to 1.9%, similar to patients without comorbidities, but lower than patients with other chronic diseases (i.e, renal or heart disease). Surprisingly, standard coagulation laboratory parameters are not associated with a risk of developing DVT/PE; however, with multivariate analysis, serum albumin level was independently associated with the occurrence of thrombosis. Moreover, patients with chronic liver disease share the same risk factors as the general population for DVT/PE, and specifically, liver resection can unbalance the haemostatic equilibrium towards a hypercoagulable state. Current guidelines on antithrombotic prophylaxis do not specifically comment on the cirrhotic population as a result of the perceived risk of bleeding complications but the cirrhotic patient should not be considered as an auto-anticoagulated patient. Therefore, thromboprophylaxis should be recommended in patients with liver cirrhosis at least when exposed to high-risk conditions for thrombotic complications. Low molecular weight heparins (LWMHs) seem to be relatively safe in this group of patients; however, when important risk factors for bleeding are present, graduated compression stockings or intermittent pneumatic compression should be considered.

Adult to pediatric living donor liver transplantation for portal cavernoma

AIM

Portal cavernoma (PC) is an important cause of non-cirrhotic portal hypertension with severe complications, such as variceal hemorrhage in pediatric patients. With the development of new surgical techniques, living donor liver transplantation (LDLT) has recently been recognized as a viable but challenging treatment option for PC. The purpose of the present study was to summarize the efficacy of LDLT in PC patients and to carry out a follow-up study of pediatric recipients.

METHODS

The primary indication for LDLT in our research was PC with severe variceal bleeding and liver function decompensation. Three patients were diagnosed with PC following evaluation with computed tomography angiography and abdominal color Doppler ultrasonography (CDU).

RESULTS

Various surgical techniques, including jump bypass grafting for portal vein anastomosis, were carried out according to the range and degree of cavernous transformation within the splenic vein and superior mesenteric vein. Postoperative CDU confirmed the early integrity of the portal vein (PV) in each patient. PV rethrombosis occurred in one patient 7 days after LDLT, despite anticoagulation therapy with coumadin. Two of the three patients had no further episodes of variceal hemorrhage during the 2-year follow-up period.

CONCLUSIONS

The present study is the first report of the successful use of LDLT to treat pediatric PC patients. We conclude that LDLT is effective for the majority of pediatric patients with PC.

Application of cryopreserved vein grafts as a conduit between the coronary vein and liver graft to reconstruct portal flow in adult living liver transplantation

Adult-to-adult living donor liver transplantation is an alternative to donation from a deceased individual, and can help relieve the shortage of liver donations available for adult patients in Asian countries. When transplant candidates have thrombosis and deterioration of the portal vein, living donor liver transplantation is relatively contraindicated because portal veins in the grafts are short and vein grafts may not be available to reconstruct the portal vein. From June 2003 to May 2007, 82 adult living donor liver transplantations were performed at Chang-Gung Memorial Hospital. Three patients had portal vein thrombosis and marked fibrosis of the portal vein and cryopreserved vein grafts were used to reconstruct portal flow from the engorged coronary vein to the graft portal vein. All vein grafts are patent and all patients have normal liver function at 21-36 months after transplantation. When cryopreserved vein grafts are available, adult living donor liver transplantation can be successfully performed in patients with marked deterioration of the portal vein. The short distance from the engorged coronary vein to the graft portal vein may decrease the incidence of re-thrombosis of the venous conduit.

Long-term survival after portal vein arterialization for portal vein thrombosis in orthotopic liver transplantation

Portal vein thrombosis is a relatively common finding during liver transplantation. The management of portal vein thrombosis during liver transplantation is technically demanding and ensures adequate portal flow to the liver graft. Eversion thromboendovenectomy and bypass using a patent splanchnic vein and cavoportal hemitransposition are the most often used procedures to treat portal vein thrombosis. There have been anecdotal reports of portal vein arterialization. We report a case of portal vein arterialization during orthotopic liver transplantation for decompensated cirrhosis. When thromboendovenectomy failed to restore sufficient portal flow and completion of arterial anastomosis between the recipient hepatic artery and the donor celiac trunk, a calibrated end-to-side anastomosis between the donor splenic artery and the donor portal vein was performed. With a 6-year follow-up, there are no symptoms related to portal hypertension, liver function is normal. However, an aneurismal dilatation of the portal branches has progressively developed. Calibrated portal vein arterialization is a possible option for portal vein thrombosis in liver transplantation, allowing long-term patient and graft survival.

Vascular disorders of the liver

This guideline has been approved by the American Association for the Study of Liver Diseases (AASLD) and represents the position of the association.

Portal vein thrombosis and budd-Chiari syndrome

Venous thrombosis results from the convergence of vessel wall injury and/or venous stasis, known as local triggering factors, and the occurrence of acquired and/or inherited thrombophilia, also known as systemic prothrombotic risk factors. Portal vein thrombosis (PVT) and Budd-Chiari syndrome (BCS) are caused by thrombosis and/or obstruction of the extrahepatic portal veins and the hepatic venous outflow tract, respectively. Several divergent prothrombotic disorders may underlie these distinct forms of large vessel thrombosis. While cirrhotic PVT is relatively common, especially in advanced liver disease, noncirrhotic and nontumoral PVT is rare and BCS is of intermediate incidence. In this article, we review pathogenic mechanisms and current concepts of patient management.

Portal vein thrombosis in liver cirrhosis

Portal vein thrombosis (PVT) is observed in 10-20% of patients with liver cirrhosis, which is responsible for 20% of all PVT cases. The main pathogenic factor of PVT in cirrhosis is the obstacle to portal flow, but acquired and inherited clotting abnormalities may play a role. The formation of collateral veins allows many patients to remain asymptomatic and prevents the onset of clinical complications also in patients with totally occlusive PVT. Gastrointestinal bleeding, thrombosis of superior mesenteric vein and refractory ascites are typical manifestations of PVT. Instrumental diagnosis can be obtained by colour-doppler ultrasonography. Future studies should verify whether asymptomatic PVT worsens liver failure, or if its life-threatening complications reduce survival in patients with cirrhosis. Moreover, randomized controlled trials should clarify the potential effectiveness of anticoagulant therapy in the treatment of PVT.

Endoscopic band ligation of esophageal varices in patients on anticoagulation

Endoscopic band ligation is an effective technique for primary and secondary prevention of gastro-esophageal variceal bleeding (GEVB), but can also result in rebleeding from postbanding ulcers. Its use in primary and secondary prevention of GEVB in anticoagulated patients has not been systematically studied. The aim of the study was to evaluate the feasibility of band ligation in primary and secondary prevention of GEVB in anticoagulated patients. Five patients (age 60.2+/-7.3 SD years: 3 males, 2 females) with esophageal varices on anticoagulation were studied using a retrospective chart review in a tertiary hospital setting. Patients were on mandatory anticoagulation with warfarin (international normalized ratio >2), on nonselective beta-blocker therapy if tolerated and were not transvenous intrahepatic porto-systemic shunting candidates. One patient had polycythemia vera (noncirrhotic), the rest were cirrhotics Child class B/C (1 cardiogenic, 1 primary sclerosing cholangitis, 1 Budd-Chiari, and 1 cryptogenic cirrhosis). Two patients had experienced prior acute GEVB; band ligation performed during acute bleeding was not included in the study. All patients had at least grade III-IV esophageal varices on outpatient follow-up for band ligation. Three bands were placed/patient and study patients underwent 3 banding sessions on an average. None of the patients developed GEVB after band ligation. In 3 patients banding resulted in complete variceal eradication, the remaining 2 are still being followed-up for outpatient band ligation. In conclusion, this case series suggests that endoscopic band ligation can potentially be used in anticoagulated patients without alternatives for prevention of acute GEVB.

Chronic oral anticoagulant therapy for extrahepatic visceral thrombosis is safe

BACKGROUND

Patients with hypercoagulability may thrombose visceral veins with resultant portal hypertension, esophagogastric varices, and hemorrhage. The role of chronic oral anticoagulant therapy in such patients is unclear. On the one hand, such patients are prone to significant hemorrhage and thus anticoagulant therapy may seem contraindicated. On the other hand, because the causal pathophysiology is typically hypercoagulability, it would seem rational to treat these patients with chronic anticoagulant therapy in order to both prevent other visceral and systemic thromboses and perhaps, over time, reduce the degree of portal hypertension. Experience and poor prognosis associated with the more common portal hypertension due to hepatic cirrhosis may bias judgment.

METHODS

We retrospectively reviewed the course of chronic oral anticoagulant therapy regarding both the safety and effectiveness using our long-term follow-up of a cohort of seven patients with visceral thrombosis resulting in extrahepatic non-cirrhotic portal hypertension.

RESULTS

Seven consecutive patients encountered over the past 19 years were observed for 78 patient-years, the first 14 patient-years prior to anticoagulant therapy and the latter 64 patient-years on oral anticoagulant therapy. No patients rethrombosed either visceral or systemic vessels while on oral anticoagulant therapy. There were no fatal or serious hemorrhagic events on oral anticoagulant therapy; in fact, upper gastrointestinal bleeding decreased from 1.2 to 0.2 bleeds/year. The endoscopic grade of esophageal varices decreased in four of five patients who underwent serial endoscopy, and platelet counts increased in all seven patients.

CONCLUSIONS

Chronic oral anticoagulant therapy is safe and not associated with an increase in upper gastrointestinal bleeding in such patients. Additionally, and by inference, perhaps in conjunction with the natural history of portal hypertension, such therapy is possibly effective in reducing portal hypertension in patients with hypercoagulability-induced extrahepatic portal hypertension.

Thrombosis of the portal venous system

Portal vein thrombosis (PVT) is a rare cause of portal hypertension. Its diagnosis has been facilitated by improvements in imaging techniques, in particular Doppler sonography. The prevalence is about 1% in the general population, but much higher rates are observed in patients with hepatic cirrhosis (7%, range 0.6-17%), particularly those who also have hepatocellular carcinoma (HCC) (35%). The most common causes of PVT are myeloproliferative disorders, deficiencies of anticoagulant proteins, prothrombotic gene mutations, cirrhosis with portal hypertension, and HCC. Its development often requires the presence of two or more risk factors (local and/or systemic), e.g., a genetically determined thrombophilic state plus an infectious episode or abdominal surgery. It is clinically useful to distinguish between cirrhotic and noncirrhotic forms. Portal vein thrombosis is also traditionally classified as acute or chronic, but this distinction is often difficult. Color Doppler ultrasound is the first-line imaging study for diagnosis of PVT; magnetic resonance angiography and CT angiography are valid alternatives. The main complications are ischemic intestinal necrosis (in acute PVT) and esophageal varices (in chronic cases); the natural history of the latter differs depending on whether or not the thrombosis is associated with cirrhosis. The treatment of choice for PVT has never been adequately investigated. It is currently based on the use of anticoagulants associated, in some cases, with thrombolytics, but experience with the latter agents is too limited to draw any definite conclusions. In chronic thrombosis (even forms associated with cirrhosis), anticoagulant therapy is recommended and possibly, beta-blockers as well. Naturally, treatment of the underlying pathology is essential.

The use of carbon dioxide wedged hepatic venography to identify the portal vein: comparison with direct catheter portography with iodinated contrast medium and analysis of predictive factors influencing level of opacification

PURPOSE

This study was conducted to assess the value of wedged hepatic venography (WHV) with CO(2) as a contrast agent for identification of the portal venous system in patients with cirrhosis. Additionally, the predictive value of several parameters that potentially influence the level of portal vein opacification by CO(2) WHV was analyzed.

MATERIALS AND METHODS

In 163 patients, CO(2) WHV was performed before transjugular intrahepatic portosystemic shunt creation to opacify and map the portal vein for subsequent targeting by intrahepatic puncture technique. Concordance between CO(2) WHV and direct catheter portography with iodinated contrast medium was assessed by analysis of sensitivity parameters. Additionally, analysis of factors potentially influencing the opacification of the portal vein with use of CO(2) WHV was assessed.

RESULTS

CO(2) WHV was successfully performed in all 163 patients. In three patients (1.8%), CO(2) extravasation was noted, but without any clinical consequence. Sensitivity rates of CO(2) WHV for opacification of the right and left portal veins and the portal main trunk were 93.83% and 68.52%, respectively. Positive predictive factors (P < .05, Wilcoxon two-sample test) were high portosystemic gradient, spontaneous splenorenal shunt, esophageal varices, and reversed portal flow. One negative predictive factor was a patent umbilical vein.

CONCLUSIONS

CO(2) WHV is safe, highly efficient, and reliable in the identification of the right and left portal veins. CO(2) WHV is clearly less effective in opacifying the entire portal main trunk. With use of CO(2) WHV, the portal venous system is most distinctly opacified in patients presenting with a high portosystemic gradient, a spontaneous splenorenal shunt, esophageal varices, and reversed portal flow.

Liver transplantation in adult patients with portal vein thrombosis: risk factors, management and outcome

BACKGROUND

Portal vein thrombosis (PVT) is a well recognized complication of patients with end-stage cirrhosis and its incidence ranges from 2 to 26%. The aim of this study was to analyze the results and long-term follow-up of a consecutive series of liver transplants performed in patients with PVT and compare them with patients transplanted without PVT.

PATIENTS AND METHODS

Between July 1995 and June 2006, 26 liver transplants were performed in patients with PVT (8.7%). Risk factors and variables associated with the transplant and the post-transplant period were analyzed. A comparative analysis with 273 patients transplanted without PVT was performed.

RESULTS

The patients comprised 53.8% males, average age 40, 7 years. PVT was detected during surgery in 65%. Indications for transplantation were: post-necrotic cirrhosis 73%, cholestatic liver diseases 23%, and congenital liver fibrosis 4%. Child-Pugh C: 61.5%. Techniques were trombectomy in 21 patients with PVT grades I, II, IV, and extra-anatomical mesenteric graft in 5 with grade III. Morbidity was 57.7%, recurrence of PVT was 7.7%, and in-hospital mortality was 26.9%. Greater operative time, transfusion requirements, and re-operations were found in PVT patients. One-year survival was 59.6%: 75.2% for grade 1 and 44.8% for grades 2, 3, and 4.

DISCUSSION

The study demonstrated a PVT prevalence of 8.7%, a higher incidence of partial thrombosis (grade 1), and successful management of PVT grade 4 with thrombectomy. Liver transplant in PVT patients was associated with an increased operative time, transfusion requirements, re-interventions, and lower survival rate according to PVT extension.

New insights into the coagulopathy of liver disease and liver transplantation

The liver is an essential player in the pathway of coagulation in both primary and secondary haemostasis. Only von Willebrand factor is not synthetised by the liver, thus liver failure is associated with impairment of coagulation. However, recently it has been shown that the delicate balance between pro and antithrombotic factors synthetised by the liver might be reset to a lower level in patients with chronic liver disease. Therefore, these patients might not be really anticoagulated in stable condition and bleeding may be caused only when additional factors, such as infections, supervene. Portal hypertension plays an important role in coagulopathy in liver disease, reducing the number of circulating platelets, but platelet function and secretion of thrombopoietin have been also shown to be impaired in patients with liver disease. Vitamin K deficiency may coexist, so that abnormal clotting factors are produced due to lack of gamma carboxylation. Moreover during liver failure, there is a reduced capacity to clear activated haemostatic proteins and protein inhibitor complexes from the circulation. Usually therapy for coagulation disorders in liver disease is needed only during bleeding or before invasive procedures. When end stage liver disease occurs, liver transplantation is the only treatment available, which can restore normal haemostasis, and correct genetic clotting defects, such as haemophilia or factor V Leiden mutation. During liver transplantation haemorrage may occur due to the pre-existing hypocoagulable state, the collateral circulation caused by portal hypertension and increased fibrinolysis which occurs during this surgery.

Single center experience of 39 patients with preoperative portal vein thrombosis among 404 adult living donor liver transplantations

Living donor liver transplantation (LDLT) for patients with portal vein thrombosis (PVT) involves technical difficulty. The aim of this research was to analyze their preoperative diagnosis of PVT, operative procedures, and postoperative courses of patients with preoperative PVT. Thirty-nine patients of 404 adult patients (9.7%) undergoing LDLT in our hospital from 1996 June to 2004 December had PVT at their transplantation. Twenty-nine patients had intractable ascites, 21 had gastrointestinal bleeding, and 18 had encephalopathy. The thrombus was located in the portal trunk in 23, in the portal trunk and superior mesenteric vein (SMV) in 7, and developed into the SMV and the splenic vein in 8. The occlusive grade was partial in 29, and complete in 10 patients. The thrombus was removed by a simple technique, and eversion and/or incision technique, or total removal of the portal vein (PV). The PV was reconstructed with the thrombectomized native PV, with an interposed vein graft, or porto-caval hemitransposition. Advanced PVT had a significant impact on blood loss and hospital mortality. Three out of 10 patients with residual PVT required radiological and/or surgical intervention after transplantation. In conclusion, thorough planning is essential for a successful LDLT outcome for patients with preexisting PVT.

Nonmalignant portal vein thrombosis in adults

Portal vein thrombosis (PVT) consists of two different entities: acute PVT and chronic PVT. Acute PVT usually presents as abdominal pain. When the thrombus extends to the mesenteric venous arches, intestinal infarction can occur. Chronic PVT is usually recognized after a fortuitous diagnosis of hypersplenism or portal hypertension, or when there are biliary symptoms related to portal cholangiopathy. Local risk factors for PVT, such as an abdominal inflammatory focus, can be identified in 30% of patients with acute PVT; 70% of patients with acute and chronic PVT have a general risk factor for PVT, most commonly myeloproliferative disease. Early initiation of anticoagulation therapy for acute PVT is associated with complete and partial success in 50% and 40% of patients, respectively. A minimum of 6 months' anticoagulation therapy is recommended for the treatment of acute PVT. For patients with either form of PVT, permanent anticoagulation therapy should be considered if they have a permanent risk factor. In patients with large varices, beta-adrenergic blockade or endoscopic therapy seems to prevent bleeding as a result of portal hypertension, even in patients on anticoagulation therapy. In patients with jaundice or recurrent biliary symptoms caused by cholangiopathy, insertion of a biliary endoprosthesis is the first treatment option. Overall, the long-term outcome for patients with PVT is good, but is jeopardized by cholangiopathy and transformation of underlying myeloproliferative disease into myelofibrosis or acute leukemia.

Noncirrhotic portal vein thrombosis exhibits neuropsychological and MR changes consistent with minimal hepatic encephalopathy

Hepatic encephalopathy can arise from portal-systemic shunting in the absence of intrinsic liver disease. However, there are few descriptions of this form of encephalopathy. Portal vein thrombosis is an infrequent disease that causes portal-systemic shunting. Episodic hepatic encephalopathy has been described in patients with portal vein thrombosis, but it is not known if these patients develop minimal hepatic encephalopathy. We designed a study to investigate the neurological consequences of portal vein thrombosis in patients without cirrhosis and no clinical signs of encephalopathy. For this purpose, 10 patients underwent neuropsychological tests, an oral glutamine challenge test, and brain magnetic resonance (MR) imaging. The results were compared with those obtained in 10 healthy controls. Patients with portal vein thrombosis exhibited abnormalities in the results of neuropsychological tests, oral glutamine challenge test, and MR similar to those described in hepatic encephalopathy associated with cirrhosis. MR spectroscopy revealed a decrease in myo-inositol and an increase in glutamine. The increase in glutamine correlated with an increase in ammonia following the oral glutamine challenge test, signs of increased brain water (decrease in magnetization transfer ratio), and impairment of attention tests. In conclusion, patients with noncirrhotic portal vein thrombosis develop subclinical neurological abnormalities compatible with minimal hepatic encephalopathy. These disturbances, which include signs of increase in brain water and a compensatory osmotic response (decrease in brain myo-inositol), appear to be secondary to brain exposure to ammonia induced by portal-systemic shunting.