Leo Leung-Chit Tsang

Prophylactic intraoperative uterine artery embolization to control hemorrhage in abnormal placentation during late gestation

OBJECTIVE To determine whether prophylactic intraoperative uterine artery embolization (UAE) reduces blood loss and minimizes morbidity and mortality in cases of placenta accreta, increta, and percreta. DESIGN A prospective, nonrandomized clinical trial. SETTING A university-based, high-risk pregnancy unit and department of interventional radiology. PATIENT(S) Eleven patients who were diagnosed prenatally with placenta accreta, increta, and percreta. INTERVENTION(S) Patients with suspected placenta accreta were treated with prophylactic, intraoperative UAE immediately after fetal delivery and before removal of the placenta. Patients with suspected placenta increta were treated with UAE; the placenta remained in situ, or a hysterectomy was performed. Patients with suspected placenta percreta were treated with UAE, and the placenta remained in situ. MAIN OUTCOME MEASURE(S) Intraoperative blood loss, maternal mortality, fetal mortality, need for hysterectomy. RESULT(S) Eleven viable fetuses were born with no radiation exposure. There were no maternal or fetal mortalities. Nine of 11 patients had an estimated blood loss between 500 and 2300 mL. Emergency hysterectomy was performed in two patients because of massive bleeding. The complications, including peritonitis and endometritis, occurred in another two patients after embolization. CONCLUSION(S) Prophylactic, intraoperative UAE before placental expulsion appears to reduce the risk of postpartum hemorrhage, decrease morbidity and mortality, and increase the chance of preservation of the uterus in patients with placenta accreta, increta, and percreta.

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

Abstract:  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 (p < 0.001), were detected during transplantation, which was then corrected by thrombectomy and re‐anastomosis. Children age ≤1 yr (p = 0.025), weight ≤10 kg (p = 0.024), low portal flow ≤7 cm/s (p = 0.021), portal venous size ≤4 mm (p = 0.001), and GRWR >3 (p < 0.017) 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.

Preoperative Imaging Evaluation of Potential Living Liver Donors: Reasons for Exclusion From Donation in Adult Living Donor Liver Transplantation

Accurate pretransplant evaluation of a potential donor in living donor liver transplantation (LDLT) is essential in preventing postoperative liver failure and optimizing safety. The aim of this study was to investigate the reasons for exclusion from donation of potential donors in adult LDLT. From September 2003 to June 2006, 266 potential donors were evaluated for 215 recipients: 220 potential donors for 176 adult recipients; 46 for 39 pediatric recipients. Imaging modalities including Doppler ultrasound, computerized tomography (CT), and magnetic resonance (MR) angiography provided vascular evaluation and MR cholangiopancreatography to evaluate biliary anatomy. Calculation of liver volume and assessment of steatosis were performed by enhanced and nonenhanced CT, respectively. In the adult group, only 83 (37.7%) potential donors were considered suitable for LDLT. Of the 137 unsuitable potential donors, 36 (26.2%) candidates were canceled because of recipient issues that included death of 15 recipients (10.9%), main portal vein thrombosis (8%), recipient condition beyond surgery (5%), and no indication for liver transplantation due to disease improvement (2%). The remaining 101 (73.8%) candidates who were excluded included steatosis (27.7%), an inadequate remnant volume (57.4%), small-for-size graft (8.9%), HLA-homozygous donor leading to one-way donor-recipient HLA match (3%), psychosocial problems (4%), as well as variations of hepatic artery (4%), portal vein (1%), and biliary system anatomy (5%). Anatomic considerations were not the main reason for exclusion of potential donors. An inadequate remnant liver volume (< 30%) is the crucial point for the adult LDLT decision.

Liver graft-to-recipient spleen size ratio as a novel predictor of portal hyperperfusion syndrome in living donor liver transplantation.

Portal hyperperfusion in a small‐size liver graft is one cause of posttransplant graft dysfunction. We retrospectively analyzed the potential risk factors predicting the development of portal hyperperfusion in 43 adult living donor liver transplantation recipients. The following were evaluated: age, body weight, native liver disease, spleen size, graft size, graft‐to‐recipient weight ratio (GRWR), total portal flow, recipient portal venous flow per 100 g graft weight (RPVF), graft‐to‐recipient spleen size ratio (GRSSR) and portosystemic shunting. Spleen size was directly proportional to the total portal flow (p = 0.001) and RPVF (p = 0.014). Graft hyperperfusion (RPVF flow >250 mL/min/100 g graft) was seen in eight recipients. If the GRSSR was <0.6, 5 of 11 cases were found to have graft hyperperfusion (p = 0.017). The presence of portosystemic shunting was significant in decreasing excessive RPVF (p = 0.059). A decrease in portal flow in the hyperperfused grafts was achieved by intraoperative splenic artery ligation or splenectomy. Spleen size is a major factor contributing to portal flow after transplant. The GRSSR is associated with posttransplant graft hyperperfusion at a ratio of <0.6.

Hepatocellular Carcinoma Downstaging in Liver Transplantation

BACKGROUND Hepatocellular carcinoma (HCC) is the leading malignant tumor in Taiwan. The majority of HCC patients are diagnosed in late stages and therefore in eligible for potentially curative treatments. Locoregional therapy has been advocated as an effective treatment for patients with advanced HCCs. PURPOSE The aim of this study was to evaluate the outcomes of HCC downstaged patients after locoregional therapy to allow eligibility for liver transplantation. METHODS AND MATERIALS From January 2004 to June 2010, 161 patients with HCCs underwent liver transplantation including 51 (31.6%) who exceeded the University of California-San Francisco (UCSF) who had undergone successful locoregional therapy to be downstaged within these criteria. Among the downstaged patients, 48 (94.1%) underwent transarterial embolization; 7 (13.8%), percutaneous ethanol injection; 24 (47.1%), radiofrequency ablation; 15 (29.4%), surgical resection, and 34 (66.7%), combined treatment. RESULTS The overall 1- and 5-year survival rates of all HCC patients (n=161) were 93.2% and 80.5%. The overall 1- and 5-year survival rates of downstaged (n=51) versus non-downstaged (n=110) subjects were 94.1% versus 83.7% and 92.7% versus 78.9%, respectively (P=.727). There are 15 (9.2%) HCC recurrences. The overall 1- and 5-year tumor-free rates of all HCC patients were 94.8% and 87.2%. The overall 1- and 5-year tumor-free rates between downstaged versus non-downstaged patients were 93.9% and 90.1% versus 95.2% and 86.0%, respectively (P=.812). CONCLUSION Patients with advanced HCC exceeding the UCSF/Milan criteria can be downstaged to fit the criteria using locoregional therapy. Importantly, successfully downstaged patients who are transplanted show excellent tumor-free and overall survival rates, similar to fit-criteria group.

Liver graft regeneration in right lobe adult living donor liver transplantation.

Optimal portal flow is one of the essentials in adequate liver function, graft regeneration and outcome of the graft after right lobe adult living donor liver transplantation (ALDLT). The relations among factors that cause sufficient liver graft regeneration are still unclear. The aim of this study is to evaluate the potential predisposing factors that encourage liver graft regeneration after ALDLT. The study population consisted of right lobe ALDLT recipients from Chang Gung Memorial Hospital‐Kaohsiung Medical Center, Taiwan. The records, preoperative images, postoperative Doppler ultrasound evaluation and computed tomography studies performed 6 months after transplant were reviewed. The volume of the graft 6 months after transplant divided by the standard liver volume was calculated as the regeneration ratio. The predisposing risk factors were compiled from statistical analyses and included age, recipient body weight, native liver disease, spleen size before transplant, patency of the hepatic venous graft, graft weight‐to‐recipient weight ratio (GRWR), posttransplant portal flow, vascular and biliary complications and rejection. One hundred forty‐five recipients were enrolled in this study. The liver graft regeneration ratio was 91.2 ± 12.6% (range, 58–151). The size of the spleen (p = 0.00015), total portal flow and GRWR (p = 0.005) were linearly correlated with the regeneration rate. Patency of the hepatic venous tributary reconstructed was positively correlated to graft regeneration and was statistically significant (p = 0.017). Splenic artery ligation was advantageous to promote liver regeneration in specific cases but splenectomy did not show any positive advantage. Spleen size is a major factor contributing to portal flow and may directly trigger regeneration after transplant. Control of sufficient portal flow and adequate hepatic outflow are important factors in graft regeneration.

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.)

Portal vein thrombosis in biliary atresia patients after living donor liver transplantation

BACKGROUND Vascular complications are major complications after living donor liver transplantation (LDLT), especially in biliary atresia (BA). Early diagnosis and treatment of portal vein thrombosis (PVT) may ensure optimal graft function and good recipient survival. Our aim was to find any association between pre- and post-transplant anatomic characteristics and hemodynamics, and the occurrence of post-transplant PVT in BA patients undergoing LDLT. METHODS We evaluated the pre- and post-transplant findings in ultrasonography in 105 BA recipients who underwent primary LDLT to determine the possible associated factor(s) and ultrasonographic warning sign(s) that may cause PVT development after LDLT. RESULTS There were 53 male and 52 female recipients. The mean age, height, and weight were 2.8 years, 83.6 cm, and 12.5 kg, respectively. Occlusion of the portal vein (PV) developed in 8 patients. On multivariate analysis, the only independent, pretransplant risk factor predisposing to PV occlusion post-transplant was small main PV size (P = .008). Post-transplant ultrasonographic warning signs included PV flow <10 cm/sec (P = .003), high hepatic artery flow >70 cm/sec (P = .027), and lesser hepatic artery resistance index <0.65 (P = .013). Both slow PV flow <10 cm/sec and lesser hepatic artery resistance index have high sensitivity and specificity in predicting post-LDLT PVT. CONCLUSION Small PV size (<4 mm) and slow portal flow <10 cm/sec combined with lesser hepatic artery resistance index (<0.65) are strong warning signs that may predict the development of post-LDLT PVT in BA patients that require close monitoring.

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 (>5 mmHg). 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 (>5 mmHg). 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 3.67 years (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.

Doppler Ultrasound Evaluation of Postoperative Portal Vein Stenosis in Adult Living Donor Liver Transplantation

AIM To evaluate the postoperative portal vein stenosis (PVS) and the diagnostic efficiency of Doppler ultrasound (DUS) in adult living donor liver transplantation (ALDLT). MATERIALS AND METHOD From January 2007 to December 2008, 103 ALDLTs were performed and postoperatively followed by routine DUS. The morphologic narrowing at the anastomotic site (AS) of the PVS was analyzed. We calculated the PV stenotic ratio (SR) using the following formula: SR (%)=PRE-AS/PRE (PRE=pre-stenotic caliber). An SR>50% was defined as the critical point for PVS. We also calculated the velocity ratio (VR) between the AS and PRE, and set the significant VR as >3:1. Statistical analyses were carried out to determine clinical significance. RESULTS Using the definition of morphologic PVS by DUS, there were total 20 cases (19.4%) in this series with SR>50%, which included 17 cases with VR>3:1. Eight cases of severe PVS had a stenotic AS>5 mm and subsequently underwent interventional management. Doppler criteria of SR and VR values were elevated up to 75.8% and 7.5:1, respectively, in these treated cases. Two cases of severe PVS subsequently developed PV thrombosis. Intervention by balloon dilation and/or stenting was performed successfully in this PVS case. CONCLUSION DUS is the most convenient and efficient imaging modality to detect and follow postoperative PVS in ALDLT. The Doppler criteria of SR and VR are both sensitive but less specific. Cases of AS<5 mm require interventional management for good long-term graft survival.