Body Surface Electrical Activation Delay Computation From High-Frequency ECGs

The ventricular electrical activation delay is a valuable piece of information in cardiac resynchronization therapy and arrhythmias. The purpose of this study is to introduce electrical activation delay obtained from high-frequency body surface maps (HFBSM). We studied seven patients - three normal (N), three left bundle branch block (LBBB) and one right bundle branch block (RBBB). The amplitude envelopes of the QRS complex in each lead were computed in a frequency band of 100-400 Hz and were averaged (HFQRS). Activation times were defined as the delay from the beginning of the QRS complex to the center of mass of HFQRS, and activation (isochrone) maps were produced. Three different methods of electrical dyssynchrony computation were chosen: maximal activation time difference from the whole surface (HFTAT), delay between lead V1 and V6 (VED) on the 12-lead ECG, and standard deviation of activation times from all electrodes (SDAT). For N/LBBB/RBBB patients, the mean values were: SDAT 3.2/18.3/20.6 ms, VED 3/54/-65 ms, HFTAT 18/71/-83 ms and QRSd 83/141/160 ms. An HFBSM allows easy calculation of HFTAT and SDAT directly from the torso surface. VED provides directional distinction between LBBB and RBBB.