Developmental modulation of myocardial mechanics: age- and growth-related alterations in afterload and contractility

The outcome of genetic and non-genetic pediatric cardiomyopathies

BACKGROUND

Pediatric cardiomyopathies (CMP) can be familial or idiopathic with increasing detection of genetic mutations. The study is a retrospective single-center review of cardiomyopathy patients from January 2011 to May 2020. Results of the genetic study, as well as the outcome, were reported. Patients were divided according to the type of CMP, age of presentation, and EF at presentation. Univariate and multivariate analysis and ROC and survival curves were done.

RESULTS

We reported 229 patients under 14 years of age with a diagnosis of cardiomyopathy, most commonly DCM (160 patients (70%)) followed by HCM (26.2%). 52% presented at 6 months of age or less and 119 (52%) required ICU admission at presentation. The genetic and or metabolic disorder was confirmed in 21.4% of patients, most commonly VLCAD defect (16, 7%) and ELAC2 gene defect (10, 4.4%). During the disease course, 88 patients (38.4%) died (48 with DCM, 39 with HCM, and 1 with RCM). An EF of 20% or less at presentation and presentation at 6 months of age or less carries a risk for mortality in patients with DCM and HCM, respectively (RR 3.88 and 2.06 and OR of 11.09 and 4.35, respectively). Death was more common among HCM patients especially patients with positive genetic abnormality compared with patients with DCM.

CONCLUSIONS

The mortality for CMP in children reaches up to 40%, (30% in DCM and 65% in HCM patients). Mortality was higher in those with HCM, DCM with EF of 20% or less, and HCM presented at 6 months of age or less. Whole-exome and/or whole-genome sequencing is advised for all patients of CMP and at-risk family members.

Impact of overweight and obesity in the fetal cardiac function parameters in the second and third trimesters of pregnancy

OBJECTIVE

To assess the impact of overweight and obesity in the second and third trimesters of pregnancy on fetal cardiac function parameters.

METHODS

We performed a prospective cohort study of 374 singleton pregnant women between 20w0d and 36w6d divided into three groups: 154 controls (body mass index - BMI < 25 kg/m2), 140 overweight (BMI 25-30 kg/m2) and 80 obese (BMI ≥ 30 kg/m2). Fetal left ventricular (LV) modified myocardial performance index (Mod-MPI) was calculated according to the following formula: (isovolumetric contraction time + isovolumetric relaxation time)/ejection time. Spectral tissue Doppler was used to determine LV and right ventricular (RV) myocardial performance index (MPI'), peak myocardial velocity during systole (S'), early diastole (E'), and late diastole (A').

RESULTS

We found significant differences between the groups in maternal age (p < 0.001), maternal weight (p < 0.001), BMI (p < 0.001), number of pregnancies (p < 0.001), parity (p < 0.001), gestational age (p = 0.013), and estimated fetal weight (p = 0.003). Overweight pregnant women had higher LV Mod-MPI (0.046 versus 0.044 seconds, p = 0.009) and LV MPI' (0.50 versus 0.47 seconds, p < 0.001) than the control group. Obese pregnant women had higher RV E' than control (6.82 versus 6.33 cm/sec, p = 0.008) and overweight (6.82 versus 6.46 cm/sec, p = 0.047) groups. There were no differences in 5-min APGAR score < 7, neonatal intensive care unit admission, hypoglycemia and hyperglobulinemia between the groups.

CONCLUSIONS

We observed fetal myocardial dysfunction in overweight and obese pregnant women with higher LV Mod-MPI, LV MPI' and RV E' compared to fetuses from normal weight pregnant women.

Time-dependent effects of BRAF-V600E on cell cycling, metabolism, and function in engineered myocardium

Candidate cardiomyocyte (CM) mitogens such as those affecting the extracellular signal-regulated kinase (ERK) signaling pathway represent potential targets for functional heart regeneration. We explored whether activating ERK via a constitutively active mutant of B-raf proto-oncogene (BRAF), BRAF-V600E (caBRAF), can induce proproliferative effects in neonatal rat engineered cardiac tissues (ECTs). Sustained CM-specific caBRAF expression induced chronic ERK activation, substantial tissue growth, deficit in sarcomeres and contractile function, and tissue stiffening, all of which persisted for at least 4 weeks of culture. caBRAF-expressing CMs in ECTs exhibited broad transcriptomic changes, shift to glycolytic metabolism, loss of connexin-43, and a promigratory phenotype. Transient, doxycycline-controlled caBRAF expression revealed that the induction of CM cycling is rapid and precedes functional decline, and the effects are reversible only with short-lived ERK activation. Together, direct activation of the BRAF kinase is sufficient to modulate CM cycling and functional phenotype, offering mechanistic insights into roles of ERK signaling in the context of cardiac development and regeneration.

Endocardial pacing compared to epicardial left ventricle pacing and right ventricle pacing: A single-center long-term experience in a pediatric population

BACKGROUND AND AIMS

Pediatric pacing is usually performed as epicardial pacing in small children in need of pacemaker therapy. Epicardial pacing compared with transvenous pacing for pediatric complete atrioventricular block (CAVB) has different strengths and weaknesses. The epicardial left ventricular wall position of the lead has been considered superior, in terms of contraction pattern, compared to a transvenous right ventricular stimulation. We aimed to compare QRS duration and cardiac function before and after the switch from epicardial to transvenous pacing in a pediatric population.

METHODS

Pediatric patients with congenital or acquired CAVB, who underwent a switch from epicardial-to transvenous pacing at our center from 2005 to 2021, were identified through the national ICD- and Pacemaker Registry. Data regarding clinical status, ECG, and echocardiography before and after the switch and at last follow-up were collected.

RESULTS

We included 15 children. The median age at the switch was 6.7 (4.4-11.7) years with a median weight of 21 (15-39) Kg. The median QRS duration with the transvenous systems was 136 (128-152) ms vs. a QRS duration during epicardial stimulation of 150 (144-170) ms with a median difference in QRS duration of 14 (6-20) ms. Children with a post-surgical AV block had a broader QRS duration, both with epicardial and endocardial stimulation. Before the switch, there was one patient with impaired left ventricular function (LVF) but with normal left ventricular end-diastolic diameters. After the switch, one patient developed symptomatic LV dysfunction with the recovery of LVF at the last follow-up after being implanted with a cardiac resynchronization therapy device.

CONCLUSIONS

Our report of pediatric patients after switching from epicardial to transvenous pacing shows how transvenous pacing is not inferior to epicardial pacing in terms of QRS duration and no significant deterioration of cardiac function was detectable.

Tricuspid valve annular tilt for assessment of pre- and post-intervention right ventricular volume in patients undergoing transcatheter pulmonary valve replacement

INTRODUCTION

Transcatheter pulmonary valve replacement serves as a successful alternative to surgical replacement of a right ventricle to pulmonary artery conduit. Guidelines for recommending transcatheter pulmonary valve replacement depend on MRI right ventricular volumes, which have been correlated to the echocardiographic measure of right ventricular annular tilt. We aim to assess whether right ventricular annular tilt can be a clinically useful alternative tool in the acute and long-term periods after transcatheter pulmonary valve replacement to assess right ventricular health.

METHODS

We reviewed 70 patients who underwent transcatheter pulmonary valve replacement at a single institution. Echocardiographic measurements were obtained prior to transcatheter pulmonary valve replacement, immediately after transcatheter pulmonary valve replacement, and within 6 months to 1 year after transcatheter pulmonary valve replacement. Right ventricular annular tilt measures the angle of the tricuspid valve plane relative to the mitral valve plane at end-diastole in the apical four-chamber view. Right ventricular fractional area change, right ventricular systolic strain, tissue Doppler velocity, and tricuspid annular plane systolic excursion Z-scores were obtained using published methods.

RESULTS

Right ventricular annular tilt decreased significantly immediately after transcatheter pulmonary valve replacement (p = 0.0004), and this reduction in right ventricular volume persisted at the mid-term follow-up (p < 0.0001). Fractional area change did not change significantly after transcatheter pulmonary valve replacement while right ventricular global strain improved at mid-term follow-up despite no significant difference immediately after transcatheter pulmonary valve replacement.

CONCLUSIONS

Right ventricular annular tilt decreases both immediately after transcatheter pulmonary valve replacement and at mid-term follow-up. Right ventricular strain also improved after transcatheter pulmonary valve replacement, corresponding to the improved volume load. Right ventricular annular tilt can be considered as an additional echocardiographic factor to assess right ventricular volume and remodeling after transcatheter pulmonary valve replacement.

Adapting to a new environment: postnatal maturation of the human cardiomyocyte

The postnatal mammalian heart undergoes remarkable developmental changes, which are stimulated by the transition from the intrauterine to extrauterine environment. With birth, increased oxygen levels promote metabolic, structural and biophysical maturation of cardiomyocytes, resulting in mature muscle with increased efficiency, contractility and electrical conduction. In this Topical Review article, we highlight key studies that inform our current understanding of human cardiomyocyte maturation. Collectively, these studies suggest that human atrial and ventricular myocytes evolve quickly within the first year but might not reach a fully mature adult phenotype until nearly the first decade of life. However, it is important to note that fetal, neonatal and paediatric cardiac physiology studies are hindered by a number of limitations, including the scarcity of human tissue, small sample size and a heavy reliance on diseased tissue samples, often without age-matched healthy controls. Future developmental studies are warranted to expand our understanding of normal cardiac physiology/pathophysiology and inform age-appropriate treatment strategies for cardiac disease.

Pediatric Normal Values and Z Score Equations for Left and Right Ventricular Strain by Two-Dimensional Speckle-Tracking Echocardiography Derived from a Large Cohort of Healthy Children

BACKGROUND

Strain values vary with age in children and are both vendor and platform specific. Philips QLAB 10.8 and TomTec AutoSTRAIN are two widely used strain analysis platforms, and both incorporate recent European Association of Cardiovascular Imaging/American Society of Echocardiography/Industry Task Force to Standardize Deformation Imaging guidelines. The aims of this study were to establish normal strain values and Z scores for both platforms using a large data set of healthy children and to compare values among these two platforms and a previous version, QLAB 10.5, which predated the task force guidelines.

METHODS

Echocardiograms from 1,032 subjects <21 years old with structurally and functionally normal hearts were included. Images were obtained on the Philips EPIQ platform. Left ventricular (LV) and right ventricular (RV) strain was analyzed using QLAB 10.8 and AutoSTRAIN, and measurement reliability was assessed. Z score equations were derived as a function of age for QLAB 10.8 (LV longitudinal and circumferential strain) and AutoSTRAIN (LV and RV longitudinal strain). A subset (n = 309) was analyzed using QLAB 10.5. Strain values were compared among the three platforms.

RESULTS

For both of the newer platforms, strain varied with age, with magnitude reaching a maximum at 4 to 5 years. For LV longitudinal strain, the largest differences in value were observed in the youngest patients when using QLAB 10.5; the other two platforms were similar. LV circumferential strain measurements (QLAB 10.5 vs QLAB 10.8) were different for all ages, as were measurements of RV longitudinal strain (QLAB 10.8 vs AutoSTRAIN). Reliability was greater for AutoSTRAIN than for QLAB 10.8 and greater for LV than for RV strain.

CONCLUSIONS

Normal RV and LV strain values and Z scores were generated from a large cohort of children for two commonly used platforms in pediatric echocardiography laboratories. Following the incorporation of task force guidelines, the greatest improvement in standardization was seen in infants. Small differences persist between modern platforms; however, these results support the cautious consideration of comparing interplatform measurements.

Maternal obesity in pregnancy and children’s cardiac function and structure: A systematic review and meta-analysis of evidence from human studies

The prevalence of obesity is increasing worldwide. Experimental animal studies demonstrate that maternal obesity during pregnancy directly affects cardiac structure and function in their offspring, which could contribute to their increased cardiovascular disease (CVD) risk. Currently, a systematic overview of the available evidence regarding maternal obesity and alterations in cardiac structure and function in human offspring is lacking. We systematically searched the electronic databases Embase, MEDLINE and NARCIS from inception to June 29, 2022 including human studies comparing cardiac structure and function from fetal life onwards in offspring of women with and without obesity. The review protocol was registered with PROSPERO International Prospective Register of Systematic Reviews (identifier: CRD42019125071). Risk of bias was assessed using a modified Newcastle-Ottawa scale. Results were expressed using standardized mean differences (SMD). The search yielded 1589 unique publications, of which thirteen articles were included. Compared to offspring of women without obesity, fetuses of women with obesity had lower left ventricular strain, indicative of reduced systolic function, that persisted in infancy (SMD -2.4, 95% confidence interval (CI) -4.4 standard deviation (SD) to -0.4 SD during fetal life and SMD -1.0, 95% CI -1.6 SD to -0.3 SD in infancy). Furthermore, infants born to women with obesity had a thicker interventricular septum (SMD 0.6 SD, 95% CI 0.0 to 1.2 SD) than children born to women without obesity. In conclusion, cardiac structure and function differs between fetuses and children of women with and without obesity. Some of these differences were present in fetal life, persisted in childhood and are consistent with increased CVD risk. Long-term follow-up research is warranted, as studies in offspring of older age are lacking.

Reference centiles for left ventricular longitudinal global and regional systolic strain by automated functional imaging in healthy Egyptian children

BACKGROUND

Two-dimensional speckle tracking echocardiography-derived left ventricular longitudinal systolic strain is an important myocardial deformation parameter for assessing the systolic function of the left ventricle. Strain values differ according to the vendor machine and software. This study aimed to provide normal reference values for global and regional left ventricular longitudinal systolic strain in Egyptian children using automated functional imaging software integrated into the General Electric healthcare machine and to study the correlation between the global longitudinal left ventricular systolic strain and age, body size, vital data, and some echocardiographic parameters.

METHODS

Healthy children (250) aged from 1 to 16 years were included. Conventional echocardiography was done to measure the left ventricular dimensions and function. Automated functional imaging was performed to measure the global and regional peak longitudinal systolic strain.

RESULTS

The global longitudinal strain was -21.224 ± 1.862%. The regional strain was -20.68 ± 2.11%, -21.06 ± 1.84%, and -21.86 ± 2.71% at the basal, mid, and apical segments, respectively. The mean values of the systolic longitudinal strain become significantly more negative from base to apex. Age differences were found as regard to global and regional longitudinal strain parameters but no gender differences. The global peak longitudinal systolic strain correlated positively with age. No correlations were found with either the anthropometric parameters or the vital data.

CONCLUSIONS

Age-specific normal values for two-dimensional speckle tracking-derived left ventricular longitudinal regional and global systolic strain are established using automated functional imaging.

Normal Left Ventricular Systolic and Diastolic Strain Rate Values in Children Derived from Two-Dimensional Speckle-Tracking Echocardiography

BACKGROUND

Strain rate (SR) parameters derived from two-dimensional speckle-tracking echocardiography have prognostic value in children with heart disease. Routine use is hindered by a lack of normative data. The aim of this study was to determine reference values and Z scores for left ventricular systolic and diastolic SR in a large cohort of healthy children.

METHODS

Echocardiograms from 577 subjects ≤18 years of age (mean age, 9.6 ± 5.6 years; range, 1 day to 18.0 years; 46% female) with structurally and functionally normal hearts were retrospectively included. Left ventricular longitudinal and circumferential systolic and early and late diastolic SR were measured using two-dimensional speckle-tracking echocardiography from the apical four-chamber and short-axis mid-papillary views. Associations with age and body surface area were assessed using Spearman correlation and generalized additive modeling. The relationship between systolic SR and wall stress (afterload) was examined. Analyses were conducted with and without correction for heart rate. Multivariable linear regression modeling was used to identify independent factors associated with the SR parameters. Z score equations were derived from a selected best-fit parametric model.

RESULTS

All SR parameters differed significantly by age group. The magnitude of all SR values decreased with increasing age and body surface area. Systolic SR magnitude was inversely related to wall stress in children ≤7 years of age but not did not vary significantly in the older age groups. All relationships were maintained after heart rate correction. SR measurements had very good or excellent agreement.

CONCLUSION

Longitudinal and circumferential systolic and diastolic SR parameters are presented from a large cohort of healthy children using two-dimensional speckle-tracking echocardiography from the Philips platform. SR values differ significantly by age and body surface area. These results suggest that the myocardium becomes less sensitive to afterload with maturity. Z score equations based on age are presented, which should promote further clinical and research use.

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.

Neuromuscular-blocking agents for tracheal intubation in pediatric patients (0-12 years): A systematic review and meta-analysis

BACKGROUND

The benefit of using neuromuscular-blocking agents to facilitate tracheal intubation in pediatric patients remains unclear due to variations in design, treatments, and results among trials. By combining the available evidence, we aimed to establish whether scientific findings are consistent and can be generalized across various populations, settings, and treatments.

METHODS

A systematic search for randomized controlled trials, related to the use of neuromuscular-blocking agents for tracheal intubation in American Society of Anesthesiologists class I-II participants (0-12 years), was performed. We considered all randomized controlled trials that studied whether intubation conditions and hemodynamics obtained by using neuromuscular-blocking agents were equivalent to those that were achieved without neuromuscular-blocking agents. We combined the outcomes in Review Manager 5.3 (RevMan, The Cochrane Collaboration) by pairwise random-effects meta-analysis using a risk ratio (RR) for intubation conditions and mean difference for hemodynamic values (mean [95% Confidence Intervals]). Heterogeneity among trials was explored using sensitivity analyses.

RESULTS

We identified 22 eligible randomized controlled trials with 1651 participants. Overall, the use of a neuromuscular-blocking agent was associated with a clinically important increase in the likelihood of both excellent (RR = 1.41 [1.19-1.68], I²  = 76%) and acceptable (RR = 1.13 [1.07-1.19], I²  = 68%) intubating conditions. There is strong evidence that both unacceptable intubation conditions (RR = 0.35 [0.22-0.46], I²  = 23%) and failed first intubation attempts (RR = 0.25 [0.14-0.42], I²  = 0%) were less likely to occur when a neuromuscular-blocking agent was used compared with when it was not. Higher systolic or mean arterial pressures (mean difference = 13.3 [9.1-17.5] mm Hg, I²  = 69%) and heart rates (mean difference = 15.9 [11.0-20.8] beats/min, I²  = 75%) as well as a lower incidence of arrhythmias were observed when tracheal intubation was facilitated by neuromuscular-blocking agents.

CONCLUSION

The use of a neuromuscular-blocking agent during light-to-moderate depth of anesthesia can improve the quality as well as the success rate of tracheal intubation and is associated with better hemodynamic stability during induction of anesthesia.

Intrauterine exposure to chronic hypoxia in the rat leads to progressive diastolic function and increased aortic stiffness from early postnatal developmental stages

AIM

We sought to explore whether fetal hypoxia exposure, an insult of placental insufficiency, is associated with left ventricular dysfunction and increased aortic stiffness at early postnatal ages.

METHODS

Pregnant Sprague Dawley rats were exposed to hypoxic conditions (11.5% FiO2 ) from embryonic day E15-21 or normoxic conditions (controls). After delivery, left ventricular function and aortic pulse wave velocity (measure of aortic stiffness) were assessed longitudinally by echocardiography from day 1 through week 8. A mixed ANOVA with repeated measures was performed to compare findings between groups across time. Myocardial hematoxylin and eosin and picro-sirius staining were performed to evaluate myocyte nuclear shape and collagen fiber characteristics, respectively.

RESULTS

Systolic function parameters transiently increased following hypoxia exposure primarily at week 2 (p < .008). In contrast, diastolic dysfunction progressed following fetal hypoxia exposure beginning weeks 1-2 with lower early inflow Doppler velocities, and less of an increase in early to late inflow velocity ratios and annular and septal E'/A' tissue velocities compared to controls (p < .008). As further evidence of altered diastolic function, isovolumetric relaxation time was significantly shorter relative to the cardiac cycle following hypoxia exposure from week 1 onward (p < .008). Aortic stiffness was greater following hypoxia from day 1 through week 8 (p < .008, except week 4). Hypoxia exposure was also associated with altered nuclear shape at week 2 and increased collagen fiber thickness at week 4.

CONCLUSION

Chronic fetal hypoxia is associated with progressive LV diastolic dysfunction, which corresponds with changes in nuclear shape and collagen fiber thickness, and increased aortic stiffness from early postnatal stages.

Is Doppler echocardiography useful for estimating left ventricular filling pressures in pediatric heart transplant recipients?

LV E/E' ratio obtained using Doppler echocardiography is considered a surrogate for LV filling pressure in adults but has performed poorly in children. We hypothesized that LV E/E' ratio Z-score, adjusted for age, will relate more strongly to LV filling pressures than LV E/E' ratio in pediatric HT recipients. We analyzed 751 echocardiograms performed within 24 hours of a heart catheterization in 122 pediatric HT recipients (median age at HT 13 years, median 6 studies per patient). The primary end-point was PCWP, assessed both as a continuous and a binary variable. Associations with LV E/E' ratios and z-scores were assessed using generalized estimating equations models. PCWP, LV E/E' ratios (using E' from LV free wall, septum, and their average), and LV E/E' ratio Z-scores, all declined over time after HT. LV E/E' ratios and their Z-scores were significantly associated with PCWP assessed as a continuous variable (P < 0.001 for all); however, the relationship was weak (R² range, 0.083 to 0.121). LV E/E' ratios and their Z-scores were also significantly associated with PCWP as a binary variable (P < 0.001 for all) but with only modest ability to discriminate PCWP ≥15 mm Hg (c-statistic range, 0.660 to 0.695). The association between LV E/E' ratio and PCWP in pediatric HT recipients is modest. Using a LV E/E' ratio Z-score did not result in significantly improved association with PCWP. Current Doppler echocardiographic methods are unreliable for estimating LV filling pressures in pediatric HT recipients.

Effects of dexrazoxane on doxorubicin-related cardiotoxicity and second malignant neoplasms in children with osteosarcoma: a report from the Children's Oncology Group

Background

Dexrazoxane protects from lower-cumulative-dose doxorubicin cardiotoxicity, but the effect of dexrazoxane in children with sarcoma treated with higher-cumulative-dose doxorubicin is unknown.

Methods

We evaluated children with osteosarcoma (OS) on two Children's Oncology Group trials with higher dose doxorubicin (375-600 mg/m²) preceded by dexrazoxane (10:1 dexrazoxane:doxorubicin dosing). They were evaluated after the minimum expected treatment time (METT), defined as 28 weeks. Cardiotoxicity was identified by echocardiography and serum N-terminal pro-brain natriuretic peptide (NT-proBNP). Second malignant neoplasm (SMN) data was collected.

Results

All children had normal left ventricular (LV) systolic function as measured by LV fractional shortening and no heart failure. The end-diastolic septal thickness Z-scores (P < 0.01) and LV mass Z-scores (P < 0.01) were significantly smaller than normal for body-surface area in both sexes. The average LV mass Z-scores were significantly smaller for girls (P < 0.01) and marginally smaller for boys (P = 0.06). Girls had significantly smaller LV end-diastolic dimension Z-scores normalized to BSA (P < 0.01) compared to healthy controls and had significant increases in NT-proBNP. Four children developed SMNs as first events, a rate similar to historical controls.

Conclusions

Dexrazoxane prevented LV dysfunction and heart failure in children with OS receiving higher dose doxorubicin. However, LV structural changes were not fully prevented, especially in girls. As a result, hearts become abnormally small for body size, resulting in higher LV stress. Dexrazoxane did not increase the risk of SMN. Dexrazoxane should be used in this population, particularly for girls, to mitigate anthracycline-induced cardiotoxicity.

Trial registrations

ClinicalTrials.gov: NCT00003937 (P9754) registered 1 Nov 1999, and NCT00023998 (AOST0121) registered 13 Sept 2001.

Long-Term Outcomes of Childhood Left Ventricular Noncompaction Cardiomyopathy: Results From a National Population-Based Study

BACKGROUND

Long-term outcomes for childhood left ventricular noncompaction (LVNC) are uncertain. We examined late outcomes for children with LVNC enrolled in a national population-based study.

METHODS

The National Australian Childhood Cardiomyopathy Study includes all children in Australia with primary cardiomyopathy diagnosed before 10 years of age between 1987 and 1996. Outcomes for subjects with LVNC with a dilated phenotype (LVNC-D) were compared with outcomes for those with dilated cardiomyopathy. Propensity-score analysis was used for risk factor adjustment.

RESULTS

There were 29 subjects with LVNC (9.2% of all cardiomyopathy subjects), with a mean annual incidence of newly diagnosed cases of 0.11 per 100 000 at-risk individuals. Congestive heart failure was the initial symptom in 24 of 29 subjects (83%), and 27 (93%) had LVNC-D. The median age at diagnosis was 0.3 (interquartile interval, 0.08-1.3) years. The median duration of follow-up was 6.8 (interquartile interval, 0.7-24.0) years for all subjects and 24.7 (interquartile interval, 23.3 - 27.7) years for surviving subjects. Freedom from death or transplantation was 48% (95% confidence interval [CI], 30-65) at 10 years after diagnosis and 45% (95% CI, 27-63) at 15 years. In competing-risk analysis, 21% of subjects with LVNC were alive with normal left ventricular systolic function, and 31% were alive with abnormal function at 15 years. Propensity-score matching between subjects with LVNC-D and those with dilated cardiomyopathy suggested a lower freedom from death/transplantation at 15 years after diagnosis in the subjects with LVNC-D (LVNC-D, 46% [95% CI, 26-66] versus dilated cardiomyopathy, 70% [95% CI, 42-97]; P=0.08). Using propensity-score inverse probability of treatment-weighted Cox regression, we found evidence that LVNC-D was associated with a greater risk of death or transplantation (hazard ratio, 2.3; 95% CI, 1.4-3.8; P=0.0012).

CONCLUSIONS

Symptomatic children with LVNC usually present in early infancy with a predominant dilated phenotype. Long-term outcomes are worse than for matched children with dilated cardiomyopathy.

A magnetics-based approach for fine-tuning afterload in engineered heart tissues

Afterload plays important roles during heart development and disease progression, however, studying these effects in a laboratory setting is challenging. Current techniques lack the ability to precisely and reversibly alter afterload over time. Here, we describe a magnetics-based approach for achieving this control and present results from experiments in which this device was employed to sequentially increase afterload applied to rat engineered heart tissues (rEHTs) over a 7-day period. The contractile properties of rEHTs grown on control posts marginally increased over the observation period. The average post deflection, fractional shortening, and twitch velocities measured for afterload-affected tissues initially followed this same trend, but fell below control tissue values at high magnitudes of afterload. However, the average force, force production rate, and force relaxation rate for these rEHTs were consistently up to 3-fold higher than in control tissues. Transcript levels of hypertrophic or fibrotic markers and cell size remained unaffected by afterload, suggesting that the increased force output was not accompanied by pathological remodeling. Accordingly, the increased force output was fully reversed to control levels during a stepwise decrease in afterload over 4 hours. Afterload application did not affect systolic or diastolic tissue lengths, indicating that the afterload system was likely not a source of changes in preload strain. In summary, the afterload system developed herein is capable of fine-tuning EHT afterload while simultaneously allowing optical force measurements. Using this system, we found that small daily alterations in afterload can enhance the contractile properties of rEHTs, while larger increases can have temporary undesirable effects. Overall, these findings demonstrate the significant role that afterload plays in cardiac force regulation. Future studies with this system may allow for novel insights into the mechanisms that underlie afterload-induced adaptations in cardiac force development.

Right Ventricular Dissipative Energy Loss Detected by Vector Flow Mapping in Children: Characteristics of Normal Values

OBJECTIVES

The feasible application of vector flow mapping (VFM)-derived right ventricular (RV) energy loss (EL) is lacking. This study was designed to determine reference values of VFM-derived EL within the right ventricle and evaluate potential correlated variables.

METHODS

A total of 90 healthy children were enrolled. Velocity vector fields of the intra-RV outflow tract and pulmonary trunk (OP) and RV blood flow were obtained from the parasternal short-axis view and RV focused apical 4-chamber view, respectively. RV-EL and OP-EL values during diastole and systole were calculated using VFM analysis. The potential relationships between demographic and echocardiographic parameters and the dissipative EL were also identified.

RESULTS

Mean subject age was 8.99 ± 5.35 years. The median (interquartile range) values were 8.82 (5.47-14.30) W/m for RV diastolic EL, 3.17 (2.11-5.54) W/m for RV systolic EL, 18.82 (13.93-24.92) W/m for OP diastolic EL, and 29.88 (20.62-40.78) W/m for OP systolic EL, respectively. The dissipative EL values were negatively correlated with age and RV global strain, and positively correlated with heart rate and RV Tei index. Multivariate analysis showed that age was the primary independent predictor of these 4 types of EL, while heart rate and strain were contributors of the RV diastolic EL and OP systolic EL.

CONCLUSIONS

The present study initially validated the application of vector flow mapping-derived EL analysis in right ventricle and established reference values for the future assessment of children with cardiopulmonary disease. Age, heart rate, and strain were independent variables correlated with the dissipative EL.

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.

Long-term contractile activity and thyroid hormone supplementation produce engineered rat myocardium with adult-like structure and function

The field of cardiac tissue engineering has developed rapidly, but structural and functional immaturity of engineered heart tissues hinder their widespread use. Here, we show that a combination of low-rate (0.2 Hz) contractile activity and thyroid hormone (T3) supplementation significantly promote structural and functional maturation of engineered rat cardiac tissues ("cardiobundles"). The progressive maturation of cardiobundles during first 2 weeks of culture resulted in cell cycle exit and loss of spontaneous activity, which in longer culture yielded decreased contractile function. Maintaining a low level of contractile activity by 0.2 Hz pacing between culture weeks 3 and 5, combined with T3 treatment, yielded significant growth of cardiobundle and myocyte cross-sectional areas (by 68% and 32%, respectively), increased nuclei numbers (by 22%), improved twitch force (by 39%), shortened action potential duration (by 32%), polarized N-cadherin distribution, and switch from immature (slow skeletal) to mature (fast) cardiac troponin I isoform expression. Along with advanced functional output (conduction velocity 53.7 ± 0.8 cm/s, specific force 70.1 ± 5.8 mN/mm²), quantitative ultrastructural analyses revealed similar metrics and abundance of sarcomeres, T-tubules, M-bands, and intercalated disks compared to native age-matched (5-week) and adult (3-month) ventricular myocytes. Unlike 0.2 Hz regime, chronic 1 Hz pacing resulted in significant cardiomyocyte loss and formation of necrotic core despite the use of dynamic culture. Overall, our results demonstrate remarkable ultrastructural and functional maturation of neonatal rat cardiomyocytes in 3D culture and reveal importance of combined biophysical and hormonal inputs for in vitro engineering of adult-like myocardium.

STATEMENT OF SIGNIFICANCE

Compared to human stem cell-derived cardiomyocytes, neonatal rat ventricular myocytes show advanced maturation state which makes them suitable for in vitro studies of postnatal cardiac development. Still, maturation process from a neonatal to an adult cardiomyocyte has not been recapitulated in rodent cell cultures. Here, we show that low-frequency pacing and thyroid hormone supplementation of 3D engineered neonatal rat cardiac tissues synergistically yield significant increase in cell and tissue volume, robust formation of T-tubules and M-lines, improved sarcomere organization, and faster and more forceful contractions. To the best of our knowledge, 5-week old engineered cardiac tissues described in this study are the first that exhibit both ultrastructural and functional characteristics approaching or matching those of adult ventricular myocardium.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

Long-Term Outcomes of Hypertrophic Cardiomyopathy Diagnosed During Childhood: Results From a National Population-Based Study

BACKGROUND

Late survival and symptomatic status of children with hypertrophic cardiomyopathy have not been well defined. We examined long-term outcomes for pediatric hypertrophic cardiomyopathy.

METHODS

The National Australian Childhood Cardiomyopathy Study is a longitudinal population-based cohort study of children (0-10 years of age) diagnosed with cardiomyopathy between 1987 and 1996. The primary study end point was time to death or cardiac transplantation.

RESULTS

There were 80 patients with hypertrophic cardiomyopathy, with a median age at diagnosis of 0.48 (interquartile range, 0.1, 2.5) years. Freedom from death/transplantation was 86% (95% confidence interval [CI], 77.0-92.0) 1 year after presentation, 80% (95% CI, 69.0-87.0) at 10 years, and 78% (95% CI, 67.0-86.0) at 20 years. From multivariable analyses, risk factors for death/transplantation included symmetrical left ventricular hypertrophy at the time of diagnosis (hazard ratio, 4.20; 95% CI, 1.60-11.05; P=0.004), Noonan syndrome (hazard ratio, 2.88; 95% CI, 1.02-8.08; P=0.045), higher posterior wall thickness z score (hazard ratio, 1.45; 95% CI, 1.22-1.73; P<0.001), and lower fractional shortening z score (hazard ratio, 0.84; 95% CI, 0.74-0.95; P=0.005) during follow-up. Nineteen (23%) subjects underwent left ventricular myectomy. At a median of 15.7 years of follow-up, 27 (42%) of 63 survivors were treated with β-blocker, and 13 (21%) had an implantable cardioverter-defibrillator.

CONCLUSIONS

The highest risk of death or transplantation for children with hypertrophic cardiomyopathy is within 1 year after diagnosis, with low attrition rates thereafter. Many subjects receive medical, surgical, or device therapy.

No Obesity Paradox in Pediatric Patients With Dilated Cardiomyopathy

OBJECTIVES

This study aimed to examine the role of nutrition in pediatric dilated cardiomyopathy (DCM).

BACKGROUND

In adults with DCM, malnutrition is associated with mortality, whereas obesity is associated with survival.

METHODS

The National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry was used to identify patients with DCM and categorized by anthropometric measurements: malnourished (MN) (body mass index [BMI] <5% for age ≥2 years or weight-for-length <5% for <2 years), obesity (BMI >95% for age ≥2 years or weight-for-length >95% for <2 years), or normal bodyweight (NB). Of 904 patients with DCM, 23.7% (n = 214) were MN, 13.3% (n=120) were obese, and 63.1% (n=570) were NB.

RESULTS

Obese patients were older (9.0 vs. 5.7 years for NB; p < 0.001) and more likely to have a family history of DCM (36.1% vs. 23.5% for NB; p = 0.023). MN patients were younger (2.7 years vs. 5.7 years for NB; p < 0.001) and more likely to have heart failure (79.9% vs. 69.7% for NB; p = 0.012), cardiac dimension z-scores >2, and higher ventricular mass compared with NB. In multivariable analysis, MN was associated with increased risk of death (hazard ratio [HR]: 2.06; 95% confidence interval [CI]: 1.66 to 3.65; p < 0.001); whereas obesity was not (HR: 1.49; 95% CI: 0.72 to 3.08). Competing outcomes analysis demonstrated increased risk of mortality for MN compared with NB (p = 0.03), but no difference in transplant rate (p = 0.159).

CONCLUSIONS

Malnutrition is associated with increased mortality and other unfavorable echocardiographic and clinical outcomes compared with those of NB. The same effect of obesity on survival was not observed. Further studies are needed investigating the long-term impact of abnormal anthropometric measurements on outcomes in pediatric DCM. (Pediatric Cardiomyopathy Registry; NCT00005391).

Echocardiographic Evaluation of Ventricular Function-For the Neonatologist and Pediatric Intensivist

In the neonatal and pediatric intensive care setting, bedside cardiac ultrasound is often used to assess ventricular dimensions and function. Depending upon the underlying disease process, it is necessary to be able to evaluate the systolic and diastolic function of left and or right ventricles. The systolic function of left ventricle is mostly assessed qualitatively on visual inspection "eye-balling" and quantitatively by measuring circumferential fraction shortening or calculating the ejection fraction by Simpson's planimetry. The assessment of left ventricular diastolic function relies essentially on the mitral valve and pulmonary venous Doppler tracings or tissue Doppler evaluation. The right ventricular particular shape and anatomical position does not permit to use the same parameters for measuring systolic function as is used for the LV. Tricuspid annular plane systolic excursion (TAPSE) and S' velocity on tissue Doppler imaging are more often used for quantitative assessment of right ventricle systolic function. Several parameters proposed to assess right ventricle systolic function such as fractional area change, 3D echocardiography, speckle tracking, and strain rate are being researched and normal values for children are being established. Diastolic function of right ventricle is evaluated by tricuspid valve and hepatic venous Doppler tracings or on tissue Doppler evaluation. The normal values for children are pretty similar to adults while normal values for the neonates, especially preterm infants, may differ significantly from adult population. The normal values for most of the parameters used to assess cardiac function in term neonates and children have now been established.

Differences in Presentation and Outcomes Between Children With Familial Dilated Cardiomyopathy and Children With Idiopathic Dilated Cardiomyopathy: A Report From the Pediatric Cardiomyopathy Registry Study Group

BACKGROUND

Research comparing the survival of children with familial dilated cardiomyopathy (FDCM) to that of children with idiopathic dilated cardiomyopathy (IDCM) has produced conflicting results.

METHODS AND RESULTS

We analyzed data from children with FDCM or IDCM using the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry. Compared to children with IDCM (n=647), children with FDCM (n=223) were older (mean 6.2 versus 4.5 years, P<0.001), less often had heart failure (64% versus 78%, P<0.001), had less-depressed mean left ventricular fractional shortening z scores (-7.85±3.98 versus -9.06±3.89, P<0.001) and lower end-diastolic dimension z scores (4.12±2.61 versus 4.91±2.57, P<0.001) at diagnosis. The cumulative incidence of death was lower for patients with FDCM compared with IDCM (P=0.04; hazard ratio 0.64, P=0.06), but no difference in risk of transplant or the combined death or transplant outcome. There was no difference in the proportion of children with echocardiographic normalization at 3 years of follow-up (FDCM, 30% versus IDCM, 26%; P=0.33). Multivariable analysis showed no difference in outcomes between FDCM and IDCM but for both groups older age, congestive heart failure, and increased left ventricular end-systolic dimension zscore at diagnosis were independently associated with an increased risk of death or heart transplantation (all Ps<0.001).

CONCLUSIONS

There was no survival difference between FDCM and IDCM after adjustment for other factors. Older age, congestive heart failure, and greater left ventricular dilation at diagnosis were independently associated with increased risk of the combined end point of death or transplantation.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifier: NCT00005391.

A Doppler Echocardiographic Study of the Myocardial Inotropic Response to Peak Semisupine Exercise in Healthy Children: Development of a Simplified Index of Myocardial Reserve

BACKGROUND

Stress echocardiography has been advocated for the detection of abnormal myocardial function and unmasking diminished myocardial reserve in pediatric patients. The aim of this study was to create a simplified index of myocardial reserve, derived from the myocardial inotropic response to peak semisupine exercise in healthy children, and illustrate its applicability in a sample of pediatric oncology patients.

METHODS

In this prospective analysis, children (7-18 years of age) with normal cardiac structure and function performed semisupine stress echocardiography to volitional fatigue. The quotient of wall stress at peak systole and heart rate-corrected velocity of circumferential fiber shortening were calculated at baseline and at peak exercise, the difference of which was termed the index of myocardial reserve (IMR). The IMR was also calculated in a retrospective sample of pediatric oncology patients with normal resting left ventricular function who had received anthracycline treatment and had performed the same exercise protocol to illustrate utility.

RESULTS

Fifty healthy subjects (mean age, 13.2 ± 2.6 years) and 33 oncology patients (mean age, 12.7 ± 4.0 years) were assessed. In the healthy children at peak exercise, heart rate-corrected velocity of circumferential fiber shortening significantly increased (from 1.17 ± 0.17 to 1.58 ± 0.24 circ · sec^-1, P < .001), while the quotient of wall stress at peak systole significantly decreased (from 75.3 ± 17.1 to 55.3 ± 13.8 g · cm^-2, P < .001), shifting the plot of the relationship between the two parameters upward and to the left. The mean IMR was -30.8 ± 17.8, and the normal distribution ranged from -4.7 (fifth percentile) to -67.3 (95th percentile). The IMR was abnormal in 10 oncology patients who were treated with anthracyclines.

CONCLUSIONS

The authors have developed a novel IMR. Relative to the normal distribution of this IMR in healthy subjects, it is possible to identify patients with abnormal myocardial reserve. Thus, this study demonstrates the application of the IMR to aid in clinical decision making in individual patients.

Effects of Streptococcus sanguinis Bacteriocin on Deformation, Adhesion Ability, and Young's Modulus of Candida albicans

In order to study the thallus changes on microscopic morphology and mechanical properties of Candida albicans antagonized by Streptococcus sanguinis bacteriocin, the adhesion ability and Young's modulus of thalli and hypha of Candida albicans were measured by the relative measurement method using atomic force microscope's (AFM) tapping model. The results showed that the average adhesion ability and Young's modulus of thalli were 7.35 ± 0.77 nN and 7.33 ± 1.29 Mpa, respectively; the average adhesion ability and Young's modulus of hypha were 9.82 ± 0.39 nN and 4.04 ± 0.76 Mpa, respectively. After being antagonized by Streptococcus sanguinis bacteriocin, the adhesion ability was decreased along with the increasing of deformation in reaction region and Young's modulus followed the same changes. It could be concluded that the adhesion ability of hypha was greater than thalli, Young's modulus of hypha was less than thalli, and adhesion ability and Young's modulus of Candida albicans were decreased significantly after being antagonized by Streptococcus sanguinis bacteriocin.

Maturational Patterns of Systolic Ventricular Deformation Mechanics by Two-Dimensional Speckle-Tracking Echocardiography in Preterm Infants over the First Year of Age

BACKGROUND

The aim of this study was to determine the maturational changes in systolic ventricular strain mechanics by two-dimensional speckle-tracking echocardiography in extremely preterm neonates from birth to 1 year of age and discern the impact of common cardiopulmonary abnormalities on the deformation measures.

METHODS

In a prospective multicenter study of 239 extremely preterm infants (<29 weeks gestation at birth), left ventricular (LV) global longitudinal strain (GLS) and global longitudinal systolic strain rate (GLSRs), interventricular septal wall (IVS) GLS and GLSRs, right ventricular (RV) free wall longitudinal strain and strain rate, and segmental longitudinal strain in the RV free wall, LV free wall, and IVS were serially measured on days 1, 2, and 5 to 7, at 32 and 36 weeks postmenstrual age, and at 1 year corrected age (CA). Premature infants who developed bronchopulmonary dysplasia or had echocardiographic findings of pulmonary hypertension were analyzed separately.

RESULTS

In uncomplicated preterm infants (n = 103 [48%]), LV GLS and GLSRs remained unchanged from days 5 to 7 to 1 year CA (P = .60 and P = .59). RV free wall longitudinal strain, RV free wall longitudinal strain rate, and IVS GLS and GLSRs significantly increased over the same time period (P < .01 for all measures). A significant base-to-apex (highest to lowest) segmental longitudinal strain gradient (P < .01) was seen in the RV free wall and a reverse apex-to-base gradient (P < .01) in the LV free wall. In infants with bronchopulmonary dysplasia and/or pulmonary hypertension (n = 119 [51%]), RV free wall longitudinal strain and IVS GLS were significantly lower (P < .01), LV GLS and GLSRs were similar (P = .56), and IVS segmental longitudinal strain persisted as an RV-dominant base-to-apex gradient from 32 weeks postmenstrual age to 1 year CA.

CONCLUSIONS

This study tracks the maturational patterns of global and regional deformation by two-dimensional speckle-tracking echocardiography in extremely preterm infants from birth to 1 year CA. The maturational patterns are ventricular specific. Bronchopulmonary dysplasia and pulmonary hypertension leave a negative impact on RV and IVS strain, while LV strain remains stable.

Long-Term Prognosis of Patients With Left Ventricular Noncompaction - Comparison Between Infantile and Juvenile Types

BACKGROUND

The natural history of left ventricular noncompaction (LVNC) is largely unsolved, so the aim of the present study was to clarify the clinical features and long-term prognosis of children with LVNC until adulthood.Methods and Results:We conducted a nationwide survey over 20 years and compared the clinical features, anatomical characteristics and long-term prognosis of 205 patients divided into 2 classifications: infantile type (diagnosed at <1 year of age: 108 cases) and juvenile type (diagnosed 1-15 years of age: 97 cases). Most patients diagnosed during infancy had heart failure (HF) at initial presentation (60.19%), while the majority of juvenile cases were asymptomatic (53.61%) but their event-free survival rate decreased gradually, because of later HF, thromboembolism and fatal arrhythmias. The initial LVEF was significantly lower in the infantile type and correlated with the thickness of the compacted layer in the LV posterior wall (LVPWC) and LV end-diastolic dimension (LVDD) Z-score, but not to the noncompacted to compacted layer (N/C) ratio. Survival analysis showed prognosis was similarly poor for both types after 2 decades. The significant risk factors for death, heart transplantation or implantable cardioverter-defibrillator insertion were congestive HF at diagnosis and lower LVPWC Z-score but not age of onset.

CONCLUSIONS

LVNC of both types showed poor long-term prognosis, therefore ongoing follow-up is recommended into adulthood. HF at diagnosis and LVPWC hypoplasia are major determinants of poor prognosis.

A new look at bronchopulmonary dysplasia: postcapillary pathophysiology and cardiac dysfunction

Pulmonary hypertension (PH) and right ventricular function are the focus of cardiovascular effects of bronchopulmonary dysplasia (BPD). We assessed cardiac indexes reflecting systemic afterload and pulmonary venous back pressure as pathophysiologic factors. Cardiac parameters were measured by conventional echocardiography in 20 preterm infants with severe BPD and compared with those of 10 preterm infants with no BPD and 20 healthy term infants. In infants with severe BPD, PH was noted in 5 (25%) by tricuspid regurgitation Doppler jet ≥2.8 m/s and in 15 (75%) by time to peak velocity/right ventricular ejection time <0.34. Among systemic cardiac indexes, significant impairment of diastolic measures was noted in the BPD group compared with infants with no BPD and term infants. The significance persisted after adjusting for gestational age and birth weight. These included transmitral E/A ratio (1.07 ± 0.07 vs. 0.91 ± 0.04 vs. 0.89 ± 0.09; P < 0.0001), isovolumic relaxation time (68.8 ± 3.9 vs. 58.5 ± 7.8 vs. 54.2 ± 5.7 ms ; P < 0.0001), mitral valve stroke volume (4.7 ± 0.7 vs. 5.6 ± 0.6 vs. 5.9 ± 0.1; P = 0.002), and myocardial performance index (0.33 ± 0.05 vs. 0.28 ± 0.01 vs. 0.27 ± 0.05; P = 0.03). Left ventricular output was significantly lower in the BPD cohort (183 ± 45 vs. 189 ± 9 vs. 191 ± 32 mL/kg/min; P = 0.03). Altered systemic (left-sided) cardiac function was noted in infants with BPD, which may lead to pulmonary venous congestion contributing to a continued need for respiratory support.

On Materials for Cardiac Tissue Engineering

In this essay the authors argue that chamber pressure dominates the biomechanics of the contraction cycle of the heart, while tissue stiffness dominates the relaxation cycle. This appears to be an under-recognized challenge in cardiac tissue engineering. Optimal approaches will involve constructing chambers or modulating the stiffness of the scaffold/substrate in synchrony with the beating cycle.

Recreating the Cardiac Microenvironment in Pluripotent Stem Cell Models of Human Physiology and Disease

The advent of human pluripotent stem cell (hPSC) biology has opened unprecedented opportunities for the use of tissue engineering to generate human cardiac tissue for in vitro study. Engineering cardiac constructs that recapitulate human development and disease requires faithful recreation of the cardiac niche in vitro. Here we discuss recent progress in translating the in vivo cardiac microenvironment into PSC models of the human heart. We review three key physiologic features required to recreate the cardiac niche and facilitate normal cardiac differentiation and maturation: the biochemical, biophysical, and bioelectrical signaling cues. Finally, we discuss key barriers that must be overcome to fulfill the promise of stem cell biology in preclinical applications and ultimately in clinical practice.

Myocardial Rotation and Torsion in Child Growth

Background

The speckle tracking echocardiography can benefit to assess the regional myocardial deformations. Although, previous reports suggested no significant change in left ventricular (LV) torsion with aging, there are certain differences in LV rotation at the base and apex. The purpose of this study was to evaluate the change and relationship of LV rotation for torsion with aging in children.

Methods

Forty healthy children were recruited and divided into two groups of twenty based on whether the children were preschool-age (2–6 years of age) or school-age (7–12 years of age). After obtaining conventional echocardiographic data, apical and basal short axis rotation were assessed with speckle tracking echocardiography. LV rotation in the basal and apical short axis planes was determined using six myocardial segments along the central axis.

Results

Apical and basal LV rotation did not show the statistical difference with increased age between preschool- and school-age children. Apical radial strain showed significant higher values in preschool-age children, especially at the anterior (52.8 ± 17.4% vs. 34.7 ± 23.2%, p < 0.02), lateral (55.8 ± 20.4% vs. 36.1 ± 22.7%, p < 0.02), and posterior segments (57.1 ± 17.6% vs. 38.5 ± 21.7%, p < 0.01). The torsion values did not demonstrate the statistical difference between two groups.

Conclusion

This study revealed the tendency of higher rotation values in preschool-age children than in school-age children. The lesser values of rotation and torsion with increased age during childhood warrant further investigation.

Heart and Cardiovascular Involvement in Patients with Mucopolysaccharidosis Type IVA (Morquio-A Syndrome)

BACKGROUND

Mucopolysaccharidosis (MPS) IVA is a rare lysosomal storage disorder with multiple skeletal and non-skeletal abnormalities requiring multiple surgical interventions. It is well known that patients with MPS IVA suffer from tachycardia, but cardiac and hemodynamic alterations have not been reported to date. We investigated the cardiovascular and hemodynamic alterations in patients with MPS IVA and developed a possible patho-mechanism for cardiovascular deterioration during anesthesia.

MATERIAL AND METHODS

In this observational study, serial cardiac examinations were performed in 54 patients with MPS IVA who were followed at the Children's Hospital of the Mainz Medical University (Mainz, Germany) between 1991 and 2014 (follow-up 1-24 years; median 5.8 years). Results were compared with data from a large central European cohort of more than 2000 healthy infants and children.

RESULTS

None of the patients had arterial hypertension, but 4% had evidence of increased pulmonary artery pressure. Patients developed aortic root extension up to 6.9 standard deviations above normal. Left-sided valve leaflet thickening occurred in 26 patients (five with valve disease). Patients had lower left ventricular dimensions (z: -1.02±0.1), lower stroke volumes (z: -2.3±0.17), lower left ventricular mass (z: -1.5±0.21), but higher wall thickness (z: +0.8±0.16), and higher work index (z: +2.5±0.2) compared to healthy control subjects. Cardiac output was preserved by an increase in heart rate of 21%. Sixty % of patients showed impaired diastolic filling; heart rate (99.0±1.8 vs. 92.0±2.1 bpm), age (18.0±1.8 vs. 14.2±1 years), and cardiothoracic ratio (61.6±3.6% vs. 55±4.2%) of these patients were higher compared to those with normal filling.

CONCLUSIONS

The results of this study suggest an age-progressive disproportion of the intra-thoracic organs of patients with MPS IVA, which is accompanied by aortic root extension and thickened left ventricles, with reduced stroke volumes, impaired diastolic filling patterns, and increased heart rates.

Progressive intermediate-term improvement in ventricular and atrioventricular interaction after transcatheter pulmonary valve replacement in patients with right ventricular outflow tract obstruction

BACKGROUND

Relief of postoperative right ventricular outflow tract (RVOT) obstruction with transcatheter pulmonary valve replacement (TPVR) results in functional improvement in the short term which we investigated at baseline (BL), early follow-up (FU), and midterm FU after TPVR.

METHODS

Echocardiography and cardiopulmonary exercise testing were performed at BL and at early (median 6 months) and midterm FU (median 2.5years) after TPVR.

RESULTS

Patients with RVOT obstruction (n=22, median age 17years) were studied. The max RVOT Doppler gradient fell from BL to early FU (60±24 to 26±8mm Hg, P<.001). Left ventricular (LV) end-diastolic and stroke volume increased at early FU (both P<.001) without further change, whereas LV ejection fraction improved throughout FU (P<.001). LV end-systolic and diastolic eccentricity (leftward septal displacement) improved early (both P≤.003), and end-diastolic eccentricity improved further at midterm FU (P=.02). Furthermore, whereas mitral inflow A wave velocity increased (P=.003), the LV A' velocity declined early (P=.007) without further change at midterm. RV systolic and early diastolic function was impaired at BL. Whereas RV strain improved partially at early and midterm FU (P≤.02), RV E' velocity did not improve throughout FU. Mildly impaired LV strain at BL fully recovered by midterm FU (P≤.002). Peak oxygen uptake improved at early and midterm FU (all P≤.003).

CONCLUSIONS

Patients with RVOT obstruction had biventricular systolic and diastolic dysfunction at BL. Relieving RVOT obstruction with TPVR reduced adverse ventricular and compensatory atrioventricular interaction, resulting in progressive biventricular functional improvement and remodeling at early and midterm FU.

Systolic-diastolic functional coupling in healthy children and in those with dilated cardiomyopathy

Systolic and diastolic function affect dilated cardiomyopathy (DCM) outcomes. However, systolic-diastolic coupling, as a distinct characteristic, may itself affect function but is poorly characterized. We hypothesized that echocardiographic left ventricular (LV) longitudinal systolic tissue velocities (S') correlate with diastolic longitudinal velocities (E') and that their relationship is associated with ventricular function and that this relationship is impaired in pediatric DCM. We analyzed data from the Pediatric Heart Network Ventricular Volume Variability study, using linear regression and generalized additive modeling to assess relationships between S' and E' at the lateral and septal mitral annulus. We explored relationships between the systolic:diastolic (S:D) coupling ratio (S':E' relative to age) and ventricular function. Up to 4 echocardiograms from 130 DCM patients (mean age: 9.3 ± 6.1 yr) and 1 echocardiogram from each of 591 healthy controls were analyzed. S' and E' were linearly related in controls (r = 0.64, P < 0.001) and DCM (r = 0.83, P < 0.001). In DCM, the magnitude of association between S' and E' was reduced with progressive ventricular remodeling. The S:D ratio was more strongly associated with LV function in controls vs. DCM. The septal S:D ratio was higher (presumed worse) in DCM vs. controls (0.69 ± 0.13 vs. 0.62 ± 0.12, P = 0.001). A higher septal S:D ratio was associated with worse LV dimensions (parameter estimate: 0.0061, P = 0.004), mass (parameter estimate: 0.0074, P = 0.002), ejection fraction (parameter estimate: -0.0303, P = 0.024), and inflow propagation (parameter estimate: -0.3538, P < .001). S:D coupling becomes weaker in DCM with LV remodeling and dysfunction. The S:D coupling ratio may be useful to assess coupling, warranting study in relation to patient outcomes.

Health-Related Quality of Life and Functional Status Are Associated with Cardiac Status and Clinical Outcome in Children with Cardiomyopathy

OBJECTIVES

To measure the health-related quality of life (HRQOL) and functional status of children with cardiomyopathy and to determine whether they are correlated with sociodemographics, cardiac status, and clinical outcomes.

STUDY DESIGN

Parents of children in the Pediatric Cardiomyopathy Registry completed the Child Health Questionnaire (CHQ; age ≥ 5 years) and Functional Status II (Revised) (age ≤ 18 years) instruments. Linear and Cox regressions were used to examine hypothesized associations with HRQOL.

RESULTS

The 355 children evaluated at ≥ 5 years (median 8.6 years) had lower functioning (CHQ Physical and Psychosocial Summary Scores 41.7 ± 14.4 and 47.8 ± 10.7) than that of healthy historical controls. The most extreme CHQ domain score, Parental Impact-Emotional, was one SD below normal. Younger age at diagnosis and smaller left ventricular end-diastolic dimension z score were associated independently with better physical functioning in children with dilated cardiomyopathy. Greater income/education correlated with better psychosocial functioning in children with hypertrophic and mixed/other types of cardiomyopathy. In the age ≥ 5 year cohort, lower scores on both instruments predicted earlier death/transplant and listing for transplant in children with dilated and mixed/other types of cardiomyopathy (P < .001). Across all ages (n = 565), the Functional Status II (Revised) total score was 87.1 ± 16.4, and a lower score was associated with earlier death/transplant for all cardiomyopathies.

CONCLUSIONS

HRQOL and functional status in children with cardiomyopathy is on average impaired relative to healthy children. These impairments are associated with older age at diagnosis, lower socioeconomic status, left ventricular size, and increased risk for death and transplant. Identification of families at risk for functional impairment allows for provision of specialized services early in the course of disease.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00005391.

New targets for monitoring and therapy in Barth syndrome

PURPOSE

Barth syndrome (BTHS), an X-linked disorder caused by defects in TAZ, is the only known single-gene disorder of cardiolipin remodeling. We hypothesized that through analysis of affected individuals, we would gain a better understanding of the range of clinical features and identify targets for monitoring and therapy.

METHODS

We conducted a multidisciplinary investigation involving 42 patients with BTHS, including echocardiograms, muscle strength testing, functional exercise capacity testing, physical activity assessments, cardiolipin analysis, 3-methylglutaconic acid analysis, and review of genotype data. We analyzed data points to provide a quantitative spectrum of disease characteristics and to identify relationships among phenotype, genotype, and relevant metabolites.

RESULTS

Echocardiography revealed considerable variability in cardiac features. By contrast, almost all patients had significantly reduced functional exercise capacity. Multivariate analysis revealed significant relationships between cardiolipin ratio and left ventricular mass and between cardiolipin ratio and functional exercise capacity. We additionally identified genotypes associated with a less severe metabolic and clinical profile.

CONCLUSION

We defined previously unrecognized metabolite/phenotype/genotype relationships, established targets for therapeutic monitoring, and validated avenues for clinical assessment. In addition to providing insight into BTHS, these studies also provide insight into the myriad of multifactorial disorders that converge on the cardiolipin pathway.Genet Med 18 10, 1001-1010.

Intensified Chemotherapy With Dexrazoxane Cardioprotection in Newly Diagnosed Nonmetastatic Osteosarcoma: A Report From the Children's Oncology Group

BACKGROUND

Although chemotherapy has improved outcome of osteosarcoma, 30-40% of patients succumb to this disease. Survivors experience substantial morbidity and mortality from anthracycline-induced cardiotoxicity. We hypothesized that the cardioprotectant dexrazoxane would (i) support escalation of the cumulative doxorubicin dose (600 mg/m(2)) and (ii) not interfere with the cytotoxicity of chemotherapy measured by necrosis grading in comparison to historical control data.

PROCEDURE

Children and adolescents with nonmetastatic osteosarcoma were treated with MAP (methotrexate, doxorubicin, cisplatin) or MAPI (MAP/ifosfamide). Dexrazoxane was administered with all doxorubicin doses. Cardioprotection was assessed by measuring left ventricular fractional shortening. Interference with chemotherapy-induced cytotoxicity was determined by measuring tumor necrosis after induction chemotherapy. Feasibility of intensifying therapy with either high cumulative-dose doxorubicin or high-dose ifosfamide/etoposide was evaluated for "standard responders" (SR, <98% tumor necrosis at definitive surgery).

RESULTS

Dexrazoxane did not compromise response to induction chemotherapy. With doxorubicin (450-600 mg/m(2)) and dexrazoxane, grade 1 or 2 left ventricular dysfunction occurred in five patients; 4/5 had transient effects. Left ventricular fractional shortening z-scores (FSZ) showed minimal reductions (0.0170  ±  0.009/week) over 78 weeks. Two patients (<1%) had secondary leukemia, one as a first event, a similar rate to what has been observed in prior trials. Intensification with high-dose ifosfamide/etoposide was also feasible.

CONCLUSIONS

Dexrazoxane cardioprotection was safely administered. It did not impair tumor response or increase the risk of secondary malignancy. Dexrazoxane allowed for therapeutic intensification increasing the cumulative doxorubicin dose in SR to induction chemotherapy. These findings support the use of dexrazoxane in children and adolescents with osteosarcoma.

Cardioprotection and Safety of Dexrazoxane in Patients Treated for Newly Diagnosed T-Cell Acute Lymphoblastic Leukemia or Advanced-Stage Lymphoblastic Non-Hodgkin Lymphoma: A Report of the Children's Oncology Group Randomized Trial Pediatric Oncology Group 9404

PURPOSE

To determine the oncologic efficacy, cardioprotective effectiveness, and safety of dexrazoxane added to chemotherapy that included a cumulative doxorubicin dose of 360 mg/m(2) to treat children and adolescents with newly diagnosed T-cell acute lymphoblastic leukemia (T-ALL) or lymphoblastic non-Hodgkin lymphoma (L-NHL).

PATIENTS AND METHODS

Patients were treated on Pediatric Oncology Group Protocol POG 9404, which included random assignment to treatment with or without dexrazoxane given as a bolus infusion immediately before every dose of doxorubicin. Cardiac effects were assessed by echocardiographic measurements of left ventricular function and structure.

RESULTS

Of 573 enrolled patients, 537 were eligible, evaluable, and randomly assigned to an arm with or without dexrazoxane. The 5-year event-free survival (with standard error) did not differ between groups: 77.2% (2.7%) for the dexrazoxane group versus 76.0% (2.7%) for the doxorubicin-only group (P = .9). The frequencies of severe grade 3 or 4 hematologic toxicity, infection, CNS events, and toxic deaths were similar in both groups (P ranged from .26 to .64). Of 11 second malignancies, eight occurred in patients who received dexrazoxane (P = .17). The mean left ventricular fractional shortening, wall thickness, and thickness-to-dimension ratio z scores measured 3 years after diagnosis were worse in the doxorubicin-alone group (n = 55 per group; P ≤ .01 for all comparisons). Mean fractional shortening z scores measured 3.5 to 6.4 years after diagnosis remained diminished and were lower in the 21 patients who received doxorubicin alone than in the 31 patients who received dexrazoxane (-2.03 v -0.24; P ≤ .001).

CONCLUSION

Dexrazoxane was cardioprotective and did not compromise antitumor efficacy, did not increase the frequencies of toxicities, and was not associated with a significant increase in second malignancies with this doxorubicin-containing chemotherapy regimen. We recommend dexrazoxane as a cardioprotectant for children and adolescents who have malignancies treated with anthracyclines.

Cardiomyopathy Phenotypes and Outcomes for Children With Left Ventricular Myocardial Noncompaction: Results From the Pediatric Cardiomyopathy Registry

BACKGROUND

Left ventricular noncompaction (LVNC) is a distinct form of cardiomyopathy characterized by hypertrabeculation of the left ventricle. The LVNC phenotype may occur in isolation or with other cardiomyopathy phenotypes. Prognosis is incompletely characterized in children.

METHODS AND RESULTS

According to diagnoses from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry from 1990 to 2008, 155 of 3,219 children (4.8%) had LVNC. Each LVNC patient was also classified as having an associated echocardiographically diagnosed cardiomyopathy phenotype: dilated (DCM), hypertrophic (HCM), restrictive (RCM), isolated, or indeterminate. The time to death or transplantation differed among the phenotypic groups (P = .035). Time to listing for cardiac transplantation significantly differed by phenotype (P < .001), as did time to transplantation (P = .015). The hazard ratio for death/transplantation (with isolated LVNC as the reference group) was 4.26 (95% confidence interval [CI] 0.78-23.3) for HCM, 6.35 (95% CI 1.52-26.6) for DCM, and 5.66 (95% CI 1.04-30.9) for the indeterminate phenotype. Most events occurred in the 1st year after diagnosis.

CONCLUSIONS

LVNC is present in at least 5% of children with cardiomyopathy. The specific LVNC-associated cardiomyopathy phenotype predicts the risk of death or transplantation and should inform clinical management.

Noncoronary inflammation in Kawasaki disease is associated with abnormal myocardial deformation in the acute phase

BACKGROUND

Patients with Kawasaki disease (KD) are at risk for developing coronary artery lesions, but the association of noncoronary changes such as mitral regurgitation (MR) and/or pericardial effusion (PE) with cardiac mechanics in the acute phase of KD has not been previously described. The aim of this study was to test the hypothesis that these noncoronary markers for carditis are associated with abnormalities in strain (ε) and strain rate (SR) in patients with MR or PE not appreciated by conventional echocardiography.

METHODS

Longitudinal and circumferential ε and SR analyses were retrospectively performed on patients with KD. Patients with and without MR or PE were compared. Strain values were also compared between patients with and without coronary artery lesions. Values for ejection fraction, shortening fraction, and clinical laboratory parameters were correlated with MR or PE. Follow-up echocardiographic outcomes were recorded at the first encounter after initial diagnosis. Follow-up ε and SR data were also obtained in the group with MR or PE and altered ventricular mechanics at diagnosis.

RESULTS

Of the 110 patients reviewed, 92 had appropriate image quality for either longitudinal ε and SR or circumferential ε and SR analysis. Twenty-eight patients (30%) had either MR or PE. Longitudinal ε and SR were significantly decreased in patients with MR or PE compared with patients without MR or PE (ε: -16.4 ± 4.0% vs -19.0 ± 3.7%, P = .004; SR: -1.3 ± 0.7 vs -1.6 ± 0.4 sec(-1), P = .03). No significant difference in longitudinal ε or SR was noted between patients with and without coronary artery lesions (ε: -17.9 ± 4.1% vs -17.8 ± 3.8%, P = .50; SR: -1.5 ± 0.3 vs -1.6 ± 0.8 sec(-1), P = .50). In the group with abnormal coronary arteries, presence of MR or PE was correlated with decreased longitudinal ε (-16.1 ± 3.6% vs -18.9 ± 3.4%, P = .02), without a significant difference in longitudinal SR (-1.6 ± 0.4 vs -1.5 ± 0.4 sec(-1), P = .20). At approximately 3-week follow-up (21.3 ± 15.8 days), longitudinal ε and SR for the group with MR or PE had increased significantly compared with diagnosis (ε: -16.4 ± 4.3% vs -18.6 ± 0.5%, P = .03; SR: -1.3 ± 0.6 vs -1.8 ± 0.4 sec(-1), P = .008), coincident with resolution of MR or PE. In both groups, erythrocyte sedimentation rate and C-reactive protein were elevated (85.3 ± 36.2 mm/h vs 75.1 ± 33.1 mm/h [P = .34] and 12.3 ± 6.7 vs 11.7 ± 8.2 mg/dL [P = .83]), but only modest correlations were noted between longitudinal ε and elevated erythrocyte sedimentation rate (r = 0.52, P = .01; confidence interval, 0.10-0.80) and C-reactive protein (r = 0.50, P = .02; confidence interval, 0.10-0.80) in patients with MR or PE. Shortening fraction and ejection fraction were within the normal range in both groups.

CONCLUSIONS

Patients presenting with KD with MR or PE at diagnosis are likely to have altered ventricular mechanics compared with patients with KD without MR or PE despite normal conventional echocardiographic measures of function. There is no significant difference in ventricular mechanics when comparing patients with KD with coronary ectasia or aneurysms and those without coronary lesions. Presence of abnormal ε in patients with KD with altered ventricular mechanics correlates modestly with laboratory inflammatory markers. Peak systolic longitudinal ε and SR increased significantly at 3-week follow-up compared with initial diagnosis, coincident with resolution of MR or PE.

Recommendations for cardiomyopathy surveillance for survivors of childhood cancer: a report from the International Late Effects of Childhood Cancer Guideline Harmonization Group

Survivors of childhood cancer treated with anthracycline chemotherapy or chest radiation are at an increased risk of developing congestive heart failure. In this population, congestive heart failure is well recognised as a progressive disorder, with a variable period of asymptomatic cardiomyopathy that precedes signs and symptoms. As a result, several clinical practice guidelines have been developed independently to help with detection and treatment of asymptomatic cardiomyopathy. These guidelines differ with regards to definitions of at-risk populations, surveillance modality and frequency, and recommendations for interventions. Differences between these guidelines could hinder the effective implementation of these recommendations. We report on the results of an international collaboration to harmonise existing cardiomyopathy surveillance recommendations using an evidence-based approach that relied on standardised definitions for outcomes of interest and transparent presentation of the quality of the evidence. The resultant recommendations were graded according to the quality of the evidence and the potential benefit gained from early detection and intervention.

Dissipative energy loss within the left ventricle detected by vector flow mapping in children: Normal values and effects of age and heart rate

BACKGROUND

Vector flow mapping (VFM) is a novel echocardiographic technology which enables visualization of the intraventricular flow velocity vector. Dissipative energy loss (EL) derived from the velocity vector field of intraventricular blood flow is considered to reflect the efficiency of blood flow, and could be an indicator of left ventricular function. We aimed to determine the reference values of the EL derived from VFM within the left ventricle.

METHODS

VFM analysis was performed using echocardiography in 64 healthy children. The velocity vector fields of the intra-left ventricular blood flow were obtained from the apical 5-chamber view, and the EL values during systole and diastole were calculated. The measurements were averaged over three cardiac cycles, and indexed to body surface area (BSA).

RESULTS

The mean subject age was 6.8±4.3 years. The mean EL was 4.10±2.35mW/m/m(2) BSA during systole and 16.24±11.63mW/m/m(2) BSA during diastole. On multivariate analysis, age and heart rate (HR) were independent predictors of systolic EL, whereas age, HR, and E wave peak velocity were independent predictors of diastolic EL. The regression equations used to predict the BSA-indexed systolic and diastolic EL were as follows: log10 (systolic EL)=-0.0332-0.00213×age (months)+0.00789×HR (beats/min) (adjusted R(2), 0.833; p<0.0001); and log10 (diastolic EL)=0.277-0.00346×age (months)+0.00570×HR (beats/min)+0.00564×E wave peak velocity (cm/s) (adjusted R(2), 0.867; p<0.0001).

CONCLUSIONS

The systolic and diastolic EL were positively correlated with HR and negatively correlated with age. Moreover, the diastolic EL was positively correlated with the E wave peak velocity. The present study provides reference values for the systolic and diastolic EL that can be used in future studies examining patients with heart disease.