Variability of clinical presentation of hepatic artery thrombosis in pediatric liver transplantation: role of imaging modalities

Evaluation and management of biliary complications after pediatric liver transplantation: pearls and pitfalls for percutaneous techniques

In pediatric liver transplantation, bile duct complications occur with a greater incidence than vascular anastomotic dysfunction and represent a major source of morbidity and mortality. While surgical re-anastomosis can reduce the need for retransplantation, interventional radiology offers minimally invasive and graft-saving therapies. The combination of small patient size and prevailing Roux-en-Y biliary enteric anastomotic techniques makes endoscopic retrograde cholangiopancreatography difficult if not impossible. Expertise in percutaneous management is therefore imperative. This article describes post-surgical anatomy, pathophysiology and noninvasive imaging of biliary complications. We review percutaneous techniques, focusing heavily on biliary access and interventions for reduced liver grafts. Subsequently we review the results and adverse events of these procedures and describe conditions that masquerade as biliary obstruction.

Postoperative Doppler Ultrasonography in Liver Transplantation

BACKGROUND

Doppler ultrasonography plays an important role in the postoperative management of liver transplantation. We present our initial experiences evaluating liver transplants with the use of postoperative Doppler sonography.

METHODS

In our hospital, we performed 20 liver transplantations from July 2014 to October 2016. Among 20 patients, we performed 15 deceased-donor liver transplantations (DDLTs) and 5 living-donor liver transplantations (LDLTs). For deceased donors, inferior vena cava anastomoses were performed with the use of the piggyback technique, and for living donors, modified right grafts were used with middle hepatic vein reconstruction by Dacron graft. In the intensive care unit, we performed Doppler ultrasound at least once a day and at every clinical need. We checked hepatic blood flow by means of Doppler ultrasound.

RESULTS

Eighteen patients underwent Doppler ultrasonography once a day up to postoperative day 6. Of the patients who received LDLT, 2 patients underwent Doppler ultrasonography twice a day because the operator was concerned about the hepatic artery anastomosis. Findings on Doppler ultrasound showed no abnormal wave form in hepatic artery, portal vein and hepatic veins. No patient had abnormal findings on angiographic computerized tomography. There was 1 graft failure in 20 recipients. The graft failure was primary nonfunction, and retransplantation was done. During the hospitalizations, there were no vascular complications.

CONCLUSIONS

Doppler ultrasonography can be used to evaluate postoperative vascular complications in liver transplant patients. When the operator checks postoperative Doppler ultrasonography, it is possible to differentiate between patients, and it may help to detect the vascular complications earlier.

The effect of Doppler ultrasound on early vascular interventions and clinical outcomes after liver transplantation

BACKGROUND

During the immediate postoperative period after liver transplantation (LT), postoperative bleeding and vascular complications (stenosis, thrombosis) are the two most common complications that require therapeutic decisions. Doppler ultrasound (DUS) is the established method for screening vascular patency after LT during the immediate postoperative period. The objective of our study was to evaluate the impact of DUS performed on postoperative days (POD) 1 and 2 on early vascular interventions.

METHODS

We studied 200 patients who had undergone living donor or deceased donor liver transplantation between January 2011 and March 2012. Postoperative liver DUS findings of up to POD 14, including patency of hepatic artery, portal vein, and hepatic vein, were retrieved. Patients with normal DUS findings on POD 1 and POD 2 were classified as the normal early DUS group. Patients with abnormal DUS findings at POD1 or POD2 were classified as the abnormal early DUS group. Frequency of vascular interventions was compared between the two groups. Risk factors that predict vascular interventions also were assessed.

RESULTS

On POD 1 and 2, 81.5 % (163/200) had normal DUS findings and management was not altered by subsequent DUS findings. Two patients in the normal group were found to have hepatic artery dissection and hepatic vein thrombosis on routine CT on POD 7 and received vascular intervention. DUS results in the two patients were normal until POD 6, but DUS performed after the CT on POD 7 were consistent with the CT findings. Of the 37 recipients who showed abnormal DUS findings on POD 1 or 2, the DUS findings were normalized or unchanged thereafter in 33 patients and no vascular interventions were performed. Two patients underwent hepatic artery thrombectomy on POD 2, one patient required a portal vein thrombectomy on POD 1, and one patient died on POD 3 due to bleeding. The overall incidence of vascular complication requiring vascular interventions was 2.5 %. Logistic regression identified abnormal DUS findings on POD 1 or 2 as an independent risk factor of vascular complications requiring intervention.

CONCLUSIONS

In LT recipients who demonstrate normal DUS findings in the first 2 postoperative days, additional DUS screening may have value only when clinically indicated.

Transcapsular arterial neovascularization after liver transplantation in pediatric patients indicates transplant failure

PURPOSE

To identify transcapsular arterial neovascularization with Doppler ultrasonography (US) in pediatric patients after liver transplantation and to assess the frequency of the finding, its underlying causes, and its relevance in terms of clinical outcome.

MATERIALS AND METHODS

The study was approved by the local ethics committee, with waived informed consent. All pediatric patients who underwent liver transplantation between January 2000 and December 2003 were retrospectively evaluated. Patients were followed up until June 2008, by using a predefined US protocol with prospective documentation. Of 182 consecutive liver transplantations performed in 162 patients (mean age, 4.5 years; range, 0.1-18.4 years) in this period, 25 patients with a total of 27 liver transplantations underwent US examinations conducted by multiple investigators and were primarily excluded. Student t tests and χ(2) tests were performed where appropriate. The Tarone-Ware test was used to compare transplant survival times.

RESULTS

Transcapsular arterial neovascularization was noticed in 13 of 137 patients (9.5%) and in 13 of 155 liver transplants (8.4%). The mean time until arterial neovessels appeared was 157 days after liver transplantation (median, 97 days; range, 19-477 days). Arterial neovascularization was associated with pronounced transplant malperfusion and inflammatory changes (P < .001). Patients with transcapsular arterial neovascularization had a significantly shorter mean transplant survival time (1426.4 days ± 244.5 [standard error], with 95% confidence interval: 947.23, 1905.23, vs 2526.4 days ± 92.1, with 95% confidence interval: 2345.84, 2706.97; P = .008) and a higher retransplantation rate (53.8% vs 19.7%, P = .009).

CONCLUSION

Transcapsular arterial neovascularization, detected with color Doppler US, occurred in 9.5% (13 of 137) of pediatric patients and 8.4% (13 of 155) of liver transplants and was associated with underlying malperfusion and inflammation. The diagnosis of transcapsular arterial neovascularization was associated with reduced graft survival times and a high retransplantation rate. The negative prognostic value of the sign may assist in a strategy of organ allocation.

Early hepatic artery thrombosis after liver transplantation: a systematic review of the incidence, outcome and risk factors

To clarify inconsistencies in the literature we performed a systematic review to identify the incidence, risk factors and outcome of early hepatic artery thrombosis (eHAT) after liver transplantation. We searched studies identified from databases (MEDLINE, EMBASE, Science Citation Index) and references of identified studies. Seventy-one studies out of 999 screened abstracts were eligible for this systematic review. The incidence of eHAT was 4.4% (843/21, 822); in children 8.3% and 2.9% in adults (p < 0.001). Doppler ultrasound screening (DUS) protocols varied from 'no routine' to 'three times a day.' The median time to detection was at day seven. The overall retransplantation rate was 53.1% and was higher in children (61.9%) than in adults (50%, p < 0.03). The overall mortality rate of patients with eHAT was 33.3% (range: 0-80%). Mortality in adults (34.3%) was higher than in children (25%, p < 0.03). The reported risk factors for eHAT were, cytomegalovirus mismatch (seropositive donor liver in seronegative recipient), retransplantation, arterial conduits, prolonged operation time, low recipient weight, variant arterial anatomy, and low volume transplantation centers. eHAT is associated with significant graft loss and mortality. Uniform definitions of eHAT and uniform treatment modalities are obligatory to confirm these results and to obtain a better understanding of this disastrous complication.

Infected bilomas in liver transplant recipients: clinical features, optimal management, and risk factors for mortality

BACKGROUND

Infected hepatic fluid collections (bilomas) are a major infectious complication of liver transplantation. Limited data exist on management and outcome of biloma.

METHODS

We report a cohort study of 57 liver transplant recipients with posttransplantation bilomas undertaken to identify the clinical features of biloma, management strategies, and outcome.

RESULTS

Fever (44%) and abdominal pain (40%) were the most common presenting symptoms, but one-third of patients were asymptomatic; 79% had elevated hepatic enzyme levels. Patients without hepatic artery thrombosis (HAT) had the highest rates of resolution with percutaneous drainage and anti-infective therapy (64%). Retransplantation was necessary in 64% of patients with HAT and biloma. Independent predictors of resolution with nonsurgical therapy were absence of HAT (odds ratio [OR] 7.69; P=.01) and absence of Candida (OR, 9.09; P=.02) or enterococcal infection (OR, 7.69; P=.03). Patients with bilomas had significantly greater mortality (Cox proportional hazard ratio [HR], 2.38; P=.008, by log rank test) and graft loss (HR, 4.31; P<.0001). Predictors of mortality by multivariable analysis included renal insufficiency (OR, 12.51; P=.02) or infection with Candida species (OR, 4.93; P=.03) or gram-negative bacilli (OR, 9.12; P=.01).

CONCLUSION

Posttransplantation biloma should be suspected in patients with fever or abdominal pain or abnormalities of hepatic enzymes, and it can be confirmed by computerized tomography and radiographically guided aspiration. Bilomas are most likely to be successfully treated nonsurgically in patients without HAT and without Candida or enterococcus infection.

Interventional Radiology in the Pediatric Liver Transplant Patient

Liver transplantation now plays a major role in the treatment of end-stage liver disease in children. Reduced-size liver transplant surgical techniques have allowed increasing numbers of children to undergo liver transplantation. As more children are undergoing liver transplantation, there is a growing need for radiologic diagnosis of and intervention in post-transplantation complications in these patients.

Hepatic allograft abscess with hepatic arterial thrombosis

BACKGROUND

Intrahepatic abscess (IA) is an uncommon complication after liver transplantation (OLTx) usually found in the setting of hepatic arterial thrombosis (HAT) often with associated biliary tree necrosis and/or stricture. Conventional treatment of IA in this setting has required retransplantation.

METHODS

A retrospective review of 274 patients (287 OLTx) from September 1991 through September 1996 was performed. Median follow-up was 3.6 years. Diagnosis of HAT was confirmed by arteriography and IA was documented by computerized tomography. Percutaneous drainage of the abscess and stenting of biliary strictures, if present, was achieved using conventional interventional radiology techniques.

RESULTS

The diagnosis of hepatic artery complication was made in 14 patients (5.1%), 2 of whom required retransplantation. Hepatic artery thrombosis associated with solitary IA was found in 3 patients (1%) who were transplanted in our center and in 1 additional patient followed up at our center but transplanted elsewhere. All 4 patients had complete resolution of IA using this approach. Three of the 4 patients are alive and well, with the fourth patient succumbing to recurrent hepatitis B infection resulting in allograft failure.

CONCLUSIONS

Solitary hepatic allograft abscesses associated with HAT respond to percutaneous drainage and antibiotics, obviating the need for retransplantation in this setting.

Biphasic spiral computed tomography versus digital subtraction angiography for evaluation of arterial thrombosis after orthotopic liver transplantation

RATIONALE AND OBJECTIVES

The authors characterize the spiral computed tomographic (CT) findings in patients with hepatic arterial thrombosis after orthotopic liver transplantation (OLT).

METHODS

In nine with and 15 patients without hepatic artery thrombosis (HAT) after OLT, unenhanced and contrast-enhanced biphasic spiral CT was performed during arterial and venous phases, and evaluated by consensus of two blinded readers. Evaluation included signs of parenchymal and vascular changes in the liver. Findings subsequently were correlated with those of digital subtraction angiography (DSA).

RESULTS

Among all patients, eight had complete occlusion of the proximal hepatic artery and one patient had partial thrombosis, as revealed by conventional DSA. Characteristic CT findings of HAT included irregularly shaped confluent hypoattenuating liver areas (n = 8), seen both before and after administration of contrast material. Necrotic lesions and changes consistent with ischemic type of biliary lesion were documented in six patients. Biphasic CT allowed detection of HAT in eight patients. Because of inadequate contrast enhancement during the arterial phase, thrombosed intrahepatic arteries were not adequately diagnosed in one patient. Overall CT sensitivity to detect HAT was 89%, specificity was 100%.

CONCLUSIONS

Characteristic biphasic spiral CT findings in hepatic artery thrombosis contribute to early detection of arterial thrombosis after OLT and are helpful for planning more invasive diagnostic approaches.

Inter-observer variability of portal hemodynamics measured by Doppler ultrasound on three different locations of portal vein

Doppler ultrasound is a noninvasive modality for portal hemodynamic study. However, inter-observer variability has been observed. This study has investigated ways to produce less inter-observer variability. Doppler ultrasound portal vein hemodynamic studies were carried out by three well-trained specialists on 20 healthy hospital staff members. The intra-hepatic, first branch, right portal vein, the hilar portal vein, and the extra-hepatic portal vein were chosen for study. With respect to the diameter of portal veins, a significant inter-observer variability was found for the first branch right portal vein and the extra-hepatic portal vein, but not for the hilar portal vein. For maximal portal vein velocity studies, inter-observer variability was not found at any location. A significant failure rate was noted for the measurement of extra-hepatic portal vein velocity. Only 8 volunteers had complete data from all of the three investigators. A significant variability was also noted for the average velocity of extra-hepatic portal vein. We conclude that Doppler ultrasound hemodynamic studies of the hilar portal vein has the most acceptable inter-observer variability and thus should be used for longitudinal portal hemodynamic studies.

Partial liver transplantation from a living donor: experimental research and clinical experience

Partial liver transplantation (PLTR) was studied experimentally, using 60 monkeys (20 recipients, 20 donors, 20 blood donors). The left lobe of the donors was transplanted orthotopically, using a veno-venous bypass catheter that was inserted in the portal vein and the other side passed through the hepatic portion of the inferior vena cava. The donor survival rate at 1 week was 70%. Seven recipients survived for more than 58 hours (58, 60, 64, 68, 72, 110, and 252 hours), and 13 died within 48 hours of surgery because of postoperative complications. Clinical living related liver transplantation (LRLT) was performed between June 1990 and March 1992 on six patients with biliary atresia and on one with liver cirrhosis and hepatocellular carcinoma. In all, the father's left lobe was transplanted orthotopically. Cyclosporine, azathioprine, and methyl prednisolone were administered. In addition, FK-506 was given to two patients in whom rejection was observed; one died 37 days after surgery because of acute rejection followed by systemic cytomegalovirus infection. The other six patients have survived for 8 to 29 months since transplantation. All six have been discharged from the hospital and are enjoying normal daily life. The postoperative course of all donors was uneventful. They were discharged 2 weeks after the operation and returned to their jobs in 2 months. The authors conclude that PLTR from a living donor is a promising therapeutic alternative to liver transplantation from a cadaver.

Ultrasound-guided pediatric liver transplant biopsy using a spring-propelled cutting needle (biopsy gun)

Biopsy is the best way to diagnose allograft rejection, the most common complication following liver transplantation. The authors reviewed 99 consecutive ultrasound-guided cutting needle biopsies in 19 infants and children. Conscious sedation was used with 95 biopsies. General anesthesia was used with four biopsies, all in patients undergoing percutaneous biliary procedures at the same time. Ninety-eight biopsies were diagnostic. Only one major complication occurred: biloma. Ultrasound-guided cutting needle biopsy of pediatric liver transplant patients can be performed safely and efficaciously.

Abdominal CT following liver transplantation

Computed tomography (CT) is one of several imaging modalities employed in the evaluation of complications following orthotopic liver transplantation. Abdominal CT scans were performed in 92 (48%) of the first 190 liver transplant patients at our institution. These studies were retrospectively reviewed to determine the indications for CT in this population and to determine the incidences of the various CT findings. The major indication (70%) was detection of bile leakage, hemorrhage, or abscess. The role of CT was primarily to discover such abnormal fluid collections and guide their percutaneous drainage. This article describes a wide spectrum of common and uncommon findings following liver transplantation and illustrates their CT features.

Duplex Doppler ultrasound for the detection of vascular occlusion following liver transplantation in children

Sixty-three children and adolescent patients who received 78 consecutive orthotopic liver transplants and had serial duplex ultrasound monitoring were retrospectively reviewed for episodes of occlusion of the hepatic artery or portal vein. There were 13 documented episodes of complete occlusion of the main hepatic artery or a major branch, of which nine were diagnosed by the absence of flow during duplex ultrasound examination. Four occlusions were not detected, two affected hepatic artery branches, one an accessory hepatic artery, and one the main hepatic artery. The overall sensitivity of the method was 69% and specificity 100%. Six portal vein occlusions were documented in five patients and all six were successfully diagnosed on ultrasound examination, giving a sensitivity and specificity of 100%. Three of the patients had simultaneous occlusions of both vessels. In the early post-operative period duplex Doppler ultrasound examination has proved an effective non-invasive method for the detection of vascular occlusion, but is not yet sensitive enough to replace angiography fully for the detection of hepatic artery occlusion, particularly when this occurs distal to the main hepatic artery.

Biliary complications after transplantation in children: role of imaging modalities

Among a series of 140 liver transplantations in children, 21 biliary complications (BC) (15%) are reported. BC were identified from 2 days to 3 months after LT. Positive US findings were present in 20 cases. Cholangiography was obtained by opacification of a surgical drain in 3 cases, per-operatively in 3 and by PTC in 15. Drainage was placed in 9 and balloon dilatation performed in 2. Causes of BC include hepatic artery (HA) thrombosis in 7, HA stenosis in 1, anastomosis stricture in 7, anastomosis kink in 3, mucocele of cystic duct remnant in 2 and sludge in 1. Treatment was surgical in all, but 2 cases were treated percutaneously. There is a great difference in severity of prognosis between complications secondary to HA thrombosis and isolated BC. Role of US in diagnosis and of PTC and interventional radiology in treatment are emphasized.