Persistent left superior vena cava in right hemiarch replacement under deep hypothermic circulatory arrest:A case report

BACKGROUND Persistent left superior vena cava(PLSVC),a relatively rare thoracic vascular malformation,can inconvenience perfusionists and operators when encountered during deep hypothermic circulatory arrest(DHCA).CASE SUMMARY Herein,we describe the case of a patient with concurrent giant aortic arch aneurysm,aortic stenosis,and PLSVC.To treat these conditions,we performed right hemiarch and aortic valve replacements under DHCA.Notably,we applied“bilateral superior vena cava retrograde cerebral perfusion(RCP)”for cerebral protection,which significantly optimized the surgical procedure and reduced the risk of postoperative complications.The patient was discharged 14 d after surgery with no complications.CONCLUSION Surgical intervention for PLSVC under DHCA can be performed using the bilateral superior vena cava RCP approach.

Influence of perfusate on liver viability during hypothermic machine perfusion

AIM: To optimize the perfusates used for hypothermicmachine perfusion(HMP).METHODS: Sprague-Dawley rats were assigned randomly to three groups(n = 12 per group) that received either saline, University of Wisconsin coldstorage solution(UW) or histidine-tryptophan-ketoglutarate solution(HTK) as the perfusate. Each group was divided into two subgroups: static cold storage(SCS) and HMP(n = 6 per subgroup). The liver graft was retrieved according to the method described by Kamada. For the SCS group, the graft was directly placed into cold perfusate(0-4?℃) for 6 h after liver isolation while the portal vein of the graft was connected to the perfusion machine for the HMP group. Then the perfusates were collected at different time points for analysis of aspartate aminotransferase(AST), alanine transaminase(ALT) and lactate dehydrogenase(LDH) levels. Liver tissues were obtained for evaluation of histology, dry/wet weight(D/W) ratio, and malondialdehyde(MDA) and adenosine-triphosphate(ATP) levels. The portal vein pressure and velocity were monitored in real time in all HMP subgroups.RESULTS: Comparison of HMP and SCS: Regardless of the perfusate, HMP improved the architecture of donor graft in reducing the congestion around sinusoids and central vein and maintaining sinusoid lining in morphology; HMP improved liver function in terms of ALT, AST and LDH, especially during the 3-6 h period(SCS vs HMP using saline: ALT3, 225.00 ± 105.62 vs 49.50 ± 18.50, P = 0.047; LDH3, 1362.17 ± 563.30 vs 325.75 ± 147.43, P = 0.041; UW: LDH6, 2880.14 ± 948.46 vs 2135.00 ± 174.27, P = 0.049; HTK, AST6, 307.50 ± 52.95 vs 185.20 ± 20.46, P = 0.041); HMP decreased MDA level(saline, 2.79 ± 0.30 vs 1.09 ± 0.09, P = 0.008; UW, 3.01 ± 0.77 vs 1.23 ± 0.68, P = 0.005; HTK, 3.30 ± 0.52 vs 1.56 ± 0.22, P = 0.006). Comparison among HMP subgroups: HTK showed less portal vein resistance than UW and saline(vs saline, 3.41 ± 0.49 vs 5.00 ± 0.38, P < 0.001; vs UW, 3.41 ± 0.49 vs 4.52 ± 0.63, P = 0.007); UW reduced edema most efficiently(vs saline, 0.68 ± 0.02 vs 0.79 ± 0.05, P = 0.013), while HTK maintained ATP levels best(vs saline, 622.60 ± 29.11 vs 327.43 ± 44.66, P < 0.001; vs UW, 622.60 ± 29.11 vs 301.80 ± 37.68, P < 0.001).CONCLUSION: HMP is superior to SCS in maintaining both architecture and function of liver grafts. Further, HTK was found to be the optimal perfusate for HMP.

MicroRNA expression in the hippocampal CA1 region under deep hypothermic circulatory arrest

Using deep hypothermic circulatory arrest, thoracic aorta diseases and complex heart diseases can be subjected to corrective procedures. However, mechanisms underlying brain protection during deep hypothermic circulatory arrest are unclear. After piglet models underwent 60 minutes of deep hypothermic circulatory arrest at 14°C, expression of microRNAs(miRNAs) was analyzed in the hippocampus by microarray. Subsequently, TargetScan 6.2, RNA22 v2.0, miRWalk 2.0, and miRanda were used to predict potential targets, and gene ontology enrichment analysis was carried out to identify functional pathways involved. Quantitative reverse transcription-polymerase chain reaction was conducted to verify miRNA changes. Deep hypothermic circulatory arrest altered the expression of 35 miRNAs. Twenty-two miRNAs were significantly downregulated and thirteen miRNAs were significantly upregulated in the hippocampus after deep hypothermic circulatory arrest. Six out of eight targets among the differentially expressed miRNAs were enriched for neuronal projection(cyclin dependent kinase, CDK16 and SLC1 A2), central nervous system development(FOXO3, TYRO3, and SLC1 A2), ion transmembrane transporter activity(ATP2 B2 and SLC1 A2), and interleukin-6 receptor binding(IL6 R)– these are the key functional pathways involved in cerebral protection during deep hypothermic circulatory arrest. Quantitative reverse transcription-polymerase chain reaction confirmed the results of microarray analysis. Our experimental results illustrate a new role for transcriptional regulation in deep hypothermic circulatory arrest, and provide significant insight for the development of miRNAs to treat brain injuries. All procedures were approved by the Animal Care Committee of Xuanwu Hospital, Capital Medical University, China on March 1, 2017(approval No. XW-INI-AD2017-0112).

Hypothermic machine perfusion with metformin-University of Wisconsin solution for ex vivo preservation of standard and marginal liver grafts in a rat model

AIM To compare the effect of University of Wisconsin(UW) solution with or without metformin, an AMP-activated protein kinase(AMPK) activator, for preserving standard and marginal liver grafts of young and aged rats ex vivo by hypothermic machine perfusion(HMP).METHODS Eighteen young(4 mo old) and 18 aged(17 mo old)healthy male SD rats were selected and randomly divided into three groups: control group, UW solution perfusion group(UWP), and UW solution with metformin perfusion group(MUWP). Aspartate aminotransferase(AST), alanine aminotransferase(ALT), lactate dehydrogenase(LDH), interleukin-18(IL-18), and tumor necrosis factor-alpha(TNF-α) in the perfused liquid were tested. The expression levels of AMPK and endothelial nitric oxide synthase(e NOS) in liver sinusoidal endothelial cells were also examined.Additionally, microscopic evaluation of the harvested perfused liver tissue samples was done. RESULTS AST, ALT, LDH, IL-18 and TNF-α levels in the young and aged liver-perfused liquid were, respectively,significantly lower in the MUWP group than in the UWP group(P < 0.05), but no significant differences were found between the young and aged MUWP groups.Metformin increased the expression of AMPK and e NOS protein levels, and promoted the extracellular release of nitric oxide through activation of the AMPK-e NOS mediated pathway. Histological examination revealed that in the MUWP group, the extent of liver cells and tissue damage was significantly reduced compared with the UWP group.CONCLUSION The addition of metformin to the UW preservative solution for ex vivo HMP can reduce rat liver injury during cold ischemia, with significant protective effects on livers, especially of aged rats.

THE TECHNIQUE OF THE NORMOTHERMIC AND HYPOTHERMIC TOTAL HEPATIC VASCULAR EXCLUSION FOR RESECTION OF THE LIVER TUMORS

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Routine utilization of machine perfusion in liver transplantation:Ready for prime time?

The last decade has been notable for increasing high-quality research and dramatic improvement in outcomes with dynamic liver preservation.Robust evidence from numerous randomized controlled trials has been pooled by meta-analyses,providing the highest available evidence on the protective effect of machine perfusion(MP)over static cold storage in liver transplantation(LT).Based on a protective effect with less complications and improved graft survival,the field has seen a paradigm shift in organ preservation.This editorial focuses on the role of MP in LT and how it could become the new“gold standard”.Strong collaborative efforts are needed to explore its effects on long-term outcomes.

Beneficial Effect of Moderately Increasing Hypothermic Machine Perfusion Pressure on Donor after Cardiac Death Renal Transplantation

Background:Vascular resistance and flow rate during hypotherrnic machine perfusion (HMP)of kidneys is correlated with graft function. We aimed to determine the effects of increasing HMP pressure versus maintaining the initial pressure on kidney transplantation outcomes. Methods:We retrospectively reviewed the data of 76 primary transplantation patients who received HMP-preserved kidneys from 48 donors after cardiac death between September 1,2013,and August 31,2015.HMP pressure was increased from 30 to 40mmHg (1mmHg =0.133kPa)in kidneys with poor flow and/or vascular resistance (increased pressure [IP]group;36 patients);otherwise,the initial pressure was maintained (constant pressure group;40 patients).Finally,the clinical characteristics and transplantation outcomes in both groups were assessed. Results:Delayed graft function (DGF)incidence,1-year allograft,patient survival,kidney function recovery time,and serum creatinine level on day 30 were similar in both groups,with improved flow and resistance in the IP group.Among patients with DGF,kidney function recovery time and DGF duration were ameliorated in the IP group.Multivariate logistic regression analysis revealed that donor hypertension (odds ratio [OR]:1.43,95%confidence interval [CI]:1.02-2.06,P =0.035),donor terminal serum creatinine (OR:1.27,95%C7:1.06-1.62,P =0.023),warm ischemic time (OR:3.45,95%CI:1.97-6.37,P =0.002),and terminal resistance (OR:3.12,95%CI:1.76-6.09,P =0.012)were independent predictors of DGF.Cox proportional hazards analysis showed that terminal resistance (hazard ratio:2.06,95%C1:1.32-5.16,P =0.032)significantly affected graft survival. Conclusion:Increased HMP pressure improves graft perfusion but does not affect DGF incidence or 1-year graft survival.

Predictive Score Model for Delayed Graft Function Based on Hypothermic Machine Perfusion Variables in Kidney Transplantation

Background:Hypothermic machine perfusion (HMP)is being used more often in cardiac death kidney transplantation;however,the significance of assessing organ quality and predicting delayed graft function (DGF)by HMP parameters is still controversial.Therefore, we used a readily available HMP variable to design a scoring model that can identify the highest risk of DGF and provide the guidance and advice for organ allocation and DCD kidney assessment. Methods:From September 1,2012 to August 31,2016,366 qualified kidneys were randomly assigned to the development and validation cohorts in a 2:1 distribution.The HMP variables of the development cohort served as candidate univariate predictors for DGF.The independent predictors of DGF were identified by multivariate logistic regression analysis with a P <0.05.According to the odds ratios (ORs)value,each HMP variable was assigned a weighted integer,and the sum of the integers indicated the total risk score for each kidney.The validation cohort was used to verify the accuracy and reliability of the scoring model. Results:HMP duration (OR =1.165,95% confidence interval [CI]:1.008-1.360,P =0.043),resistance (OR =2.190,95% CI:1.032-10.20,P <0.001),and flow rate (OR =0.931,95%CI:0.894-0.967,P =0.011)were the independent predictors of identified DGF.The HMP predictive score ranged from 0 to 14,and there was a clear increase in the incidence of DGF,from the low predictive score group to the very high predictive score group.We formed four increasingly serious risk categories (scores 0-3,4-7,8-11,and 12-14) according to the frequency associated with the different risk scores of DGF.The HMP predictive score indicates good discriminative power with a c-statistic of 0.706 in the validation cohort,and it had significantly better prediction value for DGF compared to both terminal flow (P =0.012)and resistance (P =0.006). Conclusion:The HMP predictive score is a good noninvasive tool for assessing the quality of DCD kidneys,and it is potentially useful for physicians in making optimal decisions about the organs donated.

Predictive value of hypothermic machine perfusion parameters combined perfusate biomarkers in deceased donor kidney transplantation

Background:Delayed graft function(DGF)is the main cause of renal function failure after kidney transplantation.This study aims at investigating the value of hypothermic machine perfusion(HMP)parameters combined with perfusate biomarkers on predicting DGF and the time of renal function recovery after deceased donor(DD)kidney transplantation.Methods:HMP parameters,perfusate biomarkers and baseline characteristics of 113 DD kidney transplantations from January 1,2019 to August 31,2019 in the First Affiliated Hospital of Xi’an Jiaotong University were retrospectively analyzed using univariate and multivariate logistic regression analysis.Results:In this study,the DGF incidence was 17.7%(20/113);The multivariate logistic regression results showed that terminal resistance(OR:1.879,95%CI 1.145-3.56)and glutathione S-transferase(GST)(OR=1.62,95%CI 1.23-2.46)were risk factors for DGF;The Cox model analysis indicated that terminal resistance was an independent hazard factor for renal function recovery time(HR=0.823,95%CI 0.735-0.981).The model combining terminal resistance and GST(AUC=0.888,95%CI:0.842-0.933)significantly improved the DGF predictability compared with the use of terminal resistance(AUC=0.756,95%CI 0.693-0.818)or GST alone(AUC=0.729,95%CI 0.591-0.806).Conclusion:According to the factors analyzed in this study,the combination of HMP parameters and perfusate biomarkers displays a potent DGF predictive value.

Effect of continuous hypothermic machine perfusion transport system（AirdriveTM） on canine kidney preservation

Background Organ preservation keeps the quality of the organs under prolonged ischemia. Continuous machineperfusions are gaining an important position in clinical research and practice. The aim of this study was to evaluate theprotective effect of continuous hypothermic machine perfusion transport system （AirdriveTM） on cold ischemic injury ofcanine kidney.

Machine perfusion and the prevention of ischemic type biliary lesions following liver transplant:What is the evidence?

The widespread uptake of different machine perfusion(MP)strategies for liver transplant has been driven by an effort to minimize graft injury.Damage to the cholangiocytes during the liver donation,preservation,or early posttransplant period may result in stricturing of the biliary tree and inadequate biliary drainage.This problem continues to trouble clinicians,and may have catastrophic consequences for the graft and patient.Ischemic injury,as a result of compromised hepatic artery flow,is a well-known cause of biliary strictures,sepsis,and graft failure.However,very similar lesions can appear with a patent hepatic artery and these are known as ischemic type biliary lesions(ITBL)that are attributed to microcirculatory dysfunction rather than main hepatic arterial compromise.Both the warm and cold ischemic period duration appear to influence the onset of ITBL.All of the commonly used MP techniques deliver oxygen to the graft cells,and therefore may minimize the cholangiocyte injury and subsequently reduce the incidence of ITBL.As clinical experience and published evidence grows for these modalities,the impact they have on ITBL rates is important to consider.In this review,the evidence for the three commonly used MP strategies(abdominal normothermic regional perfusion[A-NRP],hypothermic oxygenated perfusion[HOPE],and normothermic machine perfusion[NMP])for ITBL prevention has been critically reviewed.Inconsistencies with ITBL definitions used in trials,coupled with variations in techniques of MP,make interpretation challenging.Overall,the evidence suggests that both HOPE and A-NRP prevent ITBL in donated after circulatory death grafts compared to cold storage.The evidence for ITBL prevention in donor after brain death grafts with any MP technique is weak.

Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion

The growing demand for donor organs requires measures to expand donor pool.Those include extended criteria donors, such as elderly people, steatotic livers,donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960 s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion(NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury.Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose.Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations.

Current and future perspectives on acute-on-chronic liver failure: Challenges of transplantation, machine perfusion, and beyond

Acute-on-chronic liver failure(ACLF)is a syndrome that occurs in patients with chronic liver disease and is characterized by acute decompensation,organ failure and high short-term mortality.Partially due to the lack of universal diagnostic criteria,the actual ACLF prevalence remains unclear;nevertheless,it is expected to be a highly prevalent condition worldwide.Earlier transplantation is an effective protective measure for selected ACLF patients.Besides liver transplantation,diagnosing and treating precipitant events and providing supportive treatment for organ failures are currently the cornerstone of ACLF therapy.Although new clinical specific therapies have been researched,more studies are necessary to assess safety and efficacy.Therefore,future ACLF management strategies must consider measures to improve access to liver transplantation because the time window for this life-saving therapy is frequently narrow.Thus,an urgent and global discussion about allocation and prioritization for transplantation in critically ill ACLF patients is needed because there is evidence suggesting that the current model may not portray their waitlist mortality.In addition,while donor organ quality is meant to be a prognostic factor in the ACLF setting,recent evidence suggests that machine perfusion of the liver may be a safe tool to improve the donor organ pool and expedite liver transplantation in this scenario.

Liver transplantation with grafts obtained after cardiac death-current advances in mastering the challenge

The scarcity of donor livers has increased the interest in donation after cardiac death(DCD) as an additional pool to expand the availability of organs. However, the initial results of liver transplantation with DCD grafts have been suboptimal due to an increased rate of complications, as well as decreased graft survival. These challenges have led to many developments in DCD donation outcome, as well as basic and translational research. In this article we review the unique characteristics of DCD donors, nuances of DCD organ procurement, the effect of prolonged warm and cold ischemia times, and discuss major studies that compared DCD to donation after brain death liver transplantation, in terms of outcomes and complications. We also review the different methods of donor treatment that has been applied to ameliorate DCD organ outcome, and we discuss the role of machine perfusion techniques in organ reconditioning. We discuss the two major perfusionmodels, namely, hypothermic machine perfusion and normothermic machine perfusion; we compare both methods, and delineate their major differences.

A Cardiac Surgical Perspective on Hypothermia for Protection of Neural Tissues

Background: In clinical and basic science medicine, we often isolate ourselves in silos, unaware of developments in other related disciplines. Our team has had substantial experience, both in the operating room and in the laboratory, with protecting the brain and the spinal cord via hypothermia. Herein, we briefly share this experience with our colleagues in Neurology, eager for comments and advice from the neurologic perspective. Methods: 1) Clinical brain protection via deep hypothermic circulatory arrest (DHCA) for surgery of the aortic arch. For aortic arch replacement (performed for aortic arch aneurysm or aortic dissection), the aortic arch must be opened and native perfusion stopped. We have decades of experience in many hundreds of patients with this technique. This experience is reviewed. 2) Experimental protection of the spinal cord via cooling. We review our laboratory experience with a novel, recirculating cooling catheter for the vulnerable spinal cord. 3) Experimental protection of the brain via an intraventricular cooling catheter. We review our laboratory experience cooling the brain with a balloon-tipped catheter residing the lateral ventricles. Results: 1) Deep hypothermic circulatory arrest for aortic arch surgery provides superb brain protection for periods up to 45 minutes or longer. Clinical neurologic function, and quantitative neurologic tests, show excellent brain preservation. 2) The novel spinal cooling catheter provides excellent cooling of the spinal cord in a large animal model, without apparent injury of any type. 3) The intraventricular brain cooling catheter provides excellent cooling of the brain, documented by both direct temperature probe and high-tech brain imaging. Conclusions: We wish herein (in this article) to share this experience across our disciplines (Cardiac Surgery and Neurology). We welcome advice from the Neurology community on these surgically-directed methods for cooling and protection of neurological tissue in both the brain and the spinal cord.

Generation of Unfolded DNA in Human Neutrophils Following Hypothermal Treatment

By visualizing DNA with diamidino phenylindole (DAPI), we found that hypothermal incubation followed by rewarming of human neutrophils resulted in an increased number of DAPI-positive objects representative of extensive DNA unfolding seemingly similar to neutrophil extracellular traps (NETs). In contrast to canonical NET formation, diphenylene iodonium (DPI), an NADPH oxidase inhibitor, exhibited negligible effects on formation of the DAPI-positive objects. Moreover, multiple instances of DNA damage were detected in the objects, but not in canonical NETs. Our results thus suggest the potential of hypothermia for triggering DNA structural alteration in neutrophils, which is similar to but distinct from NET formation.

Application of biocompatible custom ceria nanoparticles in improving the quality of liver grafts for transplantation

Liver transplantation(LT),an ultimate and vital method for treating end-stage liver disease,is often accompanied by ischemiareperfusion injury(IRI)resulting from warm or cold ischemia of the donor liver.Organ protection techniques are used to improve the quality of liver grafts(from retrieval to implantation).Reactive oxygen species(ROS)cause oxidative stress,which is considered a crucial factor in IRI after LT.Nano antioxidants capable of scavenging ROS alleviate IRI in multiple types of organs and tissues.In this study,we synthesized ceria nanoparticles(NPs)with antioxidant properties using a pyrolysis method and covered them with phospholipid-polyethylene glycol to improve their biocompatibility in vivo.We investigated the potential organprotective effect of ceria NPs and the underlying mechanisms.Ceria NPs promoted liver function recovery after LT by attenuating IRI in liver grafts in vivo.The protective effect of ceria NPs on liver grafts was investigated by applying hypothermic oxygenated machine perfusion ex vivo.Ceria NPs attenuated hypoxia reoxygenation-or H_(2)O_(2)-induced hepatocyte injury by enhancing mitochondrial activity and ROS scavenging in vitro.These effects may be associated with the activation of the nuclear factor erythroid-derived 2-related factor 2(Nrf2)/Kelch-like ECH-associated protein 1(Keap1)/heme oxygenase 1(HO-1)signaling pathway.In conclusion,ceria NPs may serve as a promising antioxidant agent for the treatment of hepatic IRI after LT.

The conclusion of reducing acute rejection after liver transplantation by machine perfusion should be extrapolated with caution

There is a theory that the unavoidable graft damage caused by ischemia-reperfusion injury(IRI)during liver transplantation(LT)can lead to severe IRI-related inflammation and trigger an early activation of the innate immune response mediated by T-cells,which potentially worsening the acute cellular rejection(ACR)cascade.As a result,machine perfusion(MP)has been placed great expectations for the potential to diminish post-LT ACR and other related immune responses by alleviating IRI through removing harmful substances and restoring cellular metabolism homeostasis(1,2).However,there has been much debate about MP’s benefits on ACR as relative data is limited.