Assessment of the site of ventricular activation by Fourier analysis of gated blood-pool studies.

We studied the use of first-harmonic Fourier analysis of gated blood-pool images to assess the site of ventricular activation in a group of 12 patients undergoing electrophysiologic pacing studies. We acquired gated blood-pool studies during pacing at up to four sites at each of two different rates. A total of 50 studies were made. At a pacing rate of 100 beats/min, when the pacing electrode was at the right-ventricular apex, 9/13 times the Fourier activation site agreed; at the right-ventricular outflow tract, 7/8; at the anterolateral left-ventricular wall, 4/4. When the Fourier activation site was at the right-ventricular apex, 9/9 times the pacing electrode was there; at the right-ventricular outflow tract, 7/10; in the left ventricle, 4/4. Fourier analysis of gated blood-pool studies can help identify the site of ventricular activation but is not sufficiently accurate to fully replace endocardial mapping.