Tissue Doppler-derived diastolic myocardial velocities are abnormal in pediatric cardiac transplant recipients in the absence of endomyocardial rejection

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 left-ventricular diastolic function in pediatric intensive-care patients: a review of parameters and indications compared with those for adults

BACKGROUND

The incidence of diastolic heart failure has increased over time. The evaluation of left-ventricular diastolic function is complex, ongoing, and remains poorly performed in pediatric intensive-care patients. This study aimed to review the literature and to provide an update on the evaluation of left-ventricular diastolic function in adults and children in intensive care.

DATA SOURCES

We searched data from PubMed/Medline. Thirty-two studies were included. Four pragmatic questions were identified: (1) What is the physiopathology of diastolic dysfunction? (2) Which tools are required to evaluate diastolic function? (3) What are the echocardiographic criteria needed to evaluate diastolic function? (4) When should diastolic function be evaluated in pediatric intensive care?

RESULTS

Early diastole allows characterization of relaxation, whereas compliance assessments and filling pressures are evaluated during late diastole. The evolution of diastolic function differs between adults and children. Unlike in adults, decreased compliance occurs at the same time as delayed relaxation in children. Diastolic function can be evaluated by Doppler echocardiography. The echocardiographic criteria for ventricular relaxation include the E wave, E/A wave ratio, and isovolumic relaxation time. Ventricular compliance can be assessed by the E/e' wave ratio, atrial volume, and Ap wave duration during pulmonary vein flow. In adult intensive-care patients, the E/e' ratio can be used as an index of tolerance for volume expansion in septic patients and to adjust the inotropic support.

CONCLUSION

Clinical studies would allow some of these parameters to be validated for use in children in intensive care.

Comparison of tissue Doppler imaging and conventional echocardiography to discriminate rejection from non-rejection after pediatric heart transplantation

TDI is considered superior to conventional echocardiography for detecting changes in graft function during rejection in adults but has not demonstrated after pediatric OHT. We retrospectively analyzed echocardiograms performed within 24 hours of biopsy in 122 recipients with median age of 8.7 years. Using biopsy findings as the gold standard, we compared paired rejection and non-rejection echocardiograms using each patient as their own control. We included pairs of LV dimensions, FS, volumes, mass, mass/volume, sphericity, wall stress, SSI, SVI, and TDI velocities in this comparison. C-statistic was used to assess discrimination for individual echo variables and combinations of variables. Overall, 647 non-rejection and 24 rejection biopsy-echo pairs were identified. There was a significant decline in TDI velocities and their Z-scores during rejection but not in conventional variables (P ≤ .005). The variable that best discriminated rejection from non-rejection was LV S', with C-statistic = 0.93. Conventional echo variables performed less well with C-statistic range 0.65-0.67 for LV EF, shortening fraction, and mass. TDI is superior to conventional echocardiography measures for discriminating rejection from non-rejection. The use of newer non-invasive parameters to detect myocardial dysfunction and shifting the paradigm of rejection surveillance to detection of non-rejection together provide a promising approach to reducing the need for biopsy in pediatric heart recipients.

Cardiac Abnormalities in Patients With Hutchinson-Gilford Progeria Syndrome

Importance

Hutchinson-Gilford progeria syndrome (HGPS) is an ultrarare disorder associated with premature death due to cardiovascular events during the second decade of life. However, because of its rarity (107 identified living patients), the natural history of cardiac disease remains uncharacterized. Therefore, meaningful cardiac end points for clinical trials have been difficult to establish.

Objective

To examine the course of appearance of cardiac abnormalities in patients with HGPS to identify meaningful cardiac end points for use in future clinical trials.

Design, Setting, and Participants

In this prospective, cross-sectional, observational study, 27 consecutive patients with clinically and genetically confirmed classic HGPS were evaluated at a single center for 1 visit from July 1, 2014, through February 29, 2016, before initiation of treatment.

Exposure

Classic HGPS.

Main Outcomes and Measures

Echocardiography was used to assess ventricular and valve function using standard techniques. Diastolic left ventricular (LV) function was assessed using tissue Doppler imaging. Previously published normative data were used to adjust findings to age and body size.

Results

This study included 27 patients (median age, 5.6 years; age range, 2-17 years; 15 [56%] male). Among echocardiographic indicators, LV diastolic dysfunction, defined as a tissue Doppler septal or lateral early velocity z score less than -2, was the most prevalent abnormality, seen in 16 patients (59%). Diastolic dysfunction was seen in all age groups, and its prevalence increased with age, mirroring findings seen during normal aging. Indicators of LV diastolic function were more abnormal in older patients. The z scores for lateral and septal early velocities were lower (r = -0.77, P < .001; and r = -0.66, P < .001, respectively), whereas those for the ratio of early mitral inflow velocity to early diastolic tissue Doppler myocardial velocity were higher (r = 0.80, P < .001; and r = 0.72, P < .001, respectively) in older patients. Other echocardiographic findings, including LV hypertrophy, LV systolic dysfunction, and valve disease, were less prevalent in the first decade and were seen more frequently in the second decade.

Conclusions and Relevance

In this largest-to-date cohort of patients with HGPS, LV diastolic dysfunction was the most prevalent echocardiographic abnormality and its prevalence increased with aging. Echocardiographic indicators of LV diastolic function may be useful end points in future clinical trials in this patient population.

Serial Changes in Right Ventricular Systolic Function Among Rejection-Free Children and Young Adults After Heart Transplantation

BACKGROUND

Evolution of right ventricular (RV) systolic function after pediatric heart transplantation (HT) has not been well described.

METHODS

We analyzed echocardiograms performed over the first year after HT among children and young adults who remained rejection-free. Ninety-six patients (median age 7.1 [0.1-24.4] years at HT) were included: 22 infants (≤1 year) and 74 noninfants (>1 year). Two-dimensional tricuspid annular plane systolic excursion (TAPSE), tissue Doppler-derived tricuspid annular systolic velocity (S'), fractional area change (FAC), myocardial performance index (MPI), and two-dimensional speckle-tracking-derived RV global longitudinal (GLS) and free wall strain (FWS) were assessed.

RESULTS

All measures of RV function were impaired immediately after HT and significantly improved over the first year: TAPSE z-score (-8.15 ± 1.88 to -3.94 ± 1.65, P < .0001), S' z-score (-4.30 ± 1.36 to -2.28 ± 1.33, P < .0001), FAC (24.37% ± 7.71% to 42.02% ± 7.09%, P < .0001), MPI (0.96 ± 0.47 to 0.41 ± 0.22, P < .0001), GLS (-10.37% ± 3.86% to -21.05% ± 3.41%, P < .0001), and FWS (-11.2% ± 4.08% to -23.66% ± 4.13%, P < .0001). By 1 year post-HT, TAPSE, S', GLS, and FWS, remained abnormal, whereas FAC and MPI nearly normalized. Patients transplanted during infancy demonstrated better recovery of RV systolic function.

CONCLUSIONS

Although RV systolic function improved over the first year after HT in children and young adults without rejection, measures that assess longitudinal contractility remained abnormal at 1 year post-HT. These findings contribute to our understanding of RV myocardial contractility after HT in children and young adults and improve our ability to assess function quantitatively in this population.

Right ventricular function during exercise in children after heart transplantation

Aims

Right ventricular (RV) dysfunction is a common problem after heart transplant (HTx). In this study, we used semi-supine bicycle ergometry (SSBE) stress echocardiography to evaluate RV systolic and diastolic reserve in paediatric HTx recipients.

Methods and results

Thirty-nine pediatric HTx recipients and 23 controls underwent stepwise SSBE stress echocardiography. Colour tissue doppler imaging (TDI) peak systolic (s') and peak diastolic (e') velocities, myocardial acceleration during isovolumic contraction (IVA), and RV free wall longitudinal strain were measured at incremental heart rates (HR). The relationship with increasing HR was evaluated for each parameter by plotting values at each stage of exercise versus HR using linear and non-linear regression models. At rest, HTx recipients had higher HR with lower TDI velocities (s': 5.4 ± 1.7 vs. 10.4 ± 1.8 cm/s, P < 0.001; e': 6.4 ± 2.2 vs.12 ± 2.4 cm/s, P < 0.001) and RV IVA values (IVA: 1.2 ± 0.4 vs. 1.6 ± 0.8 m/s2, P = 0.04), while RV free wall longitudinal strain was similar between groups. At peak exercise, HR was higher in controls and all measurements of RV function were significantly lower in HTx recipients, except for RV free wall longitudinal strain. When assessing the increase in each parameter vs. HR, the slopes were not significantly different between patients and controls except for IVA, which was lower in HTx recipients.

Conclusion

In pediatric HTx recipients RV systolic and diastolic functional response to exercise is preserved with a normal increase in TDI velocities and strain values with increasing HR. The blunted IVA response possibly indicates a mildly decreased RV contractile response but it requires further investigation.

Early assessment of right ventricular systolic function after pediatric heart transplant

RV systolic function is important early after HT; however, it has not been critically assessed in children using quantitative measures. The aim of this study was to describe the most validated and commonly used quantitative echocardiographic measures of RV systolic function early after pediatric HT and to assess associations with qualitative function evaluation and clinical factors. RV systolic function was quantified on the first post-HT echocardiogram >24 hours after cardiopulmonary bypass using two-dimensional TAPSE, Tricuspid annular S', FAC, and MPI. In 145 patients (median age 7.6 years), quantitative RV systolic function was markedly abnormal: mean TAPSE z-score -8.43 ± 1.89; S' z-score -4.36 ± 1.22; FAC 24.4 ± 8.34%; and MPI 0.86 ± 0.51. Few patients had normal quantitative function: TAPSE (0%), S' (1.2%), FAC (9.4%), and MPI (28.4%). In contrast, 48.3% were observed as normal by qualitative assessment. Most clinical factors, including diagnosis, pulmonary vascular resistance, posttransplant hemodynamics, inotropic support, and rejection, were not associated with RV function. In this large pediatric HT population, TAPSE, S', FAC, and MPI were strikingly abnormal early post-HT despite reassuring qualitative assessment and no significant association with clinical factors. This suggests that the accepted normal values of these quantitative measures may not apply in the early post-HT period to accurately grade RV systolic function, and there may be utility in adapting a concept of normal reference values after pediatric HT.

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.

Diffuse Myocardial Fibrosis in Children After Heart Transplantations: A Magnetic Resonance T1 Mapping Study

BACKGROUND

It is unclear whether the myocardium undergoes accelerated fibrotic remodeling in children after heart transplantation (HTx).

METHODS

In this prospective study, cardiac magnetic resonance (CMR) studies in 17 patients 1.3 years (median, range 0.03-12.6 years) after HTx (mean age, 9.8 ± 6.2 years; 8 girls) were compared to CMR studies in 9 healthy controls (mean age, 12.4 ± 2.4 years; 4 girls). T1 measurements were performed at a midventricular short axis slice before (ie, native T1 times) and after the application of 0.2 mmol/kg gadopentetate dimeglumine in the interventricular septum, left ventricular (LV) free wall and encompassing the entire LV myocardium. The tissue-blood partition coefficient (TBPC), reflecting the degree of diffuse myocardial fibrosis, was calculated as a function of the ratio of T1 change of myocardium compared to blood. Native T1 times and TBPC were correlated with echocardiographic parameters of diastolic function.

RESULTS

Native T1 times were significantly higher in HTx patients compared to controls in all regions assessed (LV free wall 973 ± 42 vs 923 ± 12 ms; P < 0.005; interventricular septum 1003 ± 31 vs 974 ± 21 ms, P < 0.05; entire LV myocardium 987 ± 33 vs 951 ± 16 ms; P < 0.005) and correlated with LV E/e' as an echocardiographic marker of diastolic dysfunction (r = 0.54, P < 0.05). The TBPC was elevated in the LV free wall (0.45 ± 0.06 vs 0.40 ± 0.03, P < 0.005) and the entire LV myocardium (0.47 ± 0.06 vs 0.43 ± 0.03, P < 0.05).

CONCLUSIONS

Evidence of diffuse myocardial fibrosis and is already present in children after HTx. It appears to be associated with diastolic dysfunction.

Biomarkers in pediatric heart disease

A biomarker is a characteristic that can be used as an indicator of a biological state. A biomarker can be a clinical observation, laboratory test or an imaging parameter. In this review, we discuss the use of biomarkers in differentiating cardiac from noncardiac disease; predicting the prognosis of patients with heart failure, pulmonary hypertension and dilated cardiomyopathy; diagnosing subclinical cardiac involvement in muscular dystrophy and postchemotherapy cancer patients; detecting acute rejection following heart transplantation; diagnosing Kawasaki disease; aiding the management of postoperative cardiac patients; and managing both common (tetralogy of Fallot) and complex (single-ventricle physiology) congenital heart diseases.

Left ventricular myocardial performance index change for detection of acute cellular rejection in pediatric heart transplantation

EMB, the gold standard for diagnosis of ACR, poses unique risks in children. Limited cross-sectional data have associated LV MPI with ACR. We hypothesize that a relative change in MPI from baseline without ACR to the time of ACR will better detect ACR than an absolute threshold LV MPI value. We identified 40 children with ACR ≥60 days post-transplant matching them by age and time from transplantation to 40 children without ACR. There was a significant increase in LV MPI at time of ACR vs. baseline (0.59 ± 0.17 vs. 0.41 ± 0.11; p < 0.001). There was no difference in LV MPI between baseline and follow-up (0.41 ± 0.11 vs. 0.42 ± 0.11; p = 0.65). An absolute increase in LV MPI of ≥0.47 had 82.5% sensitivity and 85% specificity for ACR, whereas an increase in LV MPI from baseline of ≥20.4% was 90% sensitive and 100% specific. Serial measurement of LV MPI appears to be a sensitive and specific marker of ACR. LV MPI shows good interobserver agreement and increases at the time of EMB-proven ACR with subsequent resolution to baseline measurements upon EMB-proven resolution of ACR. Future studies in larger, prospective cohorts should be undertaken to validate these findings.

Tissue Doppler imaging for rejection surveillance in pediatric heart transplant recipients

BACKGROUND

Most transplant centers perform serial cardiac biopsies for rejection surveillance in pediatric heart transplant (HT) recipients. We sought to assess tissue Doppler imaging (TDI) findings during biopsy specimen-proven rejection in pediatric HT recipients and to develop TDI criteria for absence of rejection with high predictive accuracy.

METHODS

We included the 122 HT recipients in follow-up at our center (median age at HT, 8.7 years). We identified all echocardiograms with adequate TDI data performed within 24 hours of a cardiac biopsy during 2005 to 2011. Rejection was defined as Grade ≥ 2R cellular rejection or antibody-mediated rejection. Paired comparisons of TDI velocities were made using patients' baseline velocities as the control.

RESULTS

Overall, 647 specimen-pairs were identified where there was no rejection at baseline. In 24 of these, the second biopsy specimen demonstrated rejection. Using receiver operating characteristic curve analysis of percentage change from baseline, we identified < 15% decline in left ventricular (LV) S' velocity and < 5% decline in LV A' velocity to individually predict non-rejection with > 99% accuracy. When joint criteria were used, the predictive accuracy was 100%, and no rejection event was misclassified. More than 75% of TDI pairs met these criteria for non-rejection.

CONCLUSIONS

Biopsy specimen-proven rejection is associated with a significant decline in biventricular TDI velocities from baseline in pediatric HT recipients. By using well-defined TDI criteria to predict non-rejection, a substantial proportion of planned biopsies may be deferred or avoided at minimal risk to pediatric HT recipients.

Cardiac Allograft Function During the First Year after Transplantation in Rejection-Free Children and Young Adults

Background—

Allograft dysfunction is a common finding early after heart transplant (HT). We sought to assess the recovery of left (LV) and right ventricular (RV) function during the first year after HT in children and young adults using pulsed-wave tissue Doppler imaging.

Methods and Results—

We analyzed serially performed echocardiography in 44 pediatric HT recipients (median age: 7.3 years at HT) who remained rejection-free during the first year post-transplant. Age-based normative values for systolic ( S ′), early-diastolic ( E ′), and late-diastolic ( A ′) velocities obtained using pulsed-wave tissue Doppler imaging in 380 healthy children were used to transform patient data into z scores. Pulsed-wave tissue Doppler imaging studies ≤10 days post-HT demonstrated biventricular systolic and diastolic dysfunction with most prominent impairment in RV systolic function ( S ′ z score −2.7±0.8), RV early-diastolic filling ( E ′ z score −2.3±1.1), and LV early-diastolic filling ( E ′ z score −2.3±1.1). LV systolic function ( S ′ z score) and late-diastolic filling ( A ′ z score) improved to normal in 11 to 30 days, LV early-diastolic filling ( E ′ z score) in 4 to 6 months, and RV early-diastolic filling in 6 to 9 months ( P <0.001 for all on longitudinal analysis). However, RV systolic function (RV S ′ z score −1.2±1.1) remained impaired 1-year post-transplant. Analysis of serial cardiac catheterization studies showed that RV and LV filling pressures were elevated early post-HT and declined gradually during the first year post-transplant.

Conclusions—

Pediatric HT recipients have biventricular dysfunction using pulsed-wave tissue Doppler imaging early after HT with most significant impairment in RV systolic function and RV and LV early-diastolic filling. Although other aspects of LV and RV function normalize in 6 to 9 months, RV systolic function remains abnormal 1 year-post-transplant.

The gold standard for noninvasive imaging in congenital heart disease: echocardiography

PURPOSE OF REVIEW

Echocardiography in pediatric and congenital heart disease is a key diagnostic technique in patients with congenital heart disease. Due to new technological developments, it has become a rapidly evolving field.

RECENT FINDINGS

In this review, we focus on recent developments in standardization and validation of standard techniques in pediatric and congenital echocardiography. This is mainly related to standardization of image acquisition and normalization of measurements for body size. The rest of the review is focused on the application of three-dimensional echocardiography, tissue Doppler imaging and Speqle tracking techniques to pediatric heart disease.

SUMMARY

New developments in standardization of echocardiography, the introduction of three-dimensional echocardiography and new functional techniques such as tissue Doppler and Speqle tracking strengthen the position of pediatric echocardiography as the most important diagnostic tool for patients with congenital heart disease.