Heart Preservation Research Articles

(752) - Ex-Vivo Heart Perfusion Using the Transmedics Organ Care System - A Single Center Experience

Single flush antegrade perfusion and cold storage is a simple and economic way for donor heart preservation. However, the ischemic tolerance is limited by cellular energy resources. Due to the increasing organ shortage an increasing number of marginal donor hearts with an increased risk of primary graft failure (PGF) is used. Ex-vivo perfusion using oxygenated warm blood perfusion of the heart during transport might offer a possible solution to increase the utility of donor organs and decrease the risk of PGF.

Hyperbranched polyglycerol as a colloid in cold organ preservation solutions.

Hydroxyethyl starch (HES) is a common colloid in organ preservation solutions, such as in University of Wisconsin (UW) solution, for preventing graft interstitial edema and cell swelling during cold preservation of donor organs. However, HES has undesirable characteristics, such as high viscosity, causing kidney injury and aggregation of erythrocytes. Hyperbranched polyglycerol (HPG) is a branched compact polymer that has low intrinsic viscosity. This study investigated HPG (MW-0.5 to 119 kDa) as a potential alternative to HES for cold organ preservation. HPG was synthesized by ring-opening multibranching polymerization of glycidol. Both rat myocardiocytes and human endothelial cells were used as an in vitro model, and heart transplantation in mice as an in vivo model. Tissue damage or cell death was determined by both biochemical and histological analysis. HPG polymers were more compact with relatively low polydispersity index than HES in UW solution. Cold preservation of mouse hearts ex vivo in HPG solutions reduced organ damage in comparison to those in HES-based UW solution. Both size and concentration of HPGs contributed to the protection of the donor organs; 1 kDa HPG at 3 wt% solution was superior to HES-based UW solution and other HPGs. Heart transplants preserved with HPG solution (1 kDa, 3%) as compared with those with UW solution had a better functional recovery, less tissue injury and neutrophil infiltration in syngeneic recipients, and survived longer in allogeneic recipients. In cultured myocardiocytes or endothelial cells, significantly more cells survived after cold preservation with the HPG solution than those with the UW solution, which was positively correlated with the maintenance of intracellular adenosine triphosphate and cell membrane fluidity. In conclusion, HPG solution significantly enhanced the protection of hearts or cells during cold storage, suggesting that HPG is a promising colloid for the cold storage of donor organs and cells in transplantation.

Twelve Hour Hypothermic Machine Perfusion for Donor Heart Preservation Leads to Improved Ultrastructural Characteristics Compared to Conventional Cold Storage

Objectives: Hypothermic machine perfusion of donor hearts enables continuous aerobic metabolism and washout of toxic metabolic byproducts. We evaluated the effect of machine perfusion on cardiac myocyte integrity in hearts preserved for 12 hours in a novel device that provides pulsatile oxygenated hypothermic perfusion (Paragonix Sherpa Perfusion™ Cardiac Transport System).

Twelve-Hour Hypothermic Machine Perfusion for Donor Heart Preservation Leads to Improved Ultrastructural Characteristics Compared to Conventional Cold Storage.

BACKGROUND Hypothermic machine perfusion of donor hearts has the theoretical advantage of continuous aerobic metabolism and washes out toxic metabolic byproducts. Here, we studied the effect of hypothermic machine perfusion on cardiac myocyte integrity when hearts are preserved for longer ischemic times (12 hours). MATERIAL AND METHODS Pig hearts were harvested and stored in Celsior® solution for 12 hours using either conventional cold storage on ice (12 h CS, n=3) or pulsatile perfusion with the Paragonix Sherpa Perfusion™ Cardiac Transport System at different flow rates (12 h PP, n=3 or 12 h PP low flow, n=2). After cold preservation, hearts were reperfused using an LV isovolumic Langendorff system. Controls (n=3) were reperfused immediately after organ harvest. Biopsies were taken from the apex of the left ventricle before storage, after storage and after reperfusion to measure ATP and endothelin-1 content in the tissue. TUNEL staining for signs of apoptosis and electron microscopy of the donor hearts were performed. RESULTS 12 h PP hearts showed significantly more weight gain than 12 h CS and controls after preservation. Pulsatile perfused hearts showed less ATP depletion, lower endothelin-1 levels and less apoptosis after preservation compared to CS. Electron microscopy showed damaged muscle fibers, endothelial cell rupture, and injury of mitochondria in the 12 h CS group, while machine perfusion could preserve the cell structures. CONCLUSIONS Hypothermic machine perfusion of donor hearts can preserve the cell structures better than conventional cold storage in prolonged ischemic times. Hypothermic pulsatile perfusion may therefore enable longer preservation times of donor hearts. Whether this method is able to avoid primary graft failure after orthotopic heart transplantation remains to be evaluated in further studies.

Preservation of the donor heart: from basic science to clinical studies

The methods of donor heart preservation are aimed at minimizing graft dysfunction caused by ischaemia-reperfusion injury (IRI) which inevitably occurs during the ex vivo transport interval. At present, the standard technique of heart preservation is cardiac arrest followed by static cold storage in a crystalloid heart preservation solution (HPS). This technique ensures an acceptable level of heart protection against IRI for <6 h. In clinical trials, comparable levels of myocardial protection against IRI were provided by various HPSs. The growing shortage of donor hearts is one of the major factors stimulating the development of new techniques of heart preservation. Here, we summarize new HPS formulations and provide a focus for optimization of the composition of existing HPSs. Such methods of donor heart preservation as machine perfusion, preservation at sub-zero temperature and oxygen persufflation are also discussed. Furthermore, we review experimental data showing that pre- and post-conditioning of the cardiac graft can improve its function when used in combination with cold storage. The evidence on the feasibility of cardiac donation after circulatory death, as well as the techniques of heart reconditioning after a period of warm ischaemia, is presented. The implementation of new techniques of donor heart preservation may contribute to the use of hearts from extended criteria donors, thereby expanding the total donor pool.

DNA/RNA Degradation Rate in Long Term Fixed Museum Specimens

In today’s research driven society, it has become commonplace for institutions to rely upon DNA and RNA extraction techniques to help obtain genomic data from old specimens. Generally, specimens are preserved for future gross examination and/or teaching. Using histological examination of specimens from museum jars from the Pathology Department at the Indiana University School of Medicine, the sequential and chronological degradation of DNA and RNA has been studied. We examined gross specimens from 1920 to 2000. We evaluated histologic preservation of kidney, liver, heart, lung, spleen, uterus and brain for nuclear structure in these samples. Nuclear preservation was based on amount of nuclei per microscopic field and the crispness of the nuclear membrane and internal features. The nuclei in high lipid tissues such as the brain were found to degrade at a quicker rate than dense tissues such as the heart and uterus. Our study has shown that specimens preserved beyond fifty years were likely to have little to no nuclei left, thus indicating that there was little to no DNA and RNA remaining. This technique of histologic evaluation is an important finding and a general guideline which may save research institutions from the expensive process of DNA and RNA extraction.

Low-Flow Hypothermic Crystalloid Perfusion Is Superior to Cold Storage During Prolonged Heart Preservation

BackgroundPreservation of donor hearts for transplantation has traditionally been performed with the use of static cold storage. We have developed and tested a novel gravity-powered system of cold crystalloid perfusion for prolonged donor heart preservation. MethodsGreyhounds were anesthetized; their hearts were arrested with cold cardioplegic solution and excised. Hearts were allocated to 12 hours of perfusion preservation (n = 6) or cold storage in ice (n = 5). Non-preserved hearts (n = 5) served as a normal reference group. Perfusion hearts were perfused (20 mL/min, 8–12°C) with a novel oxygenated nutrient-containing preservation solution. After preservation, the recovery of the hearts was assessed in a blood-perfused working heart rig over 2 hours in terms of function, blood lactate level, myocardial adenosine triphosphate, and histology. ResultsAfter 2 hours of reperfusion, in comparison with cold storage hearts, perfused heart function curves showed superior recovery of cardiac output (P = .001), power (P = .001), and efficiency (0.046 ± 0.01 vs 0.004 ± 0.003 joules/mL O2, P = .034). Myocardial adenosine triphosphate content (mmol/mg protein) was reduced significantly from the normal level of 26.5 (15.9, 55.8) to 5.08 (0.50, 10.4) (P = .049) in cold storage hearts but not in perfused hearts. Over a period of 2 hours, lactate levels in the blood perfusate were significantly lower in the perfusion group than in the cold storage group (P < .05). ConclusionsContinuous hypothermic crystalloid perfusion provides myocardial preservation superior to cold storage for long-term heart preservation, with potential applicability to marginal and donation after circulatory death hearts.

Heart Donation After Cardiac Death: Preliminary Study on an Isolated, Perfused Swine Heart After 20 Minutes of Normothermic Ischemia

BackgroundWe measured the functional and metabolic status of hearts submitted to normothermic ischemia before preservation through the use of an ex vivo pig heart model to assess the feasibility of donation after cardiac death (DCD) in heart transplantation. MethodsTen pigs were separated into 2 groups: control (n = 6, brain-dead group) and DCD (n = 4, heart donation after cardiac death). In the control group, hearts were excised 20 minutes after the brachiocephalic trunk cross-clamping and were immediately reperfused. In DCD, hearts were excised 20 minutes after exsanguination and asphyxia, stored in the Centre de Résonance Magnétique Biologique et Médicale (CRMBM) solution for 2 hours, and then were reperfused. Cardioplegic arrest was induced with the use of 1 L of CRMBM solution (4°C) and the heart was reperfused for 60 minutes through the use of an ex vivo perfusion system in Langendorff mode with normothermic autologous blood. During reperfusion, functional parameters were analyzed. Biochemical assays were performed in myocardial effluents and freeze-clamped hearts. ResultsNo electromechanical activity was found in DCD compared with control. Creatine kinase (CK) was higher at 2 minutes of reperfusion in DCD versus control (P = .005). Adenosine triphosphate was lower in DCD versus control (P = .0019). Malondialdehyde, an oxidative stress index, was present only in DCD. The nitric oxide (NO) pathway was impaired in DCD versus control, with lower eNOS expression (P < .0001) and total nitrate concentration content (P = .04). ConclusionsWe reported no cardiac functional and metabolic recovery in the DCD group after normothermic ischemia and reperfusion, which indicates that a single immersion of the cardiac graft during storage does not provide an optimal protection. New strategies in heart preservation are necessary for recruiting heart donation after cardiac death.

Evaluation of the Organ Care System in Heart Transplantation With an Adverse Donor/Recipient Profile

A severe shortage of available donor organs has created an impetus to use extended criteria organs for heart transplantation. Although such attempts increase donor organ availability, they may result in an adverse donor-recipient risk profile. The TransMedics Organ Care System (OCS) (TransMedics, Inc, Boston) allows preservation of the donor heart by perfusing the organ at 34°C in a beating state, potentially reducing the detrimental effect of cold storage and providing additional assessment options. We describe a single-center experience with the OCS in high-risk heart transplant procedures. Thirty hearts were preserved using the OCS between February 2013 and January 2014, 26 of which (86.7%) were transplanted. Procedures were classified as high risk based on (1) donor factors, ie, transport time more than 2.5 hours with estimated ischemic time longer than 4 hours, left ventricular ejection fraction (LVEF) less than 50%, left ventricular hypertrophy (LVH), donor cardiac arrest, alcohol/drug abuse, coronary artery disease or (2) recipient factors, ie, mechanical circulatory support or elevated pulmonary vascular resistance (PVR), or both. Donor and recipient age was 37 ± 12 years and43 ± 13 years, respectively. Allograft cold ischemia time was 85 ± 17 minutes and OCS perfusion time was 284 ± 90 minutes. The median intensive care unit stay was6 days. One death (3.8%) was observed over the follow-up: 257 ± 116 (109-445 days). There was preserved allograft function in 92% of patients, with a mean LVEF of 64% ± 5%. Use of the OCS is associated with markedly improved short-term outcomes and transplant activity by allowing use of organs previously not considered suitable for transplantation or selection of higher risk recipients, or both.

Characterizing Cardiac Donation After Circulatory Death: Implications for Perfusion Preservation

Donation after circulatory determination of death (DCDD) involves variable definitions of death among hospitals, and DCDD hearts are not generally considered for transplantation. The definition can affect ischemic times, and machine perfusion preservation appears promising for recovery of DCDD hearts. The purpose of the current study was to investigate the agonal phase of DCDD donors and evaluate retrograde perfusion preservation of DCDD donor hearts in a large animal model of cardiac transplantation. Ten canines were anesthetized and then disconnected from mechanical ventilation. Time to loss of pulse (systolic blood pressure <50 mm Hg), loss of pressure, and asystole or fibrillation were recorded. Five minutes after asystole, hearts were exposed and arrested with 1 L of University of Wisconsin Machine Perfusion Solution. Eight hearts were cold preserved for 4 hours by retrograde machine perfusion or static storage (n= 4/group), then reimplanted and reperfused for 6 hours. Thepreload recruitable stroke work was used to measure myocardial function. The agonal phase was similar between groups. Loss of pulse and pressure were consistent between animals (7.9 ± 0.5 minutes [range, 5 to 11 minutes], 10.2 ± 0.4 minutes [range, 9 to 13 minutes], respectively). Electrical silence wasvariable at 26.9 ± 3.8 minutes (range, 11 to 43 minutes). All perfused hearts separated and remained off cardiopulmonary bypass. Three of four static hearts initially separated from cardiopulmonary bypass, but two returned by the end of the reperfusion period. The preload recruitable stroke work was significantly higher in perfused hearts. Protocols for DCDD have implications on ischemic times of donor hearts. Machine perfusion preservation can recover DCDD hearts more consistently than static storage.

Cardio-protective Signalling by Glyceryl Trinitrate and Cariporide in a Model of Donor Heart Preservation

Storage of donor hearts in cardioplegic solutions supplemented with agents that mimic the ischaemic preconditioning response enhanced their post-reperfusion function. The present study examines the minimisation of cell death and activation of pro-survival signalling directed towards maintenance of mitochondrial homeostasis in hearts arrested and stored in two such agents, glyceryl-trinitrate, a nitric oxide donor and cariporide, (a sodium-hydrogen exchange inhibitor). After baseline functional measurement, isolated working rat hearts were arrested and stored for 6h at 4°C in either Celsior(®), Celsior(®) containing 0.1mg/ml glyceryl-trinitrate, 10μM cariporide or both agents. After reperfusion, function was remeasured. Hearts were then processed for immunoblotting or histology. Necrotic and apoptotic markers present in the Celsior(®) group post-reperfusion were abolished by glyceryl-trinitrate, cariporide or both. Increased phosphorylation of ERK and Bcl2, after reperfusion in groups stored in glyceryl-trinitrate, cariporide or both along with increased phospho-STAT3 levels in the glyceryl-trinitrate/cariporide group correlated with functional recovery. Inhibition of STAT3 phosphorylation blocked recovery. No phospho-Akt increase was seen in any treatment. Activation of signalling pathways that favour mitophagy activation (ERK and Bcl2 phosphorylation) and maintenance of mitochondrial transition pore closure after reperfusion (STAT3 and ERK phosphorylation) were crucial for functional recovery of the donor heart.

Primary Graft Dysfunction After Heart Transplantation

Primary graft dysfunction (PGD) is a life-threatening complication of heart transplantation that presents as left, right, or biventricular dysfunction occurring within the first 24 hours of transplant surgery for which there is no identifiable secondary cause. Myocardial injury caused by acute catecholamine toxicity and the release of multiple proinflammatory mediators in the donor, followed by ischaemia-reperfusion injury sustained during retrieval, have been considered the predominant pathogenetic processes leading to PGD. Donor, recipient, and procedural factors contribute to the development and severity of the clinical syndrome. The changing donor and recipient characteristics over the last two decades, particularly the increasing donor and recipient age, have led to heightened risk of PGD. PGD is graded from mild to severe depending on the extent of circulatory support that is required to maintain haemodynamic stability and vital organ function. While advances in acute mechanical support devices have improved the outlook for patients with PGD, the rate of mortality remains high for those with severe PGD, reaching 40 %. Potential approaches to preventing or minimising the severity of PGD include optimising donor management, donor heart preservation, and donor/recipient matching.

Normothermic donor heart perfusion: current clinical experience and the future.

Following the first successful heart transplant in 1967, more than 100,000 heart transplants have been carried out worldwide. These procedures have mostly relied on cold ischaemic preservation of the donor heart because this simple technique is inexpensive and relatively reliable. However, the well-known limitations of cold ischaemic preservation imposes significant logistical challenges to heart transplantation which put a ceiling on the immediate success on this life-saving therapy, and limits the number of donor hearts that can be safely transplanted annually. Although the theoretical advantages of normothermic donor heart perfusion have been recognised for over a century, the technology to transport donor hearts in this state has only been developed within the last decade. The Organ Care System (OCS) which is designed and manufactured by TransMedics Inc. is currently the only commercially available device with this capability. This article reviews the history of normothermic heart perfusion and the clinical experience with the TransMedics OCS to date. We have also attempted to speculate on the future possibilities of this innovative and exciting technology.

Superior Donor Heart Preservation Using Hypothermic Oxygenated Perfusion.

Purpose Hypothermic machine perfusion of donor hearts enables continuous aerobic metabolism and washout of toxic metabolic byproducts. We evaluated the effect of machine perfusion on cardiac myocyte integrity in hearts preserved for 4 hours in a novel device that provides pulsatile oxygenated hypothermic perfusion (Paragonix Sherpa PerfusionTM Cardiac Transport System). Methods All pig hearts were perfused with 1L of cold Celsior® solution after aortic cross-clamping, and then harvested. They were stored conventionally in Celsior® solution on ice for 4 hours (Celsior® storage [CS], n=6) or placed in the Sherpa device for 4 hours (pulsatile perfusion [PP], n=6). After cold preservation, hearts were evaluated hemodynamically using a Langendorff system. Systolic function was measured by +dP/dt; and diastolic function was measured by -dP/dt and EDP. Three control swine hearts were also re-perfused and evaluated immediately after harvest on the Langendorff system. Biopsies were taken from the LV apex at the time of harvest, after storage (when relevant), and after reperfusion for ultra-structural analysis using electron microscopy. Results CS, PP, and control hearts did not show any significant differences in systolic or diastolic function (+dP/dt, -dP/dt, EDP). CS hearts had more arrhythmias (supraventricular and ventricular) compared to PP and control hearts. Electron microscopy revealed endothelial cell rupture and damaged muscle fibers in the CS group after reperfusion, while the cell structures were preserved in the PP group and the control group. After preservation, PP hearts showed mild edema, which was not present in CS hearts, but after reperfusion, both groups had a similar grade of interstitial edema. Conclusions Hypothermic pulsatile perfusion of donor hearts during the storage interval is a simple technique that leads to better preservation of cell structure, as compared to a conventional cold storage method. This may lead to less risk of primary graft failure after orthotopic heart transplantation. Donor hearts preserved with pulsatile perfusion also appear less prone to arrhythmias during the reperfusion period. DISCLOSURES:Anderson, L.: Other, Paragonix Technologies, President. Madsen, J.: Grant/Research Support, Paragonix Technologies.

A Novel Hyperbranched Polyglycerol-Based Solution for Donor Organ Preservation: A Comparison With University of Wisconsin Solution in Hypothermic Preservation of Mouse Donor Hearts.

A Novel Hyperbranched Polyglycerol-Based Solution for Donor Organ Preservation: A Comparison With University of Wisconsin Solution in Hypothermic Preservation of Mouse Donor Hearts.

Sub-normothermic preservation of donor hearts for transplantation using a novel solution, Somah: A comparative pre-clinical study

Hearts preserved ex vivo at extreme hypothermia (4°C) undergo time-dependent irreversible injury. Our studies using a novel solution, Somah, suggest that hearts are viably preserved at 21°C. In this study we evaluate the relative efficacy of Somah for preservation of hearts at 21°C when compared with the clinically used Celsior and University of Wisconsin (UWS) solutions. Porcine hearts arrested by cardioplegia at 21°C using Somah, Celsior or UWS solution were stored in the respective solutions at 21°C (n = 5) for 5 hours and then reperfused ex vivo for functional assessment. We assessed development of edema, cardiac tissue high-energy phosphate (HEP; ATP + creatine phosphate) levels and release of cardiac enzymes. Alterations in left ventricular wall thicknesses and functional parameters were examined by 2-dimensional (2D) echocardiography. Changes in myocardial oxygen consumption (MVO2) and lactate utilization were assessed at reperfusion. Heart weights were unaltered during 5-hour storage in all groups. After storage, HEP levels were 28.33 ± 5.51, 10.20 ± 2.78 and 5.92 ± 1.46 nmol/liter per milligram protein (p < 0.001) in the Somah, Celsior and UWS group hearts, respectively. Upon reanimation, 2D echocardiography showed edema in the Celsior and UWS hearts; prompt attainment of physiologic function was associated with rapid establishment of aerobic metabolism not requiring stimulatory interventions in the Somah hearts, but not in the Celsior/UWS hearts. Percent fractional area change, ejection fraction and stroke volume were significantly higher (p < 0.001) in Somah hearts than in Celsior and UWS group hearts. Increased synthesis of HEP, rapid metabolic switch and optimal function together provide evidence that hearts procured for transplantation are preserved in a superior viable condition at 21°C with Somah, but not with other commonly used clinical preservation solutions.

Extracorporeal Membrane Oxygenation Support in Acardia

In extreme situations, such as hyperacute rejection of heart transplant or major heart trauma, heart preservation may not be possible. Our experimental team works on a project of peripheral extracorporeal membrane oxygenation (ECMO) support in acardia as a bridge to heart transplantation or artificial heart implantation. An ECMO support was established in five calves (58.6 ± 6.9 kg) by the transjugular insertion to the caval axis of a self-expanded cannula, with carotid artery return. After baseline measurements, ventricular fibrillation was induced, great arteries were clamped, heart was excised, and right and left atria remnants, containing pulmonary veins, were sutured together leaving an atrial septal defect over the caval axis cannula. Measurements of pump flow and arterial pressure were taken with the pulmonary artery clamped and anastomosed with the caval axis for a total of 6 hours. Pulmonary artery anastomosis to the caval axis provided an acceptable 6 hour hemodynamic stability, permitting a peripheral access ECMO support in extreme scenarios indicating a heart explantation.

Myocardial Protection in Donor Heart Preservation: A Comparison Between Bretschneider's Histidine–Tryptophan–Ketoglutarate Solution and Cold Blood Cardioplegia

BackgroundOptimal myocardial protection for donated hearts is crucial to improve outcomes of heart transplantation and reduce morbidity and mortality. This study aimed to compare the efficacy of myocardial protection using single dose of Bretschneider's histidine–tryptophan–ketoglutarate (HTK) solution and repeated doses of cold blood cardioplegia (CBC) in donor heart preservation. MethodsSixty-seven patients undergoing heart transplantation in Tri-Service General Hospital, Taipei, Taiwan between 2002 and 2012 were enrolled in this study. Patients were divided into an HTK group and a CBC group based on the preservation solution used to protect the donated hearts. The perioperative variables and postoperative outcomes were retrospectively reviewed. ResultsThere were no statistic differences about demographic data in donors and recipients between the 2 groups. There were no significant differences in postoperative cardiac enzymes, hemodynamic data, length of stay in intensive care, or 30-day mortality between the groups. The HTK group showed a trend of shorter pumping time (P = .091). Multivariate analyses reveal that the HTK group had higher postoperative inotropic score (P < .001) and shorter pumping time (P = .02). ConclusionsSingle dose of Bretschneider's HTK solution could effectively reduce pumping time and afford similar myocardial protection compared with repeated doses of CBC in the preservation of donated hearts.

Metabolic characteristics of human hearts preserved for 12 hours by static storage, antegrade perfusion, or retrograde coronary sinus perfusion

Machine perfusion of donor hearts is a promising strategy to increase the donor pool. Antegrade perfusion is effective but can lead to aortic valve incompetence and nonnutrient flow. Experience with retrograde coronary sinus perfusion of donor hearts has been limited. We tested the hypothesis that retrograde perfusion could support myocardial metabolism over an extended donor ischemic interval. Human hearts from donors that were rejected or not offered for transplantation were preserved for 12 hours in University of Wisconsin Machine Perfusion Solution by: (1) static hypothermic storage; (2) hypothermic antegrade machine perfusion; or (3) hypothermic retrograde machine perfusion. Myocardial oxygen consumption (MVO2), and lactate accumulation were measured. Ventricular tissue was collected for proton and phosphorus 31 magnetic resonance spectroscopy (MRS) to evaluate the metabolic state of the myocardium. Myocardial water content was determined at the end of the experiment. Stable perfusion parameters were maintained throughout the perfusion period with both perfusion techniques. Lactate/alanine ratios were lower in perfused hearts compared with static hearts (P<.001). Lactate accumulation (antegrade 2.0±0.7 mM, retrograde 1.7±0.1 mM) and MVO2 (antegrade 0.25±0.2 mL, retrograde 0.26±0.3 mL O2/min/100 g) were similar in machine-perfused groups. High-energy phosphates were better preserved in both perfused groups (P<.05). Left ventricular myocardial water content was increased in retrograde perfused hearts (80.2±0.8%) compared with both antegrade perfused hearts (76.6±0.8%, P=.02) and static storage hearts (76.7±1%, P=.02). Machine perfusion by either the antegrade or the retrograde technique can support myocardial metabolism over long intervals. Machine perfusion seems promising for long-term preservation of human donor hearts.

Improvement of Functional Recovery of Donor Heart Following Cold Static Storage with Doxycycline Cardioplegia

Injury to the donor heart during cold preservation has a negative impact on graft survival before transplantation. This study aims to examine whether doxycycline, known as an MMP-2 inhibitor, has a positive effect on donor heart preservation via its antioxidant action when added to standard preservation solution. Hearts were obtained from 3-month-old male Wistar rats and randomly divided into three groups: hearts stored for 1 h at 4 °C (1) with doxycycline preservation solution (DOX cardioplegia) with low Ca2+; (2) with standard cardioplegia with low Ca2+; and (3) unstored hearts. All hearts were perfused in working mode, arrested at 37 °C, removed from the perfusion system, reattached in Langendorff perfusion system, and converted to working mode for 1 h. At the end of the storage period, hearts preserved in DOX cardioplegia had significantly less weight gain than those preserved in the standard cardioplegia. DOX cardioplegia-induced preservation resulted in significantly higher heart rates and better recovery quality during reperfusion in aortic flow compared to the standard cardioplegia group. Recovery in the left ventricular function and Lambeth Convention Arrhythmia scores during 1 h reperfusion were also significantly better in the DOX cardioplegia group. Biochemical data showed that DOX cardioplegia prevented an increase in MMP-2 activity and blocked apoptosis through increased activity of the pro-survival kinase Akt in the donor heart homogenates. DOX cardioplegia also led to a balanced oxidant/antioxidant level in the heart homogenates. This is the first study to report that cardioplegia solution containing doxycycline provides better cardioprotection via the preservation of heart function, through its role in controlling cellular redox status during static cold storage.