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High B-type natriuretic peptide (BNP) levels are reported in the context of septic shock. We hypothesized that high BNP levels might be related to an alteration in BNP clearance pathway, namely neutral endopeptidase (NEP) 24.11. NEP 24.11 activity was measured in septic shock and in cardiogenic shock patients. We further evaluated whether baseline plasma BNP can predict fluid responsiveness and whether BNP can still be released in plasma despite high initial BNP levels, in response to overloading.Prospective observational study. Patients in severe sepsis (S) or in septic shock (SS) needing a fluid challenge were included. Stroke volume (SV) and BNP were measured before (SV1, BNP1) and 45 mins after (SV2, BNP2) a standardized fluid challenge. DeltaBNP was defined as the difference between BNP2 and BNP1. NEP 24.11 activity was determined by fluorometry in 12 SS and 4 S patients before fluid challenge and in 5 cardiogenic shock patients.Twenty-three patients (61 +/- 18 years old, Simplified Acute Physiology Score II: 54 +/- 21; 19 SS, 4 S; BNP1: 1371 +/- 1434 pg/mL) were studied. BNP1 concentrations were significantly higher in SS than in S (1643 +/- 1437 vs. 80 +/- 35 pg/mL; p = 0.002). There was no correlation between baseline BNP and fluid responsiveness. Nine of the 11 patients with BNP11000 pg/mL were fluid responders. DeltaBNP was greater in fluid nonresponders than in fluid responders (22 +/- 27% vs. 6 +/- 11%, p = 0.028). Plasma BNP was higher in SS than in cardiogenic shock patients (1367 +/- 1438 vs. 750 +/- 346 respectively; p = 0.027). NEP 24.11 activity was lower in SS than in S patients (0.10 +/- 0.06 nmole/mL/min vs. 0.50 +/- 0.22 nmole/mL/min, p0.0001) cardiogenic shock patients (0.10 +/- 0.06 nmole/mL/min vs. 0.58 +/- 0.19 nmole/mL/min; p = 0.002).High levels of BNP might be related to an alteration in BNP clearance. During sepsis, high BNP levels are not predictive of fluid nonresponsiveness. Nevertheless, in fluid nonresponders, acute ventricular stretching can result in further BNP release.

To evaluate the prognostic value of adrenocortical response to corticotropin in septic shock patients operated on exclusively for an intra-abdominal source of infection. Prospective, observational, single-center study in a surgical intensive care unit of a university hospital 118 consecutive septic shock patients undergoing laparotomy or drainage for intra-abdominal infection. Baseline cortisol (t 0) and cortisol response to corticotropin test (Δ) were measured during the first 24 h following onset of shock. The relationship between adrenal function test results and survival was analyzed as well as the effect of etomidate anesthesia. Cortisol plasma level at t 0 was higher in nonsurvivors than in survivors (33 ± 23 vs. 25 ± 14 μg/dl), but the response to corticotropin test did not differ between these two subgroups. ROC analysis showed threshold values for t 0 (32 μg/dl) and Δ (8 μg/dl) that best discriminated survivorsfrom nonsurvivors in our population. We observed no difference in survival at the end of hospital stay using log rank test when patients were separated according to t 0, Δ, or both. In addition, adrenal function testsand survival did not differ in patients who received etomidate anesthesia (n = 69) during the surgical treatment of their abdominal sepsis. In this cohort of patients with abdominal septic shock baseline cortisol level and the response to corticotropin test did not discriminate survivors from nonsurvivors. No deleterious impact of etomidate anesthesia on adrenal function tests and survival was observed in these patients.

Background: An underlying extracellular matrix defect is suspected in patients with spontaneous cervical artery dissection (SCAD). We test the hypothesis that levels of matrix metalloproteinase (MMP) 2 and 9, and elastase, extracellular-matrix-regulating enzymes involved in the vascular wall remodeling process, are modified in SCAD. Methods: The authors prospectively and consecutively recruited 47 patients with SCAD and 52 patients with an ischemic stroke from another cause in 2 centers, and measured their plasmatic level of MMP-2, MMP-9 and elastase 3 months after the vascular event. Results: Patients with SCAD had a higher mean MMP-2 level compared with controls [379.2 (SD = 76.6) vs. 355.9 (75.1) ng/ml; p = 0.11] and had more frequently a high level of MMP-2 (>326 ng/ml) than controls (77.8 vs. 54.5%, p = 0.019). This association was stronger in patients with multiple dissection than single artery dissection or controls (84.6, 75.0 and 54.5%, respectively, p = 0.018). The levels of MMP-9 and elastase were similar in cases and controls, but more patients had a high level of these enzymes in the group with multiple dissections than in the group with single artery dissection or controls. Conclusion: Patients with SCAD have higher plasma levels of proteases, particularly MMP-2. The association is stronger in patients with multiple dissections.

Background Postpartum hemorrhage remains a major cause of global maternal morbidity and mortality, even in developed countries, despite the use of intensive care units. This study sought to (1) assess whether myocardial ischemia could be associated with and even aggravate hemorrhagic shock in young parturients admitted for postpartum hemorrhage, and (2) identify the independent risk factors for myocardial ischemia. Methods On their referral to the intensive care unit, a multidisciplinary team managed parturients with severe postpartum hemorrhage. Ventilation, transfusion, catecholamines, surgery, or angiography with uterine embolization were provided as clinically indicated. Plasma cardiac troponin I levels were used as a surrogate marker of acute myocardial injury and electrocardiograms of myocardial ischemia. Results A total of 55 parturients were referred with severe postpartum hemorrhage, all in hemorrhagic shock. Twenty-eight parturients (51%) had elevated serum levels of cardiac troponin I (9.4 microg/l [3.7-26.6 microg/l]), which were associated with electrocardiographic signs of ischemia and deteriorated myocardial contractility and correlated with the severity of hemorrhagic shock. Indeed, multivariate analysis identified low systolic and diastolic arterial blood pressure (< 88 and < 50 mmHg, respectively) and increased heart rate (> 115 beats/min) as independent predictors of myocardial injury. In addition, all patients who were given catecholamines also had elevated cardiac troponin I levels. Conclusions These results suggest that treatment of postpartum hemorrhage-induced hemorrhagic shock should be coupled with concomitant prevention of myocardial ischemia, even in young parturients.

Cardiac harvest teams are usually committed to immediately transfer the explanted donor heart into its cold storage solution. We tested the opposite hypothesis that a brief prestorage episode of heat-enhanced ischemic preconditioning could be protective.Fifty-three isolated isovolumic rat hearts underwent 4 hours of cold (4 degrees C) storage in the Celsior preservation solution and 2 hours of reperfusion. Control hearts were immediately immersed after arrest. In the 3 treated groups, 2 customized thermal probes were first applied onto the left ventricular free wall of the explanted heart at 22 degrees C, 37 degrees C or 42.5 degrees C for 15 minutes before immersion. Each of the selected temperatures were monitored at the probe-tissue interface by a thermocouple.Whereas base line end-diastolic pressure was set at = 8 mm Hg in all groups, it increased during reperfusion (mean +/- SEM) to 28+/-3, 27+/-3, 17+/-1, and 18+/-2 mm Hg in control, 22 degrees C, 37 degrees C and 42.5 degrees C-heated hearts, respectively (37 degrees C and 42.5 degrees C: p0.05 versus controls and 22 degrees C). Slopes of pressure-volume curves featured similar patterns. Likewise, reperfusion dP/dT (mm Hg/s(-1)) was significantly lower in control and 22 degrees C hearts (1,119+/-114 and 1,076+/-125, respectively) than in those undergoing prestorage heating to 37 degrees C and 42.5 degrees C (1,545+/-109 and 1,719+/-111, p0.05 and p0.01 versus controls and 22 degrees C, respectively). Western blot analysis of LV samples did not demonstrate any upregulation of HSP 72 in either group. Conversely, the involvement of preconditioning was evidenced by the loss of protection in the 42.5 degrees C-heated hearts when, in 2 additional groups, the storage solution was supplemented with either the protein kinase C and tyrosine kinase inhibitors chelerythrine (5 micromol/L) and genistein (50 micromol/L) or the mitochondrial K(ATP) channel inhibitor 5-hydroxydecanoate (200 micromol/L).A brief period of postexplant ischemia with enhancement by topical heating ("backtable preconditioning") could be a simple and effective means of improving the functional recovery of heart transplants.

Ischemic preconditioning is an effective means of reducing myocardial infarct size, but its ability to attenuate stunning after an episode of surgically relevant global ischemia remains elusive. Likewise, the role played by adenosine in this setting has not been established conclusively. This study was designed to address these two issues.Thirty isolated, crystalloid-perfused rabbit hearts were subjected to 60 minutes of normothermic potassium arrest and 60 minutes of reperfusion. They were divided into three equal groups. The first group had no prearrest intervention and served as a control. In the second group, ischemic preconditioning was achieved with 5 minutes of zero-flow ischemia followed by 5 minutes of buffer reperfusion before arrest. In the third group, the hearts were first infused for 5 minutes with the nucleoside transport inhibitor draflazine (10(-6) mol/L), the efficacy of which was demonstrated by reversal of the normally high inosine to adenosine ratio in the coronary effluent. These hearts subsequently were given 2 additional minutes of ischemic (zero-flow) preconditioning followed by 5 minutes of reperfusion before arrest. During reperfusion, function was measured serially under isovolumic conditions. Myocardial necrosis was estimated from the release of creatine kinase after the initial 5 minutes of reflow, and the planimetrically determined extent of infarction was determined by triphenyltetrazolium chloride staining.Baseline hemodynamic data were comparable among the three groups. Neither ischemic preconditioning alone nor ischemic preconditioning with draflazine-induced enhancement of endogenous adenosine levels improved postischemic recovery of function over that seen in control, untreated hearts. These results correlated with a minimal amount of infarction in the control group (on average,10% of the left ventricle), which was not reduced further by either preconditioning regimen.These data support the idea that, in the absence of substantial necrosis, ischemic preconditioning does not ameliorate postischemic stunning, which leads to the question of its usefulness in clinical cardiac operations. Although, in this model, protection was not potentiated by increasing endogenous concentrations of adenosine, it remains a worthwhile goal to identify the final effectors of the signaling pathway accounting for the otherwise demonstrated cardioprotective effects of preconditioning because of the potential for these mediators to act as effective antiischemic agents.

Objective: Ischemic preconditioning is now established as an effective means of reducing infarct size. However, it remains uncertain whether preconditioning can improve the myocardial protection afforded by cardioplegia. The present study was designed to address this issue. Methods: After the institution of cardiopulmonary bypass, 10 patients were preconditioned with 3 minutes of aortic crossclamping followed by 2 minutes of reperfusion before the onset of retrograde continuous warm cardioplegic arrest. Ten case-matched patients served as controls. Three blood samples were drawn simultaneously from the radial artery and the coronary sinus before bypass, at the end of the 5-minute preconditioning protocol or after 5 minutes of bypass in control patients, and at the end of cardioplegic arrest. These samples were assayed for creatine kinase MB isoenzyme and lactate. Right atrial biopsy specimens taken at the same time points were processed by Northern blotting for the expression of messenger ribonucleic acid of both c- fos and heat shock protein 70. Results: At the end of arrest, the release of creatine kinase MB from the myocardium was markedly greater in preconditioned patients than in the controls. The transmyocardial lactate gradient was shifted toward production in the preconditioned group (+0.22 ± 0.13 mmol/L) and toward extraction in the control group (-0.06 ± 0.21 mmol/L). Molecular biology data did not suggest a protective effect of preconditioning. There were no clinical adverse events related to preconditioning. Conclusions: Preconditioning does not enhance cardioplegic protection and might even be deleterious. These results do not dismiss its use in cardiac operations. They rather emphasize the need for identifying pharmacologic mediators that could safely and effectively duplicate the cardioprotective effects of ischemic preconditioning. (J THORAC CARDIOVASC SURG 1996;112:1378-86)

The enthusiastic clinical reports on normothermic blood cardioplegia contrast with the paucity of data on the myocirdial metabolic effects of this technique. The present study was therefore designed to assess whether normothermic blood cardioplegia really provides an aerobic environment during aortic cross-clamping. Thirty-one patients undergoing coronary (16 patients), valve (13 patients), and transplantation (2 patients) procedures were given continuous normothermic blood cardioplegia through the coronary sinus. Myocardial metabolism was assessed either immediately before aortic unclamping (16 patients) by collecting blood simultaneously from the cardioplegia infusion line and the aortic effluent or during reperfusion (15 patients) by collecting blood simultaneously from the radial artery and the coronary sinus. All samples were assayed for markers of anaerobiosis (blood gases, lactates), leukocyte activation (elastase), and lipid peroxidation (malondialdehyde, vitamin E). At the end of arrest, oxygen extraction was low, whereas the production of lactates was small, thereby suggesting the efficacy of normothermic blood cardioplegia in maintaining a predominantly aerobic metabolism. This was confirmed by postarrest data, as oxygen extraction measured immediately after cross-clamp removal was unchanged from prearrest values, whereas lactate metabolism yielded transient and limited production followed by prompt recovery of normal extraction patterns. There was no release of elastase from the myocardium, which suggests adequate protection of the coronary endothelium from ischemic injury and the related increase in leukocyte activation. Likewise, postarrest coronary sinus concentrations of malondialdehyde and vitamin E were identical to the respective arterial concentrations, thereby ruling out the occurrence of intramyocardial lipid peroxidation at the time of reperfusion. This absence of oxidative reperfusion injury further supports the idea that no (or minimal) ischemic injury occurred during the preceding cross-clamp period. We conclude that normothermic blood cardioplegia can effectively keep the heart in a predominantly aerobic state during aortic cross-clamping, which makes its use particularly attractive in patients who have limited tolerance to intraoperative myocardial ischemia.

Among the interventions designed to limit postischemic oxidative injury, those that enhance the myocardial content of thiol groups are attractive because thiols are powerful antioxidant. Indeed, part of the protection afforded by the angiotensin-converting enzyme (ACE) inhibitor captopril in regional myocardial ischemia is attributed to its thiol group. This study assesses the effects of captopril in a surgically relevant model of global ischemic arrest. Thirty rats were implanted subcutaneously (s.c.) with osmotic pumps that allowed continuous delivery of captopril (total dose 75 mg), enalapril (a nonthiol-containing ACE inhibitor, total dose 7.5 mg) or saline in 48 h. Drug concentrations were equipotent in their effect on angiotensin I (ANGI) pressor response. Hearts were then excised, perfused under isovolumic conditions, and subjected to 90-min cardioplegic arrest at 30 degrees C followed by 1-h reperfusion. Pre- and postischemic coronary flows were significantly higher to a similar extent in the two drug-pretreated groups than in controls. However, captopril-pretreated hearts had the best recovery of contractility (dP/dtmax; 3,590 +/- 74 versus 2915 +/- 64 mm Hg s-1 in the enalapril group, p less than 0.001), and diastolic pressure (13.7 +/- 0.9 mm Hg vs. 20.0 +/- 1.6 mm Hg in the enalapril group, p less than 0.05). We conclude that pretreatment with ACE inhibitors improves myocardial recovery after cardioplegic arrest and that captopril is more effective than enalapril. The additional protection afforded by captopril was not flow mediated, suggesting that the cardioprotective effects of this drug not only involve an ACE inhibition-dependent coronary vasodilation but could be related to a thiol-dependent limitation of oxidative injury.

Background —Recent studies have implicated mitochondrial ATP-sensitive potassium (K ATP ) channels in the cardioprotective effects of ischemic preconditioning. The present study used a model of prolonged cold heart storage to assess whether the mitochondrial K ATP opener diazoxide could reproduce the protection conferred by ischemic preconditioning. Methods and Results —Fifty-four isolated rat hearts were arrested with and stored in Celsior at 4°C for 10 hours before a 2-hour reperfusion. They were divided into 5 groups. Group 1 hearts served as controls. In group 2, hearts were preconditioned by two 5-minute episodes of global ischemia, each separated by 5 minutes of reperfusion before arrest. In group 3, hearts received a 15-minute infusion of the mitochondrial K ATP opener diazoxide (30 μmol/L) followed by 5 minutes of washout before arrest. In groups 4 and 5, hearts underwent a protocol similar to that used in groups 2 and 3, respectively, except that the preconditioning was preceded by a 10-minute infusion of the mitochondrial K ATP blocker 5-hydroxydecanoate (5-HD, 100 μmol/L). Both ischemic and diazoxide preconditioning provided a similar degree of cardioprotection demonstrated by a significantly better preservation of left ventricular compliance, reduced leakage of creatine kinase, and smaller degree of myocardial edema compared with control hearts. These beneficial effects were abolished by 5-HD pretreatment. Postischemic left ventricular contractility and endothelium-dependent coronary response to 5-hydroxytryptamine and acetylcholine were not different among groups. However, the endothelium-independent vasodilatory postischemic response to papaverine was better preserved after ischemic and diazoxide preconditioning than in the other groups. Conclusions —These data support the concept that the cardioprotective effects of ischemic preconditioning can be duplicated by a mitochondrial K ATP opener and suggest that activation of these channels could be an effective means of improving the preservation of globally ischemic cold-stored hearts, as occurs during cardiac transplantation.

Background —Experimentally, isoflurane, a commonly used volatile anesthetic agent, mimics the cardioprotective effects of ischemic preconditioning via a mechanism that could involve the activation of protein kinase C. The present study was designed to assess the clinical relevance of this observation in patients undergoing elective CABG. Methods and Results —Twenty patients were included in the study. In 10 of them, preconditioning was elicited after the onset of cardiopulmonary bypass via a 5-minute exposure to isoflurane (2.5 minimum alveolar concentration), followed by a 10-minute washout before aortic cross-clamping and cardioplegic arrest. Ten case-matched control patients underwent an equivalent period (15 minutes) of prearrest isoflurane-free bypass. Outcome measurements included troponin I and creatine kinase–MB isoenzyme (until the third postoperative day) levels and the activity of ecto-5′-nucleotidase, which contributes to adenosine production and is considered to be a reporter of protein kinase C activation, as assessed in right atrial biopsy samples taken before bypass and at the end of the preconditioning protocol (or after 15 minutes of bypass in control patients). Aortic cross-clamping times did not differ between the 2 groups: 52±14 and 48±14 minutes (mean±SD) in control and isoflurane-preconditioned patients, respectively. Likewise, prebypass values of ecto-5′-nucleotidase were similar in control (3.54±0.86 nmol · mg protein −1 · min −1 ) and isoflurane-treated (2.98±1.08 nmol · mg protein −1 · min −1 ) patients. The values subsequently remained unchanged in control patients (3.62±0.94 nmol · mg protein −1 · min −1 ), whereas they significantly increased after isoflurane preconditioning (4.74±0.50 nmol · mg protein −1 · min −1 ; P P −1 · min −1 and 3.98±2.83 ng/mL, respectively, versus 284±136 ng · mL −1 · min −1 and 5.88±3.64 ng/mL, respectively, in control patients. The release of creatine kinase–MB featured a similar pattern. There were no adverse effects related to isoflurane. Conclusions —These data support a cardioprotective effect of isoflurane and, more generally, demonstrate the feasibility of pharmacologically preconditioning the human heart during cardiac surgery.

Background —The tolerance of hibernating mammals to cold hypoxia is related to a factor similar to agonists of δ-opioid receptors. This study was designed to assess whether activation of these receptors could reproduce the protection conferred by ischemic preconditioning and whether such cardioprotection was similarly mediated by an opening of ATP-sensitive potassium (K ATP ) channels. Methods and Results —Thirty-two isolated rat hearts were arrested with and stored in Celsior at 4°C for 5 hours before being reperfused for 2 hours. They were divided into 4 equal groups. Group 1 hearts served as controls. In group 2, ischemic preconditioning was elicited by two 5-minute global ischemia periods interspersed with 5 minutes of reperfusion before arrest. In group 3, hearts were pharmacologically preconditioned with a 15-minute infusion of the δ-opioid receptor agonist d -Ala2- d -Leu5-enkephalin (DADLE; 200 μmol/L). In group 4, the protocol was similar to group 3 except that infusion of DADLE was preceded by infusion of the K ATP blocker glibenclamide (50 μmol/L). The salutary effects of both forms of preconditioning were primarily manifest as a better preservation of diastolic function, a reduced myocardial edema, and reduced creatine kinase leakage. This protection was abolished by administration of glibenclamide before DADLE. Conclusions —These data suggest that activation of δ-opioid receptors improves recovery of cold-stored hearts to a similar extent as ischemic preconditioning, most likely through an opening of K ATP channels. This provides a rationale for improving the preservation of hearts for transplantation by pharmacologically duplicating the common pathway to natural hibernation and preconditioning.

Current cardioplegic techniques do not consistently avoid myocardial ischemic damage in high-risk patients undergoing coronary artery bypass grafting. Alternatively, revascularization without cardiopulmonary bypass is not always technically feasible. We investigated whether an intermediary approach based on maintenance of a beating heart with cardiopulmonary bypass support but without aortic cross-clamping might be an acceptable trade-off.Thirty-seven consecutive patients underwent coronary artery bypass grafting (with an average of two grafts per patient) in a pump-supported, non-cross-clamped beating heart. Inclusion criteria were poor left ventricular function (18 patients; mean ejection fraction, 0.25), evolving myocardial ischemia or infarction (11 patients, 5 of whom were in cardiogenic shock), and advanced age (3 patients; mean age 79.5 years) with comorbidities. Results were assessed primarily on the basis of clinical outcome. In addition, measurements of plasma levels of markers of myocardial damage (troponin Ic) and systemic inflammation (interleukin-6, interleukin-10, elastase) were done in 9 patients before and after bypass. In 6 patients, right atrial biopsy specimens were taken before and after bypass and processed by Northern blotting for the expression of messenger ribonucleic acid coding for the cardioprotective heat-shock protein 70. These biologic data were compared with those from control patients who underwent warm cardioplegic arrest within the same time span.There was one cardiac-related death (2.7%), one Q-wave myocardial infarction, and no strokes. Four other deaths occurred from noncardiac causes, yielding an overall mortality rate of 13.5%. Limitation of myocardial injury was demonstrated by the minimal increase in postoperative troponin Ic levels (3.3 +/- 1.0 micrograms/L versus 6.6 +/- 1.5 micrograms/L in controls; p0.05) and the finding that heat-shock protein 70 messenger ribonucleic acid levels (expressed as a percentage of an internal standard) were significantly increased after bypass compared with pre-bypass values (279% +/- 80% versus 97% +/- 21%; p0.05). In the control group (cardioplegia), end-arrest values of heat-shock protein 70 messenger ribonucleic acid were not significantly changed from baseline (148% +/- 49% versus 91% +/- 29%), a finding suggesting a defective adaptive response to surgical stress. Conversely, peak levels of inflammatory mediators were not significantly different between the two groups. The eight grafts to the left anterior descending coronary artery that were assessed angiographically, by transthoracic Doppler echocardiography, or both methods were patent with satisfactory anastomoses.In select high-risk patients, on-pump, beating-heart coronary artery bypass grafting may be an acceptable trade-off between conventional cardioplegia and off-pump operations. It is still associated with the potentially detrimental effects of cardiopulmonary bypass but eliminates intraoperative global myocardial ischemia.

Abstract Pericardial fluid (PF) may contain myocardial growth factors that exert paracrine actions on cardiac myocytes. The aims of this study were (1) to investigate the effects of human PF and serum, collected from patients undergoing cardiac surgery, on the growth of cultured adult rat cardiac myocytes and (2) to relate the growth activity of both fluids to the adaptive changes in overloaded human hearts. Both PF and serum increased the rate of protein synthesis, measured by [ 14 C]phenylalanine incorporation in adult rat cardiomyocytes (PF, +71.9±8.2% [n=17]; serum, +14.9±6.5% [n=13]; both P P

In the course of cardiac transplantation, donor hearts undergo a four-step sequence of events (arrest, cold storage, global ischemia during implantation, and reperfusion) during which myocardial damage can occur. We tested the hypothesis that the functional recovery of these hearts could be improved by exposure to two interdependently formulated preservation solutions throughout this four-step sequence. Solution I was used as a perfusion and storage medium during the first three steps, and solution II served as a modified reperfusate. The two solutions share the following principles of formulation: prevention of cell swelling (high concentrations of mannitol, a myocardium-specific impermeant) calcium overload (ionic manipulations), and oxidative damage (reduced glutathione) and enhancement of anaerobic energy production (glutamate). The two solutions differ with respect to the calcium content and buffering capacity. One hundred rat hearts perfused with isolated isovolumic buffer were subjected to cardioplegic arrest; cold (2 degrees C) storage for 5 hours, global ischemia at 15 degrees C for 1 hour, and normothermic reperfusion for 1 additional hour. In a first series of experiments (70 hearts), our kit of solutions was compared with six clinical preservation regimens that involved cardiac arrest with St. Thomas' Hospital or University of Wisconsin solutions followed by storage of the hearts in saline, Euro-Collins, St. Thomas' Hospital, or University of Wisconsin solutions. In a second series of experiments (30 hearts), the effects of the kit were more specifically investigated in relation to two types of additive--oncotic agents (dextran) and thiol-based antioxidants (reduced glutathione and N-acetyl-L-cysteine). According to comparisons of maximal rate of ventricular pressure increase and left ventricular compliance after reperfusion, the best myocardial protection was afforded by our kit of solutions. The addition of dextran during storage did not provide additional protection. Conversely, the omission of reduced glutathione was clearly detrimental; the replacement of reduced glutathione with N-acetyl-L-cysteine failed to improve recovery beyond that provided by antioxidant-free solutions, thereby suggesting the importance, in this model, of an anti-free radical compound that, like reduced glutathione, is operative extracellularly. We conclude that the preservation of heart transplants can be improved with the sequential use of two closely interrelated solutions, the formulations of which integrate the basic principles of organ preservation with those of myocardium-specific metabolism.