Guidelines for Performing a Comprehensive Pediatric Transthoracic Echocardiogram: Recommendations From the American Society of Echocardiography.

Echocardiography is a fundamental component of pediatric cardiology, and appropriate indications have been established for its use in the setting of suspected, congenital, or acquired heart disease in children. Since the publication of guidelines for pediatric transthoracic echocardiography in 2006 and 2010, advances in knowledge and technology have expanded the scope of practice beyond the use of traditional modalities such as two-dimensional, M-mode, and Doppler echocardiography to evaluate the cardiac segmental structures and their function. Adjunct modalities such as contrast, three-dimensional, and speckle-tracking echocardiography are now used routinely at many pediatric centers. Guidelines and recommendations for the use of traditional and newer adjunct modalities in children are described in detail in this document. In addition, suggested protocols related to standard operations, infection control, sedation, and quality assurance and improvement are included to provide an organizational structure for centers performing pediatric transthoracic echocardiograms.

Adverse remodelling in tetralogy of Fallot: From risk factors to imaging analysis and future perspectives.

Although contemporary outcomes of initial surgical repair of tetralogy of Fallot (TOF) are excellent, the survival of adult patients remains significantly lower than that of the normal population due to the high incidence of heart failure, ventricular arrhythmias, and sudden cardiac death. The underlying mechanisms are only partially understood but involve an adverse biventricular response, so-called remodelling, to key stressors such as right ventricular (RV) pressure-and/or volume-overload, myocardial fibrosis, and electro-mechanical dyssynchrony. In this review, we explore risk factors and mechanisms of biventricular remodelling, from histological to electro-mechanical aspects, and the role of imaging in their assessment. We discuss unsolved challenges and future directions to better understand and treat the long-term sequelae of this complex congenital heart disease.

Left ventricular remodelling in rheumatic heart disease - trends over time and implications for follow-up in childhood.

BACKGROUND: Rheumatic heart disease (RHD) is the most common form of acquired heart disease worldwide. In RHD, volume loading from mitral regurgitation leads to left ventricular (LV) dilatation, increased wall stress, and ultimately LV dysfunction. Improved understanding of LV dynamics may contribute to refined timing of intervention. We aimed to characterize and compare left ventricular remodelling between rheumatic heart disease (RHD) severity groups by way of serial echocardiographic assessment of volumes and function in children. METHODS: Children with RHD referred to Perth Children's Hospital (formally Princess Margaret Hospital) (1987-2020) were reviewed. Patients with longitudinal pre-operative echocardiograms at diagnosis, approximately 12 months and at most recent follow-up, were included and stratified into RHD severity groups. Left ventricular (LV) echocardiographic parameters were assessed. Adjusted linear mixed effect models were used to compare interval changes. RESULTS: 146 patients (median age 10 years, IQR 6-14 years) with available longitudinal echocardiograms were analysed. Eighty-five (58.2%) patients had mild, 33 (22.6%) moderate and 28 (19.2%) severe RHD at diagnosis. Mean duration of follow-up was 4.6 years from the initial diagnosis. Severe RHD patients had significantly increased end-systolic volumes (ESV) and end-diastolic volumes (EDV) compared to mild/moderate groups at diagnosis (severe versus mild EDV mean difference 27.05 ml/m2, p < 0.001, severe versus moderate EDV mean difference 14.95 ml/m2, p = 0.006). Mild and moderate groups experienced no significant progression of changes in volume measures. In severe RHD, LV dilatation worsened over time. All groups had preserved cardiac function. CONCLUSIONS: In mild and moderate RHD, the lack of progression of valvular regurgitation and ventricular dimensions suggest a stable longer-term course. Significant LV remodelling occurred at baseline in severe RHD with progression of LV dilatation over time. LV function was preserved across all groups. Our findings may guide clinicians in deciding the frequency and timing of follow-up and may be of clinical utility during further reiterations of the Australia and New Zealand RHD Guidelines.

Diastolic myocardial mechanics and their relation to ventricular filling pressures and postoperative course in functionally single ventricles.

Diastolic dysfunction affects clinical outcomes in patients with a functionally single ventricle (FSV). The objective of this work is to study the association of ventricular mechanics and interventricular dependence on diastolic parameters and early post-Fontan outcomes. Sixty-one patients with FSV underwent echocardiography, cardiac catheterization, and magnetic resonance imaging on the same day before or after the Fontan procedure. Echocardiographic diastolic parameters, ventricular mass, and incoordinate wall motion, defined by the number of dyskinetic segments or by the lateral wall delay, were determined and studied for relationships with invasively measured hemodynamics and early postoperative Fontan course. In subjects with a sizable secondary ventricle, incoordinate motion was additionally analyzed at the left- and right-sided ventricular free walls. Resting ventricular end-diastolic pressure (VEDP) was ≤10 mmHg in most subjects. Individual echocardiographic parameters of the diastolic flow and tissue velocities did not correlate with VEDP, other hemodynamics, or post-Fontan clinical course. Incoordinate wall motion in the dominant and in the sizeable secondary ventricle, defined by the lateral wall delay or by the number of dyskinetic segments, was the only echo parameter that correlated, albeit weakly, with VEDP (r = 0.247, P = 0.040), oxygen saturation (r = -0.417, P = 0.001), pulmonary vascular resistance and flow (Qp) (r = -0.303, P = 0.011), Fontan fenestration flow (r = 0.512, P = 0.009), and duration of endotracheal intubation (r = 0.292, P = 0.022). When the nondominant (secondary) ventricle was accounted for in the analysis of incoordinate wall motion, these associations strengthened. The degree of incoordinate ventricular wall motion in diastole was associated with VEDP and postoperative Fontan course in FSV. Analysis of incoordinate wall motion of the dominant and sizeable secondary ventricle may be warranted and should be included in the assessment of the FSV after the Fontan procedure.NEW & NOTEWORTHY Diastolic dysfunction affects outcomes in patients with functionally single ventricles (FSVs) but is difficult to assess. We found that incoordinate wall motion was the only echo parameter that correlated with FSV end-diastolic pressure, oxygen saturation, pulmonary vascular resistance and flow, and duration of endotracheal intubation. Analysis of incoordinate wall motion in the nondominant (secondary) ventricle strengthened these associations. Analyzing incoordinate wall motion should be included in the assessment of the FSV after the Fontan procedure.

Electromechanical Dyssynchrony Is Associated With Right Ventricular Remodeling and Dysfunction Independently of Pulmonary Regurgitation Late After Tetralogy of Fallot Repair.

BACKGROUND: The aim of this study was to investigate the relationship among right ventricular (RV) dilatation, dysfunction, and electromechanical dyssynchrony (EMD) in patients with repaired tetralogy of Fallot (rTOF). METHODS: Data from a prospective rTOF registry of subjects with moderate or greater pulmonary regurgitation (PR) and contemporary imaging were analyzed. Electrocardiograms and echocardiograms were analyzed for EMD (prolonged QRS duration [QRSd], echocardiographic septal flash, and mechanical delay) and mechanical dispersion. The relationship among these, RV measurements on cardiac magnetic resonance, exercise capacity, and incident arrhythmia or death was analyzed with adjustment for PR. RESULTS: In total, 271 patients with rTOF (42% women; median age, 32 years; interquartile range [IQR], 23-34 years) were included. Patients had moderate to severe PR (median PR fraction, 38%; IQR, 30%-47%), moderate to severe RV enlargement (median RV end-diastolic volume index, 161 mL/m2; IQR, 138-186 mL/m2) and mild RV systolic dysfunction (median RV ejection fraction [RVEF], 44%; IQR, 38%-48%). Eleven patients (4%) experienced ventricular arrhythmia or death. Presence of EMD was associated with larger RV size (RV end-diastolic volume index and RV end-systolic volume index, P = .006 and P < .001, respectively) and lower RVEF (P < .001). A sharp inflection in the relation among QRSd, RV size, and RVEF was observed when QRSd exceeded 150 msec (3.1% decrease in RVEF for every 20-msec increase in QRSd between 160 and 200 msec). Similar inflection points were observed for the mechanical delay between the RV basal-lateral and midseptal segments. The mechanical delay was higher in patients with vs without incident atrial arrhythmia (371 vs 276 msec, P = .014). CONCLUSIONS: In adults with rTOF, EMD is independently associated with larger RV size, lower RVEF, and incident atrial arrhythmias.

Multimodality Imaging of Right Heart Function: JACC Scientific Statement.

Right ventricular (RV) size and function assessed by multimodality imaging are associated with outcomes in a variety of cardiovascular diseases. Understanding RV anatomy and physiology is essential in appreciating the strengths and weaknesses of current imaging methods and gives these measurements greater context. The adaptation of the right ventricle to different types and severity of stress, particularly over time, is specific to the cardiovascular disease process. Multimodality imaging parameters, which determine outcomes, reflect the ability to image the initial and longitudinal RV response to stress. This paper will review the standard and novel imaging methods for assessing RV function and the impact of these parameters on outcomes in specific disease states.

Longitudinal Changes in Ventricular Mechanics in Adolescents After the Fontan Operation.

BACKGROUND: Ventricular dysfunction is a significant clinical challenge in the long-term follow-up of patients with single-ventricle (SV) physiology. Ventricular function and myocardial mechanics can be studied using speckle-tracking echocardiography, which provides information on myocardial deformation. Limited information is available on serial changes in SV myocardial mechanics after the Fontan operation. The aim of this study was to describe serial changes in myocardial mechanics in children after the Fontan operation and the relationship of these changes with myocardial fibrosis markers as obtained by cardiac magnetic resonance and exercise performance parameters. METHODS: The authors hypothesized that ventricular mechanics decline in patients with SVs over time and are associated with increased myocardial fibrosis and reduced exercise performance. A single-center retrospective cohort study including adolescents after the Fontan operation was conducted. Ventricular strain and torsion were assessed using speckle-tracking echocardiography. Cardiac magnetic resonance and cardiopulmonary exercise testing data closest to the latest echocardiographic examinations were performed. The most recent follow-up echocardiographic and cardiac magnetic resonance data were compared with those from sex- and age-matched control subjects and with individual patients' early post-Fontan data. RESULTS: Fifty patients with SVs (31 left ventricle, 13 right ventricle [RV], and six codominant) were included. Median time at follow-up echocardiography from the time of Fontan was 12.8 years (interquartile range [IQR], 10.6 to 16.6 years). Compared with early post-Fontan echocardiography, follow-up assessment showed reduced global longitudinal strain (-17.5% [IQR, -14.5% to -19.5%] vs -19.8% [IQR, -16.0% to -21.7%], P = .01], circumferential strain (-15.7% [IQR, -11.4% to -18.7%] vs -18.9% [IQR, -15.2% to -25.0%], P = .009), and torsion (1.28°/cm [IQR, 0.51°/cm to 1.74°/cm] vs 1.72°/cm [IQR, 0.92°/cm to 2.34°/cm], P = .02), with decreased apical rotation but no significant change in basal rotation. Single RVs had lower torsion compared with single left ventricles (1.04°/cm [IQR, 0.12°/cm to 2.20°/cm] vs 1.25°/cm [IQR, 0.25°/cm to 2.51°/cm], P = .01). T1 values were higher in patients with SV compared with control subjects (1,009 ± 36 vs 958 ± 40 msec, P = .004) and in those with single RVs compared with single left ventricles (1,023 ± 19 vs 1,006 ± 17 msec, P = .02). T1 was correlated with circumferential strain (r = 0.59, P = .04) and inversely correlated with O2 saturation (r = -0.67, P < .001) and torsion (r = -0.71, P = .02). Peak oxygen consumption was correlated with torsion (r = 0.52, P = .001) and untwist rates (r = 0.23, P = .03). CONCLUSIONS: After the Fontan procedures, there is a progressive decrease in myocardial deformation parameters. The progressive decrease in SV torsion is related to a decrease in apical rotation, which is more pronounced in single RVs. Decreased torsion is associated with increased markers of myocardial fibrosis and lower maximal exercise capacity. Torsional mechanics may be an important parameter to monitor after Fontan palliation, but further prognostic information is required.

The use of 2-D speckle tracking echocardiography in differentiating healthy adolescent athletes with right ventricular outflow tract dilation from patients with arrhythmogenic cardiomyopathy.

AIMS: Echocardiographic assessment of adolescent athletes for arrhythmogenic cardiomyopathy (ACM) can be challenging owing to right ventricular (RV) exercise-related remodelling, particularly RV outflow tract (RVOT) dilation. The aim of this study is to evaluate the role of RV 2-D speckle tracking echocardiography (STE) in comparing healthy adolescent athletes with and without RVOT dilation to patients with ACM. METHODS AND RESULTS: A total of 391 adolescent athletes, mean age 14.5 ± 1.7 years, evaluated at three sports academies between 2014 and 2019 were included, and compared to previously reported ACM patients (n = 38 definite and n = 39 borderline). Peak systolic RV free wall (RVFW-Sl), global and segmental strain (Sl), and corresponding strain rates (SRl) were calculated. The participants meeting the major modified Task Force Criteria (mTFC) for RVOT dilation were defined as mTFC+ (n = 58, 14.8%), and the rest as mTFC- (n = 333, 85.2%). Mean RVFW-Sl was -27.6 ± 3.4% overall, -28.2 ± 4.1% in the mTFC+ group and - 27.5 ± 3.3% in the mTFC- group. mTFC+ athletes had normal RV-FW-Sl when compared to definite (-29% vs -19%, p < 0.001) and borderline ACM (-29% vs -21%, p < 0.001) cohorts. In addition, all mean global and regional Sl and SRl values were no worse in the mTFC+ group compared to the mTFC- (p values range < 0.0001 to 0.1, inferiority margin of 2% and 0.1 s-1 respectively). CONCLUSIONS: In athletes with RVOT dilation meeting the major mTFC, STE evaluation of the RV can demostrate normal function and differentiate physiological remodelling from pathological changes found in ACM, improving screening in grey-area cases.

Impact of Ventricular Geometric Characteristics on Myocardial Stiffness Assessment Using Shear-Wave Velocity in Healthy Children and Young Adults.

BACKGROUND: Diastolic myocardial stiffness (MS) can serve as a key diagnostic parameter for congenital or acquired heart diseases. Using shear modulus and shear-wave velocity (SWV), shear-wave elastography (SWE) is an emerging ultrasound-based technique that can allow noninvasive assessment of MS. However, MS extrinsic parameters such as left ventricular geometric characteristics could affect shear-wave propagation. The aims of this study were to determine a range of normal values of MS using SWE in age groups of healthy children and young adults and to explore the impact of left ventricular geometric characteristics on SWE. METHODS: Sixty healthy volunteers were recruited in the study and divided into 2 groups: neonates (0-1 months old, n = 15) and >1 month old (1 month to 45 years of age, n = 45). SWE was performed using the Verasonics Vantage systems with a phased-array ultrasound probe. The anteroseptal basal segment was assessed in two views. SWE was electrocardiographically triggered during the end-diastolic phase. Conventional echocardiography was performed to assess ventricular function and anatomy. Results are presented as stiffness values along with mean velocity measurements and SDs. Simple and multivariate linear regression analyses were performed. RESULTS: For neonates, mean MS was 1.87 ± 0.79 kPa (range, 0.59-2.91 kPa; mean SWV, 1.37 ± 0.57 m/sec), with high variability and no correlation with age (P = .239). For this age group, no statistically significant correlation was found between MS and any demographic or echocardiographic parameters (P > .05). For the >1 month old group, a mean MS value of 1.67 ± 0.53 kPa was observed (range, 0.6-3 kPa; mean SWV, 1.29 ± 0.49 m/sec) for healthy volunteers. When paired for age, no sex-related difference was observed (P = .55). In univariate linear regression analysis, age (r = 0.83, P < .01), diastolic interventricular septal thickness (r = 0.72, P < .01), and left ventricular end-diastolic diameter (r = 0.67, P < .01) were the parameters with the highest correlation coefficients with MS. In a multiple linear regression analysis incorporating these three parameters as cofounding factors, age was the only statistically significant parameters (r = 0.81, P = .02). CONCLUSION: Diastolic MS increases linearly in children and young adults. Diastolic MS correlates more robustly with age than with myocardial and left ventricular geometric characteristics. However, the geometry affects SWV, implying the need to determine well-established boundaries in future studies for the clinical application of SWE.

Right Ventricular Electromechanical Dyssynchrony and Its Relation to Right Ventricular Remodeling, Dysfunction, and Exercise Capacity in Ebstein Anomaly.

BACKGROUND: Abnormal atrioventricular and intraventricular electrical conduction and dysfunction of the functional right ventricle (fRV) are common in Ebstein anomaly (EA). However, fRV mechanical dyssynchrony and its relation to fRV function are poorly characterized. We evaluated fRV mechanical dyssynchrony in EA patients in relation to fRV remodeling, dysfunction, and exercise intolerance. METHODS: We retrospectively analyzed data from nonoperated EA patients and age-matched controls who underwent echocardiography, cardiovascular magnetic resonance imaging, and cardiopulmonary exercise testing to quantify right ventricular (RV) remodeling, dysfunction, and exercise capacity. The relation of these to fRV dyssynchrony was retrospectively investigated. Right ventricular mechanical dyssynchrony was defined by early fRV septal activation (right-sided septal flash), RV lateral wall prestretch/late contraction, postsystolic shortening, and intra-RV delay using two-dimensional strain echocardiography. The SD of time to peak shortening among the fRV segments was calculated as a parameter of mechanical dispersion. RESULTS: Thirty-five EA patients (10 of whom were <18 years of age) and 35 age-matched controls were studied. Ebstein anomaly patients had worse RV function and increased intra-RV dyssynchrony versus controls. Nineteen of 35 (54%) EA patients had early septal activation with simultaneous stretch and consequent late activation and postsystolic shortening of RV lateral segments. Intra-fRV mechanical delay correlated with fRV end-diastolic volume index (r = 0.43, P < .05) and fRV end-systolic volume index (r = 0.63, P < .001). The fRV ejection fraction was lower in EA with versus without right-sided septal flash (44.9 ± 11.0 vs 54.2 ± 8.2, P = .012). The fRV mechanical dispersion correlated with the percentage of predicted peak VO2 (r = -0.35, P < .05). CONCLUSIONS: In EA, fRV mechanical dyssynchrony is associated with fRV remodeling, dysfunction, and impaired exercise capacity. Mechanical dyssynchrony as a therapeutic target in selected EA patients warrants further study.

Growth of unrepaired hypoplastic proximal aortic arch and reintervention rate after aortic coarctation repair.

BACKGROUND: Treatment of tubular hypoplasia of the aortic arch (THAA) associated with aortic coarctation (CoA) remains controversial. We aimed to evaluate growth of unrepaired hypoplastic proximal aortic arches (PAAs) after surgical repair for CoA. METHODS: Preoperative and follow-up echocardiographic images of 139 patients who underwent CoA repairs from 2005 to 2012 were reviewed. THAA was defined as PAA z-score <-3 and non-THAA group z-score ≥-3. Reintervention rates due to aortic obstruction were assessed using competing risk models and diameters of the aorta were compared with Mann-Whitney U tests. RESULTS: Fifty patients (36%) had THAA and 89 (64%) had non-THAA. The survival rate was 94% at 10 years. The overall reintervention rate at 10 years was 9% in the THAA group and 16% in the non-THAA group (P = .54). The catheter reintervention rate at ten years was 2% in the THAA group and 16% in the non-THAA group (P = .031). The surgical reintervention rate at ten years was 7% in the THAA group and 0% in the non-THAA group (P = .016). All 4 patients who required surgical reintervention were in the THAA group and 3 patients with PAA obstruction had preoperative PAA z-scores -3.6, -4.2, and -4.3. Follow-up echocardiograms showed PAA catch-up growth in the THAA group compared with the non-THAA group (preoperative z-score of -3.6 vs -2.3, and at 7 years of -1.1 vs -1.2; P < .001). CONCLUSIONS: Unrepaired PAA hypoplasia grows after CoA repair. Reintervention rates were comparable between groups but those with THAA had higher surgical reintervention rates.

Tetralogy of Fallot Across the Lifespan: A Focus on the Right Ventricle.

Tetralogy of Fallot is a cyanotic congenital heart disease, for which various surgical techniques allow patients to survive to adulthood. Currently, the natural history of corrected tetralogy of Fallot is underlined by progressive right ventricular (RV) failure due to pulmonic regurgitation and other residual lesions. The underlying cellular mechanisms that lead to RV failure from chronic volume overload are characterized by microvascular and mitochondrial dysfunction through various regulatory molecules. On a clinical level, these cardiac alterations are commonly manifested as exercise intolerance. The degree of exercise intolerance can be objectified and aid in prognostication through cardiopulmonary exercise testing. The timing for reintervention on residual lesions contributing to RV volume overload remains controversial; however, interval assessment of cardiac function and volumes by echocardiography and magnetic resonance imaging may be helpful. In patients who develop clinically important RV failure, clinicians should aim to maintain a euvolemic state through the use of diuretics while paying particular attention to preload and kidney function. In patients who develop signs of cardiogenic shock from right heart failure, stabilization through the use of inotropes and pressor is indicated. In special circumstances, the use of mechanical support may be appropriate. However, cardiologists should pay particular attention to residual lesions that may impact the efficacy of the selected device.

De nombreuses techniques chirurgicales permettent aux patients présentant une tétralogie de Fallot (TF), une forme de cardiopathie congénitale, de survivre jusqu'à l'âge adulte. À l'heure actuelle, l'évolution naturelle de la TF corrigée est caractérisée par une insuffisance ventriculaire droite (VD) progressive attribuable à une régurgitation pulmonaire et à d'autres lésions résiduelles. Les mécanismes cellulaires sous-jacents qui mènent à l'insuffisance VD due à une surcharge volumique chronique sont caractérisés par une dysfonction microvasculaire et mitochondriale faisant intervenir diverses molécules régulatrices. Sur le plan clinique, ces atteintes cardiaques se manifestent par une intolérance à l'effort qui peut être évaluée au moyen d'une épreuve d'effort cardiorespiratoire, ce qui permet de faciliter l'établissement d'un pronostic. Le moment propice pour une réintervention en cas de lésions résiduelles contribuant à la surcharge volumique du ventricule droit demeure controversé; toutefois, il peut être utile d'évaluer régulièrement la fonction et les volumes cardiaques au moyen d'une échocardiographie et de tests d'imagerie par résonance magnétique. En présence d'une insuffisance VD cliniquement importante, les cliniciens doivent tenter de maintenir les patients dans un état euvolémique en utilisant des diurétiques, tout en accordant une attention particulière à la précharge et à la fonction rénale. Si les patients manifestent des signes de choc cardiogénique associé à une insuffisance cardiaque droite, il convient de leur administrer des inotropes et des vasopresseurs pour stabiliser leur état. Dans certains cas, l'utilisation d'un dispositif d'assistance mécanique peut être appropriée. Cependant, les cardiologues doivent être attentifs aux lésions résiduelles, car elles peuvent influencer l'efficacité de ce dispositif.

Impact of mitral regurgitation on left ventricular remodeling and function in children with rheumatic heart disease.

The impact of mitral regurgitation (MR) from pediatric rheumatic heart disease (RHD) and its effect on left ventricular (LV) remodeling and function following surgical intervention is uncertain. The objective is to explore the impact of mitral valve (MV) surgeries on myocardial mechanics, remodeling and function and identify pre-operative predictors of post-operative dysfunction which may contribute to the optimal timing of intervention. A retrospective review of echocardiographic data was performed of eighteen pediatric patients with RHD (median 9yrs, IQR 6-12) who underwent MV surgery. Echocardiograms pre-operatively and a median of 13.5 months (IQR 10.2-15) following intervention were compared to controls. Pre-operative LV end-diastolic indexed volumes (LVEDVi) were significantly increased compared to controls and remained persistently larger post-operatively. LV ejection fraction (LVEF) (pre 62.6% ± 6.1, post 51.7% ± 9.7, p = 0.002), and global longitudinal strain (GLS) (pre - 24.3 ± 4.1, post - 18.2 ± 2.6, p < 0.001) decreased post-operatively at mid-term follow-up. Pre-operative LVEDVi was a significant predictor of post-operative LVEF, with a cut-off of ≥ 102 ml/m2 associated with LV dysfunction (LVEF < 55%; sensitivity 70%, specificity 75%). Pre-operative LVEDVi also negatively correlated with GLS (r = - 0.58, p = 0.01). LV dimensions and volumes remain persistently larger than controls while LV function decreases post-surgical alleviation of MR in paediatric RHD. Pre-operative LVEDVi predicted post-operative LV dysfunction and utilising LV indexed volumes in directing timing of surgical planning should be considered. Further studies are required to investigate whether timely alleviation of MR before significant LV dilatation and remodeling occur may substantially prevent LV dysfunction and improve outcomes.

The SGLT2i Dapagliflozin Reduces RV Mass Independent of Changes in RV Pressure Induced by Pulmonary Artery Banding.

BACKGROUND: Sodium glucose linked transporter 2 (SGLT2) inhibition not only reduces morbidity and mortality in patients with diagnosed heart failure but also prevents the development of heart failure hospitalization in those at risk. While studies to date have focused on the role of SGLT2 inhibition in left ventricular failure, whether this drug class is efficacious in the treatment and prevention of right heart failure has not been explored. HYPOTHESIS: We hypothesized that SGLT2 inhibition would reduce the structural, functional, and molecular responses to pressure overload of the right ventricle. METHODS: Thirteen-week-old Fischer F344 rats underwent pulmonary artery banding (PAB) or sham surgery prior to being randomized to receive either the SGLT2 inhibitor: dapagliflozin (0.5 mg/kg/day) or vehicle by oral gavage. After 6 weeks of treatment, animals underwent transthoracic echocardiography and invasive hemodynamic studies. Animals were then terminated, and their hearts harvested for structural and molecular analyses. RESULTS: PAB induced features consistent with a compensatory response to increased right ventricular (RV) afterload with elevated mass, end systolic pressure, collagen content, and alteration in calcium handling protein expression (all p < 0.05 when compared to sham + vehicle). Dapagliflozin reduced RV mass, including both wet and dry weight as well as normalizing the protein expression of SERCA 2A, phospho-AMPK and LC3I/II ratio expression (all p < 0.05). SIGNIFICANCE: Dapagliflozin reduces the structural, functional, and molecular manifestations of right ventricular pressure overload. Whether amelioration of these early changes in the RV may ultimately lead to a reduction in RV failure remains to be determined.

Nuclear Imaging in Pediatric Cardiology: Principles and Applications.

Nuclear imaging plays a unique role within diagnostic imaging since it focuses on cellular and molecular processes. Using different radiotracers and detection techniques such as the single photon emission scintigraphy or the positron emission tomography, specific parameters can be assessed: myocardial perfusion and viability, pulmonary perfusion, ventricular function, flow and shunt quantification, and detection of inflammatory processes. In pediatric and congenital cardiology, nuclear imaging can add complementary information compared to other imaging modalities such as echocardiography or magnetic resonance imaging. In this state-of-the-art paper, we appraise the different techniques in pediatric nuclear imaging, evaluate their advantages and disadvantages, and discuss the current clinical applications.

Reversal of right ventricular pressure loading improves biventricular function independent of fibrosis in a rabbit model of pulmonary artery banding.

Right ventricular (RV) pressure loading leads to RV and left ventricular (LV) dysfunction through RV hypertrophy, dilatation and fibrosis. Relief of RV pressure load improves RV function. However, the impact and mechanisms on biventricular reverse-remodelling and function are only partially characterized. We evaluated the impact of RV pressure overload relief on biventricular remodelling and function in a rabbit model of reversible pulmonary artery banding (PAB). Rabbits were randomized to three groups: (1) Sham-operated controls (n = 7); (2) PAB (NDef, n = 7); (3) PAB followed by band deflation (Def, n = 5). Sham and NDef animals were sacrificed at 6 weeks after PAB surgery. Def animals underwent PAB deflation at 6 weeks and sacrifice at 9 weeks. Biventricular geometry, function, haemodynamics, hypertrophy and fibrosis were compared between groups using echocardiography, magnetic resonance imaging, high-fidelity pressure-tipped catheters and histology. RV pressure loading caused RV dilatation, systolic dysfunction, myocyte hypertrophy and LV compression which improved after PAB deflation. RV end-diastolic pressure (RVEDP) decreased after PAB deflation, although remaining elevated vs. Sham. LV end-diastolic pressure (LVEDP) was unchanged following PAB deflation. RV and LV collagen volumes in the NDef and Def group were increased vs. Sham, whereas RV and LV collagen volumes were similar between NDef and Def groups. RV myocyte hypertrophy (r = 0.75, P < 0.001) but not collagen volume was related to RVEDP. LV myocyte hypertrophy (r = 0.58, P = 0.016) and collagen volume (r = 0.56, P = 0.031) correlated with LVEDP. In conclusion, relief of RV pressure overload improves RV and LV geometry, hypertrophy and function independent of fibrosis. The long-term implications of persistent fibrosis and increased biventricular filling pressures, even after pressure load relief, need further study. KEY POINTS: Right ventricular (RV) pressure loading in a pulmonary artery banding rabbit model is associated with RV dilatation, left ventricular (LV) compression; biventricular myocyte hypertrophy, fibrosis and dysfunction. The mechanisms and impact of RV pressure load relief on biventricular remodelling and function has not been extensively studied. Relief of RV pressure overload improves biventricular geometry in conjunction with improved RV myocyte hypertrophy and function independent of reduced fibrosis. These findings raise questions as to the importance of fibrosis as a therapeutic target.

Organization of Pediatric Echocardiography Laboratories: Impact of Sonographers on Clinical, Academic, and Financial Performance.

Echocardiography has evolved the first-line imaging for diagnosis and management of pediatric and congenital heart disease all over the world. While it recognized as essential component of pediatric cardiac care delivery, organization of pediatric echocardiography services is very heterogeneous across the world, mainly related to significant differences in material and human resources in heterogeneous health care systems. In this paper, we focus on the role of pediatric sonographers, defined as expert technicians in pediatric echocardiography. While in some services sonographers are an essential part of the organizational structure, other laboratories operate only with physicians trained in echocardiography. The impact of sonographers on clinical, academic and financial performance will be discussed. Two organizational models (with and without sonographers) will be compared, and the advantages and disadvantages of each model will be evaluated. Different models of care provision are possible and decisions on organizational models need to be adjusted to the demands and available resources.