Abstract
BackgroundAortic shape has been proposed as an important determinant of adverse haemodynamics following coarctation repair. However, previous studies have not demonstrated a consistent relationship between shape and vascular load. In this study, 3D aortic shape was evaluated using principal component analysis (PCA), allowing investigation of the relationship between 3D shape and haemodynamics.MethodsSixty subjects (38 male, 25.0 ± 7.8 years) with repaired coarctation were recruited. Central aortic haemodynamics including wave intensity analysis were measured noninvasively using a combination of blood pressure and phase contrast cardiovascular magnetic resonance (CMR). 3D curvature and radius data were derived from CMR angiograms. PCA was separately performed on 3D radius and curvature data to assess the role of arch geometry on haemodynamics. Clinical findings were corroborated using 1D vascular models.ResultsThere were no independent associations between 3D curvature and any hemodynamic parameters. However, the magnitude of the backwards compression wave was related to the 1st (r = − 0.36, p = 0.005), 3rd (r = 0.27, p = 0.036) and 4th (r = − 0.31, p = 0.017) principle components of radius. The 4th principle componentof radius also correlated with central aortic systolic pressure. These aortas had larger aortic roots, more transverse arch hypoplasia and narrower aortic isthmuses.ConclusionsThere are major modes of variation in 3D aortic shape after coarctation repair witha modest association between variation in aortic radius and pathological wave reflections, but not with 3D curvature. Taken together, these data suggest that shape is not the major determinant of vascular load following coarctation repair, and calibre is more important than curvature.
Highlights
Operative repair of aortic coarctation in childhood is highly successful and associated with low mortality
The gothic arch has been associated with exercise hypertension and abnormal flow profiles that are suggestive of increased wave reflections [4, 5]
Our main findings include i) It is possible to use principal component analysis (PCA) to characterize the major modes of anatomical variation in arch anatomy, ii) There were no associations between curvature and either aortic hemodynamics or left ventricular (LV) mass or function, iii) changes in radius along the aortic length had a modest association with the magnitude of the Backwards (reflected) Compression Waves (BCW), and iv) 1D haemodynamic models of aortic shapes produced patterns of wave reflection consistent with clinical findings
Summary
Operative repair of aortic coarctation in childhood is highly successful and associated with low mortality. Blood pressure remains elevated, even in patients with no recoarctation [1, 2] This suggests that post repair, patients have an abnormal vascular phenotype. Increased backwards wave reflections have been identified as a cause of increased load and higher left ventricular (LV) mass [1]. Another aspect of vascular phenotype that is often implicated in determining abnormal load in these patients is aortic shape. Aortic shape has been proposed as an important determinant of adverse haemodynamics following coarctation repair. Previous studies have not demonstrated a consistent relationship between shape and vascular load. 3D aortic shape was evaluated using principal component analysis (PCA), allowing investigation of the relationship between 3D shape and haemodynamics
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