Echocardiographic Fourier phase and amplitude imaging for quantification of ischemic regional wall asynergy: An experimental study using coronary microembolization in dogs

Abstract

This study investigated whether echocardiographic Fourier phase and amplitude imaging can be used to evaluate ischemia-related regional wall asynergy. Because myocardial ischemia delays the onset and peak of endocardial inward motion and reduces its magnitude, Fourier phase and amplitude analysis of two-dimensional echocardiograms may be used to evaluate regional wall motion abnormalities objectively by analyzing temporal sequence and magnitude of endocardial motion. Digital cine loops of left ventricular long- and short-axis views were obtained in six anesthetized dogs at baseline and 1 to 30 min after coronary microembolization and were mathematically transformed using a first-harmonic Fourier algorithm to obtain phase angles and amplitudes of endocardial segments. Mean phase angles and amplitudes were compared with visual wall motion analysis based on a scoring system and quantitative analysis based on segmental fractional area shortening derived from planimetry. Microembolization delayed segmental phase angles by 47 +/- 44 degrees in mild to moderate hypokinesia (fractional shortening [mean +/- SD] 41 +/- 13%) and by 77 +/- 63 degrees in severe hypokinesia (fractional shortening 13 +/- 5%) and reduced segmental amplitudes from 80 +/- 36 gray level intensity at baseline to 53 +/- 34 in segments developing mild to moderate hypokinesia, and from 93 +/- 36 to 35 +/- 28 gray level intensity in segments developing severe hypokinesia. Shifts in segmental phase angles correlated better with dynamic shifts in segmental fractional area shortening than did changes in wall motion score (r = -0.65 vs. r = 0.52, p < 0.001). Echocardiographic Fourier phase imaging can be used to evaluate ischemia-related regional wall asynergy, displaying contraction sequence and magnitude in a simple, objective format.