Activation of apoptotic and inflammatory pathways in dysfunctional donor hearts

Analyse des critères qui participent à la décision de prélèvement cardiaque chez les patients en état de mort encéphalique

OBJECTIVES

The number of cardiac transplantation procedures does not increase because of the lack of donor hearts despite an increase in the number of brain-dead organ donors. The criteria used to select a donor heart are not formally standardized. The aim of the present study was to analyze the criteria that contribute to the selection of a donor heart.

TYPE OF STUDY

Descriptive, retrospective study.

PATIENTS AND METHOD

Clinical parameters, the initial causes that lead to brain death, maximum doses of catecholamines, several biochemical markers of myocardial ischaemia/necrosis as well as several echocardiography criteria were extracted from a prospectively collected database. Univariate and multivariate (logistic regression) analyses were performed with the "harvested heart" as dependent variable and the above-cited independent variables.

RESULTS

One hundred and eighty consecutive brain-dead patients admitted from 1st October 1998 to 31st December 2000 out of which 112 gave at least one organ were analyzed. Among these 112 patients, 59 (39 males and 20 females) were pre-selected as potential heart donors. Only 44 hearts were harvested. Logistic regression analysis showed that harvesting of the heart was more probable if the donor were a male, had no left ventricle systolic wall motion abnormalities, had low doses of norepinephrine and low serum troponin Ic concentrations.

CONCLUSION

After an initial phase of selection, the final decision to harvest a heart is based on several criteria. These results should be an incentive to conceive a score that could allow a more formal decision process for heart harvesting.

Functional evidence of reversible ischemic injury immediately after the sympathetic storm associated with experimental brain death

BACKGROUND

Acute brain death from increased intracranial pressure results in a transient increase in myocardial adenosine and lactate, which indicates that oxygen demand exceeds oxygen delivery during the sympathetic "storm". The aim of this study was to determine the functional significance of this period of ischemia.

METHODS

Brain death was inflicted on 40 Westran pigs (36.5-68.0 kg) by inflating a 21-ml subdural balloon over 3 minutes. In 38 animals, micromanometry and sonomicrometry were used to obtain left ventricular pressure-volume loops to determine the preload recruitable stroke work (PRSW) relationship. Data files were recorded before and at 15-minute intervals after beginning balloon inflation. Plasma troponin I was measured before and 60 minutes after beginning balloon inflation in the 38 instrumented and 2 non-instrumented animals.

RESULTS

All animals experienced the classical sympathetic storm. The slope of the PRSW relationship decreased, and the volume-axis intercept shifted to the right 15 minutes after beginning balloon inflation (p < 0.0001). Progressive incremental recovery (leftward shift) occurred between subsequent time points (p < or = 0.0018). In the instrumented animals, the mean plasma troponin I level increased from 1.4 +/- 1.6 microg/liter to 2.8 +/- 2.3 microg/liter (p < 0.001). However, troponin I was not detected before or after induction of brain death in the plasma of either non-instrumented animal (p = 0.001).

CONCLUSIONS

The sympathetic storm produced transient contractile dysfunction, consistent with ischemic injury. However, troponin I release reflected surgical instrumentation and not brain death.

Prognostic significance of free radicals: mediated injury occurring in the kidney donor

BACKGROUND

Brain death is associated with hemodynamic disturbances in systemic circulation and metabolic storm, and, thus, free radical-mediated injury to donor tissues was hypothesized. An assessment of oxidative stress in the donor and its effect on posttransplant kidney graft function comprised the scope of the study.

METHODS

A prospective study was performed in 27 donors and 50 kidney transplant recipients. Sera from 27 brain-dead organ donors and preservation media were tested for malondialdehyde (MDA) and for total antioxidant status (TAS). Kidneys were preserved in University of Wisconsin-gluconate solution with machine perfusion. Mean ischemia time was 36.7+/-8 hours. Organs were transplanted to recipients on the Polish National Waiting List and posttransplant kidney function was monitored periodically. Posttransplant delayed graft function (DF) was diagnosed when a patient required at least one dialysis within first week after transplantation. Acute rejection was diagnosed clinically and confirmed with fine-needle biopsy if necessary.

RESULTS

Thirty-two recipients had immediate graft function (IF), and 18 suffered from DF. MDA level in preservation solution at the end of machine perfusion was significantly higher in the DF group (52.6+/-31 vs. 25.3+/-19 micromol/L) whereas donor TAS activity was lower (1.14+/-0.2 vs. 0.97+/-0.3 mmol/mL). Patients who suffered from acute rejection received kidneys from donors with significantly higher serum MDA (66+/-73 micromol/ml vs. 23+/-49 for patients without rejection). Serum creatinine 12 to 48 months after transplantation correlated to donor- and preservation-solution MDA (P<0.006).

CONCLUSIONS

Free-radical mediated injury occurring in the donor and during preservation is strictly correlated with immediate and long-term kidney function. It may also cause grafts to be prone to acute rejection.

Extended somatic support for pregnant women after brain death

OBJECTIVE

To review case reports of pregnant women who have been supported after brain death until successful delivery of their infants. From these reports and other literature about brain death, normal physiologic changes of pregnancy, and specific needs for fetal development, recommendations were made to assist in supporting pregnant women after brain death until delivery of a mature fetus who is likely to survive.

DATA SOURCES

Personal files and experiences, MEDLINE review of case reports and publications about physiologic changes present during normal pregnancy and after brain death, and the critical needs for fetal development were included.

DATA EXTRACTION

Eleven reports of ten patients comprise the accumulated clinical experience. Hypotension, requiring fluid administration and inotropic/vasopressor therapy, occurred in all the mothers, and in six cases, was the reason for urgent delivery. The longest period of support was 107 days, from 15 to 32 wks of gestation. Two mothers also became organ donors. Recurrent infections, thermolability, and other complications common to prolonged ICU care were encountered. All infants survived. One had congenital abnormalities caused by phenytoin use by the mother. When followed, all others developed within normal growth and mental variables. These cases plus literature citations noted above were used to develop recommendations for maternal/fetal care.

CONCLUSION

Preservation of uterine/placental blood flow is the most important priority during somatic support. Imprecise autoregulation of the uterine vasculature during maternal hypoxemia or hypotension makes this goal a significant challenge. Special considerations for nutrition; medication use; cardiovascular, respiratory, or endocrine therapy; fetal monitoring; hormone replacement; and ethical concerns are discussed.

Effects of gene induction and cytokine production in donor care

Gene induction, cytokine production, and programmed neuronal and myocardial cell death are concerns that have entered the areas of donor evaluation and care over the past several years. Following ischemic or traumatic brain injury and the evolution of brain death, a large number of proteins (cytokines) are produced as part of a regional inflammatory response. These cytokines and related compounds appear to contribute to programmed death (apoptosis) of individual cells and the severe cardiac and hemodynamic changes often encountered during donor care. In addition, these cytokines and related compounds may sensitize donor organs so that a faster and more severe form of rejection occurs in the recipient. Although no directed therapy for these cytokine effects is presently available, the organ procurement coordinator should be aware of these issues and concerns as new treatment options evolve in the near future.

Ubiquitous expression of phosphodiesterase 7A in human proinflammatory and immune cells

We have determined the expression of phosphodiesterase (PDE) 7A1 and PDE7A2 in human cells that have been implicated in the pathogenesis of chronic obstructive pulmonary disease and asthma. Messenger RNA transcripts were detected by RT-PCR in T lymphocytes, monocytes, neutrophils, airway and vascular smooth muscle cells, lung fibroblasts, epithelial cells, and cardiac myocytes. Human epithelial, T cell, eosinophil, and lung fibroblast cell lines were also positive for PDE7A1 and PDE7A2 mRNA transcripts. By Western immunoblot analyses the amount of PDE7A1 was greatest in T cell lines, peripheral blood T lymphocytes, epithelial cell lines, airway and vascular smooth muscle cells, lung fibroblasts, and eosinophils but was not detected in neutrophils. In contrast, PDE7A2 protein, which was identified in human cardiac myocytes, was not found in any of the other cell types investigated. Immunoconfocal analyses showed that PDE7A was expressed in neutrophils and alveolar macrophages. As the expression of PDE7A mirrors the distribution of PDE4 we speculate that this enzyme could be a target for novel anti-inflammatory drugs.