Post-operative cardiac lesions after cardiac surgery in childhood

Ex vivo cardiovascular magnetic resonance diffusion weighted imaging in congenital heart disease, an insight into the microstructures of tetralogy of Fallot, biventricular and univentricular systemic right ventricle

PURPOSE

Common types of congenital heart disease exhibit a variety of structural and functional variations which may be accompanied by changes in the myocardial microstructure. We aimed to compare myocardial architecture from magnetic resonance diffusion tensor imaging (DTI) in preserved pathology specimens.

MATERIALS AND METHODS

Pathology specimens (n = 24) formalin-fixed for 40.8 ± 7.9 years comprised tetralogy of Fallot (TOF, n = 10), dextro-transposition of great arteries (D-TGA, n = 8) five with ventricular septal defect (VSD), systemic right ventricle (n = 4), situs inversus totalis (SIT, n = 1) and levo-TGA (L-TGA, n = 1). Specimens were imaged using a custom spin-echo sequence and segmented automatically according to tissue volume fraction. In each specimen T1, T2, fractional anisotropy, mean diffusivity, helix angle (HA) and sheet angle (E2A) were quantified. Pathologies were compared according to their HA gradient, HA asymmetry and E2A mean value in each myocardial segment (anterior, posterior, septal and lateral walls).

RESULTS

TOF and D-TGA with VSD had decreased helix angle gradient by - 0.34°/% and remained symmetric in the septum in comparison to D-TGA without VSD. Helix angle range was decreased by 45°. It was associated with a decreased HA gradient in the right ventricular (RV) wall, i.e. predominant circumferential myocytes. The sheet angle in the septum of TOF was opposing those of the left ventricular (LV) free wall. Univentricular systemic RV had the lowest HA gradient (- 0.43°/%) and the highest HA asymmetry (75%). HA in SIT was linear, asymmetric, and reversed with a sign change at about 70% of the depth at mid-ventricle. In L-TGA with VSD, HA was asymmetric (90%) and its gradients were decreased in the septum, anterior and lateral wall.

CONCLUSION

The organization of the myocytes as determined by DTI differs between TOF, D-TGA, L-TGA, systemic RV and SIT specimens. These differences in cardiac structure may further enlighten our understanding of cardiac function in these diverse congenital heart diseases.

[Specific characteristics of chest X‑ray in childhood : Basics for radiologists]

The radiographic technique of pediatric chest X‑rays is substantially different from that in adults. In nearly all cases ap/pa X‑rays are sufficient and lateral radiographs are rarely needed. In the first years of life the thymus may overshadow the heart, the great vessels and the lung hila. The most important anatomical structures essential for diagnosing pathological findings of the lungs and mediastinum are the trachea with the bifurcation and the main bronchi with the adjacent great vessels. For the assessment of distended lungs and intrathoracic consolidations, fundamental knowledge of the anatomy in childhood and malformations which can involve the airways, the lungs, the heart, as well as systemic and pulmonary vessels are indispensable. Diseases of the pleura and the chest wall should always be investigated by ultrasound. Malignant disorders are rare in children, except for lymphomas. Optimized computed tomography (CT) and/or magnetic resonance imaging (MRI) are crucial in the diagnostic workflow of complex congenital heart diseases, complex lung and airway malformations, pulmonary complications in cystic fibrosis and the diagnostics of all tumors in order to make the right treatment decisions.

Imaging of postoperative tetralogy of Fallot repair

Over the last years, the surgical techniques used to repair Tetralogy of Fallot as well as the cross-sectional cardiac imaging techniques have substantially improved. Now, the survival rate after surgical repair is more than 90% at 40 years old. A follow-up is needed and the imaging evaluation should be guided by the surgical techniques used. This article reviews the most common surgical procedures for a complete repair, the associated anatomic and hemodynamic complications and the role of cardiac imaging, mainly magnetic resonance imaging.

Cardiac CT angiography in children with congenital heart disease

Cardiac imaging plays an important role in both congenital and acquired heart diseases. Cardiac computed tomography (angiography) cCT(A) is a non-invasive, increasingly popular, complementary modality to echocardiography in evaluation of congenital heart diseases (CHD) in children. Despite radiation exposure, cCT(A) is now commonly used for evaluation of the complex CHD, giving information of both intra-cardiac and extra-cardiac anatomy, coronary arteries, and vascular structures. This review article will focus on the fundamentals and essentials for performing cCT(A) in children, including radiation dose awareness, basic techniques, and strengths and weaknesses of cCT(A) compared with cardiac magnetic resonance imaging (cMRI), and applications. The limitations of this modality will also be discussed, including the CHD for which cMRI may be substituted.