Y.C Chiang

Magnetic resonance of the hepatic veins with angular reconstruction: application in living-related liver transplantation.

BACKGROUND Preoperative mapping of the hepatic venous system of the partial liver graft is indispensable to the success of living-related liver transplantation. We assessed the accuracy of magnetic resonance (MR) venography with angular reconstruction in depicting the tributaries of the middle hepatic vein and left hepatic vein in the donors, which was essential in graft retrieval and venoplasty. METHODS Nineteen living-related liver transplantation donors underwent a pretransplantation survey, including sonography and MRI for hepatic venous evaluation. T1-weighted images were reconstructed manually, using the inferior vena cava as a fixed point for tilting to produce an oblique plane image where both the middle hepatic vein and left hepatic vein could be demonstrated draining into the inferior vena cava. The reconstructed images of the hepatic veins were compared with preoperative sonography, intraoperative sonography, and operative findings. RESULTS Preoperative sonography and MR findings correlated well with the operative findings in the major hepatic veins. The MR venography of the ramification of the hepatic veins has an accuracy of 93%, the sonography, 84%. Sonography is slightly inferior in the evaluation of the hepatic vein in segment 4 and the left superior hepatic vein, with an accuracy of 73% and 67%, respectively. CONCLUSION MR venography with angular reconstruction is accurate in depicting the complex distribution of the hepatic veins of the left liver, providing important information for decision making as to the cutting plane during graft retrieval and the method of venoplasty and anastomosis. Thus, unnecessary blood loss could be avoided and vascular complications could be prevented, as these conditions would be unacceptable for a healthy living donor. We propose that MR venography, a rapid and reliable technique, is an appropriate alternative examination or complementary modality to sonography in the pretransplantation evaluation of the living donor.

Outcome of living donor liver transplantation for glycogen storage disease.

GLYCOGEN storage diseases (GSD) are inherited disorders in which the amount and/or structure of glycogen in body tissues are abnormal. GSD I (von Gierke disease) is caused by a deficiency of glucose 6-phosphatase activity in the liver, kidney, and intestinal mucosa with glycogen overloading in these organs. The clinical manifestations are seizures, systemic acidosis, hyperlipidemia, hyperuricemia, and growth retardation. Without effective treatment, long-term complications occur, including gout, osteoporosis, short stature, and hepatic adenomas. GSD III (Cori disease) is caused by a deficiency of glycogen debranching enzyme activity and characterized with limit dextrin-like glycogen accumulated in both liver and muscle in most patients. Hepatomegaly, hypoglycemia, hyperlipidemia, and growth retardation are the main manifestations in children; while liver cirrhosis and /or hepatocellular carcinoma may occur later. Great progress in the management of GSD I and III has been made recently. For patients affected with GSD I, nocturnal nasogastric feeding of glucose or orally administered uncooked cornstarch is effective. With early diagnosis and initiation of treatment, normal growth and development may be expected. Some patients are free of long-term complications. Treatment of GSD III consists of highprotein diet, and frequent high carbohydrate meals for patients with hypoglycemia. Nocturnal gastric feeding or cornstarch supplements comprise effective therapy. However, some patients with GSD do not respond to diet therapy and may need frequent intravenous glucose infusions and even parenteral nutrition to maintain metabolic homeostasis. Liver transplantation (LT) is considered to correct the metabolic defects and the deleterious complications of GSD. LT for GSD I and III was first reported, respectively, by Malatack et al in 198 and by Superina et al in 1989. We present five cases of GSD (four GSD Ia; one GSD III), which were treated by living donor liver transplantation (LDLT) in our institution. These patients were unresponsive to medical therapy or developed serious complications of GSD. In this study we investigate the outcome of these children after LDLT for GSD. PATIENTS AND METHODS

Multislice computed tomography angiography in pediatric liver transplantation.

Background. Preoperative delineation of any vascular anomalies offers planning for possible alteration of surgical procedures, especially in pediatric recipients undergoing living-related liver transplantation. Purpose. We assess the efficacy of three-dimensional (3D) multislice computed tomography (CT) angiography in the hope of replacing conventional angiography as the pretransplant evaluation of the hepatic vascular system for potential recipients of liver transplantation. Methods. 3D CT angiography was performed in 38 children with biliary atresia. Conventional angiography was also performed in the first 15 patients. Twelve patients underwent living-related liver transplantation. The findings on 3D CT angiography were compared with conventional angiography and operative findings. Results. 3D CT angiography was successfully performed in 37 pediatric patients. All findings of 3D CT angiography on hepatic artery, portal vein, and inferior vena cava paralleled those of catheter angiography and operative findings. Four patients were unsuitable to receive living grafts because of pathologic insults of the hepatic artery (one patient) and the portal vein (three patients). Three patients were advised to undergo a venous graft for portal anastomoses. Eight patients demonstrated portosystemic shunts that may require closure. Conclusion. 3D CT angiography proves to be a better tool in the demonstration of the vascular system and identification of pathologic insults in pediatric patients. It is superior to conventional angiography because it is less invasive, more convenient, and more efficient in providing thorough preoperative information that would have a major impact on patient selection and surgical planning.

Soluble thrombomodulin antigen as a marker for endothelial damage during liver transplantation.

RTHOTOPIC liver transplantation (OLT) is now being performed with improved survival rates in a high number of patients suffering from different liver diseases. Despite better control of blood loss, hemorrhages still occur, particularly after reperfusion. Problems arising from defective hemostasis during major abdominal surgery are a major risk for patients with terminal chronic liver disease. 1 Liver transplantation, most often performed in such patients, differs from operations because the recipients start with a diseased liver and end up with a healthy liver, the function of which, however, is compromised by preservation damage. Thrombomodulin (TM), an integral glycoprotein on the surface of endothelial cells, serves as a receptor for thrombin. Thrombin bound to TM greatly reduces procoagulatory and platelet-stimulating effects but activates the zymogen, protein C. 2 Activated protein C together with protein S inactivates two blood coagulation cofactors, factor Va and factor VIIIa, and indirectly stimulates fibrinolysis. Thus, TM plays an important role as an anticoagulant protein on the blood vessel wall. Immunohistochemically, TM has been found to be mainly present on endothelial cell surfaces of blood and lymphatic vessels in all organs except the brain. 3,4 A smaller from of TM, the soluble thrombomodulin (sTM), has been isolated from human blood and urine. 5 The structure of sTM is not known but is thought to be similar to the soluble protein obtained after proteolytic modification of TM with elastase 6 —a cleaved form of tissue TM with loss of part of the transmembrane domain, and the cytoplasmatic tail. 7 Therefore, sTM in plasma appears to be derived from injured endothelial cells or to be proteolytically cleaved from TM by proteases. In vitro, sTM has been shown to be a marker of endothelial damage 8 and several previous clinical studies have shown that plasma levels of sTM are increased in various diseases associated with endothelial cell damage or proteolytic activity on the endothelial cell surface, including DIC, 9,10 adult respiratory distress syndrome (ARDS), 10 thromboembolic disease, 9,10 thrombotic thrombocytopenic purpura, 11,12 diabetes mellitus with microangiopathy, 9,13 systemic lupus erythematosus (SLE), 14 and chronic myelogenous leukemia. 15 Because they are usually associated with vascular endothelium alterations, 10,16 TM plays an important role as an anticoagulant protein on the blood vessel wall. However, in the context of liver transplantation, the understanding of pathophysiology of TM in the coagulation-fibrinolysis equilibrium is still in its infancy. There are only few reports 17,18 on sTM in liver transplantation. In orthotopic liver transplantation, both platelet and leukocyte activation as well as prothrombin activation are suspected of being caused by damaged endothelial cells in the grafted liver. In this study, plasma sTM levels as an endothelial marker were measured in the course of 11 consecutive liver transplantation. Samples were taken at nine different time points perioperatively as well as the perfusate released from the graft outflow vein during the flushing procedure.

Initial experience with right lobe living donor liver transplantation

THE feasibility of right lobe living donor liver transplantation (LDLT) has been demonstrated and its practice is gaining popularity. Although the supply of organs is not enough the world over, LDLT is probably more warranted in societies where cadaveric donation is severely restricted. Such is the situation in Taiwan with only 0.5 liver grafts available per million population per year (data from the Organ Donation Association, Taiwan). Whereas the left lateral segment is usually enough for pediatric recipients, a bigger graft would be required for larger pediatric or adult candidates to provide adequate functional mass. The Liver Transplant Program of the Chang Gung Memorial Hospital caters to both adult and pediatric recipients and its living donor program, which began in 1994, has thus far been limited to left lobe allografting. This report aims to describe an initial experience with right lobe LDLT in this institution, which is also the first of its kind in Taiwan. The recipient was a 17-year old male weighing 63 kg with end-stage liver cirrhosis secondary to Wilson’s disease who suffered frequent variceal bleeding. The donor was his 42-year-old father weighing 56 kg who was blood group identical. With the size discrepancy between father and son, a right lobe graft was the better option to provide a graft-recipient weight ratio of at least 1%. Preoperative imaging studies revealed complicated right lobe hepatic venous anatomy in the donor with two right hepatic veins (RHV), two middle hepatic veins (MHV), and two right inferior hepatic veins (RIHV). There were likewise two right hepatic ducts, one of them a right posterior segment duct draining into the left hepatic duct. An extended right lobectomy including the MHV was performed in the father and the operation lasted for 12 hours with a blood loss of 110 mL. The procedure was well tolerated and the donor was discharged on the seventh postoperative day without any complications. The graft weighed 798 g and the graft-recipient ratio was 1.3%. Graft implantation was done with preservation of the inferior vena cava (IVC) without crossclamping. Venoplastics of the two RHVs and two MHVs in the graft to create a single outflow orifice for each main hepatic vein was performed and anastomosed to the recipient RHV and common trunk of MHV and left hepatic vein (LHV), respectively. The smaller (3 mm) of the two RIHVs was ligated and the larger one (5 mm) was anastomosed to a separate venotomy on the IVC. Right-to-right portal vein and hepatic artery anastomoses were made. The two bile ducts were close to each other and anastomosed as one Roux-en-Y hepatodochojejunostomy. Graft function was good although massive ascites of up to 2 L/d persisted. The recipient had recurrent variceal bleeding 1 week posttransplant, which was successfully managed by band ligation. Biopsy-proven acute cellular rejection was diagnosed on the 19th day posttransplant and was effectively treated with three boluses of intravenous steroids. He was on cyclosporine-based triple drug immunosuppression. Hepatic outflow obstruction was suspected and suggested by Doppler ultrasound which revealed poorly detectable hepatic veins with velocities of 11 to 16 cm/sec and flat to borderline biphasic waveforms. The portal vein and hepatic artery exhibited good flow. Computed tomography showed congestion of segment 7 of the liver while longitudinal magnetic resonance imaging showed narrowing of the MHV anastomosis. Percutaneous venography with pressure studies demonstrated significant gradients across the RHV and MHV compatible with outflow obstruction. The RHV stricture was dilated by balloon angioplasty while the MHV stenosis was not corrected by dilatation alone. The narrowing was believed to be due to torsion and was corrected by deployment of a Wallstent metallic prosthesis (12 3 50 mm, Wallstent, Schneider, Switzerland). Pressure gradients dropped from 17 to 14 cmH2O and from 34 to 12 cmH2O in the RHV and MHV, respectively. Doppler ultrasound demonstrated a marked increase in flow velocities and a change from monophasic to biphasic waveforms in the hepatic veins after the interventional procedures. The ascites gradually decrease after venoangioplasty of the RHV and stenting of the MHV and the patient’s overall condition improved until discharge 1 month after the procedure. At 8 months posttransplant the patient continues to do well with normal liver function. The latest CT

THE SIGNIFICANCE OF HEPATIC VEIN OUTFLOW VOLUME IN HEPATIC OUTFLOW INSUFFICIENCY OF LIVING RIGHT LIVER GRAFT EVALUATED BY COLOR DOPPLER ULTRASOUND

The color Doppler ultrasound has been used to evaluate hepatic vein (HV) outflow insufficiency based on flow velocity and waveforms. In our experience, some cases with flat waveforms are clinically asymptomatic. The parameters of HV flow velocity and waveforms are not always correlated with clinical problems. So, we proposed that total HV flow volume (HVFV) may be a more reliable index. From August 2001 to July 2003, 31 cases among 48 adult-to-adult living related transplants of a right liver graft had one HV anastomosis. HV velocity, waveforms, and HVFV were compared both before and after transplantation. We set the minimal HVFV ratio at 80% based on the original HVFV before graft retrieval. There was no significant difference in HVFV before liver graft retrieval between the 2 groups, but there was a significant change after transplantation. There were no cases of HV insufficiency among group A patients (>80%), whose HVFV ranged from 397 to 1181 mL/min with ratios from 75% to 180% (mean 115%). In group B, there were 4 complicated cases with prolonged severe ascites (<80%) with HVFV ratios from 56% to 76% (mean 66%). Fisher exact test showed a great significance (P < .001). Thus the preliminary criteria of 80% minimal HVFV ratio allows detection of HV insufficiency for further interventional management.