Cerebral injury after cardiac surgery: identification of a group at extraordinary risk. Multicenter Study of Perioperative Ischemia Research Group (McSPI) and the Ischemia Research Education Foundation (IREF) Investigators.

BACKGROUND AND PURPOSE: Cerebral injury after cardiac surgery is now recognized as a serious and costly healthcare problem mandating immediate attention. To effect solution, those subgroups of patients at greatest risk must be identified, thereby allowing efficient implementation of new clinical strategies. No such subgroup has been identified; however, patients undergoing intracardiac surgery are thought to be at high risk, but comprehensive data regarding specific risk, impact on cost, and discharge disposition are not available. METHODS: We prospectively studied 273 patients enrolled from 24 diverse US medical centers, who were undergoing intracardiac and coronary artery surgery. Patient data were collected using standardized methods and included clinical, historical, specialized testing, neurological outcome and autopsy data, and measures of resource utilization. Adverse outcomes were defined a priori and determined after database closure by a blinded independent panel. Stepwise logistic regression models were developed to estimate the relative risks associated with clinical history and intraoperative and postoperative events. RESULTS: Adverse cerebral outcomes occurred in 16% of patients (43/273), being nearly equally divided between type I outcomes (8.4%; 5 cerebral deaths, 16 nonfatal strokes, and 2 new TIAs) and type II outcomes (7.3%; 17 new intellectual deterioration persisting at hospital discharge and 3 newly diagnosed seizures). Associated resource utilization was significantly increased--prolonging median intensive care unit stay from 3 days (no adverse cerebral outcome) to 8 days (type I; P<0.001) and from 3 to 6 days (type II; P<0.001), and increasing hospitalization by 50% (type II, P=0.04) to 100% (type I, P<0.001). Furthermore, specialized care after hospital discharge was frequently necessary in those with type I outcomes, in that only 31% returned home compared with 85% of patients without cerebral complications (P<0.001). Significant risk factors for type I outcomes related primarily to embolic phenomena, including proximal aortic atherosclerosis, intracardiac thrombus, and intermittent clamping of the aorta during surgery. For type II outcomes, risk factors again included proximal aortic atherosclerosis, as well as a preoperative history of endocarditis, alcohol abuse, perioperative dysrhythmia or poorly controlled hypertension, and the development of a low-output state after cardiopulmonary bypass. CONCLUSIONS: These prospective multicenter findings demonstrate that patients undergoing intracardiac surgery combined with coronary revascularization are at formidable risk, in that 1 in 6 will develop cerebral complications that are frequently costly and devastating. Thus, new strategies for perioperative management--including technical and pharmacological interventions--are now mandated for this subgroup of cardiac surgery patients.

Hematocrit value on intensive care unit entry influences the frequency of Q-wave myocardial infarction after coronary artery bypass grafting. The Institutions of the Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

OBJECTIVES: No data exist regarding "the best" hematocrit value after coronary artery bypass graft surgery. Transfusion practice varies, because neither an optimal hematocrit value nor a uniform transfusion trigger criterion has been determined. METHODS: To investigate the optimal hematocrit value, we studied 2202 patients undergoing coronary bypass. The hematocrit value on entry into the intensive care unit (IHCT) was categorized into three groups: high (> or = 34%), medium (25% to 33%), and low (< or = 24%). Characteristics and adverse events (outcomes) were compared, and the effect of IHCT on the risk of myocardial infarction was determined by logistic regression. RESULTS: High IHCT (> or = 34%) was associated with an increased rate of myocardial infarction (8.3% vs 5.5% vs 3.6%; p < or = 0.03, high, medium vs low) and with more severe left ventricular dysfunction (11.7% vs 7.4% and 5.7%; p=0.006, high, medium vs low). Mortality rate increased with higher IHCT when all the high-risk subgroups were combined (8.6% vs 4.5% vs 3.2%; p < 0.001, high, medium vs low). By multivariate analysis, IHCT remained the most significant predictor of adverse outcomes (relative risk high vs low 2.22, 95% confidence interval: 1.04 to 4.76). No characteristic, event, medication, or transfusion therapy confounded the relationship between IHCT and outcome. CONCLUSION: High IHCT is associated with a higher rate of myocardial infarction and is an independent predictor of infarction. On the basis of the risk of myocardial infarction, there is no rationale for transfusion to an arbitrary level after coronary artery bypass grafting.

The concordance of intraoperative left ventricular wall-motion abnormalities and electrocardiographic S-T segment changes: association with outcome after coronary revascularization. Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

BACKGROUND: Transesophageal echocardiography (TEE) and Holter electrocardiography (ECG) are used to detect intraoperative ischemia during coronary artery bypass graft surgery (CABG). Concordance of these modalities and sensitivity as indicators of adverse perioperative cardiac outcomes are poorly defined. The authors tried to determine whether routine use of Holter ECG and TEE in patients with CABGs has clinical value in identifying those patients in whom myocardial infarction (MI) is likely to develop. METHODS: A total of 351 patients with CABG and both ECG- and TEE-evaluable data were examined for the occurrence of ischemia and infarction. The TEE and five-lead Holter ECGs were performed continuously during cardiac surgery. The incidence of MI (creatine kinase-MB > or = 100 ng/ml) within 12 h of arrival in the intensive care [ICU] unit, new ECG Q wave on ICU admission or on the morning of postoperative day 1, or both, were recorded. RESULTS: Electrocardiographic or TEE evidence of intraoperative ischemia was present in 126 (36%) patients. The concordance between modalities was poor (positive concordance = 17%; Kappa statistic = 0.13). Myocardial infarction occurred in 62 (17%) patients, and 32 (52%) of them had previous intraoperative ischemia. Of these, 28 (88%) were identified by TEE, whereas 13 (41%) were identified by ECG. Prediction of MI was greater for TEE compared with ECG. CONCLUSIONS: Wall-motion abnormalities detected by TEE are more common than S-T segment changes detected by ECG, and concordance between the two modalities is low. One half of patients with MI had preceding ECG or TEE ischemia. Logistic regression revealed that TEE is twice as predictive as ECG in identifying patients who have MI.

Renal dysfunction after myocardial revascularization: risk factors, adverse outcomes, and hospital resource utilization. The Multicenter Study of Perioperative Ischemia Research Group.

BACKGROUND: Acute changes in renal function after elective coronary bypass surgery are incompletely characterized and represent a challenging clinical problem. OBJECTIVE: To determine the incidence and characteristics of postoperative renal dysfunction and failure, perioperative predictors of dysfunction, and the effect of renal dysfunction and failure on in-hospital resource utilization and patient disposition after discharge. DESIGN: Prospective, observational, multicenter study. SETTING: 24 university hospitals. PATIENTS: 2222 patients having myocardial revascularization with or without concurrent valvular surgery. MEASUREMENTS: Prospective histories, physical examinations, and electrocardiographic and laboratory studies. The main outcome measure was renal dysfunction (defined as a postoperative serum creatinine level > or = 177 mumol/L with a preoperative-to-postoperative increase > or = 62 mumol/L). RESULTS: 171 patients (7.7%) had postoperative renal dysfunction; 30 of these (1.4% overall) had oliguric renal failure that required dialysis. In-hospital mortality, length of stay in the intensive care unit, and hospitalization were significantly increased in patients who had renal failure and those who had renal dysfunction compared with those who had neither (mortality: 63%, 19%, and 0.9%; intensive care unit stay: 14.9 days, 6.5 days, and 3.1 days; hospitalization: 28.8 days, 18.2 days, and 10.6 days, respectively). Patients with renal dysfunction were three times as likely to be discharged to an extended-care facility. Multivariable analysis identified five independent preoperative predictors of renal dysfunction: age 70 to 79 years (relative risk [RR], 1.6 [95% CI, 1.1 to 2.3]) or age 80 to 95 years (RR, 3.5 [CI, 1.9 to 6.3]); congestive heart failure (RR, 1.8 [CI, 1.3 to 2.6]); previous myocardial revascularization (RR, 1.8 [CI, 1.2 to 2.7]); type 1 diabetes mellitus (RR, 1.8 [CI, 1.1 to 3.0]) or preoperative serum glucose levels exceeding 16.6 mmol/L (RR, 3.7 [CI, 1.7 to 7.8]); and preoperative serum creatinine levels of 124 to 177 mumol/L (RR, 2.3 [CI, 1.6 to 3.4]). Independent perioperative factors that exacerbated risk were cardiopulmonary bypass lasting 3 or mor hours and three measures of ventricular dysfunction. CONCLUSIONS: Many patients having elective myocardial revascularization develop postoperative renal dysfunction and failure, which are associated with prolonged intensive care unit and hospital stays, significant increases in mortality, and greater need for specialized long-term care. Resources should be redirected to mitigate renal injury in high-risk patients.

Apoptosis of mononuclear cell infiltrates in cardiac allograft biopsy specimens questions studies of biopsy-cultured cells.

During acute rejection, CD4 and CD8 T cells infiltrate the myocardium and cause myocyte death and dropout. CD4 and CD8 cells use a number of cytotoxic mechanisms, including fas-fas ligand interactions, which lead to apoptotic death. Since fas is expressed on myocytes, we investigated endomyocardial biopsy specimens from cardiac transplant patients to determine whether apoptosis is one of the mechanisms of cell death in acute rejection. Serial sections of individual endomyocardial biopsy specimens from patients histologically diagnosed as having grade 3A rejection (n=22 biopsy specimens), biopsy specimens showing a typical "Quilty effect" (n=10), and specimens with concurrent grade 3A rejection and the Quilty effect (n=6) were evaluated using the C-terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) technique for frequency of apoptosis in myocytes and mononuclear cell infiltrates. None of the examined sections showed detectable evidence of apoptotic myocytes, even within regions clearly showing myocyte damage. Of interest was our consistent finding that 85-98% of mononuclear cell infiltrates within biopsy specimens scored as having grade 3A rejection had undergone apoptosis. In marked contrast, 9 of the 10 specimens with Quilty lesions showed <5% apoptotic mononuclear cells in the endomyocardial infiltrates. Of further interest was our finding of 85-98% apoptotic mononuclear cell infiltrates within Quilty lesions associated with biopsy specimens scored as having grade 3A rejection. The frequency of apoptotic cells determined by the TUNEL technique was confirmed by histological examination of the morphology of the cells and with a technique that involves detection of c-jun. These results prompt a note of caution in the interpretation of data on the phenotype, cytokine profile, Vbeta T cell receptor repertoire, and donor specificity of mononuclear cells cultured and propagated from such cardiac biopsy specimens. The possible reasons for apoptosis of graft-infiltrating mononuclear cells are discussed.

Urine and plasma catecholamine and cortisol concentrations after myocardial revascularization. Modulation by continuous sedation. Multicenter Study of Perioperative Ischemia (McSPI) Research Group, and the Ischemia Research and Education Foundation (IREF).

BACKGROUND: Cardiopulmonary bypass is associated with substantial release of catecholamines and cortisol for 12 or more h. A technique was assessed that may mitigate the responses with continuous 12-h postoperative sedation using propofol. METHODS: One hundred twenty-one patients having primary elective cardiopulmonary bypass graft (CABG) surgery were enrolled in a double-blind, randomized trial and anesthetized using a standardized sufentanil-midazolam regimen. When arriving at the intensive care unit (ICU), patients were randomly assigned to either group SC (standard care), in which intermittent bolus administration of midazolam and morphine were given as required to keep patients comfortable; or group CP (continuous propofol), in which 12 h of continuous postoperative infusion of propofol was titrated to keep patients deeply sedated. Serial perioperative measurements of plasma and urine cortisol, epinephrine, norepinephrine, and dopamine were obtained; heart rate and blood pressure were recorded continuously, and medication use, including requirements for opioids and vasoactive drugs, was recorded. Repeated-measures analysis was used to assess differences between study groups for plasma catecholamine and cortisol levels at each measurement time. RESULTS: In the control state-before the initiation of postoperative sedation in the ICU-no significant differences between study groups were observed for urine or plasma catecholamine or cortisol concentrations. During the ICU study period, for the first 6-8 h, significant differences were found between study groups SC and CP in plasma cortisol (SC = 28 +/- 15 mg/dl; CP = 19 +/- 12 mg/dl; estimated mean difference [EMD] = 9 mg/dl; P = 0.0004), plasma epinephrine (SC = 132 +/- 120 micrograms/ml; CP = 77 +/- 122 micrograms/ml; EMD = 69 micrograms/ml; P = 0.009), urine cortisol (SC = 216 +/- 313 micrograms/ml; CP = 93 +/- 129 micrograms/ml; EMD = 127 micrograms/ml; P = 0.007), urine dopamine (SC = 85 +/- 48 micrograms; CP = 52 +/- 43 micrograms; EMD = 32 micrograms; P = 0.002), urine epinephrine (SC = 7 +/- 8 micrograms; CP = 4 +/- 5 micrograms; EMD = 3 micrograms; P = 0.0009), and urine norepinephrine (SC = 24 +/- 14 mg; CP = 13 +/- 9 mg; EMD = 11 mg; P = 0.0004). Reductions in urine and plasma catecholamine and cortisol concentrations found for the CP group generally persisted during the 12-h propofol infusion period and then rapidly returned toward control (SC group) values after propofol was discontinued. Postoperative opioid use was reduced in the CP group (SC = 97%; CP = 49%; P = 0.001), as was the incidence of tachycardia (SC = 79%; CP = 60%; P = 0.04) and hypertension (SC = 58%; CP = 33%; P = 0.01), but the incidence of hypotension was increased (SC = 49%; CP = 81%; P = 0.001). CONCLUSIONS: Cardiopulmonary bypass graft surgery is associated with substantial increases in plasma and urine catecholamine and cortisol concentrations, which persist for 12 or more h. This hormonal response may be mitigated by a technique of intensive continuous 12-h postoperative sedation with propofol, which is associated with a decrease in tachycardia and hypertension and an increase in hypotension.

Human immunodeficiency virus infection and infective endocarditis among injecting drug users.

Human immunodeficiency virus (HIV) infection and infective endocarditis are serious complications of injection drug use. To determine whether HIV infection may increase the risk of endocarditis beyond that associated with drug injection, we performed a nested case-control study among injecting drug users taking part in an ongoing cohort. We identified 26 participants with infective endocarditis between cohort enrollment (in 1988-1989) and June 1992, through reviews of medical records and death certificates. We matched each endocarditis case with up to five controls (N = 120) on enrollment date, race/ethnicity, and follow-up time. Data were taken from baseline and from the one follow-up visit: the last visit before the endocarditis occurred for cases and the closest visit (+/- 3 months) for controls. We used conditional logistic regression to quantify the association between HIV serostatus at follow-up and subsequent endocarditis, after adjusting for a history of endocarditis or sepsis before enrollment, injection duration, current injection frequency, and a recent history of abscess at injection sites. Among current injectors at follow-up, the adjusted odds ratio (OR) of developing endocarditis for HIV-seropositive subjects with > or = 350 CD4 cells per microliter, compared with HIV-seronegative subjects, was 2.31 [95% confidence interval (CI) = 0.61-8.78]; the corresponding OR for HIV-seropositive subjects with < 350 CD4 cells per microliter was 8.31 (95% CI = 1.23-56.37). These data indicate that HIV-related immunodeficiency may independently increase the risk of infective endocarditis among injecting drug users.

Multicenter preoperative stroke risk index for patients undergoing coronary artery bypass graft surgery. Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

BACKGROUND: The paradox of present cardiac surgery is that the more elderly and debilitated patients benefit most from cardiac surgery compared with medical therapy, yet they sustain greater overall risk for morbidity and mortality after cardiac surgery. The goal of the present study was to develop a preoperative index predicting major perioperative neurological events in patients undergoing coronary artery bypass graft surgery. METHODS AND RESULTS: As part of a prospective, multicenter, observational study (McSPI Research Group), we enrolled 2417 patients at 24 academic medical centers in the United States. Patients who died intraoperatively or had concomitant open-heart procedures were excluded from analysis, resulting in a total of 2107 for analysis. Sixty-eight patients (3.2%) developed adverse neurological events, defined as cerebrovascular accident, transient ischemic attack (TIA), or persistent coma. Bivariate analysis was applied to determine associations between preoperative variables and neurological events. Significant bivariate predictors were identified then logically grouped, and for each cluster, a score was calculated based on principal components. Key predictor variables were age, history of previous neurological disease, diabetes, history of vascular disease, previous coronary artery surgery, unstable angina, and history of pulmonary disease, the coefficients for which were used to develop a preoperative stroke risk index that was validated by bootstrap (c-index = 0.778). Stroke risk could then be determined for each patient, calculating a patient's risk for stroke within 95% confidence intervals. CONCLUSIONS: With the McSPI stroke risk index developed in this study, neurological risk can be estimated, and the most appropriate group for perioperative therapy can be identified. Further refinement and validation of this index, however, are necessary and are under way in current studies.

Cardiomyopathy and other symptomatic heart diseases associated with HIV infection.

Approximately 14 million persons worldwide are estimated to be infected with HIV-1. As more effective therapies have produced longer survival times for HIV-infected patients, new complications of late-stage HIV infection including HIV-related heart disease have emerged. The most common and life-threatening cardiovascular complication of HIV infection is the development of primary heart muscle disease associated with severe global left ventricular dysfunction (also termed cardiomyopathy). Other less common forms of symptomatic heart disease in HIV-1-infected patients are pericardial effusion with cardiac tamponade, high-grade arrhythmia with sudden cardiac death, and systemic embolization caused by nonbacterial thrombotic endocarditis or infective carditis. The demographic and clinical characteristics of HIV-infected patients who develop cardiomyopathy as well as potential enhancing risk factors are as yet poorly characterized. This review briefly describes the various presentations and potential causes of symptomatic HIV-related heart disease and discusses the challenge facing clinicians who evaluate HIV-infected patients presenting with serious cardiac manifestations of their disease.

Nitric oxide inhibits viral replication in murine myocarditis.

Nitric oxide (NO) is a radical molecule that not only serves as a vasodilator and neurotransmitter but also acts as a cytotoxic effector molecule of the immune system. The inducible enzyme making NO, inducible NO synthase (iNOS), is transcriptionally activated by IFN-gamma and TNF-alpha, cytokines which are produced during viral infection. We show that iNOS is induced in mice infected with the Coxsackie B3 virus. Macrophages expressing iNOS are identified in the hearts and spleens of infected animals with an antibody raised against iNOS. Infected mice have increased titers of virus and a higher mortality when fed NOS inhibitors. Thus, viral infection induces iNOS in vivo, and NO inhibits viral replication. NO is a novel, nonspecific immune defense against viruses in vivo.

The Myocarditis Treatment Trial: design, methods and patients enrollment.

The Myocarditis Treatment Trial was a multicentre clinical trial conducted to determine the efficacy of immunosuppressive therapy for treatment of biopsy-documented myocarditis, and to improve understanding of the immunological mechanisms in the development of myocarditis. Thirty-one centres screened 2305 patients with unexplained heart failure, and 2233 patients underwent an endomyocardial biopsy which provided adequate tissue for diagnosis. Those with a positive biopsy and a left ventricular ejection fraction (LVEF) less than 45% were randomly assigned to receive immunosuppressive therapy plus conventional drug therapy for congestive heart failure (66 patients) or conventional therapy only (45 patients) for 24 weeks. For 28 additional weeks all patients received conventional therapy only. In addition to diagnostic and clinical data, serum and myocardial tissue for immunological marker analysis and histopathologic evaluation were collected at baseline and at 12, 28 and 52 weeks after randomization. The primary analysis of efficacy was designed as a comparison of the mean increase in LVEF at week 28 between treatment limbs. Secondary objectives were to evaluate survival differences, and changes in the histopathology of the disease and immunological markers. Randomized patients were relatively young (mean age, 42.0 years +/- 13.8 standard deviation (sd) and entered the Trial with a mean LVEF percent of 24.3 +/- 10.1 sd) and mean exercise treadmill duration of 9.4 (+/- 5.3 sd) minutes. The incidence of biopsy-documented myocarditis was low (9.6%). The analyses of outcome and immunological data are reported elsewhere.

Dilated heart muscle disease associated with HIV infection.

As more effective therapies have produced longer survival times for HIV-infected patients, non-infectious complications of late stage HIV infection such as the development of severe global left ventricular dysfunction (dilated heart muscle disease) have emerged. The demographic and clinical characteristics of HIV-infected patients who develop dilated heart muscle disease as well as potential risk factors are, as yet, poorly characterized. Of 174 patients enrolled in a prospective longitudinal study, a total of nine patients, all with CD4 T cell counts < 200 mm-3, developed symptomatic heart disease (congestive heart failure n = 7, sudden cardiac death n = 1 and cardiac tamponade n = 1); three of these patients developed progressive cardiac dysfunction leading to primary cardiac failure and death. An additional 55 HIV-infected patients referred to our Cardiomyopathy Service were found to have global left ventricular dysfunction, with 84% having New York Heart Association Class III or IV congestive heart failure on presentation. Clinical characteristics associated with severe symptomatic cardiac dysfunction included low CD4 T cell counts, myocarditis associated with non-permissive cardiotropic virus infection on endomyocardial biopsy and persistent elevation of anti-heart antibodies. No relationships to any specific HIV risk factor or opportunistic infection were found. These findings suggest that a severe form of HIV-related dilated heart muscle disease is largely a disease of late stage HIV infection. Virus-related myocarditis and cardiac autoimmunity may play a role in the pathogenesis of progressive cardiac injury. Long-term longitudinal studies of larger HIV-infected cohorts are warranted to identify clinical, behavioral and immunologic risk factors.

A clinical trial of immunosuppressive therapy for myocarditis. The Myocarditis Treatment Trial Investigators.

BACKGROUND: Myocarditis is a serious disorder, and treatment options are limited. This trial was designed to determine whether immunosuppressive therapy improves left ventricular function in patients with myocarditis and to examine measures of the immune response as predictors of the severity and outcome of disease. METHODS: We randomly assigned 111 patients with a histopathological diagnosis of myocarditis and a left ventricular ejection fraction of less than 0.45 to receive conventional therapy alone or combined with a 24-week regimen of immunosuppressive therapy. Immunosuppressive therapy consisted of prednisone with either cyclosporine or azathioprine. The primary outcome measure was a change in the left ventricular ejection fraction at 28 weeks. RESULTS: In the group as a whole, the mean (+/- SE) left ventricular ejection fraction improved from 0.25 +/- 0.01 at base line to 0.34 +/- 0.02 at 28 weeks (P < 0.001). The mean change in the left ventricular ejection fraction at 28 weeks did not differ significantly between the group of patients who received immunosuppressive therapy (a gain of 0.10; 95 percent confidence interval, 0.07 to 0.12) and the control group (a gain of 0.07; 95 percent confidence interval, 0.03 to 0.12). A higher left ventricular ejection fraction at base line, less intensive conventional drug therapy at base line, and a shorter duration of disease, but not the treatment assignment, were positive independent predictors of the left ventricular ejection fraction at week 28. There was no significant difference in survival between the two groups (P = 0.96). The mortality rate for the entire group was 20 percent at 1 year and 56 percent at 4.3 years. Features suggesting an effective inflammatory response were associated with less severe initial disease. CONCLUSIONS: Our results do not support routine treatment of myocarditis with immunosuppressive drugs. Ventricular function improved regardless of whether patients received immunosuppressive therapy, but long-term mortality was high. Patients with a vigorous inflammatory response had less severe disease.

Frequency of hypoxanthine guanine phosphoribosyltransferase (HPRT-) T cells in the peripheral blood of cardiac transplant recipients. A noninvasive technique for the diagnosis of allograft rejection.

BACKGROUND: Histological evaluation of serial endomyocardial biopsies performed at fixed time intervals after cardiac transplantation is the universal method used for the detection of cardiac rejection and assessment of the adequacy of antirejection therapy. No noninvasive methodology thus far investigated has achieved a high enough sensitivity and predictive accuracy to be considered as a potential replacement for endomyocardial biopsy in the detection of rejection in adults. The present study exploited the finding that the rate of spontaneous mutation in the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene is higher in proliferating human T cells than in resting cells. Thus, it was reasoned that in the posttransplantation setting, the frequency of HPRT- cells in peripheral blood may provide an indirect measure of alloactivated T lymphocytes. METHODS AND RESULTS: This study consisted of determining the clonal frequency of HPRT- mutant cells (FMC/10(6) peripheral blood mononuclear cells [PBMCs]) within a total of 293 peripheral blood samples representing various numbers of sequential samples from each of 27 transplant recipients. These sequential samples represented time periods when endomyocardial biopsy specimens showed either (1) no evidence of rejection (n = 5 patients), (2) a single initial episode after transplantation of early (< 1 year) or late (> 1 year) rejection (n = 12 patients), or (3) multiple rejection episodes (n = 10 patients). Statistical analyses were used to quantify the time profiles of FMC/10(6) PBMCs in serial samples among transplant recipients and to determine the association of these profiles with both the onset of first rejection episodes and, in appropriate patients, the recurrence of rejection episodes. Data showed that PBMCs from patients with no evidence of rejection uniformly gave low values of < 6 FMC/10(6) cells, a frequency similar to that seen in healthy nontransplanted volunteers. In contrast, 19 of the 22 PBMC samples that were obtained from patients whose corresponding biopsy sample was diagnosed with a histological rejection grade of > or = 3 gave values of > 6 FMC/10(6) cells, 11 of which gave values > 50/10(6) cells (range, 146 to 46,982 FMC/10(6) cells). A significant association between the onset of first rejection and an increased rate of FMC/10(6) values was noted (P = .0001). The ability of a rising trend in FMC/10(6) values to correctly identify the onset of rejection was 81.8% and to correctly identify no rejection, 100%. In addition, a significant association between recurrent rejection episodes and persistence of high FMC/10(6) values in the weeks after treated rejection episodes was noted (P = .0003). The ability of a persistently elevated trend in values of FMC/10(6) cells to correctly identify recurrent rejection was 90% and to correctly identify no rejection, 100%. CONCLUSIONS: Increasing frequencies of HPRT- mutant cells in peripheral blood correlated with the onset of first rejection, and persistently elevated HPRT- mutant cells in the weeks after a treated rejection episode correlated with recurrent rejection. This quantitative noninvasive assay may thus serve as a useful adjunct to endomyocardial biopsy for monitoring post-cardiac transplantation patients, and its use as a prospective diagnostic tool merits further study.

Cytokine mRNA expression in postischemic/reperfused myocardium.

While the role of cytokines in mediating injury during hind limb skeletal muscle ischemia followed by reperfusion has recently been described, the role of cytokines in myocardial infarction and ischemia/reperfusion have remained relatively unexplored. We hypothesize that cytokines play an important role in the regulation of postischemic myocardial inflammation. This study reports the temporal sequence of proinflammatory cytokine gene expression in postischemic/reperfused myocardium and localizes interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha)-protein by immunostaining. Rats were subjected to either permanent left anterior descending (LAD) occlusion or to 35 minutes of LAD occlusion followed by reperfusion and sacrificed up to 7 days later. Rat-specific oligonucleotide probes were used to semiquantitatively assess the relative expression of mRNA for TNF-alpha, IL-1 beta, IL-2, IL-6, interferon-gamma (IFN-gamma), and transforming growth factor-beta 1 (TGF-beta 1) utilizing the reverse transcriptase-polymerase chain reaction amplification technique. Increased cardiac mRNA levels for all cytokines except IL-6 and IFN-gamma were measurable within 15 to 30 minutes of LAD occlusion and increased levels were generally sustained for 3 hours. During early reperfusion, mRNA levels for IL-6 and TGF-beta 1 were significantly reduced compared with permanent LAD occlusion. In both groups, cytokine mRNA levels all returned to baseline levels at 24 hours, while IL-1 beta, TNF-alpha, and TGF-beta 1 mRNA levels again rose significantly at 7 days only in animals with permanent LAD occlusion. Immunostaining for IL-1 beta and TNF-alpha protein revealed two patterns of reactivity: 1) microvascular staining for both IL-1 beta and TNF-alpha protein only in postischemic reperfused myocardium in early post-reperfusion time points; and 2) staining of infiltrating macrophages in healing infarct zones which was most prominent at 7 days after permanent LAD occlusion. These results provide evidence for local expression of cytokine mRNA in postischemic myocardium and suggest that regulation of local cytokine release is altered during the postischemic period.