Strain and strain rate imaging using speckle tracking in acute allograft rejection in children with heart transplantation

Rejection surveillance in pediatric heart transplant recipients: Critical reflection on the role of frequent and long-term routine surveillance endomyocardial biopsies and comprehensive review of non-invasive rejection screening tools

BACKGROUND

Despite significant medical advances in the field of pediatric heart transplantation (HT), acute rejection remains an important cause of morbidity and mortality. Endomyocardial biopsy (EMB) remains the gold-standard method for diagnosing rejection but is an invasive, expensive, and stressful process. Given the potential adverse consequences of rejection, routine post-transplant rejection surveillance protocols incorporating EMB are widely employed to detect asymptomatic rejection. Each center employs their own specific routine rejection surveillance protocol, with no consensus on the optimal approach and with high inter-center variability. The utility of high-frequency and long-term routine surveillance biopsies (RSB) in pediatric HT has been called into question.

METHODS

Sources for this comprehensive review were primarily identified through searches in biomedical databases including MEDLINE and Embase.

RESULTS

The available literature suggests that the diagnostic yield of RSB is low beyond the first year post-HT and that a reduction in RSB intensity from high-frequency to low-frequency can be done safely with no impact on early and mid-term survival. Though there are emerging non-invasive methods of detecting asymptomatic rejection, the evidence is not yet strong enough for any test to replace EMB.

CONCLUSION

Overall, pediatric HT centers in North America should likely be doing fewer RSB than are currently performed. Risk factors for rejection should be considered when designing the optimal rejection surveillance strategy. Noninvasive testing including emerging biomarkers may have a complementary role to aid in safely reducing the need for RSB.

Assessment of Acute Rejection by Global Longitudinal Strain and Cardiac Biomarkers in Heart-Transplanted Patients

Aims

The aim of this study was to evaluate left ventricular global longitudinal strain (LVGLS), N-terminal pro brain natriuretic peptide (Nt-ProBNP), and Troponin T as non-invasive markers for acute cellular rejection (ACR) diagnosis and severity assessment after heart transplantation (HTx).

Methods

We retrospectively included all HTx patients transplanted from 2013 to 2019. At each visit, the patients were subjected to endomyocardial biopsy (EMB), measurement of Nt-ProBNP and Troponin T, and protocoled echocardiography with assessment of LVGLS. Sudden drop in graft function (SDGF) was defined as a drop in LVGLS ≥-2% in combination with either an increase in Troponin T ≥20% or Nt-ProBNP ≥30% compared with levels at the latest visit.

Results

We included 1,436 EMBs from 83 HTx patients. The biopsies were grouped as 0R (n = 857), 1R (n = 538), and ≥2R (n = 41). LVGLS was lower and Troponin T and Nt-ProBNP higher in the 2R group than in the 0R and 1R groups (LVGLS: -12.9 ± 3.8% versus -16.9 ± 3.1% and -16.1 ± 3.3%; Troponin T: 79 [33;230] ng/l versus 27 [13;77] ng/l and 27 [14;68] ng/l; Nt-ProBNP: 4,174 [1,095;9,510] ng/l versus 734 [309;2,210] ng/l and 725 [305;2,082], all p < 0.01). A SDGF was seen at 45 visits of which 19 had ≥2R ACR. EMBs showed ACR in 20 cases without SDGF. Finally, neither was SDGF seen nor did the EMB show rejection in 1,136 cases. Thus, the sensitivity of SDGF for ≥2R ACR detection was 49% (32–65) and specificity 98% (97–99). The positive predictive value (PPV) was 42% (31–55) and the negative predictive value (NPV) 98% (98–99). The diagnostic value improved in a sub-analysis excluding EMBs within 3 months after HTx, clinically interpreted false positive ≥2R ACR cases, and cases with ≥2R ACR who recently (<2 weeks) were treated with intravenous methylprednisolone due to ≥2R ACR (sensitivity 75% (48–93), specificity 97% (96–98), NPV 99% (99–100), and PPV 39% (27–52).

Conclusions

Patients with ≥2R ACR have lower LVGLS and higher Troponin T and Nt-ProBNP than patients without 2R rejection. A non-invasive model combining changes in LVGLS and Troponin T or Nt-ProBNP showed excellent negative predictive value and moderate sensitivity and may be used as a gatekeeper to invasive biopsies after HTx.

Changes in circumferential strain can differentiate pediatric heart transplant recipients with and without graft rejection

BACKGROUND

Routine surveillance protocols rely heavily on endomyocardial biopsy (EMB) for detection of rejection in pediatric heart transplant recipients. More sensitive echocardiographic tools to assess rejection may help limit the number of EMBs. This study compared changes in left ventricular (LV) strain in patients who had rejection versus those who did not.

METHODS

A single center retrospective review was conducted between 2013 and 2020. Patients were categorized based on rejection history. Echocardiograms were evaluated at the time of 2 consecutive EMBs; in the rejection group, the second echocardiogram was collected at the time of a rejection episode. Conventional measures of LV function and speckle-tracking echocardiography-derived longitudinal (LS) and circumferential strain (CS) were measured.

RESULTS

17 patients were in the non-rejection group and 17 were in the rejection group (30 total rejection episodes). The rejection group was older at the time of transplant (12.5 vs. 1.3 years, p = .01). A decline in CS was seen in the rejection group at the second echocardiogram [-18.5 (IQR -21.5, -14.6) to -15.7 (IQR -19.8, -13.2)] while CS improved in the non-rejection group [-20.8 (IQR -23.9, -17.8) to -23.9 (IQR -24.9, -20.1)]. This difference in change reached significance (p = .02). A similar pattern was seen in LS that neared significance (p = .06). There was no significant difference in ejection fraction change (p = .24).

CONCLUSIONS

Patients in the non-rejection group displayed improvement in CS between echocardiograms while patients in the rejection group showed subsequent decline. Worsening of LV CS may help identify acute rejection in the early post-transplant period.

Speckle-tracking-based global longitudinal and circumferential strain detect early signs of antibody-mediated rejection in heart transplant patients

AIMS

Acute rejection is an important cause of mortality after heart transplant (HTx), but symptoms develop only when myocardial damage is already extensive. We sought to investigate if echocardiographic parameters can detect and predict an acute cellular rejection (ACR) or antibody-mediated rejection (AMR) episode in HTx patients.

METHODS AND RESULTS

Data of 403 consecutive HTx recipients between 2003 and 2020 from our centre were reviewed. Patients with severe ACR (n = 10) and AMR (n = 7) were identified. Each HTx patient presenting with rejection was matched to a control HTx patient. Echocardiographic variables from the moment of rejection and 3, 6, and 12 months before were analysed and compared among groups. At acute rejection episode, patients with rejection had lower values of global longitudinal strain (GLS), global circumferential strain (GCS), and left ventricular ejection fraction (LVEF) compared to controls. HTx patients with AMR showed a progressive decline of GLS and GCS in the months preceding acute rejection, while controls and ACR patients had stable strain values except for the moment of rejection. In our cohort, a GLS cut-off lower than 15.5% and a GCS cut-off lower than 15.2% could distinguish with a sensitivity and specificity of 100.0% AMR from controls 3 months before rejection. LVEF and other conventional echo parameters could not differentiate among groups.

CONCLUSION

GLS and GCS show a progressive decrease months before AMR becomes clinically apparent. Our data suggest that global strain assessment by echocardiography allows an early detection of a developing AMR, which could improve the clinical management of HTx patients.

Imaging of Cardiac Transplantation: An Overview

Heart transplantation (HTx) remains the optimal treatment for selected patients with end-stage advanced heart failure. However, survival is limited early by acute rejection and long term by cardiac allograft vasculopathy (CAV). Even though the diagnosis of rejection is based on histology, cardiac imaging provides a pivotal role for early detection and severity assessment of these hazards. The present review focuses on the use and reliability of different invasive and non-invasive imaging modalities to detect and monitor CAV and rejection after HTx. Coronary angiography remains the corner stone in routine CAV surveillance. However, angiograms are invasive and underestimates the CAV severity especially in the early phase. Intravascular ultrasound and optical coherence tomography are invasive methods for intracoronary imaging that detects early CAV lesions not evident by angiograms. Non-invasive imaging can be divided into myocardial perfusion imaging, anatomical/structural imaging and myocardial functional imaging. The different non-invasive imaging modalities all provide clinical and prognostic information and may have a gatekeeper role for invasive monitoring. Acute rejection and CAV are still significant clinical problems after HTx. No imaging modality provides complete information on graft function, coronary anatomy and myocardial perfusion. However, a combination of invasive and non-invasive modalities at different stages following HTx should be considered for optimal personalized surveillance and risk stratification.

A novel model of constrictive pericarditis associated with myocardial fibrosis in rats

An efficient animal model is fundamental for studies on the underlying mechanisms of constrictive pericarditis (CP). A novel CP rat model was established by pericardial injection composing of lipopolysaccharides (LPS) and talcum powder without thoracotomy. Pathological changes were confirmed by histological staining. E-flow Doppler of mitral valve, tissue Doppler E' in the medial mitral annular (E'_sep ) and the lateral mitral annular (E'_lat ) were measured to assess ventricular filling function. Circumferential, longitudinal, and radial strains (SC, SL and SR) and the respective strain rates (SrC, SrL and SrR) were analyzed in interventricular septum (IVS) and left ventricular free wall (LVFW). Rat cardiac fibroblasts (CFs) were treated with LPS. The activation of transforming growth factor β1 (TGF-β1) was confirmed by Q-PCR and western blot assays. Thickening of pericardium and fibrosis in pericardium and subepicardial myocardium were showed in the model group. Diastolic dysfunction in the CP group was indicated by decreased E'_lat and E'_lat /E'_sep , increased E/E'_lat , decreased E_FW of SrC and SrL, increased A_IVS and decreased E/A of SrC, SrL and SrR. Systolic dysfunction was indicated by decreased SC_FW and SL_FW in CP rats. The levels of TGF-β1, p-Smad2/3, α-smooth muscle actin (α-SMA), and collagen-I/III (COL-I/III) were increased in the CP group. The increased TGF-β1 that induced by LPS activated and phosphorylated Smad2/3 resulting in the secretion of α-SMA and COL-I/III. This model is of vital importance in studying the pathogenesis of CP.

Assessment of biventricular function by three-dimensional speckle-tracking echocardiography in clinically well pediatric heart transplantation patients

BACKGROUND

The biventricular function plays an important role in the prognosis of pediatric heart transplantation (HTx) patients. Therefore, in this study, we aimed to evaluate the biventricular function of pediatric HTx patients by three-dimensional (3D) speckle-tracking echocardiography (3D-STE).

METHODS

We enrolled 30 clinically well pediatric HTx patients and 30 healthy controls with a similar distribution of sex and age to the HTx. All participants underwent comprehensive two-dimensional (2D) and 3D echocardiography. Left ventricular (LV) global longitudinal strain (GLS), global circumferential strain (GCS), left and right ventricular ejection fraction (LVEF and RVEF, respectively), and right ventricular free wall longitudinal strain (RV FWLS) were acquired by 3D-STE. Moreover, the correlations between strains and clinical data were explored.

RESULTS

Compared with controls, LV GLS was decreased in pediatric HTx patients (P < .05), while LV GCS and LVEF showed no difference. LV GLS showed a weak correlation with cold ischemic time in HTx group (r = 0.396, P < .05). Meanwhile, RVEF and RV FWLS were significantly lower in the HTx group (P < .05). In the HTx group, RV FWLS showed a weak correlation with the preoperative mean pulmonary artery pressure (r = 0.420, P < .05) and postoperative pulmonary artery systolic pressure (r = 0.465, P < .05).

CONCLUSION

The 3D-biventricular mechanical functions were decreased in clinically well pediatric HTx patients. The provided characteristics and appropriate normal values of biventricular mechanical functions can be the basis in subsequent studies in the pediatric HTx patients.

Non-invasive cardiac allograft rejection surveillance: reliability and clinical value for prevention of heart failure

Allograft rejection-related acute and chronic heart failure (HF) is a major cause of death in heart transplant recipients. Given the deleterious impact of late recognized acute rejection (AR) or non-recognized asymptomatic antibody-mediated rejection on short- and long-term allograft function improvement of AR surveillance and optimization of action strategies for confirmed AR can prevent AR-related allograft failure and delay the development of cardiac allograft vasculopathy, which is the major cause for HF after the first posttransplant year. Routine non-invasive monitoring of cardiac function can improve both detection and functional severity grading of AR. It can also be helpful in guiding the anti-AR therapy and timing of routine surveillance endomyocardial biopsies (EMBs). The combined use of EMBs with non-invasive technologies and methods, which allow detection of subclinical alterations in myocardial function (e.g., tissue Doppler imaging and speckle-tracking echocardiography), reveal alloimmune activation (e.g., screening of complement-activating donor-specific antibodies and circulating donor-derived cell-free DNA) and help in predicting the imminent risk of immune-mediated injury (e.g., gene expression profiling, screening of non-HLA antibodies, and circulating donor-derived cell-free DNA), can ensure the best possible surveillance and management of AR. This article gives an overview of the current knowledge about the reliability and clinical value of non-invasive cardiac allograft AR surveillance. Particular attention is focused on the potential usefulness of non-invasive tools and techniques for detection and functional grading of early and late ARs in asymptomatic patients. Overall, the review aimed to provide a theoretical and practical basis for those engaged in this particularly demanding up-to-date topic.

Early Acute Graft Rejection in a Heart Transplanted Child with Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is the most common type of cardiomyopathy in children. Heart transplantation is considered standard therapy in dilated cardiomyopathy with end-stage heart failure. We present a case of a 15-year-old patient diagnosed with DCM in the neonatal period, who underwent heart transplantation for end-stage heart failure. Despite the use of induction therapy, the endomyocardial biopsy performed at two weeks post-transplant revealed mixed moderate cellular (2R) and humoral (pAMR2) allograft rejection. Aggressive rejection treatment was initiated with good outcome. Besides endomyocardial biopsy, advanced echocardiography can also be a valuable noninvasive tool for rejection assessment.

Tissue Doppler velocities for ruling out rejection in heart transplant recipients in the context of myocardial strain imaging: a multivariate, prospective, single-center study

To investigate the value of tissue Doppler velocities for ruling out treatment-requiring acute cellular rejection (TR-ACR), in the context of myocardial deformation analysis performed by means of speckle tracking echocardiography. We performed serial echocardiograms in 37 heart transplant recipients in their first year post-transplantation within 3 h of the routine surveillance endomyocardial biopsies (EMB). The association of the sum of lateral mitral annulus systolic (s') and early diastolic (e') velocities, in absolute values, measured by tissue Doppler echocardiography (s'+ e'), with TR-ACR (ACR grade ≥ 2R) was investigated by multivariate analysis, including classic echocardiographic parameters and myocardial deformation variables. A total of 251 pairs of EMB and echo exams were performed, 35 (14%) with rejection grade ≥ 2R (TR-ACR). s' + e' was independently associated to TR-ACR (OR 0.80, 95%CI 0.72-0.89, p < 0.0005), with a C statistic of 0.79 (95%CI 0.71-0.87, p < 0.0005) by ROC curve analysis. An  s'+ e' value ≥ 23 cm/s, present in 43% of studies, had a negative predictive value of 98% for ruling out TR-ACR. Moreover, in the same patients, s'+ e' significantly decreased when TR-ACR occurred after a study without this condition (- 3.7 ± 3.3 cm/s, p = 0.003), but it was similar when rejection status was the same in the present versus the previous study. A drop in s'+ e' value < 2.7 cm/s from the previous echocardiogram, had a 99% negative predictive value for ruling out TR-ACR. Tissue Doppler velocities, a widely available echo parameter, were found to be a valuable marker for ruling out TR-ACR in this multivariate study which included myocardial deformation variables.

Two-dimensional systolic speckle tracking echocardiography provides a noninvasive aid in the identification of acute pediatric heart transplant rejection

BACKGROUND

Acute rejection is an important cause of morbidity and mortality in the pediatric heart transplant (HT) population. A reliable noninvasive method for diagnosis of clinical rejection could substantially reduce these negative outcomes.

OBJECTIVE

Evaluate left ventricular (LV) global longitudinal strain (GLS), and global circumferential strain (GCS) as early noninvasive indicators of acute pediatric HT rejection.

METHODS

An 18-month prospective cohort study involving 61 patients evaluated absolute change in peak global systolic strain (GLS and GCS) from enrollment (baseline) to next planned clinical encounter (follow-up) or rejection. Acute rejection defined as a biopsy of grade ≥ 2R or treatment with enhanced immunosuppression by the transplant team, blinded to strain analysis. Two patient cohorts three months post HT without evidence of rejection at enrollment were identified. The study cohort experienced rejection. The control cohort remained free from rejection on follow-up. Two-way analysis of variance (ANOVA) models evaluated change in GLS and GCS by cohort group and time.

RESULTS

Applying exclusion criteria, 51 patients enrolled in the control cohort and 10 in the study cohort. The study cohort's mean GLS declined 33% from baseline to rejection (P < .001) and mean GCS declined 16.6% (P = .021). No significant change from baseline to follow-up was seen in the control cohort. A threshold absolute GLS value of 16.1% identified acute rejection with 100% sensitivity and 98% specificity (Likelihood Ratio, [LR] 51).

CONCLUSION

Noninvasive global longitudinal strain was sensitive and specific in the identification of acute clinical rejection in pediatric HT recipients.

Multi-modal imaging of the pediatric heart transplant recipient

The assessment of pediatric patients after orthotropic heart transplantation (OHT) relies heavily on non-invasive imaging. Because of the potential risks associated with cardiac catheterization, expanding the role of non-invasive imaging is appealing. Echocardiography is fast, widely available, and can provide an accurate assessment of chamber sizes and function. Advanced echocardiographic methods, such as myocardial deformation, have potential to assess for acute rejection or cardiac allograft vasculopathy (CAV). While not currently part of routine care, cardiac magnetic resonance imaging (CMR) and computed tomography may potentially aid in the detection of graft complications following OHT. In particular, CMR tissue characterization holds promise for diagnosing rejection, while quantitative perfusion and myocardial late gadolinium enhancement may have a role in the detection of CAV. This review will evaluate standard and novel methods for non-invasive assessment of pediatric patients after OHT.

Left ventricular adaptation following orthotopic heart transplantation in children: A speckle tracking echocardiographic imaging study

BACKGROUND

Evolution of left ventricle (LV) function in the pediatric OHT population has not been well described. Our hypothesis was that, in children following OHT without any rejection, there would be progressive normalization of LV size and function over 2 years.

METHODS

LV function was evaluated using STE and conventional echo parameters at five time points in pediatric OHT patients without any rejection in the first 2 years following OHT and normal controls. LV global peak systolic longitudinal strain (LVPLS) and strain rate, LV peak systolic radial and circumferential strain (LVRS and LVCS), and strain rate were analyzed.

RESULTS

We had twenty two patients with median age at OHT of 1.27 years ( IQR 0.19, 5.6 years). The LVPLS (mean ± SD) was abnormal in the post-OHT echocardiograms at 1 week (-12.4 ± 3.7) and 1 month (-13.9 ± 3.7) and significantly improved at 6 months (-15.8 ± 3.2), 1 year (-15.7 ± 3.1), and 2 years (-17.8 ± 2.8). However, LVPLS remained below the normal group even at 2 years following OHT (-21.3 ± 1.76).

CONCLUSION

In children following OHT, despite the absence of rejection, strain values are significantly impaired in the initial months, improve progressively over the first 2 years but remain abnormal compared with healthy controls.

Changes in left ventricular strain parameters following pediatric heart transplantation

STE is increasingly utilized to assess strain in a variety of pathologies. Strain measurements have demonstrated utility following HTx and may aid in the detection of rejection and CAV. Strain parameters have not been well defined in the pediatric HTx population. This study aimed to describe strain in pediatric HTx recipients compared to controls and assess changes over time. All pediatric HTx recipients with available echocardiograms (2004-2015) without rejection or CAV were identified. Longitudinal and circumferential strain was measured at <1 month, 1 year, 3 years, and 5 years post-transplant and compared to controls. A total of 218 echocardiograms were analyzed in 79 HTx recipients. At <1 month post-transplant, there was a significant decrement in longitudinal strain (GLS -14.6 vs -19.2, P < .001) with concurrent augmentation of circumferential strain (GCS -27.3 vs -24.3, P = .005). By 1 year post-HTx, all strain parameters normalized and were not significantly different from the control population. In the absence of graft complications, strain parameters did not change up to 5 years post-transplant. Abnormal longitudinal strain parameters are present in the early post-HTx period with a compensatory increase in circumferential strain. These changes normalize by 1 year post-transplant and do not change over time in the absence of graft complications.

Feasibility and interpretation of global longitudinal strain imaging in pediatric heart transplant recipients

Evaluation of myocardial mechanics after heart transplant is important in monitoring allograft function and identifying rejection. Speckle tracking global longitudinal strain (GLS) may be more sensitive to early regional changes from rejection. This study aimed to determine feasibility of GLS in pediatric hearts during surveillance echocardiograms, compare their GLS to published norms (-18% to -22%), and assess association of GLS with other indices of graft function. Retrospective review of transplant echocardiograms from 2013 to 2014. Philips QLAB was used for post-acquisition GLS analysis. Multiple linear regression was used to assess the association of GLS with echocardiographic/catheterization indices, and B-type natriuretic peptide (BNP). Forty-seven patients (84 studies) were included. Calculation of GLS was feasible in 82 studies (97%) with inter- and intra-observer variability of 0.71 and 0.69. Patients (n=9) with rejection had GLS of -16.4% (SD=3.5%) compared to those without [-16.8% (SD=3.7%)]. GLS worsened linearly with increasing Ln(BNP) (P=<.001), left ventricular volume in diastole (P=<.001), septal a' wave (P=<.001), and pulmonary capillary wedge pressure (P=<.001). Speckle tracking-based GLS is feasible and reproducible in pediatric heart recipients and is reduced at baseline. The role of GLS and BNP in detecting early systolic dysfunction warrants further investigation.

Alteration of Cardiac Deformation in Acute Rejection in Pediatric Heart Transplant Recipients

The objective of this study is to assess changes in cardiac deformation during acute cellular- and antibody-mediated rejection in pediatric HT recipients. Pediatric HT recipients aged ≤18 years with at least one episode of biopsy-diagnosed rejection from 2006 to 2013 were included. Left ventricular systolic S (SS) and SR (SSr) data were acquired using 2D speckle tracking on echocardiograms obtained within 12 h of right ventricular endomyocardial biopsy. A mixed effect model was used to compare cardiac deformation during CR (Grade ≥ 1R), AMR (pAMR ≥ 2), and mixed rejection (CR and AMR positive) versus no rejection (Grade 0R and pAMR 0 or 1). A total of 20 subjects (10 males, 50%) with 71 rejection events (CR 35, 49%; AMR 21, 30% and mixed 15, 21%) met inclusion criteria. The median time from HT to first biopsy used for analysis was 5 months (IQR 0.25-192 months). Average LV longitudinal SS and SSr were reduced significantly during rejection (SS: -17.2 ± 3.4% vs. -10.7 ± 4.5%, p < 0.001 and SSr: -1.2 ± 0.2 s^- 1 vs. -0.9 ± 0.3 s^- 1; p < 0.001) and in all rejection types. Average LV short-axis radial SS was reduced only in CR compared to no rejection (p = 0.04), while average LV circumferential SS and SSr were reduced significantly in AMR compared to CR (SS: 18.9 ± 4.2% vs. 20.8 ± 8.8%, p = 0.03 and SSr: 1.35 ± 0.8 s^- 1 vs. 1.54 ± 0.9 s^- 1; p = 0.03). In pediatric HT recipients, LV longitudinal SS and SSr were reduced in all rejection types, while LV radial SS was reduced only in CR. LV circumferential SS and SSr further differentiated between CR and AMR with a significant reduction seen in AMR as compared to CR. This novel finding suggests mechanistic differences between AMR- and CR-induced myocardial injury which may be useful in non-invasively predicting the type of rejection in pediatric HT recipients.

Strain Imaging Echocardiography: What Imaging Cardiologists Should Know

Despite recent advances in clinical imaging, echocardiography remains as the most accessi-ble and reliable noninvasive. Since knowledge of left ventricular systolic function remains so critically important in determining prognosis; every effort should be made to prevent subjective estimations. The advent of strain imaging echocardiography now offers a readily available and portable imaging tool that not only offers an objective characterization of myocardial dynamics; but also allows for early detection of subclinical left ventricular dysfunction. This review outlines the basic concepts of strain imaging to better understand the mechanism of myocardial function as well their applicability in the least common cardiac diagnosis among current clinical practice.

Decline in ventricular function as a result of general anesthesia in pediatric heart transplant recipients

Echocardiography is frequently performed under anesthesia during procedures such as cardiac catheterization with EMB in pediatric HTx recipients. Anesthetic agents may depress ventricular function, resulting in concern for rejection. The aim of this study was to compare ventricular function as measured by echocardiography before and during GA in 17 pediatric HTx recipients. Nearly all markers of ventricular systolic function were significantly decreased under GA, including EF (-4.2% ±1.2, P < .01) and RV FAC (-0.05 ± 0.02, P = .04). Subjects in the first post-transplant year (n = 9) trended toward a more significant decrease in EF vs those beyond the first post-transplant year (n = 8; -6.0% ±1.2 vs -2.1 ± 2.0, P = .1). This information quantifies a decline in biventricular function that should be expected in pediatric HTx recipients while under GA and can assist the transplant clinician in avoiding unnecessary treatment of transient GA-induced ventricular dysfunction.

Evaluation of Acute Rejection by Measuring Strain and Strain Rate in Children With Heart Transplant: A Preliminary Report

OBJECTIVES

Asymptomatic rejection after heart transplant is difficult to detect by noninvasive methods. The present study investigated the efficacy of echocardiographic strain and the strain rate imaging method in detecting rejection after pediatric heart transplant.

MATERIALS AND METHODS

Fourteen pediatric patients with heart transplant were examined both with endomyocardial biopsy and strain imaging. Patients were divided into 2 groups: group 1 included patients with rejection, and group 2 included patients without rejection. Patients underwent endomyocardial biopsy at regular intervals. Regional systolic function was evaluated by longitudinal myocardial peak systolic values of strain and of strain rate. Differences between the 2 groups were assessed with unpaired t test or Mann-Whitney U test.

RESULTS

Acute rejection was detected in 7 patients (4 were female patients). Cardiac diagnosis was restrictive cardiomyopathy in 3 patients, dilated cardiomyopathy in 3 patients, and complex congenital heart disease in 1 patient. After heart transplant, 6 patients had rejection once and 1 patient had rejection twice. Evaluation of biopsy samples revealed grade IB rejection in all patients in group 1. Systolic functions of the 6 patients were determined as normal in standard echocardiographic examination. There were no significant differences in deformation and deformation rates between group 1 and 2 except in midseptal region (P < .05).

CONCLUSIONS

One of the most significant complications in patients with heart transplant is rejection. Our results suggested that myocardial strain imaging may be valuable in defining low-grade rejection.