This study aims to determine whether intraoperative analysis of arterial and portal venous flow using transit time flow measurement (TTFM) data is associated with a reduced incidence of vascular complications after orthotopic liver transplantation.

This is a retrospective chart review of all adult orthotopic liver transplant recipients at Saint Louis University Hospital from 2015-2020 (n = 188). We reviewed intraoperative flow probe use, as well as documentation of abnormal flow patterns detected during surgery. Normal graft flow measurements were defined as hepatic artery flow >100 ml/min and portal vein flow >0.5 ml/min/gram-liver. Postoperative imaging and ultrasonographic data were then reviewed for reports of vascular complications requiring intervention between the time of transplant and December 31, 2020. The incidence of VCs was compared between those who received intraoperative TTFM and those who did not. We then compared the demographic composition of these 2 groups to ensure similarity and screen for potential confounding factors.

188 liver transplant operative reports met the criteria for inclusion and were reviewed. TTFM use was documented in 78 (41.5%) cases and abnormal flow was detected in 8 (10.3%) of these cases, prompting intraoperative correction. Subsequently, no patients who received intraoperative TTFM developed vascular complications during the postoperative course. Conversely, of the 110 (58.5%) cases with no reported intraoperative flow data, 6 (5.5%, P = .042) patients later developed vascular complications. Reported vascular complications included hepatic artery stenosis, hepatic artery thrombosis, portal vein thrombosis, hepatic vein thrombosis, and IVC thrombosis. There was no significant difference in patient population between patients who received intraoperative TTFM and those who did not, apart from the type of liver implantation. There was a significantly higher prevalence of bicaval liver implantations in the group of patients who did not receive TTFM than those who did (P = .002).

Transit time flow measurement may be a useful tool for the detection of vascular flow abnormalities intraoperatively, allowing for early correction and prevention of vascular complications during the postoperative course. This could potentially result in enhanced graft survival and reduced recipient mortality following orthotopic liver transplantation.

Liver transplantation is the state-of-the-art curative treatment for end-stage liver disease. Imaging is a key element in the detection of intraoperative and postoperative complications. So far, only limited data regarding the best radiological approach to monitor children during liver transplantation is available.

To harmonize the imaging of pediatric liver transplantation, the European Society of Pediatric Radiology Abdominal Taskforce initiated a survey addressing the current status of imaging including the pre-, intra- and postoperative phase. This paper reports the responses related to intraoperative imaging.

An online survey, initiated in 2021, asked European centers performing pediatric liver transplantation 48 questions about their imaging approach. In total, 26 centers were contacted, and 22 institutions from 11 countries returned the survey.

Intraoperative ultrasound (US) is used by all sites to assess the quality of the vascular anastomosis in order to ensure optimal perfusion of the liver transplant. Vessel depiction is commonly achieved using color Doppler (95.3%). Additional US-based techniques are employed by fewer centers (power angio mode, 28.6%; B-flow, 19%; contrast-enhanced US, 14.3%). Most centers prefer a collaborative approach, with surgeons responsible for probe handling, while radiologists operate the US machine (47.6%). Less commonly, the intraoperative US is performed by the surgeon alone (28.6%) or by the radiologist alone (23.8%). Timing of US, imaging frequency, and documentation practices vary among centers.

Intraoperative US is consistently utilized across all sites during pediatric liver transplantation. However, considerable variations were observed in terms of the US setup, technique preferences, timing of controls, and documentation practices. These differences provide valuable insights for future optimization and harmonization studies.

Vascular complications after liver transplant can be lethal. High levels of suspicion and aggressive use of diagnostic tools may help with early diagnosis and treatment. Here, we share our experiences regarding this topic.

Adult and pediatric patients who had liver transplant between February 1997 and June 2018 in our clinic were included in the study. Patients were grouped according to age (pediatric patients were those under 18 years old), male versus female, indication for transplant, type of liver transplant, type of vascular complication, treatment, and survival aftertreatment.We analyzed the statistical incidence of vascular complications according to age, male versus female, and type of liver transplant.

Our analyses included 607 liver transplant procedures, including 7 retransplants, with 349 (57.4%) from living donors and 258 (42.6%) from deceased donors. Of total patients, 539 were adults (89.8%) and 61 were children (10.2%). Vascular complications occurred in 25 patients (4.1%), with hepatic artery complications seen in 13 patients (2.1%) (10 adults [1.8%] and 3 children [4.9%]), portal vein complications seen in 9 patients (1.5%) (6 adults [1.1%] and 3 children [4.9%]), and hepatic vein complications seen in 3 patients (0.5%) (2 adults [0.36%] and 1 child [1.6%]). Rate of vascular complications was statistically higher in pediatric patients (11.4% vs 3.3%; P = .007) and higher but not statistically in recipients of livers from living donors (5.2% vs 2.7%; P = .19). Twelve patients (48.8%) were treated with endovascular approach, and 11 (0.44%)required surgicaltreatment. Two patients underwent immediate retransplant due to hepatic artery thrombosis.

Because vascular complications are the most severe complications afterlivertransplant,there must be close follow-up of vascular anastomoses, particularly early postoperatively, with radiologic methods. In cases of vascular complications, emergent treatment, including endovascular interventions, surgery, and retransplant, must be performed.

This study aimed to find the optimal number of b-values for intravoxel incoherent motion (IVIM) imaging analysis, using simulated and in vivo data from cervical cancer patients.

Simulated data were generated using literature pooled means, which served as reference values for simulations. In vivo data from 100 treatment-naïve cervical cancer patients with IVIM imaging (13 b-values, scan time, 436 seconds) were retrospectively reviewed. A stepwise b-value fitting algorithm calculated optimal thresholds. Feed forward selection determined the optimal subsampled b-value distribution for biexponential IVIM fitting, and simplified IVIM modeling using monoexponential fitting was attempted. IVIM parameters computed using all b-values served as reference values for in vivo data.

In simulations, parameters were accurately estimated with six b-values, or three b-values for simplified IVIM, respectively. In vivo data showed that the optimal threshold was 40 s/mm² for patients with squamous cell carcinoma and a subsampled acquisition of six b-values (scan time, 198 seconds) estimated parameters were not significantly different from reference parameters (individual parameter error rates of less than 5%). In patients with adenocarcinoma, the optimal threshold was 100 s/mm², but an optimal subsample could not be identified. Irrespective of the histological subtype, only three b-values were needed for simplified IVIM, but these parameters did not retain their discriminative ability.

Subsampling of six b-values halved the IVIM scan time without significant losses in accuracy and discriminative ability. Simplified IVIM is possible with only three b-values, at the risk of losing diagnostic information.

To assess the importance of intraoperative portal vein flow measurement during liver transplantation in relation to postoperative complications and graft and patient survival.

Retrospective review including 291 patients who had all the information and covering a period of 10 years (2007-2017). Using a receiver operating characteristic curve, a cut-off point that would have the greatest impact on the probability of being alive at 5 years was established. In relation to this value, 2 groups were formed (low and high flow) and demographic variables, intraoperative variables, postoperative complications, and graft and patient survival were compared.

A portal flow of 123 mL/min per100 g of liver tissue was established (area under the curve = 0.58), obtaining a low-flow (n = 129) and a high-flow group (n = 162). The 2 groups were similar in their preoperative characteristics, except for a higher proportion of preoperative ascites, a higher Model for End-Stage Liver Disease score and a lower weight of donors in the high-flow group. The arterial and portal flows were significantly higher in the high-flow group. In the postoperative period, the high-flow group presented a higher rate of ascites. The 5-year survival rate of patients was significantly higher in the high-flow group (76% vs 84%, P = .03).

Patients undergoing liver transplantation with an intraoperative portal vein flow measurement >123 mL/min per 100 g present a greater 5-year survival rate.

Adequate hepatic arterial (HA) flow to the bile duct is essential in liver transplantation. This study was conducted to determine if the ratio of directly measured HA flow to weight is related to the occurrence of biliary complications after deceased donor liver transplantation.

A retrospective review of 2684 liver transplants carried out over a 25-year period was performed using data sourced from a prospectively maintained database. Rates of biliary complications (biliary leaks, anastomotic and non-anastomotic strictures) were compared between two groups of patients with HA flow by body weight of, respectively, <5 ml/min/kg (n = 884) and ≥5 ml/min/kg (n = 1800).

Patients with a lower ratio of HA flow to weight had higher body weight (92 kg versus 76 kg; P < 0.001) and lower HA flow (350 ml/min versus 550 ml/min; P < 0.001). A lower ratio of HA flow to weight was associated with higher rates of biliary complications at 2 months, 6 months and 12 months (19.8%, 28.2% and 31.9% versus 14.8%, 22.4% and 25.8%, respectively; P < 0.001).

A ratio of HA flow to weight of < 5 ml/min/kg is associated with higher rates of biliary complications. This ratio may be a useful parameter for application in the prevention and early detection of biliary complications.

Vascular complications after liver transplantation increase post-operative morbidity and contribute to the incidence of retransplantation. Vascular complications comprise arterial, caval, and portal venous pathology, with the majority of complications being arterial in etiology, including anastomotic stricture, pseudoaneurysm, and thrombosis. There are two major therapeutic options for the treatment of these arterial complications: endovascular intervention and surgery. The former includes intra-arterial thrombolysis, embolization, percutaneous transluminal angioplasty, and stent placement. The latter includes thrombectomy, reanastomosis, and retransplantation. Although surgical treatment has been considered the first choice for management in the past, advances in endovascular intervention have increased and make it a viable therapeutic option following orthotopic liver transplantation. This review focuses on the role of surgical and endovascular therapy in the management of hepatic arterial complications after liver transplantation.

Hepatic artery thrombosis (HAT) represents the most common vascular complication occurring after liver transplantation (LT). Herein, we report the results of a prospective study of hepatic artery flow (HAF) measurement during abdominal wall closure after LT along with the results of an international survey of procedures adopted, in order to avoid the arterial kinking (AK) in case of long artery.

Sixty-four surgeons were asked regarding the different procedures used to avoid AK in the presence of long artery. We prospectively assessed the HAF during three phases of LT in 26 consecutive LT performed in patients with a long HA: after completion of the biliary anastomosis (M0), and partial abdominal wall closure with (M1w) or without (M1w/o) hepatic artery anti-kinking method (HAAK).

Sixty (93.7 %) surgeons replied to the survey: 44 (73.3 %) surgeons cut the artery as short as possible, of whom 38 (86.3 %) interposed an oxidized polymer or the omentum, and six (13.7 %) used other systems. Fourteen (23.3 %) surgeons did not use any interposition methods. The remaining two (3.3 %) surgeons left a long artery without HAAK. In our cohort we obtained the following HAF measures: M0 152 mL/min (89-205), M1 without HAAK 114 (66-168) and M1 with HAAK procedure 158 (91-219) (p = 0.002).

Our survey confirms that no consensus is currently available regarding the most effective method for avoiding AK. Kinking occurs most probably when the liver is released in its final position. The utilization of an interposition method could ensure the maintenance of a correct HAF.

Splenic artery "steal" syndrome after orthotopic liver transplantation (OLT) is an important cause of graft dysfunction. Direct pressure measurement in the hepatic (HA) and radial artery (RA) may identify patients at risk allowing its prevention. This observational study compared radial and hepatic mean arterial pressures (MAP) measured during 100 OLTs performed in 99 recipients, in whom the HA was considered suitable for the anastomosis. A difference of ≥5 mmHg between the radial and hepatic MAP was arbitrarily chosen as the criterion for inflow modulation. Seven patients fulfilled this criterion showing a MAP gradient that was significantly different compared to the others (-10.8±3.3 vs. 2.6±5.0; p<0.0001). They underwent splenic artery ligation (n=5), arcuate ligament division (n=1) and aortohepatic bypass grafting (n=1) that all resulted in immediate normalization of the arterial inflow pressure to the graft. The splenic artery "steal" syndrome occurred in one patient (day 2 after OLT) in whom the mean HA pressure normalized during OLT following arcuate ligament division, suggesting pathology within the graft as the most likely etiology. Our results indicate that radial MAP can reflect the hepatic MAP during OLT. If a substantial pressure gradient is found, it can be corrected by intraoperative splenic artery ligation or arcuate ligament division.

Proper liver perfusion is essential for sufficient organ function after liver transplantation. The aim of this study was to determine the effects of portal and arterial blood flow on liver function and organ survival after liver transplantation. The arterial and portal venous blood flow was measured intraoperatively by transit time flow measurement after reperfusion for 290 consecutive liver transplants. The graft survival, hepatic cell damage (alanine aminotransferase and aspartate aminotransferase), and liver function (prothrombin ratio and bilirubin) were determined. Grafts were stratified into groups according to arterial blood flow measurements [<100 mL/minute for arterial blood flow group I (ART I), 100-240 mL/minute for ART II, and ≥ 240 mL/minute for ART III] and portal venous blood flow measurements (<1300 mL/minute for portal venous blood flow group I and ≥ 1300 mL/minute for portal venous blood flow group II). With multivariate analysis, the impact of blood flow on graft survival was determined, and potential confounders were considered. Decreased portal venous blood flow was associated with significantly less organ survival in univariate analysis but not in multivariate analysis. In contrast, the arterial blood flow was significantly correlated with organ survival after liver transplantation in univariate and multivariate analyses [hazard rate ratio = 2.5, confidence interval = 1.6-4.1, P < 0.001, median survival = 56.6 (ART I), 82.7 (ART II), or 100.7 months (ART III)]. Moreover, low arterial blood flow resulted in impaired postoperative organ function and higher rates of primary nonfunction. Biliary complications were not affected by blood flow. Other risk factors for graft failure that were identified by multivariate analysis included retransplantation, histidine tryptophan ketoglutarate solution versus University of Wisconsin solution, and donor treatment with epinephrine. Impaired arterial blood flow after reperfusion represents a significant predictor of primary graft nonfunction and is associated with impaired graft survival. Whether the intraoperative measurement of hepatic arterial flow is predictive of graft survival should be evaluated in a prospective trial.

We hypothesized that operative variables might predict survival following liver transplantation.

We examined perioperative variables from 469 liver transplants carried out at the University of Washington during 2003-2006. Logistic regression determined the variables' contributions to survival at 30, 90 and 365 days.

Portal vein blood flow (>1 l/min) was significant to patient survival at 30, 90 and 365 days. Complete reperfusion was only a significant predictor of survival at 30 days. This provided model receiver operating characteristic (ROC) area under the curve (AUC) statistics of 0.93 and 0.87 for 30 and 90 days, respectively. At 365 days, hepatic artery blood flow (>250 ml/min) combined with portal vein blood flow was significantly predictive of survival, with an AUC of 0.74. A subset analysis of 110 transplants demonstrated improved 1-year survival with more aggressive vascular revisions.

Portal vein blood flow is a significant predictor of survival after liver transplantation. Initially, the liver's survival is based on portal vein blood flow; however, subsequent biliary problems and patient demise result from both poor portal vein and inadequate hepatic artery blood flow.

Arterial problems remain a formidable challenge in liver transplantation. In many situations, an aortohepatic conduit can provide a solution. No long-term results (over 5 years) have been reported. This study was designed to assess the impact of aortohepatic conduits on graft survival after liver transplantation and the safety of aortohepatic conduits and to establish the long-term results (up to 20 years) of aortohepatic conduits. Data from 2346 adult liver transplants were prospectively collected into the computerized database and analyzed. In the majority of cases, arterial conduits were constructed from the donor iliac artery obtained at the liver retrieval. Aortohepatic conduits were required in 149 (6.4%) first transplants. The long-term graft survival after liver transplantation using aortohepatic conduits was excellent and comparable to that of the control group. The graft survival was 59% with the conduit versus 67% without the conduit at 5 years of follow-up, 50% versus 52% at 10 years, and 33% versus 35% at 15 years. With up to 20 years of follow-up, there was no statistically significant difference in graft survival, patient survival, hepatic artery complications, or biliary complications. For the same time period, there was no statistically significant difference in graft survival or patient survival for the retransplants with and without aortohepatic conduits. In conclusion, in experienced hands, aortohepatic conduits can be used safely for liver transplantation with no negative impact on long-term graft survival, patient survival, hepatic artery complications, or biliary complications. Excellent long-term results can be obtained.

A reliable method to recognize the extent of ischemia/reperfusion injury in transplantation is needed in order to tailor the immunosuppressive scheme to the needs of a damaged organ. This study sought to assess the correlation between the total and the parenchymal blood flow into a transplanted kidney (n = 71) or liver (n = 15) shortly after revascularization with the early function of the organ after transplantation. The total blood flow in the renal artery in kidney recipients or in the hepatic artery and portal vein in liver recipients was measured by an electromagnetic flowmeter. The parenchymal blood flow (in several parts of the transplanted organ) was assessed using a laser-Doppler flowmeter. Two measurements were always taken after revascularization (5 to 60 minutes apart). Vascular resistance (VR) as calculated by the difference between the mean arterial pressure (MAP) and the central venous pressure (CVP) was correlated with immediate kidney or liver function parameters. Neither total renal blood flow (RBF) nor VR was different between the immediate function (IF) and delayed graft function (DGF) groups of kidney transplant patients. However, the cortical (parenchymal) blood flow was significantly greater in the IF than the DGF group at 5 minutes: 29.98 +/- 6.13 mL/min/100 g vs 23.56 +/- 6.46 mL/min/100 g (P < .001). The difference was even more significant at 35 minutes: 33.94 +/- 7.47 mL/min/100 g vs 15.47 +/- 3.34 mL/min/100 g (P < .0001). Among liver transplant patients, the results suggested a correlation between hepatic arterial blood flow and early graft viability and function. The most reliable predictor of early graft function was the portal blood flow, which correlated with the volume of secreted bile as well as the bilirubin, and transaminase levels and coagulation profile. Further studies must confirm the value of measurements of total and parenchymal blood flow in organ transplant recipients.

Our previous studies showed a correlation of intraoperative renal allograft blood flow and immediate functions. A similar relation is not well established for liver transplantation. The aim of this study was to assess the relation between hepatic blood flow on revascularization and immediate liver graft function (IF).

Studies evaluating arterial and portal flow in newly transplanted livers were started in May 2004. Total hepatic artery and portal vein blood flow were assessed in 15 liver transplant recipients. Parenchymal flow was also recorded. Measurements were taken at 30 and 120 minutes after simultaneous arterial/portal reperfusion. Flow results were correlated with IF.

Mean arterial blood flow (ABF) was 16.3 mL/min/100 g in both measurements. Portal flow was reduced from 168 to 127 mL/min/100 g from the first to the second measurement. Mean parenchymal flow (PF) did not alter over time (29.1 and 30.4 mL/min/100 g, respectively). Among recorded flow results we observed a significant correlation between PF with IF measured as: bile volume (R = 0.36 to 0.62; P < .05), serum AST (R = -0.4 to -0.68; P < .05), and ALT level (R = -0.2 to -0.71; P < .05), bilirubin level as well as INR (R = -0.39 to -0.61; P < .05) assayed daily for 14 days. Similar observations were made between ABF and INR, hiatal parenchymal flow, and ALT as well as INR.

These preliminary results suggest hepatic blood flow may be a reliable predictor of graft viability and function. Of the variables measured, portal blood flow seems to be the most valuable indicator of liver function.

Hyperbilirubinemia, a common complication associated with left ventricular assist device (LVAD) implantation, is evidence of liver dysfunction and is often a life-threatening problem after the implantation procedure. In this study we evaluated the relationship between hemodynamics after LVAD implantation and postoperative hyperbilirubinemia. Twenty-four patients who received LVADs at Osaka University Hospital between January 1994 and June 2002 were retrospectively reviewed. Patients were grouped according to the implanted LVAD: Group A (n = 4) Novacor, group B (n = 7) HeartMate 1000IP, group C (n = 13) Toyobo pneumatic pulsatile pump. Hemodynamic data and laboratory data, including total bilirubin on postoperative days (PODs) 1, 3, 7, and 14, were collected and statistically analyzed. In group C, the cardiac index (CI) on POD 1 was significantly lower (P < 0.01) than that for groups A and B. On PODs 3 and 7, total bilirubin levels in group C increased significantly over the preoperative value (P < 0.05) and were significantly higher than those in group A on POD 3 and higher than those in groups A and B on POD 7 (P < 0.05). Regression analysis of CI on POD 1 correlated significantly with total bilirubin on POD 7, as expressed by the formula y = 5.13/(x - 1.7)(0.719), where x is CI and y is total bilirubin (r(2) = 0.327, P < 0.05). Total bilirubin after LVAD implantation correlates with postoperative CI values. We suggest that it is essential to maintain the CI at the highest levels possible to avoid postoperative hyperbilirubinemia in LVAD patients.