Effect of left atrial compliance on pulmonary artery pressure: a case report

BACKGROUND: Left ventricular diastolic dysfunction, with secondary atrial pressure elevation, is a well-known concept. On the contrary, effect of left atrial compliance on pulmonary pressure is rarely considered. CASE PRESENTATION: We report the echocardiographic case of a 9-year-old child who presented severe rheumatic mitral valve regurgitation with a giant left atrium, in contrast to a normal artery pulmonary pressure, testifying of the high left atrial compliance. CONCLUSION: Left atrial compliance is an important determinant of symptoms and pulmonary artery pressure in mitral valve disease

Paediatric cardiac CT examinations: impact of the iterative reconstruction method ASIR on image quality - preliminary findings

Background: Radiation dose exposure is of particular concern in children due to the possible harmful effects of ionizing radiation. The adaptive statistical iterative reconstruction (ASIR) method is a promising new technique that reduces image noise and produces better overall image quality compared with routine-dose contrast-enhanced methods. Objective: To assess the benefits of ASIR on the diagnostic image quality in paediatric cardiac CT examinations. Materials and methods: Four paediatric radiologists based at two major hospitals evaluated ten low-dose paediatric cardiac examinations (80 kVp, CTDIvol 4.8-7.9mGy, DLP 37.1-178.9mGy·cm). The average age of the cohort studied was 2.6years (range 1day to 7years). Acquisitions were performed on a 64-MDCT scanner. All images were reconstructed at various ASIR percentages (0-100%). For each examination, radiologists scored 19 anatomical structures using the relative visual grading analysis method. To estimate the potential for dose reduction, acquisitions were also performed on a Catphan phantom and a paediatric phantom. Results: The best image quality for all clinical images was obtained with 20% and 40% ASIR (p < 0.001) whereas with ASIR above 50%, image quality significantly decreased (p < 0.001). With 100% ASIR, a strong noise-free appearance of the structures reduced image conspicuity. A potential for dose reduction of about 36% is predicted for a 2- to 3-year-old child when using 40% ASIR rather than the standard filtered back-projection method. Conclusion: Reconstruction including 20% to 40% ASIR slightly improved the conspicuity of various paediatric cardiac structures in newborns and children with respect to conventional reconstruction (filtered back-projection) alon

Aortic arch shape, arterial mechanics and fluid dynamics in the thoracic aorta after surgery of coarctation (methods and applications with using MRI)

La réparation chirurgicale de la coarctation de l aorte donne aujourd hui d excellents résultats. Malgré ces succès, avoir été opéré d une coarctation dans l enfance expose à un risque élevé d être hypertendu à l âge adulte. Cette hypertension artérielle secondaire est responsable d une surmortalité tardive élevée par évènements cardiovasculaires. Le dépistage et la stratification du risque de développer une hypertension artérielle constituent les objectifs majeurs du suivi. Ce travail, basé sur les techniques non-invasives d exploration artérielle modernes, a permis de caractériser un phénotype artériel à risque d hypertension artérielle chez les patients opérés d une coarctation de l aorte. Dans ce contexte, des méthodes originales de traitement des images d IRM ont été développées afin d étudier les propriétés géométriques et élastiques de l aorte. Le traitement des images obtenues avec les séquences de vélocimétrie en IRM a permis de visualiser la circulation du sang dans l aorte thoracique et d en extraire des paramètres hémodynamiques pertinents.Nous avons ainsi identifié des marqueurs anatomiques (anomalies de géométrie de l arche aortique, en particulier l arche de morphologie gothique) et fonctionnels de l aorte (rigidité, dysfonction endothéliale) prédictifs de l hypertension artérielle chez les patients opérés d une coarctation de l aorte. La coexistence chez un même patient d anomalies de la géométrie de l arche aortique et d altérations de la fonction vasculaire confèrent un risque élevé d évènements cardiovasculaires, justifiant une prise en charge médico-chirurgicale active.The results of the surgical repair of aortic coarctation are excellent. Beside these successes, patients who underwent a coarctation repair in infancy remain at high risk for resting hypertension in later life. This hypertension is responsible for an increased mortality mostly related to cardiovascular events. Screening for hypertension and its risk factors is the main objective of the follow-up. The present work, using modern non invasive imaging techniques, allowed characterizing an arterial phenotype associated with a high risk of hypertension in patients who had undergone coarctation surgery. In this setting, a novel method for calculating pulse wave velocity with using MRI was developed and used to evaluate the mechanical and biophysical properties of the aorta. MRI flow mapping was also used to analyze fluids dynamics in the aorta and to extract haemodynamic parameters.Thus, we have identified anatomical and functional markers of the aorta which are independent predictor of hypertension in post-coarctectomy patients. Indeed, in a given patient, the co-existence of both abnormality of the aortic arch shape and impairment of vascular function confers a high risk for hypertension. Our results are of importance in both preventive and curative strategies.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Conséquences du remaniement de la géométrie de l'arche aortique après une chirurgie de coarctation sur le profil tensionnel à l'effort

PARIS-BIUM (751062103) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF