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Arnold M, Do P, Davidson SM, Large SR, Helmer A, Beer G, Siepe M, Longnus SL. Metabolic Considerations in Direct Procurement and Perfusion Protocols with DCD Heart Transplantation. Int J Mol Sci 2024; 25:4153. [PMID: 38673737 PMCID: PMC11050041 DOI: 10.3390/ijms25084153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
Heart transplantation with donation after circulatory death (DCD) provides excellent patient outcomes and increases donor heart availability. However, unlike conventional grafts obtained through donation after brain death, DCD cardiac grafts are not only exposed to warm, unprotected ischemia, but also to a potentially damaging pre-ischemic phase after withdrawal of life-sustaining therapy (WLST). In this review, we aim to bring together knowledge about changes in cardiac energy metabolism and its regulation that occur in DCD donors during WLST, circulatory arrest, and following the onset of warm ischemia. Acute metabolic, hemodynamic, and biochemical changes in the DCD donor expose hearts to high circulating catecholamines, hypoxia, and warm ischemia, all of which can negatively impact the heart. Further metabolic changes and cellular damage occur with reperfusion. The altered energy substrate availability prior to organ procurement likely plays an important role in graft quality and post-ischemic cardiac recovery. These aspects should, therefore, be considered in clinical protocols, as well as in pre-clinical DCD models. Notably, interventions prior to graft procurement are limited for ethical reasons in DCD donors; thus, it is important to understand these mechanisms to optimize conditions during initial reperfusion in concert with graft evaluation and re-evaluation for the purpose of tailoring and adjusting therapies and ensuring optimal graft quality for transplantation.
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Affiliation(s)
- Maria Arnold
- Department of Cardiac Surgery, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
| | - Peter Do
- Department of Cardiac Surgery, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
| | - Sean M. Davidson
- The Hatter Cardiovascular Institute, University College London, London WC1E 6HX, UK
| | - Stephen R. Large
- Royal Papworth Hospital, Biomedical Campus, Cambridge CB2 0AY, UK
| | - Anja Helmer
- Department of Cardiac Surgery, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Georgia Beer
- Department of Cardiac Surgery, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Matthias Siepe
- Department of Cardiac Surgery, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
| | - Sarah L. Longnus
- Department of Cardiac Surgery, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
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Arnold M, Segiser A, Graf S, Méndez-Carmona N, Sanz MN, Wyss RK, Kalbermatter N, Keller N, Carrel T, Longnus S. Pre-ischemic Lactate Levels Affect Post-ischemic Recovery in an Isolated Rat Heart Model of Donation After Circulatory Death (DCD). Front Cardiovasc Med 2021; 8:669205. [PMID: 34195235 PMCID: PMC8236508 DOI: 10.3389/fcvm.2021.669205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 05/12/2021] [Indexed: 11/23/2022] Open
Abstract
Introduction: Donation after circulatory death (DCD) could substantially improve donor heart availability. In DCD, the heart is not only exposed to a period of warm ischemia, but also to a damaging pre-ischemic phase. We hypothesized that the DCD-relevant pre-ischemic lactate levels negatively affect the post-ischemic functional and mitochondrial recovery in an isolated rat heart model of DCD. Methods: Isolated, working rat hearts underwent 28.5′ of global ischemia and 60′ of reperfusion. Prior to ischemia, hearts were perfused with one of three pre-ischemic lactate levels: no lactate (0 Lac), physiologic lactate (0.5 mM; 0.5 Lac), or DCD-relevant lactate (1 mM; 1 Lac). In a fourth group, an inhibitor of the mitochondrial calcium uniporter was added in reperfusion to 1 Lac hearts (1 Lac + Ru360). Results: During reperfusion, left ventricular work (heart rate-developed pressure product) was significantly greater in 0.5 Lac hearts compared to 0 Lac or 1 Lac. In 1 vs. 0.5 Lac hearts, in parallel with a decreased function, cellular and mitochondrial damage was greater, tissue calcium content tended to increase, while oxidative stress damage tended to decrease. The addition of Ru360 to 1 Lac hearts partially abrogated the negative effects of the DCD-relevant pre-ischemic lactate levels (greater post-ischemic left ventricular work and less cytochrome c release in 1 Lac+Ru360 vs. 1 Lac). Conclusion: DCD-relevant levels of pre-ischemic lactate (1 mM) reduce contractile, cellular, and mitochondrial recovery during reperfusion compared to physiologic lactate levels. Inhibition of mitochondrial calcium uptake during early reperfusion improves the post-ischemic recovery of 1 Lac hearts, indicating calcium overload as a potential therapeutic reperfusion target for DCD hearts.
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Affiliation(s)
- Maria Arnold
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Adrian Segiser
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Selianne Graf
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Natalia Méndez-Carmona
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Maria N Sanz
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Rahel K Wyss
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Nina Kalbermatter
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Nino Keller
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Thierry Carrel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Sarah Longnus
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
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Wyss RK, Méndez Carmona N, Arnold M, Segiser A, Mueller M, Dutkowski P, Carrel TP, Longnus SL. Hypothermic, oxygenated perfusion (HOPE) provides cardioprotection via succinate oxidation prior to normothermic perfusion in a rat model of donation after circulatory death (DCD). Am J Transplant 2021; 21:1003-1011. [PMID: 32786170 DOI: 10.1111/ajt.16258] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 01/25/2023]
Abstract
In donation after circulatory death (DCD), cardiac grafts are subjected to warm ischemia in situ, prior to a brief period of cold, static storage (CSS) at procurement, and ex situ, normothermic, machine perfusion (NMP) for transport and graft evaluation. Cold ischemia and normothermic reoxygenation during NMP could aggravate graft injury through continued accumulation and oxidation, respectively, of mitochondrial succinate, and the resultant oxidative stress. We hypothesized that replacing CSS with hypothermic, oxygenated perfusion (HOPE) could provide cardioprotection by reducing cardiac succinate levels before NMP. DCD was simulated in male Wistar rats. Following 21 minutes in situ ischemia, explanted hearts underwent 30 minutes hypothermic storage with 1 of the following: (1) CSS, (2) HOPE, (3) hypothermic deoxygenated perfusion (HNPE), or (4) HOPE + AA5 (succinate dehydrogenase inhibitor) followed by normothermic reperfusion to measure cardiac and metabolic recovery. After hypothermic storage, tissue ATP/ADP levels were higher and succinate concentration was lower in HOPE vs CSS, HNPE, and HOPE + AA5 hearts. After 60 minutes reperfusion, cardiac function was increased and cellular injury was decreased in HOPE compared with CSS, HNPE, and HOPE + AA5 hearts. HOPE provides improved cardioprotection via succinate oxidation prior to normothermic reperfusion compared with CSS, and therefore is a promising strategy for preservation of cardiac grafts obtained with DCD.
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Affiliation(s)
- Rahel K Wyss
- Department of Cardiovascular Surgery, Inselspital, University Hospital Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Natalia Méndez Carmona
- Department of Cardiovascular Surgery, Inselspital, University Hospital Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Maria Arnold
- Department of Cardiovascular Surgery, Inselspital, University Hospital Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Adrian Segiser
- Department of Cardiovascular Surgery, Inselspital, University Hospital Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Matteo Mueller
- Department of Surgery and Transplantation, University Hospital Zurich, Zurich, Switzerland
| | - Philipp Dutkowski
- Department of Surgery and Transplantation, University Hospital Zurich, Zurich, Switzerland
| | - Thierry P Carrel
- Department of Cardiovascular Surgery, Inselspital, University Hospital Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Sarah L Longnus
- Department of Cardiovascular Surgery, Inselspital, University Hospital Bern, Bern, Switzerland.,Department for BioMedical Research, University of Bern, Bern, Switzerland
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Arnold M, Méndez-Carmona N, Wyss RK, Joachimbauer A, Casoni D, Carrel T, Longnus S. Comparison of Experimental Rat Models in Donation After Circulatory Death (DCD): in-situ vs. ex-situ Ischemia. Front Cardiovasc Med 2021; 7:596883. [PMID: 33521061 PMCID: PMC7838125 DOI: 10.3389/fcvm.2020.596883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022] Open
Abstract
Introduction: Donation after circulatory death (DCD) could substantially improve donor heart availability. However, warm ischemia prior to procurement is of particular concern for cardiac graft quality. We describe a rat model of DCD with in-situ ischemia in order to characterize the physiologic changes during the withdrawal period before graft procurement, to determine effects of cardioplegic graft storage, and to evaluate the post-ischemic cardiac recovery in comparison with an established ex-situ ischemia model. Methods: Following general anesthesia in male, Wistar rats (404 ± 24 g, n = 25), withdrawal of life-sustaining therapy was simulated by diaphragm transection. Hearts underwent no ischemia or 27 min in-situ ischemia and were explanted. Ex situ, hearts were subjected to a cardioplegic flush and 15 min cold storage or not, and 60 min reperfusion. Cardiac recovery was determined and compared to published results of an entirely ex-situ ischemia model (n = 18). Results: In donors, hearts were subjected to hypoxia and hemodynamic changes, as well as increased levels of circulating catecholamines and free fatty acids prior to circulatory arrest. Post-ischemic contractile recovery was significantly lower in the in-situ ischemia model compared to the ex-situ model, and the addition of cardioplegic storage improved developed pressure-heart rate product, but not cardiac output. Conclusion: The in-situ model provides insight into conditions to which the heart is exposed before procurement. Compared to an entirely ex-situ ischemia model, hearts of the in-situ model demonstrated a lower post-ischemic functional recovery, potentially due to systemic changes prior to ischemia, which are partially abrogated by cardioplegic graft storage.
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Affiliation(s)
- Maria Arnold
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Natalia Méndez-Carmona
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Rahel K Wyss
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Anna Joachimbauer
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Daniela Casoni
- Experimental Surgery Facility (ESF), Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Thierry Carrel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Sarah Longnus
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
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Mechanical Postconditioning Promotes Glucose Metabolism and AMPK Activity in Parallel with Improved Post-Ischemic Recovery in an Isolated Rat Heart Model of Donation after Circulatory Death. Int J Mol Sci 2020; 21:ijms21030964. [PMID: 32024002 PMCID: PMC7039237 DOI: 10.3390/ijms21030964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 01/27/2020] [Accepted: 01/30/2020] [Indexed: 12/25/2022] Open
Abstract
Donation after circulatory death (DCD) could improve donor heart availability; however, warm ischemia-reperfusion injury raises concerns about graft quality. Mechanical postconditioning (MPC) may limit injury, but mechanisms remain incompletely characterized. Therefore, we investigated the roles of glucose metabolism and key signaling molecules in MPC using an isolated rat heart model of DCD. Hearts underwent 20 min perfusion, 30 min global ischemia, and 60 minu reperfusion with or without MPC (two cycles: 30 s reperfusion—30 s ischemia). Despite identical perfusion conditions, MPC either significantly decreased (low recovery = LoR; 32 ± 5%; p < 0.05), or increased (high recovery = HiR; 59 ± 7%; p < 0.05) the recovery of left ventricular work compared with no MPC (47 ± 9%). Glucose uptake and glycolysis were increased in HiR vs. LoR hearts (p < 0.05), but glucose oxidation was unchanged. Furthermore, in HiR vs. LoR hearts, phosphorylation of raptor, a downstream target of AMPK, increased (p < 0.05), cytochrome c release (p < 0.05) decreased, and TNFα content tended to decrease. Increased glucose uptake and glycolysis, lower mitochondrial damage, and a trend towards decreased pro-inflammatory cytokines occurred specifically in HiR vs. LoR MPC hearts, which may result from greater AMPK activation. Thus, we identify endogenous cellular mechanisms that occur specifically with cardioprotective MPC, which could be elicited in the development of effective reperfusion strategies for DCD cardiac grafts.
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Zoni E, Minoli M, Bovet C, Wehrhan A, Piscuoglio S, Ng CKY, Gray PC, Spahn M, Thalmann GN, Kruithof-de Julio M. Preoperative plasma fatty acid metabolites inform risk of prostate cancer progression and may be used for personalized patient stratification. BMC Cancer 2019; 19:1216. [PMID: 31842810 PMCID: PMC6916032 DOI: 10.1186/s12885-019-6418-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/29/2019] [Indexed: 02/06/2023] Open
Abstract
Background Little is known about the relationship between the metabolite profile of plasma from pre-operative prostate cancer (PCa) patients and the risk of PCa progression. In this study we investigated the association between pre-operative plasma metabolites and risk of biochemical-, local- and metastatic-recurrence, with the aim of improving patient stratification. Methods We conducted a case-control study within a cohort of PCa patients recruited between 1996 and 2015. The age-matched primary cases (n = 33) were stratified in low risk, high risk without progression and high risk with progression as defined by the National Comprehensive Cancer Network. These samples were compared to metastatic (n = 9) and healthy controls (n = 10). The pre-operative plasma from primary cases and the plasma from metastatic patients and controls were assessed with untargeted metabolomics by LC-MS. The association between risk of progression and metabolite abundance was calculated using multivariate Cox proportional-hazard regression and the relationship between metabolites and outcome was calculated using median cut-off normalized values of metabolite abundance by Log-Rank test using the Kaplan Meier method. Results Medium-chain acylcarnitines (C6-C12) were positively associated with the risk of PSA progression (p = 0.036, median cut-off) while long-chain acylcarnitines (C14-C16) were inversely associated with local (p = 0.034) and bone progression (p = 0.0033). In primary cases, medium-chain acylcarnitines were positively associated with suberic acid, which also correlated with the risk of PSA progression (p = 0.032, Log-Rank test). In the metastatic samples, this effect was consistent for hexanoylcarnitine, L.octanoylcarnitine and decanoylcarnitine. Medium-chain acylcarnitines and suberic acid displayed the same inverse association with tryptophan, while indoleacetic acid, a breakdown product of tryptophan metabolism was strongly associated with PSA (p = 0.0081, Log-Rank test) and lymph node progression (p = 0.025, Log-Rank test). These data were consistent with the increased expression of indoleamine 2,3 dioxygenase (IDO1) in metastatic versus primary samples (p = 0.014). Finally, functional experiments revealed a synergistic effect of long chain fatty acids in combination with dihydrotestosterone administration on the transcription of androgen responsive genes. Conclusions This study strengthens the emerging link between fatty acid metabolism and PCa progression and suggests that measuring levels of medium- and long-chain acylcarnitines in pre-operative patient plasma may provide a basis for improving patient stratification.
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Affiliation(s)
- Eugenio Zoni
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland
| | - Martina Minoli
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland
| | - Cédric Bovet
- University Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Anne Wehrhan
- University Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Salvatore Piscuoglio
- Institute of Pathology, University Hospital Basel, University of Basel, Basel, Switzerland.,Visceral Surgery Research Laboratory, Clarunis, Department of Biomedicine, University of Basel, Basel, Switzerland.,Clarunis Universitäres Bauchzentrum Basel, Basel, Switzerland
| | - Charlotte K Y Ng
- Visceral Surgery Research Laboratory, Clarunis, Department of Biomedicine, University of Basel, Basel, Switzerland.,Department for BioMedical Research, Oncogenomics, University of Bern, Bern, Switzerland
| | - Peter C Gray
- ScienceMedia Inc, 8910 University Center Ln Suite 400, San Diego, CA, 92122, USA
| | - Martin Spahn
- Zentrum für Urologie Zürich und Prostatakarzinomzentrum Hirslanden ZürichKlinik Hirslanden, Zürich, Switzerland.,Department of Urology, Essen University Hospital, University of Duisburg-Essen, Essen, Germany
| | - George N Thalmann
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland.,Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marianna Kruithof-de Julio
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland. .,Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
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7
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Differential effects of ischemia/reperfusion on endothelial function and contractility in donation after circulatory death. J Heart Lung Transplant 2019; 38:767-777. [DOI: 10.1016/j.healun.2019.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 02/21/2019] [Accepted: 03/08/2019] [Indexed: 01/18/2023] Open
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Farine E, Egle MU, Boone AC, Christensen S, Carrel TP, Tevaearai Stahel HT, Longnus SL. Development of a cardiac loading device to monitor cardiac function during ex vivo graft perfusion. PLoS One 2018; 13:e0195721. [PMID: 29702648 PMCID: PMC5922540 DOI: 10.1371/journal.pone.0195721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 03/28/2018] [Indexed: 11/18/2022] Open
Abstract
Background Ex vivo heart perfusion systems, allowing continuous perfusion of the coronary vasculature, have recently been introduced to limit ischemic time of donor hearts prior to transplantation. Hearts are, however, perfused in an unloaded manner (via the aorta) and therefore, cardiac contractile function cannot be reliably evaluated. Objectives We aim to develop a ventricular loading device that enables monitoring of myocardial function in an ex vivo perfusion system. In this initial study, was to develop a prototype for rat experimentation. Methods We designed a device consisting of a ventricular balloon and a reservoir balloon, connected through an electronic check valve, which opens and closes in coordination with changes in ventricular pressure. All balloons were produced in our laboratory and their properties, particularly pressure-volume relationships, were characterized. We developed a mock ventricle in vitro test system to evaluate the device, which was ultimately tested in ex vivo perfused rat hearts. Results Balloon production was consistent and balloon properties were maintained over time and with use on the device. Results from in vitro and ex vivo experiments show that the device functions appropriately; hemodynamic function can be measured and compares well to measurements made in an isolated, working (loaded) rat heart preparation. Conclusions Our cardiac loading device appears to reliably allow measurement of several left ventricular hemodynamic parameters and provides the opportunity to control ventricular load.
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Affiliation(s)
- Emilie Farine
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Manuel U. Egle
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Alice C. Boone
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Sandro Christensen
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Thierry P. Carrel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | | | - Sarah L. Longnus
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
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