Gated blood pool SPECT and phase analysis to assess simulated Wolff-Parkinson-White syndrome in the baboon.

This study assesses the diagnostic potential of a tomographic technique with phase analysis to detect premature electroventricular contraction patterns simulated by pacing in the baboon. The data of gated SPECT were analysed by backprojection of the Fourier coefficients, followed by angulation and integration to thick slices of the entire ventricular mass yielding separate ventricular contraction patterns in three perpendicular views. Electrodes were implanted in each baboon: at the sinoatrial node; posterior, left ventricular; anterior left ventricular; on the left and the right lateral ventricular walls. The atrium was stimulated throughout at a fixed rate. Subsequent ventricular stimuli followed during the QRS complex, such to invoke the appearance of pre-excitation QRS morphology. The first points of activation (FPA) from this algorithm were correctly detected for the RV, for the anterior and posterior sites, although the latter two manifested first points in the RV. LV pacing manifested also as a FPA in the RV, but was followed by a true subsequent point in the LV.