Tai Yi Chen

Assessment of donor fatty livers for liver transplantation

Aim. The effect of fatty liver on graft survival, especially with reference to macrovesicular and microvesicular steatosis, is still uncertain. This preliminarily study was designed to create a noninvasive method for the quantification of the hepatic fat content in vivo and to establish provisional criteria for the assessment of fatty donor livers before liver transplantation among transplant surgeons, radiologists, and pathologists. Methods and Materials. Different degrees of rat fatty liver model were established by feeding rats a diet deficient in choline and methionine for different periods of time. Computed tomography (CT) with test tubes containing variable percentages of fat equivalent substance were used to assess the severity of fatty change of the rat liver. This was then correlated with the histological classification, level of hepatic enzymes, and graft survival. Results. Linear correlation between the fat volume fraction added to the test tubes and CT density were found. The process of producing a fatty liver via diet alteration peaked at week 3. At this time hepatic enzymes, radiological fat content, and posttransplantation survival were worse (P =0.013), compared with other time points. Radiological assessment of fatty liver correlated well with survival and serum glutamic oxaloacetic transaminase and glutamic pyruvate transaminase levels. Conclusion. Severe microvesicular steatosis does not influence recipient survival, however, macrovesicular steatosis affects graft survival. Caliber CT is a practical and simple method that allows an accurate noninvasive quantitative assessment of hepatic fatty infiltration. It has potential to be a useful parameter for the assessment of donor livers for clinical liver transplantation.

Risk factors for intraoperative portal vein thrombosis in pediatric living donor liver transplantation.

Abstract:u2002 Pathologic changes of the recipient native portal venous system may cause thrombosis of the portal vein, especially in pediatric living donor liver transplantation (LDLT). This study assessed the utility of Doppler ultrasound (US) for the detection of intraoperative portal vein occlusion and identification of predisposing risk factors in the recipients. Seventy‐three pediatric recipients who underwent LDLT at Chang Gung Memorial Hospital, Taiwan, from 1994 to 2002 were included. Preoperative and intraoperative Doppler US evaluation of the portal vein was performed. Age, body weight, native liver disease, type of graft, graft recipient weight ratio (GRWR), type of portal anastomosis, portal velocity, portal venous size and presence of portosystemic shunt were analyzed for statistical significance of predisposing risk factors. Eight episodes of intraoperative portal vein thrombosis, with typical findings of absent Doppler flow in portal vein and prominent hepatic artery with a resistant index lower than 0.5 (pu2003<u20030.001), were detected during transplantation, which was then corrected by thrombectomy and re‐anastomosis. Children age ≤1u2003yr (pu2003=u20030.025), weight ≤10u2003kg (pu2003=u20030.024), low portal flow ≤7u2003cm/s (pu2003=u20030.021), portal venous size ≤4u2003mm (pu2003=u20030.001), and GRWR >3 (pu2003<u20030.017) were all risk factors for intraoperative portal vein thrombosis. Doppler US is essential in the preoperative evaluation, early detection and monitoring of outcome of the portal vein in liver transplant.

Treatment of Complicated Hepatolithiasis with Intrahepatic Biliary Stricture by Ductal Dilatation and Stenting: Long-term Results

Abstract. A group of 190 cases of hepatolithiasis with postoperative residual stones located proximal to the stricture sites were managed with the aim of complete clearance of stones and relief of bile stasis to decrease the potential risk of recurrence. All procedures were performed through a T-tube track with gradual dilatation and stent placement through the stricture sites, creating a channel that allows cholangioscopy and electrohydraulic lithotripsy. Complete clearance of intrahepatic duct (IHD) stones was achieved in 88.4% of cases. Multiple sharply angulated IHD strictures in right-sided hepatolithiasis constituted a major cause of failure. Recurrent stone formation and repeated cholangitis, subsequent drainage, and liver resection are associated with high mortality rates particularly if there is late development of a cholangiocarcinoma. We concluded that postoperative ductal dilatation and stenting through the T-tube track combined with endoscopic electrohydraulic lithotripsy is effective and safe for managing complicated hepatolithiasis. Persistent irreversible aneurysmal dilatation of IHD and atrophic change of the affected hepatic lobe at follow-up were ominous signs of recurrence and cholangiocarcinoma development. Early drainage with stone extraction combined with surgical intervention can prevent subsequent morbidity and mortality.

3DCT angiography for detection of vascular complications in pediatric liver transplantation

Catheter angiography for early diagnosis of vascular complications in pediatric liver transplant yields excellent results but remains an extremely invasive examination for younger children, precluding its routine use. We assessed the efficacy of three‐dimensional multislice computed tomographic angiography (3DCTA) as an alternative option in these patients. Methods Twenty children suspected of vascular complications on clinical grounds, laboratory findings, or Doppler ultrasound underwent 3DCTA between April 2000 and April 2003. Interventional procedures via conventional angiography were subsequently performed in 5 cases, thrombolytic therapy in 4, surgical in 1, and conservative treatment in 10. Results Two hepatic artery stenosis,1 hepatic artery thrombosis, 5 hepatic vein stenosis, 4 portal vein occlusion, 1 portal vein stenosis, and 7 non‐vascular lesions were detected, all of which paralleled the findings of catheter angiography, Doppler ultrasound, and operations. The diagnostic accuracy for vascular complication was 90%. The sensitivity and specificity were 86.7% and 100%, respectively. The positive and negative predictive values were 100% and 71.4%, respectively. To date 19 patients are alive, with a median follow‐up period of 24.8 months. In conclusion, 3DCTA is accurate and efficient in the identification of pathological vascular insults and offers essential information for major decision on further management of the vascular complications in pediatric recipients of liver transplant. (Liver Transpl 2004;10:248–252.)

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

BACKGROUNDnPreoperative 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.nnnMETHODSnNineteen 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.nnnRESULTSnPreoperative 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.nnnCONCLUSIONnMR 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.

Angioplasty treatment of hepatic vein stenosis in pediatric liver transplants: long-term results

We reviewed long‐term results of percutaneous venoplasty in children with hepatic vein stenosis after partial liver transplants, of which excellent early results were shown. Percutaneous transjugular hepatic venoplasty using balloon dilatation or stent implantation was performed in six cases with hepatic vein stenosis identified on routine post‐transplant Doppler sonography and confirmed by transjugular hepatic venography from 1994 to 2003. Repeated procedure was carried out if necessary. Six of 105 patients with partial liver graft developed hepatic stenosis characterized by low hepatic venous velocity with monophasic waveform with significant pressure gradient (>5u2003mmHg). The incidence was 4.46% for all 112 pediatric liver transplants. Successful balloon venoplasty was achieved in four cases. Self‐expanding stent was used in two cases with absent waisting or angulated balloon catheter during dilatation and persisted pressure gradient (>5u2003mmHg). Repeated procedure was required in two initially successful cases with additional stent used in one case. Three cases had transient hyperdynamic hepatic venous flow with markedly increased central venous pressure after stent implantation. Nonprocedural‐related mortality rate was 16.7%. Patent hepatic vein was maintained in five patients after a mean follow‐up of 3.67u2003years (0.75–9.5). Higher incidence of hepatic vein stenosis was noted in pediatric partial liver transplant. However, encouraging long‐term results showed that hepatic venoplasty or stent implantation could be a preferable alterative to surgical revision or retransplantation, which has been the procedure of choice in our hospital.

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.