Abstract 18663: Reference Values for Left Ventricular Strain by Velocity Vector Imaging in Normal Individuals: Impact of Technical and Clinical Confounders.
Background: Velocity Vector Strain Imaging (VVI-ε) is an off-line ultrasound technique which measures ε at both the endocardial and epicardial level; importantly, it permits ε analysis of DICOM images from machines from different vendors. The aim of this study was to establish reference values for endocardial ε and to investigate clinical and technical factors which might impact its measurement.
Methods: 124 normal individuals (66% women, 39±13 years, age range 18–77) had echocardiography using commercially available machines. VVI-ε was obtained in all three planes (circumferential, radial and longitudinal--C,R,L) by VVI (Tomtec). Technical confounders were considered: image quality, frame rate and machine vendor. We also evaluated effects of: age, gender, heart rate and LV geometry (relative wall thickness-RWT).
Results: Technical factors minimally influenced ε: frame rate (mean value 60fps, range 26–120fps) did not affect εC, ε R, ε L(all p=NS); we saw no difference when comparing pts with excellent/good vs sufficient/fair image quality (p=NS). Furthermore differences in echo machine vendors did not affect mean ε L(19.9±3.6 vs 20.5±3.5%), εR (34.3±9.3 vs 34.3±9.8%), or εC(32.4±6.1 vs 31.5±7.3%; all p=NS). Finally there was no significant gender, age, heart rate, nor LV geometry (relative wall thickness--RWT) (Figure). Mean values [5th and 95th percentiles] for endocardial ε were :32.0% [30.7–33.3%] for εC, 34.1%[32.2–36.0%] for αR, and 20.1% [19.4–20.9%] for εL.
Conclusions: We provide normal reference values for LV endocardial strain in all 3 planes using VVI. VVI- ε gives results which are minimally influenced by age, gender, heart rate and LV geometry. Our findings also show that VVI- ε can used despite less-than-excellent image quality and low frame rate. Finally, ε values obtained by VVI do not appear to differ based on the echo machine used to acquire the images. These findings suggest that VVI is a robust tool for measuring ε in multicenter echo studies.
- © 2010 by American Heart Association, Inc.