Allometric normalization of cardiac measures: producing better, but imperfect, accuracy

Challenges in the diagnosis of heart failure with preserved ejection fraction in individuals with obesity

The rising prevalence of obesity and its association with heart failure with preserved ejection fraction (HFpEF) highlight an urgent need for a diagnostic approach tailored to this population. Diagnosing HFpEF is hampered by the lack of a single non-invasive diagnostic criterion. While this makes a firm diagnosis of HFpEF already notoriously difficult in the general population, it is even more challenging in individuals with obesity. The challenges stem from a range of factors, including the use of body mass index as a conceptually suboptimal indicator of health risks associated with increased body mass, symptom overlap between HFpEF and obesity, limitations in physical examination, difficulties in electrocardiographic and echocardiographic evaluation, and reduced diagnostic sensitivity of natriuretic peptides in individuals with obesity. In this review, we examine these diagnostic challenges and propose a diagnostic algorithm specifically tailored to improve the accuracy and reliability of HFpEF diagnosis in this growing patient demographic.

The impact of echocardiographic indexation to evaluate cardiac reverse remodeling throughout pregnancy and postpartum

INTRODUCTION AND OBJECTIVES

Echocardiography guidelines suggest normalizing left ventricular (LV) volumes and mass (LVM) to body size. During pregnancy, continuous weight variation impacts on body surface area (BSA) calculation, limiting the longitudinal analysis of cardiac remodeling (CR) and reverse remodeling (RR) variables. Our aim was to identify the most common indexing methodologies in the literature on pregnant populations through a systematic review; and, to compare four scaling methods: (i) none (absolute values); (ii) indexing to the BSA before pregnancy; (iii) allomeric indexing; and (iv) indexing to BSA measured at the same day of cardiac assessment, using an illustrative example.

METHODS

We performed a systematic review of CR and RR during pregnancy and post-partum, using two databases. We included studies reporting longitudinal echocardiographic analysis of cardiac chamber volumes in humans. We used a prospective cohort study of healthy pregnant women who underwent four echocardiographic evaluations during pregnancy and postpartum, as an illustrative example.

RESULTS

Twenty-seven studies were included, most studies indexed to BSA measured at each evaluation moment (n=21). Within-subjects design was the most reported to analyse longitudinal data (n=17). Indexation to the pre-pregnancy BSA or application of allometric indexes revealed a higher effect than BSA measured at each evaluation and an equal effect to not indexing using within-subjects design. The within-subjects designs also revealed a higher effect size value than the between-subjects design for longitudinal analysis of LVM adaptations during pregnancy and postpartum.

CONCLUSION(S)

This study concludes that indexation methods do not impact the clinical interpretation of longitudinal echocardiographic assessment but highlights the need to harmonize normalization procedures during pregnancy.

Improved identification of left atrial enlargement in patients with obesity

Accurate standardization of left atrium volume (LAV) in patients with obesity is challenging. The aim of this study was to investigate and to examine the relation between LAV indexed to height2 and left atrial function in patients with moderate to severe obesity. Echocardiograms of patients with moderate to severe obesity (body mass index (BMI) ≥ 35 kg/m2) without known cardiac disease were analyzed. LAV was indexed to body surface area (BSA) and height2, and patients were divided into those with or without left atrial enlargement (LAE) based on normalization using either BSA (LAEbsa) or height2 (LAEh2). Using speckle tracking echocardiography, LA reservoir strain (LASr), LA conduit strain (LAScd), and LA contractile strain (LASct) were assessed as a measure of LA function. LA dysfunction was defined as LASct < 14%. A total of 142 patients were included in the analysis of whom 54.2% had LAEh2 and 18.3% LAEBSA. The LAEh2 group had significantly lower LASct (12.2% ± 3.2% vs. 13.6% ± 4.5%, p = 0.019) as compared to the patients without LAEh2. Significantly more patients with LA dysfunction would be correctly identified by LAEh2 than by LAEBSA (41.5% vs. 15.0%, p < 0.001). In patients with moderate to severe obesity, the use of LAEh2 identified significantly more patients with decreased LA function. LAVh2 should be preferred over LAVBSA in patients with moderate to severe obesity.

Diastolic function in chronic kidney disease

Chronic kidney disease (CKD) is characterized by clustered age-independent concentric left ventricular (LV) geometry, geometry-independent systolic dysfunction and age and heart rate-independent diastolic dysfunction. Concentric LV geometry is always associated with echocardiographic markers of abnormal LV relaxation and increased myocardial stiffness, two hallmarks of diastolic dysfunction. Non-haemodynamic mechanisms such as metabolic and electrolyte abnormalities, activation of biological pathways and chronic exposure to cytokine cascade and the myocardial macrophage system also impact myocardial structure and impair the architecture of the myocardial scaffold, producing and increasing reactive fibrosis and altering myocardial distensibility. This review addresses the pathophysiology of diastole in CKD and its relations with cardiac mechanics, haemodynamic loading, structural conditions, non-haemodynamic factors and metabolic characteristics. The three mechanisms of diastole will be examined: elastic recoil, active relaxation and passive distensibility and filling. Based on current evidence, we briefly provide methods for quantification of diastolic function and discuss whether diastolic dysfunction represents a distinct characteristic in CKD or a proxy of the severity of the cardiovascular condition, with the potential to be predicted by the general cardiovascular phenotype. Finally, the review discusses assessment of diastolic function in the context of CKD, with special emphasis on end-stage kidney disease, to indicate whether and when in-depth measurements might be helpful for clinical decision making in this context.

Heart-brain connections: Phenotypic and genetic insights from magnetic resonance images

Cardiovascular health interacts with cognitive and mental health in complex ways, yet little is known about the phenotypic and genetic links of heart-brain systems. We quantified heart-brain connections using multiorgan magnetic resonance imaging (MRI) data from more than 40,000 subjects. Heart MRI traits displayed numerous association patterns with brain gray matter morphometry, white matter microstructure, and functional networks. We identified 80 associated genomic loci (P < 6.09 × 10-10) for heart MRI traits, which shared genetic influences with cardiovascular and brain diseases. Genetic correlations were observed between heart MRI traits and brain-related traits and disorders. Mendelian randomization suggests that heart conditions may causally contribute to brain disorders. Our results advance a multiorgan perspective on human health by revealing heart-brain connections and shared genetic influences.

Defining left ventricular remodeling using lean body mass allometry: a UK Biobank study

PURPOSE

The geometric patterns of ventricular remodeling are determined using indexed left ventricular mass (LVM), end-diastolic volume (LVEDV) and concentricity, most often measured using the mass-to-volume ratio (MVR). The aims of this study were to validate lean body mass (LBM)-based allometric coefficients for scaling and to determine an index of concentricity that is independent of both volume and LBM.

METHODS

Participants from the UK Biobank who underwent both CMR and dual-energy X-ray absorptiometry (DXA) during 2014-2015 were considered (n = 5064). We excluded participants aged ≥ 70 years or those with cardiometabolic risk factors. We determined allometric coefficients for scaling using linear regression of the logarithmically transformed ventricular remodeling parameters. We further defined a multiplicative allometric relationship for LV concentricity (LVC) adjusting for both LVEDV and LBM.

RESULTS

A total of 1638 individuals (1057 female) were included. In subjects with lower body fat percentage (< 25% in males, < 35% in females, n = 644), the LBM allometric coefficients for scaling LVM and LVEDV were 0.85 ± 0.06 and 0.85 ± 0.03 respectively (R² = 0.61 and 0.57, P < 0.001), with no evidence of sex-allometry interaction. While the MVR was independent of LBM, it demonstrated a negative association with LVEDV in (females: r = - 0.44, P < 0.001; males: - 0.38, P < 0.001). In contrast, LVC was independent of both LVEDV and LBM [LVC = LVM/(LVEDV^0.40 × LBM^0.50)] leading to increased overlap between LV hypertrophy and higher concentricity.

CONCLUSIONS

We validated allometric coefficients for LBM-based scaling for CMR indexed parameters relevant for classifying geometric patterns of ventricular remodeling.

Height Versus Body Surface Area to Normalize Cardiovascular Measurements in Children Using the Pediatric Heart Network Echocardiographic Z-Score Database

Normalizing cardiovascular measurements for body size allows for comparison among children of different ages and for distinguishing pathologic changes from normal physiologic growth. Because of growing interest to use height for normalization, the aim of this study was to develop height-based normalization models and compare them to body surface area (BSA)-based normalization for aortic and left ventricular (LV) measurements. The study population consisted of healthy, non-obese children between 2 and 18 years of age enrolled in the Pediatric Heart Network Echo Z-Score Project. The echocardiographic study parameters included proximal aortic diameters at 3 locations, LV end-diastolic volume, and LV mass. Using the statistical methodology described in the original project, Z-scores based on height and BSA were determined for the study parameters and tested for any clinically significant relationships with age, sex, race, ethnicity, and body mass index (BMI). Normalization models based on height versus BSA were compared among underweight, normal weight, and overweight (but not obese) children in the study population. Z-scores based on height and BSA were calculated for the 5 study parameters and revealed no clinically significant relationships with age, sex, race, and ethnicity. Normalization based on height resulted in lower Z-scores in the underweight group compared to the overweight group, whereas normalization based on BSA resulted in higher Z-scores in the underweight group compared to the overweight group. In other words, increasing BMI had an opposite effect on height-based Z-scores compared to BSA-based Z-scores. Allometric normalization based on height and BSA for aortic and LV sizes is feasible. However, height-based normalization results in higher cardiovascular Z-scores in heavier children, and BSA-based normalization results in higher cardiovascular Z-scores in lighter children. Further studies are needed to assess the performance of these approaches in obese children with or without cardiac disease.

A Systematic Review of Scaling Left Atrial Size: Are Alternative Indexation Methods Required for an Increasingly Obese Population?

BACKGROUND

Left atrial (LA) size indexed to body surface area (BSA) is a clinically important marker of cardiovascular prognosis. However, indexation using a scaling variable such as BSA has inherent flaws, particularly in an obese population. The aim of this study was to determine whether alternative indexation methods may more accurately scale for LA size.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used to execute a structured search of medical databases, to identify articles discussing alternative methods of LA indexation in echocardiography. Articles that stratified indexed LA size by obesity class were also included. Two independent reviewers identified relevant articles and extracted baseline characteristics, alternative indexation methods, scaling variables, obesity class characteristics, and correlation coefficients.

RESULTS

A total of 3,804 articles were found in the database search after removing duplicates. After abstract and full-text screening, 13 relevant articles were identified. Twelve studies used alternative methods of LA indexation, of which nine reported allometric indices. Seven of the included studies reported LA size by obesity class, of which six reported alternative indices. Correlation coefficients plotted for indexed LA size against absolute measured LA size showed that allometric indices (specifically to height) were more likely to maintain proportionality to body size compared with isometric indices such as BSA. Allometric indices were less likely to overcorrect for body size compared with isometric indices.

CONCLUSIONS

Compared with isometric indexation to BSA, allometric indexation (specifically to height) improves scaling of LA volumes to maintain proportionality and avoid overcorrection for body size.

Focal reduction in left ventricular 123I-metaiodobenzylguanidine uptake and impairment in systolic function in patients with Anderson-Fabry disease

BACKGROUND

Abnormalities of cardiac sympathetic innervation have been demonstrated in Anderson-Fabry disease (AFD). We aimed to investigate the relationship between regional left ventricular (LV) denervation and regional function abnormalities.

METHODS

Twenty-four AFD patients (43.7 ± 12.8 years) were studied by 123I-metaiodobenzylguanidine (MIBG) cardiac imaging and speckle-tracking echocardiography. Segmental tracer uptake was estimated according to 0 to 4 score, and total defect score (TDS) was calculated for each patient.

RESULTS

Segmental longitudinal strain worsened as MIBG uptake score increased (P < 0.001). By ROC analysis, a segmental longitudinal strain > - 16.2% predicted a segmental MIBG uptake score ≥1, with 79.7% sensitivity and 65.3% specificity. Segmental MIBG uptake defects were found in 13 out 24 AFD patients. LV mass index (60.8 ± 10.1 vs. 41.4 ± 9.8 g/h2.7), relative wall thickness (0.51 ± 0.06 vs. 0.40 ± 0.06), systolic pulmonary artery pressure (35.2 ± 6.7 vs. 27.2 ± 4.2 mmHg), and longitudinal strain (- 14.3 ± 2.7 vs. -19.4 ± 1.8%) were significantly higher in patients with segmental defect (all P < 0.01). At multivariate linear regression analysis, global longitudinal strain was independently associated with TDS (B = 3.007, 95% confidence interval 1.384 to 4.630, P = 0.001).

CONCLUSIONS

Reduced cardiac MIBG uptake reflects the severity of cardiac involvement in AFD patients. LV longitudinal function impairment seems to be an earlier disease feature than regional myocardial denervation.

Sex Disparity in Cardiovascular Disease Outcomes: Do Our Current Echocardiographic Reference Ranges Measure Up?

Reducing inequity in access to health care and disparity in health outcomes remain key objectives in cardiovascular medicine. Echocardiography is often the primary diagnostic tool used to detect cardiovascular disease (CVD), and relies on comparison with published reference ranges to appropriately detect pathology. Our understanding of the contribution of age, sex and ethnicity to quantification of cardiac size is improving, but cardiovascular disease management guidelines have yet to evolve. While recently, sex, age and ethnicity-specific reference values have been produced, treatment thresholds in many clinical guidelines do not differentiate between sexes. As a result, in order to reach management thresholds, women are often required to have more severe pathology. In order to reduce potential disadvantage to women, future research efforts should be directed to develop more personalised treatment approaches by identification of sex-appropriate management thresholds.

Dilatation of the Ascending Aorta in Turner Syndrome: Influence of Bicuspid Aortic Valve Morphology and Body Composition

BACKGROUND

Aortic dilatation and bicuspid aortic valve (BAV) are frequent in Turner syndrome (TS). Due to short stature, aortic size index (ASI)-ascending aortic diameter (AD)/body surface area (BSA)-is used to identify aortic dilatation in TS patients. We sought to: 1) describe echocardiographic findings in the largest cohort of Australian women with TS; 2) assess if ASI progresses differently with age in TS BAV compared to non-syndromic BAV; and 3) determine whether adjustment of AD for body composition may be superior to BSA indexation.

METHODS

Transthoracic echocardiography (TTE) data were retrospectively collected on 125 women with TS. Body composition was quantified by dual energy X-ray absorptiometry (DXA) in 60 women within 6 months of baseline TTE. Age-matched females with non-syndromic BAV (n=170) were used as controls for TS patients with BAV.

RESULTS

Mean age of TS women was 28±16 years, and mean height and BSA were 141.6±21.7 cm and 1.4±0.4 m², respectively. Mean AD was 2.5±0.8 cm, and ASI 2.0±0.6 cm/m². Aortic dilatation (ASI >2.0 cm/m²) was present in 42 (34%) patients. Turner syndrome women with BAV (n=34; 27%) had a larger ASI than those with tri-leaflet AV (2.2±0.4 cm/m² vs. 1.7±0.3 cm/m², p<0.001). In the pooled BAV cohort, TS patients had a higher baseline ASI (2.2±0.4 cm/m² vs. 2.1±0.3 cm/m², p=0.02) and greater increase in ASI with age (0.21 mm/m²/year vs. 0.10 mm/m²/year, p=0.01) compared to non-syndromic BAV patients. DXA fat-free mass (r=0.33, p=0.01) and lean mass (r=0.32, p=0.02) correlated with AD, as did BSA (r=0.62, p<0.001).

CONCLUSION

Turner syndrome women with BAV have a greater degree of baseline aortic dilatation and a twofold faster increase in aortic dimension with age when compared to matched women with non-syndromic BAV. Several DXA-derived body composition parameters correlate with aortic size in TS, however BSA appears to be the most robust method of indexation.

Both male and female obese ZSF1 rats develop cardiac dysfunction in obesity-induced heart failure with preserved ejection fraction

Heart failure with a preserved ejection fraction (HFpEF) is associated with multiple comorbidities, such as old age, hypertension, type 2 diabetes and obesity and is more prevalent in females. Although the male obese ZSF1 rat has been proposed as a suitable model to study the development of diastolic dysfunction and early HFpEF, studies in female animals have not been performed yet. Therefore, we aimed to characterize the cardiac phenotype in female obese ZSF1 rats and their lean counterparts. Additionally, we aimed to investigate whether differences exist in disease progression in obese male and female ZSF1 rats. Therefore, male and female ZSF1 rats, lean as well as obese (N = 6-9/subgroup), were used. Every two weeks, from 12 to 26 weeks of age, systolic blood pressure and echocardiographic measurements were performed, and venous blood was sampled. Female obese ZSF1 rats, as compared to female lean ZSF1 rats, developed diastolic dysfunction with cardiac hypertrophy and fibrosis in the presence of severe dyslipidemia, increased plasma growth differentiation factor 15 and mild hypertension, and preservation of systolic function. Although obese female ZSF1 rats did not develop hyperglycemia, their diastolic dysfunction was as severe as in the obese males. Taken together, the results from the present study suggest that the female obese ZSF1 rat is a relevant animal model for HFpEF with multiple comorbidities, suitable for investigating novel therapeutic interventions.

Prominent longitudinal strain reduction of left ventricular basal segments in treatment-naïve Anderson-Fabry disease patients

AIMS

Little is known about regional longitudinal strain (LS) distribution in early stages of Anderson-Fabry disease (AFD) cardiomyopathy. We investigated regional left ventricular (LV) patterns of LS strain and base-to-apex behaviour of LS in treatment-naïve AFD patients.

METHODS AND RESULTS

Twenty-three consecutive AFD patients at diagnosis and 23 healthy controls without cardiovascular risk factors and matched for age and sex to the patients, underwent a comprehensive evaluation of target organs. An echo-Doppler exam, including determination of regional and global LS strain (GLS) was obtained. The average LS of 6 basal (BLS), 6 middle (MLS), and 5 apical (ALS) segments and relative regional strain ratio [ALS/(BLS + MLS)] were also calculated. Ejection fraction and diastolic indices did not differ between the two groups. LV mass index was greater in AFD (P < 0.01). GLS (P = 0.006), BLS (P < 0.0001), and MLS (P = 0.003), but not ALS, were lower in AFD patients and relative regional strain ratio was higher in AFD (P < 0.01) than in controls. These analyses were confirmed separately in the two genders and even after excluding patients with wall hypertrophy. By subdividing AFD patients according to lysoGB3 levels, 9 patients with lysoGB3 ≥ 1.8 ng/L had lower ALS compared to 11 patients with lysoGB3 < 1.8 ng/L (P < 0.01).

CONCLUSION

In naïve AFD patients, we observed an early reduction of LV LS, involving mainly LV basal myocardial segments. Nevertheless, the association found between the higher lysoGB3 levels and the lower apical cap LS demonstrates that apical segments LS, despite still normal, is not spared at diagnosis.

Percentile curves for left ventricle structural, functional and haemodynamic parameters obtained in healthy children and adolescents from echocardiography-derived data

BACKGROUND

Transthoracic echocardiography is the most common non-invasive technique for the study of the left ventricle (LV) and the proximal aorta. Despite the clinical value, there is scarcity of data about reference intervals (RIs) and percentiles for thoracic aorta dimension and LV structural and functional parameters, obtained from population-based studies in children and adolescents. The aim was to generate RIs for LV, haemodynamic and thoracic aorta parameters obtained from transthoracic echocardiography in healthy children, adolescents and young adults from a South-American population.

METHODS

One thousand ninety-five healthy subjects (5-24 years) were studied (M-mode, B-mode and Doppler echocardiography).

RESULTS

RIs for LV structural (diameters, volumes and wall thickness) and functional (stroke volume, cardiac output, cardiac index, transmitral E and A flow waves velocities) parameters; systemic vascular resistance and aortic root diameter were obtained using parametric regression analyzes based on fractional polynomials. Covariate analysis (i.e., adjusting for age, body surface) showed that specific sex-specific RIs were necessary. Then, age, body height (BH), body weight (BW), body surface area (BSA), and sex-specific 1st, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th and 99th percentiles were obtained. Our results were in agreement with and complimentary to available international databases.

CONCLUSION

This study provides RIs for echocardiography-derived haemodynamic, LV (structural and functional) and aortic parameters in children, adolescents and young adults considering data obtained from the largest Argentinean database. In early stages of life an adequate interpretation of echocardiography-derived LV and aortic parameters requires considering age, BH, BW, BSA and/or sex-specific RIs.

Sex-specific echocardiographic reference values: the women's point of view

: Clinical presentation, diagnosis and outcomes of cardiac diseases are influenced by the activity of sex steroid hormones. These hormonal differences explain the later development of heart diseases in women in comparison with men and the different clinical picture, management and prognosis. Echocardiography is a noninvasive and easily available technique for the analysis of cardiac structure and function. The aim of the present review is to underline the most important echocardiographic differences between sexes. Several echocardiographic studies have found differences in healthy populations between women and men. Sex-specific difference of some of these parameters, such as left ventricular (LV) linear dimensions and left atrial volume, can be explained on the grounds of smaller body size of women, but other parameters (LV volumes, stroke volume and ejection fraction, right ventricular size and systolic function) are specifically lower in women, even after adjusting for body size and age. Sex-specific differences of standard Doppler and Tissue Doppler diastolic indices remain controversial, but it is likely for aging to affect LV diastolic function more in women than in men. Global longitudinal strain appears to be higher in women during the childbearing age - a finding that also highlights a possible hormonal influence in women. All these findings have practical implications, and sex-specific reference values are necessary for the majority of echocardiographic parameters in order to distinguish normalcy from disease. Careful attention on specific cut-off points in women could avoid misinterpretation, inappropriate management and delayed treatment of cardiac diseases such as valvular disease and heart failure.

Arterial hypertension and atrial fibrillation: standard and advanced echocardiography from diagnosis to prognostication

: Structural changes in left and right cardiac chambers that occur in arterial hypertension (AH) may lead to an increased risk of atrial fibrillation. Considering that AH is currently the most common cardiovascular disease in the general population, it represents a major risk factor for atrial fibrillation development. This review explores the complex relationship between atrial fibrillation and AH, starting from its pathophysiological basis. It focuses on the role of echocardiography in the management of hypertensive and atrial fibrillation patients, with emphasis on what should be evaluated about left ventricular remodeling, diastolic and systolic function, left atrial (LA) size and function and right ventricular deformation in patients with AH.

Allometric Relationships for Cardiac Size and Longitudinal Function in Healthy Chinese Adults - Normal Ranges and Clinical Correlates

BACKGROUND

Cardiac size measurements require indexing to body size. Allometric indexing has been investigated in Caucasian populations but a range of different values for the so-called allometric power exponent (b) have been proposed, with uncertainty as to whether allometry offers clinical utility above body surface area (BSA)-based indexing. We derived optimal values for b in normal echocardiograms and validated them externally in cardiac patients.

METHODS AND RESULTS

Values for b were derived in healthy adult Chinese males (n=1,541), with optimal b for left ventricular mass (LVM) of 1.66 (95% confidence interval 1.41-1.92). LV hypertrophy (LVH) defined as indexed LVM >75 g/m^1.66 was associated with adverse outcomes in an external validation cohort (n=738) of patients with acute coronary syndrome (odds ratio for reinfarction: 2.4 (1.1-5.4)). In contrast, LVH defined by BSA-based indexing or allometry using exponent 2.7 exhibited no significant association with outcomes (P=NS for both). Cardiac longitudinal function also varied with body size: septal and RV free wall s', TAPSE and lateral e' all scaled allometrically (b=0.3-0.9).

CONCLUSIONS

An optimal b of 1.66 for LVM in healthy Chinese was found to validate well, with superior clinical utility both to that of BSA-based indexing and to b=2.7. The effect of allometric indexing of cardiac function requires further study.

Z-score of Mitral Annular Plane Systolic Excursion is a Useful Indicator of Evaluation of Left Ventricular Function in Patients with Acute-Phase Kawasaki Disease

We previously reported the clinical usefulness of the mitral annular plane systolic excursion (MAPSE) to evaluate the left ventricular (LV) function in patients with Kawasaki disease (KD) in the acute-phase. However, the feasibility of the MAPSE z-score has not been evaluated in patients with acute KD. We prospectively studied 60 KD patients without coronary aneurysms. The MAPSE z-scores were calculated using our standard MAPSE data. Brain natriuretic peptide (BNP) was measured as a parameter of LV function. In total, 281 healthy age- and body size-matched subjects were chosen as the control group. The MAPSE z-score decreased in the acute-phase (median value, -1.4) and increased in the convalescent phase (median value, 0.18; P < 0.0001). However, there was no significant difference in the MAPSE z-score between patients in the convalescent phase and the control patients (0.18 vs. 0.02, P = 0.199). Multivariate regression analysis revealed that BNP was an independent predictor of the MAPSE z-score (β = 0.40, P < 0.005). According to the receiver operating characteristic (ROC) analysis, the optimal cutoff value for the MAPSE z-score to judge LV dysfunction was -0.9. The MAPSE z-score is a useful index to evaluate LV function, and the cutoff value of -0.9 can be an indicator to judge LV dysfunction in the patients with acute-phase KD.

The Prevalence of Left Ventricular Hypertrophy in Obese Children Varies Depending on the Method Utilized to Determine Left Ventricular Mass

Obesity and left ventricular hypertrophy (LVH) have been identified as independent risk factors for cardiovascular events. The definition of LVH depends on the geometric algorithm used to calculate LV mass (LVM) by echocardiography and the method used to normalize LVM for body size. This study evaluates the effect of these methods on the prevalence of LVH in obese children. LVM for 109 obese and 109 age-matched non-obese children was calculated using M-mode or two-dimensional echocardiography (2DE). LVM was then normalized to height 2.7 as indexed LVM (LVMI), to body surface area (BSA), height, and lean body mass (LBM) as LVM Z-scores. LVH was defined as LVMI >95th ‰ using age-specific normal reference values or LVM Z-scores ≥2. The prevalence of LVH by LVMI and LVM Z-scores was compared. There was a correlation between LVM determined by M-mode and by 2DE (R (2) = 0.91), although M-mode LVM was greater than 2DE LVM. However, the difference between these values was greater in obese children than in non-obese children. Based on the method of normalization, the prevalence of LVH among obese children was 64 % using LVMI, 15 % using LVM Z-scores for height, 8 % using LVM Z-scores for BSA and 1 % using LVM Z-scores for LBM. Height-based normalization correlates with obesity and hypertension. The methods used to measure and normalize LVM have a profound influence on the diagnosis of LVH in obese children. Further study is needed to determine which method identifies children at risk for cardiovascular morbidity and mortality.

Right to Left Ventricular Diameter Ratio ≥0.42 is the Warning Flag for Suspecting Atrial Septal Defect in Preschool Children: Age- and Body Surface Area-Related Reference Values Determined by M-Mode Echocardiography

It is not always easy to observe and screen atrial septal defects (ASD) using echocardiography. In addition, there are no established echocardiographic reference indices for screening patients with ASDs. We retrospectively reviewed our database and recruited 151 isolated ASD patients and 2769 healthy subjects. In total, 307 echocardiographic studies were performed for ASD patients. Surgical repairs were done in 75 of the ASD patients. The ratio of right to left ventricular end-diastolic dimensions (RVD/LVD), which was determined by M-mode echocardiography, was used as an index of RV dilatation. After obtaining age- and body surface area (BSA)-related RVD/LVD nomograms in healthy subjects, we calculated the z-scores of RVD/LVD for all subjects and obtained the optimal cut-off values to differentiate patients with ASD from healthy subjects. The optimal cut-off values were high in neonates and gradually decreased with an increase in the age and BSA, but were almost constant in children aged >4 years or whose BSA was >0.65 m(2). The cut-off values of RVD/LVD for suspected ASD were ≥0.42 in children aged >4 years or those whose BSA was >0.65 m(2). Those for an ASD operation were ≥0.46 in those whose BSA > 0.65 m(2). The RVD/LVD determined by M-mode echocardiography is a useful index to evaluate RV dilatation in patients with ASDs. The RVD/LVD ≥ 0.42 is the warning flag for suspecting ASD in preschool children and that ≥0.46 may be a clinical important sign to determine ASD operation.

Left Ventricular Mass Indexing in Infants, Children, and Adolescents: A Simplified Approach for the Identification of Left Ventricular Hypertrophy in Clinical Practice

OBJECTIVE

To determine a simplified method to identify presence of left ventricular hypertrophy (LVH) in pediatric populations because the relationship between heart growth and body growth in children has made indexing difficult for younger ages.

STUDY DESIGN

Healthy children (n = 400; 52% boys, 0-18 years of age) from 2 different European hospitals were studied to derive a simplified formula. Left ventricular mass (LVM) was calculated according to the Devereux formula. The derived approach to index LVM was tested on a validation cohort of 130 healthy children from a different hospital center.

RESULTS

There was a strong nonlinear correlation between height and LVM. LVM was best related to height to a power of 2.16 with a correction factor of 0.09. Analysis of residuals for LVM/[(height(2.16)) + 0.09] showed an homoscedastic distribution in both sexes throughout the entire height range. A partition value of 45 g/m(2.16) was defined as the upper normal limit for LVM index. As opposed to formula suggested by current guidelines (ie, LVM/height(2.7)) when applying the proposed approach in the validation cohort of 130 healthy participants, no false positives for LVH were found (0% vs 8%; P < .01).

CONCLUSIONS

Our data support the possibility to have a single partition (ie, 45 g/m(2.16)) value across the whole pediatric age range to identify LVH, without the time-consuming need of computing specific percentiles for height and sex.

New Reference Centiles for Left Ventricular Mass Relative to Lean Body Mass in Children

BACKGROUND

Echocardiographic measurement of left ventricular (LV) mass is routinely performed in pediatric patients with elevated cardiovascular risk. The complex relationship between heart growth and body growth in children requires normalization of LV mass to determine its appropriateness relative to body size. LV mass is strongly determined by lean body mass (LBM). Using new LBM predictive equations, the investigators generated sex-specific LV mass-for-LBM centile curves for children 5 to 18 years of age.

METHODS

This retrospective study used M-mode echocardiographic data collected from 1995 through 2003 from 939 boys and 771 girls between 5 and 18 years of age (body mass index < 85th percentile for sex and age) to create smoothed sex-specific LV mass-for-LBM reference centile curves using the Lamda Mu Sigma method. The newly developed reference centiles were applied to children with essential hypertension and with chronic kidney disease, groups known to be at high risk for LV hypertrophy (LVH). The identification of LVH using two different normalization approaches was compared: LV mass-for-LBM and LV mass index-for-age percentiles.

RESULTS

Among 231 children at risk for LVH, on average, relative LV mass was higher using the LV mass index-for-age percentile method than the LV mass-for-LBM percentile method. LVH was more likely to be diagnosed among overweight children and less likely among thin children.

CONCLUSIONS

This study provides new LV mass reference centiles expressing LV mass relative to LBM, the strongest determinant of LV mass. These reference centiles may allow more accurate stratification of cardiovascular risk in children.

Canine fetal echocardiography: correlations for the analysis of cardiac dimensions

The aim of this study was to develop regression models for correlation of canine fetal heart development with body size to characterize normal development or suggest cardiac anomalies. Twenty clinically healthy pregnant bitches, either brachycephalic and non-brachycephalic, were examined ultrasonographically. Transabdominal fetal echocardiography was conducted every 4 days from the beginning of cardiac chambers differentiation until parturition. Ten cardiac parameters were measured: length, width and diameter of the heart; heart area; left and right ventricular dimensions; left and right atrial dimensions; and aortic and pulmonary artery diameter. Femoral length, biparietal diameter and abdominal cross-sectional area were also recorded. Regression equations were developed for each parameter of fetal body size, and linear and logarithmic models were compared. The model with the highest correlation coefficient was chosen to produce equations to calculate relative dimensions based on the correlations. Only the left-ventricular chamber differed between the two racial groups. Biparietal diameter was the independent parameter that produced the highest correlation coefficient for the most fetal cardiac dimensions, although good correlations were also observed using femoral length and abdominal cross-sectional area. Heart width and heart diameter were used as surrogates of cardiac development, as these measurements showed the best statistical correlation. Quantitative evaluation of fetal cardiac structures can be used to monitor normal and abnormal cardiac development.