Session P76.3

Synthesizing Surface ECGs from Intracardiac Electrograms Using an Adaptive Filter Method

J Lian*, H Kraetschmer, D Müssig

Micro Systems Engineering Inc.
Lake Oswego, OR, USA

The recording of surface ECG (SECG) during pacemaker follow-up is time consuming, and is susceptible to motion artifacts and noise interference. The present study investigates the feasibility of synthesizing SECG from the intracardiac electrogram (IEGM) measured by the implant device.
An adaptive filter algorithm was developed to characterize the optimal filters relating the representative IEGM templates to the desired SECG templates. The optimal filters, which vary from sample to sample and are specific to event types (atrial sense, AS; ventricle sense, VS; atrial pace, AP; ventricle pace, VP), were then used to process the IEGM input to generate the pseudo-ECG output. To evaluate the algorithm, a pacemaker was implanted in three anaesthetized pigs. Atrial and ventricular IEGMs with various electrode configurations were respectively recorded by a lead placed in the right ventricle, and a lead inserted in the right atrium. Mixed rhythms were induced, and the SECG was simultaneously recorded. In addition, selected data from Ann Arbor Electrogram Libraries (AAEL) containing arrhythmic episodes of dual-channel IEGM and SECG were tested.
The pseudo-ECG of swine model was generated for mixed rhythms (AS-VS, AS-VP, AP-VS, AP-VP), with different sensing and pacing configurations. The pseudo-ECG was also generated in selected AAEL records containing atrial/ventricle extrasystole, atrial/ventricular flutter, and atrial/ventricular fibrillation. In all tested cases, the pseudo-ECG morphology closely resembled the measured SECG, and clinically relevant cardiac timing and rhythm information were preserved.
In conclusion, the SECG can be reasonably constructed from the IEGM by applying optimal filters characterized by means of the adaptive filter method. The synthetic SECG may provide useful diagnostic information and facilitate implant device follow-up.

(Abstract Control Number: 112)