An evaluation of the diagnostic efficacy of phase analysis of data from radionuclide ventriculograms in patients with Wolff-Parkinson-White syndrome.

It has been suggested that phase analysis of radionuclide ventriculograms may be of value for detecting and localising the abnormal sequence of ventricular contraction secondary to Wolff-Parkinson-White (WPW) syndrome. The present study was undertaken to test this hypothesis. The space--time sequences of right- and left-ventricular action obtained from radionuclide ventriculograms obtained during rest studies were evaluated in 8 patients with WPW syndrome (confirmed by 12-lead surface electrocardiography) and compared to those of 14 normal subjects. All of the latter showed a consistent ventricular activation pattern, i.e. the first site of ventricular activity in the upper septal region followed by a second site either at the base of the left ventricle or located apically. It was possible to diagnose 11 of the 14 normal subjects (specificity, 79%) and 7 of the 8 patients (sensitivity, 88%). The 4 patients who had been classified as having a left-sided accessory bundle by surface electrocardiography were likewise diagnosed by phase analysis, as were the 2 patients with a confirmed right-sided bypass tract. Two patients with septal posterior accessory pathways could not be identified by phase analysis. Furthermore, cases with an activation pattern which closely resembled that of the 2 patients with right-sided accessory bundles were found to be normal from their ECGs. It is now necessary to evaluate phase analysis against invasive electrophysiological methods in such patients.