Predictors of cardiac allograft vasculopathy in pediatric heart transplant recipients

CAV remains a leading cause of late graft loss and mortality among survivors of pediatric heart transplantation. We sought to define the incidence of CAV and identify its predictors in pediatric heart transplant recipients. The OPTN/UNOS database was analyzed for pediatric recipients who underwent heart transplant between 1987 and 2011. The primary end‐point is time from heart transplantation to development of CAV (CAV‐free survival). To identify predictors of CAV‐free survival, demographic and transplant data were analyzed by the Kaplan–Meier survival method and Cox proportional hazards regression. Of 5211 pediatric heart transplant recipients with at least one‐yr follow‐up, the incidence of CAV at five, 10, and 15 yr was 13%, 25%, and 54%, respectively. Multivariate analysis found that risk of CAV was associated with the following variables: Recipient age 1–4 yr (HR 1.25), 5–9 yr (1.45), 10–18 yr (1.83), donor age >18 yr (1.34), re‐transplantation (2.14), recipient black race (1.55), and donor cigarette use (1.54). Older recipient and donor age, recipient black race, donor cigarette use, and re‐transplantation were highly associated with shorter CAV‐free survival.     

Dual-Axis Rotational Angiography is Safe and Feasible to Detect Coronary Allograft Vasculopathy in Pediatric Heart Transplant Patients: A Single-Center Experience

Coronary allograft vasculopathy (CAV) is the leading cause of graft failure in pediatric heart transplant recipients, also adding to mortality in this patient population. Coronary angiography is routinely performed to screen for CAV, with conventional single-plane or bi-plane angiography being utilized. Dual-axis rotational coronary angiography (RA) has been described, mostly in the adult population, and may offer reduction in radiation dose and contrast volume. Experience with this in the pediatric population is limited. This study describes a single-institution experience with RA for screening for CAV in pediatric patients. The catheterization database at our institution was used to identify pediatric heart transplant recipients having undergone RA to screen for CAV. Procedural data including radiation dose, fluoroscopy time, contrast volume, and procedure time were collected for each catheterization. The number of instances in which RA was not successful, ECG changes were present, and CAV was detected were also collected for each catheterization. A total of 97 patients underwent 345 catheterizations utilizing RA. Median radiation dose–area product per kilogram was found to be 341.7 (mGy cm²/kg), total air kerma was 126.8 (mGy), procedure time was 69 min, fluoroscopy time was 9.9 min, and contrast volume was 13 ml. A total of 17 (2 %) coronary artery injections out of 690 could not be successfully imaged using RA. A total of 14 patients had CAV noted at any point, 10 of whom had progressive CAV. Electrocardiographic changes were documented in a total of 10 (3 %) RA catheterizations. Procedural characteristics did not differ between serial catheterizations. RA is safe and feasible for CAV screening in pediatric heart transplant recipients while offering coronary imaging in multiple planes compared to conventional angiography.     

Paroxysmal complete atrioventricular block in pediatric heart transplant recipients following cardiac catheterization: A case series

Late‐onset paroxysmal AVB has been described as a rare complication after HT and has been associated with AR or CAV. We describe 4 pediatric HT recipients who developed paroxysmal AVB hours after routine cardiac catheterization in the absence of AR, CAV, or underlying conduction system disease. Four pediatric HT recipients who were >1 year post‐transplant had episodes of paroxysmal AVB hours after surveillance cardiac catheterization with EMB. Telemetry demonstrated high‐grade block, ranging from 2:1 AVB to complete AVB without ventricular escape for several seconds. None of the patients had significant AR or rapidly progressive CAV. Supplemental testing did not reveal underlying conduction system disease. Three of the 4 patients received permanent pacemakers, although subsequent interrogations showed minimal ventricular pacing. These pediatric HT recipients had paroxysmal AVB hours after cardiac catheterization in the absence of significant AR, CAV, or underlying conduction system disease. Subsequent pacemaker interrogations showed minimal ventricular pacing, suggesting these were isolated episodes. These cases suggest that mechanisms in addition to AR and CAV may cause paroxysmal AVB in pediatric HT recipients, warranting further investigation.     

Clinico-pathologic findings in end-stage pediatric heart transplant grafts

Abstract:  The pathologic patterns existing in end-stage pediatric heart transplant grafts may help explain the symptoms and changes seen by echocardiography and angiography in these children. Retrospective chart review and pathologic study of explanted heart grafts was performed on 12 patients that had undergone 14 heart re-transplantations. Clinical status, echocardiographic and catheterization data at the time of transplantation were correlated to the pathologic findings. At re-OHT, eight were inpatients with heart failure symptoms and/or inotropic support requirements. Echocardiograms were abnormal in all prior to re-OHT with significant diastolic dysfunction, but LVEF >40% in all but one. There was significant epicardial fibrosis in all grafts, and all had severe CAV of epicardial arteries. However, intramyocardial coronary disease was mild in nine (64%) grafts. Moderate or severe interstitial fibrosis occurred in only three grafts, and in a perivascular distribution in eight. End-stage pediatric heart allografts have severe epicardial CAV and epicardial fibrosis, with relative sparing of the myocardium. Epicardial disease with sparing of the myocardium may explain the restrictive hemodynamics and relatively preserved systolic function present in these grafts at the time of re-OHT.     

Value of soluble adhesion molecules and plasma coagulation markers in assessing transplant coronary artery disease in pediatric heart transplant recipients

BACKGROUND: With an increasing number of heart transplantations (HTx) performed in children and an extended long-term survival of these patients, the importance of transplant coronary artery disease (TCAD) rises in this group of transplant recipients. Reliable serum markers for diagnosis or non-invasive monitoring of this disease in pediatric transplant recipients are still missing. We studied the systemic expression of adhesion molecules as well as plasma coagulation markers and the occurrence of TCAD and/or rejection in pediatric heart transplant recipients. METHODS AND RESULTS: The systemic plasma levels of soluble forms of sVCAM-1 and sICAM-1, d-dimer, tissue factor (TF), prothombin fragments F(1+2), and tissue factor pathway inhibitor (TFPI) were assessed in serial venous blood samples (2-4 per patient) in 50 pediatric transplant recipients children and 63 age- and sex-matched non-transplanted controls. TCAD and rejection were diagnosed angiographically or by combined histological, echocardiographic, or clinical signs, respectively. Plasma levels of sICAM-1 and sVCAM-1, d-dimers and prothrombin fragment F(1+2) but not TF and TFPI were significantly increased in children following HTx compared with non-transplanted controls (p<0.001). Among the transplanted patients, sICAM-1 levels were significantly higher in patients with angiographically detectable TCAD than in patients without evidence of TCAD (p<0.005). Plasma sICAM-1 levels above a cutoff value of 1500 ng/mL (95.5 percentile of control values) were indicative of the presence of TCAD (odds ratio 2.7; 95% confidence interval, 1.34-5.56, p = 0.022; Fisher's exact test). Only d-dimers were found to be significantly elevated in children with signs of myocardial rejection compared with those without rejection. CONCLUSIONS: Our results suggest that plasma sICAM-1 and d-dimer levels may be potentially useful to non-invasively assess TCAD and rejection, respectively, in pediatric heart transplant recipients.     

Identification of Coronary Artery Disease in the Pediatric Cardiac Transplant Patient

Little data exist to identify pediatric patients who have developed transplant coronary artery vasculopathy (CAV). Transplant patients do not exhibit the usual signs of coronary disease, making diagnosis more difficult. The aim of this study is to assess the use of myocardial perfusion imaging to identify CAV in transplant patients and to derive an incidence of occurrence. We studied pediatric cardiac transplant recipients who have undergone myocardial perfusion imaging on a routine basis. All patients from September 1999 through November 2004 with nuclear perfusion scans were included. Twenty patients age 7–24 years (mean: 12.7), 11 male and 9 female, were studied by SPECT technetium 99M tetrofosmin imaging. Sixteen of the 20 patients were studied based on a newly instituted protocol for surveillance. Transplant was 1–14 years (mean: 7.9) earlier. Patients were also studied by stress echocardiography. Six of 20 patients (30%) had a positive perfusion scan. Ages ranged from 8 to 18 years (mean: 12). Time from transplant to positive scans ranged from 1 to 9 years (mean: 5.6). One patient showed the same perfusion defect as 2 years earlier. Five patients with positive nuclear perfusion scans showed the abnormality on the initial study; one had a previous negative study 6 months earlier. Four patients who demonstrated ischemia with exercise showed resolution at rest; the other two had no resting study. Five of these six patients with abnormal perfusion scans had negative stress echocardiograms. Only one patient identified with coronary involvement reported symptoms (exertional dyspnea). Hypertension and rejection episodes were similar in all patients and in those with positive nuclear scans. Of the six patients with positive nuclear perfusion scans, two demonstrated coronary disease at cardiac catheterization. Two patients with coronary disease at catheterization had normal nuclear perfusion scans; one of two had a normal stress echo. When three imaging modalities were used, the incidence of CAV was 30%. Symptoms in pediatric patients with CAV are seldom reported. Unfortunately, coronary arteriopathy occurs frequently and might be found as early as 1 year posttransplant. Six of 20 patients had abnormal perfusion; only 1 had any other noninvasive marker. Importantly, not all patients with CAV were identified by perfusion imaging, stress echocardiography, or coronary injection alone. Therefore, transplant patients need continued evaluation by multiple modalities for detection of developing coronary lesions.     

Empiric switch from calcineurin inhibitor to sirolimus‐based immunosuppression in pediatric heart transplantation recipients

Sirolimus is used in heart transplant patients with CAV and CNI‐induced nephropathy. However, little is known regarding the tolerability, rejection rate, and effect on renal function when used empirically in children. We describe our experience with the empiric use of a sirolimus‐based immunosuppressive regimen in pediatric heart transplantation recipients. We reviewed records of patients in whom conversion was attempted to a CNI‐free sirolimus‐based regimen. Rejection episodes and measures of renal function were recorded. We attempted to convert 20 patients, of which 16 were successful. In total, six of 20 patients (30%) experienced adverse effects. Of the 16 converted, four patients converted to sirolimus due to CNI‐induced disease (three nephropathy, one CAV), while 12 patients (mean age 5.5 yr, range 0.1–21 yr; 33% female; 33% with a history of congenital heart disease) were empirically switched to sirolimus at a mean of 2.3 yr after transplant. Follow‐up was available for a mean of 2.5 yr after conversion (range 0.5–8.3 yr). The rate of rejection while taking CNIs was 0.18 rejection episodes per patient‐year (total of five episodes), compared with 0.03 rejection episodes per patient‐year (total of one episode) while on sirolimus. Renal function, in terms of GFR, significantly improved after sirolimus conversion at latest follow‐up (from 86 ± 37 mL/min to 130 ± 49 mL/min, p = 0.02). Here, we demonstrate the potential benefit of empiric use of sirolimus in pediatric heart transplant patients in a CNI‐free regimen. Larger and longer studies are needed to further clarify risks of rejection and adverse effect profiles.     

Prevalence of hepatitis E virus infection in pediatric solid organ transplant recipients - A single-center experience

Hoerning A, Hegen B, Wingen A‐M, Cetiner M, Lainka E, Kathemann S, Fiedler M, Timm J, Wenzel JJ, Hoyer PF, Gerner P. Prevalence of hepatitis E virus infection in pediatric solid organ transplant recipients – A single‐center experience. Abstract: HEV infection appears to be an emerging disease in industrialized countries. The aim of this study was to evaluate the prevalence of HEV infection in pediatric solid organ transplant recipients. One hundred and twenty‐four pediatric recipients of liver (n = 41) or kidney (n = 83) transplants aged between one and 18 yr were screened for anti‐HEV IgG antibodies. Patients were tested for fecal HEV RNA excretion if they showed anti‐HEV seropositivity. As a control group, 108 immunocompetent pediatric patients without liver disease aged between three and 18 yr were screened for anti‐HEV IgG. HEV seroprevalence was 2.4% in renal Tx (2/83), 4.9% in liver Tx patients (2/41), and 3.2% overall (4/124). Three of these four patients were HEV RNA‐negative. In one renal transplant patient, HEV genotype 3 RNA excretion persisted and liver enzymes were elevated, indicating chronic hepatitis. In the control group, eight patients (7.4%) were HEV IgG‐positive without biochemical evidence of hepatitis. The prevalence of HEV infection in pediatric renal or liver transplant recipients is not higher compared with immunocompetent children. Chronic HEV infection with long‐term carriage of the virus may develop in pediatric transplant recipients. Autochthonous HEV infection needs to be considered in uncertain cases of hepatitis in immunosuppressed as well as immunocompetent children.     

Nonadherence is associated with late rejection in pediatric heart transplant recipients.

OBJECTIVES: The objective was to study the impact of nonadherence on late rejection after pediatric heart transplantation. STUDY DESIGN: This was a retrospective cohort study of cardiac transplant recipients surviving >6 months (n = 50). Patients were stratified by episodes of late rejection. End points were defined by cyclosporin A (CSA) level, CSA level variability, and patient admission of nonadherence. RESULTS: In 15 patients there were 49 episodes of late rejection, and 37 (76%) were associated with nonadherence. Of these patients, 7 of 15 died, and 3 of 15 had transplant coronary artery disease. Risk factors for the rejection were single-parent home, non-white, older age, and higher CSA level variability. In 35 nonrejectors there were 4 deaths from sepsis, post-transplant lymphoproliferative disease, renal failure, and encephalomyelitis. CONCLUSION: Late rejection after pediatric heart transplantation is associated with nonadherence, is common during adolescence, and is associated with poor outcome.     

Successful orthotopic heart transplantation using a donor heart with ALCAPA

With the imbalance between donation rates and potential recipients growing, transplant programs are increasingly using non‐ideal organs from so‐called marginal donors. This is the first reported case of the intentional use of a donor heart with ALCAPA. The recipient was aged one yr with restrictive cardiomyopathy who had been supported with BiVAD for over six months. Function of the donor left ventricle was shown to be well preserved, with no obvious signs of ischemia, except for a fibrotic layer on the anterolateral papillary muscle of the mitral valve. To prevent coronary steal, the anomalous left coronary artery ostium from the MPA was oversewn prior to implantation. The transplanted heart spontaneously regained sinus rhythm immediately following cross‐clamp release and showed good contractility from the first postoperative echocardiogram. The patient continues to do well 18 months post‐transplant, with excellent function on echocardiography, and good flow on coronary angiography.     

Prevalence of renal dysfunction in tacrolimus‐treated pediatric transplant recipients: A systematic review

Renal dysfunction after non‐renal transplantation in adult tacrolimus‐treated transplant patients is well documented. Little is known about its prevalence in children. Age‐related changes in both disposition and effect of tacrolimus as well as renal function may preclude extrapolation of adult data to children. To systematically review the literature on renal dysfunction in non‐renal pediatric transplant recipients treated with tacrolimus. PubMed/Medline, Embase, and Google were searched from their inception until April 19, 2012, with the search terms “tacrolimus,” “renal function,” “transplantation,” and “children.” Eighteen of 385 retrieved papers were considered relevant. Twelve dealt with liver, four with heart transplant, one with heart and lung transplant, and one with intestinal recipients. Reported prevalences of mild and severe chronic kidney disease ranged from 0% to 39% and 0% to 71.4%, respectively, for liver, and from 22.7% to 40% and 6.8% to 46%, respectively, for heart and/or lung transplant recipients. Ranges remained wide after adjusting for follow‐up time and disease severity. Possible explanations are inclusion bias and definitions used for renal dysfunction. A considerable proportion of pediatric non‐renal transplant patients who receive tacrolimus‐based immunosuppression, appear to suffer from chronic kidney disease. This conclusion warrants further research into the real risk, its risk factors, and individualization of immunosuppressant therapy.     

Restrictive hemodynamics are present at the time of diagnosis of allograft coronary artery disease in children

Clinical recognition of allograft coronary artery disease (ACAD) is challenging. We examined whether right heart hemodynamics can aid its diagnosis in pediatric recipients. We retrospective analyzed hemodynamic data of recipients with ACAD versus age and date-of-transplant matched controls. From 1982-2001, 18 cases fulfilled study entry criteria. Median age at transplant was 12 years for subjects and 8 years for controls. Median time to diagnosis of ACAD was 65 months (14.5-124 months) and 67 months (16-140 months) to arteriography for controls. The median right ventricular end-diastolic pressure (RVEDP) at diagnosis was 11.0 vs. 6.0 mmHg for controls (p = 0.003). Pulmonary capillary wedge pressure (PCWP) at diagnosis was 14.0 vs. 8.0 mmHg for controls (p = 0.001). When subdivided by severity of ACAD, the difference was greater in the moderate/severe group. Compared to the previous catheterization (median interval 10 months for subjects, 12.0 for controls ), there was an increase of 4.0 mmHg in RVEDP in ACAD subjects (n = 13, p = .003) versus 0 mmHg in controls (p = 0.042), and an increase in PCWP of 5.5 in subjects (p = .002) versus 0 mmHg in controls (p = 0.066). The presence of elevated filling pressures plus an interim increase should alert to the presence of ACAD and help guide further investigation.     

An apparent case of undiagnosed donor Kawasaki disease manifesting as coronary artery aneurysm in a pediatric heart transplant recipient

We present a case of coronary ectasia and LAD coronary artery aneurysm with angiographic characteristics of Kawasaki disease in a three‐yr‐old girl two‐yr status post‐orthotopic heart transplant. Coronary anomalies were noted during initial screening coronary angiography two yr after transplant. Subsequent review of the donor echocardiogram revealed that the LMCA had been mildly dilated prior to transplant. In the absence of any symptoms consistent with Kawasaki disease in the transplant recipient, this appears to be a case of Kawasaki disease in the organ donor manifesting with coronary anomalies in the transplant recipient. The patient has done well clinically, and repeat coronary angiography has revealed partial regression of coronary anomalies. Given multiple reports in the literature of persistent abnormalities of coronary artery morphology and function after Kawasaki disease, close monitoring is warranted, with consideration of potential coronary protective medical therapies.     

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 HT x and may aid in the detection of rejection and CAV . Strain parameters have not been well defined in the pediatric HT x population. This study aimed to describe strain in pediatric HT x recipients compared to controls and assess changes over time. All pediatric HT x 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 HT x 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‐HT x, 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‐HT x 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.     

Transplant coronary artery disease in children

Transplant coronary artery disease is an accelerated vasculopathy that occurs in adult and pediatric heart transplant recipients, and it is a leading cause of death among late survivors. This form of coronary disease, also known as graft coronary disease, differs from classical atherosclerosis in both histologic and angiographic features and it progresses much more rapidly. Although its pathogenesis has not been determined precisely, both immune and non-immune mechanisms appear to contribute, with a final common pathway of endothelial injury due to both antigen-dependent and antigen-independent factors. Many investigators believe both cellular and/or humoral rejection play a direct role in its etiology. In children the true incidence of the condition is unknown, although a multicenter survey identified 58 (7.2%) patients among 815 transplant recipients at 17 centers. Detection remains difficult. In the past, non-invasive methods have been unsatisfactory, although recent experience has suggested that Dobutamine stress echocardiography may be promising. Once a diagnosis is made, treatment has been limited to palliation by either intracoronary interventional procedures or surgical coronary bypass grafting, and to cardiac retransplantation with its own set of problems. Current efforts are directed at prevention. Blood levels of cholesterol have been reduced in adults treated with Pravastatin, but there have been no reports of its use in children. In adults additional agents with potential benefit have included calcium channel blockers and ACE inhibitors. A multicenter trial in children is needed to answer the many remaining questions regarding transplant coronary disease in this age group.     

Immune monitoring of pediatric heart transplant recipients through serial donor specific antibody testing — An initial experience and review of the literature

Heart transplantation is the best therapy for patient with end stage heart failure from cardiomyopathy or congenital heart disease that is not amenable to further surgical palliation. However, the development of rejection, cardiac allograft vasculopathy, and graft failure limit long term survival. Standard tools to assess for these complications include Echo, ECG, endomyocardial biopsy, and coronary angiography. However, the measurement of anti-HLA antibodies before and after transplantation is emerging in the clinical management of pediatric heart transplant recipients. It has been demonstrated that the presence of anti-HLA antibodies prior to transplantation and the development of de novo donor specific antibodies are both associated with poor outcomes. Detection of donor specific antibodies may be useful to monitor highly sensitized patients post transplant and to diagnose and guide clinical decision making in the treatment of antibody mediated rejection. Immunologic monitoring for the presence of these antibodies can be integral to ongoing surveillance. This paper will review the role of the immune system in heart transplantation, discuss concepts of pretransplant allosensitization and post transplant donor specific antibodies, and, finally will review clinical scenarios in which immunologic monitoring through donor specific antibody testing can be helpful.     

Long-Term Outcome of Palliation with Internal Pulmonary Artery Bands After Primary Heart Transplantation for Hypoplastic Left Heart Syndrome

The purpose of this study was to describe the long-term outcome of infants with hypoplastic left heart syndrome (HLHS) who underwent placement of internal pulmonary artery bands as part of a transcatheter palliation procedure followed by primary heart transplantation. Transcatheter palliation included stenting of the ductus arteriosus, decompression of the left atrium by atrial septostomy, and internal pulmonary artery band placement. Cardiac hemodynamics, pulmonary artery architecture, and pulmonary artery growth since transplantation are described. Nine infants with HLHS had internal pulmonary artery bands placed and underwent successful heart transplant. No infant required reconstruction of the pulmonary arteries at the time of transplant. At 1 year after transplant, all of the recipients had normal mean pulmonary artery pressure, pulmonary vascular resistance, and transpulmonary gradient. Pulmonary angiography performed at 1 year after transplant demonstrated no distortion of pulmonary artery anatomy with significant interval growth of the branch pulmonary arteries. There was 100% survival to hospital discharge after transplant in this cohort of infants. Transcatheter placement of internal pulmonary artery bands for HLHS offers protection of the pulmonary vascular bed while preserving pulmonary artery architecture and growth with good long-term outcome.     

Outcome of Acute Graft Rejection Associated with Hemodynamic Compromise in Pediatric Heart Transplant Recipients

We sought to analyze the outcome of hemodynamically significant acute graft rejection in pediatric heart transplant recipients from a single-center experience. Acute graft rejection remains a major cause of morbidity and mortality for patients who undergo orthotopic heart transplantation and has been associated with the severity of the rejection episode. A retrospective review of all children experiencing a hemodynamically significant rejection episode after orthotopic heart transplantation was performed. Fifty-three patients with 54 grafts had 70 rejection episodes requiring intravenous inotropic support. Forty-one percent of these patients required high-dose inotropic support, with the remaining 59% of patients requiring less inotropic support. Overall graft survival to hospital discharge was 41% for patients in the high-dose group compared to 94% in the low-dose group. Six-month graft survival in patients who required high-dose inotropes remained at 41% compared to 44% in the low-dose group. Hemodynamically significant acute graft rejection in pediatric heart transplant recipients is a devastating problem with poor short- and long-term outcomes. Survival to hospital discharge is dismal in patients who require high-dose inotropic support. In contrast, survival to discharge is quite good in patients who require only low-dose inotropic support; however, six-month graft survival in this group is low secondary to a high incidence of graft failure related to worsening or aggressive transplant coronary artery disease.