Myocardial acoustics in pediatric allograft rejection

BACKGROUND: Ultrasonographic tissue characterization is the assessment of physical properties of biologic tissue on the basis of quantitative analysis of its acoustic characteristics. Abnormalities in microscopic structure that occur with cardiac allograft rejection may result in characteristic alterations in myocardial acoustics. Ultrasonographic tissue characterization may allow noninvasive detection of rejection. METHODS: Findings in 22 pediatric heart transplant patients undergoing routine surveillance for rejection by endomyocardial biopsy were prospectively evaluated. Off-line ultrasonographic tissue characterization analysis was done on transthoracic echocardiograms obtained at each biopsy. Within patients, tissue characterization texture measures derived from the ultrasonographic image data were compared with histologic findings. Univariate multiple regression analysis was used to identify texture measures associated with acute allograft rejection in a subgroup (n = 8) with at least one biopsy-proven episode of moderate rejection. RESULTS: Measures of homogeneity (co-occurrence matrix correlation and heterogeneity (run-length nonuniformity) decreased with moderate rejection (p < 0.03). Homogeneity measures decreased if the patient had a previous episode of rejection. Several measures of heterogeneity (gray level difference and run-length statistics) were affected by the presence of edema. Run-length nonuniformity was the only measure that differentiated moderate rejection from edema. Discriminant analysis on all 22 patients correctly identified 96% of first rejection episodes (sensitivity 80%, specificity 64%), 93% of moderate and severe rejection episodes (sensitivity 71%; specificity 62%), and 69% of all rejection episodes (sensitivity 51%, specificity 91%). CONCLUSIONS: Histologic changes associated with moderate and severe pediatric allograft rejection as reflected by characteristic alterations in myocardial acoustics can be assessed with ultrasonographic tissue characterization. Histologic changes associated with transplantation itself (resolution of rejection and edema) also affect myocardial acoustics and must be taken into account in rejection surveillance.     

Early cardiac allograft rejection is independent of regional myocardial blood flow

Noninvasive telemetric monitoring of canine heterotopic cardiac allograft unipolar peak-to-peak amplitude (UPPA) has permitted prospective surveillance for rejection; moreover, this technique is able to reliably detect rejection before the development of histologic evidence of myocyte necrosis. This study was performed to determine whether early cardiac allograft rejection and the accompanying decline in allograft UPPA were associated with alterations in regional myocardial blood flow (RMBF). Seven heterotopic, intrathoracic canine cardiac transplantations were performed using triple-drug immunosuppression. Native hearts and allografts were instrumented with right ventricular and left ventricular epicardial screw-in electrodes connected to subcutaneous telemeters. Daily measurement of native and graft UPPA was performed; using radioactive microspheres, native and graft RMBF were determined during the control period and when UPPA had declined by 15%, 30%, and 45%. Graft histologic status was determined by endomyocardial biopsy at the time of RMBF determination. Mean duration of the study was 19.7 +/- 3.9 days. Rejection was documented in all animals. The UPPA was stable in native hearts; UPPA declined in the allografts after the onset of rejection. A biphasic change in allograft blood flow was seen. Initially RMBF increased as UPPA declined; a 30% to 45% reduction in UPPA was associated with a 41% increase in RMBF (p = 0.028 versus allograft control). Subsequently, a significant decline in blood flow was observed for reductions in UPPA greater than 45% (0.68 +/- 0.44 versus 1.07 +/- 0.47 mL.g-1 x min-1 for a 30% to 45% decline in UPPA; p = 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of biopsy classification for rejection: relation to detection of myocardial damage by monoclonal antimyosin antibody imaging

OBJECTIVES: This study sought to compare the histologic grades of rejection in endomyocardial biopsy specimens with the global estimate of myocardial transplant-related cardiac damage detected by myocardial uptake of monoclonal antimyosin antibodies. BACKGROUND: The diagnosis and treatment of acute cardiac allograft rejection is based on the interpretation of endomyocardial biopsies. Because allograft rejection is a multifocal process and biopsy is obtained from a small area of the right ventricle, sampling error may occur. Global assessment of myocardial damage associated with graft rejection is now possible with the use of antimyosin scintigraphy. The present study was undertaken to compare the histologic grades of rejection in endomyocardial biopsy specimens with the global assessment of transplant-related myocardial damage detected by antimyosin scintigraphy. METHODS: Biopsies (n=395) from 112 patients were independently interpreted by three pathologists in a blinded manner according to the original Stanford four-grade (normal, mild, moderate and severe) and the current International Society of Heart and Lung Transplantation (ISHLT) seven-grade (0, 1A, 1B, 2, 3A, 3B and 4) classifications. The results were correlated with 395 antimyosin studies performed at the time of the biopsies. The heart/lung ratio of antimyosin antibody uptake was used to assess the severity of myocardial damage. RESULTS: In the Stanford biopsy grade classification, significantly higher antimyosin uptake, indicating increasing degrees of myocardial damage, were associated with normal (1.78+/-0.26), mild (1.88+/-0.31) and moderate (1.95+/-0.38) biopsy classifications for rejection (p < 0.01). In the ISHLT classification, significant differences were detected only for antimyosin uptake associated with grades 0 (1.77+/-0.26) and 3A (1.98+/-0.39) but not for intermediate scores (1A, 1B and 2). In view of the similar intensity of antibody uptake among the various grades, ISHLT biopsy scores were regrouped: normal biopsies in grade A; 1A and 1B as grade B; and 2 and 3A as grade C. Antimyosin uptake in grades A, B and C was 1.78+/-0.26, 1.88+/-0.31, 1.95+/-0.38, respectively (p < 0.01). CONCLUSIONS: The current ISHLT seven-grade scoring system does not reflect the progressive severity of myocardial damage associated with heart transplant rejection. Because myocardial damage constitutes the basis of treatment for allograft rejection, there is a need to reevaluate the ISHLT grading system, given its importance for multicenter trials.     

Sialic acid-depleted red cells following acute myocardial infarction

A reduction of red cell SA in patients following acute myocardial infarction is reported and the effects of SA-depleted red cells on cardiac index and alveolar capillary blood flow in the dog are described. The mean red cell SA in 26 patients following acute myocardial infarction was 0.021 +/- 0.001 compared with a mean of 0.031 +/- 0.002 mumol./0.1 ml RBC in 12 normal subjects (p less than 0.01). In five dogs injected with neuraminidase, an enzyme which removes SA from the red cell membrane, a 43% decrease in mean cardiac index from 2.3 +/- 0.22 to 1.3 +/- 0.16 (p less than 0.01) occurred. In films of the pulmonary microcircuation the mean widths of typical alveolar capillary beds decreased 42.6% +/- 5% (p less than 0.01). In three other dogs, autotransfusion with SA-depleted stored blood resulted in a 25% decrease in mean cardiac index from 2.0 +/- 0.21 to 1.5 +/- 0.21 (p less than 0.2), and a 21.7% +/- 0.9% (p less than 0.01) decrease in mean widths of typical alveolar capillary beds. We conclude that a reduction of red cell SA follows acute myocardial infarction and that SA-depleted red cells decrease cardiac index and alveolar capillary blood flow in the dogs.     

Relationship between myocardial collagen and echo amplitude in non-fibrotic hearts

The aim of the study was to investigate the relationship between myocardial collagen and regional echo amplitude in humans with non-fibrotic myocardium. The ratio of myocardial collagen to total myocardial protein was determined as the hydroxyproline/leucine ratio in endomyocardial biopsies obtained from the right ventricular side of the interventricular septum in orthotopically transplanted hearts. Regional echo amplitude was measured in the interventricular septum. Patients were studied prospectively. Twenty-five patients (five female, 20 male) who had undergone orthotopic cardiac transplantation were studied 355 to 2939 days (1009 +/- 718, mean +/- SD) post-transplantation at the time of annual cardiac catheterization and endomyocardial biopsy. Patient ages varied from 22 to 62 years (46 +/- 11). Donor ages were 14 to 47 years (25 +/- 8) and the ischaemic time, 90 to 245 min (151 +/- 42). Cardiac transplantation was performed for end-stage cardiac failure in all patients. The aetiology of cardiac failure was valvular heart disease in three, dilated cardiomyopathy in eight and ischaemic heart disease in the remainder. Echo amplitude studies were performed within 24 h of endomyocardial biopsy. All but one patient were on an immunosuppressive regime consisting of cyclosporine A and azathioprine with additional steroids in three. The remaining patient, who was the longest surviving patient in the study group, had never been treated with cyclosporine. This patient was maintained on steroids and azathioprine alone. No patient had clinical or histological evidence for acute cardiac rejection and all were clinically well. Five patients had angiographic evidence of coronary artery disease. All subject studies were performed at Harefield Hospital.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dipyridamole stress echocardiography and exercise testing for risk stratification after uncomplicated myocardial infarction

BACKGROUND: Risk stratification for subsequent cardiac events after an acute infarction can be obtained by exercise testing or dipyridamole stress echocardiography. It remains to be determined whether these modalities are equivalent and provide incremental information on top of clinical evaluation. The aim of our study was to compare the prognostic information obtained early after an acute uncomplicated myocardial infarction of high dose dipyridamole coupled with echocardiography (stress echo) or maximal symptom-limited exercise testing. METHODS AND RESULTS: Ninety patients underwent dipyridamole stress echo and exercise testing at a mean +/- SD of 9 +/- 4 days after admission for acute uncomplicated first myocardial infarction. All patients were prospectively followed for 22 +/- 16 months. There were 9 hard events (3 cardiac deaths and 6 acute myocardial infarctions) and 12 soft events due to post MI angina (6 angioplasty and 6 bypass surgery procedures). Univariate predictor of hard events was rest-stress wall motion score index variation (p = 0.009); univariate predictors of all events (hard + soft) were: positive exercise testing (p = 0.001), positive stress echo (p = 0.001), rest-stress wall motion score index variation (p = 0.002), extent of ischemia at echo (p = 0.008). Multivariate analysis by Cox selected a non-Q wave infarction and rest-stress wall motion score index variation as predictors of death or reinfarction (overall chi-square for the model 12.2, p = 0.0022). CONCLUSIONS: Stress echo is superior to ergometric variables for predicting events after uncomplicated myocardial infarction.     

Echocardiographic Doppler study of left ventricular filling in the diagnosis of minimal or moderate rejection in cardiac transplantation

The study of left ventricular filling by Doppler echocardiography may be a non-invasive diagnostic method of detection of acute rejection of cardiac transplants. The aim of this study was to assess the value of the method for diagnosis of minimal to moderate rejection (grades 1 to 3 of the Billingham classification). A total of 466 Doppler echocardiographic studies were performed in 23 cardiac transplantation patients (21 men, mean age 49.3 +/- 10 years) with endomyocardial biopsy as the reference method for the diagnosis of rejection. Over a follow-up period of 18.5 +/- 10 months, 22.7% of biopsies showed minimal or moderate rejection. The Doppler measurements of the isovolumic relaxation period and peak early diastolic (E) velocity with respect to the mitral velocity-time integral were no different in cases of acute rejection. The only difference observed was in the mitral half-pressure time which was much shorter in cases of rejection. However, after drawing a ROC graph, the accuracy of this parameter was insufficient for diagnosing rejection irrespective of the threshold of variation considered (23% sensitivity for a 20% shortening and 36% sensitivity for a 10% shortening). The authors conclude that Doppler echocardiographic study of left ventricular filling is of limited value for the diagnosis of acute minimal or moderate rejection in cardiac transplant patients. The half-pressure time may be a useful complement to endomyocardial biopsy or when biopsy investigations are performed less frequently.     

Medical options for early pregnancy termination

OBJECTIVES: We sought to assess the relation between glucose metabolism, myocardial perfusion and cardiac work after orthotopic heart transplantation. BACKGROUND: The metabolic profile of the transplanted cardiac muscle is affected by the lack of sympathetic innervation, impaired inotropic function, chronic vasculopathy, allograft rejection and immunosuppressive therapy. In relation to myocardial perfusion and cardiac work, glucose metabolism has not previously been studied in heart transplant recipients. METHODS: Regional myocardial blood flow (ml.min-1.g-1) and 18F-2-fluoro-2-deoxyglucose (18FDG) uptake rate (ml.s-1.g-1) were measured after an overnight fast in 9 healthy male volunteers (mean age +/- SD 32 +/- 7 years) and in 10 male patients (mean age 50 +/- 10 years) who had a nonrejecting heart transplant, normal left ventricular function and no angiographic evidence of epicardial coronary sclerosis. Measurements were made by using dynamic positron emission tomography (PET) with 15O-labeled water and 18FDG, respectively. Heart rate and blood pressure were also measured for calculation of rate-pressure product. RESULTS: 18FDG uptake was similar in all heart regions in the patients and volunteers (intrasubject regional variably 12 +/- 8% and 16 +/- 12%, respectively, p = 0.51). Regional myocardial blood flow was similarly evenly distributed (intrasubject regional variability 14 +/- 10% and 12 +/- 8%, respectively, p = 0.67). Mean 18FDG uptake and myocardial blood flow values for the whole heart are given because no regional differences were identified. 18FDG uptake was on average 196% higher in the patients than in the volunteers (2.90 +/- 1.79 x 10(-4) vs. 0.98 +/- 0.38 x 10(-4) ml.s-1.g-1, p = 0.006). Regional myocardial blood flow and rate-pressure product were similarly increased in the patient group, but by only 41% (1.14 +/- 0.3 vs. 0.81 +/- 0.13 ml.min-1.g-1, p = 0.008) and 53% (11,740 +/- 2,830 vs. 7,689 +/- 1,488, p = 0.001), respectively. CONCLUSIONS: 18FDG uptake is homogeneously increased in normally functioning nonrejecting heart transplants. This finding suggests that glucose may be a preferred substrate in the transplanted heart. The magnitude of this observed increase is significantly greater than that observed for myocardial blood flow or cardiac work. In the patient group, the latter two variables were increased to a similar degree over values in control hearts, indicating a coupling between cardiac work load and myocardial blood flow. The disproportionate rise in 18FDG uptake may be accounted for by inefficient metabolic utilization of glucose by the transplanted myocardium or by the influence of circulating catecholamines, which may stimulate glucose uptake independently of changes in cardiac work load.     

Measuring bioelectric myocardial impedance as a noninvasive method for diagnosis of graft rejection after heart transplantation

12 beagle dogs underwent neck-heart transplantation and were immunosuppressed with cyclosporine and methylprednisolone. Intramyocardial impedance was determined twice daily with four screw-in electrodes in the right and left ventricle. Transmyocardial biopsies and the intra-myocardial electrogram (IMEG) were performed as reference methods. 19 rejection episodes were induced. When acute rejection was seen in histology the animals were treated with pulsed 125 mg methylprednisolone over 5 consecutive days and immunosuppression was raised to sufficient levels. Successful treatment of rejection was controlled by biopsy. All hearts showed a uniform decrease of impedance of about 28.3% +/- 5.5% immediately after implantation, then reaching a stable plateau after 7 to 8 days. Impedance values then remained unchanged as long as rejection was absent. Biopsy findings of grade 1A to 1B (ISHLT) were accompanied by a statistically significant increase of impedance of 12.2% +/- 2.5%, of grade 2 to 3A of 19.2% +/- 3.2%, and of grade 3B to 4 of 27.0% +/- 2.9%. Sensitivity was 95%, specificity 91%. Successful treatment of rejection led to a uniform decrease of impedance to intramyocardial impedance for high frequencies can reliably indicate alterations of the cell membrane and the intracellular space during acute cardiac allograft rejection. The amount of increase of impedance is a reliable noninvasive parameter to graduate acute cardiac allograft rejection. The success of treatment of rejection can also be monitored by impedance. This noninvasive method is applicable for telemetric rejection monitoring via an implantable device, which would allow continuous rejection surveillance of a patient at home without hospital admission.     

Multiplane transesophageal echocardiographic doppler imaging accurately determines cardiac output measurements in critically ill patients

OBJECTIVES: To compare cardiac output and stroke volume measured by multiplane transesophageal Doppler echocardiography with that measured by the thermodilution technique. DESIGN: Prospective direct comparison of paired measurements by both techniques in each patient. SETTING: Cardiac surgery and myocardial infarction intensive care units. PATIENTS: Twenty-nine patients, mean age (+/- SD) 67 +/- 8 years. Nineteen had undergone open heart surgery and 10 had suffered acute myocardial infarction. METHODS: Cardiac output and stroke volume were measured simultaneously by the thermodilution technique and multiplane transesophageal Doppler echocardiography via the transgastric view (119 +/- 8 degrees) with the sample volume positioned at the level of the left ventricular outflow tract. RESULTS: Stroke volume and cardiac output measurements were obtained in 29 of 33 patients (88%). Mean values were 50 +/- 13 mL and 4.8 +/- 1.3 L/min by Doppler and 51 +/- 14 mL and 4.9 +/- 1.4 L/min by thermodilution (r = 0.90, r = 0.91, p < 0.001). The mean differences in values obtained with the two techniques were 1 +/- 6 mL (2 +/- 12%) and 0.1 +/- 0.7 L/min (2 +/- 12%). CONCLUSIONS: Multiplane transesophageal echocardiography enhances the ability to estimate accurately cardiac output and stroke volume by providing new access to left ventricular outflow tract in critically ill patients.     

Major histocompatibility complex class II antigen expression in rejecting cardiac allografts: detection using in vivo imaging with radiolabeled monoclonal antibody

BACKGROUND: Increased expression of major histocompatibility complex class II (MHC-II) antigen occurs during cardiac allograft rejection. We tested the hypotheses that (1) radiolabeled antibody to MHC-II antigen allows detection of cardiac allograft rejection using nuclear imaging techniques and (2) uptake of radiolabeled antibody to MHC-II antigen correlates with severity of rejection. METHODS AND RESULTS: Thirteen beagles with cervical cardiac allografts were studied for 64+/-23 days by use of myocardial biopsy and in vivo imaging. Uptake of radiolabeled (131I [n=2], 123I [n=1], or 111In [n=10]) antibody to MHC-II increased over baseline in 7 animals that developed histological evidence of progressively worsening allograft rejection (group A), from 72.2+/-46.1 to 176.8+/-102.0 counts/pixel/mCi (P<.009). In 4 beagles without progressively worsening allograft rejection (group B), uptake was unchanged during follow-up (74.4+/-43.8 and 60.2+/-37.4 counts/pixel/mCi; P=NS). In animals studied with 111In-labeled antibody, uptake increased from 102.9+/-23.1 at baseline to 233.2+/-82.7 counts/pixel/mCi at follow-up in group A animals (P=.036), with no significant change in group B (91.1+/-34.9 and 75.9+/-24.9 counts/pixel/mCi; P=NS). Uptake of 111In-labeled antibody was 107.5+/-35.7, 135.9+/-70.8, and 307.8+/-90.1 counts/pixel/mCi in biopsy samples showing evidence of mild, moderate, and severe rejection, respectively (P=.001). Biopsy samples showing mild, moderate, and intense MHC-II expression antibody uptake had uptakes of 92.6+/-36.3, 158.5+/-54.7, and 307.8+/-90.1 counts/pixel/mCi, respectively (P=.00004). CONCLUSIONS: Radiolabeled monoclonal antibodies to MHC-II antigen can detect cardiac allograft rejection in this large mammal model of cardiac allograft transplantation, and this technique may have a potential role in the detection of rejection in patients after cardiac transplantation.     

Effect of dietary lipids on hepatic and extrahepatic sterol 27-hydroxylase activity in high- and low-responding baboons

The aim of this study was to assess a Doppler-echocardiographic parameter which has not been previously reported for the diagnosis of acute cardiac rejection. The parameter was left ventricular isovolumic relaxation blood flow. Eighty patients who had undergone orthoptic cardiac transplantation were followed up regularly with echocardiography for a period of 2 years. In all, 495 echocardiographic studies were performed and the results compared with those of endomyocardial biopsy performed on the same day (11.4 echocardiographic studies per patient). In the absence of cardiac rejection, isovolumic relaxation Doppler signal was recorded in all patients (364/387 echo studies). This was a positive signal directed towards the apex detected by continuous mode Doppler in the apical position, arising along the interventricular septum in the mid part of the left ventricle (82% of cases) or from the basal region of the septum (18% of cases) and lasting throughout the phase of isovolumic relaxation. The maximal velocity was 0.53 +/- 0.08 m/s (range 0.32 to 0.73 m/s) : the velocity-time integral was 34 +/- 33 cm. This signal was associated with medioventricular endosystolic acceleration of blood flow in 75% of cases. The incidence of the isovolumic relaxation flow signal decreased in cardiac rejection with no significant changes in the other usual Doppler-echocardiographic parameters except for a significant decrease in the ejection fraction in the group with severe rejection. In the group with mild rejection (n = 89) an isovolumic relaxation flow signal was only observed in 52 cases (including 29 in whom immunosuppressive treatment was not increased). In patients with moderate rejection (n = 12) there were only 5 cases in which a isovolumic relaxation flow signal was recorded, and in the group with severe rejection (n = 7), the signal could only be recorded in 1 case. The authors conclude that the absence of an isovolumic relaxation blood flow signal in a cardiac transplant patient is a reliable sign of cardiac rejection with an excellent specificity (94%). The absence of this signal is a sensitive indicator of severe rejection (86%) but less so for moderate (58%) or mild rejection (42%).     

Effects of vesnarinone, a novel orally active inotropic agent with an immunosuppressive action, on experimental cardiac transplantation in rats

BACKGROUND: Vesnarinone (VES) has been used for treatment of patients with congestive heart failure. In addition to inotropic effects, it seems to have immunosuppressive action. We tested the hypothesis that VES suppresses graft rejection, inotropic dysfunction caused by early rejection, and chronic coronary obstruction in a heterotopic rat cardiac transplantation model. METHODS: (1) To study acute rejection, hearts from Lewis-Brown Norway (LBN) rats were transplanted into Lewis rats, which were treated with or without VES (50 or 100 mg/kg/day orally). (2) In a functional study, LBN hearts with or without VES (100 mg/kg/ day) were isolated and perfused on day 3 after transplantation to assess inotropic response to isoproterenol (3 x 10(-8) M). (3) To study chronic rejection, Lewis hearts were transplanted into Fisher 344 rats, which were treated with or without VES (50 mg/kg/day) for 90 days. Coronary obstructive disease was assessed by morphometric analysis. There were five to six animals in each group. RESULTS: (1) VES (100 mg/kg/day) prolonged LBN heart survival (11.7 +/- 0.7 vs. 9.6 +/- 0.7 days in control; P < 0.05). (2) Left ventricular developed pressure was depressed in transplanted hearts regardless of VES treatment (84 +/- 12, 90 +/- 8 vs. 144 +/- 16 mmHg in untransplanted hearts; P < 0.01). The developed pressure after administration of isoproterenol in VES-treated hearts (184 +/- 20 mmHg) was higher than transplanted hearts without VES (118 +/- 16 mmHg; P < 0.05), and similar to untransplanted hearts (203 +/- 27 mmHg; P = NS). (3) Transplanted hearts treated with or without VES showed similar grades of rejection (2.0 +/- 0.3 vs. 2.6 +/- 0.2; P = NS), intimal area (6,996 +/- 3,186 vs. 13,441 +/- 5,165 microns2; NS), and coronary luminal obstruction (45 +/- 16% vs. 67 +/- 14%; NS). CONCLUSIONS: VES produces mild prolongation in survival of rat heart grafts, but has no significant effect on chronic graft atherosclerosis. VES preserves the positive inotropic effects of isoproterenol that are otherwise deteriorated by early acute rejection.     

Treatment of humoral rejection after heart transplantation

BACKGROUND: Until a few years ago, the incidence of humoral rejection after heart transplantation was underestimated. These episodes were frequently very aggressive and often fatal, because the maintenance and emergency immunosuppression available at the time only inadequately covered the humoral branch of the immune response. In spite of individual case reports, the effects of blood purification procedures or cyclophosphamide in this situation can only be insufficiently estimated. METHODS: To evaluate this therapy concept, 20 dog-lymphocyte-antigen-matched dogs underwent heterotopic neck-heart transplantation. Fourteen dogs underwent transplantation after having been previously sensitized through multiple skin transplantations, 6 dogs were not sensitized (control). The animals received an induction with 3x 250 mg prednisolone, as well as triple immunosuppression (cyclosporine, azathioprine, and cortisone). Biopsy (light microscopy, immunofluorescence), intramyocardial voltage, electric myocardial impedance (>200 kHz, <10 kHz), and echocardiographic (left ventricular wall thickness, diastolic relaxation velocity) examinations were performed daily to monitor rejection. Rejection therapy was continued for 3 days according to the following regimen: apheresis, cortisone boluses (CB), and cyclophosphamide in group A1 (n = 4), apheresis and CB without cyclophosphamide in group A2 (n = 4), and CB only in group C (n = 6). The subsequent course under triple immunosuppression was then observed. RESULTS: In the sensitized animals the onset of severe humoral rejection on the fifth day deteriorated cardiac function down to 75% (70% to 80%) of the initial values. In groups A1 and A2, apheresis resulted in recovery to near-control values (89% to 94%) within two hours, and indeed to complete recovery (97% to 101%) after the second apheresis, that is, within 1 day. In group C recovery was delayed (2 days) and incomplete (84% to 91 %). After therapy was discontinued, rejection-related functional deterioration recurred immediately in group C, and from 2 to 3 days after apheresis, regardless of whether cyclophosphamide therapy was performed (group A1) or not (group A2). In the control group all animals showed a rejection-free posttransplantation course. CONCLUSIONS: By diluting inflammatory mediators, apheresis leads to a rapid improvement in cardiac function during severe humoral rejection after head transplantation. Neither apheresis nor cyclophosphamide therapy are able to have an immediate positive influence on the activation of the immune cascade and to prevent an ongoing rejection.     

Beta-adrenergic signal transduction following carvedilol treatment in hypertensive cardiac hypertrophy

Cytokines and cytotoxic agents, including nitric oxide (NO) released by macrophages, play important roles during cardiac allograft rejection. In contrast to agents that suppress T-lymphocyte function, CNI-1493 is a multivalent guanylhydrazone compound that inhibits the synthesis and release of proinflammatory cytokines and NO from macrophages. This study investigated the effects of CNI-1493 on rejecting rat cardiac allografts by using Lewis to Wistar-Furth heterotopic cardiac transplants. CNI-1493 (2 mg/kg i.p., b.i.d.) or vehicle (water) was administered beginning the day before surgery. Rat cardiac allograft survival to cessation of heart beat, apoptosis of cardiac myocytes, degree of myocardial inflammation, and inducible nitric oxide synthase (iNOS) messenger RNA (mRNA), protein, and enzyme activity were studied at days 1, 3, 5, and 7 after transplantation. Allograft survival was increased significantly by 26% from 7.5 +/- 0.8 days in vehicle-treated rats (n = 6) to 9.5 +/- 1.2 days in CNI-1493-treated rats (n = 8, p < 0.05). Apoptotic cells per mm2 myocardium decreased from 2.25 +/- 1.25 to 0.84 +/- 0.49 at day 3 and 31.2 +/- 2.9 to 17.6 +/- 5.43 at day 5 after transplantation with CNI-1493 treatment (p < 0.05). The number of apoptotic myocytes and loss of cardiac muscle cells also decreased significantly at day 5 in the treated animals (p < 0.05). The reduction of myocyte loss at day 5 coincided with a significant decrease of the inflammatory response and reduced macrophage influx (p < 0.05). Myocardial iNOS mRNA, protein, and enzyme levels increased during the course of allograft rejection, and CNI-1493 did not significantly reduce iNOS expression in the rejecting rat allograft. CNI-1493 prolongs allograft survival and reduces myocyte loss, apoptosis, and inflammation during rat cardiac allograft rejection. These effects of CNI-1493 appear to be unrelated to altered NO synthesis but may be related to effects of the drug to inhibit macrophage synthesis of cytokines.     

Myocsrdial uptake of technetium-99m stannous pyrophosphate following direct current transthoracic countershock

The effect of direct current (DC) countershock upon myocardial technetium-99m stannous pyrophosphate (PYP) uptake was studied in 22 dogs. All eight dogs imaged had positive abnormal PYP scintigrams that were usually indistinguishable from experimental infarction. In three animals, additional areas of radionuclide uptake were seen in overlying noncardiac tissue. Left and right ventricular myocardial PYP uptake averaged (+/- SEM) 23 +/- 5 times control and 24 +/- 6 times control, respectively. These activity ratios occurred without reduction in regional myocardial blood flow (RMBF), and were associated with histologic evidence of necrosis. The necrosis was usually epicardial, corresponding to the transmural site of greatest PYP uptake. The magnitude of PYP accumulation and the weight of damaged tissue increased with increasing applied energy. Thus, PYP uptake following DC countershock could result in false-positive interpretation of acute ischemic myocardial infarction. Since RMBF is normal in regions of PYP uptake, the major determinant of radionuclide accumulation is the extent of cellular damage.     

The dipsogen angiotensin II does not stimulate ethanol intake in mice

The Banff classification of acute rejection is based on histologic grades and scores for borderline changes, glomerular, vascular, interstitial and tubular lesions. We reviewed 56 episodes of acute rejection occurring in 44 kidney allograft recipients (30 cadaveric and 14 living donor transplants), comparing Banff classification to degree of reversibility of rejection. Rejection reversal was defined as complete if serum creatinine returned < or = 25% of baseline, partial if creatinine was > 25% to < 75% of baseline, and irreversible if creatinine was > or = 75% of baseline or graft loss occurred. Eight biopsies were classified as borderline (SUM score 1.6 +/- 0.5), 14 grade I (SUM score 3.3 +/- 0.4), 19 grade II (SUM score 4.2 +/- 0.3), and 15 grade III (SUM score 8.5 +/- 0.4). SUM distinguished borderline and grade III rejections, but not grades I and II. Clinically, grade and SUM score correlated with rejection reversal. Complete reversal of rejection occurred in 93% of patients with grade I rejection, while 47% of patients with grade III had irreversible rejection. The mean SUM for complete reversal was 3.9 +/- 0.34 and was different from SUM of partial (6.0 +/- 0.86) and irreversible (8.5 +/- 0.93), P < 0.006. Meanwhile, vascular scores were similar for rejections with complete (0.9 +/- 0.2) or partial (1.0 +/- 0.4) reversal, but significantly higher in those with irreversible rejection (3.0 +/- 0.4, P < 0.000). Likewise, mean scores for tubulitis and interstitial inflammation were significantly higher for irreversible rejection. Resolution of rejection by steroids was correlated to low vascular score (steroid sensitive 0.65 +/- 0.25 vs. steroid resistant 1.42 +/- 0.18, P < 0.01), and low SUM score (steroid sensitive 3.7 +/- 0.5 vs. steroid resistant 5.22 +/- 0.43, P < 0.04). Neither scores for tubulitis nor interstitial cellular inflammation were predictive of steroid sensitivity. These data demonstrate that Banff scoring has clinical relevance in predicting rejection reversal and has implications to first-line therapy of rejection episodes.     

The sensitivity of transbronchial biopsy for the diagnosis of acute lung rejection

Transbronchial biopsy has become the procedure of choice for the diagnosis of acute lung rejection after transplantation, but the sensitivity of the technique in this setting remains unknown. In this study, 14 mongrel dogs underwent left lung transplantation, after which triple-drug immunosuppression was given for 5 days and then all immunosuppression was stopped. All animals had clear chest radiographs at this time. Transbronchial biopsy was performed in nine lung regions (two to six pieces of lung tissue were obtained per region, with a mean of 4.3 pieces per region) before the animals were killed 2 to 4 days later, at which time varying degrees of rejection had occurred. Rejection was graded histologically on a scale of 0 to 3 (0 = no rejection, 1 = mild rejection, 2 = moderate rejection, 3 = severe rejection) in each piece of lung tissue obtained at transbronchial biopsy. After the dogs were put to death, the true state of lung rejection was determined by histologic examination of the entire lung. We calculated the sensitivity of transbronchial biopsy with 95% confidence intervals. Five pieces of lung tissue were needed to yield a sensitivity of 92% (82%, 100%) to identify mild rejection in the entire lung with transbronchial biopsy. Three pieces of lung tissue were needed to yield a sensitivity of 92% (84%, 100%) to identify the presence of moderate to severe rejection in the entire lung (that is, rejection that requires pulse therapy) on transbronchial biopsy. These results indicate that three to five pieces of lung tissue that are suitable for diagnostic purposes obtained at transbronchial biopsy are adequate for the diagnosis of acute pulmonary rejection after lung transplantation.     

Photopheresis for the prevention of rejection in cardiac transplantation. Photopheresis Transplantation Study Group

BACKGROUND: Photopheresis is an immunoregulatory technique in which lymphocytes are reinfused after exposure to a photoactive compound (methoxsalen) and ultraviolet A light. We performed a preliminary study to assess the safety and efficacy of photopheresis in the prevention of acute rejection of cardiac allografts. METHODS: A total of 60 consecutive eligible recipients of primary cardiac transplants were randomly assigned to standard triple-drug immunosuppressive therapy (cyclosporine, azathioprine, and prednisone) alone or in conjunction with photopheresis. The photopheresis group received a total of 24 photopheresis treatments, each pair of treatments given on two consecutive days, during the first six months after transplantation. The regimen for maintenance immunosuppression, the definition and treatment of rejection episodes, the use of prophylactic antibiotics, and the schedule for cardiac biopsies were standardized among all 12 study centers. All the cardiac-biopsy samples were graded in a blinded manner at a central pathology laboratory. Plasma from the subgroup of 34 patients (57 percent) who were enrolled at the nine U.S. centers was analyzed by polymerase-chain-reaction amplification for cytomegalovirus DNA. RESULTS: After six months of follow-up, the mean (+/-SD) number of episodes of acute rejection per patient was 1.44+/-1.0 in the standard-therapy group, as compared with 0.91+/-1.0 in the photopheresis group (P=0.04). Significantly more patients in the photopheresis group had one rejection episode or none (27 of 33) than in the standard-therapy group (14 of 27), and significantly fewer patients in the photopheresis group had two or more rejection episodes (6 of 33) than in the standard-therapy group (13 of 27, P=0.02). There was no significant difference in the time to a first episode of rejection, the incidence of rejection associated with hemodynamic compromise, or survival at 6 and 12 months. Although there were no significant differences in the rates or types of infection, cytomegalovirus DNA was detected significantly less frequently in the photopheresis group than in the standard-therapy group (P=0.04). CONCLUSIONS: In this pilot study, the addition of photopheresis to triple-drug immunosuppressive therapy significantly decreased the risk of cardiac rejection without increasing the incidence of infection.     

Life-supporting pig-to-baboon heart xenotransplantation

BACKGROUND: The aim of this study was to investigate the effect of the expression of human decay-accelerating factor in transgenic pigs on hyperacute rejection in a pig-to-baboon heterotopic heart transplantation model and to assess the ability of such transgenic pig hearts in supporting the life of a primate when transplanted orthotopically. METHODS: Hearts from pigs transgenic for human decay-accelerating factor were transplanted heterotopically (n = 3) and orthotopically (n = 5) into the baboon. All animals received cyclosporine, steroids, and cyclophosphamide. Blood was sampled regularly for total antipig antibody titers, trough cyclosporine levels, full blood count, electrolytes, and creatinine. Rejection of the heterotopic hearts was defined as the absence of palpable cardiac pulsation. Explanted hearts were examined histologically with hematoxylin and eosin and with immunochemistry for complement components C3, C4, C9, and immunoglobulin M. RESULTS: None of the hearts were hyperacutely rejected. In the heterotopic group one heart underwent acute vascular rejection on day 13, and the remaining two recipients with beating xenografts were killed on days 2 and 21. In the orthotopic group, one recipient with a life-supporting xenograft was killed on day 9 because of poor general condition. Histologic examination demonstrated no evidence of rejection. Two xenografts stopped beating on day 5, and histologic study showed acute vascular rejection in both. There were also two graft failures for technical reasons in this group. CONCLUSIONS: Hyperacute rejection is abrogated in pig-to-baboon heart xenotransplantation with the expression of the human decay-accelerating factor transgene. The human decay-accelerating factor transgenic pig heart is able to support primate life for a prolonged period.