Session S21.5

Age-Dependency of Left Ventricular Shape Measured from Real-Time 3D Echocardiographic Images

F Maffessanti*, L Sugeng, M Takeuchi, L Weinert,
V Mor-Avi, RM Lang, EG Caiani

Politecnico di Milano
Milano, Italy

Assessment of left ventricular (LV) shape in addition to function could provide new insights into the process of LV remodelling. Real-time 3D echocardiography (RT3DE) allows rapid semi-automated generation of LV endocardial surfaces, which could provide the basis for 3D shape analysis, free of geometric assumptions. Our aim was to quantify LV 3D shape from RT3DE-derived dynamic endocardial surfaces in a large group of normal subjects over a wide range of ages in order to define normal values and test their age-dependency.
Methods: Transthoracic RT3DE datasets (iE33, Philips) were acquired in 147 normal subjects (age 3-88 yrs). Endocardial LV surfaces were semi-automatically detected (Tomtec) and used to compute: 1) novel 3D shape indexes of sphericity (S) and conicity (C), both global and regional, by helical sampling of the LV surface and comparing the resulting signal with that obtained from a sphere or a cone having the same aspect ratio of the LV; 2) regional mean curvature (K) in each of the 17 LV surface segments, estimated from normal and tangent vectors. End-diastolic (ED) and end-systolic (ES) values were computed for each age decade and compared by ANOVA.
Results: In each age group, C and S values were different between ED and ES. The highest values in S (ED: 0.64±0.05; ES: 0.59±0.05) and the lowest values in C (ED: 0.79±0.3; ES: 0.82±0.03) were found in subjects age<20 yrs, with significant difference from the 40-49 yrs group where the lowest S (ED: 0.61±0.03; ES: 0.55±0.04) and the highest C (ED: 0.81±0.02; ES: 0.84±0.02) were noted. In each age group, in all 17 segments, K was larger at ES than ED. For age<20 yrs, a greater K at LV base and in the inferior segment of mid and apical LV was found at ED, compared to other age groups.
Conclusions: 3D LV shape analysis of RT3DE images may provide useful information on LV morphology and help better understand its relation with LV function. In younger subjects, LV is more spherical and less conical than in older subjects, in particular at mid and apical LV, with larger K in basal segments. These results constitute a reference for future comparisons with serial follow up of patients during LV remodelling.

(Abstract Control Number: 277)