LIVER TRANSPLANTATION 21:321–328, 2015
ORIGINAL ARTICLE
Thrombolytic Protocol Minimizes Ischemic-Type Biliary Complications in Liver Transplantation From Donation After Circulatory Death Donors John B. Seal,1 Humberto Bohorquez,2 Trevor Reichman,2 Adam Kressel,2 Anand Ghanekar,1 Ari Cohen,2 Ian D. McGilvray,1 Mark S. Cattral,1 David Bruce,2 Paul Greig,1 Ian Carmody,2 David Grant,1 Markus Selzner,1 and George Loss2 1 Multi-Organ Transplant Program, Department of Surgery, Toronto General Hospital, University of Toronto, Toronto, Canada; and 2Multi-Organ Transplant Institute, Ochsner Clinic Foundation, New Orleans, LA
Liver transplantation (LT) with donation after circulatory death (DCD) donors has been associated with a high rate of ischemic-type biliary strictures (ITBSs) and inferior graft survival. To investigate the impact of an intraoperative tissue plasminogen activator (tPA) on outcomes following DCD LT, we conducted a retrospective analysis of DCD LT at the Toronto General Hospital (TGH) and the Ochsner Medical Center (OMC). Between 2009 and 2013, 85 DCD LTs were performed with an intraoperative tPA injection (n 5 30 at TGH, n 5 55 at OMC), and they were compared with 33 DCD LTs without a tPA. Donor and recipient characteristics were similar in the 2 groups. There was no significant difference in the intraoperative packed red blood cell transfusion requirement (3.2 6 3.4 versus 3.1 6 2.3 U, P 5 0.74). Overall, biliary strictures occurred less commonly in the tPA-treated group (16.5% versus 33.3%, P 5 0.07) with a much lower rate of diffuse intrahepatic strictures (3.5% versus 21.2%, P 5 0.005). After 1 and 3 years, the tPA group versus the non-tPA group had superior patient survival (97.6% versus 87.0% and 92.7% versus 79.7%, P 5 0.016) and graft survival (96.4% versus 69.7% and 90.2% versus 63.6%, P < 0.001). In conclusion, a tPA injection into the hepatic artery during DCD LT reduces ITBSs and improves graft and patient survival without increasing the risk for bleeding. Liver Transpl 21:321-328, 2015. C 2015 AASLD. V Received June 3, 2014; accepted November 17, 2014. The use of liver transplantation (LT) as a lifesaving treatment for patients with end-stage liver disease continues to be primarily limited by donor organ availability. Donation after circulatory death (DCD) donors represent an important potential source to expand the donor pool for LT. However, posttransplant outcomes following DCD LT have to date been inferior in comparison with outcomes following LT
with donation after brain death (DBD) donors.1-8 Despite an increased use of DCD livers in the early part of the past decade, utilization has decreased in recent years as a result of inferior outcomes.9 Biliary complications are the main contributor to inferior outcomes in DCD LT, with reported biliary stricture rates between 30% and 50% (more than double the rate for LT from DBD donors). The higher rate
Abbreviations: ALP, alkaline phosphatase; AST, aspartate aminotransferase; BMI, body mass index; DBD, donation after brain death; DCD, donation after circulatory death; FFP, fresh frozen plasma; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; HTK, histidine tryptophan ketoglutarate; ICU, intensive care unit; INR, international normalized ratio; ITBS, ischemic-type biliary stricture; LT, liver transplantation; MELD, Model for End-Stage Liver Disease; OMC, Ochsner Medical Center; PRBC, packed red blood cell; PTC, percutaneous transhepatic cholangiography; SPS, static preservative solution; TGH, Toronto General Hospital; tPA, tissue plasminogen activator; UW, University of Wisconsin. The author contributions were as follows: David Grant, Trevor Reichman, Markus Selzner, and George Loss participated in the research design; John B. Seal, Trevor Reichman, Markus Selzner, George Loss participated in the writing of the article; John B. Seal, Adam Kressel, Anand Ghanekar, Ari Cohen, Ian D. McGilvray, Humberto Bohorquez, Mark S. Cattral, David Bruce, Paul Greig, Ian Carmody, David Grant, Trevor Reichman, Markus Selzner, and George Loss participated in the performance of the research; and John B. Seal, Trevor Reichman, Markus Selzner, and George Loss participated in data analysis. Address reprint requests to Markus Selzner, Multi-Organ Transplant Program, Department of Surgery, Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada. E-mail: [email protected] DOI 10.1002/lt.24071 View this article online at wileyonlinelibrary.com. LIVER TRANSPLANTATION.DOI 10.1002/lt. Published on behalf of the American Association for the Study of Liver Diseases
C 2015 American Association for the Study of Liver Diseases. V
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of biliary strictures in DCD LT is likely a result of ischemic-type biliary strictures (ITBSs), which occur in both focal and diffuse patterns. These strictures are often progressive in nature, are refractory to endoscopic/radiologic interventions, and often progress to cholestatic liver failure and require retransplantation. Although the exact pathophysiology of ITBSs is unknown, it has been hypothesized that the formation of microthrombi in the peribiliary circulation, either during the acirculatory phase of DCD withdrawal or in the early reperfusion period, leads to bile duct ischemia, inflammation, and fibrosis. On the basis of this premise, Hashimoto et al.10 hypothesized that the administration of a tissue plasminogen activator (tPA), a potent thrombolytic agent, into the hepatic artery before reperfusion would dissolve thrombi in the microcirculation and ameliorate the formation of ITBSs. Results from a pilot series of 22 patients were promising, and many centers in North America have adopted tPA administration in institutional protocols for DCD LT. However, the use of tPA in LT, especially in coagulopathic patients with liver disease, raises concern about the risk of bleeding, which is unknown in this clinical application. Following the report by Hashimoto et al.,10 Toronto General Hospital (TGH; Toronto, Ontario, Canada) and the Ochsner Medical Center (OMC; New Orleans, LA), independently adopted similar tPA protocols for DCD LT in 2009 in an effort to improve outcomes. The aims of this study were to determine the effects of tPA on biliary complications, graft survival, and patient survival following DCD LT and to assess the risk of bleeding after tPA administration into the graft.
PATIENTS AND METHODS Study Design DCD LTs performed at OMC and TGH from April 2006 through August 2013 were retrospectively reviewed from a transplant database at each institution as well as patient chart reviews. A protocol for the use of tPA infusion into the hepatic artery around the time of portal vein reperfusion was introduced in April 2009 at TGH and in October 2009 at OMC. After the introduction of the protocols, tPA was routinely used for DCD LT with the exception of 2 patients at TGH to whom tPA was not given at the discretion of the operating surgeon because of a concern about bleeding risk. The study was approved by the research ethics board at TGH and the institutional review board at OMC.
Organ Procurement and LT Technique The allocation of organs from DCD donors was coordinated by the Trillium Gift of Life Network for TGH and the regional organ procurement organization for OMC. Recipient allocation was based on the calculated sodium Model for End-Stage Liver Disease (MELD) score with the exception of patients listed for hepatocellular carcinoma (HCC), who received exception
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points per the standard protocol at the time. The identification of potential DCD donors, the process of withdrawal of life support, and the declaration of donor death were completed by an intensive care physician at the donor hospital and were completely independent of the recovery and recipient teams. Donor withdrawal was performed in the setting of the intensive care unit (ICU) or in an operating room separate from the recovery team. Donor vitals during the withdrawal process were recorded and communicated to the recovery team until circulatory arrest. The start of the donor warm ischemia time was defined by the time of extubation at TGH and by oxygen saturation < 80% or a systolic blood pressure < 80 mm Hg at OMC. A cutoff of 30 minutes from the start of warm ischemia to the start of the in situ flush was used for organ acceptance at both centers. For the purpose of analysis, the TGH definition of donor warm ischemia time was used for both groups. Because of the difference in the definitions of the start of warm ischemia, warm ischemia times for OMC were longer when they were measured from the point of extubation. For DCD donors accepted by TGH, heparin was routinely given at the time of extubation at a dose of 1000 U/kg or at a reduced dose of 500 U/kg in the context of intracranial hemorrhage. In contrast, for DCD donors accepted by OMC, a reduced dose of heparin (typically 2000-3000 U) was given. In Ontario, withdrawal of life support in the donor occurred most often in the ICU or recovery room of the operating room and thus required additional transport time during warm ischemia. Withdrawal for most DCD donors accepted by OMC was carried out in the operating room. After determination of circulatory arrest, a mandatory 5- to 10-minute “hands-off” period was observed before the final declaration of death; this depended on the local hospital policy. The recovery procedure was performed by experienced surgeons and emphasized rapid abdominal exposure, aortic/iliac artery cannulation, and systemic perfusion with a hypothermic static preservative solution (SPS) or University of Wisconsin (UW) solution. The bile duct was transected and flushed in situ, and a second portal venous, arterial, and biliary flush was performed immediately after graft removal on the back table. At OMC, a retrograde hepatic vein flush was also performed on the back table. For the recipient transplant procedure, a caval replacement technique was used with the exception of 4 cases, for which a bicaval piggyback technique was used. Biliary reconstruction was performed from duct to duct in all cases with the exception of 7 Roux-en-Y enteric drainage cases, which were performed at TGH.
tPA Dosing and Administration Thrombolytic protocols independently adopted at OMC and TGH were similar with the exception of the dosage and timing of tPA administration (Table 1 and Fig. 1). At both centers, tPA was reconstituted at room temperature with sterile water at a concentration of
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TABLE 1. DCD LT Thrombolytic Protocols
Donor age limit Heparin dose (antemortem) Start of warm ischemia
Warm ischemia limit Flush solution Organ recovery technique Back-table flush tPA dosing tPA administration
OMC
TGH
60 years 30,000 U Systolic blood pressure < 80 mm Hg or saturation < 80% 30 minutes UW/HTK Standard Yes 2 mg 1 5 mg of verapamil Before hepatic artery anastomosis
55 years 1000 U/kg of donor weight Extubation
Figure 1. Timing of tPA administration. OMC and TGH independently adopted thrombolytic protocols for the use of tPA in DCD LT with differences in the timing of tPA administration.
1 mg/mL. At TGH, the tPA dose was based on the donor’s weight (100 mg/kg) to account for variations in the graft size. The median volume of administered tPA was 7 mL (range 5 4-10 mL). Before completion of the portal vein anastomosis, tPA was administered. With the liver graft in situ after upper and lower caval anastomoses, the portal vein anastomosis was set up, and the corner sutures were placed. Recombinant tPA (Alteplase, Hoffmann-La Roche, Mississauga, Canada) was then administered into the hepatic artery above the level of the gastroduodenal artery stump to maximize the distribution to the intrahepatic vasculature. A microvascular clamp was placed on the hepatic artery to prevent backflow. The portal vein anastomosis was then completed (approximately 5-10 minutes), and the liver was flushed with 200 to 300 mL of portal venous flow vented through a chest tube in the lower caval anastomosis. The hepatic artery anastomosis was then performed, and this completed the vascular reperfusion of the graft. The original report by Hashimoto et al.10 described the administration of tPA into the hepatic artery during the back-table preparations. The TGH protocol was modified to administer the tPA closer to the time of the portal reperfusion to limit the effects of hypothermia and dilution. At OMC, the liver graft was routinely flushed in situ with hypothermic 5% albumin during the upper and lower caval anastomoses, and this eliminated the need for a portal blood flush before reperfusion. After completion of the portal vein anastomosis and the restoration of the portal perfusion, 5 mg (5 mL) of
30 minutes UW/SPS En bloc liver/pancreas Yes 100 mg/kg of donor weight Before portal vein anastomosis (5-10 minutes before portal reperfusion)
verapamil was introduced as a vasodilator directly into the hepatic artery, and this was immediately followed by a fixed dose of 2 mg (2 mL) of tPA (Alteplase, Genentech, San Francisco, CA). A microvascular clamp was placed above the level of the gastroduodenal stump to prevent backflow. The arterial anastomosis was completed, and the arterial perfusion of the graft was restored. No formal back-bleeding procedure was performed.
Posttransplant Outcomes Graft function and acute reperfusion injury were assessed in the early postoperative period (48 hours) by peak serum aspartate aminotransferase (AST). Short-term graft function was assessed by total serum bilirubin, alkaline phosphatase (ALP), and the international normalized ratio (INR) 6 and 12 months after the transplant. Graft failure was determined by the time of listing for retransplantation or patient death. Biliary complications were identified by abnormal liver function tests or a clinical presentation consistent with cholangitis and were diagnosed by cholangiography. Categorization of biliary strictures was based on the interpretation of imaging from percutaneous transhepatic cholangiography (PTC), endoscopic retrograde cholangiography, or magnetic resonance cholangiopancreatography. For the purposes of analysis, biliary strictures were classified as diffuse intrahepatic strictures or focal extrahepatic strictures. Diffuse intrahepatic strictures were not amenable to definitive management with endoscopic or radiographic stenting, and more often, they progressed to graft failure. Anastomotic strictures and focal ischemic-type strictures in the extrahepatic biliary tree were often difficult to delineate on cholangiography and thus were grouped together for the purposes of analysis. All of these strictures were successfully managed with endoscopic or percutaneous dilation and stenting with the exception of one that was corrected with conversion to Roux-en-Y enteric biliary drainage.
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TABLE 2. Donor and Recipient Characteristics
Recipient Age (years) Sex (male) BMI (kg/m2) Diagnosis HCV HCC MELD Donor Age (years) Sex (male) BMI (kg/m2) Cause of death Trauma Anoxia Cerebrovascular accident Warm ischemia time (minutes) Cold ischemia time (hours) Regional share National share
tPA (n 5 85)
No tPA (n 5 33)
P
54.6 6 10.9 57 (67.1%) 24.7 6 10.5
53.2 6 10.6 24 (72.7%) 27.4 6 4.9
0.55 0.66 0.56
43 (50.6%) 32 (37.6%) 20.1 6 8.2
18 (54.5%) 8 (24.2%) 16.5 6 10.8
0.84 0.19 0.38
36.3 6 14.8 51 (60.0%) 26.8 6 6.0
38.0 6 14.9 11 (33.3%) 27.1 6 7.6
0.99 0.01 0.05
15 (17.6%) 38 (44.7%) 24 (28.2%) 21.1 6 8.3 5.1 6 1.2 30 (35.3%) 1 (1.2%)
6 (18.2%) 11 (33.3%) 11 (33.3%) 23.5 6 7.6 4.3 6 1.0 2 (6.1%) 0
1 0.3 0.65 0.16 0.004 0.001 1.0
TABLE 3. Intraoperative Blood Product Usage
PRBCs (U) FFP (U) Platelets (U) Autologous red blood cells (mL)
tPA (n 5 85)
No tPA (n 5 33)
P
3.2 6 3.4 (0-24) 5.9 6 4.3 9.5 6 1.9 462.4 6 618.0
3.1 6 2.3 (0-8) 7.9 6 4.0 4.2 6 4.8 060
0.74 0.25 0.03 0.41
Statistical Analysis Statistical analysis was performed with XLSTAT software version 8.0 (XLSTAT for Windows Excel, New York, NY), and GraphPad Prism 5.04 for Windows (GraphPad Software, La Jolla, CA). Fisher’s exact test was used for categorical variables, whereas a Student t test was performed for continuous parametric variables, and a Mann-Whitney U test was used for nonparametric continuous variables. Graft survival and patient survival were calculated with the KaplanMeier survival analysis and were compared with the log-rank test. P 0.05 was considered statistically significant.
at the time of transplant, or the diagnosis of hepatitis C virus (HCV) or HCC. A higher percentage of donors were male in the tPA group (60.0% versus 34.4%, P 5 0.01), but otherwise, there was no difference in donor age, body mass index (BMI), or cause of death. The cold ischemia time was significantly longer in the tPA group (5.1 6 1.2 versus 4.3 6 1.0 hours, P 5 0.004). There was no significant difference in donor warm ischemia times (extubation to in situ cold perfusion) between the tPA group and the untreated group (21.1 6 8.3 versus 23.5 6 7.6 minutes). Regional-share donors were used more frequently in the tPA group (35.3% versus 6.1%, P 5 0.001), and a national-share donor was used in only 1 patient in the tPA group.
RESULTS Donor and Recipient Characteristics
Intraoperative Bleeding
During the study period, 118 DCD LTs were performed in all at OMC and TGH. Among these DCD LT cases, 85 received tPA, and 33 did not. Donor and recipient characteristics for each group are presented in Table 2. There was no difference between the 2 groups with respect to recipient age, the MELD score
Intraoperative administration of blood products was compared to determine the effects of tPA on the risk of bleeding (Table 3). There was no difference in the mean number of units of packed red blood cells (PRBCs), fresh frozen plasma (FFP), or volume of autologous red blood cells infused for the 2 groups
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TABLE 4. Posttransplant Outcomes
Mean follow-up (months) Length of hospitalization (median number of days, range) Peak AST at 48 hours (U/L) AST at 7 days Total bilirubin (mg/dL) 7 days 6 months 12 months ALP (U/L) 6 months 12 months INR at 12 months Retransplant
No tPA (n 5 33)
Ochsner tPA (n 5 56)
P
Toronto tPA (n 5 29)
P
73.7 6 16.9 12 (5-162)
32.4 6 12.1 8 (4-95)
0.001 0.03
39.4 6 15.5 10 (4-118)
0.001 0.03
1792.1 6 1720.5 605.2 6 1018.7
2241.7 6 1995.1 56.3 6 36.2
0.28 0.001
1852.0 6 1817.7 63.8 6 84.1
0.89 0.006
4.2 6 3.3 4.7 6 7.2 3.5 6 6.8
2.7 6 3.2 1.4 6 2.5 0.8 6 0.7
0.04 0.002 0.004
3.3 6 2.9 0.8 6 0.5 1.8 6 4.4
0.26 0.005 0.25
235.0 6 189.8 285.4 6 521.9 1.1 6 0.2 6 (18.2%)
156.9 6 133.3 144.5 6 107.7 1.2 6 0.5 2 (3.6%)
0.03 0.05 0.28 0.05
191.5 6 150.0 178.0 6 140.6 1.2 6 0.2 0 (0%)
0.32 0.15 0.05 0.03
(Table 3). The mean number of units of platelets was higher in the tPA-treated group (9.5 6 1.9 versus 4.2 6 4.8 U, P 5 0.03). The proportion of cases using 5 U of PRBCs was not higher for the tPA group versus the untreated group (14.1% versus 12.1%, P 5 0.63).
Posttransplant Outcomes A tPA protocol for DCD LT was introduced in January 2009 in Toronto and in October 2009 for OMC. The mean follow-up was longer for the untreated group (64.2 6 14.4 versus 22.5 6 13.7 months, P < 0.001). After implementation of the protocol, tPA was not administered in 2 cases at the discretion of the operating surgeon, and they were included in the untreated group for analysis. The mean lengths of hospitalization and ICU stays were shorter in the tPA group, although the difference was not significant (Table 4). There was no significant difference in peak posttransplant serum AST (2174.5 6 1922.1 versus 1792.1 6 1720.5 U/L, P 5 0.2). The mean total serum bilirubin was significantly higher in the untreated group 6 and 12 months after the transplant. Similarly, the mean ALP was also higher in the untreated group 6 and 12 months after the transplant (Table 4). Synthetic function was assessed by a measurement of the INR 12 months after the transplant and was normal for the tPA and untreated groups (1.19 6 0.68 versus 1.07 6 0.2, P 5 0.87). The mean serum creatinine after transplantation for both groups was 1.28 mg/dL at 48 hours and 1.21 mg/dL at 7 days.
Biliary Complications The overall rate of biliary complications in the tPA group was 16.5% versus 33.3% in the control group. Biliary complications were classified as diffuse intrahepatic or focal extrahepatic. Diffuse strictures were not definitively managed with endoscopic or radiographic dilation and stenting, and they more often progressed to prolonged biliary complications and graft failure. Focal strictures, including anastomotic
strictures, occurred in the extrahepatic biliary system and were amenable to dilation and stenting interventions with the exception of 1 case in the tPA-treated group that required surgical revision to the Roux-en-Y biliary enteric drainage. Although some focal strictures required multiple interventions, none led to refractory biliary complications and graft failure. Because the tPA protocol adopted at each center was different, biliary complications were reported separately. There was no significant difference in the rate of focal extrahepatic strictures in the untreated group (12.1%) and the tPA group at OMC (16.1%, P 5 0.75) and TGH (10.3%, P 5 0.99; Fig. 2). However, the rate of diffuse intrahepatic strictures was significantly lower in the tPA group at OMC (3.6%) and TGH (0%) versus the untreated group (21.2%, P 5 0.005). Two patients in the tPA group developed delayed hepatic artery thrombosis (at postoperative days 38 and 114) and subsequent biliary complications leading to graft loss and retransplantation. One patient in the tPA group developed a focal stricture near the level of the hepatic duct confluence, which required surgical revision of the biliary anastomosis after failure of the PTC drainage and stent.
Patient and Graft Survival Overall, graft survival was higher in the tPA group versus the untreated group at 1 year (96.4% versus 69.7%) and 3 years (90.2% versus 63.6%, P < 0.001) after transplantation. Patient survival after the transplant was also significantly higher in the tPA group versus the untreated group at 1 year (97.6% versus 87.0%) and 3 years (92.7% versus 79.7%, P 5 0.016) after transplant (Fig. 3). There were no significant differences between the TGH and OMC tPA groups in overall patient survival (95.5% versus 98.1%, P 5 0.70) or graft survival (95.5% versus 96.1%, P 5 0.39), respectively. The recipient rate of death from sepsis related to biliary complications was significantly higher in the
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Figure 2. Biliary stricture formation following DCD LT. The overall rate of biliary strictures was lower among DCD LT patients treated with tPA in the hepatic artery near the time of graft reperfusion. There was no significant difference in the rates of focal strictures, but there was a significantly lower rate of diffuse intrahepatic strictures in the tPA-treated groups (3.5% versus 21.2%, P 5 0.005). There were no diffuse intrahepatic biliary strictures in the tPA-treated group at TGH. *3.5% versus 21.2%, P < 0.005.
untreated group (n 5 3) versus the tPA-treated group (n 5 0, P 5 0.02). Two patients in the untreated group and 1 in the tPA group died from sepsis unrelated to biliary complications. There were 2 deaths secondary to cardiopulmonary events in each group. One patient in the tPA group died of an intraoperative pulmonary embolism, and 1 died from graft-versus-host disease. In the untreated group, 4 of the 8 patients with HCC died of tumor recurrence versus only 2 of the 32 HCC patients in the tPA group. Both groups were similar with respect to the tumor stage at the time of transplantation.
DISCUSSION The utilization of livers from DCD donors has been limited by inferior outcomes due in large part to biliary complications. Several measures have been proposed to reduce the incidence of ITBSs in DCD LT: avoiding older or unstable donors, expediting organ retrieval to limit donor warm ischemia time, using in situ biliary and back-table vascular flushing, and limiting the cold ischemia time and simultaneous arterial and portal revascularization.5,11-15 Despite widespread application of many of these strategies, outcomes from DCD LT remain inferior to those from LT using DBD donors. Hashimoto et al.10 first described the use of tPA as a novel clinical strategy to improve peribiliary microcirculation and reduce the incidence of ITBSs in LT. In our review of the use of tPA in DCD LT at 2 high-volume LT centers in North America, we demonstrate a significant reduction of diffuse ITBSs and improved patient and graft survival in comparison with DCD LT without tPA. Overall, we observed a lower rate of biliary complications in the tPA group in comparison with the
Figure 3. Patient and graft survival following DCD LT. Overall patient survival (top) and graft survival (bottom) were higher for DCD LT patients treated with tPA 1 and 3 years after the transplant.
untreated DCD LT group. Although we did not observe a difference in the rate of focal strictures, the rate of diffuse strictures was significantly lower in the tPA group at both centers. Furthermore, in the tPA group, diffuse strictures were seen exclusively in the setting of delayed hepatic artery thrombosis. The difference in the rate of diffuse intrahepatic strictures is clinically significant because diffuse strictures are least amenable to stenting and drainage and often progress to graft failure and retransplantation. The reduction in diffuse intrahepatic strictures supports the hypothesis that tPA clearance of peribiliary microthrombi reduces ischemic events that can lead to stricture formation throughout the liver. In keeping with this finding, we also observed a lower rate of graft loss in the tPA-treated group versus the controls. Tissue plasminogen activator is naturally produced by the liver and acts in the fibrinolytic pathway by converting plasminogen to the active form of plasmin. Plasminogen is ubiquitous in circulation and tissue
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and can form a local reservoir by binding to the surface of a clot to target the fibrinolytic effect.16,17 Although the precise pharmacokinetics of tPA are unknown in this application, it is likely to have reduced activity in hypothermic conditions and with a low substrate (plasminogen) concentration in the preserved graft. We speculate that a majority of the fibrinolytic activity occurs upon portal vein reperfusion with a return to normothermic conditions and an ample supply of plasminogen. The use of a fibrinolytic agent in LT and especially in the setting of coagulopathy of liver disease raises concern about a bleeding risk. In their original report, Hashimoto et al.10 reported excessive bleeding in 64% of patients receiving tPA. However, this was not a dose-dependent risk and was likely confounded by reperfusion effects related to graft quality. In our combined experience, we did not observe any significant increase in intraoperative bleeding associated with the use of tPA. One outlier case in the tPA group required 24 U of PRBCs intraoperatively, but most transfusions occurred before reperfusion during the recipient hepatectomy because of coagulopathy, varices, and prior abdominal surgery. Approximately 25% of the patients in the tPA group did not require any PRBC transfusion, and this suggests that if there is a real increased risk of bleeding, it is not uniform and likely depends on other factors such as reperfusion effects, underlying coagulopathies, and higher risk hepatectomies. Under normal conditions, tPA is rapidly cleared by the liver with a systemic half-life of 5 minutes. Therefore, it is unlikely to have significant systemic effects in this application. The primary limitation of this study is the retrospective design. Although data were prospectively collected in a transplant research database, there was no randomization of tPA therapy. DCD LTs performed without tPA occurred early in each center’s experience with DCD LT. Thus, the improved outcomes that we observed in the tPA treatment group may be confounded by center experience with DCD LT. However, we did not observe significant differences in donor or recipient characteristics or donor warm ischemia times, factors more likely to be affected by refinement of the organ recovery process and patient selection. Furthermore, the cold ischemia time was significantly longer and the regional share was significantly higher in the tPA-treated group, and this suggests a less conservative approach when a center has more experience. Despite efforts to carefully select donors and minimize cold and warm ischemia times, our initial experience with DCD LT at both centers yielded inferior graft survival and an unacceptably high rate of biliary complications. These results prompted a review of the DCD protocol and adoption of the use of tPA. Although at the time there were single centers reporting good outcomes with careful donor selection and short ischemia times,18 these results were not being universally reproduced, and in general, outcomes in DCD LT have remained inferior.1 Some authors have hypothesized that the caval replacement technique
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predominantly used in this study may contribute to ischemic injury of the graft.19-21 Although it is possible that the caval replacement technique contributed to the inferior results with our early experiences, we continue to use the same technique to achieve excellent outcomes with our current DCD protocol. Since adopting the tPA protocol, we have observed a marked decrease in the number of intractable biliary complications that lead to graft failure. With improved outcomes, we have liberalized our donor selection and allowed longer warm and cold ischemia times. In our combined experience at 2 high-volume LT centers, the administration of tPA into the hepatic artery near the time of reperfusion significantly reduces the incidence of ischemic-type biliary complications and improves graft and patient survival with LT from DCD donors. Furthermore, we did not observe a clinically significant increase in intraoperative bleeding with the administration of tPA. Although our understanding of the pathophysiology of graft failure in DCD LT is incomplete and it is most certainly multifactorial, the addition of tPA appears to significantly and consistently alter the events that lead to ischemic stricture formation. Because suitable organs for LT remain scarce, our data suggest that the use of tPA near the time of reperfusion is an effective strategy to improve utilization of these marginal grafts and yield outcomes similar to those with LT from DBD donors.
REFERENCES 1. Foley DP, Fernandez LA, Leverson G, Chin LT, Krieger N, Cooper JT, et al. Donation after cardiac death: the University of Wisconsin experience with liver transplantation. Ann Surg 2005;242:724-731. 2. Callaghan CJ, Charman SC, Muiesan P, Powell JJ, Gimson AE, van der Meulen JHP; for UK Liver Transplant Audit. Outcomes of transplantation of livers from donation after circulatory death donors in the UK: a cohort study. BMJ Open 2013;3:e003287. 3. Abt PL, Desai NM, Crawford MD, Forman LM, Markmann JW, Olthoff KM, Markmann JF. Survival following liver transplantation from non-heart-beating donors. Ann Surg 2004;239:87-92. 4. Mateo R, Cho Y, Singh G, Stapfer M, Donovan J, Kahn J, et al. Risk factors for graft survival after liver transplantation from donation after cardiac death donors: an analysis of OPTN/UNOS data. Am J Transplant 2006;6:791-796. 5. Lee KW, Simpkins CE, Montgomery RA, Locke JE, Segev DL, Maley WR. Factors affecting graft survival after liver transplantation from donation after cardiac death donors. Transplantation 2006;82:1683-1688. 6. Mathur AK, Heimbach J, Steffick DE, Sonnenday CJ, Goodrich NP, Merion RM. Donation after cardiac death liver transplantation: predictors of outcome. Am J Transplant 2010;10:2512-2519. 7. Jay C, Ladner D, Wang E, Lyuksemburg V, Kang R, Chang Y, et al. A comprehensive risk assessment of mortality following donation after cardiac death liver transplant—an analysis of the national registry. J Hepatol 2011;55:808-813. 8. Axelrod DA, Lentine KL, Xiao H, Dzebisashvilli N, Schnitzler M, Tuttle-Newhall JE, Segev DL. National assessment of early biliary complications following liver
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transplantation: Incidence and outcomes. Liver Transpl 2014;20:446-456. 9. Orman ES, Barritt AS 4th, Wheeler SB, Hayashi PH. Declining liver utilization for transplantation in the United States and the impact of donation after cardiac death. Liver Transpl 2013;19:59-68. 10. Hashimoto K, Eghtesad B, Gunasekaran G, Fujiki M, Uso TD, Quintini C, et al. Use of tissue plasminogen activator in liver transplantation from donation after cardiac death donors. Am J Transplant 2010;10:26652672. 11. Foley DP, Fernandez LA, Leverson G, Anderson M, Mezrich J, Sollinger HW, D’Alessandro A. Biliary complications after liver transplantation from donation after cardiac death donors: an analysis of risk factors and long term outcomes from a single center. Ann Surg 2011; 253:817-825. 12. Taner CB, Bulatao IG, Willingham DL, Perry DK, Sibulesky L, Pungpapong S, et al. Events in procurement as risk factors for ischemic cholangiopathy in liver transplantation using donation after cardiac death donors. Liver Transpl 2012;18:100-111. 13. Harring TR, Nguyen NT, Cotton RT, Guiteau JJ, Salas de Armas IA, Liu H, et al. Liver transplantation with donation after cardiac death donors: A comprehensive update. J Surg Res 2012;178:502-511. 14. Karp SJ, Johnson S, Evenson A, Curry MP, Manning D, Malik R, et al. Minimising cold ischaemic time is essential in cardiac death donor-associated liver transplantation. HPB (Oxford) 2011;13:411-416.
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15. Gunasekaran G, Sharma J, Mosna LC, Bodin R, Wolf DC. Timing of hepatic artery reperfusion and biliary strictures in liver transplantation. J Transplant 2013; 2013:757389. 16. Leiper K, Croll A, Booth NA, Moore NR, Sinclair T, Bennett B. Tissue plasminogen activator, plasminogen activator inhibitors, and activator-inhibitor complex in liver disease. J Clin Pathol 1994;47:214-217. 17. Sakharov DV, Rijken DC. Superficial accumulation of plasminogen during plasma clot lysis. Circulation 1995; 92:1883-1890. 18. Grewal HP, Willingham DL, Nguyen J, Hewitt WR, Taner BC, Cornell D, et al. Liver transplantation using controlled donation after cardiac death donors: an analysis of a large single-center experience. Liver Transpl 2009; 15:1028-1035. 19. Leithead JA, Tariciotti L, Gunson B, Holt A, Isaac J, Mirza DF, et al. Donation after cardiac death liver transplant recipients have an increased frequency of acute kidney injury. Am J Transplant 2012;12:965-975. 20. Moreno-Gonzalez E, Meneu-Diaz JG, Fundora Y, Ortega P, Moreno Elola-Olaso A, Garcıa Garcıa I, et al. Advantages of the piggy back technique on intraoperative transfusion, fluid consumption, and vasoactive drugs requirements in liver transplantation: a comparative study. Transplant Proc 2003;35:1918-1919. 21. Nikeghbalian S, Dehghani M, Salahi H, Bahador A, Kazemi K, Kakaei F, et al. Effects of surgical technique on postoperative renal function after orthotopic liver transplant. Exp Clin Transplant 2009;7:25-27.
ORIGINAL ARTICLE
Thrombolytic Protocol Minimizes Ischemic-Type Biliary Complications in Liver Transplantation From Donation After Circulatory Death Donors John B. Seal,1 Humberto Bohorquez,2 Trevor Reichman,2 Adam Kressel,2 Anand Ghanekar,1 Ari Cohen,2 Ian D. McGilvray,1 Mark S. Cattral,1 David Bruce,2 Paul Greig,1 Ian Carmody,2 David Grant,1 Markus Selzner,1 and George Loss2 1 Multi-Organ Transplant Program, Department of Surgery, Toronto General Hospital, University of Toronto, Toronto, Canada; and 2Multi-Organ Transplant Institute, Ochsner Clinic Foundation, New Orleans, LA
Liver transplantation (LT) with donation after circulatory death (DCD) donors has been associated with a high rate of ischemic-type biliary strictures (ITBSs) and inferior graft survival. To investigate the impact of an intraoperative tissue plasminogen activator (tPA) on outcomes following DCD LT, we conducted a retrospective analysis of DCD LT at the Toronto General Hospital (TGH) and the Ochsner Medical Center (OMC). Between 2009 and 2013, 85 DCD LTs were performed with an intraoperative tPA injection (n 5 30 at TGH, n 5 55 at OMC), and they were compared with 33 DCD LTs without a tPA. Donor and recipient characteristics were similar in the 2 groups. There was no significant difference in the intraoperative packed red blood cell transfusion requirement (3.2 6 3.4 versus 3.1 6 2.3 U, P 5 0.74). Overall, biliary strictures occurred less commonly in the tPA-treated group (16.5% versus 33.3%, P 5 0.07) with a much lower rate of diffuse intrahepatic strictures (3.5% versus 21.2%, P 5 0.005). After 1 and 3 years, the tPA group versus the non-tPA group had superior patient survival (97.6% versus 87.0% and 92.7% versus 79.7%, P 5 0.016) and graft survival (96.4% versus 69.7% and 90.2% versus 63.6%, P < 0.001). In conclusion, a tPA injection into the hepatic artery during DCD LT reduces ITBSs and improves graft and patient survival without increasing the risk for bleeding. Liver Transpl 21:321-328, 2015. C 2015 AASLD. V Received June 3, 2014; accepted November 17, 2014. The use of liver transplantation (LT) as a lifesaving treatment for patients with end-stage liver disease continues to be primarily limited by donor organ availability. Donation after circulatory death (DCD) donors represent an important potential source to expand the donor pool for LT. However, posttransplant outcomes following DCD LT have to date been inferior in comparison with outcomes following LT
with donation after brain death (DBD) donors.1-8 Despite an increased use of DCD livers in the early part of the past decade, utilization has decreased in recent years as a result of inferior outcomes.9 Biliary complications are the main contributor to inferior outcomes in DCD LT, with reported biliary stricture rates between 30% and 50% (more than double the rate for LT from DBD donors). The higher rate
Abbreviations: ALP, alkaline phosphatase; AST, aspartate aminotransferase; BMI, body mass index; DBD, donation after brain death; DCD, donation after circulatory death; FFP, fresh frozen plasma; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; HTK, histidine tryptophan ketoglutarate; ICU, intensive care unit; INR, international normalized ratio; ITBS, ischemic-type biliary stricture; LT, liver transplantation; MELD, Model for End-Stage Liver Disease; OMC, Ochsner Medical Center; PRBC, packed red blood cell; PTC, percutaneous transhepatic cholangiography; SPS, static preservative solution; TGH, Toronto General Hospital; tPA, tissue plasminogen activator; UW, University of Wisconsin. The author contributions were as follows: David Grant, Trevor Reichman, Markus Selzner, and George Loss participated in the research design; John B. Seal, Trevor Reichman, Markus Selzner, George Loss participated in the writing of the article; John B. Seal, Adam Kressel, Anand Ghanekar, Ari Cohen, Ian D. McGilvray, Humberto Bohorquez, Mark S. Cattral, David Bruce, Paul Greig, Ian Carmody, David Grant, Trevor Reichman, Markus Selzner, and George Loss participated in the performance of the research; and John B. Seal, Trevor Reichman, Markus Selzner, and George Loss participated in data analysis. Address reprint requests to Markus Selzner, Multi-Organ Transplant Program, Department of Surgery, Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada. E-mail: [email protected] DOI 10.1002/lt.24071 View this article online at wileyonlinelibrary.com. LIVER TRANSPLANTATION.DOI 10.1002/lt. Published on behalf of the American Association for the Study of Liver Diseases
C 2015 American Association for the Study of Liver Diseases. V
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of biliary strictures in DCD LT is likely a result of ischemic-type biliary strictures (ITBSs), which occur in both focal and diffuse patterns. These strictures are often progressive in nature, are refractory to endoscopic/radiologic interventions, and often progress to cholestatic liver failure and require retransplantation. Although the exact pathophysiology of ITBSs is unknown, it has been hypothesized that the formation of microthrombi in the peribiliary circulation, either during the acirculatory phase of DCD withdrawal or in the early reperfusion period, leads to bile duct ischemia, inflammation, and fibrosis. On the basis of this premise, Hashimoto et al.10 hypothesized that the administration of a tissue plasminogen activator (tPA), a potent thrombolytic agent, into the hepatic artery before reperfusion would dissolve thrombi in the microcirculation and ameliorate the formation of ITBSs. Results from a pilot series of 22 patients were promising, and many centers in North America have adopted tPA administration in institutional protocols for DCD LT. However, the use of tPA in LT, especially in coagulopathic patients with liver disease, raises concern about the risk of bleeding, which is unknown in this clinical application. Following the report by Hashimoto et al.,10 Toronto General Hospital (TGH; Toronto, Ontario, Canada) and the Ochsner Medical Center (OMC; New Orleans, LA), independently adopted similar tPA protocols for DCD LT in 2009 in an effort to improve outcomes. The aims of this study were to determine the effects of tPA on biliary complications, graft survival, and patient survival following DCD LT and to assess the risk of bleeding after tPA administration into the graft.
PATIENTS AND METHODS Study Design DCD LTs performed at OMC and TGH from April 2006 through August 2013 were retrospectively reviewed from a transplant database at each institution as well as patient chart reviews. A protocol for the use of tPA infusion into the hepatic artery around the time of portal vein reperfusion was introduced in April 2009 at TGH and in October 2009 at OMC. After the introduction of the protocols, tPA was routinely used for DCD LT with the exception of 2 patients at TGH to whom tPA was not given at the discretion of the operating surgeon because of a concern about bleeding risk. The study was approved by the research ethics board at TGH and the institutional review board at OMC.
Organ Procurement and LT Technique The allocation of organs from DCD donors was coordinated by the Trillium Gift of Life Network for TGH and the regional organ procurement organization for OMC. Recipient allocation was based on the calculated sodium Model for End-Stage Liver Disease (MELD) score with the exception of patients listed for hepatocellular carcinoma (HCC), who received exception
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points per the standard protocol at the time. The identification of potential DCD donors, the process of withdrawal of life support, and the declaration of donor death were completed by an intensive care physician at the donor hospital and were completely independent of the recovery and recipient teams. Donor withdrawal was performed in the setting of the intensive care unit (ICU) or in an operating room separate from the recovery team. Donor vitals during the withdrawal process were recorded and communicated to the recovery team until circulatory arrest. The start of the donor warm ischemia time was defined by the time of extubation at TGH and by oxygen saturation < 80% or a systolic blood pressure < 80 mm Hg at OMC. A cutoff of 30 minutes from the start of warm ischemia to the start of the in situ flush was used for organ acceptance at both centers. For the purpose of analysis, the TGH definition of donor warm ischemia time was used for both groups. Because of the difference in the definitions of the start of warm ischemia, warm ischemia times for OMC were longer when they were measured from the point of extubation. For DCD donors accepted by TGH, heparin was routinely given at the time of extubation at a dose of 1000 U/kg or at a reduced dose of 500 U/kg in the context of intracranial hemorrhage. In contrast, for DCD donors accepted by OMC, a reduced dose of heparin (typically 2000-3000 U) was given. In Ontario, withdrawal of life support in the donor occurred most often in the ICU or recovery room of the operating room and thus required additional transport time during warm ischemia. Withdrawal for most DCD donors accepted by OMC was carried out in the operating room. After determination of circulatory arrest, a mandatory 5- to 10-minute “hands-off” period was observed before the final declaration of death; this depended on the local hospital policy. The recovery procedure was performed by experienced surgeons and emphasized rapid abdominal exposure, aortic/iliac artery cannulation, and systemic perfusion with a hypothermic static preservative solution (SPS) or University of Wisconsin (UW) solution. The bile duct was transected and flushed in situ, and a second portal venous, arterial, and biliary flush was performed immediately after graft removal on the back table. At OMC, a retrograde hepatic vein flush was also performed on the back table. For the recipient transplant procedure, a caval replacement technique was used with the exception of 4 cases, for which a bicaval piggyback technique was used. Biliary reconstruction was performed from duct to duct in all cases with the exception of 7 Roux-en-Y enteric drainage cases, which were performed at TGH.
tPA Dosing and Administration Thrombolytic protocols independently adopted at OMC and TGH were similar with the exception of the dosage and timing of tPA administration (Table 1 and Fig. 1). At both centers, tPA was reconstituted at room temperature with sterile water at a concentration of
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TABLE 1. DCD LT Thrombolytic Protocols
Donor age limit Heparin dose (antemortem) Start of warm ischemia
Warm ischemia limit Flush solution Organ recovery technique Back-table flush tPA dosing tPA administration
OMC
TGH
60 years 30,000 U Systolic blood pressure < 80 mm Hg or saturation < 80% 30 minutes UW/HTK Standard Yes 2 mg 1 5 mg of verapamil Before hepatic artery anastomosis
55 years 1000 U/kg of donor weight Extubation
Figure 1. Timing of tPA administration. OMC and TGH independently adopted thrombolytic protocols for the use of tPA in DCD LT with differences in the timing of tPA administration.
1 mg/mL. At TGH, the tPA dose was based on the donor’s weight (100 mg/kg) to account for variations in the graft size. The median volume of administered tPA was 7 mL (range 5 4-10 mL). Before completion of the portal vein anastomosis, tPA was administered. With the liver graft in situ after upper and lower caval anastomoses, the portal vein anastomosis was set up, and the corner sutures were placed. Recombinant tPA (Alteplase, Hoffmann-La Roche, Mississauga, Canada) was then administered into the hepatic artery above the level of the gastroduodenal artery stump to maximize the distribution to the intrahepatic vasculature. A microvascular clamp was placed on the hepatic artery to prevent backflow. The portal vein anastomosis was then completed (approximately 5-10 minutes), and the liver was flushed with 200 to 300 mL of portal venous flow vented through a chest tube in the lower caval anastomosis. The hepatic artery anastomosis was then performed, and this completed the vascular reperfusion of the graft. The original report by Hashimoto et al.10 described the administration of tPA into the hepatic artery during the back-table preparations. The TGH protocol was modified to administer the tPA closer to the time of the portal reperfusion to limit the effects of hypothermia and dilution. At OMC, the liver graft was routinely flushed in situ with hypothermic 5% albumin during the upper and lower caval anastomoses, and this eliminated the need for a portal blood flush before reperfusion. After completion of the portal vein anastomosis and the restoration of the portal perfusion, 5 mg (5 mL) of
30 minutes UW/SPS En bloc liver/pancreas Yes 100 mg/kg of donor weight Before portal vein anastomosis (5-10 minutes before portal reperfusion)
verapamil was introduced as a vasodilator directly into the hepatic artery, and this was immediately followed by a fixed dose of 2 mg (2 mL) of tPA (Alteplase, Genentech, San Francisco, CA). A microvascular clamp was placed above the level of the gastroduodenal stump to prevent backflow. The arterial anastomosis was completed, and the arterial perfusion of the graft was restored. No formal back-bleeding procedure was performed.
Posttransplant Outcomes Graft function and acute reperfusion injury were assessed in the early postoperative period (48 hours) by peak serum aspartate aminotransferase (AST). Short-term graft function was assessed by total serum bilirubin, alkaline phosphatase (ALP), and the international normalized ratio (INR) 6 and 12 months after the transplant. Graft failure was determined by the time of listing for retransplantation or patient death. Biliary complications were identified by abnormal liver function tests or a clinical presentation consistent with cholangitis and were diagnosed by cholangiography. Categorization of biliary strictures was based on the interpretation of imaging from percutaneous transhepatic cholangiography (PTC), endoscopic retrograde cholangiography, or magnetic resonance cholangiopancreatography. For the purposes of analysis, biliary strictures were classified as diffuse intrahepatic strictures or focal extrahepatic strictures. Diffuse intrahepatic strictures were not amenable to definitive management with endoscopic or radiographic stenting, and more often, they progressed to graft failure. Anastomotic strictures and focal ischemic-type strictures in the extrahepatic biliary tree were often difficult to delineate on cholangiography and thus were grouped together for the purposes of analysis. All of these strictures were successfully managed with endoscopic or percutaneous dilation and stenting with the exception of one that was corrected with conversion to Roux-en-Y enteric biliary drainage.
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TABLE 2. Donor and Recipient Characteristics
Recipient Age (years) Sex (male) BMI (kg/m2) Diagnosis HCV HCC MELD Donor Age (years) Sex (male) BMI (kg/m2) Cause of death Trauma Anoxia Cerebrovascular accident Warm ischemia time (minutes) Cold ischemia time (hours) Regional share National share
tPA (n 5 85)
No tPA (n 5 33)
P
54.6 6 10.9 57 (67.1%) 24.7 6 10.5
53.2 6 10.6 24 (72.7%) 27.4 6 4.9
0.55 0.66 0.56
43 (50.6%) 32 (37.6%) 20.1 6 8.2
18 (54.5%) 8 (24.2%) 16.5 6 10.8
0.84 0.19 0.38
36.3 6 14.8 51 (60.0%) 26.8 6 6.0
38.0 6 14.9 11 (33.3%) 27.1 6 7.6
0.99 0.01 0.05
15 (17.6%) 38 (44.7%) 24 (28.2%) 21.1 6 8.3 5.1 6 1.2 30 (35.3%) 1 (1.2%)
6 (18.2%) 11 (33.3%) 11 (33.3%) 23.5 6 7.6 4.3 6 1.0 2 (6.1%) 0
1 0.3 0.65 0.16 0.004 0.001 1.0
TABLE 3. Intraoperative Blood Product Usage
PRBCs (U) FFP (U) Platelets (U) Autologous red blood cells (mL)
tPA (n 5 85)
No tPA (n 5 33)
P
3.2 6 3.4 (0-24) 5.9 6 4.3 9.5 6 1.9 462.4 6 618.0
3.1 6 2.3 (0-8) 7.9 6 4.0 4.2 6 4.8 060
0.74 0.25 0.03 0.41
Statistical Analysis Statistical analysis was performed with XLSTAT software version 8.0 (XLSTAT for Windows Excel, New York, NY), and GraphPad Prism 5.04 for Windows (GraphPad Software, La Jolla, CA). Fisher’s exact test was used for categorical variables, whereas a Student t test was performed for continuous parametric variables, and a Mann-Whitney U test was used for nonparametric continuous variables. Graft survival and patient survival were calculated with the KaplanMeier survival analysis and were compared with the log-rank test. P 0.05 was considered statistically significant.
at the time of transplant, or the diagnosis of hepatitis C virus (HCV) or HCC. A higher percentage of donors were male in the tPA group (60.0% versus 34.4%, P 5 0.01), but otherwise, there was no difference in donor age, body mass index (BMI), or cause of death. The cold ischemia time was significantly longer in the tPA group (5.1 6 1.2 versus 4.3 6 1.0 hours, P 5 0.004). There was no significant difference in donor warm ischemia times (extubation to in situ cold perfusion) between the tPA group and the untreated group (21.1 6 8.3 versus 23.5 6 7.6 minutes). Regional-share donors were used more frequently in the tPA group (35.3% versus 6.1%, P 5 0.001), and a national-share donor was used in only 1 patient in the tPA group.
RESULTS Donor and Recipient Characteristics
Intraoperative Bleeding
During the study period, 118 DCD LTs were performed in all at OMC and TGH. Among these DCD LT cases, 85 received tPA, and 33 did not. Donor and recipient characteristics for each group are presented in Table 2. There was no difference between the 2 groups with respect to recipient age, the MELD score
Intraoperative administration of blood products was compared to determine the effects of tPA on the risk of bleeding (Table 3). There was no difference in the mean number of units of packed red blood cells (PRBCs), fresh frozen plasma (FFP), or volume of autologous red blood cells infused for the 2 groups
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TABLE 4. Posttransplant Outcomes
Mean follow-up (months) Length of hospitalization (median number of days, range) Peak AST at 48 hours (U/L) AST at 7 days Total bilirubin (mg/dL) 7 days 6 months 12 months ALP (U/L) 6 months 12 months INR at 12 months Retransplant
No tPA (n 5 33)
Ochsner tPA (n 5 56)
P
Toronto tPA (n 5 29)
P
73.7 6 16.9 12 (5-162)
32.4 6 12.1 8 (4-95)
0.001 0.03
39.4 6 15.5 10 (4-118)
0.001 0.03
1792.1 6 1720.5 605.2 6 1018.7
2241.7 6 1995.1 56.3 6 36.2
0.28 0.001
1852.0 6 1817.7 63.8 6 84.1
0.89 0.006
4.2 6 3.3 4.7 6 7.2 3.5 6 6.8
2.7 6 3.2 1.4 6 2.5 0.8 6 0.7
0.04 0.002 0.004
3.3 6 2.9 0.8 6 0.5 1.8 6 4.4
0.26 0.005 0.25
235.0 6 189.8 285.4 6 521.9 1.1 6 0.2 6 (18.2%)
156.9 6 133.3 144.5 6 107.7 1.2 6 0.5 2 (3.6%)
0.03 0.05 0.28 0.05
191.5 6 150.0 178.0 6 140.6 1.2 6 0.2 0 (0%)
0.32 0.15 0.05 0.03
(Table 3). The mean number of units of platelets was higher in the tPA-treated group (9.5 6 1.9 versus 4.2 6 4.8 U, P 5 0.03). The proportion of cases using 5 U of PRBCs was not higher for the tPA group versus the untreated group (14.1% versus 12.1%, P 5 0.63).
Posttransplant Outcomes A tPA protocol for DCD LT was introduced in January 2009 in Toronto and in October 2009 for OMC. The mean follow-up was longer for the untreated group (64.2 6 14.4 versus 22.5 6 13.7 months, P < 0.001). After implementation of the protocol, tPA was not administered in 2 cases at the discretion of the operating surgeon, and they were included in the untreated group for analysis. The mean lengths of hospitalization and ICU stays were shorter in the tPA group, although the difference was not significant (Table 4). There was no significant difference in peak posttransplant serum AST (2174.5 6 1922.1 versus 1792.1 6 1720.5 U/L, P 5 0.2). The mean total serum bilirubin was significantly higher in the untreated group 6 and 12 months after the transplant. Similarly, the mean ALP was also higher in the untreated group 6 and 12 months after the transplant (Table 4). Synthetic function was assessed by a measurement of the INR 12 months after the transplant and was normal for the tPA and untreated groups (1.19 6 0.68 versus 1.07 6 0.2, P 5 0.87). The mean serum creatinine after transplantation for both groups was 1.28 mg/dL at 48 hours and 1.21 mg/dL at 7 days.
Biliary Complications The overall rate of biliary complications in the tPA group was 16.5% versus 33.3% in the control group. Biliary complications were classified as diffuse intrahepatic or focal extrahepatic. Diffuse strictures were not definitively managed with endoscopic or radiographic dilation and stenting, and they more often progressed to prolonged biliary complications and graft failure. Focal strictures, including anastomotic
strictures, occurred in the extrahepatic biliary system and were amenable to dilation and stenting interventions with the exception of 1 case in the tPA-treated group that required surgical revision to the Roux-en-Y biliary enteric drainage. Although some focal strictures required multiple interventions, none led to refractory biliary complications and graft failure. Because the tPA protocol adopted at each center was different, biliary complications were reported separately. There was no significant difference in the rate of focal extrahepatic strictures in the untreated group (12.1%) and the tPA group at OMC (16.1%, P 5 0.75) and TGH (10.3%, P 5 0.99; Fig. 2). However, the rate of diffuse intrahepatic strictures was significantly lower in the tPA group at OMC (3.6%) and TGH (0%) versus the untreated group (21.2%, P 5 0.005). Two patients in the tPA group developed delayed hepatic artery thrombosis (at postoperative days 38 and 114) and subsequent biliary complications leading to graft loss and retransplantation. One patient in the tPA group developed a focal stricture near the level of the hepatic duct confluence, which required surgical revision of the biliary anastomosis after failure of the PTC drainage and stent.
Patient and Graft Survival Overall, graft survival was higher in the tPA group versus the untreated group at 1 year (96.4% versus 69.7%) and 3 years (90.2% versus 63.6%, P < 0.001) after transplantation. Patient survival after the transplant was also significantly higher in the tPA group versus the untreated group at 1 year (97.6% versus 87.0%) and 3 years (92.7% versus 79.7%, P 5 0.016) after transplant (Fig. 3). There were no significant differences between the TGH and OMC tPA groups in overall patient survival (95.5% versus 98.1%, P 5 0.70) or graft survival (95.5% versus 96.1%, P 5 0.39), respectively. The recipient rate of death from sepsis related to biliary complications was significantly higher in the
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Figure 2. Biliary stricture formation following DCD LT. The overall rate of biliary strictures was lower among DCD LT patients treated with tPA in the hepatic artery near the time of graft reperfusion. There was no significant difference in the rates of focal strictures, but there was a significantly lower rate of diffuse intrahepatic strictures in the tPA-treated groups (3.5% versus 21.2%, P 5 0.005). There were no diffuse intrahepatic biliary strictures in the tPA-treated group at TGH. *3.5% versus 21.2%, P < 0.005.
untreated group (n 5 3) versus the tPA-treated group (n 5 0, P 5 0.02). Two patients in the untreated group and 1 in the tPA group died from sepsis unrelated to biliary complications. There were 2 deaths secondary to cardiopulmonary events in each group. One patient in the tPA group died of an intraoperative pulmonary embolism, and 1 died from graft-versus-host disease. In the untreated group, 4 of the 8 patients with HCC died of tumor recurrence versus only 2 of the 32 HCC patients in the tPA group. Both groups were similar with respect to the tumor stage at the time of transplantation.
DISCUSSION The utilization of livers from DCD donors has been limited by inferior outcomes due in large part to biliary complications. Several measures have been proposed to reduce the incidence of ITBSs in DCD LT: avoiding older or unstable donors, expediting organ retrieval to limit donor warm ischemia time, using in situ biliary and back-table vascular flushing, and limiting the cold ischemia time and simultaneous arterial and portal revascularization.5,11-15 Despite widespread application of many of these strategies, outcomes from DCD LT remain inferior to those from LT using DBD donors. Hashimoto et al.10 first described the use of tPA as a novel clinical strategy to improve peribiliary microcirculation and reduce the incidence of ITBSs in LT. In our review of the use of tPA in DCD LT at 2 high-volume LT centers in North America, we demonstrate a significant reduction of diffuse ITBSs and improved patient and graft survival in comparison with DCD LT without tPA. Overall, we observed a lower rate of biliary complications in the tPA group in comparison with the
Figure 3. Patient and graft survival following DCD LT. Overall patient survival (top) and graft survival (bottom) were higher for DCD LT patients treated with tPA 1 and 3 years after the transplant.
untreated DCD LT group. Although we did not observe a difference in the rate of focal strictures, the rate of diffuse strictures was significantly lower in the tPA group at both centers. Furthermore, in the tPA group, diffuse strictures were seen exclusively in the setting of delayed hepatic artery thrombosis. The difference in the rate of diffuse intrahepatic strictures is clinically significant because diffuse strictures are least amenable to stenting and drainage and often progress to graft failure and retransplantation. The reduction in diffuse intrahepatic strictures supports the hypothesis that tPA clearance of peribiliary microthrombi reduces ischemic events that can lead to stricture formation throughout the liver. In keeping with this finding, we also observed a lower rate of graft loss in the tPA-treated group versus the controls. Tissue plasminogen activator is naturally produced by the liver and acts in the fibrinolytic pathway by converting plasminogen to the active form of plasmin. Plasminogen is ubiquitous in circulation and tissue
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and can form a local reservoir by binding to the surface of a clot to target the fibrinolytic effect.16,17 Although the precise pharmacokinetics of tPA are unknown in this application, it is likely to have reduced activity in hypothermic conditions and with a low substrate (plasminogen) concentration in the preserved graft. We speculate that a majority of the fibrinolytic activity occurs upon portal vein reperfusion with a return to normothermic conditions and an ample supply of plasminogen. The use of a fibrinolytic agent in LT and especially in the setting of coagulopathy of liver disease raises concern about a bleeding risk. In their original report, Hashimoto et al.10 reported excessive bleeding in 64% of patients receiving tPA. However, this was not a dose-dependent risk and was likely confounded by reperfusion effects related to graft quality. In our combined experience, we did not observe any significant increase in intraoperative bleeding associated with the use of tPA. One outlier case in the tPA group required 24 U of PRBCs intraoperatively, but most transfusions occurred before reperfusion during the recipient hepatectomy because of coagulopathy, varices, and prior abdominal surgery. Approximately 25% of the patients in the tPA group did not require any PRBC transfusion, and this suggests that if there is a real increased risk of bleeding, it is not uniform and likely depends on other factors such as reperfusion effects, underlying coagulopathies, and higher risk hepatectomies. Under normal conditions, tPA is rapidly cleared by the liver with a systemic half-life of 5 minutes. Therefore, it is unlikely to have significant systemic effects in this application. The primary limitation of this study is the retrospective design. Although data were prospectively collected in a transplant research database, there was no randomization of tPA therapy. DCD LTs performed without tPA occurred early in each center’s experience with DCD LT. Thus, the improved outcomes that we observed in the tPA treatment group may be confounded by center experience with DCD LT. However, we did not observe significant differences in donor or recipient characteristics or donor warm ischemia times, factors more likely to be affected by refinement of the organ recovery process and patient selection. Furthermore, the cold ischemia time was significantly longer and the regional share was significantly higher in the tPA-treated group, and this suggests a less conservative approach when a center has more experience. Despite efforts to carefully select donors and minimize cold and warm ischemia times, our initial experience with DCD LT at both centers yielded inferior graft survival and an unacceptably high rate of biliary complications. These results prompted a review of the DCD protocol and adoption of the use of tPA. Although at the time there were single centers reporting good outcomes with careful donor selection and short ischemia times,18 these results were not being universally reproduced, and in general, outcomes in DCD LT have remained inferior.1 Some authors have hypothesized that the caval replacement technique
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predominantly used in this study may contribute to ischemic injury of the graft.19-21 Although it is possible that the caval replacement technique contributed to the inferior results with our early experiences, we continue to use the same technique to achieve excellent outcomes with our current DCD protocol. Since adopting the tPA protocol, we have observed a marked decrease in the number of intractable biliary complications that lead to graft failure. With improved outcomes, we have liberalized our donor selection and allowed longer warm and cold ischemia times. In our combined experience at 2 high-volume LT centers, the administration of tPA into the hepatic artery near the time of reperfusion significantly reduces the incidence of ischemic-type biliary complications and improves graft and patient survival with LT from DCD donors. Furthermore, we did not observe a clinically significant increase in intraoperative bleeding with the administration of tPA. Although our understanding of the pathophysiology of graft failure in DCD LT is incomplete and it is most certainly multifactorial, the addition of tPA appears to significantly and consistently alter the events that lead to ischemic stricture formation. Because suitable organs for LT remain scarce, our data suggest that the use of tPA near the time of reperfusion is an effective strategy to improve utilization of these marginal grafts and yield outcomes similar to those with LT from DBD donors.
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