Apoptotic Markers in Donor Hearts After Brain Death vs Circulatory Death.

BACKGROUND: Use of donation after circulatory death (DCD) hearts is becoming more prevalent in cardiac transplantation. However, there is no standardized approach to myocardial preservation, and little data exists on ultrastructural changes in DCD hearts. We have previously identified increased proapoptotic and proinflammatory activity in brain dead donor (BDD) hearts that subsequently exhibit primary graft failure and lower levels in DCD left atrial tissue. This study further investigates these markers and correlates them with cardiac function in DCD hearts. METHODS: This prospective study used donor hearts deemed unsuitable for transplant after gaining institutional ethics approval; 11 human hearts were obtained from 5 DCD donors and 6 BDDs. All hearts were preserved by continuous microperfusion for 4 hours with a cold crystalloid solution and then were evaluated on a blood perfusion bench rig. After 4 hours perfusion and working assessment, tissues from all cardiac chambers were stored for later messenger RNA (mRNA) analysis for proapoptotic and proinflammatory markers. RESULTS: Significantly raised levels of caspase-1, BNIP3, and NADPH oxidase mRNA expression were identified in cardiac chambers from BDD hearts compared to DCD hearts, and these differences were exaggerated in older donors. In the pooled analysis, lower expression of caspase-1, NF-κB1, and BNIP3 mRNA correlated with developed pressure at 1 hour after reperfusion in the right ventricle, but not the left. CONCLUSION: Compared to BDD hearts, DCD hearts exhibit less stimulation of proapoptotic cascades and reactive oxygen species, potentially reducing their susceptibility to ischemic reperfusion injury.

Combined Assessment of Functional and Metabolic Performance of Human Donor Hearts: Possible Application in Donation After Circulatory Death.

BACKGROUND: Donation after circulatory death (DCD) represents an increasing source of organs. However, evaluating the suitability of DCD hearts for transplantation represents a challenge. Contractile function is the ultimate determinant of recovery. We developed a novel technique in an ex vivo rig for the measurement of contractility using intraventricular balloons. We compared this technique with the measurement of lactate metabolism, the current gold standard. METHODS: Human DCD (n = 6) and donation after brain death (n = 6) hearts were preserved by perfusion with a cold oxygenated crystalloid solution for 4 h, transferred to a blood perfusion rig at 37 °C where balloons were inserted into the left (LV) and right (RV) ventricles to measure developed pressure (DP = systolic minus diastolic). Perfusate lactate levels were measured for metabolic assessment. Concordance between LVDP and lactate was assessed during 4 h using cutoffs for LVDP of 70 mm Hg and for lactate of 10 mmol/L. RESULTS: Measurements of contractile function (LVDP) and metabolism (lactate levels) were deemed concordant in 7 hearts with either a high LVDP (mean 100 mm Hg) with low lactate (mean 6.7 mmol/L)) or a low LVDP (15 mm Hg) with high lactate (mean 17.3 mmol/). In the remaining 5 hearts, measurements were deemed discordant: 4 hearts had high LVDP (mean 124 mm Hg), despite high lactate levels 17.3 mmol/L) and 1 had low LVDP (54 mm Hg) but low lactate (6.9 mmol/L). CONCLUSIONS: The intraventricular balloon technique provides useful information regarding contractile recovery of donor hearts that if combined with lactate metabolism has potential application for the evaluation of DCD and marginal donation after brain death hearts before transplant.

CoQ10 and Cognition a Review and Study Protocol for a 90-Day Randomized Controlled Trial Investigating the Cognitive Effects of Ubiquinol in the Healthy Elderly.

Introduction: With an aging population there is an important need for the development of effective treatments for the amelioration of cognitive decline. Multiple mechanisms underlie age-related cognitive decline including cerebrovascular disease, oxidative stress, reduced antioxidant capacity and mitochondrial dysfunction. CoQ10 is a novel treatment which has the potential to improve brain function in healthy elderly populations due to established beneficial effects on mitochondrial function, vascular function and oxidative stress. Methods and Analysis: We describe the protocol for a 90-day randomized controlled trial which examines the efficacy of Ubiquinol (200 mg/day) vs. placebo for the amelioration of cognitive decline in a healthy (non-demented) elderly sample, aged 60 years and over. The primary outcome is the effect of Ubiquinol at 90 days compared to baseline on CogTrack composite measures of cognition. Additional cognitive measures, as well as measures of cardiovascular function, oxidative stress, liver function and mood will also be monitored across 30-, 60- and 90- day time points. Data analyses will involve repeated measures analysis of variance (ANOVA). Discussion: This study will be the first of its kind to provide important clinical and mechanistic data regarding the efficacy of Ubiquinol as a treatment for age-related cognitive decline in the healthy elderly with important implications for productivity and quality of life within this age group. Clinical Trial Registration: The trial has been registered with the Australian and New Zealand Clinical Trials Registry (ANZCTRN12618001841268).

Evidence and mechanisms for statin-induced cognitive decline.

INTRODUCTION: Statin drugs have become the most highly prescribed drugs for cardiovascular disease. However, there is disagreement as to the existence of adverse effects of statin administration on cognitive function. Therefore, it is important to better understand the effects of statins on cognition and possible mechanisms of these effects. Areas covered: We analyzed relevant studies of the relationship between cognitive performance and statin and usage. We included articles published between 2018 and 1992. We identified three randomized trials, one observational study and 66 case reports that provided credible evidence of statin-induced cognitive impairment. We also identified seven randomized trials and two observational studies reporting no significant evidence of statin-induced cognitive impairment. Expert opinion: We found methodological differences that may have contributed to the divergence of these results. Evaluation of all these studies indicated that statin-associated cognitive decline is a real entity. Likely mechanisms to explain the adverse effects include 1. Reduction of synthesis of coenzyme Q10 with consequent increasing oxidative stress and reduction of cerebral energy production; 2. Depletion of central nervous system myelin by inhibition of cholesterol synthesis. We conclude that statin-induced cognitive decline does exist, needs to be better recognized and requires more studies of prevention and treatment.

Prevalence of Zinc Deficiency in Cardiac Surgery Patients.

BACKGROUND: The aim of this study was to define the status of preoperative zinc levels in patients with heart disease presenting for cardiac surgery and to identify any predictors for and any clinical consequences of low zinc levels. METHODS: Adult patients presenting for elective surgery, either coronary artery bypass graft surgery and/or valve replacement, provided a fasting blood sample on the day of admission for surgery. Plasma and erythrocyte zinc levels were analysed and the levels correlated with the patient's characteristics and clinical outcomes. RESULTS: Of 56 patients 53% (n=30) had abnormally low plasma zinc levels (<12µmol/L) and 5.5% (n=3) had abnormally low erythrocyte zinc levels (<160µmol/L), indicative of deficiency. There were significant associations between lower plasma zinc levels and the presence of hypertension (p=0.02), hypercholesteraemia (p=0.02) and higher body mass index (BMI) (p=0.034) but no effect on major postoperative clinical outcomes. CONCLUSIONS: This small study shows that zinc deficiency is common in cardiac surgery patients, especially in the presence of hypertension, hypercholesterolaemia or obesity. The effects of zinc deficiency in cardiac surgery need to be further investigated.

A novel combination technique of cold crystalloid perfusion but not cold storage facilitates transplantation of canine hearts donated after circulatory death.

BACKGROUND: Donation after circulatory death (DCD) represents a potential new source of hearts to increase the donor pool. We showed previously that DCD hearts in Greyhound dogs could be resuscitated and preserved by continuous cold crystalloid perfusion but not by cold static storage and could demonstrate excellent contractile and metabolic function on an in vitro system. In the current study, we demonstrate that resuscitated DCD hearts are transplantable. METHODS: Donor Greyhound dogs (n = 12) were divided into perfusion (n = 8) and cold static storage (n = 4) groups. General anesthesia was induced and ventilation ceased for 30 minutes to achieve circulatory death. Donor cardiectomy was performed, and for 4 hours the heart was preserved by controlled reperfusion, followed by continuous cold perfusion with an oxygenated crystalloid perfusate or by static cold storage, after which orthotopic heart transplantation was performed. Recovery was assessed over 4 hours by hemodynamic monitoring. RESULTS: During cold perfusion, hearts showed continuous oxygen consumption and low lactate levels, indicating aerobic metabolism. The 8 dogs in the perfusion group were weaned off bypass, and 4 hours after bypass produced cardiac output of 4.73 ± 0.51 liters/min, left ventricular power of 7.63 ± 1.32 J/s, right ventricular power of 1.40 ± 0.43 J/s, and left ventricular fractional area shortening of 39.1% ± 5.2%, all comparable to pre-transplant values. In the cold storage group, 3 of 4 animals could not be weaned from cardiopulmonary bypass, and the fourth exhibited low-level function. CONCLUSIONS: Cold crystalloid perfusion, but not cold static storage, can resuscitate and preserve the DCD donor heart in a canine model of heart transplantation, thus rendering it transplantable. Controlled reperfusion and cold crystalloid perfusion have potential for clinical application in DCD transplantation.

Cold Crystalloid Perfusion Provides Cardiac Preservation Superior to Cold Storage for Donation After Circulatory Death.

BACKGROUND: We previously showed that donation after circulatory death (DCD) canine hearts can be resuscitated if perfused with warm blood. However, clinical application of this technique is complex and difficult. We have developed a simplified system of cold crystalloid perfusion and compared it with standard cold storage for DCD heart preservation. METHODS: Anesthetized greyhounds underwent 30 minutes DCD by withdrawal of ventilation followed by assignment to either 4 hours of perfusion (n = 6) or cold storage (n = 7). Nonpreserved hearts (n = 5) served as a normal reference group. Perfusion hearts were reperfused with a protective solution then perfused for 4 hours with a novel oxygenated, nutrient-containing solution at 20 mL/min at 4°C to 10°C. Cold storage hearts were flushed with St Thomas' cardioplegic solution and stored in ice. After preservation, the recovery of the hearts was assessed on a blood-perfused working heart rig. RESULTS: During preservation, perfusion hearts consumed oxygen (0.09 ± 0.01 mL/100 g per minute) and showed decreasing lactate production in the perfusate (initial: 0.031 ± 0.004 vs final: 0.007 ± 0.002 mmol/min; P = 0.001). After preservation, compared to cold storage hearts, perfusion hearts had higher cardiac output (P = 0.004), LV dP/dt max (P = 0.003) and myocardial oxygen efficiency (P = 0.01), with lower blood perfusate lactate (P = 0.007). Hemodynamic values of perfused hearts reached 60% or more those in the normal reference group. CONCLUSIONS: Continuous cold crystalloid perfusion in a canine model of DCD: (1) facilitates aerobic metabolism and resuscitates the DCD heart, (2) provides functional and metabolic recovery superior to cold storage, (3) shows promise for improved clinical preservation of DCD and marginal donor hearts.

Twelve-hour reanimation of a human heart following donation after circulatory death.

Despite increasing use of donation after cardiac death (DCD) and encouraging results for non-cardiac transplants, DCD cardiac transplantation has not been widely adopted because, (1) the DCD heart sustains warm ischaemic injury during the death process and (2) conventional static cold storage significantly adds to the ischaemic injury. We have developed a simple system for perfusion of the DCD heart with cold crystalloid solution using gravity-feed that can reduce ischaemic injury and potentially render the heart suitable for transplantation. This report describes the first application of this technique to a human DCD heart with good functional metabolic recovery over 12h on an ex vivo rig.

The effects of metallic implants on electroporation therapies: feasibility of irreversible electroporation for brachytherapy salvage.

PURPOSE: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. MATERIALS AND METHODS: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. RESULTS: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. CONCLUSION: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

Oxidative stress in surgery in an ageing population: pathophysiology and therapy.

Reactive oxygen species (ROS) play an important role in the regulation of normal cellular function. When ROS are produced in excess they can have detrimental effects, a state known as oxidative stress. Thus ROS play both physiological and pathophysiological roles in the body. In clinical practice oxidative stress and its counterpart, antioxidant capacity can be measured and can guide remedial therapy. Oxidative stress can have a negative impact in all forms of major surgery including cardiac surgery, general surgery, trauma surgery, orthopedic surgery and plastic surgery; this is particularly marked in an ageing population. Many different therapies to reduce oxidative stress in surgery have been tried with variable results. We conclude that in surgical patients the assessment of oxidative stress, improvement of the understanding of its role, both positive and negative, and devising appropriate therapies represent fruitful fields for future research.

Age-related decline in stress responses of human myocardium may not be explained by changes in mtDNA.

Elderly patients undergoing cardiac surgery are more likely to suffer postoperative heart failure than younger patients. This phenomenon is mirrored by an age-related loss of mitochondrial function and by an in vitro loss of myocardial contractile force following a stress. To examine the possibility that loss of mtDNA integrity may be responsible, we quantified representative age-associated mtDNA mutations (mtDNA(4977) and mtDNA(A3243G)) and mtDNA copy number using quantitative polymerase chain reaction in atrial samples obtained during cardiac surgery. The myocardium underwent organ bath contractility testing before and after either an ischaemic or hypoxic stress. We found that with age, recovery of developed force after either stressor significantly declined (p<0.0001). The abundance of mtDNA(4977) correlated weakly with loss of contractility (R(2)=0.09, p=0.047). However, the abundance level was low (average 0.0075% of total mtDNA) and the correlation disappeared when age was included in a multivariate analysis. Neither the abundance of mtDNA(A3243G) nor mtDNA copy number correlated with reduced recovery of developed force after stress. We conclude that, although mtDNA mutations (as exemplified by mtDNA(4977)) accumulate in the ageing heart, they are unlikely to make a major contribution to loss of contractile function.

The effects of ageing on the response to cardiac surgery: protective strategies for the ageing myocardium.

UNLABELLED: With ageing of the general population, increasing numbers of elderly patients are presenting for interventional cardiac treatment such as cardiac surgery, angioplasty and thrombolysis. However, the results of these interventions in the elderly are inferior to those in the young. A likely contributing factor is an age-related reduction in cellular energy production in the myocardium during interventions that induce aerobic or ischaemic stress. Coenzyme Q10 (CoQ10) has the potential to improve the efficiency of energy production in mitochondria by bypassing defective components in the respiratory chain as well as reducing the effects of oxidative stress. We hypothesised that CoQ10 pretreatment prior to stress could improve the post-stress recovery of the myocardium. We investigated this hypothesis in three studies. In Study 1, isolated hearts taken from senescent or mature rats, pre-treated with CoQ10 were subjected to rapid electrical pacing and the recovery of work after pacing as a percentage of pre-pacing level was measured. In Study 2, human atrial tissue obtained at the time of open heart surgery was subjected to simulated ischaemia in the organ bath after incubation with CoQ10 or vehicle and recovery measured. Study 3 was a clinical trial of oral CoQ10 therapy for 2 weeks pre-operatively in patients undergoing elective cardiac surgery. Study 1. CoQ10 treatment in senescent rat hearts improved recovery of work after rapid pacing (48.1+/-4.1 vs 16.8+/-4.3%; P < 0.0001) and MVO2 (82.1+/-2.8 vs 61.3+/-4.0%; P < 0.01) in treated versus untreated hearts respectively. Study 2. Post-ischaemic human trabeculae from the > or =70 years old group displayed less contractile recovery compared to the <70 years old group, but this difference was abolished by CoQ10 pre-incubation. Study 3: respiration by mitochondria isolated from trabeculae was more efficient after CoQ10 pretreatment than placebo. Compared to placebo, CoQ10 patients had a lower release of Troponin I, improved cardiac pump function and a shorter length of stay in hospital. IN CONCLUSION: 1) Senescent hearts have reduced baseline function and reduced tolerance to aerobic stress compared to young hearts. 2) Pre-treatment with oral CoQ10 improves baseline function of the senescent myocardium and its tolerance to aerobic stress. 3) CoQ10 pre-treatment in vitro overcomes the reduced capacity of aged human heart muscle to recover contractile function after ischaemia compared to younger muscle. 4) Oral CoQ10 therapy before cardiac surgery improves efficiency of mitochondrial energy production, improves post-operative heart function, reduces intra-operative myocardial damage and shortens hospital stay.

Coenzyme Q10 protects the aging heart against stress: studies in rats, human tissues, and patients.

With aging of the population, increasing numbers of elderly patients are presenting for cardiac surgery. However, the results in the elderly are inferior to those in the young. A likely contributing factor is an age-related reduction in cellular energy production in the myocardium during surgery, which is known to induce aerobic and ischemic stress. The lipophilic antioxidant and mitochondrial respiratory chain redox coupler, coenzyme Q10 (CoQ10), has the potential to improve energy production in mitochondria by bypassing defective components in the respiratory chain as well as by reducing the effects of oxidative stress. We hypothesized that CoQ10 pretreatment prior to stress could improve the recovery of the myocardium after stress.