Left ventricular function in children and adults after renal transplantation in childhood

Get to the heart of pediatric kidney transplant recipients: Evaluation of left- and right ventricular mechanics by three-dimensional echocardiography

Background

Kidney transplantation (KTX) markedly improves prognosis in pediatric patients with end-stage kidney failure. Still, these patients have an increased risk of developing cardiovascular disease due to multiple risk factors. Three-dimensional (3D) echocardiography allows detailed assessment of the heart and may unveil distinct functional and morphological changes in this patient population that would be undetectable by conventional methods. Accordingly, our aim was to examine left- (LV) and right ventricular (RV) morphology and mechanics in pediatric KTX patients using 3D echocardiography.

Materials and methods

Pediatric KTX recipients (n = 74) with median age 20 (14–26) years at study enrollment (43% female), were compared to 74 age and gender-matched controls. Detailed patient history was obtained. After conventional echocardiographic protocol, 3D loops were acquired and measured using commercially available software and the ReVISION Method. We measured LV and RV end-diastolic volumes indexed to body surface area (EDVi), ejection fraction (EF), and 3D LV and RV global longitudinal (GLS) and circumferential strains (GCS).

Results

Both LVEDVi (67 ± 17 vs. 61 ± 9 ml/m2; p < 0.01) and RVEDVi (68 ± 18 vs. 61 ± 11 ml/m2; p < 0.01) were significantly higher in KTX patients. LVEF was comparable between the two groups (60 ± 6 vs. 61 ± 4%; p = NS), however, LVGLS was significantly lower (−20.5 ± 3.0 vs. −22.0 ± 1.7%; p < 0.001), while LVGCS did not differ (−29.7 ± 4.3 vs. −28.6 ± 10.0%; p = NS). RVEF (59 ± 6 vs. 61 ± 4%; p < 0.05) and RVGLS (−22.8 ± 3.7 vs. −24.1 ± 3.3%; p < 0.05) were significantly lower, however, RVGCS was comparable between the two groups (−23.7 ± 4.5 vs. −24.8 ± 4.4%; p = NS). In patients requiring dialysis prior to KTX (n = 64, 86%) RVGCS showed correlation with the length of dialysis (r = 0.32, p < 0.05).

Conclusion

Pediatric KTX patients demonstrate changes in both LV and RV morphology and mechanics. Moreover, the length of dialysis correlated with the contraction pattern of the right ventricle.

Cardiac Function in Children After Kidney Transplant

OBJECTIVES

Renal transplant improves echocardiographic markers of systolic and diastolic heart functions. The aim of this study was to evaluate the gradual changes in left and right ventricle functions in children and young adults before and after renal transplant.

MATERIALS AND METHODS

Thirty kidney recipients of median age 13 years (range, 5-19 years) were included the study. Tissue Dopplerimaging from the septal and lateral mitral annulus ofthe left ventricle and free wall of the right ventricle was performed. Right ventricle systolic excursion velocity and tricuspid annular plane systolic excursion were calculated. Systolic and diastolic heart functions-which gained just before transplant, were compared with posttransplant early- term (6 months to 1 year) and long-term (longer than 1 year) functions.

RESULTS

Twelve patients received deceased-donor and 18 patients received living donor renal transplant. Follow-up after transplant was 44 ± 23 months. Left ventricle ejection fractions were normal. The left ventricle, right ventricle, and interventricular septalTei indices were significantly higher before transplant.The posttransplantation early- and late-term results of left ventricle,right ventricle, and interventricular septal Tei indices were similar. Tricuspid annular plane systolic excursion levels were abnormal in 11 patients (36%), and right ventricle systolic excursion velocities were abnormal in 7 patients (23%) before transplant. All tricuspid annular plane systolic excursion levels and 94% ofright ventricle systolic excursion velocities were normal, but left ventricle Tei indices were higher in 8 (26%) and right ventricle Tei indices were higher in 14 patients (46%) at late-term follow-up.

CONCLUSIONS

The systolic and diastolic dysfunctions of both ventricles appear to be highly prevalent in pediatric renal transplant recipients, especially soon after transplant, and were shown to usually decrease with time. Improvements in right ventricle dysfunction are slower, even in optimally treated posttransplant patients.

Echocardiogram screening in pediatric dialysis and transplantation

Transthoracic echocardiography is commonly used to identify structural and functional cardiac abnormalities that can be prevalent in childhood chronic kidney failure (KF). Left ventricular mass (LVM) increase is most frequently reported and may persist post-kidney transplant especially with hypertension and obesity. While systolic dysfunction is infrequently seen in childhood chronic KF, systolic strain identified by speckle tracking echocardiography has been frequently identified in dialysis and it can also persist post-transplant. Echocardiogram association with long-term outcomes has not been studied in childhood KF but there are many adult studies demonstrating associations between increased LVM, systolic dysfunction, strain, diastolic dysfunction, and cardiovascular events and mortality. There has been limited study of interventions to improve echocardiogram status. In childhood, improved blood pressure has been associated with better LVM, and conversion from hemodialysis to hemodiafiltration has been associated with better diastolic and systolic function. Whether long-term cardiac outcomes are also improved with these interventions is unclear. Echocardiography is a well-established technique, and regular use in childhood chronic KF seems justified. A case can be made to extend screening to include speckle tracking echocardiography and intradialytic studies in high-risk populations. Further longitudinal studies including these newer echocardiogram modalities, interventions, and long-term outcomes would help clarify recommendations for optimal use as a screening tool.

Longitudinal Changes in Cardiac Structure and Function in Pediatric Kidney Transplant Recipients

BACKGROUND

Cardiovascular disease results in increased morbidity and mortality in pediatric kidney transplant recipients. Longitudinal changes in cardiac structure and function and the association with blood pressure control over time in pediatric kidney transplant recipients are unknown.

METHODS

To determine the influence of blood pressure control on cardiac changes following pediatric kidney transplant, we conducted a retrospective cohort study of children who received their first kidney transplant at the Hospital for Sick Children from 2004 to 2015. Children were followed until transfer to adult care or censoring in July 2018. Cardiac structure and function parameters were collected from clinical echocardiograms and assessed using standardized scores. Blood pressure control was determined by systolic blood pressure Z scores (above or below the 90th percentile) in combination with antihypertensive medications. A segmented mixed-effects model assessed Z scores of interventricular septum thickness, left ventricular end-diastolic dimension, and left ventricular posterior wall dimension.

RESULTS

Of 142 children included, 58% were men, mean age at transplant was 11 (±4.5) years, and average follow-up time was 4 (±3) years. All cardiac structural Z scores improved during follow-up. Interventricular septum thickness normalized at 4.0 years post-transplant. Left ventricular end-diastolic dimension normalized at 1.5 years post-transplant. Left ventricular posterior wall dimension normalized at 6.3 years post-transplant. Left ventricular mass index showed sustained improvement up to 12 years post-transplant. Individuals with uncontrolled blood pressure had increased left ventricular mass (β=2.97 [95% CI, 0.77-5.16]).

CONCLUSIONS

Cardiac structural abnormalities improve following kidney transplantation and normalize within 7 years, especially with controlled blood pressure. Strict blood pressure control is critical after pediatric kidney transplantation.

Subclinical cardiac dysfunction in pediatric kidney transplant recipients identified by speckle-tracking echocardiography

BACKGROUND

Kidney transplantation (KTx) improves prognosis in children with kidney failure; still, these patients are prone to cardiovascular damage due to multiple risk factors. Our aim was to assess myocardial structure and function in pediatric KTx by conventional and speckle-tracking echocardiography (STE) in association with established cardiovascular risk factors.

METHODS

Forty-two KTx and 39 healthy age- and gender-matched children were evaluated. KTx recipients were further categorized according to the control of hypertension assessed by 24-h ambulatory blood pressure monitoring (ABPM). Subjects underwent pulse wave velocity (PWV) measurement, conventional echocardiography, and 2-dimensional STE. Left and right ventricular (LV, RV) global longitudinal strain (GLS), and LV circumferential strain (GCS) were measured. Glomerular filtration rate (eGFR) was calculated according to the Schwartz formula.

RESULTS

KTx patients had increased blood pressure and arterial stiffness. LV ejection fraction (EF) was preserved along with elevated LV mass index (LVMi) while LVGLS was significantly lower, whereas LVGCS and RVGLS were increased in KTx. Uncontrolled hypertensives had lower LVGLS compared to those with controlled hypertension. Using multiple forward stepwise regression analysis, 24-h SBP and relative wall thickness (RWT) were independent determinants of LVMi, whereas antihypertensive therapy, eGFR, and HOMA-IR were independent determinants of LVGLS.

CONCLUSIONS

Cardiac morphology and function show distinct changes after KTx. Along with comparable ventricular volumes, LV hypertrophy and subclinical myocardial dysfunction are present. Control of hypertension and kidney graft function are major factors of LV performance. STE may be useful to reveal early myocardial dysfunction in pediatric KTx. A higher resolution version of the Graphical abstract is available as Supplementary information.

Comparison of BMI, waist circumference, and waist-to-height ratio for identification of subclinical cardiovascular risk in pediatric kidney transplant recipients

BACKGROUND

Kidney transplant recipients are at high risk for CV morbidity. However, the measure of obesity that best predicts CV risk has not been established.

OBJECTIVE

A prospective, controlled study was conducted to compare the ability of BMI, WC, and WHr to identify CV risk in pediatric kidney transplant recipients.

METHODS

Transplant recipients, aged 3-20 years, had echocardiogram, CIMT, BMI, WC, WHr, blood pressure, lipids, and leptin measured. Receiver operating characteristic analysis was used to compare the ability of BMI, WC, and WHr to detect a composite adverse CV outcome. Presence of the composite outcome was defined by ≥3 of the following five criteria: (a) LVH, (b) high CIMT, (c) impaired myocardial strain, (d) dyslipidemia, and/or (e) hypertension. Multivariate analysis was conducted by generalized estimating equation regression.

RESULTS

We analyzed 108 visits of 42 transplant recipients. Prevalence of obesity by WHr (43.5%) was higher than BMI (24.1%) and WC (12.0%). Proportion of WHr-obese who met criteria for the adverse CV outcome was higher (62.2%) than BMI (34.6%) and WC-obese (33.3%). Leptin levels were higher in children with obesity. Area under the ROC curve for WHr-obese (0.77) was higher compared to BMI (0.47) and WC (0.48) to detect the CV outcome, P = 0.0006. WHr-obesity was associated with 5.72 increased odds of having the adverse CV outcome, P = 0.0001, while BMI and WC were not significant.

CONCLUSION

WHr is more sensitive than BMI or WC to detect subclinical CV risk and should be included in screening of pediatric kidney transplant recipients.

The association of hypertension with asymptomatic cardiovascular organ damage in rheumatoid arthritis

BACKGROUND

The association of hypertension with asymptomatic cardiovascular organ damage in patients with rheumatoid arthritis (RA) has been little studied by echocardiography.

METHODS

Echocardiography was done in 134 RA patients and 102 healthy controls. Left ventricular (LV) geometry was considered abnormal if LV mass index or relative wall thickness was increased. LV diastolic dysfunction was considered present if septal early diastolic tissue velocity <8 cm/s. Systemic arterial compliance (SAC) was assessed from stroke volume index/pulse pressure ratio.

RESULTS

The hypertensive RA patients (n = 72) had higher inflammatory activity, older age and more diabetes than the normotensive RA patients (n = 62) (all p < 0.05). Rates of abnormal LV geometry, LV diastolic dysfunction and lower SAC were higher among the hypertensive RA patients (p < 0.05), but similar between normotensive RA patients and controls. Hypertension was associated with a 3-fold higher prevalence both for abnormal LV geometry (odds ratio 2.89 [95% confidence interval 1.09-7.63], p = 0.03) and for diastolic LV dysfunction (odds ratio 2.92 [95% confidence interval 1.14-7.46], p = 0.03) as well as lower SAC (β = 0.31, p = 0.001) independent of age, gender, diabetes and inflammatory activity measured by erythrocyte sedimentation rate.

CONCLUSION

The presence of asymptomatic cardiovascular organ damage in RA patients is closely associated with hypertension independent of inflammatory activity.

Pretransplant Stable Systolic Cardiac Functions Play an Important Role in Short-term Systolic Cardiac Functions After Kidney Transplant in Children

OBJECTIVES

In this study, our aim was to evaluate the systolic cardiac parameters and related risk factors in children within 6 months after kidney transplant.

MATERIALS AND METHODS

We retrospectively evaluated 24 children who received kidney transplants. Clinical and laboratory parameters before and after transplant were recorded. Results were evaluated statistically, with a P value less than .05 considered significant.

RESULTS

Before transplant, systolic cardiac functions were within normal limits. After transplant, ejection fraction (63.35% ± 5.38% vs 66.95% ± 4.62%; P = .01) was significantly increased and left ventricular mass index (32.63 ± 17.21 g/m2.7 vs 31.29 ± 15.65 g/m2.7; P = .78) was not significantly decreased, whereas fractional shortening (52.16% ± 15.32% vs 59.8% ± 12.94%; P = .54) did not change. Systolic blood pressure, systolic blood pressure index, diastolic blood pressure, and diastolic blood pressure index values were not statistically different before and after transplant (P > .05). The number of antihypertensive agents was significantly decreased (P = .001). Before and after transplant, cardiac geometry was normal in 15 patients (62.5%) and 17 patients (70.8%).

CONCLUSIONS

Our patients, who had stable systolic cardiac function before transplant, showed further improvements in systolic cardiac function even within 6 months after transplant. Therefore, strictly monitored and controlled blood pressure, volume, anemia, and nutrition in children before transplant may play important roles in achieving better cardiac systolic function after kidney transplant.

Reference Ranges of Left Ventricular Strain Measures by Two-Dimensional Speckle-Tracking Echocardiography in Children: A Systematic Review and Meta-Analysis

BACKGROUND

Establishment of the range of reference values and associated variations of two-dimensional speckle-tracking echocardiography (2DSTE)-derived left ventricular (LV) strain is a prerequisite for its routine clinical adoption in pediatrics. The aims of this study were to perform a meta-analysis of normal ranges of LV global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS) measurements derived by 2DSTE in children and to identify confounding factors that may contribute to variance in reported measures.

METHODS

A systematic review was launched in MEDLINE, Embase, Scopus, the Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Library. Search hedges were created to cover the concepts of pediatrics, STE, and left-heart ventricle. Two investigators independently identified and included studies if they reported 2DSTE-derived LV GLS, GCS, or GRS. The weighted mean was estimated by using random effects models with 95% CIs, heterogeneity was assessed using the Cochran Q statistic and the inconsistency index (I(2)), and publication bias was evaluated using the Egger test. Effects of demographic (age), clinical, and vendor variables were assessed in a metaregression.

RESULTS

The search identified 2,325 children from 43 data sets. The reported normal mean values of GLS among the studies varied from -16.7% to -23.6% (mean, -20.2%; 95% CI, -19.5% to -20.8%), GCS varied from -12.9% to -31.4% (mean, -22.3%; 95% CI, -19.9% to -24.6%), and GRS varied from 33.9% to 54.5% (mean, 45.2%; 95% CI, 38.3% to 51.7%). Twenty-six studies reported longitudinal strain only from the apical four-chamber view, with a mean of -20.4% (95% CI, -19.8% to -21.7%). Twenty-three studies reported circumferential strain (mean, -20.3%; 95% CI, -19.4% to -21.2%) and radial strain (mean, 46.7%; 95% CI, 42.3% to 51.1%) from the short-axis view at the midventricular level. A significant apex-to-base segmental longitudinal strain gradient (P < .01) was observed in the LV free wall. There was significant between-study heterogeneity and inconsistency (I(2) > 94% and P < .001 for each strain measure), which was not explained by age, gender, body surface area, blood pressure, heart rate, frame rate, frame rate/heart rate ratio, tissue-tracking methodology, location of reported strain value along the strain curve, ultrasound equipment, or software. The metaregression showed that these effects were not significant determinants of variations among normal ranges of strain values. There was no evidence of publication bias (P = .40).

CONCLUSIONS

This study defines reference values of 2DSTE-derived LV strain in children on the basis of a meta-analysis. In healthy children, mean LV GLS was -20.2% (95% CI, -19.5% to -20.8%), mean GCS was -22.3% (95% CI, -19.9% to -24.6%), and mean GRS was 45.2% (95% CI, 38.3% to 51.7%). LV segmental longitudinal strain has a stable apex-to-base gradient that is preserved throughout maturation. Although variations among different reference ranges in this meta-analysis were not dependent on differences in demographic, clinical, or vendor parameters, age- and vendor-specific referenced ranges were established as well.

Normal ranges of left ventricular strain in children: a meta-analysis

AIMS

The definition of normal values of two-dimensional speckle-tracking echocardiography derived left ventricular (LV) deformation parameters, is of critical importance for the routine application of this modality in children. The objectives of this study were to perform a meta-analysis of normal ranges for longitudinal, circumferential and radial strain/strain rate values and to identify confounders that may contribute to differences in reported measures.

METHODS AND RESULTS

A systematic search was conducted. Studies describing normal healthy subjects and observational studies that used control groups as a comparison were included. Data were combined using a random-effect model. Effects of demographic, clinical and equipment variables were assessed through meta-regression. The search identified 1,192 subjects form 28 articles. Longitudinal strain (LS) normal mean values varied from -12.9 to -26.5 (mean, -20.5; 95% CI, -20.0 to -21.0). Normal mean values of circumferential strain (CS) varied from -10.5 to -27.0 (mean, -22.06; 95% CI, -21.5 to -22.5). Radial strain (RS) normal mean values varied from 24.9 to 62.1 (mean, 45.4; 95% CI, 43.0 to 47.8). Meta-regression showed LV end diastolic diameter as a significant determinant of variation for LS. Longitudinal systolic strain rate (LSRs) was significantly determined by the age and RS by the type of vendor used.

CONCLUSION

Variations among different normal ranges were dependent on the vendor used, LV end-diastolic diameter and age. Vendor-independent software for analyzing myocardial deformation in children, using images from different vendors would be the ideal solution for strain measurements or else using the same system for patient's follow up.

Blood pressure, left ventricular geometry, and systolic function in children exposed to inorganic arsenic

BACKGROUND

Inorganic arsenic (iAs) is a ubiquitous element present in the groundwater worldwide. Cardiovascular effects related to iAs exposure have been studied extensively in adult populations. Few epidemiological studies have been focused on iAs exposure-related cardiovascular disease in children.

OBJECTIVE

In this study we investigated the association between iAs exposure, blood pressure (BP), and functional and anatomical echocardiographic parameters in children.

METHODS

A cross-sectional study of 161 children between 3 and 8 years was conducted in Central Mexico. The total concentration of arsenic (As) species in urine (U-tAs) was determined by hydride generation-cryotrapping-atomic absorption spectrometry and lifetime iAs exposure was estimated by multiplying As concentrations measured in drinking water by the duration of water consumption in years (LAsE). BP was measured by standard protocols, and M-mode echocardiographic parameters were determined by ultrasonography.

RESULTS

U-tAs concentration and LAsE were significantly associated with diastolic (DBP) and systolic blood pressure (SBP) in multivariable linear regression models: DBP and SBP were 0.013 (95% CI: 0.002, 0.024) and 0.021 (95% CI: 0.004, 0.037) mmHg higher in association with each 1-ng/mL increase in U-tAs (p < 0.025), respectively. Left ventricular mass (LVM) was significantly associated with LAsE [5.5 g higher (95% CI: 0.65, 10.26) in children with LAsE > 620 compared with < 382 μg/L-year; p = 0.03] in an adjusted multivariable model. The systolic function parameters left ventricular ejection fraction (EF) and shortening fraction were 3.67% (95% CI: -7.14, -0.20) and 3.41% (95% CI: -6.44, -0.37) lower, respectively, in children with U-tAs > 70 ng/mL compared with < 35 ng/mL.

CONCLUSION

Early-life exposure to iAs was significantly associated with higher BP and LVM and with lower EF in our study population of Mexican children.

Disease activity and left ventricular structure in patients with rheumatoid arthritis

OBJECTIVE

Increased left ventricular (LV) wall thickness/internal diameter ratio (relative wall thickness) was recently reported in RA patients. The aim of this study was to assess the association between LV relative wall thickness and RA disease activity.

METHODS

Clinical and echocardiographic data from 129 RA patients without established cardiovascular disease and 102 controls were used. RA disease activity was assessed by different composite scores and active RA defined by the Simplified Disease Activity Index (SDAI) level exceeding the cut-off for remission (SDAI >3.3).

RESULTS

The RA patients were on average 61.3 years old, 77% were women and 67% had active RA (SDAI >3.3). Patients with active RA had greater LV relative wall thickness and included more patients with treated hypertension (all P < 0.05), but had LV mass index and blood pressure comparable to patients in remission. Having active RA by the SDAI score (β = 0.20, P = 0.008) was also independently associated with greater LV relative wall thickness after adjusting for systolic blood pressure, wall stress, age and sex in a multivariate model. This association was robust also in secondary models including other disease activity composite scores such as the Clinical Disease Activity Index and 28-joint DAS.

CONCLUSION

Among RA patients, higher disease activity was independently associated with greater LV relative wall thickness, reflecting subclinical heart disease. The findings point to the importance of disease activity control in RA patients to prevent progression to clinical heart disease.

Recent developments in kidney transplantation in children

PURPOSE OF REVIEW

Renal transplantation in childhood is a well established procedure with excellent short-term outcomes. However, waiting times for transplantation are still relatively long if living donation cannot be performed, and long-term outcomes after transplantation have not significantly improved during the last decade.

RECENT FINDINGS

This review describes alternative modalities to improve donation rates such as en bloc kidney transplantation from young donors, ABO-incompatible transplantation and kidney paired donation. This review also deals with long-term post-transplant morbidities, such as follows: first, medication side-effects (metabolic syndrome, cardiovascular disease) and with the benefits of steroid and calcineurin inhibitor drug minimization; second, the deleterious impact of viral infections and their management and third, chronic antibody-mediated rejection, its therapeutic and prevention possibilities.

SUMMARY

Donor shortage and long-term morbidities, after transplantation, are still relevant issues in paediatric renal transplantation medicine. Significant research and efforts have been made to advance the field and create novel approaches for improvement of transplantation rates and post-transplant graft or patient survival. These modalities are to be established in the routine setting.

Exercise test in pediatric renal transplant recipients and its relationship with their cardiac function

Pediatric kidney transplant recipients are at increased risk of CVD. Exercise test is a good method to evaluate exercise capacity, cardiorespiratory fitness, and risk of potential CVDs. The aim of this study was to assess the exercise capacity in this population and determine its relationship with their cardiac function using conventional and tissue Doppler echocardiography. Exercise test, conventional and tissue Doppler echocardiography were performed on 44 kidney transplant children (age ranging 11-20, 59% male) with acceptable renal function, and the results were compared with their normal healthy counterparts. Our transplant patients achieved significantly lower maximal heart rate, maximal heart rate ratio, total energy expenditure during the exercise, and maximal O2 consumption (Max VO2 ) than the normal group (p < 0.05). No correlation was found between hemoglobin (Hb) level, dialysis duration, kidney function, and the exercise test parameters. Kidney transplant patients had preserved systolic despite diminished diastolic cardiac function compared to the normal children. Our pediatric renal transplant recipients had severely impaired diastolic dysfunction and significantly reduced MaxVO2 compared with their healthy counterparts. No correlation was found between MaxVO2 and measured indices of systolic and diastolic cardiac function.