Successful transplantation of hearts harvested 30 minutes after death from exsanguination

Heart Donation From Donors After Controlled Circulatory Death

The gold-standard therapy for advanced-stage heart failure is cardiac transplantation. Since the first heart transplant in 1967, the majority of hearts transplanted came from brain death donors. Nevertheless, in recent years, the option of donation after circulatory death (DCD) is gaining importance to increase donor pool. Currently, heart-transplant programs using controlled donation after circulatory death (cDCD) have been implemented in the United Kingdom, Belgium, Australia, United States of America, and, recently, in Spain. In this article, we performed a concise review of the literature in heart cDCD; we summarize the pathophysiology involved in ischemia and reperfusion injury during this process, the different techniques of heart retrieval in cDCD donors, and the strategies that can be used to minimize the damage during retrieval and until transplantation. Heart transplant using DCD hearts is in continuous improvement and must be implemented in experienced cardiac transplant centers.

Transplantation of Hearts Donated after Circulatory Death

Cardiac transplantation has become limited by a critical shortage of suitable organs from brain-dead donors. Reports describing the successful clinical transplantation of hearts donated after circulatory death (DCD) have recently emerged. Hearts from DCD donors suffer significant ischemic injury prior to organ procurement; therefore, the traditional approach to the transplantation of hearts from brain-dead donors is not applicable to the DCD context. Advances in our understanding of ischemic post-conditioning have facilitated the development of DCD heart resuscitation strategies that can be used to minimize ischemia-reperfusion injury at the time of organ procurement. The availability of a clinically approved ex situ heart perfusion device now allows DCD heart preservation in a normothermic beating state and minimizes exposure to incremental cold ischemia. This technology also facilitates assessments of organ viability to be undertaken prior to transplantation, thereby minimizing the risk of primary graft dysfunction. The application of a tailored approach to DCD heart transplantation that focuses on organ resuscitation at the time of procurement, ex situ preservation, and pre-transplant assessments of organ viability has facilitated the successful clinical application of DCD heart transplantation. The transplantation of hearts from DCD donors is now a clinical reality. Investigating ways to optimize the resuscitation, preservation, evaluation, and long-term outcomes is vital to ensure a broader application of DCD heart transplantation in the future.

Heart transplantation from donation after circulatory determined death

Fifty years since the first successful human heart transplant from a non-heart beating donor, this concept of heart transplantation from donation after circulatory determined death (DCD) promises to be one of the most exciting developments in heart transplantation. Heart transplantation has established itself as the best therapeutic option for patients with end-stage heart failure, with the opportunity to provide these patients with a near-normal quality of life. However, this treatment is severely limited by the availability of suitable donor hearts. In recent times, heart transplantation has been limited to using donor hearts from donors following brain stem death. The use of donor hearts from DCD had been thought to be associated with high risk and poor outcomes until recent developments in organ perfusion and retrieval techniques have shown that this valuable resource may provide an answer to the global shortage of suitable donor hearts. With established DCD heart transplant programmes reporting encouraging results, this technique has been shown to be comparable to the current gold standard of donation after brain death (DBD) heart transplantation.

The Death Watch: Certifying Death Using Cardiac Criteria

In the past, inadequate diagnostic instruments sometimes led to incorrect diagnoses of death, so careful and prolonged observation—the “death watch”—was required. Diagnostic instruments are now accurate and determining the presence or absence of circulation and cerebral function is easy in virtually all cases. Still, ambiguity and controversy in diagnosing death persists because the current criteria, irreversible cessation of cardiac or whole brain function, are ambiguous. Recent reintroduction of Non—Heart-beating organ donation has highlighted the controversy. Data on the ability to achieve restoration of spontaneous circulation are quite consistent, but they support several different sets of reasonable death criteria. This article concludes with a rejection of a fixed notion of “irreversibility” because it does not conform to current practice, is potentially deleterious to social events at the time of death, and the reversibility of cardiopulmonary arrest is dependent on available means of resuscitation. Finally, the time required to ensure irreversible cessation of cardiac function despite potential intervention is too broad to be clinically applicable and is unreasonable. Diagnosis of death should be based on the context in which it occurs because the medical means available determine what is irreversible.

Functional assessment and transplantation of the donor heart after circulatory death

BACKGROUND

After a severe shortage of brain-dead donors, the demand for heart transplantation has never been greater. In an attempt to increase organ supply, abdominal and lung transplant programs have turned to the donation after circulatory-determined death (DCD) donor. However, because heart function cannot be assessed after circulatory death, DCD heart transplantation was deemed high risk and never adopted routinely. We report a novel method of functional assessment of the DCD heart resulting in a successful clinical program.

METHODS

Normothermic regional perfusion (NRP) was used to restore function to the arrested DCD heart within the donor after exclusion of the cerebral circulation. After weaning from support, DCD hearts underwent functional assessment with cardiac-output studies, echocardiography, and pressure-volume loops. In the feasibility phase, hearts were transported perfused before evaluation of function in modified working mode extracorporeally. After the establishment of a reliable assessment technique, hearts with demonstrable good function were then selected for clinical transplantation.

RESULTS

NRP was instituted in 13 adult DCD donors, median age of 33 years (interquartile range [IQR], 28-38 years), after a median ischemic time from withdrawal to perfusion of 24 minutes (IQR, 21-29; range, 17-146 minutes). Two of 4 hearts in the feasibility phase were unsuitable for transplantation after functional assessment. Nine DCD hearts were transplanted in the clinical phase, with 100% survival. The median intensive care duration was 5 days (IQR, 4-5 days), with 2 patients requiring mechanical support. There were no episodes of rejection (total, 1,436 patient-days; range, 48-297). During the same period, we performed 20 standard heart transplants using brain-dead donors.

CONCLUSIONS

NRP allows rapid reperfusion and functional assessment of the DCD donor heart, ensuring only viable hearts are selected for transplantation. This technique minimizes the risk of primary graft dysfunction and maximizes confidence in DCD heart transplantation, realizing a 45% increase in our heart transplant activity.

Early reperfusion hemodynamics predict recovery in rat hearts: a potential approach towards evaluating cardiac grafts from non-heart-beating donors

Aims

Cardiac grafts from non-heartbeating donors (NHBDs) could significantly increase organ availability and reduce waiting-list mortality. Reluctance to exploit hearts from NHBDs arises from obligatory delays in procurement leading to periods of warm ischemia and possible subsequent contractile dysfunction. Means for early prediction of graft suitability prior to transplantation are thus required for development of heart transplantation programs with NHBDs.

Methods and Results

Hearts (n = 31) isolated from male Wistar rats were perfused with modified Krebs-Henseleit buffer aerobically for 20 min, followed by global, no-flow ischemia (32°C) for 30, 50, 55 or 60 min. Reperfusion was unloaded for 20 min, and then loaded, in working-mode, for 40 min. Left ventricular (LV) pressure was monitored using a micro-tip pressure catheter introduced via the mitral valve. Several hemodynamic parameters measured during early, unloaded reperfusion correlated significantly with LV work after 60 min reperfusion (p<0.001). Coronary flow and the production of lactate and lactate dehydrogenase (LDH) also correlated significantly with outcomes after 60 min reperfusion (p<0.05). Based on early reperfusion hemodynamic measures, a composite, weighted predictive parameter, incorporating heart rate (HR), developed pressure (DP) and end-diastolic pressure, was generated and evaluated against the HR-DP product after 60 min of reperfusion. Effective discriminating ability for this novel parameter was observed for four HR*DP cut-off values, particularly for ≥20 *10³ mmHg*beats*min⁻¹ (p<0.01).

Conclusion

Upon reperfusion of a NHBD heart, early evaluation, at the time of organ procurement, of cardiac hemodynamic parameters, as well as easily accessible markers of metabolism and necrosis seem to accurately predict subsequent contractile recovery and could thus potentially be of use in guiding the decision of accepting the ischemic heart for transplantation.

Outcome in 757 severely injured patients with traumatic cardiorespiratory arrest

BACKGROUND

Resuscitation of traumatic cardiorespiratory arrest patients (TCRA) is generally associated with poor outcome, however some authors report survival rates of more than 10% in blunt trauma patients. The purpose of this investigation was to determine predictive factors for mortality in trauma patients having received external chest compressions (ECC).

PATIENTS AND METHODS

Twenty thousand eight hundred and fifteen patients from the Trauma Registry of the German Trauma Society were analysed (mean ISS=24.0). Inclusion criteria were ISS>/=16 and available information on ECC either on-scene and/or during trauma room treatment. Included into the Trauma Registry were only patients with ECC and transportation into a hospital. Patients declared dead on-scene without transportation to a hospital were not recorded in the data base. A Logistic regression was performed to find out predictive factors for mortality.

RESULTS

Ten thousand three hundred and fifty nine patients fulfilled the inclusion criteria. N=757 patients received ECC, 415 prehospital, 538 during trauma room (TR) treatment and 196 prehospital and in-hospital. Blunt trauma occurred in 93.2%, mean age was 40.3 and median ISS was 41.0. 23.2% of the patients were treated with a chest tube, 5.7% had a tension pneumothorax and 10.2% underwent emergency thoracotomy. The overall survival rate was 17.2%. 9.7% of the TCRA patients with ECC achieved good recovery or moderate disability (Glasgow outcome scale>/=4). Logistic regression showed thromboplastin time lower than 50% to be the strongest predictor for non-survival (OR 5.2, 95% CI 2.3-11.9), followed by massive blood transfusion of more than 10 units of packed red blood cells (OR 4.8, 95% CI 2.0-11.5), on-scene blood pressure of 0 (OR 4.3, 95% CI 1.6-11.3), age over 55 (OR 2.9, 95% CI 1.1-7.3), base excess lower than -8 (OR 2.7, 95% CI 1.2-5.9). The insertion of a chest tube on-scene could be detected as a factor significantly increasing the probability of survival (OR 0.3, 95% CI 0.13-0.8).

CONCLUSIONS

Prehospital chest tube insertion was found to be a strong predictor for survival. On-scene chest decompression of TCRA patients is recommended in case of the decision to start with ECC. Based on our data, resuscitation after severe trauma seems to be more justified than the current guidelines state.

Prediction of functional recovery of 60-minute warm ischemic hearts from asphyxiated canine non-heart-beating donors

BACKGROUND

Cardiac function of non-heart-beating donors (NHBDs) is uncertain due to severe myocardial damage. We developed an isolated myocardial perfusion system to resuscitate NHBD hearts and attempted to predict functional recovery of 60-minute warm ischemic hearts by analyzing systolic and diastolic functions.

METHODS

Hypoxic cardiac arrest was induced in 8 mongrel dogs without any pre-treatments. After 60-minute ischemia, intracoronary microthrombi were flushed out by retrograde blood cardiopledia with tissue-type plasminogen activator. Coronary arteries were initially perfused from the aortic root with tepid hyperkalemic blood (20 mmol/liter) at low pressure (20 mm Hg) for the first 60 minutes and then with normothermic blood for the next 60 minutes. After 120 minutes of reperfusion, pre-load was increased for ejection against an after-load of 80 mm Hg. Pressure-volume loops were recorded to obtain the end-systolic pressure-volume relationship (ESPVR) and end-diastolic pressure-volume relationship (EDPVR). Stroke volume at a given pre-load was calculated from averaged ESPVR, EDPVR and after-load identical to an averaged baseline value. The Frank-Starling relationship was obtained and cardiac status was classified according to Forrester's hemodynamic sub-set.

RESULTS

End-systolic elastance decreased significantly to about 60% of baseline and the time constant of isovolumic relaxation was prolonged significantly by about 20%. Cardiac index was decreased to about 50% and cardiac status was classified in the Forrester III or IV sub-set.

CONCLUSIONS

The extent of functional recovery of NHBD hearts is predictable by cardiac output. Although 120 minutes of recovery time may be short for 60-minute ischemic damage, this system may be feasible to predict post-transplant cardiac function before transplantation.

Potential Suitability for Transplantation of Hearts From Human Non–Heart-Beating Donors: Data Review From the Gift of Life Donor Program

BACKGROUND

Organ availability limits use of heart transplantation for treatment for end-stage heart disease. Hearts are currently obtained from donors declared brain dead (heart-beating donors [HBDs]). Although use of hearts from non-heart-beating donors (NHBDs) could reduce the shortage, they are considered unusable because of possible peri-mortem ischemic injury.

METHODS

To project how use of NHBD hearts could increase heart donation, we retrospectively reviewed donor databases from the Gift of Life Donor Program (GLDP), our local organ procurement organization, from 2001 through 2003. We screened the NHBD population using conservative donor criteria, assuming an acceptable hypoxic/ischemic time (time from withdrawal of care to cross-clamp) of 30 minutes.

RESULTS

During the study period, there were 894 HBDs, 334 heart transplants and 119 NHBDs. NHBDs were similar to HBDs with respect to gender and ethnicity, but NHBDs were proportionately younger. Of 119 NHBDs, 55 did not meet the age criteria (< or =45 years) and 20 were eliminated because of incomplete data. Eighty-two NHBDs were cross-clamped within 30 minutes of care withdrawal. Twenty NHBDs met all cardiac donor criteria, and 14 of these 20 had hypoxic/ischemic times < or =30 minutes. Pro rata estimation for the 20 NHBDs with incomplete data suggested 7 potential additional donors.

CONCLUSIONS

Based on our assumptions, 12% to 18% of NHBDs in the study period (14 to 21 of 119 total) were potential heart donors, representing a 4% to 6% increase over of the number of heart transplants performed during the same time interval.

Donor management and selection for heart transplantation

The success of cardiac transplantation has led to its widespread application for all etiologies of end-stage heart disease. As a result, this has resulted in a severe shortage of available donor organs. In light of an increasing organ demand with a stable supply, efficacious donor management and meticulous selection is crucial in maintaining excellent outcomes with cardiac transplantation. It is now increasingly common to push the envelope by expanding criteria for donor selection. This has translated into harvesting of older donor hearts, from more unstable donors as well as from more distant locations. Of utmost importance is that when the decision is made to proceed with cardiac transplantation, the risk/benefit ratio associated with cardiac transplantation in that particular patient must be weighed against the mortality and morbidity risk while remaining on the heart transplant waiting list.

EMERGENCY DONOR HEART PROTECTION: APPLICATION OF THE PORT ACCESS CATHETER TECHNIQUE USING A PIG HEART TRANSPLANTATION MODEL1

BACKGROUND

Organ shortage limits the number of transplantations, and donor deterioration may precede and often prevent conventional organ preservation. This study evaluates in situ perfusion as a bedside method for cardiac allograft procurement in a large animal model.

METHODS

Thirty Landrace pigs (42 +/- 7 kg) were studied. The hearts in the conventional group underwent cardioplegic arrest with University of Wisconsin solution and sodium-hydrogen exchange inhibitor cariporide as an additive; they were explanted and stored on ice before transplantation. In the in situ group, one catheter was placed in the ascending aorta and another in the right atrium. After disconnection from the ventilator, hypoxia caused circulatory arrest. The aorta was endoclamped, and in situ perfusion of the aortic root was maintained with University of Wisconsin solution and cariporide. After explantation, hearts were stored on ice for 120 min. All hearts were implanted according to the Shumway technique. Ventricular pressure and cardiac output were monitored online, and troponin-I was measured intermittently. Two hours after weaning from extracorporal circulation, the animals were killed and histology was performed.

RESULTS

Catheters were placed through introducers within 5 min. Functional recovery and histology were comparable between the two techniques. Troponin-I increased in both groups during reperfusion but at a faster rate in the in situ technique (P <0.01).

CONCLUSION

In situ perfusion may be suitable for cardiac transplants when donor deterioration requires urgent organ preservation. Catheters can be placed at bedside and modified to achieve multi-organ protection through additional perfusion of the abdominal aorta.

Non-heart-beating donors in thoracic transplantation

Access to lung transplantation is severely limited by a scarcity of suitable donors, resulting in increasing numbers of deaths on the heart and lung transplant waiting lists, and strict selection criteria for recipients. Unlike some other solid organs, the lung may be ideally suited to retrieval for transplant following substantial intervals after circulatory arrest. This may be because lung parenchymal cells do not rely on perfusion for cellular respiration. This review outlines the relevant published experimental data that addresses the concept that lungs might be suitable for transplant even if retrieved from non-heart-beating donors (NHBDs), and the small published clinical experience with NHBDs as lung donors. Aspects of reperfusion injury in this setting are reviewed. The prospect of heart transplant from NHBDs is addressed. The impact of the routine use of NHBDs on lung transplantation is discussed.

Nicorandil ameliorates posttransplant dysfunction in cardiac allografts harvested from non-heart-beating donors

OBJECTIVE

Warm ischemia is a major cause of cardiac allograft dysfunction in non-heart-beating donors (NHBDs). We evaluated the cardioprotective effects of nicorandil, an adenosine triphosphate-sensitive potassium channel opener, on the early posttransplant left ventricular (LV) function of hearts harvested from asphyxiated canine NHBDs.

METHODS

Hypoxic cardiac arrest was induced in 12 donor dogs. In 6, nicorandil was administered intravenously at 100 micrograms/kg + 25 micrograms/kg/min after respiratory arrest and hearts were preserved with nicorandil-supplemented cardioplegic solution (nicorandil group). The remaining 6 did not receive nicorandil at any time during the experiment (control group). Hearts were orthotopically transplanted after a mean myocardial ischemic time of 4 hours.

RESULTS

All 12 recipients were weaned from cardiopulmonary bypass without inotropic support. In the control group, posttransplant cardiac indices and left ventricular end-systolic pressure (LVESP) decreased significantly, while LV max-dP/dt and Tau increased over pretransplant values. No differences were seen in parameters between pretransplant and posttransplant values in the nicorandil group. Posttransplant cardiac indices, LVESP, and LV max + dP/dt were higher in the nicorandil group than in controls, while posttransplant LV max-dP/dt in the nicorandil group was lower.

CONCLUSIONS

Our results indicate that pretreatment with nicorandil during hypoxic perfusion before cardiac arrest and subsequent preservation with nicorandil-supplemented cardioplegia ameliorates early posttransplant LV dysfunction of hearts harvested from asphyxiated NHBDs.

The death watch: certifying death using cardiac criteria

In the past, inadequate diagnostic instruments sometimes led to incorrect diagnoses of death, so careful and prolonged observation--the "death watch"--was required. Diagnostic instruments are now accurate and determining the presence or absence of circulation and cerebral function is easy in virtually all cases. Still, ambiguity and controversy in diagnosing death persists because the current criteria, irreversible cessation of cardiac or whole brain function, are ambiguous. Recent reintroduction of non-heart-beating organ donation has highlighted the controversy. Data on the ability to achieve restoration of spontaneous circulation are quite consistent, but they support several different sets of reasonable death criteria. This article concludes with a rejection of a fixed notion of "irreversibility" because it does not conform to current practice, is potentially deleterious to social events at the time of death, and the reversibility of cardiopulmonary arrest is dependent on available means of resuscitation. Finally, the time required to ensure irreversible cessation of cardiac function despite potential intervention is too broad to be clinically applicable and is unreasonable. Diagnosis of death should be based on the context in which it occurs because the medical means available determine what is irreversible.

Posttransplant function of a nonbeating heart is predictable by an ex vivo perfusion method

BACKGROUND

We attempted to predict the posttransplant cardiac function of nonbeating donor hearts.

METHODS

A total of 13 dogs were studied. Hearts were left in situ for 45 minutes after cardiac arrest caused by exsanguination. Hearts were then excised and reperfused in an ex vivo perfusion apparatus after 60 minutes of warm ischemia to test whether they could eject against an 80 mm Hg afterload from a preload of 10 mm Hg. Thereafter, all hearts were transplanted orthotopically.

RESULTS

Four of 13 hearts were able to eject in the apparatus (group A). However, the other nine hearts could not eject under the defined conditions (group B). All four hearts in group A showed good posttransplant hemodynamics (systolic arterial pressure > 80 mm Hg with mean left atrial pressure < 10 mm Hg) without dopamine. However, none of nine hearts in group B could support the circulation without dopamine.

CONCLUSIONS

Nonbeating donor heart function evaluated in the perfusion apparatus predicts posttransplant heart function. This method may be applicable for selection of transplantable hearts from nonbeating heart donors.

A new hydroxyl radical scavenger "EPC" on cadaver heart transplantation in a canine model

This study was performed to determine if an "arrested" heart, resuscitated with cardiopulmonary bypass (CPB) after the cessation of beating, can be successfully transplanted, and whether a hydroxyl radical scavenger EPC can reduce ischemic and reperfusion injury during resuscitation of the arrested heart and following orthotopic heart transplantation. A total of 16 pairs of canines were divided into a control group of eight pairs and an EPC-treated group of eight pairs. Cardiac arrest of the donor heart was induced by the discontinuation of respiratory support after the induction of brain death. The cadaver heart was then resuscitated and core-cooled to myocardial temperature of 15 degrees C using CPB. The donor heart was harvested using cold cardioplegia and orthotopically transplanted. All of the transplanted hearts in the EPC group were weaned from CPB without any inotropic support after 60 min of bypass support, whereas all the animals in the control group required 5 micrograms/kg/min dopamine (P = 0.001). Moreover, cardiac function (Emax) 1 h after orthotopic heart transplantation was better preserved in the EPC group than in the control group, at 110 +/- 36% vs. 70 +/- 21% of the post brain death values (P = 0.02) These findings demonstrate that EPC reduces posttransplant reperfusion injury, and thus it may prove to be a valuable adjunct in this challenging model.

Non-heart-beating organ donation: a defense of the required determination of death

The family of a patient who is unconscious and respirator-dependent has made a decision to discontinue medical treatment. The patient had signed a donor card. The family wants to respect this decision, and agrees to non-heart-beating organ donation. Consequently, as the patient is weaned from the ventilator, he is prepped for organ explantation. Two minutes after the patient goes into cardiac arrest, he is declared dead and the transplant team arrives to begin organ procurement. At the time retrieval begins, it is not certain that the patient's brain is dead or that cardiac function cannot be restored. Procurement follows uneventfully, and two transplantable kidneys are retrieved.

Many people now consider such cases of non-heart-beating organ donation to be ethically permissible. However, widespread disagreement persists as to how such practices are to be justified and whether such practices are compatible with the Uniform Declaration of Death Act (UDDA). In this paper, I argue that non-heart-beating organ donation can be ethically justified, that in the justified cases the patients are in fact dead, and that the early declarations of death required for such donation do comply with the UDDA.

Warm ischemic tolerance in collapsed pulmonary grafts is limited to 1 hour

OBJECTIVE

To determine the length of warm ischemic tolerance in pulmonary grafts from non-heart-beating donors.

SUMMARY BACKGROUND DATA

If lungs could be retrieved for transplant after circulatory arrest, the shortage of donors might be significantly alleviated. Great concern, however, exists about the length of tolerable warm ischemia before cold preservation of pulmonary grafts retrieved from such non-heart-beating donors.

METHODS

The authors compared the influence of an increasing postmortem interval on graft function in an isolated, room air-ventilated rabbit lung model during blood reperfusion up to 4 hours. Four groups of cadavers (four animals per group) were studied. In group 1, lungs were immediately reperfused. In the other groups, cadavers with lungs deflated were left at room temperature for 1 hour (group 2), 2 hours (group 3), or 4 hours (group 4).

RESULTS

Pulmonary vascular resistance was enhanced in all ischemic groups compared with the control group. An increase was noted with longer postmortem intervals in peak airway pressure and in weight gain. A concomitant decline was observed in the venoarterial oxygen pressure gradient caused by progressive edema formation, as reflected by the wet-to-dry weight ratio at the end of reperfusion.

CONCLUSIONS

Warm ischemia resulted in increased pulmonary vascular resistance. Graft function in lungs retrieved 1 hour after death was not significantly worse than in nonischemic lungs. Therefore, 60 minutes of warm ischemia with the lung collapsed may be tolerated before cold storage. Further studies are necessary to investigate whether lungs retrieved from non-heart-beating donors will become a realistic alternative for transplant.

Prehospital pulseless, unconscious penetrating trauma victims: field assessments associated with survival

BACKGROUND

This study was designed to determine whether out-of-hospital clinical signs could be associated with functional survival for pulseless, unconscious victims of penetrating trauma.

METHODS

A retrospective review of medical data and outcome for pulseless, unconscious penetrating urban trauma victims during 1993-1994. For comparison with the penetrating study group, data for blunt pulseless, unconscious trauma victims for the same period are reported. Logistic regression, odds ratios, positive predictive values, sensitivity, and specificity were used to determine the possible association of field clinical signs with survival.

RESULTS

A total of 879 penetrating and blunt trauma victims met criteria of the study. Four of 497 victims of penetrating injury survived. Three of the four survivors were neurologically intact, with the remaining survivor impaired but functional in a supervised work setting. All survivors of penetrating trauma had monitored cardiac electrical (sinus rhythm or sinus tachycardia) activity on presentation in the field, and three were stabbing victims. Age, total field treatment time, spontaneous respiration, reactive pupils, and return of pulse in the field were not found to be associated with survival. Four victims of penetrating injury survived long enough to donate perfused asystolic-sensitive (kidney, liver, lung, and pancreas) organs. There were 382 victims of blunt injury that met study inclusion criteria with five survivors. None of the five survivors of blunt injury had good neurologic function.

CONCLUSION

Functional survival was rare but did occur with penetrating trauma presenting pulseless and unconscious in the out-of-hospital setting. Although the presence of a pulseless sinus rhythm or tachycardia and stabbing as a mechanism seemed to indicate better survival rates, our study failed to identify reliable out-of-hospital criteria to separate salvageable penetrating trauma victims from those who are nonsalvageable. With this lack of reliable criteria, aggressive prehospital resuscitation efforts and rapid transport to the nearest trauma center for pulseless, unconscious victims of penetrating injury seem indicated.

Intravenous phenylephrine preconditioning of cardiac grafts from non-heart-beating donors

BACKGROUND

Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non-heartbeating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.

METHODS

Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non-heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 microg/kg (n = 7) before initiation of apnea. Non-heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.

RESULTS

Phenylephrine 25 microg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 +/- 0.5 versus 7.7 +/- 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 +/- 5.3 versus 41.0 +/- 3.4 mm Hg; p = 0.04). Phenylephrine 25 microg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).

CONCLUSIONS

Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.

Reanimation: overcoming objections and obstacles to organ retrieval from non-heart-beating cadaver donors

Interest in the retrieval of organs from non-heart-beating cadaver donors has been rekindled by the success of transplantation of solid organs and the insufficient supply of donor organs currently obtained from heart-beating cadaver donors. There are currently two retrieval techniques being evaluated, the in situ cold perfusion approach and the controlled death approach. Both, however, raise ethical concerns. Reanimation is a new method which has been used successfully in animals. We believe this new approach overcomes the ethical objections raised to these other methods.

Controlled reperfusion of cardiac grafts from non-heart-beating donors

BACKGROUND

Hearts harvested from non-heart-beating donors sustain severe injury during procurement and implantation, mandating interventions to preserve their function. We tested the hypothesis that limiting oxygen delivery during initial reperfusion of such hearts would reduce free-radical injury.

METHODS

Rabbits sustained hypoxic arrest after ventilatory withdrawal, followed by 20 minutes of in vivo ischemia. Hearts were excised and reperfused with blood under conditions of high arterial oxygen tension (PaO2) (approximately 400 mm Hg), low PaO2 (approximately 60 to 70 mm Hg), high pressure (80 mm Hg), and low pressure (40 mm Hg), with or without free-radical scavenger infusion. Non-heart-beating donor groups were defined by the initial reperfusion conditions: high PaO2/ high pressure (n = 8), low PaO2/high pressure (n = 7), high PaO2/low pressure (n = 8), low PaO2/low pressure (n = 7), and high PaO2/high pressure/free-radical scavenger infusion (n = 7).

RESULTS

After 45 minutes of reperfusion, low PaO2/ high pressure and high PaO2/low pressure had a significantly higher left ventricular developed pressure (63.6 +/- 5.6 and 63.1 +/- 5.6 mm Hg, respectively) than high PaO2/high pressure (40.9 +/- 4.5 mm Hg; p < 0.0000001 versus both). However, high PaO2/high pressure/free-radical scavenger infusion displayed only a trend toward improved ventricular recovery compared with high PaO2/ high pressure.

CONCLUSIONS

Initially reperfusing nonbeating cardiac grafts at low PaO2 or low pressure improves recovery, but may involve mechanisms other than decreased free-radical injury.

Non-heart-beating donors: a model of thoracic allograft injury

4ACKGROUND. Non-heart-beating donors (NHBDs) have been proposed for the critical shortage of donors for cardiac and pulmonary transplantation. We determined the effects of prearrest hypoxia and postarrest warm ischemia on cardiac and pulmonary allografts procured from NHBDs undergoing hypoxic arrest. METHODS. Rabbit hearts and lungs were procured from separate donors and placed on isolated blood perfusion circuits. Controls were excised and perfused without ischemia. Heart from NHBDs underwent either prearrest hypoxic perfusion alone or consecutive periods of prearrest hypoxic perfusion and 20 minutes of postarrest warm ischemia. A third group of hearts underwent 30 minutes of warm, global ischemia alone. Two groups of pulmonary allografts were studied using similar hypoxic perfusion/20-minute ischemia and 30-minute ischemia donors. RESULTS. Prearrest hypoxic perfusion clearly causes significant dysfunction of cardiac allografts from NHBDs compared with nonischemic controls. Prearrest hypoxic perfusion combined with postarrest ischemia results in an additive degree of dysfunction more severe than a similar period of warm ischemia alone. Both groups of experimental lungs displayed function similar to that of nonischemic controls in terms of pulmonary hemodynamics, airway resistance, and oxygenation potential. CONCLUSIONS. We conclude that prearrest hypoxic perfusion significantly contributes to the dysfunction of NHBD cardiac allografts. Pulmonary allografts may be more amenable to procurement of NHBDs.

Neurologic sequelae of deep hypothermic circulatory arrest in cardiac transplant infants

BACKGROUND

Considerable controversy exists experimentally and clinically regarding adverse neurologic effects that may follow deep hypothermic circulatory arrest. Moreover, the techniques of DHCA have never been standardized.

METHODS

We prospectively studies the neurodevelopmental outcome in 38 infants undergoing cardiac transplantation using DHCA before the age of 4 months (mean age, 37.0 days). Neurodevelopmental outcome in the 22 boys and 16 girls was tested up to 2.5 years after transplantation using Bayley scale of infant development. Bayley scores were compared with the rate of core cooling and the length of DHCA in all patients. Deep hypothermic circulatory arrest was accomplished using an asanguineous prime resulting in hematocrits of 5% +/- 5% and ionized Ca2+, 0.4 +/- 0.1 mmol/L. No surface precooling was used, but the head was packed in ice. Mean cooling time was 14.0 +/- 3.5 minutes, resulting in rectal temperatures of 18 degrees +/- 2.5 degrees C. Duration of DHCA ranged from 42 to 70 minutes (mean duration, 56.0 +/- 6.6 minutes).

RESULTS

Postoperatively, the mean Bayley psychomotor development index was 91 (range, 50 to 130) and mental development index was 88 (range, 50 to 130). No relationship was found between either the rate of cooling or the duration of DHCA and Bayley scores (r = 0.227 and r = 0.322, respectively).

CONCLUSIONS

These data suggest that neither the rate of cooling nor DHCA times between 42 and 70 minutes using profoundly low hematocrits and low ionized calcium levels has any measurable effect on neurologic outcome up to 2.5 years postoperatively. It is possible that adverse neurologic outcomes from DHCA reflect particular methods of achieving DHCA.

Successful survival of primates receiving transplantation with "dead," nonbeating donor hearts

A paucity of donor organs is the principal limitation in human heart transplantation. Prompted by our short-term studies of reanimating "dead" donor hearts in sheep, we applied the same reperfusion modifications in juvenile baboons to determine human applications in an anoxic arrest model (as occurs when non-brain-dead patients are extubated and allowed to die). Ten juvenile baboons (mean weight 3.6 kg) were studied. Five baboons were used as donors. After being anesthetized, donors were pretreated with methylprednisolone (Solu-Medrol), 50% dextrose, nifedipine, and prostaglandin E1 and then paralyzed and extubated. Donors became pulseless at 7 +/- 1 minutes and had electric arrest 9 to 18 minutes after paralysis. The five donors were left undisturbed and warm for 15, 22, 30, 30, and 31 minutes, respectively, after asystole. They were then given 250 ml of 4 degrees C Roe's crystalloid cardioplegic solution via the aortic root and the hearts were explanted into iced Euro-Collins solution. Five baboons served as recipients. After donor harvest, recipients were placed on cardiopulmonary bypass, given prostaglandin E1, and cooled to 18 degrees C; circulatory arrest was instituted and the recipient's heart excised. The donor heart was transplanted in an orthotopic position. Before reinstitution of bypass, 250 ml of terminal leukocyte-depleted blood cardioplegic solution was given, then bypass was restarted and the hearts were reperfused for 60 minutes. All animals were weaned from bypass without the use of inotropic agents. All animals were extubated within 2 to 4 hours after bypass and received standard immunosuppression. Peak creatine kinase MB/total creatine kinase ratio was 0.2% +/- 0.2%. Postoperative ejection fractions by echocardiography were 75% to 80% (mean 76%). Animals survived 1, 9, 13, 16, and 34 days, with three deaths caused by acute rejection and one each by stroke and diarrhea/dehydration. Pathologic findings showed no areas of fibrosis or ischemic damage. We conclude that successful reanimation and engraftment can be achieved with the use of the asystolic primate heart; this work suggests that human application is realistic and could greatly expand the donor pool.