Hemodynamic changes in the hepatic circulation after the modulation of the splenic circulation in an in vivo human experimental model

Graft inflow modulation in recipients with portal hypertension

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching, potentially leading to the "small-for-size syndrome" (SFSS). SFSS is a rare dysfunction that may affect a partial liver graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. A key role in the physiopathology of SFSS is played by portal hypertension (PHT) to which a small allograft is submitted after reperfusion, resulting in sinusoidal congestion and hemorrhage. Portal overflow injures the liver directly through nutrient excess, endothelial activation, and sinusoidal shear stress, and indirectly through arterial vasoconstriction. Thus, SFSS prevention relies not only on increasing graft volume (implementing the use of larger grafts or auxiliary/dual liver transplantation), but also on the control of the increased portal vein pressure (PVP) and portal vein flow (PVF). To this aim, surgical graft inflow modulation techniques (GIM) such as splenic artery ligation (SAL), splenectomy and hemiportocaval shunts, can be considered when an imbalance between the PVP and the hepatic arterial flow (HAF) is acknowledged. However, such strategies have their pros and cons, and a deep knowledge of the indications and complications is needed. Furthermore, pharmacological modulation has also been proposed. This review is aimed to update available literature on the current knowledge and strategies for modulating portal vein flow in LDLT.

Small-For-Size Syndrome and Graft Inflow Modulation Techniques in Liver Transplantation

BACKGROUND

Partial liver transplantation has recently been proposed to alleviate organ shortages. However, transplantation of a small-for-size graft is associated with an increased risk of posttransplant hepatic dysfunction, commonly referred to as small-for-size syndrome (SFSS). This review describes the etiology, pathological features, clinical manifestations, and diagnostic criteria of SFSS. Moreover, we summarize strategies to improve graft function, focusing on graft inflow modulation techniques. Finally, unmet needs and future perspectives are discussed.

SUMMARY

In fact, posttransplant SFSS can be attributed to various factors such as preoperative status of the recipients, surgical techniques, donor age, and graft quality, except for graft size. With targeted improvement measures, satisfactory clinical outcomes can be achieved in recipients at increased risk of SFSS. Given the critical role of relative portal hyperperfusion in the pathogenesis of SFSS, various pharmacological and surgical treatments have been established to reduce or partially divert excessive portal inflow, and recipients will benefit from individualized therapeutic regimens after careful evaluation of benefits against potential risks. However, there remain unmet needs for further research into different aspects of SFSS to better understand the correlation between portal hemodynamics and patient outcomes.

KEY MESSAGES

Contemporary transplant surgeons should consider various donor and recipient factors and develop case-specific prevention and treatment strategies to improve graft and recipient survival rates.

Small-diameter TIPS combined with splenic artery embolization in the management of refractory ascites in cirrhotic patients

PURPOSE

Maximally decreasing portal pressures with transjugular intrahepatic portosystemic shunt (TIPS) is associated with improved ascites control but also increased encephalopathy incidence. Since splenic venous flow contributes to portal hypertension, we assessed if combining small-diameter TIPS with splenic artery embolization could improve ascites while minimizing encephalopathy.

METHODS

Fifty-five patients underwent TIPS creation for refractory ascites. Subjects underwent creation of 8 mm TIPS followed by proximal splenic artery embolization (group A, n=8), or of 8 mm (group B, n=6) or 10 mm TIPS (group C, n=41) without splenic embolization. Data were retrospectively reviewed.

RESULTS

In group A, median portosystemic gradient decreased from 19 mmHg to 9 mmHg after TIPS, and 8 mmHg after subsequent splenic artery embolization. In groups B and C, gradient decreased from 15 mmHg to 8 mmHg and 16 mmHg to 6 mmHg. All patients except for one in group A and two in C had greater than 50% reduction in the number of paracenteses in 3 months. Any postprocedural encephalopathy incidence was 62%, 50%, 83% in groups A, B, and C, respectively. Overall, 20% of subjects with 10 mm TIPS required TIPS reduction/closure compared to 7% of subjects with 8 mm TIPS.

CONCLUSION

We found that 8 mm diameter TIPS provided similar ascites control compared to 10 mm TIPS regardless of splenic embolization. While more patients with 10 mm TIPS required reduction/closure for severe encephalopathy, the study was underpowered for definitive assessment. Splenic embolization might have the potential to further decrease portosystemic gradient and ascites as an alternative to dilation of TIPS to 10 mm minimizing the risk of encephalopathy, but larger studies are warranted.

Treatment on the Spleen Prevents the Progression of Secondary Sarcopenia in Patients With Liver Cirrhosis

Hyperammonemia is an important stimulator of myostatin expression, a negative regulator of muscle growth. After splenectomy or partial splenic artery embolization (PSE), hyperammonemia often improves. Thus, we investigated changes in skeletal muscle index (SMI) in patients following an operation on the spleen and in patients who did not undergo an operation on their spleen. The study was designed retrospectively, in which we analyzed data collected between January 2000 and December 2015. Patients were assigned to the splenectomy/PSE or nontreatment group. Changes in SMI (ΔSMI), ammonia (Δammonia), myostatin (Δmyostatin), irisin (Δirisin), and branched‐chain amino acids/tyrosine molar ratio (ΔBTR) were analyzed between baseline and 5‐year follow‐up both before and after inverse probability of treatment weighting adjustment (IPTW). Patients (102) were enrolled (splenectomy/PSE, n = 45; nontreatment group, n = 57) before IPTW adjustment: ΔSMI (2.6 cm²/m² vs. −8.8 cm²/m², respectively) (P < 0.001), Δmyostatin (−867 vs. −568, respectively) (P < 0.001), Δammonia (−34 and 16, respectively) (P < 0.001), and ΔBTR (0.89 and −0.665, respectively) (P < 0.001). There were no differences between splenectomy and PSE regarding these factors. Moreover, after IPTW adjustment, significant differences were observed between the splenectomy/PSE and nontreatment group for the median ΔBTR (0.89 and −0.64, respectively) (P < 0.001), Δammonia (−33 and 16, respectively) (P < 0.001), Δmyostatin (−894 and 504, respectively) (P < 0.001), and ΔSMI (1.8 cm²/m² and −8.2 cm²/m², respectively) (P < 0.001). Conclusions: Both splenectomy and PSE were associated with the prevention of secondary sarcopenia in patients with LC. Moreover, it can be expected that muscle volume loss is reduced by splenectomy or PSE in patients with hyperammonemia.

Small-for-size graft, small-for-size syndrome and inflow modulation in living donor liver transplantation

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching called "small-for-size syndrome (SFSS)." The initial trials to resolve this problem involved increasing the procured graft size, from left to right, and even extending to include a right lobe graft. Clinical cases of living right lobe donations have been reported since then, drawing attention to the risks of increasing the liver volume procured from a living donor. However, not only other modes of increasing graft volume (GV) such as auxiliary or dual liver transplantation, but also control of the increased portal pressure caused by a small-for-size graft (SFSG), such as a porto-systemic shunt or splenectomy and optimal outflow reconstruction, have been trialed with some positive results. To establish an effective strategy for transplanting SFSG and preventing SFSS, it is essential to have precise knowledge and tactics to evaluate graft quality and GV, when performing these LDLTs with portal pressure control and good venous outflow. Thus, we reviewed the updated literature on the pathogenesis of and strategies for using SFSG.

Post-operative assessment in patients after liver transplantation: imaging parameters associated with 1-year graft failure

PURPOSE

To identify post-liver transplant CT findings which predict graft failure within 1 year.

MATERIALS AND METHODS

We evaluated the CT scans of 202 adult liver transplants performed in our institution who underwent CT within 3 months after transplantation. We recorded CT findings of liver perfusion defect (LPD), parenchymal homogeneity, and the diameters and attenuations of the hepatic vessels. Findings were correlated to 1-year graft failure, and interobserver variability was assessed.

RESULTS

Forty-one (20.3%) of the 202 liver grafts failed within 1 year. Graft failure was highly associated with LPD (n = 18/25, or 67%, versus 15/98, or 15%, p < 0.001), parenchymal hypoattenuation (n = 20/41, or 48.8% versus 17/161, or 10.6%, p < 0.001), and smaller diameter of portal veins (right portal vein [RPV], 10.7 ± 2.7 mm versus 14.7 ± 2.2 mm, and left portal vein [LPV], 9.8 ± 3.0 mm versus 12.4 ± 2.2 mm, p < 0.001, respectively). Of these findings, LPD (hazard ratio [HR], 5.43, p < 0.001) and small portal vein diameters (HR, RPV, 3.33, p < 0.001, and LPV, 3.13, p < 0.05) independently predicted graft failure. All the measurements showed fair to moderate interobserver agreement (0.233~0.597).

CONCLUSION

For patients who have CT scan within the first 3 months of liver transplantation, findings of LPD and small portal vein diameters predict 1-year graft failure.

KEY POINTS

•Failed grafts are highly associated with liver perfusion defect, hypoattenuation, and small portal vein. •Right portal vein < 11.5 mm and left portal vein < 10.0 mm were associated with poor graft outcome. •Liver perfusion defect and small portal vein diameter independently predicted graft failure.

Liver Transplantation

The field of liver transplantation has changed since the MELD scoring system became the most widely used donor allocation tool. Due to the MELD-based allocation system, sicker patients with higher MELD scores are being transplanted. Persistent organ donor shortages remain a challenging issue, and as a result, the wait-list mortality is a persistent problem for most of the regions. This chapter focuses on deceased donor and live donor liver transplantation in patients with complications of portal hypertension. Special attention will also be placed on donor-recipient matching, perioperative management of transplant patients, and the impact of hepatic hemodynamics on transplantation.

Impact of imbalanced graft-to-spleen volume ratio on outcomes following living donor liver transplantation in an era when simultaneous splenectomy is not typically indicated

The impact of an imbalanced graft-to-spleen volume ratio (GSVR) on posttransplant outcomes other than postreperfusion portal hypertension remains unknown. The importance of GSVR might vary according to whether simultaneous splenectomy (SPX) is performed. This retrospective study divided 349 living donor liver transplantation (LDLT) recipients from 2006 to 2017 into 2 groups: low GSVR (≤0.70 g/mL) and normal GSVR (>0.70 g/mL). The cutoff value of GSVR was set based on the first quartile of the distributed data. Graft survival and associations with various clinical factors were investigated between the groups according to whether SPX was performed. Low GSVR did not affect outcomes when SPX was performed. In contrast, it was associated with an increased incidence of early graft loss (EGL) and poor graft survival by presenting posttransplant thrombocytopenia, cholestasis, coagulopathy, and massive ascites when the spleen was preserved. Among patients with a preserved spleen, the multivariable analysis results revealed that older donor age and low GSVR were independent risk factors for graft loss. In conclusion, low GSVR was an independent predictor of graft loss after LDLT when the spleen was preserved. Preserved spleen with extremely low GSVR may be related to persistent hypersplenism, impaired graft function, and consequent EGL.

Predictive Value of Hepatic Venous Pressure Gradient for Graft Hemodynamics in Living Donor Liver Transplantation

The hepatic venous pressure gradient (HVPG) measurement is known to correlate with the severity of portal hypertension in patients with liver cirrhosis. This retrospective study investigated the clinical value of preoperative measurement of HVPG in patients who underwent adult-to-adult living donor liver transplantation (LDLT) and its predictive value for hepatic hemodynamics after graft reperfusion. For this study, 75 patients who underwent adult-to-adult LDLT were divided into 2 groups (HVPG <16 mm Hg or HVPG ≥16 mm Hg) to investigate the correlation between preoperative HVPG and characteristics and surgical outcomes of the patients, including portal vein flow (PVF) and hepatic artery flow (HAF) after graft reperfusion. In total, 35 (46.7%) patients had an HVPG ≥16 mm Hg. These patients had significantly higher international normalized ratio values, serum creatinine levels, and Model for End-Stage Liver Disease scores compared with the 40 patients with HVPG <16 mm Hg. They also had higher rates of variceal bleeding, encephalopathy, and intractable ascites as well as lower serum albumin levels and platelet counts compared with those patients with HVPG <16 mm Hg. Portal inflow modulation (PIM) was frequently performed in the patients with HVPG ≥16 mm Hg compared with those with HVPG <16 mm Hg. No significant differences in surgical outcomes after LDLT were found between these 2 groups except for postoperative ascites. Preoperative HVPG showed a positive correlation with PVF and a negative correlation with HAF after graft reperfusion (false discovery rate [FDR] P = 0.08 and FDR P = 0.08, respectively). In linear regression analyses, preoperative HVPG was independently associated with PVF after graft reperfusion. In conclusion, our findings indicate that preoperative HVPG is associated with hepatic hemodynamics after graft implantation in LDLT. HVPG as a routine preoperative evaluation may be helpful for surgical planning of PIM.

Vascular Remodeling of Visceral Arteries Following Interruption of the Splenic Artery During Liver Transplantation

Splenic artery (SA) ligation can be performed during liver transplantation (LT) to avoid portal hyperperfusion, which is involved in the pathogenesis of both small-for-size and SA syndrome. The SA can also be used as an inflow for arterial reconstruction. Exceptionally, SA interruption or agenesis has been associated with positive remodeling of collateral arteries supplying the spleen via the left gastric artery (LGA), short gastric vessels, and the gastroepiploic arcade (GEA), with subsequent severe upper gastrointestinal (GI) bleeding. To determine incidence, magnitude, predictors, and clinical implications of vascular remodeling after SA interruption during LT, we identified 465 patients transplanted in the period 2007-2017 who had the SA ligated or interrupted at LT. Among them, 88 had a computed tomography angiography suitable for evaluation of vascular remodeling after LT. The presence of prominent gastric arterial collaterals and the increase in LGA and GEA diameter were evaluated on 2-dimensional axial images and multiplanar reconstructions. Of the 88 patients, 28 (31.8%), 32 (36.4%), and 22 (25.0%) developed gastric collateralization graded as mild, moderate, or severe. Of the patients for whom comparison with pre-LT imaging was possible (n = 54), 51 (94.4%) presented a median 37% and 55% increase in LGA and GEA diameter, respectively. Severe gastric collateralization was associated with lower body mass index (odds ratio, 0.84; 95% confidence interval [CI], 0.71-0.98; P = 0.03), whereas a GEA caliper measurement increase was positively correlated with Model for End-Stage Liver Disease score (r² = 0.12; 95% CI, 0.65-4.15; P = 0.008). Out of 465 patients, 2 (0.43%) had severe episodes of arterial upper GI bleeding, possibly exacerbated by vascular remodeling. In conclusion, vascular remodeling after SA interruption during LT is frequent and can aggravate GI bleeding during follow-up.

Application of Pediatric Donor Livers After Circulatory Death in Adult Liver Transplantation: A Single-Center Experience

OBJECTIVES

This study aimed to investigate the outcomes of adult liver transplant procedures using grafts from pediatric donors after circulatory death.

MATERIALS AND METHODS

We retrospectively analyzed the data of 19 pediatric-to-adult liver transplant procedures from July 2013 to May 2016 in our hospital. Nineteen adult liver transplant procedures were performed using livers from pediatric donors after circulatory death.

RESULTS

We performed 18 orthotopic and 1 piggyback liver transplant procedure. The median graft-to-recipient weight ratio was 1.26% (range, 0.86% to 2.46%). The median warm and cold ischemia times were 11 minutes (range, 8-20 min) and 638 minutes (range, 200-843 min), respectively. Complications after the operation included postoperative pulmonary infection (8 patients), fungal infection (1 patient), cytomegalovirus infection (1 patient), hepatic artery thrombosis and biliary stricture (1 patient), portal vein stenosis (1 patient), and graft failure (2 patients). For patients with graft failure, 1 patient received retransplant and 1 died. The patients were followed for 22.44 months (range, 9.63-44.07 mo) after transplant and showed normal liver function and good health. The 3-year survival rates of grafts and patients were 89.47% and 94.74%, respectively.

CONCLUSIONS

Appropriate evaluation of donors and recipients and accurate intraoperative and postoperative treatment can ensure successful application of livers from pediatric donors after circulatory death in adult recipients.

Proximal total splenic artery embolization for refractory hepatic encephalopathy

A Japanese woman with a history of Kasai operation for biliary atresia had living-donor liver transplantation at the age of 22. The first episode of refractory HE and late cellular rejection was treated by a high dose of methylprednisolone. The second episode of refractory HE was treated by balloon-occluded retrograde transvenous obliteration for a spleno-renal shunt. However, the third episode of refractory HE occurred 11 years after liver transplantation. The liver cirrhosis and hypersplenism were present with a Child-Pugh score of C-10. Although portal vein flow was hepatopetal, superior mesenteric vein flow regurgitated. We performed proximal total splenic artery embolization (TSAE). Superior mesenteric vein flow changed to a hepatopetal direction and she became clear. At a year after proximal TSAE, her spleen volume had decreased to 589 mL (20% decrease) on computed tomography. She is well and has a Child-Pugh score of 8 without overt HE. We report the first case of refractory HE treated by proximal TSAE that is a possible less invasive treatment option for a selected patient.

Outcomes of Liver Transplantation Using Pediatric Deceased Donor Livers: A Single-Center Analysis of 102 Donors

BACKGROUND

The outcome of pediatric deceased donor liver transplantation (LT) has not been well studied, especially pediatric deceased donor livers used in adult transplantation. This study aimed to evaluate the efficacy of LT using pediatric deceased donor livers and compare the outcomes between pediatric-to-pediatric LT and pediatric-to-adult LT.

METHODS

A retrospective review of LT using pediatric deceased donor livers from June 2013 to August 2016 was performed. The patients were divided into the pediatric-to-pediatric LT group and pediatric-to-adult LT group based on the ages of the recipients. The survival and incidence of early vascular complications (VCs) were observed between the two groups. We also analyzed the risk factors of early VCs in pediatric LT and the effect of donor hypernatremia on the prognosis of recipients.

RESULTS

There were 102 cases of LT using pediatric deceased donor livers in our hospital from June 2013 to August 2016, 83 pediatric-to-pediatric LT (recipients' age ≤13 years) and 19 pediatric-to-adult LT (recipients' age ≥19 years). The ratio of early VC was similar in the two groups (19.3% vs. 10.6%, P = 0.514). Low body weight of recipient was an independent risk factor of early VC in pediatric LT (odds ratio: 0.856, 95% confidence interval: 0.752-0.975, P = 0.019). The 1-year cumulative survival rates of grafts and patients were 89.16% and 91.57% in pediatric-to-pediatric LT and 89.47% and 94.74% in pediatric-to-adult LT, respectively (all P > 0.05). In all cases, patients using donors with hypernatremia (serum sodium levels ≥150 mmol/L) had worse graft survival (χ2=4.330, P = 0.037).

CONCLUSIONS

Pediatric-to-pediatric LT group has similar graft and patient survival rates with those of pediatric-to-adult LT group. Low body weight of recipients is an independent risk factor of early VC in pediatric LT. Patients using donors with hypernatremia have worse graft survival.

JOURNAL CLUB: Four-Dimensional Flow MRI-Based Splenic Flow Index for Predicting Cirrhosis-Associated Hypersplenism

OBJECTIVE

The objective of this study is to evaluate the ability of spleen volume, blood flow, and an index incorporating multiple measures to predict cirrhosis-associated hypersplenism.

MATERIALS AND METHODS

A total of 39 patients (14 women and 25 men; mean [± SD] age, 52 ± 10 years) with cirrhosis and sequelae of portal hypertension underwent 4D flow MRI and anatomic 3-T MRI performed before and after contrast administration. Unenhanced 4D flow MRI was used to assess abdominal hemodynamics, and splenic volumes were measured on T1-weighted gradient-recalled echo MRI. Relationships among demographic characteristics, blood component counts, splenic volume, arterial flow, venous flow, and the percentage of shunted portal flow were assessed in 29 consecutive patients (i.e., the derivation group), to develop a splenic flow index. This index was assessed along with splenic volume and blood flow alone in 10 additional consecutive patients (i.e., the validation group) via ROC curve analysis, to identify platelet counts of less than 50 × 10³ cells/μL, leukocyte counts of less than 3.0 × 10³ cells/μL, or both.

RESULTS

In the derivation cohort (platelet count, 129 ± 76 × 10³ cells/μL), splenic volume, arterial flow, venous flow, and the percentage of shunted portal flow were inversely correlated with platelet counts (ρ = -0.68, -0.68, -0.56, and -0.36, respectively; p < 0.05). Adding splenic volume to arterial flow and the product of venous flow and the percentage of shunted portal flow indexed to the body surface area yielded superior correlations with platelet counts, leukocyte counts, and the degree of severity of hypersplenism (ρ = -0.75, -0.48, and -0.75, respectively; p ≤ 0.001) and predicted severe hypersplenism (sensitivity, 100%; specificity, 100%) in the validation cohort (platelet count, 93 ± 71 × 10³ cells/μL).

CONCLUSION

A splenic flow index that incorporates both splenic volume and blood flow is a better indicator of hypersplenism than is splenic volume alone.

Splenectomy is not indicated in living donor liver transplantation

Simultaneous splenectomy (SPX) is preferentially performed in living donor liver transplantation (LDLT) to modulate portal flow; increase postoperative platelet count, especially among those with hepatitis C virus (HCV) infection; and modulate the immunologic status in ABO-incompatible cases. The negative effects of the procedure, however, are not well established. Records of 395 LDLTs performed at our institution, including 169 (42.8%) patients with simultaneous SPX and 226 (57.2%) patients with spleen preservation, were reviewed with special reference to the simultaneous SPX cases. The most common indication for SPX was HCV-related disease (n = 114), followed by low preoperative platelet count (n = 52), and other reasons (n = 3). Simultaneous splenectomy did not increase the platelet count in the early postoperative period, but the incidence of reoperation for postoperative hemorrhage was increased, mainly at the SPX site, within the first week. In addition, the operative time, intraoperative blood loss, and incidence of lethal infectious disease were significantly higher in the SPX group, whereas the incidence of small-for-size syndrome was comparable between groups. Finally, SPX was an independent predictor for both postoperative hemorrhage (odds ratio [OR] = 2.451; 95% confidence interval [CI] = 1.285-4.815; P = 0.006) and lethal infectious complication (OR = 3.748; 95% CI = 1.148-14.001; P = 0.03). In conclusion, on the basis of the present findings, we do not recommend simultaneous SPX in LDLT. Liver Transplantation 22 1526-1535 2016 AASLD.

Critical Illness in Patients With Asplenia

The critically ill, asplenic patient presents a variety of management challenges. Historically, the focus of the care of the asplenic population has been the prevention and management of infection, including the often-fatal overwhelming postsplenectomy infection with encapsulated organisms such as Streptococcus pneumoniae. Recently, however, there has been increasing recognition of the spleen's function in areas outside of immunity because the asplenic state has been identified as a risk factor for such vascular complications as thrombosis and pulmonary hypertension resulting from dysregulated inflammation and coagulation. Because of the relatively small size of this population and the relative infrequency with which critical illness occurs in it, there are few controlled trials that can serve as a basis for therapeutic maneuvers; thus, optimal management requires an astute clinician with an understanding of the pathogenetic mechanisms underlying the reported consequences of splenectomy. The purpose of this review is to explore the pathophysiology of the asplenic state-impairment in adaptive immunity, loss of blood filtration, endothelial dysfunction, and dysregulated coagulation-and how it leads to infection, thrombosis, and pulmonary hypertension as well as to discuss the implications of these conditions on the management of the critically ill, splenectomized patient.

Child-to-Adult Liver Transplantation With Donation After Cardiac Death Donors: Three Case Reports

Development of organ transplantation is restricted by the discrepancy between the lack of donors and increasing number of patients. The outcome of pediatric donors transplanted into adult recipients especially with donation after circulatory death (DCD) pattern has not been well studied. The aim of this paper is to describe our experience of 3 successful DCD donor child-to-adult liver transplantations lately. Three DCD donors were separately 7, 5, and 8 years old. The ratio between donor graft weight and recipient body weight was 1.42%, 1.00%, and 1.33%, respectively. Ratio between the volume of donor liver and the expected liver volume was 0.65, 0.46, and 0.60. Splenectomy was undertaken for the second recipient according to the portal vein pressure (PVP) which was observed during the operation. Two out of 3 of the recipients suffered with acute kidney injury and got recovered after renal replacement therapy. The first recipient also went through early allograft dysfunction and upper gastrointestinal bleeding. The hospital course of the third recipient was uneventful. After 1 year of follow-up visit, the first and second recipients maintain good quality of life and liver function. The third patient was followed up for 5 months until now and recovered well. DCD child-to-adult liver transplantation should only be used for comparatively matched donor and recipient. PVP should be monitored during the operation. The short-term efficacy is good, but long-term follow-up and clinical study with large sample evaluation are still needed.

Impact of contrast-enhanced ultrasound in the study of hepatic artery hypoperfusion shortly after liver transplantation: contribution to the diagnosis of artery steal syndrome

OBJECTIVE

To assess the value of contrast-enhanced ultrasound (CEUS) in the absence of hepatic artery signal on Doppler ultrasound (DUS) in the immediate postoperative period after liver transplant.

METHODS

This prospective study included 675 consecutive liver transplants. Patients without hepatic artery signal by DUS within 8 days post-transplant were studied with CEUS. If it remained undetectable, a thrombosis was suspected. In patent hepatic artery, a DUS was performed immediately after CEUS; if low resistance flow was detected, an arteriography was indicated. Patients with high resistance waveform underwent DUS+/CEUS follow-up. Arteriography was indicated when abnormal flow persisted for more than 5 days or liver dysfunction appeared.

RESULTS

Thirty-four patients were studied with CEUS. In 11 patients CEUS correctly diagnosed hepatic artery thrombosis. In two out of 23 non-occluded arteries, a low resistance flow lead to a diagnosis of stenosis/proximal thrombosis. Twenty-one patients had absence of diastolic flow, which normalized in the follow-up in 13 patients. In the remaining eight patients, splenic artery steal syndrome (ASS) was diagnosed.

CONCLUSIONS

CEUS allows us to avoid invasive tests in the diagnostic work-up shortly after liver transplant. It identifies the hepatic artery thrombosis and points to a diagnosis of ASS.

KEY POINTS

• CEUS is useful in the diagnostic work-up shortly after liver transplant • CEUS identifies the hepatic artery thrombosis with reliability • There is little information about DUS and CEUS findings in the ASS • DUS and CEUS offer functional information useful in the diagnosis of ASS.