Barbara Cifra

Stress echocardiography in paediatric cardiology

Stress echocardiography is a well-established technique in adult cardiology and is mainly used for assessing regional myocardial function in patients with known or suspected coronary artery disease (CAD). Apart from detecting ischaemia, stress echocardiography has found its place in the assessment of the haemodynamic significance of valve disease, particularly in selected patients with aortic stenosis and mitral regurgitation. Also in the paediatric population, stress imaging is most commonly used for the detection of ischaemia in patients with CADs such as post heart transplantation, Kawasaki Disease, and abnormal origin of coronary arteries. Other paediatric indications include the haemodynamic and myocardial response in patients with different types of congenital heart disease, the early detection of myocardial dysfunction in specific populations such as patients after anthracycline exposure, and the evaluation of pulmonary artery pressures and the right ventricular functional response. Techniques have evolved over time and in different paediatric echocardiographic laboratories, exercise stress echocardiography is replacing dobutamine stress echocardiography in older children. Moreover, integrating tissue Doppler and strain technology with stress imaging allows a more quantitative analysis of regional and global systolic and diastolic function. Current clinical applications mainly include patients after transplant, suspected CAD, and hypertrophic cardiomyopathy.

The role of echocardiography in Kawasaki disease

Kawasaki disease (KD) is an acute, self‐limited vasculitis affecting young children. It can result in coronary artery abnormalities in a significant proportion of patients, especially if the diagnosis is missed or treatment gets delayed. Echocardiography is the imaging modality of choice for detection of coronary artery abnormalities and assessment of myocardial function. It is also useful for characterization and risk stratification of patients with KD. Echocardiography should be performed at the time of diagnosis and then again at 1–2 weeks and 4–6 weeks after treatment, for uncomplicated cases who do not have significant coronary artery involvement. Use of a standardized imaging protocol is necessary to detect and characterize coronary artery abnormalities, including standardization of measurements (Z scores). For patients with evolving abnormalities, more frequent assessment is necessary in order to detect thromboses in aneurysms. Long‐term prognosis and management is dependent on both the maximal and current Z scores of aneurysms. Patients with large or giant aneurysms (i.e., Z score ≥ 10) are at the highest risk of both thrombosis and stenosis. Such patients need careful follow‐up for subsequent cardiovascular events. Many of them would be candidates for advanced cardiovascular imaging and may require revascularization therapy. Serial echocardiography plays a key role in surveillance. In addition, stress echocardiography has proven useful as a modality to assess for inducible myocardial ischemia. Intravascular ultrasound has been recommended for functional and structural assessment of coronary arteries in children with KD.

Ventricular Torsion in Young Patients With Single-Ventricle Anatomy

Background: In normal left ventricles, clockwise basal rotation and counterclockwise apical rotation result in systolic torsion. Torsion is important for contractile efficiency and may be especially important in single‐ventricle (SV) physiology. However, little is known about torsion in patients with SVs. The aim of this study was to measure torsion in SVs and to determine its relationship with other measures of ventricular function. The hypothesis was that torsion would be decreased in all SVs, most significantly in single right ventricles, and that it would correlate with other measures of ventricular function. Methods: A prospective cross‐sectional study was performed in 61 patients with SVs undergoing pre‐ or post‐Fontan cardiac catheterization and 30 matched control subjects. Echocardiography, catheterization, and cardiac magnetic resonance imaging were performed under the same anesthetic. Torsion and strain were measured using speckle‐tracking echocardiography. Intracardiac pressures, pulmonary vascular resistance, and cardiac magnetic resonance imaging–derived ventricular volume and ejection fraction were measured. Results: Thirty‐five patients were left ventricular dominant, 15 were right ventricular dominant, 10 were codominant, and one had indeterminate morphology. Thirty‐seven patients were pre‐Fontan and 24 were post‐Fontan. Patients with SVs had similar overall torsion as control subjects (median, 1.7°/cm vs 1.65°/cm; P = NS); however, they had decreased or reversed basal rotation (−0.32°/cm vs −0.93°/cm, P < .0001) and increased apical rotation (1.45°/cm vs 1.06°/cm, P = .0065). There were no differences on the basis of ventricular dominance or palliative stage. Torsion did not significantly correlate with other echocardiographic, catheter‐based, or cardiac magnetic resonance imaging measures of cardiac function. Conclusions: Single left and right ventricles exhibit preserved torsion, mainly because of preserved or increased apical rotation. Possible mechanisms of torsion in single right ventricles include myofiber remodeling and altered ventricular‐ventricular interactions. Understanding myocardial deformation in SVs will improve the ability to interpret ventricular function in this precarious population.

Left ventricular remodelling in long-term survivors after the arterial switch operation for transposition of the great arteries

Aims The objective of this study was to quantify imaging markers of myocardial fibrosis and assess myocardial function in long-term transposition of the great arteries survivors after the arterial switch operation (ASO). Methods and results Paediatric ASO patients were prospectively studied by cardiac magnetic resonance imaging, including first-pass myocardial perfusion, late gadolinium enhancement, and T1 relaxometry, as well as echocardiography for left ventricular (LV) systolic and diastolic function including strain analysis, with comparison to healthy controls. Thirty ASO patients (mean age 15.4 ± 2.9 years vs. 14.1 ± 2.6 years in 28 controls, P = 0.04) were included. Patients had normal LV ejection fraction (EF) (57 ± 5% vs. 59 ± 5%, P = 0.07), but end-diastolic and end-systolic volumes were increased (104 ± 20 mL/m2 vs. 89 ± 10 mL/m2, P < 0.01 and 46 ± 13 mL/m2 vs. 36 ± 7 mL/m2, P < 0.01, respectively). Longitudinal strain at two-, three-, and four-chamber levels of the LV were lower in ASO patients (-19.0 ± 2.6% vs. -20.9 ± 2.3%, P = 0.006, -17.7 ± 2.0% vs. -19.1 ± 2.4%, P = 0.02, and -18.9 ± 1.9% vs. -20.1 ± 1.7%, P = 0.01, respectively), while circumferential strain was higher at all short-axis levels (-24.6 ± 2.3% vs. -19.3 ± 1.6%, P < 0.001 at the mid-ventricular level). LV native T1 times were higher in ASO patients (1042 ± 27 ms vs. 1011 ± 27 ms, P < 0.01) and correlated with LV mass/volume ratio (R = 0.60, P < 0.001). Myocardial scarring or myocardial perfusion defects were not observed in our cohort. Conclusion Children and adolescents after ASO have normal LV systolic function, in line with their overall good clinical health. At a myocardial level however, imaging markers of diffuse myocardial fibrosis are elevated, along with an altered LV contraction pattern. Whether these abnormalities will progress into future clinically significant dysfunction and whether they are harbingers of adverse outcomes remains to be studied.