Physiologic changes after brain death

Assessing the Brain Death/Death by Neurologic Criteria Determination Process in Korea: Insights from 10-Year Noncompleted Donation Data

BACKGROUND

This study aimed to analyze the current status of brain death/death by neurologic criteria (BD/DNC) determination in Korea over a decade, identifying key areas for improvement in the process.

METHODS

We conducted a retrospective analysis of data from the Korea Organ Donation Agency spanning 2011 to 2021, focusing on donors whose donations were not completed. The study reviewed demographics, medical settings, diagnoses, and outcomes, with particular emphasis on cases classified as nonbrain death and those resulting in death by cardiac arrest during the BD/DNC assessment.

RESULTS

Of the 5047 patients evaluated for potential brain death from 2011 to 2021, 361 were identified as noncompleted donors. The primary reasons for noncompletion included nonbrain death (n = 68, 18.8%), cardiac arrests during the BD/DNC assessment process (n = 80, 22.2%), organ ineligibility (n = 151, 41.8%), and logistical and legal challenges (n = 62, 17.2%). Notably, 25 (36.8%) of them failed to meet the minimum clinical criteria, and 7 of them were potential cases of disagreement between the two clinical examinations. Additionally, most cardiac arrests (n = 44, 55.0%) occurred between the first and second examinations, indicating management challenges in critically ill patients during the assessment period.

CONCLUSIONS

Our study highlights significant challenges in the BD/DNC determination process, including the need for improved consistency in neurologic examinations and the management of critically ill patients. The study underscores the importance of refining protocols and training to enhance the accuracy and reliability of brain death assessments, while also ensuring streamlined and effective organ donation practices.

The conceptual injustice of the brain death standard

Family disputes over the diagnosis of brain death have caused much controversy in the bioethics literature over the conceptual validity of the brain death standard. Given the tenuous status of brain death as death, it is pragmatically fruitful to reframe intractable debates about the metaphysical nature of brain death as metalinguistic disputes about its conceptual deployment. This new framework leaves the metaphysical debate open and brings into focus the social functions that are served by deploying the concept of brain death. In doing so, it highlights the epistemic injustice of medicolegal authorities that force people to uniformly accept brain death as a diagnosis of death based on normative considerations of institutional interests, such as saving hospital resources and organ supplies, rather than empirical evidence of brain death as death, which is insufficient at best and nonexistent at worst. In light of this injustice, I propose the rejection of the uniform standard of brain death in favor of a choice-based system that respects families' individualized views of death.

Intravenous Levothyroxine for Unstable Brain-Dead Heart Donors

BACKGROUND

Hemodynamic instability and myocardial dysfunction are major factors preventing the transplantation of hearts from organ donors after brain death. Intravenous levothyroxine is widely used in donor care, on the basis of observational data suggesting that more organs may be transplanted from donors who receive hormonal supplementation.

METHODS

In this trial involving 15 organ-procurement organizations in the United States, we randomly assigned hemodynamically unstable potential heart donors within 24 hours after declaration of death according to neurologic criteria to open-label infusion of intravenous levothyroxine (30 μg per hour for a minimum of 12 hours) or saline placebo. The primary outcome was transplantation of the donor heart; graft survival at 30 days after transplantation was a prespecified recipient safety outcome. Secondary outcomes included weaning from vasopressor therapy, donor ejection fraction, and number of organs transplanted per donor.

RESULTS

Of the 852 brain-dead donors who underwent randomization, 838 were included in the primary analysis: 419 in the levothyroxine group and 419 in the saline group. Hearts were transplanted from 230 donors (54.9%) in the levothyroxine group and 223 (53.2%) in the saline group (adjusted risk ratio, 1.01; 95% confidence interval [CI], 0.97 to 1.07; P = 0.57). Graft survival at 30 days occurred in 224 hearts (97.4%) transplanted from donors assigned to receive levothyroxine and 213 hearts (95.5%) transplanted from donors assigned to receive saline (difference, 1.9 percentage points; 95% CI, -2.3 to 6.0; P<0.001 for noninferiority at a margin of 6 percentage points). There were no substantial between-group differences in weaning from vasopressor therapy, ejection fraction on echocardiography, or organs transplanted per donor, but more cases of severe hypertension and tachycardia occurred in the levothyroxine group than in the saline group.

CONCLUSIONS

In hemodynamically unstable brain-dead potential heart donors, intravenous levothyroxine infusion did not result in significantly more hearts being transplanted than saline infusion. (Funded by Mid-America Transplant and others; ClinicalTrials.gov number, NCT04415658.).

Indexed donor cardiac output for improved size matching in heart transplantation: A United Network for Organ Sharing database analysis

Objective

Implantation of an appropriately sized donor heart is critical for optimal outcomes after heart transplantation. Although predicted heart mass has recently gained consideration, there remains a need for improved granularity in size matching, particularly among small donor hearts. We sought to determine if indexed donor cardiac output is a sensitive metric to assess the adequacy of a donor heart for a given recipient.

Methods

A retrospective analysis was performed (2003-2021) in isolated orthotopic heart transplant recipients from the United Network for Organ Sharing database. Donor cardiac output was divided by recipient body surface area to compute cardiac index (donor cardiac index). Predicted heart mass ratio was computed as donor/recipient predicted heart mass. The primary outcome was mortality 1 year after transplant.

Results

Among transplant recipients, median donor cardiac output was 7.3 (5.8-9.0) liters per minute and donor cardiac index was 3.7 (3.0-4.6) liters per minute/m2. Predicted heart mass ratio was 1.01 (0.91-1.13). After multivariable adjustment, higher donor cardiac index was associated with lower 1-year mortality risk (odds ratio, 0.92, P = .042). Recipients with predicted heart mass ratio less than 0.80 (n = 255) had a lower median donor cardiac index than those with a predicted heart mass ratio of 0.80 or greater (3.2 vs 3.7, P < .001). As predicted, heart mass ratio became smaller and the association between donor cardiac index and 1-year mortality became progressively stronger.

Conclusions

Higher donor cardiac index was associated with a lower probability of 1-year mortality among patients undergoing heart transplantation and served to further quantify mortality risk among those with a small predicted heart mass ratio. Donor cardiac index appears to be an effective tool for size matching and may serve as an adjunctive strategy among small donor hearts with a low predicted heart mass ratio.

Excitation and contraction of cardiac muscle and coronary arteries of brain-dead pigs

Excitability and contraction of cardiac muscle from brain-dead donors critically influence the success of heart transplantation. Membrane physiology, Ca²⁺-handling, and force production of cardiac muscle and the contractile properties of coronary arteries were studied in hearts of brain-dead pigs. Cardiac muscle and vascular function after 12 h brain death (decapitation between C2 and C3) were compared with properties of fresh tissue. In both isolated cardiomyocytes (whole-cell patch clamp) and trabecular muscle (conventional microelectrodes), action potential duration was shorter in brain dead, compared to controls. Cellular shortening and Ca²⁺ transients were attenuated in the brain dead, and linked to lower mRNA expression of L-type calcium channels and a slightly lower I_Ca,_L, current, as well as to a lower expression of phospholamban. The current-voltage relationship and the current above the equilibrium potential of the inward K⁺ (I_K1) channel were altered in the brain-dead group, associated with lower mRNA expression of the Kir2.2 channel. Delayed K⁺ currents were detected (I_Kr, I_Ks) and were not different between groups. The transient outward K⁺ current (I_to) was not observed in the pig heart. Coronary arteries exhibited increased contractility and sensitivity to the thromboxane analogue (U46619), and unaltered endothelial relaxation. In conclusion, brain death involves changes in cardiac cellular excitation which might lower contractility after transplantation. Changes in the inward rectifier K⁺ channel can be associated with an increased risk for arrhythmia. Increased reactivity of coronary arteries may lead to increased risk of vascular spasm, although endothelial relaxant function was well preserved.

Association of Donor Brain Death Due to Stroke With Prognosis After Heart Transplantation

BACKGROUND

The proximate cause of donor brain death is not considered a conventional risk factor in modern heart transplantation.

OBJECTIVES

This study aimed to investigate the effect of the cause of donor brain death on recipients.

METHODS

Using the United Network for Organ Sharing registry, long-term mortality and allograft failure were compared in recipients who underwent heart transplantation in the United States from 2005 through 2018 between allograft recipients from donors with stroke as the cause of brain death (n = 3,761) vs nonstroke causes (n = 14,677). Inverse probability weighting was used for risk adjustment. Interactions were investigated between the cause of brain death and other conventional donor risk factors for recipient mortality.

RESULTS

There was an interaction between the cause of brain death and donor age (P_interaction = 0.008). When allografts were procured from donors aged 40 years or younger, stroke as the cause of brain death was associated with an increased risk of mortality (23% vs 19% at 5 years; HR: 1.17; 95% CI: 1.02-1.35) and allograft failure (HR: 1.30; 95% CI: 1.04-1.63). When donors were older than 40 years, the cause of brain death was not associated with outcomes.

CONCLUSIONS

As the cause of donor brain death, stroke had a substantially different effect on recipient and allograft survival depending on donor age. In the case of younger donor ages, stroke was associated with higher recipient mortality and allograft failure than other causes of brain death. The strength of this association decreased with increasing donor age such that the increased hazard was no longer present in donors older than approximately 40 years.

A multicenter randomized placebo-controlled trial of intravenous thyroxine for heart-eligible brain-dead organ donors

Background

Brain death frequently induces hemodynamic instability and cardiac stunning. Impairments in cardiac performance are major contributors to hearts from otherwise eligible organ donors not being transplanted. Deficiencies in pituitary hormones (including thyroid-stimulating hormone) may contribute to hemodynamic instability, and replacement of thyroid hormone has been proposed as a means of improving stability and increasing hearts available for transplantation. Intravenous thyroxine is commonly used in donor management. However, small controlled trials have not been able to demonstrate efficacy.

Methods

This multicenter study will involve organ procurement organizations (OPOs) across the country. A total of 800 heart-eligible brain-dead organ donors who require vasopressor support will be randomly assigned to intravenous thyroxine for at least 12 h or saline placebo. The primary study hypotheses are that thyroxine treatment will result in a higher proportion of hearts transplanted and that these hearts will have non-inferior function to hearts not treated with thyroxine. Additional outcome measures are the time to achieve hemodynamic stability (weaning off vasopressors) and improvement in cardiac ejection fraction on echocardiography.

Discussion

This will be the largest randomized controlled study to evaluate the efficacy of thyroid hormone treatment in organ donor management. By collaborating across multiple OPOs, it will be able to enroll an adequate number of donors and be powered to definitively answer the critical question of whether intravenous thyroxine treatment increases hearts transplanted and/or provides hemodynamic benefits for donor management.

Trial registration

ClinicalTrials.govNCT04415658. Registered on June 4, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05797-2.

Mesenchymal stem cell-derived conditioned medium protects vascular grafts of brain-dead rats against in vitro ischemia/reperfusion injury

BACKGROUND

Brain death (BD) has been suggested to induce coronary endothelial dysfunction. Ischemia/reperfusion (IR) injury during heart transplantation may lead to further damage of the endothelium. Previous studies have shown protective effects of conditioned medium (CM) from bone marrow-derived mesenchymal stem cells (MSCs) against IR injury. We hypothesized that physiological saline-supplemented CM protects BD rats' vascular grafts from IR injury.

METHODS

The CM from rat MSCs, used for conservation purposes, indicates the presence of 23 factors involved in apoptosis, inflammation, and oxidative stress. BD was induced by an intracranial-balloon. Controls were subjected to a sham operation. After 5.5 h, arterial pressures were measured in vivo. Aortic rings from BD rats were harvested and immediately mounted in organ bath chambers (BD group, n = 7) or preserved for 24 h in 4 °C saline-supplemented either with a vehicle (BD-IR group, n = 8) or CM (BD-IR+CM group, n = 8), prior to mounting. Vascular function was measured in vitro. Furthermore, immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR) have been performed.

RESULTS

BD in donors was associated with significantly impaired hemodynamic parameters and higher immunoreactivity of aortic myeloperoxidase (MPO), nitrotyrosine, caspase-3, caspase-8, caspase-9, and caspase-12 compared to sham-operated rats. In organ bath experiments, impaired endothelium-dependent vasorelaxation to acetylcholine in the BD-IR group compared to BD rats was significantly improved by CM (maximum relaxation to acetylcholine: BD 81 ± 2% vs. BD-IR 50 ± 3% vs. BD-IR + CM 72 ± 2%, p < 0.05). Additionally, the preservation of BD-IR aortic rings with CM significantly lowered MPO, caspase-3, caspase-8, and caspase-9 immunoreactivity compared with the BD-IR group. Furthermore, increased mRNA expression of vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1 in the aortas from the BD-IR rats compared to BD group were significantly decreased by CM.

CONCLUSIONS

The preservation of BD rats' vascular grafts with CM alleviates endothelial dysfunction following IR injury, in part, by reducing levels of inflammatory response and caspase-mediated apoptosis.

Brain-dead donor heart conservation with a preservation solution supplemented by a conditioned medium from mesenchymal stem cells improves graft contractility after transplantation

Hearts are usually procured from brain-dead (BD) donors. However, brain death may induce hemodynamic instability, which may contribute to posttransplant graft dysfunction. We hypothesized that BD-donor heart preservation with a conditioned medium (CM) from mesenchymal stem cells (MSCs) would improve graft function after transplantation. Additionally, we explored the PI3K pathway's potential role. Rat MSCs-derived CM was used for conservation purposes. Donor rats were either exposed to sham operation or brain death by inflation of a subdural balloon-catheter for 5.5 hours. Then, the hearts were explanted, stored in cardioplegic solution-supplemented with either a medium vehicle (BD and sham), CM (BD + CM), or LY294002, an inhibitor of PI3K (BD + CM + LY), and finally transplanted. Systolic performance and relaxation parameters were significantly reduced in BD-donors compared to sham. After transplantation, systolic and diastolic functions were significantly decreased, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and endonuclease G positive cells were increased in the BD-group compared to sham. Preservation of BD-donor hearts with CM resulted in a recovery of systolic graft function (dP/dt_max : BD + CM: 3148 ± 178 vs BD: 2192 ± 94 mm Hg/s at 110 µL, P < .05) and reduced apoptosis. LY294002 partially lowered graft protection afforded by CM in the BD group. Our data suggest that PI3K/Akt pathway is not the primary mechanism of action of CM in improving posttransplant cardiac contractility and preventing caspase-independent apoptosis.

Vascular Signaling in Allogenic Solid Organ Transplantation - The Role of Endothelial Cells

Graft rejection remains the major obstacle after vascularized solid organ transplantation. Endothelial cells, which form the interface between the transplanted graft and the host’s immunity, are the first target for host immune cells. During acute cellular rejection endothelial cells are directly attacked by HLA I and II-recognizing NK cells, macrophages, and T cells, and activation of the complement system leads to endothelial cell lysis. The established forms of immunosuppressive therapy provide effective treatment options, but the treatment of chronic rejection of solid organs remains challenging. Chronic rejection is mainly based on production of donor-specific antibodies that induce endothelial cell activation—a condition which phenotypically resembles chronic inflammation. Activated endothelial cells produce chemokines, and expression of adhesion molecules increases. Due to this pro-inflammatory microenvironment, leukocytes are recruited and transmigrate from the bloodstream across the endothelial monolayer into the vessel wall. This mononuclear infiltrate is a hallmark of transplant vasculopathy. Furthermore, expression profiles of different cytokines serve as clinical markers for the patient’s outcome. Besides their effects on immune cells, activated endothelial cells support the migration and proliferation of vascular smooth muscle cells. In turn, muscle cell recruitment leads to neointima formation followed by reduction in organ perfusion and eventually results in tissue injury. Activation of endothelial cells involves antibody ligation to the surface of endothelial cells. Subsequently, intracellular signaling pathways are initiated. These signaling cascades may serve as targets to prevent or treat adverse effects in antibody-activated endothelial cells. Preventive or therapeutic strategies for chronic rejection can be investigated in sophisticated mouse models of transplant vasculopathy, mimicking interactions between immune cells and endothelium.

N-octanoyl dopamine is superior to dopamine in protecting graft contractile function when administered to the heart transplant recipients from brain-dead donors

The major source of heart transplantation comes from brain-dead (BD) donors. However, brain death and myocardial ischemia/reperfusion injury during transplantation may lead to cardiac dysfunction and hemodynamic instability. A previous work demonstrated that pre-treatment of BD donors with dopamine improved the graft survival of heart allograft in recipient after transplantation. However, low-dose dopamine treatment might result in tachycardia and hypertension. Our previous experimental study showed that pre-treatment of BD donor rats with the dopamine derivate N-octanoyl dopamine (NOD), devoid of any hemodynamic effects, improved graft function after transplantation. Herein, we hypothesized that NOD confers superior myocardial protection than dopamine, in terms of graft function. Male Lewis donor rats were either subjected to sham-operation or brain death via a subdurally placed balloon followed by 5.5 h monitoring. Then, the hearts were explanted and heterotopically transplanted into Lewis recipient rats. Shortly before the onset of reperfusion, continuous intravenous infusion of either NOD (14.7 μg/kg/min, BD + NOD group, n = 9), dopamine (10 μg/kg/min, BD + Dopamine group, n = 8) or physiological saline vehicle (sham, n = 9 and BD group, n = 9) were administered to the recipient rats. In vivo left-ventricular (LV) graft function was evaluated after 1.5 h reperfusion. Additionally, immunohistochemical detection of 4-hydroxy-2-nonenal (HNE, an indicator of oxidative stress) and nitrotyrosine (a nitro-oxidative stress marker), was performed. After heart transplantation, systolic and diastolic functions were significantly decreased in the BD group compared to sham. Treatment with NOD but not dopamine, resulted in better LV graft systolic functional recovery (LV systolic pressure BD + NOD 90 ± 8 vs BD + Dopamine 66 ± 5 vs BD 65 ± 4 mmHg; maximum rate of rise of LV pressure dP/dt_max BD + NOD 2686 ± 225 vs BD + Dopamine 2243 ± 70 vs BD 1999 ± 147 mmHg/s, at an intraventricular volume of 140 μl, p < 0.05) and myocardial work compared to BD group. The re-beating time (time to restoration of heartbeat) was significantly shorter in BD + NOD group than that of BD hearts (32 ± 4 s vs. 48 ± 6 s, p < 0.05), Dopamine treatment had no impact on all of these parameters. Furthermore, NOD as well as dopamine decreased HNE and nitrotyrosine immunoreactivity to the same level. NOD is superior to dopamine in terms of protecting LV graft contractile function when administered to the heart transplant recipients from BD donors.

Improved long-term outcomes after heart transplantation utilizing donors with a traumatic mode of brain death

Background

The donor’s mode of brain death (BD), being associated with impairment of myocardial function and hemodynamic performance, impacts the prognosis of the heart transplantation (HTx) recipient.

Methods

All patients who underwent HTx between 1996 and 2017 were categorized according to donor’s BD mechanism: traumatic BD (TBD) versus non-traumatic BD (NTBD).

Results

The TBD group included 105 recipients, and the NTBD group, 85 recipients. Kaplan-Meier survival analysis showed that overall survival was significantly higher for recipients of TBD hearts (10-year survival 58.1 vs. 37.6%, p = 0.044). Consistently, multivariate analysis showed that TBD was independently associated with a significant 43% reduction in mortality [95% confidence interval (CI) 0.42–0.75, p = 0.033]. Rejection rate was lower in the TBD group (total rejection score 0.44 ± 0.32 vs. 0.51 ± 0.38, p = 0.04; any rejection score 0.38 ± 0.26 vs. 0.45 ± 0.31, p = 0.030), and freedom from cardiac allograft vasculopathy (CAV) was significantly higher in recipients of traumatic vs. non-traumatic donors (10 years: 82.9 vs. 62.4%, log-rank p-value = 0.024). Multivariate analysis showed a significant 42% reduction in CAV [hazard ratio (HR) = 0.58, 95% CI 0.51–0.85, p = 0.022).

Conclusion

Mode of brain death significantly impacts HTx outcomes, with TBD being associated with reduced mortality, rejections and CAV.

Biomarkers and Donor Selection in Heart Transplantation

BACKGROUND

Previously, we showed that B-type natriuretic peptide (BNP) measured in the donor was related to cardiac performance after cardiac transplantation. The present study assesses the value of 3 biomarkers in the selection of donor hearts in a larger cohort.

METHODS

Blood samples were prospectively obtained in 105 brain-dead patients scheduled for heart donation. BNP, soluble suppressor of tumorigenicity 2 (ST2), and troponin of heart donors were correlated with hemodynamic parameters early after transplantation as well as with the mortality of the recipients.

RESULTS

A significant inverse relationship was found between donor BNP measured at the time of donation and recipient cardiac index and cardiac output at day 13 post-transplantation (r = -0.31, P = .005, and r = -0.34, P = .0016, respectively). Logistic regression analysis-including BNP, ST2, and troponin-showed that donor BNP was a predictor of a poor cardiac index (< 2.2 L/min/m²) in the recipient (P = .04). A donor BNP > 132 pg/mL has a sensitivity of 56% (95% confidence interval 21-86) and a specificity of 86% (95% confidence interval 77-93) to predict poor cardiac performance in the recipient. When the donor BNP is ≤ 132 pg/mL, the risk of a poor cardiac function in the recipient is very low (negative predictive value 94%). Mortality at 30 days was also correlated to donor BNP (r = 0.29, P = .0029). Long-term survival of the recipient was not correlated to the biomarkers measured in the donor.

CONCLUSION

Donor BNP, but not donor ST2 or high-sensitivity troponin, provides information on the donor heart and early post-transplant performance, including 1-month mortality.

Does duration of donor brain injury impact heart transplantation outcomes?

AIM

We aimed to study the implications of pre-transplantation time intervals on HT outcomes.

METHODS

Brain injury time (BIT) was defined as the period from the donor brain injury to brain death declaration. Brain death interval (BDI) was defined as the period from brain death to application of an aortic cross-clamp during donor heart procurement. Allograft ischemia was defined as the time from donor aortic cross-clamp to aortic unclamping. End points included mortality and rejections.

RESULTS

Between 1997 and 2017, we assessed 173 patients. Kaplan-Meier analyses showed that prolonged donor BIT, BDI, allograft ischemia, and total injury time had no significant effect on mortality and rejections. Patients were subdivided into short BIT (<97 hours, n = 87) and long BIT (≥97 hours, n = 86) groups. No differences in rejection scores nor in time to first rejection were noted. Kaplan-Meier analysis showed a similar long-term survival in the two groups. Sub-analysis of both groups according to their median BDI (12 hours) revealed no differences in mortality or time to rejection.

CONCLUSIONS

Pre-transplantation time intervals do not affect mortality or rejection. Our findings have important clinical implications regarding HT allocation and organ availability.

Brain death interval and relationship to outcomes of pediatric cardiac transplantation

BACKGROUND

We sought to analyze brain death interval and outcomes of pediatric cardiac transplantation using national registry data.

METHODS

We retrospectively evaluated a pediatric cohort from the UNOS registry from 2005 to 2014. We restricted the donor cohort to those with a primary central nervous system event as the cause of hospitalization. Brain death interval (BDI) was defined as the time between hospital admission and organ procurement. Primary outcomes were recipient and graft survival time. Logistical regression modeling was used for multivariable analysis.

RESULTS

The donor cohort included 2565 cases. Multivariable analysis demonstrated no relationship between BDI and recipient or graft survival time. For patient survival time, the lowest HR was 0.94 (0.63-1.39), P = 0.531; for graft survival time, the lowest HR was 0.89 (0.53-1.49), P = 0.563. We obtained similar results using a non-restricted donor cohort.

CONCLUSIONS

There was no clear relationship between BDI and recipient or graft survival after pediatric cardiac transplantation.

Donor Preconditioning After the Onset of Brain Death With Dopamine Derivate n-Octanoyl Dopamine Improves Early Posttransplant Graft Function in the Rat

Heart transplantation is the therapy of choice for end-stage heart failure. However, hemodynamic instability, which has been demonstrated in brain-dead donors (BDD), could also affect the posttransplant graft function. We tested the hypothesis that treatment of the BDD with the dopamine derivate n-octanoyl-dopamine (NOD) improves donor cardiac and graft function after transplantation. Donor rats were given a continuous intravenous infusion of either NOD (0.882 mg/kg/h, BDD+NOD, n = 6) or a physiological saline vehicle (BDD, n = 9) for 5 h after the induction of brain death by inflation of a subdural balloon catheter. Controls were sham-operated (n = 9). In BDD, decreased left-ventricular contractility (ejection fraction; maximum rate of rise of left-ventricular pressure; preload recruitable stroke work), relaxation (maximum rate of fall of left-ventricular pressure; Tau), and increased end-diastolic stiffness were significantly improved after the NOD treatment. Following the transplantation, the NOD-treatment of BDD improved impaired systolic function and ventricular relaxation. Additionally, after transplantation increased interleukin-6, tumor necrosis factor TNF-α, NF-kappaB-p65, and nuclear factor (NF)-kappaB-p105 gene expression, and increased caspase-3, TNF-α and NF-kappaB protein expression could be significantly downregulated by the NOD treatment compared to BDD. BDD postconditioning with NOD through downregulation of the pro-apoptotic factor caspase-3, pro-inflammatory cytokines, and NF-kappaB may protect the heart against the myocardial injuries associated with brain death and ischemia/reperfusion.

Cardiac Dysrhythmias during Donor Care

Organ procurement coordinators must treat various cardiac dysrhythmias (arrhythmias), including rhythm disturbances that may cause or follow a cardiac arrest, in about 15% to 50% of donors. Treatment decisions should be based on the particular dysrhythmia and its effect on donor blood pressure. Medications selected should be effective but short acting. In this article, data available in publications located through a PubMed search are reviewed and specific dysrhythmias that are likely to occur during donor care are described. Treatment recommendations are based on guidelines from the American Heart Association.

Treatment Goals during Care of Adult Donors That Can Influence Outcomes of Heart Transplantation

Myocardial dysfunction during care of adult donors can result from injury occurring before hospital admission or during the progression of brain death. Few evidence-based data correlate specific hemodynamic goals during donor care with outcomes of heart transplantation, although many recommendations exist. Spontaneous reversal of early heart damage or correction of poor cardiac performance can yield outcomes equivalent to outcomes in recipients who had ideal donors. Hemodynamic goals developed in the operating room can be applied in intensive care to improve outcomes of transplantation. These goals include maintenance of mean arterial pressure greater than 60 mm Hg, central venous pressure less than 12 mm Hg, cardiac output greater than 3.8 L/min, cardiac index greater than 2.1, and systemic vascular resistance between 800 and 1200 dyne · sec · cm−5. The ejection fraction and other echocardiographic data also provide helpful guidance when determining whether a heart is suitable for transplantation and during therapy. Titration of cardiovascular variables often requires invasive monitoring to ensure that cardiac preload, afterload, and contractility are optimal.

Successful transplantation in canines after long-term coronary sinus machine perfusion preservation of donor hearts

BACKGROUND

Machine perfusion is a promising strategy for donor heart preservation, but delivery of perfusate through the aorta may be limited by aortic valve incompetence. We hypothesized that retrograde machine perfusion preservation through the coronary sinus avoided this issue and allowed for recovery of donor hearts after long-term storage.

METHODS

Canine hearts were procured after arrest with 1 liter University of Wisconsin Machine Perfusion Solution (UWMPS) and preserved for 14 hours by static hypothermic storage (Static group, n = 5) or retrograde machine perfusion through the coronary sinus (RP group, n = 5). Myocardial oxygen consumption (MVo2) and lactate were monitored in perfused hearts. Hearts were implanted and reperfused for 6 hours. The pre-load recruitable stroke work was determined as a measure of myocardial function. Cardiac enzyme release was quantified. Cell death was evaluated by TUNEL (terminal deoxynucleotidyltransferase-mediated deoxy uridine triphosphate nick-end label).

RESULTS

MVo2 decreased initially then stabilized. Lactate accumulation was low in RP hearts. All RP hearts separated from cardiopulmonary bypass. All Static hearts required a return to bypass (p < .05). Pre-load recruitable stroke work in RP hearts was increased (55 ± 7 mm Hg) compared with Static (20 ± 11 mm Hg, p < .05) and did not differ from baseline values. Creatine kinase release was greater in Static group hearts (102 ± 16 IU/liter/g) than in RP hearts (51 ± 8 IU/liter/g, p < .05). The fraction of TUNEL-positive cells was higher in the Static group, but this difference was not significant.

CONCLUSIONS

Retrograde machine perfusion can preserve donor hearts for long intervals. Cardiac function after implantation suggested excellent myocardial protection. Retrograde machine perfusion appears promising for extending the donor ischemic interval and improving results of heart transplantation.

Dimethyloxalylglycine treatment of brain-dead donor rats improves both donor and graft left ventricular function after heart transplantation

OBJECTIVE

Hypoxia inducible factor (HIF)-1 pathway signalling has a protective effect against ischemia/reperfusion injury. The prolyl-hydroxylase inhibitor dimethyloxalylglycine (DMOG) activates the HIF-1 pathway by stabilizing HIF-1α. In a rat model of brain death (BD)-associated donor heart dysfunction we tested the hypothesis that pre-treatment of brain-dead donors with DMOG would result in a better graft heart condition.

METHODS

BD was induced in anesthetized Lewis rats by inflating a subdurally placed balloon catheter. Controls underwent sham operations. Then, rats were injected with an intravenous dose of DMOG (30 mg/kg) or an equal volume of physiologic saline. After 5 hours of BD or sham operation, hearts were perfused with a cold (4°C) preservation solution (Custodiol; Dr. Franz Köhler Chemie GmbH; Germany), explanted, stored at 4°C in Custodiol, and heterotopically transplanted. Graft function was evaluated 1.5 hours after transplantation.

RESULTS

Compared with control, BD was associated with decreased left ventricular systolic and diastolic function. DMOG treatment after BD improved contractility (end-systolic pressure volume relationship E'max: 3.7 ± 0.6 vs 3.1 ± 0.5 mm Hg/µ1; p < 0.05) and left ventricular stiffness (end-diastolic pressure volume relationship: 0.13 ± 0.03 vs 0.31 ± 0.06 mm Hg/µ1; p < 0.05) 5 hours later compared with the brain-dead group. After heart transplantation, DMOG treatment of brain-dead donors significantly improved the altered systolic function and decreased inflammatory infiltration, cardiomyocyte necrosis, and DNA strand breakage. In addition, compared with the brain-dead group, DMOG treatment moderated the pro-apoptotic changes in the gene and protein expression.

CONCLUSIONS

In a rat model of potential brain-dead heart donors, pre-treatment with DMOG resulted in improved early recovery of graft function after transplantation. These results support the hypothesis that activation of the HIF-1 pathway has a protective role against BD-associated cardiac dysfunction.

Anesthetic considerations in organ procurement surgery: a narrative review

PURPOSE

While a few publications specify the anesthetic implications of either brain or cardiac death, they lack detail on how to provide anesthesia during organ donation surgery. We provide a thorough description of important anesthetic considerations during organ donation surgery in patients with either brain or cardiac death.

SOURCE

A thorough literature review was undertaken to locate all relevant articles that describe systemic effects of brain and cardiac death and their anesthetic implications. We searched PubMed, Pubget, and EMBASE™ for relevant articles using the following search terms: anesthesia, management, donation cardiac death, donation brain death. In addition, we reviewed the relevant protocols at our own institution.

PRINCIPAL FINDINGS

Highly specific intraoperative management by an anesthesiologist is required during organ procurement after brain death. To manage the heart-beating brain-dead donor, the anesthesiologist must incorporate knowledge of the effects of brain death on each organ system as well as the effects of the preoperative measures that the donor required in the intensive care unit. It is also important to know which organs are going to be procured in order to establish specific goals and implement strategies (e.g., lung-protective ventilation or intraoperative glycemic control) to optimize donor outcome. During organ procurement after cardiac death, an anesthesiologist's direct involvement is particularly important for lung donors.

CONCLUSION

Anesthesiologist-guided physiological optimization of the brain-dead donor may be a factor in determining the outcome of the organ recipient. Additionally, anesthesiologists have an important role in helping to ensure that the highest quality and most appropriate care are rendered to non-heart-beating donors. This is achieved through establishing protocols in their hospitals for donation after cardiac death that maximize the number of available organs with the best chance for long-term graft viability.

Short- and long-term effects of brain death on post-transplant graft function in a rodent model

OBJECTIVES

Heart transplantation has become the most effective treatment for end-stage heart failure. Donors after brain death (BD) are currently the only reliable source for cardiac transplants. However, haemodynamic instability and cardiac dysfunction have been demonstrated in brain-dead donors and this could therefore also affect post-transplant graft function. We studied the effects of BD on cardiac function and its short-term (1 h) or long-term (5 h) impacts on graft function.

METHODS

In Lewis rats, BD was induced by inflation of a subdurally placed balloon catheter (n = 7). Sham-operated rats served as controls (n = 9). We continuously assessed cardiac function by left ventricular (LV) pressure-volume analysis. Then, 1 or 5 h after BD or sham operation, hearts were perfused with a cold preservation solution (Custodiol), then explanted, stored at 4°C in Custodiol and heterotopically transplanted. We evaluated graft function 1.5 h after transplantation.

RESULTS

BD was associated with decreased left ventricular contractility (ejection fraction: 37 ± 6 vs 57 ± 5%; maximum rate of rise of LV pressure dP/dtmax: 4770 ± 197 vs 7604 ± 348 mmHg/s; dP/dtmax-end-diastolic volume: 60 ± 7 vs 74 ± 2 mmHg/s; slope Emax of the end-systolic pressure-volume relationship: 2.4 ± 0.1 vs 4.4 ± 0.3 mmHg/µl; preload recruitable stroke work: 47 ± 9 vs 78 ± 3 mmHg; P <0.05) and relaxation (maximum rate of fall of left ventricular pressure dP/dtmin: -6638 ± 722 vs -11 285 ± 539 mmHg/s; time constant of left ventricular pressure decay Tau: 12.6 ± 0.7 vs 10.5 ± 0.4 ms; end-diastolic pressure-volume relationship: 0.22 ± 0.05 vs 0.09 ± 0.03 mmHg/µl, P <0.05) 45 min after its initiation and for the rest of 5 h compared with controls. Moreover, after transplantation, graft systolic and diastolic functions were impaired in the 5-h brain-dead group, while they were identical in the 1-h brain-dead group compared with the corresponding controls.

CONCLUSIONS

We established a well-characterized in vivo rat model to examine the influence of BD on cardiac function using a miniaturized technology for pressure-volume analysis. These results demonstrate that impaired donor cardiac function after short-term BD is reversible after transplantation and long-term BD renders hearts more susceptible to ischaemia/reperfusion injury.

Hypothermic continuous machine perfusion improves metabolic preservation and functional recovery in heart grafts

The number of heart transplants is decreasing due to organ shortage, yet the donor pool could be enlarged by improving graft preservation. Hypothermic machine perfusion (MP) has been shown to improve kidney, liver, or lung graft preservation. Sixteen pig hearts were recovered following cardioplegia and randomized to two different groups of 4-hour preservation using either static cold storage (CS) or MP (Modified LifePort© System, Organ Recovery Systems, Itasca, Il). The grafts then underwent reperfusion on a Langendorff for 60 min. Energetic metabolism was quantified at baseline, postpreservation, and postreperfusion by measuring lactate and high-energy phosphates. The contractility index (CI) was assessed both in vivo prior to cardioplegia and during reperfusion. Following reperfusion, the hearts preserved using CS exhibited higher lactate levels (56.63 ± 23.57 vs. 11.25 ± 3.92 μmol/g; P < 0.001), increased adenosine monophosphate/adenosine triphosphate (AMP/ATP) ratio (0.4 ± 0.23 vs. 0.04 ± 0.04; P < 0.001), and lower phosphocreatine/creatine (PCr/Cr) ratio (33.5 ± 12.6 vs. 55.3 ± 5.8; P <0.001). Coronary flow was similar in both groups during reperfusion (107 ± 9 vs. 125 + /-9 ml/100 g/min heart; P = ns). CI decreased in the CS group, yet being well-preserved in the MP group. Compared with CS, MP resulted in improved preservation of the energy state and more successful functional recovery of heart graft.

The effect of total spinal anesthesia on cardiac function in a large animal model of brain death

Brain death (BD) causes cardiac dysfunction in organ donors, attributable to the catecholamine storm that occurs with raised intracerebral pressure (ICP). However the direct contribution of the spinal sympathetics has not been well described. We examined the effect of total spinal anesthesia (TSA) on cardiac function in a large animal model of BD. Eighteen pigs were allocated to 3 experimental groups: Group 1, the saline-treated control group; Group 2, TSA administered prior to BD; and Group 3, TSA administered 30 min after BD. Inflation of an intracerebral balloon-tipped catheter was used to induce BD. Ventricular function was assessed using a pressure–volume loop catheter and magnetic resonance imaging. Serum catecholamine levels were assessed with high performance liquid chromatography. Inflation of the intracerebral balloon-tipped catheter was associated with a dramatic rise in heart rate and blood pressure, along with increased concentrations of serum epinephrine and norepinephrine. This phenomenon was not observed in Group 2. In Group 1, there was a significant decline in contractility, whereas groups 2 and 3 saw no change. Group 2 had greater contractile reserve than groups 1 and 3. Our data demonstrate the central role of spinal sympathetics in the hemodynamic response to raised ICP. Further work is required to determine the utility of TSA in reversing cardiac dysfunction in BD donors.

Mechanical ventilation during anaesthesia: challenges and opportunities for investigating the respiration-related cardiovascular oscillations

The vast majority of the available literature regarding cardiovascular oscillations refers to spontaneously breathing subjects. Only a few studies investigated cardiovascular oscillations, and especially respiration-related ones (RCVO), during intermittent positive pressure mechanical ventilation (IPPV) under anaesthesia. Only a handful considered assisted IPPV, in which spontaneous breathing activity is supported, rather than replaced as in controlled IPPV. In this paper, we review the current understanding of RCVO physiology during IPPV, from literature retrieved through PubMed website. In particular, we describe how during controlled IPPV under anaesthesia respiratory sinus arrhythmia appears to be generated by non-neural mechano-electric feedback in the heart (indirectly influenced by tonic sympathetic regulation of vascular tone and heart contractility) and not by phasic vagal modulation of central origin and/or baroreflex mechanisms. Furthermore, assisted IPPV differs from controlled IPPV in terms of RCVO, reintroducing significant central respiratory vagal modulation of respiratory sinus arrhythmia. This evidence indicates against applying to IPPV interpretative paradigms of RCVO derived from spontaneously breathing subjects, and against considering together IPPV and spontaneously breathing subjects for RCVO-based risk assessment. Finally, we highlight the opportunities that IPPV offers for future investigations of RCVO genesis and interactions, and we indicate several possibilities for clinical applications of RCVO during IPPV.

Brain death provokes very acute alteration in myocardial morphology detected by echocardiography: preventive effect of beta-blockers

Our objective was to evaluate immediate acute changes in myocardial function during the autonomic storm of brain death (BD). Wistar rats were divided into four groups (n = 8/group): controls without any treatment, β-blocker (Esmolol®, 10 mg/kg), calcium channel blocker (Diltiazem®, 10 mg/kg), or alpha-blocker (Prazosin®, 0.3 mg/kg). Treatments were administered intravenously 5 min before BD induction. Echocardiography (ATL-5000, 8 MHz) was performed to measure left ventricular (LV) dimensions and fractional shortening at baseline, during BD induction and 5 min and 15 min after BD. In controls, BD was immediately associated with an increase in wall thickness and a decrease in LV cavity dimension. This myocardial wall hypertrophy was completely prevented by β-blockers, but not with calcium- and alpha-blockers. Extensive myocardial interstitial edema was found in all groups, except in the β-blocker group. Myocardial wall hypertrophy was also prevented during a longer follow-up of 180 min after BD in β-blocker group as opposed to controls. In conclusion, BD is associated with an immediate and severe myocardial damage related to an important interstitial edema which is prevented by β-blockers.

p38 Mitogen-activated protein kinase inhibition reduces inflammatory cytokines in a brain-dead transplant donor animal model

The aim of this study was to determine the degree of p38 mitogen-activated protein kinase (p38 MAPK) activation in rat heart and lungs after experimentally induced brain death and to test whether SD-282, a synthetic and selective small molecule inhibitor of p38 MAPK, abrogates p38 MAPK activation invoked by this brain death model.

METHODS

Adult male Sprague Dawley rats were treated with vehicle (control, n=7) or SD-282 (40mg/kg, n=6), for 15min prior to the induction of brain death and maintained with ventilatory support for 3h. IL-6 and TNFalpha were measured in plasma, heart and lungs using ELISA, and p38 MAPK via Western blot assay.

RESULTS

p38 MAPK inhibition was demonstrated by lower p38 MAPK activity in lungs from SD-282-treated donors compared to control (Median [inter-quartile range]: 13.6[4.0-19.0]% vs 20.2[14.7-31.5]% activity, p=0.06). Although levels varied, significant inhibition of p38 MAPK by SD-282 was not observed in the heart. SD-282 significantly lowered IL-6 and TNFalpha values compared to control in plasma (64[51-81]pg/ml vs 352[200-755]pg/ml, p=0.003 and 4.3[1.5-9.0]pg/ml vs 21.1[10.5-31.5]pg/ml, p=0.015, respectively) and lungs (0.14[0.12-0.62] vs 5.8[3.6-6.0]pg/mg protein, p=0.03 and 0.41[0.33-0.45] vs 2.1[1.4-2.7]pg/mg protein, p=0.0027, respectively), however SD-282 did not significantly affect cardiac cytokine levels.

CONCLUSIONS

p38 MAPK inhibition with SD-282 decreases the pro-inflammatory response as represented by lower IL-6 and TNFalpha in plasma and lungs following brain death. However, although in heart this response was variable, no significant effect could be demonstrated under the present conditions.

Progression of organ failure in patients approaching brain stem death

We performed a retrospective cohort study to document the progression of organ dysfunction in 182 critically ill adult patients who subsequently met criteria for brain stem death (BSD). Patients were admitted to intensive care units (ICUs) of Mayo Medical Center, Rochester, MN, between January 1996 and December 2006. Daily sequential organ failure assessment (SOFA) scores were used to assess the degree of organ dysfunction. Serial SOFA scores were analyzed using analysis of variance (ANOVA). Mean (standard deviation, SD) SOFA score on the first ICU day was 8.9 (3.2). SOFA scores did not significantly change over the course of ICU stay. 67.6% of patients donated one or more organs after BSD was declared. The median time from ICU admission to declaration of BSD was 18.8 h (interquartile range 10.3-45.0), and in those who donated organs, the time from declaration of BSD to organ retrieval was 11.8 h (9.5-17.6). The fact that mean SOFA scores did not change significantly over time, even after BSD occurred, has implications for the timing of retrieval of organs for transplantation.

Activation and modulation of cardiac poly-adenosine diphosphate ribose polymerase activity in a rat model of brain death

DNA damage during transplantation can activate poly-adenosine diphosphate ribose polymerase (PARP) resulting in the generation of polymers of adenosine diphosphate-ribose (PAR). Excessive linkage of PAR to nuclear proteins can induce cell death, thereby limiting the function of transplanted organs. This study uses a rat model of brain death to determine the profile of PARP activation and whether mechanisms that lead to cell death can be ameliorated by appropriate donor resuscitation. The expression of PAR-linked nuclear proteins within cardiac myocytes was greatly increased after the induction of donor brain death. Importantly, infusion of noradrenaline or vasopressin to normalize the chronic hypotension produced by brain death reduced the expression of PAR to a level below baseline. These data suggest that chronic hypotension after donor brain death has the potential to limit cardiac function through the activation of PARP; however, this early cause of graft damage can be mitigated by appropriate donor resuscitation.

L-arginine improves endothelial and myocardial function after brain death

BACKGROUND

Recently, we showed that brain death (BD) leads to a severe impairment of endothelial function.

METHODS

To test the hypothesis, that nitric oxide supply improves endothelial function, we infused L-arginine (40 mg/kg) in 6 dogs after BD induction (subdural balloon). Six vehicle-treated BD animals served as controls. Coronary blood flow (CBF), preload recruitable stroke work (PRSW), and plasma L-arginine and nitrite/nitrate levels were measured before and 6 hr after BD induction. In addition, endothelium-dependent vasodilatation after intracoronary application of acetylcholine (ACH) and endothelium-independent vasodilation after sodium nitroprusside (SNP) were assessed.

RESULTS

Six hours after BD, CBF decreased significantly in the control group (38.2+/-3.5 vs. 26.8+/-3.1 ml/min, P<0.05), whereas the decrease was less pronounced in the L-arginine group (41.8+/-6.9 vs. 36.0+/-1.2 ml/min, P<0.05 vs. control). Before BD, ACH led to a similar vasodilative response in both groups (81+/-6 vs. 75+/-7%). After BD, a paradox vasoconstriction occurred after ACH in the control group, while the vasodilative response did not change in the L-Arginine group (36+/-6 vs. 69+/-7%, P<0.05). The response to SNP did not differ between the groups and over the time. After BD PRSW decreased in both groups, however, it was still significantly higher in the L-arginine group (56+/-7 vs. 71+/-7 kerg, P<0.05). L-arginine (711+/-144 vs. 234+/-54 microM P<0.05) and nitrite/nitrate (39+/-3 vs. 27+/-3 microM P<0.05) levels were significantly higher in the L-arginine group.

CONCLUSION

L-arginine treatment prevents endothelial dysfunction and improves myocardial performance after BD via enhancement of endogenous nitric oxide synthesis.

Aturdimiento miocárdico neurogénico

The existence of stunned myocardium and reversible myocardial dysfunction is widely described and accepted in patients suffering ischemic heart disease. However, it cannot be exclusive to coronary disease. Classically, the appearance of electrocardiographic changes in the critical neurological disease has been described. However, at present, it seems to be observed that some of these patients with critical neurological disease could have variable grades of myocardial dysfunction, which is generally reversible in the surviving patients. This myocardial dysfunction, which could affect critically ill neurological patients, has traits similar to stunned myocardium generated in coronary patients since: a) it is generally associated to electrocardiographic changes, b) it can be accompanied by segmental contractility disorders and even c) it may be accompanied by a certain increase of cardiac biomarkers. Although its etiopathogeny is unknown, it could be related with the severity of the primary neurological disease. Its prophylaxis and prognosis are also unknown. It could be related with neurogenic edema, with hemodynamic instability, and could also play a very important role in brain death and in organ donation.

Glucocorticoid administration reduces cardiac dysfunction after brain death in pigs

BACKGROUND

Traumatic brain injury and subsequent brain death (BD) account for nearly half of all organ donors, yet only 33% of available hearts are transplanted. Alterations in multiple physiologic pathways after BD can lead to cardiac dysfunction and exclusion from transplantation. Triple hormone resuscitation with methylprednisolone, thyroid hormone and vasopressin has had inconsistent results in the effort to reduce cardiac dysfunction associated with BD, but individual analysis of these agents is limited. The hypothesis was that glucocorticoid administration alone could reduce BD-associated cardiac dysfunction.

METHODS

Crossbred pigs (25 to 35 kg) had BD induced by sub-dural balloon inflation. Hemodynamics were measured for 360 minutes after BD. Negative cerebral perfusion pressures and decreased laser Doppler cerebral blood flow confirmed BD. Animals (n = 5/treatment group) received: saline (Group 1); 30 mg/kg methylprednisolone 2 hours before BD (Group 2); or 30 mg/kg methylprednisolone 1 hour after BD (Group 3). Repeated measures analysis of variance and unpaired t-tests were used for appropriate comparisons.

RESULTS

Left ventricular (LV) pre-load recruitable stroke work (PRSW) decreased in untreated Group 1 over time (p < 0.001), whereas PRSW in animals treated with glucocorticoids, Groups 2 and 3, was not different from baseline at 360 minutes after BD. Diastolic function measured as LV -dP/dt (minimum derivative of the change in pressure over time) and tau (time constant of isovolumic relaxation) was also preserved 360 minutes after brain death by glucocorticoids in Groups 2 and 3 (p > 0.05). Oxygen delivery 360 minutes after BD was higher in Group 2 compared with Group 1 (p = 0.02) and Group 3 (p = 0.006).

CONCLUSIONS

Glucocorticoid therapy before or after BD preserved LV systolic and diastolic function. Glucocorticoids administered after brain death might increase the number of hearts available for transplant by reducing brain death-associated cardiac dysfunction.