To test the hypothesis that a new tissue Doppler (TD) approach using angle-correction and transformation of velocity data to color-coded displacement data may objectively quantify regional left ventricular function, in vitro experiments were first performed with an oscillating echo target precisely controlled by a microstepping motor. Displacement varied from 1 to 15 mm (60 to 130 cycles/min) at angles of 0° and 45° to the echo transducer. Custom software transformed TD data to displacement data. Sixty-five subjects were then studied: 35 with wall motion abnormalities and 30 normal controls. Results were compared with independent visual assessment and caliper measurements of endocardial excursion from gray-scale images. In vitro displacement imaging strongly correlated with true displacement (r = 0.99, p <0.0001). In humans, peak transmural displacement discriminated normal results (6.3 ± 3.2 mm) from hypokinesia (2.7 ± 1.8 mm, p <0.05), akinesia (0.4 ± 1.2 mm, p <0.05) from hypokinesia, and dyskinesia (-1.9 ± 1.2 mm, p <0.05) from akinesia. Normal subendocardial displacement was 5.9 ± 2.9 versus 4.0 ± 3.9 mm in the epicardial layer (p <0.01). This displacement gradient was absent in abnormal segments. Displacement data correlated with endocardial excursion by calipers (parasternal views: r = 0.86, all views: r = 0.79, both p <0.0001). Overall accuracy of displacement imaging was 82% (κ = 0.71) versus 66% (κ = 0.43) for visual assessment with caliper data as the standard of reference. Angle-corrected displacement imaging was superior to routine visual assessment and is a promising new method to quantify regional left ventricular function.
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine