Optimizing Resuscitation of the Donation after Circulatory Death Heart by Mitochondrial Protection in a Female Porcine Model.

BACKGROUND: Due to the shortage of donor organs, an increasing number of transplant organs are harvested after circulatory arrest (donation after circulatory death [DCD]). Using a translational porcine model of DCD, this study developed and evaluated a protocol based on cardioprotection by multidrug postconditioning to optimize resuscitation of DCD hearts during ex situ heart perfusion (ESHP). METHODS: Hearts of female pigs (45.0 ± 4.5 kg) were procured following a clinically identical DCD protocol, consisting of the termination of ventilator support and confirmation of circulatory arrest, followed by a 15-min standoff period. DCD hearts were randomly allocated to ESHP (38.4°C) in the absence (untreated, N = 5) or presence (treated, N = 5) of a postconditioning treatment added to the perfusate, consisting of Intralipid (1%), sevoflurane (2% v/v), and remifentanil (3 nM). All hearts were perfused with blood and Krebs-Henseleit solution (1:1) for 60 min in Langendorff mode and for an additional 300 min in working mode for a total perfusion time of 6 h. Oxidative capacity and detailed left ventricular mechanical function under an increasing workload (left atrial pressure, 6 to 12 mmHg) were assessed hourly. Left ventricular tissue was snap-frozen at the end of ESHP and used for molecular analyses. RESULTS: Left ventricular inotropy (LVdP/dtmax) did not decline over time in treated DCD hearts and was significantly higher at the end of the protocol as compared with untreated DCD hearts (ΔLVdP/dtmax = 440 mmHg/s; P = 0.009). Treated DCD hearts exhibited persistently higher left ventricular stroke work index during the 6-h period of ESHP, whereas untreated DCD hearts displayed a significant decline (change in left ventricular stroke work index = -3.10 ml · mmHg/g; P(time within untreated group) < 0.001). Treated DCD hearts displayed higher metabolic activity as measured by oxygen consumption (ΔO2 = 3.11 ml O2 · min-1 · 100 g-1; P = 0.004) and released lower amounts of cell-free mitochondrial DNA into the perfusate, a marker of potential graft dysfunction. Treated hearts also used fatty acids from Intralipid as an energy source, whereas untreated DCD hearts showed glyceroneogenesis with triglyceride accumulation and depletion of tricarboxylic acid cycle intermediates; reduced mitochondrial complex I, II, and III activities with accumulation of mitochondrial NADH, and signs of ultrastructural damage. CONCLUSIONS: A translationally relevant protective ESHP protocol consisting of treatment with Intralipid, sevoflurane, and remifentanil markedly accelerated functional recovery and improved viability of DCD hearts.

Relation of body mass index to long-term survival and cardiac remodelling for patients undergoing mitral valve replacement surgery.

BACKGROUND AND AIMS: Studies have demonstrated that obesity is paradoxically associated with reduced mortality following cardiac surgery. However, these studies have treated various types of cardiac surgery as a single entity. With mitral valve (MV) surgeries being the fastest-growing cardiac surgical interventions in North America, the purpose of this study was to identify the impact of body mass index (BMI) on long-term survival and cardiac remodelling of patients undergoing MV replacement (MVR). METHODS AND RESULTS: In this retrospective, single-center study, 1071 adult patients who underwent an MVR between 2004 and 2018 were stratified into five BMI groups (<20, 20-24.9, 25-29.9, 30-34.9, >35). Cox proportional hazard regression models were used to determine the association between BMI and all-cause mortality. Patients who were underweight had significantly higher all-cause mortality rates at the longest follow-up (median 8.2 years) than patients with normal weight (p = 0.01). Patients who were in the obese group had significantly higher readmission rates due to myocardial infarction (MI) at the longest follow-up (p = 0.017). Subgroup analysis revealed a significant increase in long-term all-cause mortality for female patients who were underweight. Significant changes in left atrial size, mitral valve peak and mean gradients were seen in all BMI groups. CONCLUSIONS: For patients undergoing mitral valve replacement, BMI is unrelated to operative outcomes except for patients who are underweight.

The Effects of Oxygen-Derived Free-Radical Scavengers During Normothermic Ex-Situ Heart Perfusion.

Oxidative stress occurs during ex-situ heart perfusion (ESHP) and may negatively affect functional preservation of the heart. We sought to assess the status of key antioxidant enzymes during ESHP, and the effects of augmenting these antioxidants on the attenuation of oxidative stress and improvement of myocardial and endothelial preservation in ESHP. Porcine hearts were perfused for 6 hours with oxygen-derived free-radical scavengers polyethylene glycol (PEG)-catalase or PEG-superoxide dismutase (SOD) or with naive perfusate (control). The oxidative stress-related modifications were determined in the myocardium and coronary vasculature, and contractile function, injury, and endothelial integrity were compared between the groups. The activity of key antioxidant enzymes decreased and adding catalase and SOD restored the enzyme activity. Cardiac function and endothelial integrity were preserved better with restored catalase activity. Catalase and SOD both decreased myocardial injury and catalase reduced ROS production and oxidative modification of proteins in the myocardium and coronary vasculature. The activity of antioxidant enzymes decrease in ESHP. Catalase may improve the preservation of cardiac function and endothelial integrity during ESHP. While catalase and SOD may both exert cardioprotective effects, unbalanced SOD and catalase activity may paradoxically increase the production of reactive species during ESHP.

First North American Experience with the Berlin Heart EXCOR® Active Driver.

For smaller pediatric patients on ventricular assist devices (VADs), the Berlin Heart EXCOR® remains the main form of durable support. It requires a connection to the external IKUS which has limited portability and battery life. The new EXCOR® Active mobile driving unit has battery life up to 13 hours. We describe the first North American experience with the EXCOR® Active in pediatric patients with a Berlin Heart device. Retrospective chart review was undertaken. Between Oct/2022 to Mar/2024, seven patients were on a Berlin Heart and supported with the EXCOR® Active. All patients were initially supported with the IKUS with a median time to transition to the EXCOR® Active of 12.0 days (IQR 9.5, 18.5) and a median time of support with the EXCOR® Active of 65.0 days (IQR, 32.0, 81.0). The EXCOR® Active posed no significant safety issues and minimal operating issues were noted. Following transition from IKUS to the EXCOR® Active there was increased patient and caregiver mobility throughout the hospital. Use of the EXCOR® Active has the potential to improve quality of life in pediatric patients waiting for heart transplantation.

Normothermic Perfusion is Superior to Cold Perfusion in Porcine Ex Situ Lung Perfusion.

BACKGROUND: Cold ex situ lung perfusion (ESLP) has demonstrated improved preservation in small animal ESLP compared to normothermic ESLP and cold static preservation. We hypothesized that cold negative pressure ventilation (NPV)-ESLP would improve graft function in a porcine transplantation model. METHODS: Four perfusate temperatures were examined with 12 hours NPV-ESLP in a large animal transplantation model. Pig lungs were allotted to four groups: (1) Normothermia (38°C, n = 6); (2) profound hypothermia (10°C, n = 6); (3) moderate hypothermia (20°C, n = 3); (4) subnormothermia (32°C, n = 3). A fifth group subnormothermic low-flow (SNLF) perfusion was examined to assess the effect of reduced cardiac output with cold perfusion (32°C, 10% cardiac output, n = 6). RESULTS: Only Normothermic and SNLF groups demonstrated acceptable oxygenation after 12 hours NPV-ESLP and were transplanted. All other groups failed prematurely. After 12 hours of ESLP, Normothermic lungs demonstrated significantly greater dynamic compliance compared to SNLF lungs (P = .03). Edema formation post-ESLP was significantly worse in the SNLF group (P = .01). There was no significant difference in pulmonary artery pressures after ESLP (P = .10); however, pulmonary vascular resistance was significantly greater in the SNLF (P = .04). Isolated left lung oxygenation 4-hours post-transplant and left lung edema formation was not significantly different between Normothermic and SNLF post-transplant (P = .09). Proinflammatory cytokines were significantly greater during SNLF-ESLP (tumor necrosis factor alpha, P < .05). CONCLUSIONS: Prolonged normothermic (38°C) NPV-ESLP is superior to 10, 20, and 32°C perfusion. Normothermic ESLP of porcine lungs results in superior graft function and reduced inflammation versus SNLF-ESLP.

Cyclosporine A Does Not Mitigate Liver Ischemia/Reperfusion Injury in an Ex Vivo Porcine Model of Donation After Circulatory Death.

BACKGROUND Ischemia/reperfusion injury (IRI) is an inherent problem in organ transplantation, owing to the obligate period of ischemia that organs must endure. Cyclosporine A (CsA), though better know as an immunosuppressant, has been shown to mitigate warm IRI in a variety of organ types, including the liver. However, there is little evidence for CsA in preventing hepatic IRI in the transplant setting. MATERIAL AND METHODS In the present study, we tested the effect of CsA on hepatic IRI in a large-animal ex vivo model of donation after circulatory death (DCD). Porcine donors were pre-treated with either normal saline control or 20 mg/kg of CsA. Animals were subject to either 45 or 60 minutes of warm ischemia before hepatectomy, followed by 2 or 4 hours of cold storage prior to reperfusion on an ex vivo circuit. Over the course of a 12-hour perfusion, perfusion parameters were recorded and perfusate samples and biopsies were taken at regular intervals. RESULTS Peak perfusate lactate dehydrogenase was significantly decreased in the lower-ischemia group treated with CsA compared to the untreated group (4220 U/L [3515-5815] vs 11 305 [10 100-11 674]; P=0.023). However, no difference was seen between controls and CsA-treated groups on other parameters in perfusate alanine or asparagine aminotransferase (P=0.912, 0.455, respectively). Correspondingly, we found no difference on midpoint histological injury score (P=0.271). CONCLUSIONS We found minimal evidence that CsA is protective against hepatic IRI in our DCD model.

Thoracic organ machine perfusion: A review of concepts with a focus on reconditioning therapies.

Thoracic organ transplantation, including lung, heart, and heart-lung transplants are highly regarded as gold standard treatments for patients suffering from heart failure or chronic end stage lung conditions. The relatively high prevalence of conditions necessitating thoracic organ transplants combined with the lack of available organs has resulted in many either dying or becoming too ill to receive a transplant while on the waiting list. There is a dire need to increase both the number of organs available and the utilization of such organs. Improved preservation techniques beyond static storage have shown great potential to lengthen the current period of viability of thoracic organs while outside the body, promising better utilization rates, increased donation distance, and improved matching of donors to recipients. Ex-situ organ perfusion (ESOP) can also make some novel therapeutic strategies viable, and the combination of the ESOP platform with such reconditioning therapies endeavors to better improve functional preservation of organs in addition to making more organs viable for transplantation. Given the abundance of clinical and pre-clinical studies surrounding reconditioning of thoracic organs in combination with ESOP, we summarize in this review important concepts and research regarding thoracic organ machine perfusion in combination with reconditioning therapies.

Impact of sex on long-term outcomes following mitral valve repair.

Introduction: Previous studies have identified inferior outcomes for women undergoing mitral valve (MV) surgery compared to men, although the cause of this discrepancy has not been identified. We look to isolate surgical approach to identify any impact that sex has on outcomes in order to better inform clinical decision making. Materials and methods: In this propensity matched, retrospective, single-center study, outcomes were compared between males and females undergoing a MV repair between 2004 and 2018. The primary outcome was defined as mortality at any point in the follow-up period. Secondary outcomes included stroke, myocardial infarction (MI), repeat revascularization, complications arising from the initial procedure, and postoperative cardiac remodeling. Results: A total of 188 males and 188 females were included after propensity matching. At a median follow up time of 7.6 years, there were 25 deaths in the male group (26.8%) and 23 in the female group (28.2%) (p = 0.771). There were no significant differences in MI, stroke, post-operative pacemaker insertion, or rehospitalization following MV repair. Left ventricular (LV) size for males was reduced from an initial 55.6 ± 7.3 mm to 49.9 ± 7.4 mm (p < 0.001), and for females from an initial 51.5 ± 7 mm to 46.9 ± 7.1 mm (p < 0.001). LV ejection fraction (LVEF) was reduced with a preoperative LVEF for males of 57.7% ± 8.9% and 53.7% ± 9.6% postoperatively (p = 0.002), and LVEF for females of 57.8% ± 9.1% preoperatively and 54.8% ± 9.2% postoperatively (p < 0.001). Left atrial (LA) volume was reduced from an initial 51 ± 22 ml/m2 to 43.7 ± 25.2 ml/m2 (p < 0.001), and 50.9 ± 19.2 ml/m2 to 44.2 ± 19.8 ml/m2 (p < 0.001), for males and females respectively. LA diameter was reduced for males from an initial 49.7 ± 9.7 mm to 47.3 ± 9.4 mm (p = 0.043), and from 48 ± 8.7 mm to 44.3 ± 9.1 mm for females postoperatively (p = 0.017). Conclusions: Current literature demonstrates inferior outcomes for females when compared to males undergoing MV surgery with patients undergoing a variety of surgical approaches. The results of this study suggest that surgical intervention for a subset of patients, those undergoing repair of the MV, is safe and offers similar outcomes for males and females.

Hypoxia Enhances the Therapeutic Potential of Superparamagnetic Iron Oxide-labeled Adipose-derived Stem Cells for Myocardial Infarction / 华中科技大学学报（医学）（英德文版）

Adipose-derived stem cells (ASCs) induce therapeutic angiogenesis due to pro-angiogenic cytokines secretion.Superparamagnetic iron oxide (SPIO) nanoparticles are critical for magnetic resonance (MR) tracking of implanted cells.Hypoxia is a powerful stimulus for angiogenic activity of ASCs.In this study,we investigated whether therapeutic potency could be enhanced by implantation of hypoxia-preconditioned SPIO-labeled ASCs (SPIOASCs) into the infarcted myocardium.ASCs and SPIOASCs were cultured under 2％ O2 (hypoxia) or 95％ air (normoxia).Cells were intramyocardially injected into the infarcted myocardium after 48-h culture.We found that hypoxia culture increased the mRNA expression of hypoxia-inducible factor-1 alpha (HIF-lαt) and vascular endothelial growth factor (VEGF) in ASCs and SPIOASCs.The VEGF protein in the conditioned medium was significantly higher in hypoxic ASCs and SPIOASCs than in normoxic ASCs and SPIOASCs.The capillary density and left ventricular contractile function in the infarcted myocardium were significantly higher 4 weeks after implantation with hypoxic ASCs and SPIOASCs than with normoxic ASCs and SPIOASCs.Improvement in the capillary density and left ventricle function didn't differ between hypoxic ASCs-transplanted rats and hypoxic SPIOASCs-transplanted rats.Hypoxic culture enhanced the angiogenic efficiency of ASCs.It was concluded that implantation of hypoxic ASCs or SPIOASCs promotes therapeutic angiogenesis and cardiac function recovery in the infarcted myocardium.SPIO labeling does not impact the beneficial effect of hypoxic ASCs.