Timothy J. Sekarski

Alterations in Ventricular Structure and Function in Obese Adolescents with Nonalcoholic Fatty Liver Disease

OBJECTIVE To determine the association among nonalcoholic fatty liver disease (NAFLD), metabolic function, and cardiac function in obese adolescents. STUDY DESIGN Intrahepatic triglyceride (IHTG) content (magnetic resonance spectroscopy), insulin sensitivity and β-cell function (5-hour oral glucose tolerance test with mathematical modeling), and left ventricular function (speckle tracking echocardiography) were determined in 3 groups of age, sex, and Tanner matched adolescents: (1) lean (n=14, body mass index [BMI]=20±2 kg/m2); (2) obese with normal (2.5%) IHTG content (n=15, BMI=35±3 kg/m2); and (3) obese with increased (8.7%) IHTG content (n=15, BMI=37±6 kg/m2). RESULTS The disposition index (β-cell function) and insulin sensitivity index were ∼45% and ∼70% lower, respectively, and whole body insulin resistance, calculated by homeostasis model of assessment-insulin resistance (HOMA-IR), was ∼60% greater, in obese than in lean subjects, and ∼30% and ∼50% lower and ∼150% greater, respectively, in obese subjects with NAFLD than those without NAFLD (P<.05 for all). Left ventricular global longitudinal systolic strain and early diastolic strain rates were significantly decreased in obese than in lean subjects, and in obese subjects with NAFLD than those without NAFLD (P<.05 for all), and were independently associated with HOMA-IR (β=0.634). IHTG content was the only significant independent determinant of insulin sensitivity index (β=-0.770), disposition index (β=-0.651), and HOMA-IR (β=0.738). CONCLUSIONS These findings demonstrate that the presence of NAFLD in otherwise asymptomatic obese adolescents is an early marker of cardiac dysfunction.

Feasibility and Reproducibility of Systolic Right Ventricular Strain Measurement by Speckle Tracking Echocardiography in premature infants

BACKGROUND Right ventricular (RV) systolic function is an important prognostic determinant of cardiopulmonary pathologies in premature infants. Measurements of dominant RV longitudinal deformation are likely to provide a sensitive measure of RV function. An approach for image acquisition and postacquisition processing is needed for reliable and reproducible measurements of myocardial deformation by two-dimensional (2D) speckle-tracking echocardiography. The aims of this study were to determine the feasibility and reproducibility of 2D speckle-tracking echocardiographic measurement of RV peak global longitudinal strain (pGLS) and peak global longitudinal strain rate in premature infants and to establish methods for acquiring and analyzing strain. METHODS The study was designed in two phases: (1) a training phase to develop methods of image acquisition and postprocessing in a cohort of 30 premature infants (born at 28 ± 1 weeks) and (2) a study phase to prospectively test in a separate cohort of 50 premature infants (born at 27 ± 1 weeks) if the methods improved the feasibility and reproducibility of RV pGLS and peak global longitudinal strain rate measurements to a clinically significant level, assessed using Bland-Altman analysis (bias, limits of agreement, coefficient of variation, and intraclass correlation coefficient). RESULTS Strain imaging was feasible from 84% of the acquisitions using the methods developed for optimal speckle brightness and frame rate for RV-focused image acquisition. There was high intraobserver (bias, 3%; 95% limits of agreement, -1.6 to +1.6; coefficient of variation, 2.7%; intraclass correlation coefficient, 0.97; P = .02) and interobserver (bias, 7%; 95% limits of agreement, -4.8 to +4.73; coefficient of variation, 3.9%; intraclass correlation coefficient, 0.93; P < .05) reproducibility, with excellent linear correlation between the two pGLS measurements (r = 0.97 [P < .01] and r = 0.93 [P < .05], respectively). CONCLUSIONS This study demonstrates high clinical feasibility and reproducibility of RV pGLS and RV peak global longitudinal strain rate measurements by 2D speckle-tracking echocardiography in premature infants and offers methods for image acquisition and data analysis for systolic strain imaging that can provide a reliable assessment of global RV function.

Effects of Frame Rate on Two-Dimensional Speckle Tracking–Derived Measurements of Myocardial Deformation in Premature Infants

Frame rate (FR) of image acquisition is an important determinant of the reliability of 2‐dimensional speckle tracking echocardiography (2DSTE)‐derived myocardial strain. Premature infants have relatively high heart rates (HR). The aim was to analyze the effects of varying FR on the reproducibility of 2DSTE‐derived right ventricle (RV) and left ventricle (LV) longitudinal strain (LS) and strain rate (LSR) in premature infants.

CARDIAC DYSFUNCTION IS ASSOCIATED WITH INSULIN RESISTANCE IN OBESE ADOLESCENTS

One third of adolescents are obese in the United States. Half of them have insulin resistance (IR). Animal and human adult studies suggest that IR is associated with alterations in myocardial substrate metabolism and efficiency that lead to cardiac dysfunction. We hypothesize that in obese

PULMONARY ARTERY ACCELERATION TIME, AN ACCURATE NON-INVASIVE MEASURE OF PULMONARY HEMODYNAMICS IN CHILDREN

The standard method for pulmonary hemodynamic evaluation in children is by right-heart catheterization (RHC). However, the invasive nature of RHC is not applicable for everyday use in clinical practice in children. Doppler echocardiography (DE) derived Pulmonary Artery Acceleration Time (PAAT) is a

EFFECTS OF FRAME RATE ON TWO-DIMENSIONAL SPECKLE-TRACKING-DERIVED MEASUREMENTS OF MYOCARDIAL DEFORMATION IN PREMATURE INFANTS

Frame rate (FR) of image acquisition is an important determinant of the reliability of 2D speckle tracking echocardiography (2DSTE)-derived myocardial strain. Premature infants have relatively high heart rates (HR). Our objective was to analyze the effects of varying FR on the reproducibility of

NOVEL ECHOCARDIOGRAPHIC ASSESSMENT OF RIGHT VENTRICULAR FUNCTION IN PRETERM INFANTS: FEASIBILITY AND REPRODUCIBILITY OF RIGHT VENTRICULAR STRAIN MEASUREMENTS BY SPECKLE-TRACKING ECHOCARDIOGRAPHY

The right ventricular (RV) function is an important determinant of hemodynamic status and prognosis of cardiopulmonary pathologies in neonates. However, RV geometry does not lend itself to conventional assessment of ventricular function. Strain and strain rate represent sensitive measures of

DOPPLER ECHOCARDIOGRAPHY INACCURATELY ESTIMATES RIGHT VENTRICULAR PRESSURE IN CHILDREN WITH ELEVATED RIGHT HEART PRESSURE

Doppler echocardiography (DE) is widely used as a surrogate for right heart catheterization (RHC), the gold standard, to assess and monitor elevated right heart pressure in children. However, its accuracy has not been validated in children. Simultaneous pressure gradients between right ventricle