Portal vein thrombosis: a clinician-oriented and practical review

Safety and Efficacy of Portal Vein Recanalization with Creation of Intrahepatic Portosystemic Shunt (PVR-TIPS) to Treat Chronic Portal Vein Thrombosis in Non-cirrhotic Patients

PURPOSE

This study assesses the efficacy and safety of Portal Vein Recanalization with Intrahepatic Portosystemic Shunt (PVR-TIPS) in non-cirrhotic patients with chronic portal vein occlusion (CPVO), cavernomatous transformation, and symptomatic portal hypertension (PH) and/or portal vein thrombotic progression.

MATERIAL AND METHODS

Medical records of 21 non-cirrhotic patients with CPVO and portal cavernoma undergoing PVR-TIPS were analyzed. Hemodynamic (intraprocedural reduction in portosystemic pressure gradient), clinical (data on gastrointestinal bleeding, abdominal pain, ascites, and presence of esophageal varices from imaging exams) and technical success (PVR-TIPS) assessed efficacy. Safety was determined through complications classified according to the CIRSE Classification System.

RESULTS

PVR-TIPS was successfully performed in all patients, resulting in a significant reduction in portal pressure gradient by 10 mmHg (21.475 ± 9.7 mmHg - 11.454 ± 5,4 mmHg, p < 0.001), alleviating portal hypertension symptoms without thrombotic progression. Clinical success included resolution or reduction of ascites (p = 0.016), gastroesophageal varices (p = 0.004), abdominal pain (p = 0.0021), and cessation of gastrointestinal bleeding (p = 0.021). Complications occurred in 33% of patients, including six grade III events (1 perioperative liver bleeding, 5 delayed stent occlusions) and one grade VI event resulting in death (4.8%). Primary patency rate was 76% (21.3 months, range:0.2-82), secondary patency 100% (4 months, range:3.8-40.8). Survival at follow-up was 90.4%, with one unrelated death. One patient underwent liver transplantation, three became eligible post-recanalization.

CONCLUSION

PVR-TIPS proves effective and safe in reducing portal pressure gradient, thereby alleviating PH symptoms without evidence of portal thrombosis progression in non-cirrhotic patients with CPVO and portal cavernoma. It expands therapeutic options, including liver transplantation.

Therapeutic anticoagulation in patients with acute pancreatitis and splanchnic vein thrombosis: a best evidence topic

A best evidence topic in general surgery was written according to a structured protocol. The clinical question addressed was: in adult patients with splanchnic vein thrombosis in acute pancreatitis, would administration of therapeutic anticoagulation be advisable considering the rates of vessel recanalization and bleeding complications? Four hundred twenty-four papers were found on Ovid Embase and Medline whilst 222 were found on PubMed using the reported literature search. From these, five articles represented the best evidence to the clinical question. The authors, publication dates, countries, patient groups, study outcomes, and results of these papers were tabulated. There were three systematic reviews with meta-analyses, one systematic review without meta-analysis and one randomized, retrospective study. The authors conclude that among patients with splanchnic vein thrombosis in the context of acute pancreatitis, therapeutic anticoagulation improved the rates of recanalization without increasing the risk of bleeding complications. However, there remains a need for randomized studies to address this clinical dilemma to further increase the quality of available evidence.

Recanalization of Portal Vein Graft Occlusion via a Percutaneous Transmesenteric Approach: A Case Report

Interventional recanalization is an effective treatment option for postoperative portal vein occlusion. A transhepatic or transsplenic approach is preferred, whereas a percutaneous transmesenteric route enables antegrade cannulation. Here, we present a case of successful percutaneous transmesenteric recanalization in a patient with a postoperative portal vein graft occlusion.

COVID-19-Associated Portal Vein Thrombosis Post-Cholecystitis

This case study describes a 45-year-old Caucasian male with a past medical history of obesity, hypertension, and non-insulin-dependent diabetes mellitus, who in the setting of coronavirus disease 2019 (COVID-19) pneumonia, developed portal vein thrombosis (PVT) presenting as an acute abdomen after hospital discharge from a cholecystitis episode. PVT is a very infrequent thromboembolic condition, classically occurring in patients with systemic conditions such as cirrhosis, malignancy, pancreatitis, diverticulitis, autoimmunity, and thrombophilia. PVT can cause serious complications, such as intestinal infarction, or even death, if not promptly treated. Due to the limited number of reports in the literature describing PVT in the COVID-19 setting, its prevalence, natural history, mechanism, and precise clinical features remain unknown. Therefore, clinical suspicion should be high for PVT, in any COVID-19 patient who presents with abdominal pain or associated signs and symptoms. To the best of our knowledge, this is the first report of COVID-19-associated PVT causing extensive thrombosis in the portal vein and its right branch, occurring in the setting of early-stage cirrhosis after a preceding episode of cholecystitis.

A Case of Disappearing Ascites: Late Presentation of Acute Portal Vein Thrombosis After a Motor Vehicle Accident

Portal vein thrombosis (PVT) has been usually diagnosed as a complication secondary to cardiac, hepatic, and malignant etiologies, but it has rarely been described in the setting of blunt abdominal trauma. This case depicts an older male who presented to the emergency department with progressive ascites and lower extremity edema within two weeks after a motor vehicle accident (MVA). Ascitic fluid analysis indicated the presence of portal hypertension, which prompted extensive evaluation to determine the etiology. Further workup, including hypercoagulable and malignancy screening, unveiled the diagnosis of acute PVT secondary to abdominal blunt force trauma, showing a rather rare presentation.

Anticoagulation therapy for portal vein thrombosis in patients with liver cirrhosis

BACKGROUND

Portal vein thrombosis (PVT) is a frequent complication of cirrhosis, which is significantly associated with progressive hepatic decompensation such as ascites and a high mortality risk. Anticoagulation may associate with higher PVT regression rates, but the safety of anticoagulation should be considered.

AIM

To investigate the efficacy and safety of anticoagulation therapy for PVT in patients with liver cirrhosis.

METHODS

We conducted a retrospective study of cirrhotic patients diagnosed with PVT from January 2018 to December 2021, comparing those who received anticoagulation therapy to those who did not. Thirty-two patients received low molecular weight heparin (LMWH), warfarin, or rivaroxaban (anticoagulation group), and 52 were untreated (non-anticoagulation group). All patients were followed to assess the evolution of PVT (thrombus regression, stable, and progression) and the adverse effects of anticoagulation therapy.

RESULTS

A total of 84 patients were followed for a median 13 mo (IQR: 6-24 mo). Thirty-two patients (38.1%) received anticoagulation therapy. Anticoagulation therapy was associated with a higher PVT regression rate (50.0% vs 23.1%, P = 0.010) (univariable hazard ratio [HR] for regression of PVT with anticoagulation = 0.300, 95% confidence interval [CI]: 0.116-0.773, P = 0.013; multivariable HR for regression of PVT with anticoagulation = 0.185, 95%CI: 0.061-0.560, P = 0.003). Anticoagulation therapy was stopped in six patients because of adverse effects, of which two were due to abdominal pain, two due to gastrointestinal bleeding, and two due to hematuria. Symptoms improved after drug withdrawal.

CONCLUSION

Our findings support anticoagulation therapy in cirrhotic patients with non-malignant PVT, since anticoagulation seems safe and associated with superior PVT regression rates.

Direct portal vein recanalization with stenting associated with embolization of esophagogastric varices in a patient with portal vein thrombosis

Introduction

Chronic extrahepatic non-tumoral thrombotic portal vein occlusion in non-cirrhotic patients is a rare condition, affecting 5–10% of patients with portal hypertension.

Presentation of case

The present study reports the case of a young patient without previous comorbidities who presented with portal hypertension secondary to chronic extrahepatic non-tumoral thrombotic occlusion of the portal vein. He underwent portal recanalization with a 12 × 80 mm nitinol self-expandable stent and embolization of esophagogastric varices with fibrous springs and cyanoacrylate via transparieto-hepatic access. Immediate resolution of the trans-lesion pressure gradient was obtained transoperatively, while complete remission of esophagogastric varices was verified by endoscopic control during outpatient follow-up.

Discussion

Chronic portal vein occlusion is associated or not with liver cirrhosis. The chronic phase is characterized by cavernomatous transformation of the portal vein, which consists of the formation of multiple collaterals that bypass the lesion. This phase usually courses with portal hypertension and consequent variceal gastrointestinal bleeding. Decompression of the portal system through direct recanalization (angioplasty with stenting) is one therapeutic options.

Conclusion

We conclude that, in the present case, resolving portal hypertension by direct portal recanalization was a good therapeutic option, as it decompressed the portal system while maintaining the hepatopetal flow.

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Chronic extrahepatic non-tumoral thrombotic portal occlusion is a rare condition.

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Portal recanalization with stent for resolution of portal hypertension.

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Transparieto-hepatic access is the approach of choice among non-cirrhotics.

Delayed-Onset Portal Venous Thrombosis After Ingestion of 3% Hydrogen Peroxide

BACKGROUND

Identification of portal venous gas on radiographic imaging is well documented after the ingestion of hydrogen peroxide, as is its resolution after hyperbaric therapy. Although hyperbaric therapy may resolve the gastrointestinal symptoms associated with the presence of portal venous gas, the principle rationale for performing hyperbaric therapy is to prevent subsequent central nervous system oxygen embolization.

CASE REPORT

We describe a patient with portal venous gas identified by computed tomography after the ingestion of 3% hydrogen peroxide, managed without hyperbaric therapy, who subsequently developed portal venous thrombosis. We are not aware of this complication being previously described from hydrogen peroxide ingestion. The case is complicated by the coexistence of a self-inflicted stab wound, leading to exploratory laparotomy in a patient predisposed to arterial vascular occlusion. Why Should an EmergencyPhysicianBeAware of This? Emergency physicians will encounter patients after the ingestion of hydrogen peroxide who, despite not having symptoms of central nervous system emboli, have portal venous gas identified on radiographic imaging. Being aware that the principle rationale for prophylactic utilization of hyperbaric therapy is to prevent subsequent central nervous system emboli, and that in at least one case, delayed-onset portal venous thrombosis has occurred without hyperbaric therapy may help contribute to clinical decision-making.

Nomogram Model for Prediction of Portal Vein Thrombosis in Patients with Liver Cirrhosis After Splenectomy: A Retrospective Analysis of 2 Independent Cohorts

Background

The aim of this study was to establish and validate an easy-to-use nomogram to predict portal vein thrombosis (PVT) in patients with cirrhosis after splenectomy and to test its predictive ability.

Material/Methods

This retrospective study included 315 patients with cirrhosis who underwent splenectomy at 2 high-volume medical centers. The least absolute shrinkage and selection operator (LASSO) regression method was used to select the predictors in the training cohort, and multivariable logistic regression analysis was performed to establish the predictive nomogram model. We determined the prediction value of the nomogram by the area under the receiver operating characteristic curve (AUROC), the calibration curve, and decision curve analysis. Finally, the applicability of the nomogram was internally and independently validated.

Results

The predictors of PVT included portal vein diameter, splenic vein diameter, body mass index, and platelet count. Based on the clinical and radiomic models, the nomogram had good predictive efficiency for predicting PVT in patients with cirrhosis after splenectomy, with an AUROC of 0.887 (0.856 in internal validation and 0.796 in independent validation). The decision curve analysis revealed that the nomogram had good clinical application value.

Conclusions

We successfully developed an easy-to-use nomogram to predict the probability of PVT in patients with cirrhosis after splenectomy. The nomogram can help clinicians make timely, individualized clinical decisions for PVT in patients with cirrhosis after splenectomy.

Portal Vein Thrombosis after the Consumption of Date Seed Powder: A Case Study

Date seeds can be used as ingredients to enhance the nutritional value of some functional foods for human consumption as well as additives in pharmaceutical and cosmetic industries. However, there are no reports on the complications of date seeds after oral consumption. We currently report a patient with no history of gastrointestinal disease, who has been admitted to the hospital with portal vein thrombosis (PVT) and suffered from complications.

Predictors of insufficient recanalization and portal hypertensive complications after treatment of non-cirrhotic, non-malignant portal vein thrombosis - a population-based study

OBJECTIVES

In acute portal vein thrombosis (PVT), a six-month anticoagulation treatment achieves complete recanalization in only 35%-45% of patients, but the predictors of poor treatment responses are unclear. We examined treatment outcomes in PVT and aimed to identify predictors of incomplete recanalization and portal hypertensive complications.

MATERIALS AND METHODS

This retrospective study comprised patients diagnosed with PVT between 2006 and 2015. Key exclusion criteria were liver cirrhosis, malignancy, and age <18.

RESULTS

The final cohort comprised 145 patients, of whom 132 (92%) were primarily treated with anticoagulation. The 5-year cumulative incidence of complete recanalization was 42% and of portal hypertensive complications, 31%. Independent predictors of insufficient recanalization were sub-acute or chronic thrombosis (hazard ratio (HR) 3.1, 95% CI 1.6-5.8), while acute pancreatitis was a protective factor (HR 0.3, 95% CI 0.2 - 0.7). Independent predictors of incident portal hypertensive complications were as cites at baseline (HR 3.3, 95% CI 1.7-6.7), sub-acute or chronic thrombosis (HR 2.9, 95% CI 1.6-5.3), extension of thrombosis to the splenic or mesenteric vein (HR 2.6, 95% CI 1.2-5.7), myeloproliferative disease (HR 3.0, 95% CI 1.4-6.5), and anemia (HR 2.1, 95% 1.1-3.9), while acute pancreatitis was a protective factor (HR 0.1, 95% CI 0.03-0.5).

CONCLUSIONS

Etiology and age of thrombosis are associated with treatment responses in PVT. The presence of ascites at baseline, etiology, and extent of thrombosis, a non-acute thrombosis and anemia, are associated with the risk of portal hypertensive complications. Etiology and extent of thrombosis should be taken into account when determining the treatment (method) for PVT.

Pylephlebitis treated with apixaban

Pylephlebitis is a rare condition that is characterized by an infected thrombus of the portal vein system and was traditionally associated with a high mortality rate prior to the introduction of antibiotics. This report details a 77-year-old Chinese male found to have a splenic vein thrombosis, Parvimonas micra bacteremia, and a polymicrobial splenic abscess. The patient was treated with abscess drainage and a 6 week course of intravenous antibiotics, and a direct oral anticoagulant, apixaban 2.5 mg twice daily. To our knowledge, this is the second documented case of pylephlebitis treated with apixaban. Here, we summarize our experience treating this case of pylephlebitis and briefly report on the existing body of literature.

Acute portal vein thrombosis after liver transplant presenting with subtle ultrasound abnormalities: A case report and literature review

BACKGROUND

Portal vein thrombosis (PVT) after liver transplantation (LT) is an uncommon complication with potential for significant morbidity and mortality that transplant providers should be cognizant of. Recognizing subtle changes in post-operative ultrasounds that could herald but do not definitively diagnose PVT is paramount.

CASE SUMMARY

A 30-year-old female with a history of alcohol-related cirrhosis presented with painless jaundice and received a deceased donor orthotopic liver transplant. On the first two days post-operatively, her liver Doppler ultrasounds showed a patent portal vein, increased hepatic arterial diastolic flows, and reduced hepatic arterial resistive indices. She was asymptomatic with improving labs. On post-operative day three, her resistive indices declined further, and computed tomography of the abdomen revealed a large extra-hepatic PVT. The patient then underwent emergent percutaneous venography with tissue plasminogen activator administration, angioplasty, and stent placement. Aspirin was started to prevent stent thrombosis. Follow-up ultrasounds showed a patent portal vein and improved hepatic arterial resistive indices. Her graft function improved to normal by discharge. Although decreased hepatic artery resistive indices and increased diastolic flows on ultrasound are often associated with hepatic arterial stenosis post-LT, PVT can also cause these findings.

CONCLUSION

Reduced hepatic arterial resistive indices on ultrasound can signify PVT post-LT, and thrombolysis, angioplasty, and stent placement are efficacious treatments.

Intrahepatic portal vein thrombosis due to postoperative biliary obstruction successfully treated by a partial thrombectomy combined with thrombolytic drug therapy

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Portal vein thrombosis due to constriction of hepaticojejunostomy is rarely occured, in which increased biliary pressure by obstructive jaundice decreased portal flow.

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Re-anastomosis and postoperative thromolytic therapy recovered occluded portal flow.

Introduction

This case report aims to inform pancreatic surgeons about our perioperative management of intrahepatic portal vein thrombosis caused by an obstruction of hepaticojejunostomy (HJ) after pancreaticoduodenectomy (PD).

Case presentation

A 65-year-old woman was diagnosed with pancreas head carcinoma involving the superior mesenteric vein (SMV). Pancreaticoduodenectomy combined with SMV resection was followed by HJ. Twisting or narrowing was not evident during anastomosis. Total bilirubin values progressively increased to 13 mg/dL on day 5. At that time, we suspected anastomotic occlusion and found complete portal thrombosis of the left liver. Therefore, emergency re-anastomosis of the HJ was followed by thrombectomy, which was not completely successful and did not completely recover initial portal flow. Thrombolytic drugs improved obstructive jaundice, eradicated the organized thrombosis and recovered the portal flow by day 30. The post-operative course was uneventful.

Discussion

A thrombosis immediately formed in the portal vein due to biliary obstruction of an anastomotic site. We speculated that biliary dilation and related inflammation caused a relative increase in arterial flow and decreased portal flow at the localized part of the umbilical portion. Although early surgical thrombectomy was attempted soon after the primary operation, the organized thrombosis persisted. However, thrombolytic therapy eradicated the thrombosis.

Conclusion

Careful anastomosis of HJ during PD was necessary to avoid postoperative biliary stricture. This type of complication affects intrahepatic blood flow, particularly via the portal vein. Although immediate re-anastomosis or thrombectomy is applied, organized thrombosis cannot always be surgically removed.

Portal Vein Thrombosis in Cirrhosis

Portal vein thrombosis (PVT) in the cirrhotic population is a challenging clinical phenomenon requiring a nuanced management approach. Uncertainty exists regarding the clinical significance of PVT in the cirrhotic population because the data for PVT are based mainly on retrospective, small cohort studies. Therefore, strong recommendations regarding the optimal timing, modality, and duration of therapy for PVT in the cirrhotic population cannot be made. However, this review aims to summarize the current literature and provide stepwise guidance in diagnosing and managing PVT in patients with cirrhosis.

A systematic review of portomesenteric vein thrombosis after sleeve gastrectomy

BACKGROUND

Portomesenteric vein thrombosis (PMVT) is considered an uncommon complication in general surgery; nevertheless, with the growing popularity of sleeve gastrectomy (SG) as a bariatric procedure we have seen an increase in the occurrence of this complication.

OBJECTIVES

To elucidate the question if it is a procedure-related complication and explore the modalities of prevention and treatment of this complication, a systematic review of available literature regarding PMVT events after SG was conducted.

METHODS

Our systematic review yielded 28 studies enclosing 89 patients. Perioperative data was collected from each study and analyzed.

RESULTS

The incidence of PMVT after SG ranged from .37% to 1%, 65% of the patients were female, and the mean body mass index was 41.63 kg/m². Perioperative co-morbidities including hypertension, diabetes, and dyslipidemia were recorded in 39.7%, 41.63%, and 38.23% of cases respectively. Tachycardia and fever were reported only in 23.9% and 20.89%, respectively, and hereditary thrombophilia studies were positive in 30.43% of cases. The rate of acute major complications after PMVT was 14.6% (13 cases), and mortality was reported in 3 cases (average 3.37%).

CONCLUSION

PMVT seems to be an uncommon multifactorial disease, with unpredictable symptoms and varieties of the treatments options, but additional studies are required to further define optimal management and prevention algorithms.

Portomesenteric vein thrombosis after laparoscopic sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass: a 36-case series

BACKGROUND

Portomesenteric vein thrombosis following laparoscopic bariatric surgical procedures is a serious and potentially lethal complication. It is quite rare, and its clinical presentation, management, and sequelae remain poorly understood.

METHODS

We searched PubMed, Medline, Google Scholar, Ovid, and Cochrane databases for articles reporting case series and systematic reviews in the English language on patients who underwent laparoscopic bariatric surgery and had a subsequent portal or mesenteric vein thrombosis. Articles discussing laparoscopic gastric banding were excluded.

RESULTS

A total of 14 articles reporting on 36 cases were found. We analyzed the pooled data from these case reports and series with emphasis on number of reported patients, demographics, time of diagnosis, risk factors, symptoms, management, complications, and sequelae.

CONCLUSIONS

Portomesenteric vein thrombosis is not uncommon following laparoscopic bariatric surgery and appears to occur more after laparoscopic sleeve gastrectomy. Bariatric surgeons should have a high index of suspicion for early detection and treatment of this potentially lethal complication. Obese patients at high risk for venous thrombosis should be screened for genetic predisposition for hypercoagulable state and should be considered for extended thromboprophylaxis postoperatively.

Clinical Management of Acute Portal/Mesenteric Vein Thrombosis

Background

Acute thrombosis of the portal vein (PV) and/or the mesenteric vein (MV) is a rare but potentially life-threatening disease. A multitude of risk factors for acute portal vein thrombosis (PVT)/mesenteric vein thrombosis (MVT) have been identified, including liver cirrhosis, malignancy, coagulation disorders, intra-abdominal infection/inflammation, and postoperative condition.

Methods

This article analyses the treatment options for acute PVT/MVT.

Results

Initially, the clinical management should identify patients with an intra-abdominal focus requiring immediate surgical intervention (e.g. bowel ischaemia). Subsequently, emphasis is placed on the recanalization of the PV/MV or at least the prevention of thrombus extension to avoid long-term complications of portal hypertension. Several therapeutic options are currently available, including anticoagulation therapy, local/systemic thrombolysis, interventional or surgical thrombectomy, and a combination of these procedures. Due to the lack of prospective randomized studies, a comparison between these therapeutic approaches regarding the efficacy of PV/MV recanalization is difficult, if not impossible.

Conclusion

In patients with acute PVT/MVT, an individualized treatment based on the clinical presentation, the underlying disease, the extent of the thrombosis, and the patients' comorbidities is mandatory. Therefore, these patients should be considered for an interdisciplinary therapy in specialized centres with the option to utilise all therapeutic approaches currently available.

Portal vein thrombosis as a rare cause of abdominal pain: When to consider?

Extrahepatic portal vein thrombosis (PVT) is a rare condition that is characterized by the presence of thrombus within any segment of the portal vein, including the right and left intrahepatic branches. It may also extend to the splenic or superior mesenteric veins. Portal vein thrombosis may be related to cirrhosis or liver malignancy as well as to local inflammatory conditions in the abdomen and genetic or acquired thrombophilic diseases. Currently, PVT is being increasingly diagnosed due to advances in modern imaging techniques. The clinical presentation has a wide range, from an asymptomatic lesion to a potentially life-threatening situation. In this study, we present three patients with PVT. The diagnosis was made by radiologic and clinical findings. In the first patient, genetic testing revealed factor V Leiden mutation as the cause of PVT. The second patient was diagnosed with lupus anticoagulant syndrome as the cause of PVT. Portal vein thrombosis was associated with intra abdominal infection due to anastomotic leakage in the third patient. Two patients were successfully treated with anticoagulant therapy. This report emphasizes that even though PVT is a rare cause of abdominal pain, timely diagnosis and appropriate management is vital due to its lethal complications such as mesenteric ischemia and mesenteric infarct.

Effects of surgical procedures on the occurrence and development of postoperative portal vein thrombosis in patients with cirrhosis complicated by portal hypertension

OBJECTIVE

We have compared the influences of three surgical strategies on the occurrence and development of portal vein thrombosis (PVT) in patients with liver cirrhosis complicated by portal hypertension (PHT) in this study.

METHODS

Total 116 patients who respectively underwent pericardial devascularization (PCDV) with splenectomy (PDS group: n = 50), selective PCDV (SPD group: n = 28) and splenorenal shunt (SRS) combined with PCDV (combined group: n = 38) were investigated in this study. The incidence of PVT before and after operation was monitored. The incidence of Grade II-IV PVT was used to assess the severity of PVT. The liver function was assessed according to the Child-Pugh classification.

RESULTS

The incidence and severity of PVT and live function were similar among the three groups before operation (P > 0.05). The incidence of PVT was significantly increased after surgery in each group (P < 0.001), but recovered to the baseline level at six months in combined group (P = 0.629). Besides, the severity of PVT was significantly aggravated in PDS (P < 0.001) and SPD (P = 0.026) groups after operation, but not in combined group (P = 0.525). Patients in combined group showed significantly lower incidence and severity of PVT than those in the other two groups at each follow-up time point (P < 0.05). In addition, the liver function in the combined group was significantly improved compared with the other two groups.

CONCLUSIONS

SRS combined with PCDV is superior to PCDV with splenectomy and selective PCDV for PHT in liver cirrhotic patients in inhibiting the occurrence and development of postoperative PVT and improving liver function.

Portal vein thrombosis

Portal vein thrombosis (PVT) is a rare event in the general medical setting that commonly complicates cirrhosis with portal hypertension, and can also occur with liver tumors. The diagnosis is often incidental when a thrombus is found in the portal vein on imaging tests. However, PVT may also present with clinical symptoms and can progress to life-threatening complications of ischemic hepatitis, liver failure, and/or small intestinal infarction. This article reviews the pathophysiology of this disorder, with a major focus on PVT in patients with cirrhosis, and presents detailed guidelines on optimal diagnostic and therapeutic strategies.

Predictors of thrombosis in hepatic vasculature during microwave tumor ablation of an in vivo porcine model

PURPOSE

To evaluate and model the risk of in vivo thrombosis in each hepatic vessel type during hepatic microwave ablation as a function of vessel diameter, velocity, and vessel-antenna spacing.

MATERIALS AND METHODS

A single microwave ablation antenna was inserted into a single porcine lobe (n = 15 total) adjacent to a hepatic artery, hepatic vein, or portal vein branch. Conventional ultrasound and Doppler ultrasound were used to measure the vessel diameter, blood flow velocity, and vessel-antenna spacing. A microwave ablation zone was created at 100 W for 5 minutes. Thrombus formation was evaluated on ultrasound performed immediately after the procedure. Logistic regression was used to evaluate the predictive value of vessel diameter, blood flow velocity, and vessel-antenna spacing on vascular thrombosis.

RESULTS

Thrombosis was identified in 53% of portal veins, 13% of hepatic veins, and 0% of hepatic arteries. The average peak blood flow rate of the hepatic artery was significantly greater than the average peak blood flow rate of the hepatic vein and portal vein. Peak blood flow velocity < 12.45 cm/s, vessel diameter < 5.10 mm, and vessel-antenna spacing < 3.75 mm were strong predictors of hepatic vein thrombosis. However, these individual factors were not predictive of the more common portal vein thrombosis.

CONCLUSIONS

Hepatic arteries do not appear to be at risk for thrombosis during microwave ablation procedures. Portal vein thrombosis was more common than hepatic vein thrombosis during microwave ablation treatments but was not as predictable based on vessel diameter, flow velocity, or vessel-antenna spacing alone.