Noninvasive diagnosis of cardiac allograft rejection. Another of many searches for the grail

Evaluation of CXCL9 and CXCL10 as circulating biomarkers of human cardiac allograft rejection

Background

Cardiac allograft rejection remains a significant clinical problem in the early phase after heart transplantation and requires frequent surveillance with endomyocardial biopsy. However, this is an invasive procedure, which is unpleasant for the patient and carries a certain risk. Therefore, a sensitive non-invasive biomarker of acute rejection would be desirable.

Methods

Endomyocardial tissue samples and serum were obtained in connection with clinical biopsies from twenty consecutive heart transplant patients followed for six months. A rejection episode was observed in 14 patients (11 men and 3 women) and biopsies obtained before, during and after the episode were identified. Endomyocardial RNA, from three patients, matching these three points in time were analysed with DNA microarray. Genes showing up-regulation during rejection followed by normalization after the rejection episode were evaluated further with real-time RT-PCR. Finally, ELISA was performed to investigate whether change in gene-regulation during graft rejection was reflected in altered concentrations of the encoded protein in serum.

Results

Three potential cardiac allograft rejection biomarker genes, chemokine (C-X-C motif) ligand 9 (CXCL9), chemokine (C-X-C motif) ligand 10 (CXCL10) and Natriuretic peptide precursor A (NPPA), from the DNA microarray analysis were selected for further evaluation. CXCL9 was significantly upregulated during rejection (p < 0.05) and CXCL10 displayed a similar pattern without reaching statistical significance. Serum levels of CXCL9 and CXCL10 were measured by ELISA in samples from 10 patients before, during and after cardiac rejection. There were no changes in CXCL9 and CXCL10 serum concentrations during cardiac rejection. Both chemokines displayed large individual variations in the selected samples, but the serum levels between the two chemokines correlated (p < 0.001).

Conclusion

We conclude, that despite a distinct up-regulation of CXCL9 mRNA in human hearts during cardiac allograft rejection, this was not reflected in the serum levels of the encoded protein. Thus, in contrast to previous suggestions, serum CXCL9 does not appear to be a promising serum biomarker for cardiac allograft rejection.

Value of plasma B-type natriuretic peptide as a marker for rejection in pediatric heart transplant recipients

We analyzed 211 consecutive plasma B-type natriuretic peptide (BNP) measurements in 59 pediatric heart transplant patients along with echocardiographic and right ventricular endomyocardial biopsy samples. Patients with a biopsy specimen negative for rejection had significantly lower BNP levels than those patients with a biopsy positive (p </=0.04) for rejection. BNP significantly decreased with treatment (p </=0.007). BNP levels in the first year after heart transplantation in all patients were significantly greater than BNP levels after the first year in all patients (p <0.001).

Non-invasive in vivo imaging of myocardial apoptosis and necrosis

Myocardial necrosis plays an important role in the pathogenesis of various cardiovascular disorders and can result from different myocardial insults. Its non-invasive identification and localisation therefore may help in the diagnosis of these disorders, as well as in prognosis and assessment of treatment response. Apoptosis, or programmed cell death, is important in the spectrum of myocardial damage since it is gradually becoming more apparent that cell death may begin as apoptosis and not as necrosis. First attempts to directly visualise the area of myocardial necrosis were based on recognition of myocardial infarction with "hot spot imaging agents" in patients with chest pain. Since then, the study of myocardial necrosis with gamma imaging agents has gone beyond the detection of myocardial infarction, and attempts have been made to diagnose other cardiovascular disorders associated with cardiac cell death such as heart transplant rejection, myocarditis, cardiotoxicity and cardiomyopathies. Traditionally, two hot spot imaging agents have been used for the detection of myocardial necrosis, (99m)Tc-pyrophosphate and (111)In-antimyosin. In addition, preliminary studies have demonstrated promising results with (99m)Tc-glucarate. Recently, (99m)Tc-annexin V has been successfully used for non-invasive gamma imaging of apoptosis after acute myocardial infarction, acute myocardial ischaemia, acute cardiac allograft rejection and malignant intracardiac tumours. This review article focusses on the characteristics of these different myocardial necrotic and apoptotic markers and compares their role in the assessment of myocardial damage.

Apoptosis in cardiac transplant rejection

Apoptosis occurs in human cardiac allograft rejection and may occur with all degrees of rejection and even in its absence. The prevalence and severity of apoptosis is determined predominantly by the intensity of macrophage infiltration and may be mediated by NO-related mechanisms. Apoptosis of interstitial, endothelial, and inflammatory cells is also present in heart allografts and may influence the degree and extent of vascular injury contributing to allograft rejection. Ongoing apoptosis of inflammatory cells suggests an immunoregulatory role. Studies of the involvement of NO in myocyte damage and Fas-FasL interactions in peripheral tolerance have raised the exciting possibility that these pathways can be exploited in a beneficial way. Further understanding of the role of apoptosis and the cellular and biochemical mechanisms that are involved in cardiac myocyte death and in inflammatory, endothelial, and interstitial cell death may provide insights into therapeutic modalities to suppress allograft rejection and vasculopathy.

Early detection of acute allograft rejection by linear and nonlinear analysis of heart rate variability

OBJECTIVE

The first months after orthotopic heart transplantation are associated with the highest risk of acute allograft rejection. This study explores the utility and reliability of linear and novel nonlinear metrics of heart rate variability as predictors of graft rejection. The underlying hypothesis is that the transplanted heart, in response to inflammatory mediators, alters the dynamic properties of its rhythm-generating system.

METHODS

In a cross-sectional study of 45 patients who had undergone heart transplantation, spanning a period of 4 months after the operation, heart rate variability was examined by time- and frequency-domain analysis. The nonlinear features of heart rate variability were studied by computing a pointwise correlation dimension of R-R interval time series. The results of heart rate variability analysis were compared with those of endomyocardial surveillance biopsy studies using the International Society for Heart and Lung Transplantation scoring system.

RESULTS

Duration of heart transplantation itself exhibited a significant (P<.05) association with the onset of rejection. Specific predictors of acute rejection based on heart rate variability were identified, including shortening of the R-R interval (from 700 +/- 68 to 648 +/- 72 ms), an increase in the ratio of low-frequency (0.04-0.15 Hz) to high-frequency (0.15-0.40 Hz) spectral power (from 0.3 +/- 0.2 to 0.6 +/- 0.4), and a decrease in pointwise correlation dimension values (from 1.7 +/- 0.7 to 0.9 +/- 0.3 units). Multivariable logistic regression analysis (R (2) = 0.4) revealed that the only significant independent risk predictors were pointwise correlation dimension (odds ratio, 2.2 per 0.1 unit) and duration of heart transplantation (odds ratio, 1.7 per week).

CONCLUSION

Nonlinear measures of heart rate variability provide noninvasive means for identifying patients undergoing cardiac transplantation with acute rejection, thereby enabling the assessment of the time-dependent adaptive response of the donor heart to its host.

Non-invasive cardiac allograft monitoring: the graz experience

Based on previous reports by our group, initial studies on non-invasive cardiac graft monitoring have been presented recently. In this study we define new parameters to monitor rejection and infection after heart transplantation (HTX) the ventricular evoked response (VER) T-slew rate parameter is defined as the maximum negative slope in the descending part of the repolarization phase of the VER. We calculated the VER duration parameter in milliseconds and defined it as the time between the pacemaker spike and the cross-over of the baseline, with the slope line used to calculate the VER T-slew rate. During the HTX procedure, we implant wide-band telemetric pacemakers and fractally coated, epimyocardial electrodes (Physios CTM 01 and ELC 54-UP, Biotronik; Berlin, Germany). During each follow-up and on biopsy days, intramyocardial electrogram sequences were obtained and sent via the Internet to the central data-processing unit in Graz. We scored the infection status of the patients before data acquisition. The VER parameters were automatically calculated and send back within a few minutes. We prospectivly compared 1,613 follow-ups from 42 patients with biopsy (International Society of Heart and Lung Transplantation grading) and infection classification. The VER duration parameter did not change during rejection; however, we found an increase during clinically apparent infection. The VER T-slew rate parameter was lower during rejection grade 2 or higher, as well as during clinically apparent infection. The negative predictive value to rule out rejection was 99%. Our results indicate that rejection and infection cause different, reproducible effects on the electrical activity of the transplanted heart. Non-invasive cardiac graft monitoring may reduce the need for surveillance biopsies and may offer a tool to optimize immunosuppressive therapy after HTX.

Indium-111 monoclonal antimyosin cardiac scintigraphy in men with idiopathic dilated cardiomyopathy

This study examined the prognostic value and the evolution of the heart-to-lung ratio of monoclonal antimyosin antibody (MAA) uptake in patients with a diagnosis of idiopathic dilated cardiomyopathy (IDC). Uptake of indium-111-labeled MAA occurs when the myocytes become irreversibly damaged. The study included 29 men with IDC followed up for 3 years. The diagnosis was verified by endomyocardial biopsy in all patients. Patients who survived beyond 1 year were restudied. Baseline heart-to-lung ratio of MAA was 1.74+/-0.22. Multivariate Cox regression analysis revealed that MAA and New York Heart Association class were independent predictors of late mortality, with a hazard ratio of 4.4 (95% confidence interval 1.1 to 17.9, p = 0.036) and 7.5 (95% confidence interval 2.0 to 28.4, p = 0.003), respectively, when heart-to-lung ratio of MAA uptake was > 1.74 and New York Heart Association class was >11. When these patients were divided into those with chronic IDC (group I [n = 19]) and those with subacute IDC (group II [n = 10]), baseline heart-to-lung ratio was 1.7+/-0.2 and 1.86+/-0.25, respectively (p = NS). In the surviving patients, on restudy, the heart-to-lung ratio of MAA uptake was unchanged in group I (1.64+/-0.20, p = NS), but had decreased to the level of group I (1.66+/-0.21 [p = 0.008]) in group II. Thus, men with IDC and a high heart-to-lung ratio of MAA uptake have a worse long-term prognosis than patients with a lower ratio. The heart-to-lung ratio of MAA decreases comparably over time in subacute IDC and remains stable in chronic IDC.

Myocardial high-energy phosphate metabolism in heart transplant patients is temporarily altered irrespective of rejection

A reliable, sensitive, non-invasive alternative for transvenous endomyocardial biopsy in detecting cardiac allograft rejection is desirable for optimal management of heart transplant patients. To establish whether (31)P magnetic resonance spectroscopy can become a non-invasive tool for detecting cardiac allograft rejection, the cardiac high-energy phosphate metabolism of human heart transplants was serially examined in 13 patients by means of (31)P MRS from post-operative day 13 to day 294, and compared with histologic evaluation of endomyocardial biopsies. Biopsy scores of 2 or higher, according to the Working Formulation criteria of Billingham et al., were considered to indicate rejection. Logistic regression, which was corrected for differences between the individual patients and the time after transplantation, showed no significant correlation between the occurrence of histologically detected rejection and the PCr:ATP ratio. However, using an analysis of variance, the PCr:ATP ratios of non-rejecting cases obtained within 50 days after transplantation (mean: 27 +/- 11 days) appeared to be significantly different from those obtained after post-operative day 50 [0.95 +/- 0.17 (n = 25) vs 1.17 +/- 0.17 (n = 32), mean +/- SD; p < 0.01]. No significant difference was observed between the PCr:ATP ratios obtained 100 days after transplantation (mean: 162 +/- 52 days) and the PCr:ATP ratios in the hearts of healthy volunteers [1.18 +/- 0. 18 (n = 19) and 1.23 +/- 0.17 (n = 6), mean +/- SD, respectively; p = 0.55]. The PCr:ATP ratio in transplanted human hearts is not a sensitive indicator for the detection of early acute human cardiac allograft rejection. This may be due to a temporarily altered high-energy phosphate metabolism early after transplantation irrespective of rejection.

Detection of acute cardiac rejection by analysis of heart rate variability in heterotopically transplanted rats

BACKGROUND

A less-invasive method for cardiac allograft surveillance than endocardial biopsy is needed. We analyzed heart rate variability of heterotopically transplanted rat hearts as a method of detecting rejection of rat cardiac allografts.

METHODS

Two kinds of heterotopic transplants were performed: 1) Brown-Norway rats received Brown-Norway rat isografts, and 2) Lewis rats received Brown-Norway rat allografts. The electrocardiogram (ECG) of the grafts were serially recorded under non-anesthetized and non-restricted conditions using a telemetric ECG transmitter implanted in the recipient's abdomen. Frequency domain analysis of the ECGs was performed using a fast Fourier algorithm.

RESULTS

Total power of the heart rate variability in the isograft heart was reduced to 1.1%, compared to normal subjects without transplantation (p < .001). In the allograft heart, it was also reduced to 1.0% on days 1.5 (rejection score 0 to 1), but gradually increased thereafter up to 185% on day 6 (rejection score 3.75+/-0.50). The increase in spectral power was frequency-dependent (i.e., changes in the power in lower frequency range [LF, 0.04 to 0.67 Hz] were significantly higher than other ranges). This increase was reversible when immunosuppressive therapy was performed with the use of cyclosporine A. In the allograft group, peak-to-peak amplitudes of the QRS complex and heart rate were significantly decreased on day 5.5 or later, whereas the power of the LF was significantly increased by day 3.5 or later.

CONCLUSIONS

Our data suggest that heart rate variability analysis is a promising noninvasive marker for early detection of cardiac allograft rejection. This method may also provide a sensitive means of assessing the effects of immunosuppressive therapy.

Noninvasive detection of cardiac transplant rejection using electronic monitoring

Cardiac transplantation has become the therapy of choice for the treatment of end-stage congestive heart failure. One of the major problems after cardiac transplantation is acute cellular rejection. The diagnosis of rejection is crucial to the management of transplant patients because rejection must be successfully diagnosed and reversed. Endomyocardial biopsy is the major method for detecting cardiac transplant rejection; however, this approach is invasive and is associated with morbidity and mortality. One noninvasive approach for detecting rejection is to monitor changes in the intramyocardial electrograms using pacemakers. Changes in the ventricular evoked response amplitude (VERA) obtained during ventricular pacing have been correlated with the presence of acute cellular rejection in both single center studies in Europe and a multicenter trial in five transplant centers in the United States. Given the high negative predictive value for the VERA, this approach may provide a screen to determine if individual patients require more invasive procedures such as endomyocardial biopsy and may aid in reducing the number of biopsies needed.

Noninvasive rejection monitoring of cardiac transplants using high resolution intramyocardial electrograms: initial US multicenter experience

Endomyocardial biopsy (EMB) remains the mainstay for the diagnosis of acute cellular rejection in cardiac transplant patients. A noninvasive alternative that would supplant or reduce the number of EMBs would be a highly desirable and cost-effective tool. To evaluate one potential alternative, a pacemaker with high resolution telemetry capabilities and two fractally coated epimyocardial leads were implanted in 30 patients at five transplant centers during the heart transplant procedure. Ventricular electrograms were recorded during intrinsic and paced activity and digitized to a laptop-based data acquisition device. Electrograms were recorded at frequent intervals and systematically on days when EMBs were performed. The electrogram data were then transferred via the Internet to a central data processing site. Clinical patient management was blinded to the electrogram results and varied considerably among the five centers. Using EMB together with clinical assessment of the transplant revealed 18 cases of clinically significant rejection beyond postoperative day 27 that required antirejection therapy. The normalized parameter values extracted from the electrogram recordings during pacing (the ventricular evoked response) that were associated with significant rejection were statistically lower (86% +/- 16% versus 96% +/- 22%, P < 0.005). The application of a single-threshold diagnosis model to the parameter values allowed detection of significant rejection with a negative predictive value of 98%. This analysis also showed that as many as 55% of the routine surveillance EMBs could have been eliminated had the pacemaker monitoring technique been used as a screening tool prior to EMB. A prospective study should further define the role of this technique in the detection and management of cardiac transplant patients.

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.

Spectrum of alcohol-induced myocardial damage detected by indium-111-labeled monoclonal antimyosin antibodies

OBJECTIVES

We sought to determine the prevalence, intensity and evolving changes of myocardial damage detected by myocardial uptake of antimyosin antibodies in patients with alcohol-induced dilated cardiomyopathy, alcohol addicts attending a detoxification unit and healthy subjects with short-term alcohol consumption.

BACKGROUND

Evidence of alcohol-induced myocardial damage may be provided by myocardial uptake of indium-111-labeled monoclonal antimyosin antibodies. The spectrum of such damage in patients who are heavy drinkers (> 100 g for > 10 years), with or without cardiomyopathy, and the impact of short-term alcohol ingestion on antimyosin antibody uptake have not been adequately explored.

METHODS

One hundred twenty antimyosin studies were performed in 56 patients with dilated cardiomyopathy (group I), 15 alcohol addicts attending a detoxification unit (group II) and 6 volunteers for short-term alcohol ingestion (group III). Estimation of antibody uptake was calculated through a heart/lung ratio (HLR) (normal < 1.55).

RESULTS

The 56 patients in group I (54 men, 2 women; mean [+/-SD] age 46 +/- 11 years) had consumed 123 +/- 60 g/day of alcohol for 21 +/- 9 years, for a cumulative intake of 914 +/- 478 kg. Mean duration of symptoms was 46 +/- 49 months. Mean left ventricular end-diastolic diameter was 71 +/- 10 mm, and mean ejection fraction was 28 +/- 12%. No differences in New York Heart Association functional class, ventricular size or ejection fraction were noted between 28 active and 28 past consumers, except for the prevalence and intensity of antibody uptake (75% vs. 32%, p < 0.001) and HLR (1.75 +/- 0.26 vs. 1.49 +/- 0.17, p = 0.0001). In 19 patients in the active group restudied after alcohol withdrawal, antibody uptake decreased (from 1.76 +/- 0.17 to 1.55 +/- 0.19, p < 0.001), and ejection fraction improved (from 30 +/- 12% to 43 +/- 16%, (p < 0.001). No changes occurred in the 15 past consumers restudied. The 15 male patients in group II (mean age 36 +/- 4 years) had consumed 156 +/- 59 g/day for 17 +/- 5 years, for a cumulative alcohol intake of 978 +/- 537 kg, an amount similar to that in patients in group I, but antimyosin antibody uptake was detected in only 3 (20%) of 15 patients. None of six group III subjects developed antibody uptake after short-term ethanol ingestion. Despite the small sample size, the power to detect clinically relevant differences in most variables that did not reach statistical significance was amply sufficient.

CONCLUSIONS

In alcohol-induced dilated cardiomyopathy, alcohol withdrawal is associated with the reduction or disappearance of myocardial damage and improvement of function. The difference in prevalence of antimyosin antibody uptake in patients with and without cardiac disease who consume similar amounts of alcohol suggests the presence of those with different myocardial susceptibilities to alcohol. Short-term ethanol ingestion in healthy subjects does not induce detectable uptake of antimyosin antibodies.

Noninvasive diagnosis of cardiac allograft rejection in an orthotopic canine model

BACKGROUND

A decline in the R wave voltage obtained from surface electrocardiograms once correlated with cardiac allograft rejection. With cyclosporine therapy, however, these electrocardiographic findings became inconsistent, occurring only during severe rejection episodes. Despite cyclosporine use, intramyocardial unipolar peak-to-peak amplitudes obtained from plunge electrodes are reported to be highly sensitive and specific for diagnosing rejection. These reports are based on heterotopic grafts, which atrophy over time, making long-term voltage changes during rejection difficult to interpret. The purpose of this study was to use analysis of unipolar peak-to-peak amplitudes as a prospective monitoring tool for diagnosing orthotopic cardiac allograft rejection.

METHODS

Ten adult mongrel dogs underwent orthotopic heart transplantation with the attachment of four intramyocardial leads. The unipolar peak-to-peak amplitudes were measured daily and compared with endomyocardial biopsy results.

RESULTS

We found that intramyocardial unipolar peak-to-peak amplitude analysis had a sensitivity and a specificity of 100% for diagnosing rejection. We also found that as the number of myocardial leads increased, the sensitivity of detecting rejection also increased.

CONCLUSIONS

We conclude that unipolar peak-to-peak amplitude analysis is an accurate noninvasive means for early detection of cardiac allograft rejection in an orthotopic model. Its success should allow less frequent, more selective use of endomyocardial biopsy.

Heterotopic heart transplantation alters high-energy phosphate metabolism irrespective of cardiac allograft rejection

This study was undertaken to validate the potential of 31P magnetic resonance spectroscopy (MRS) as a noninvasive alternative for transvenous endomyocardial biopsy in detecting cardiac allograft rejection. Donor hearts from either Lewis rats (L) or Brown-Norway rats (BN) were transplanted into the neck of L rats resulting in a non-rejecting group L-L and a rejecting group L-BN. L-L and L-BN rats were serially studied by means of 31P MRS from postoperatine day 1-8. In addition, rejection was confirmed by histology. A similar, marked decrease in phosphocreative/beta- adenosinetriphosphate (PCr/ATP) ratio from day 1-3 was observed in both L-L and L-BN hearts. This ratio levelled off on postoperative day 3 and remained depressed on subsequent postoperative days in both groups, although histology showed an increase in the severity of rejection in L-BN. However, the PCr signal/noise ratio in L-BN started to decrease after day 4, coinciding with the histologic evidence of severe rejection (score IV), whereas in L-L hearts (score 0) this ratio remained unaltered until day 8. Since high-energy phosphate metabolism is affected by the unloaded status of the heterotopically transplanted heart, irrespective of rejection, the PCr/ATP ratio appears not to be a specific marker for the detection of acute rejection in this model. In contrast, the PCr S/N ratio appears to be a specific and sensitive marker of acute rejection, but only in a late, severe stage.

The clinical value of blunting of cyclic gray level variation for the detection of acute cardiac rejection: a two-dimensional, Doppler, and videodensitometric ultrasound study

Aims of this study were to assess (1) whether videodensitometric analysis of myocardial gray-level variation can distinguish normal from rejecting transplanted hearts in a clinical setting and (2) whether this sign, used in combination with the other conventional two-dimensional and Doppler echocardiographic findings, might improve the accuracy of ultrasound techniques. Thirty heart transplant recipients (23 men; mean age 40 years; range 20 to 54 years) were studied in 87 different situations by endomyocardial biopsy and echocardiographic evaluation. Of the 87 situations, 37 ("rejectors") showed histologic evidence of rejection of mild (n = 17) or moderate (n = 10) severity and 50 ("nonrejectors") did not show rejection processes. Cyclic variation was decreased significantly in rejectors compared with nonrejectors in both the septum (15% +/- 10% versus 25% +/- 11%; p < 0.0001) and the posterior wall (19% +/- 10% versus 25% +/- 12%; p < 0.01). When a cutoff of 20% or greater of cyclic variation in the septal wall was taken as a positivity criterion, it yielded a 70% sensitivity and 70% specificity for identifying rejection. Sensitivity of conventional two-dimensional and Doppler echocardiographic signs was 51% and increased to 89%, increased by the videodensitometric criteria (p < 0.001). Specificity was 92% and decreased to 62% with videodensitometric criteria (p < 0.001). Overall diagnostic accuracy was 75% for conventional two-dimensional echocardiographic Doppler criteria alone and remained unchanged by the addition of videodensitometric criteria. In conclusion, blunting of cyclic gray-level variation induced by rejection is detectable with videodensitometric analysis. The clinical impact of this sign appears to be limited, because the resulting increase in sensitivity is counter-balanced by a reduced specificity compared with the currently available conventional ultrasound techniques.

Evoked epimyocardial electrogram for rejection diagnosis after heart transplantation

An endomyocardial electrogram (ECG) was reported to be a sensitive and practicable method for rejection monitoring after heart transplantation. Long-term follow up was limited, however, by variations of signals. The repolarization part of ECG signals vary with changes of heart rate. Both can be avoided by using pacemaker-induced signals. For stimulation and sensing of the ventricular-evoked response, a new type of electrode with fractal surface structure was used. Twenty patients undergoing heart transplantation were evaluated. Amplitudes of the depolarization and repolarization part of the ventricular-evoked response signals were analyzed and related to the degree of acute rejection according to histological findings from endomyocardial biopsy. Signals were transferred by Internet and analyzed automatically. In the case of focal moderate rejection (grade 2, International Society for Heart Transplantation grading) and higher degrees of rejection, a significant amplitude decrease was found. This sensitive non-invasive method for rejection monitoring with a high level of reliability provides the possibility of reducing the number of endomyocardial biopsies.

Noninvasive diagnosis of cardiac allograft rejection: the effect of procainamide

The surface electrocardiogram (ECG) has been used as a noninvasive technique for the diagnosis of cardiac allograft rejection. Alteration in conduction, R-wave amplitude, and rhythm have been associated with rejection. These ECG findings are modulated by the myocyte sodium channel, but are inconsistent and occur only during severe rejection episodes. The purpose of this study was to (1) characterize changes in cardiac electrophysiology during allograft rejection using the highly sensitive intramyocardial electrocardiogram and (2) determine whether pharmacological sodium channel blockade with procainamide enhances subtle ECG changes. Nine mongrel dogs underwent heterotopic heart transplantation in which four intramyocardial leads (one anteriorly and posteriorly on each ventricle) were attached. Leads exited to a subcutaneously placed ECG block which was transcutaneously accessed posttransplant to record direct intramyocardial electrocardiograms. Six animals were treated with procainamide, while three were not and served as controls. Daily measurements included the QRS, QT, and QTc intervals and the R-wave amplitude. Endomyocardial biopsies were performed weekly and also when significant decline in ECG amplitude occurred. Detailed ECG interval analysis failed to establish any correlation between conduction and rejection, even in the procainamide-treated group. Intramyocardial amplitude analysis, however, had a sensitivity of 100% and a specificity of 86% for the diagnosis of rejection. The results indicate that intramyocardial ECG interval analysis is not predictive of rejection even when prolonging conduction with procainamide. Amplitude analysis, however, remains an accurate noninvasive means for the early detection of cardiac allograft rejection and should allow more selective use of endomyocardial biopsy.